ATI Physical Therapy (ATIP) 10-K16 Mar 232022 FY Annual reportFinancial data

Company Profile

Cover

Cover - USD ($) $ in Millions	12 Months Ended
Cover - USD ($) $ in Millions	Dec. 31, 2022	Mar. 06, 2023	Jun. 30, 2022
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2022
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-39439
Entity Registrant Name	ATI Physical Therapy, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	85-1408039
Entity Address, Address Line One	790 Remington Boulevard
Entity Address, City or Town	Bolingbrook
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60440
City Area Code	630
Local Phone Number	296-2223
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 147.4
Entity Common Stock, Shares Outstanding		207,384,260
Amendment Flag	false
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Entity Central Index Key	0001815849
Common Class A
Document Information [Line Items]
Title of 12(b) Security	Class A common stock, $0.0001 par value
Trading Symbol	ATIP
Security Exchange Name	NYSE
Redeemable Warrants, each whole warrant exercisable for one share of Class A common stock at an exercise price of $11.50 per share
Document Information [Line Items]
Title of 12(b) Security	Redeemable Warrants, each whole warrant exercisable for one share of Class A common stock at an exercise price of $11.50 per share
Trading Symbol	ATIP WS
Security Exchange Name	NYSE

Audit Information

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2022
Auditor Information [Abstract]
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Chicago, Illinois
Auditor Firm ID	238

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 83,139	$ 48,616
Accounts receivable (net of allowance for doubtful accounts of $47,620 and $53,533 at December 31, 2022 and December 31, 2021, respectively)	80,673	82,455
Prepaid expenses	13,526	9,303
Other current assets	10,040	3,204
Assets held for sale	6,755	0
Total current assets	194,133	143,578
Property and equipment, net	123,690	139,730
Operating lease right-of-use assets	226,092	256,646
Goodwill, net	286,458	608,811
Trade name and other intangible assets, net	246,582	411,696
Other non-current assets	2,030	2,233
Total assets	1,078,985	1,562,694
Current liabilities:
Accounts payable	12,559	15,146
Accrued expenses and other liabilities	53,672	64,584
Current portion of operating lease liabilities	47,676	49,433
Current portion of long-term debt	0	8,167
Liabilities held for sale	2,614	0
Total current liabilities	116,521	137,330
Long-term debt, net	531,600	543,799
Warrant liability	98	4,341
Contingent common shares liability	2,835	45,360
Deferred income tax liabilities	18,886	67,459
Operating lease liabilities	218,424	250,597
Other non-current liabilities	1,834	2,301
Total liabilities	890,198	1,051,187
Commitments and contingencies (Note 18)
Mezzanine equity:
Series A Senior Preferred Stock, $0.0001 par value; 1.0 million shares authorized; $1,108.34 stated value per share and 0.2 million shares issued and outstanding at December 31, 2022; none issued and outstanding at December 31, 2021	140,340	0
Stockholders' equity:
Class A common stock, $0.0001 par value; 470.0 million shares authorized; 207.5 million shares issued, 198.4 million shares outstanding at December 31, 2022; 207.4 million shares issued, 197.4 million shares outstanding at December 31, 2021	20	20
Treasury stock, at cost, 0.08 million shares and 0.03 million shares at December 31, 2022 and December 31, 2021, respectively	(146)	(95)
Additional paid-in capital	1,378,696	1,351,597
Accumulated other comprehensive income	4,899	28
Accumulated deficit	(1,339,511)	(847,132)
Total ATI Physical Therapy, Inc. equity	43,958	504,418
Non-controlling interests	4,489	7,089
Total stockholders' equity	48,447	511,507
Total liabilities, mezzanine equity and stockholders' equity	$ 1,078,985	$ 1,562,694
Preferred stock, stated value (dollars per share)	$ 1,108.34

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 47,620	$ 53,533
Preferred stock, par value (dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	1,000,000	1,000,000
Preferred stock, stated value (dollars per share)	$ 1,108.34
Preferred stock, shares issued (in shares)	200,000	0
Preferred stock, shares outstanding (in shares)	200,000	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	470,000,000	470,000,000
Common stock, shares Issued (in shares)	207,500,000	207,400,000
Common stock, shares outstanding (in shares)	198,400,000	197,400,000
Treasury stock (in shares)	80,000	30,000

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Net revenue	$ 635,671	$ 627,871	$ 592,253
Cost of services:
Salaries and related costs	357,982	336,496	306,471
Rent, clinic supplies, contract labor and other	202,568	180,932	166,144
Provision for doubtful accounts	13,869	16,369	16,231
Total cost of services	574,419	533,797	488,846
Selling, general and administrative expenses	114,724	111,809	104,320
Goodwill, intangible and other asset impairment charges	486,262	962,303	0
Operating loss	(539,734)	(980,038)	(913)
Change in fair value of warrant liability	(4,243)	(22,595)	0
Change in fair value of contingent common shares liability	(42,525)	(175,140)	0
Loss on settlement of redeemable preferred stock	0	14,037	0
Interest expense, net	45,278	46,320	69,291
Interest expense on redeemable preferred stock	0	10,087	19,031
Other expense (income), net	3,333	241	(91,002)
(Loss) income before taxes	(541,577)	(852,988)	1,767
Income tax (benefit) expense	(48,530)	(70,960)	2,065
Net loss	(493,047)	(782,028)	(298)
Net (loss) income attributable to non-controlling interests	(668)	(3,700)	5,073
Net loss attributable to ATI Physical Therapy, Inc.	$ (492,379)	$ (778,328)	$ (5,371)
Loss per share of Class A common stock:
Basic (in dollars per share)	$ (2.51)	$ (4.69)	$ (0.04)
Diluted (in dollars per share)	$ (2.51)	$ (4.69)	$ (0.04)
Weighted average shares outstanding:
Basic (in shares)	203,150,000	165,805,000	128,286,000
Diluted (in shares)	203,150,000	165,805,000	128,286,000
Net patient revenue
Net revenue	$ 575,940	$ 561,080	$ 529,585
Other revenue
Net revenue	$ 59,731	$ 66,791	$ 62,668

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Comprehensive Income [Abstract]
Net loss	$ (493,047)	$ (782,028)	$ (298)
Other comprehensive income (loss):
Unrealized gain (loss) on interest rate cap	4,871	1,935	(582)
Comprehensive loss	(488,176)	(780,093)	(880)
Net (loss) income attributable to non-controlling interests	(668)	(3,700)	5,073
Comprehensive loss attributable to ATI Physical Therapy, Inc.	$ (487,508)	$ (776,393)	$ (5,953)

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Previously Reported	Retrospective application of reverse recapitalization	Common Stock	Common Stock Previously Reported	Common Stock Retrospective application of reverse recapitalization	Treasury Stock	Treasury Stock Previously Reported	Treasury Stock Retrospective application of reverse recapitalization	Additional Paid-In Capital	Additional Paid-In Capital Previously Reported	Additional Paid-In Capital Retrospective application of reverse recapitalization	Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Previously Reported	Accumulated Other Comprehensive Income (Loss) Retrospective application of reverse recapitalization	Accumulated Deficit	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment	Accumulated Deficit Previously Reported	Accumulated Deficit Retrospective application of reverse recapitalization	Non-Controlling Interests	Non-Controlling Interests Previously Reported	Non-Controlling Interests Retrospective application of reverse recapitalization
Beginning balance (in shares) at Dec. 31, 2019					128,285,514	938,557	127,346,957
Beginning balance at Dec. 31, 2019	$ 904,919	$ (405)	$ 904,919	$ 0	$ 13	$ 9	$ 4	$ 0	$ 0	$ 0	$ 952,792	$ 952,796	$ (4)	$ (1,325)	$ (1,325)	$ 0	$ (63,028)	$ (405)	$ (63,028)	$ 0	$ 16,467	$ 16,467	$ 0
Beginning balance (in shares) at Dec. 31, 2019								0	0	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Non-cash share-based compensation	1,936										1,936
Other comprehensive income (loss)	(582)													(582)
Distribution to non-controlling interest holders	(4,453)																				(4,453)
Net (loss) income attributable to non-controlling interests	5,073																				5,073
Net loss attributable to ATI Physical Therapy, Inc.	(5,371)																(5,371)
Ending balance (in shares) at Dec. 31, 2020					128,285,514
Ending balance at Dec. 31, 2020	901,117				$ 13			$ 0			954,728			(1,907)			(68,804)				17,087
Ending balance (in shares) at Dec. 31, 2020								0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible Enumeration]		Accounting Standards Update 2016-02
Net proceeds received from FAII in Business Combination (in shares)					25,512,254
Net proceeds received from FAII in Business Combination	210,105				$ 3						210,102
Shares issued through PIPE investment (in shares)					30,000,000
Shares issued through PIPE investment	300,000				$ 3						299,997
Shares issued to Wilco Holdco Series A Preferred stockholders (in shares)					12,845,282
Shares issued to Wilco Holdco Series A Preferred stockholders	128,453				$ 1						128,452
Warrant liability recognized upon the closing of the Business Combination	(26,936)										(26,936)
Contingent common shares liability recognized upon the closing of the Business Combination	(220,500)										(220,500)
Vesting of restricted shares distributed to holders of ICUs (in shares)					691,232
Issuance of common stock upon vesting of restricted stock units and awards (in shares)					105,473
Tax withholdings related to net share settlement of restricted stock awards (in shares)					(29,791)			29,791
Tax withholdings related to net share settlement of restricted stock units and awards	(95)							$ (95)
Non-cash share-based compensation	5,754										5,754
Other comprehensive income (loss)	1,935													1,935
Distribution to non-controlling interest holders	(6,298)																				(6,298)
Net (loss) income attributable to non-controlling interests	(3,700)																				(3,700)
Net loss attributable to ATI Physical Therapy, Inc.	$ (778,328)																(778,328)
Ending balance (in shares) at Dec. 31, 2021	197,400,000				197,409,964
Ending balance at Dec. 31, 2021	$ 511,507				$ 20			$ (95)			1,351,597			28			(847,132)				7,089
Ending balance (in shares) at Dec. 31, 2021	30,000							29,791
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued through PIPE investment (in shares)	30,000,000
Shares issued to Wilco Holdco Series A Preferred stockholders (in shares)	12,845,000
Ending balance (in shares) at Jun. 16, 2021	196,643,000
Beginning balance (in shares) at Dec. 31, 2021	197,400,000				197,409,964
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted shares distributed to holders of ICUs (in shares)					360,371
Issuance of common stock upon vesting of restricted stock units and awards (in shares)					634,256
Tax withholdings related to net share settlement of restricted stock awards (in shares)	50,000				(47,235)			47,235
Tax withholdings related to net share settlement of restricted stock units and awards	$ (51)							$ (51)
Issuance of 2022 Warrants	19,725										19,725
Non-cash share-based compensation	7,374										7,374
Other comprehensive income (loss)	4,871													4,871
Distribution to non-controlling interest holders	(1,932)																				(1,932)
Net (loss) income attributable to non-controlling interests	(668)																				(668)
Net loss attributable to ATI Physical Therapy, Inc.	$ (492,379)																(492,379)
Ending balance (in shares) at Dec. 31, 2022	198,400,000				198,357,356
Ending balance at Dec. 31, 2022	$ 48,447				$ 20			$ (146)			$ 1,378,696			$ 4,899			$ (1,339,511)				$ 4,489
Ending balance (in shares) at Dec. 31, 2022	80,000							77,026

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating activities:
Net loss	$ (493,047)	$ (782,028)	$ (298)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Goodwill, intangible and other asset impairment charges	486,262	962,303	0
Depreciation and amortization	40,590	37,995	39,700
Provision for doubtful accounts	13,869	16,369	16,231
Deferred income tax provision	(48,573)	(71,088)	1,814
Amortization of right-of-use assets	48,253	45,536	44,526
Non-cash share-based compensation	7,374	5,754	1,936
Amortization of debt issuance costs and original issue discount	2,873	3,252	4,109
Non-cash interest expense	3,481	0	6,335
Non-cash interest expense on redeemable preferred stock	0	10,087	19,031
Loss on extinguishment of debt	2,809	5,534	0
Loss on settlement of redeemable preferred stock	0	14,037	0
Loss (gain) on disposal and impairment of assets	9	(5,189)	469
Loss on lease terminations	0	0	3,863
Change in fair value of warrant liability	(4,243)	(22,595)	0
Change in fair value of contingent common shares liability	(42,525)	(175,140)	0
Changes in:
Accounts receivable, net	(12,573)	(10,201)	(3,307)
Prepaid expenses and other current assets	(5,024)	(6,688)	4,841
Other non-current assets	39	(284)	413
Accounts payable	(48)	1,831	798
Accrued expenses and other liabilities	854	(5,288)	9,174
Operating lease liabilities	(53,628)	(50,942)	(42,819)
Other non-current liabilities	28	861	5,056
Medicare Accelerated and Advance Payment Program Funds	(12,288)	(12,605)	26,732
Transaction-related amount due to former owners	0	(3,611)	0
Net cash (used in) provided by operating activities	(65,508)	(42,100)	138,604
Investing activities:
Purchases of property and equipment	(28,147)	(40,293)	(21,887)
Purchases of intangible assets	0	(1,675)	(250)
Proceeds from sale of property and equipment	157	223	328
Business acquisitions, net of cash acquired	0	(4,523)	0
Payment of holdback liabilities related to acquisitions	(135)	0	0
Net cash used in investing activities	(28,048)	(39,889)	(21,809)
Financing activities:
Proceeds from long-term debt	500,000	0	0
Deferred financing costs	(12,952)	0	(350)
Original issue discount	(10,000)	0	0
Principal payments on long-term debt	(555,048)	(456,202)	(8,167)
Proceeds from issuance of Series A Senior Preferred Stock	144,667	0	0
Proceeds from issuance of 2022 Warrants	20,333	0	0
Proceeds from revolving line of credit	48,200	0	68,750
Payments on revolving line of credit	0	0	(68,750)
Cash inflow from Business Combination	0	229,338	0
Payments to Series A Preferred stockholders	0	(59,000)	0
Proceeds from shares issued through PIPE investment	0	300,000	0
Equity issuance costs and original issue discount	(4,935)	(19,233)	0
Payment of contingent consideration liabilities	(203)	0	0
Taxes paid on behalf of employees for shares withheld	(51)	(128)	0
Distribution to non-controlling interest holders	(1,932)	(6,298)	(4,453)
Net cash provided by (used in) financing activities	128,079	(11,523)	(12,970)
Changes in cash and cash equivalents:
Net increase (decrease) in cash and cash equivalents	34,523	(93,512)	103,825
Cash and cash equivalents at beginning of period	48,616	142,128	38,303
Cash and cash equivalents at end of period	83,139	48,616	142,128
Supplemental noncash disclosures:
Derivative changes in fair value	(4,871)	(1,935)	582
Purchases of property and equipment in accounts payable	1,660	4,177	3,010
Warrant liability recognized upon the closing of the Business Combination	0	(26,936)	0
Contingent common shares liability recognized upon the closing of the Business Combination	0	(220,500)	0
Shares issued to Wilco Holdco Series A Preferred stockholders	0	128,453	0
Other supplemental disclosures:
Cash paid for interest	41,617	41,937	58,421
Cash received from hedging activities	3,497	0	0
Cash paid for (received from) taxes	84	81	(1,098)
Clinics
Investing activities:
Proceeds from sale of clinics and Home Health service line	77	248	0
Home Health service line
Investing activities:
Proceeds from sale of clinics and Home Health service line	$ 0	$ 6,131	$ 0

Overview of the Company

Overview of the Company	12 Months Ended
Overview of the Company	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Overview of the Company	Overview of the Company ATI Physical Therapy, Inc., together with its subsidiaries (herein referred to as “we,” “the Company,” “ATI Physical Therapy” and “ATI”), is a nationally recognized healthcare company, specializing in outpatient rehabilitation and adjacent healthcare services. The Company provides outpatient physical therapy services under the name ATI Physical Therapy and, as of December 31, 2022, had 923 clinics (as well as 20 clinics under management service agreements) located in 25 states. The Company offers a variety of services within its clinics, including physical therapy to treat spine, shoulder, knee and neck injuries or pain; work injury rehabilitation services, including work conditioning and work hardening; hand therapy; and other specialized treatment services. The Company’s direct and indirect wholly-owned subsidiaries include, but are not limited to, Wilco Holdco, Inc., ATI Holdings Acquisition, Inc. and ATI Holdings, LLC. On June 16, 2021 (the “Closing Date”), a Business Combination transaction (the “Business Combination”) was finalized pursuant to the Agreement and Plan of Merger ("Merger Agreement"), dated February 21, 2021 between the operating company, Wilco Holdco, Inc. (“Wilco Holdco”), and Fortress Value Acquisition Corp. II (herein referred to as "FAII" and "FVAC"), a special purpose acquisition company. In connection with the closing of the Business Combination, the Company changed its name from Fortress Value Acquisition Corp. II to ATI Physical Therapy, Inc. The Company’s common stock is listed on the New York Stock Exchange ("NYSE") under the symbol “ATIP.” The Business Combination was accounted for as a reverse recapitalization in accordance with U.S. generally accepted accounting principles ("GAAP"). Under this method of accounting, FAII is treated as the acquired company and Wilco Holdco is treated as the acquirer for financial statement reporting and accounting purposes. As a result, the historical operations of Wilco Holdco are deemed to be those of the Company. Therefore, the financial statements included in this report reflect (i) the historical operating results of Wilco Holdco prior to the Business Combination; (ii) the combined results of FAII and Wilco Holdco following the Business Combination on June 16, 2021; (iii) the assets and liabilities of Wilco Holdco at their historical cost; and (iv) the Company’s equity structure for all periods presented. The recapitalization of the number of shares of common stock attributable to the Business Combination is reflected retroactively to the earliest period presented and will be utilized for calculating earnings per share in all prior periods presented. No step-up basis of intangible assets or goodwill was recorded in the Business Combination consistent with the treatment of the transaction as a reverse recapitalization of Wilco Holdco, Inc. Refer to Note 3 - Business Combinations and Divestitures for additional information. Impact of COVID-19 and CARES Act The coronavirus ("COVID-19") pandemic in the United States resulted in changes to our operating environment. We continue to closely monitor the impact of COVID-19 on all aspects of our business, and our priorities remain protecting the health and safety of employees and patients, maximizing the availability of services to satisfy patient needs and improving the operational and financial stability of our business. While we expect the disruption caused by COVID-19 and resulting impacts to diminish over time, we cannot predict the length of such impacts, and if such impacts continue for an extended period, it could have a continued effect on the Company’s results of operations, financial condition and cash flows, which could be material. On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”) was signed into law providing reimbursement, grants, waivers and other funds to assist health care providers during the COVID-19 pandemic. The Company has realized benefits under the CARES Act including, but not limited to, the following: • In 2020, the Company received approximately $91.5 million of general distribution payments under the Provider Relief Fund. These payments have been recognized in other expense (income), net in the consolidated statements of operations throughout 2020 in a manner commensurate with the reporting and eligibility requirements issued by the U.S. Department of Health & Human Services ("HHS"). Based on the terms and conditions of the program, including reporting guidance issued by HHS in 2021, the Company believes that it has met the applicable terms and conditions. This includes, but is not limited to, the fact that the Company’s COVID-19 related expenses and lost revenues for the year ended December 31, 2020 exceeded the amount of funds received. To the extent that reporting requirements and terms and conditions are subsequently modified, it may affect the Company’s ability to comply and ability to retain the funds. • The Company applied for and obtained approval to receive $26.7 million of Medicare Accelerated and Advance Payment Program ("MAAPP") funds during the quarter ended June 30, 2020. During the years ended December 31, 2022 and 2021, the Company applied $12.3 million and $12.6 million in MAAPP funds against the outstanding liability, respectively. During the year ended December 31, 2021, the Company transferred $1.8 million in MAAPP funds as part of the divestiture of its Home Health Service line. During the quarter ended September 30, 2022, the Company met the required performance obligations and performed the remaining services related to the MAAPP funds. Therefore, the remaining funds were applied and repaid during the quarter ended September 30, 2022. As of December 31, 2022 and December 31, 2021, zero and $12.3 million of the funds are recorded in accrued expenses and other liabilities, respectively. • The Company elected to defer depositing the employer portion of Social Security taxes for payments due from March 27, 2020 through December 31, 2020, interest-free and penalty-free. The Company repaid the remaining deferred payments during the fourth quarter of 2022. Related to these payments, as of December 31, 2022 and December 31, 2021, zero and $5.9 million is included in accrued expenses and other liabilities, respectively.

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	Basis of Presentation and Summary of Significant Accounting Policies The accompanying consolidated financial statements of the Company were prepared in accordance with U.S. GAAP and in accordance with the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”). The Company's indirect wholly-owned subsidiaries include, but are not limited to, ATI Holdings Acquisition, Inc. and ATI Holdings, LLC. Liquidity and going concern In accordance with Accounting Standards Codification ("ASC") Topic 205-40, Going Concern , the Company has evaluated whether there are certain conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within twelve months after the date that these consolidated financial statements are issued. This evaluation includes considerations related to the covenants contained in the Company’s 2022 Credit Agreement as well as the Company’s liquidity position overall. As detailed in Note 8 - Borrowings , the Company’s 2022 Credit Agreement contains customary covenants and restrictions, including financial and non-financial covenants. The financial covenants require the Company to maintain $30.0 million of minimum liquidity, as defined in the agreement, at each test date through the first quarter of 2024. Additionally, beginning in the second quarter of 2024, the Company must maintain a Secured Net Leverage Ratio, as defined in the agreement, not to exceed 7.00:1.00. The net leverage ratio covenant decreases in the third quarter of 2024 to 6.75:1.00 and further decreases in the first quarter of 2025 to 6.25:1.00, which level remains applicable through maturity. The financial covenants are tested as of each fiscal quarter end for the respective periods. Failure to comply with these covenants and restrictions would result in an event of default, subject to customary cure periods. In addition, the 2022 Credit Facility contains customary representations and warranties, events of default, reporting and other affirmative covenants and negative covenants, including requirements related to the delivery of independent audit reports without certain going concern qualifications, limitations on indebtedness, liens, investments, negative pledges, dividends, junior debt payments, fundamental changes and asset sales and affiliate transactions. Failure to comply with the 2022 Credit Facility covenants and restrictions, including the provision related to certain going concern qualifications for any fiscal year, including the year ended December 31, 2022, could result in an event of default under the 2022 Credit Facility, subject to customary cure periods. In such an event, all amounts outstanding under the 2022 Credit Facility, together with any accrued interest, could then be declared immediately due and payable. As of December 31, 2022, the Company had $83.1 million in cash and cash equivalents and no available capacity under its 2022 revolving credit facility. As measured based on the definitions in the Company’s 2022 Credit Agreement, liquidity was $72.9 million as of December 31, 2022. The Company has negative operating cash flows, operating losses and net losses. For the year ended December 31, 2022, the Company had cash flow used in operating activities of $65.5 million, operating loss of $539.7 million and net loss of $493.0 million. In addition, as of December 31, 2022, the Company had an accumulated deficit of $1,339.5 million. These results are, in part, due to trends experienced by the Company including a tight labor market for available physical therapy and other healthcare providers in the workforce, visit volume softness, decreases in rate per visit and increases in interest costs. Based on current liquidity and projected cash use, the Company anticipates violation of its $30.0 million minimum liquidity covenant under its 2022 Credit Agreement within the next twelve months. As a result of the above factors, there is substantial doubt about the Company’s ability to continue as a going concern within twelve months following the issuance date of the consolidated financial statements as of and for the period ended December 31, 2022. Improving operating results and cash flow is dependent upon the Company’s ability to achieve its business plan to increase clinical staffing levels and clinician productivity, control costs and capital expenditures, increase patient visit volumes and referrals and stabilize rate per visit. However, there can be no assurance that it will be successful in any of these respects. If the Company does not complete the Transaction as contemplated by the TSA or otherwise access additional financing, the Company will need to consider other alternatives, including pursuing separate amendments to or waivers of the minimum liquidity covenant, the requirement to deliver audited financial statements without certain going concern qualifications, and other requirements under the 2022 Credit Agreement, as well as raising funds from other sources, obtaining alternate financing, disposal of assets, or pursuing other strategic alternatives to improve its liquidity position and business results. There can be no assurance that the Company will be successful in completing the Transaction or accessing such alternative options or financing when needed. Failure to do so could have a material adverse impact on our business, financial condition, results of operations and cash flows, and may lead to events including bankruptcy, reorganization or insolvency. In addition, the report of the Independent Registered Public Accounting Firm accompanying the consolidated financial statements for the year ended December 31, 2022 contains an explanatory paragraph expressing substantial doubt about our ability to continue as a going concern. Absent an amendment or waiver, the 2022 Credit Agreement provides that the receipt of a report of the Independent Registered Public Accounting Firm containing an explanatory paragraph expressing substantial doubt about our ability to continue as a going concern could be an event of default, subject to certain exceptions. Pursuant to the TSA, the First Lien Lenders have agreed that, prior to the Outside Closing Date, they will forbear in the exercise of any rights, remedies, powers, privileges and defenses under the 2022 Credit Agreement arising on account of a default, alleged default or event of default (if any) resulting from the going concern explanatory paragraph in the report of the Independent Registered Public Accounting Firm accompanying the consolidated financial statements for the year ended December 31, 2022. However, if the transactions contemplated by the TSA are not consummated on its terms or at all, the First Lien Lenders could claim that a default or event of default has occurred under the 2022 Credit Agreement. If such claim is not waived by the First Lien Lenders and the Company is unsuccessful in disputing any such claims (including with respect to the applicability of one of the enumerated exceptions to the 2022 Credit Agreement requirement), the Company could be considered to have an event of default after the expiration of the applicable cure periods. In such event, all amounts outstanding under the 2022 Credit Facility, together with any accrued interest, could then be declared immediately due and payable and could be reclassified to current in the Company's consolidated financial statements for the period. A default on our obligations and an acceleration of our indebtedness by our lenders would have a material adverse impact on our business, financial condition, results of operations and cash flows, and may lead to events including bankruptcy, reorganization or insolvency. On March 15, 2023, the Company entered into a Transaction Support Agreement (the “TSA”) with certain of its first lien lenders under the 2022 Credit Agreement (the "First Lien Lenders"), the administrative agent under the 2022 Credit Agreement, holders of its Series A Senior Preferred Stock (the "Preferred Equityholders") and holders of the majority of its common stock (together with the First Lien Lenders and the Preferred Equityholders, the “Parties”), setting forth the principal terms of a comprehensive transaction to enhance the Company's liquidity (the "Transaction"). Pursuant to the TSA, and subject to the terms and conditions thereof, the Parties have agreed to support, act in good faith and take all steps reasonably necessary and desirable to consummate the transactions referenced therein by June 15, 2023 (the “Outside Closing Date”). The TSA contemplates, among other things, (i) a delayed draw new money financing, available under certain circumstances until the 18 month anniversary of the closing date of the transactions, in an aggregate principal amount equal to $25.0 million in the form of new second lien PIK exchangeable notes (“Second Lien PIK Exchangeable Notes”), (ii) exchange of $100.0 million of the aggregate principal amount of the term loans under the 2022 Credit Facility held by certain of the Preferred Equityholders for Second Lien PIK Exchangeable Notes, (iii) a reduction of the thresholds applicable to the minimum liquidity financial covenant under the 2022 Credit Agreement for certain periods, (iv) a waiver of the requirement to comply with the Secured Net Leverage Ratio financial covenant under the 2022 Credit Agreement for the fiscal quarters ending June 30, 2024, September 30, 2024 and December 31, 2024 and a modification of the levels and certain component definitions applicable thereto in the fiscal quarters ending after December 31, 2024, (v) waiver of the requirement for the Company to deliver audited financial statements without certain going concern qualifications for the years ended December 31, 2022, December 31, 2023, and December 31, 2024, (vi) an increase in the interest rate payable on the existing term loans and revolving loans until the achievement of a specified financial metric and (vii) board representation and observer rights, and other changes to the governance of the Company. The Second Lien PIK Exchangeable Notes would be exchangeable for shares of Class A common stock of the Company at a fixed price of $0.25, and the holders thereof would have the right to vote on corporate matters on an as-exchanged basis. The TSA contains certain representations, warranties and other agreements by the Company and Parties. In accordance with the TSA, the First Lien Lenders agreed that, prior to the Outside Closing Date, they will forbear in the exercise of any rights, remedies, powers, privileges and defenses under the 2022 Credit Agreement arising on account of an alleged default or event of default (if any) resulting from the going concern explanatory paragraph in the independent auditors' report accompanying the consolidated financial statements for the year ended December 31, 2022 (the "Credit Agreement Forbearance"). The Parties' obligations under the TSA are, and the closing of the Transaction is, subject to various customary terms and conditions set forth therein, including the execution and delivery of definitive documentation and approval by the Company's stockholders. There is no assurance that the transactions contemplated by the TSA will be consummated on the terms as described above, on a timely basis or at all. The accompanying consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business within twelve months after the date that these consolidated financial statements are issued. Principles of consolidation The consolidated financial statements include the financial statements of the Company, its subsidiaries, entities for which the Company has a controlling financial interest, and variable interest entities ("VIEs") for which the Company is the primary beneficiary. All intercompany balances and transactions have been eliminated in consolidation, and net earnings are reduced by the portion of net earnings attributable to non-controlling interests. Variable interest entities The Company consolidates all variable interest entities where the Company is the primary beneficiary. The Company identifies the primary beneficiary of a VIE as the enterprise that has both: (i) the power to direct the activities of the VIE that most significantly impact the entity's economic performance; and (ii) the obligation to absorb losses or the right to receive benefits of the VIE that could be significant to the entity. The Company may change the original assessment of a VIE upon subsequent events such as the modification of contractual agreements. The Company has an investment in RSFH-ATI Physical Therapy, LLC ("RSFH") that qualifies as a VIE. Based on the provisions of the RSFH agreement, the Company manages the entity and handles all day-to-day operating decisions in exchange for management fees and may receive distributions proportionate with its level of ownership. Accordingly, the Company has the decision-making power over the activities that most significantly impact the entity's economic performance and the obligation to absorb losses or the right to receive benefits that could be significant to the entity. As of December 31, 2022 and 2021, total assets of RSFH were $10.1 million and $13.3 million, respectively, and total liabilities were $5.0 million and $6.5 million, respectively. In general, the assets are available primarily for the settlement of obligations of RSFH. Use of estimates The preparation of the consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates. The effect of any change in estimates will be recognized in the current period of the change. Segment reporting The Company reports segment information based on the management approach. The management approach designates the internal reporting used by management for making decisions and assessing performance as the source of the Company’s reportable segments. All of the Company’s operations are conducted within the United States. Our chief operating decision maker (“CODM”) is our Chief Executive Officer, who reviews financial information presented on a consolidated basis for purposes of making decisions, assessing financial performance and allocating resources. We operate our business as one operating segment and therefore we have one reportable segment. Cash, cash equivalents and restricted cash Cash and cash equivalents include all cash balances and highly liquid investments with original maturities of three months or less when issued. Restricted cash that was included within cash and cash equivalents as presented within our consolidated balance sheets as of December 31, 2022 and our consolidated statements of cash flows for the year ended December 31, 2022 was $0.8 million. Accounts receivable The Company's accounts receivable are reported net of contractual adjustments and allowances for doubtful accounts. The majority of accounts receivable are due from commercial insurance companies, workers' compensation plans, auto personal injury claims and government health programs, such as Medicare or Medicaid. The Company reports accounts receivable at an amount equal to the consideration the Company expects to receive in exchange for providing healthcare services to its patients. Allowance for doubtful accounts The allowance for doubtful accounts is based on estimates of losses related to receivable balances. The risk of collection varies based upon the service, the payor class and the patient’s ability to pay the amounts not reimbursed by the payor. The Company estimates the allowance for doubtful accounts based upon several factors, including the age of the outstanding receivables, the historical experience of collections, the impact of economic conditions and, in some cases, evaluating specific customer accounts for the ability to pay. Management judgment is used to assess the collectability of accounts and the ability of the Company’s customers to pay. The provision for doubtful accounts is included in cost of services in the consolidated statements of operations. When it is determined that a customer account is uncollectible, that balance is written off against the existing allowance. Concentrations of business risk The Company provides physical therapy services to a large number of patients who participate in government healthcare programs, resulting in a customer concentration relating to Medicare and Medicaid’s service reimbursement programs. The Company believes that the concentration of credit risk with respect to other patient accounts receivable is limited due to the large number of patients that make up the Company’s patient base and the dispersion across many different insurance companies, preferred provider organizations and individuals. Net patient revenue Net patient revenue consists of revenue for physical therapy services. Net patient revenue is recognized at an amount equal to the consideration the Company expects to receive from third-party payors, patients and others for services rendered when the performance obligations under the terms of the contract are satisfied. There is an implied contract between the Company and the patient upon each patient visit resulting in the Company’s patient service performance obligation. Generally, the performance obligation is satisfied at a point in time, as each service provided is distinct and future services rendered are not dependent on previously rendered services. The Company has separate contractual agreements with third-party payors (e.g., insurers, managed care programs, government programs, workers' compensation) that provide for payments to the Company at amounts different from its established rates. While these agreements are not considered contracts with the customer, they are used for determining the transaction price for services provided to the patients covered by the third-party payors. The payor contracts do not indicate performance obligations of the Company but indicate reimbursement rates for patients who are covered by those payors when the services are provided. To determine the transaction price associated with the implied contract, the Company includes the estimated effects of any variable consideration, such as contractual allowances and implicit price concessions. When the Company has contracts with negotiated prices for services provided (contracted payors), the Company considers the contractual rates when recording revenue and adjusts for any variable consideration to the transaction price to arrive at revenue. Variable consideration is estimated using a portfolio approach that incorporates whether or not the Company has historical differences from negotiated rates due to non-compliance with contract provisions. Historical results indicate that it is probable that negotiated prices less variable consideration will be realized; therefore, this amount is deemed the transaction price and recorded as revenue. The Company records an estimated provision for doubtful accounts based on historical collections for claims with similar characteristics, such as location of service and type of third-party payor, at the time of recognition. Any subsequent impairment of the related receivable is recorded as provision for doubtful accounts. For non-contracted payors, the Company determines the transaction price by applying established rates to the services provided and adjusting for contractual allowances provided to third-party payors and implicit price concessions. The Company estimates the contractual allowances and implicit price concessions using a portfolio approach based on historical collections for claims with similar characteristics, such as location of service and type of third-party payor, in relation to established rates, because the Company does not have a contract with the underlying payor. Any subsequent changes in estimate on the realization of the receivable is recorded as a revenue adjustment. Management believes that calculating at the portfolio level would not differ materially from considering each patient account separately. The Company continually reviews the revenue transaction price estimation process to consider updates to laws and regulations and changes in third-party payor contractual terms that result from contract renegotiations and renewals. Due to complexities involved in determining amounts ultimately due under reimbursement arrangements with third-party payors and government entities, which are often subject to interpretation, the Company may receive reimbursement for healthcare services that is different from the estimates, and such differences could be material. Other revenue Revenue from the ATI Worksite Solutions business is derived from on-site services provided to clients’ employees including injury prevention, rehabilitation, ergonomic assessments and performance optimization. Revenue is determined based on the number of hours and respective rate for services provided. Revenues from Management Service Agreements (“MSA”) are derived from contractual arrangements whereby the Company manages a non-controlled clinic or clinics for third-party owners. The Company does not have any ownership interest in these clinics. Typically, revenue is determined based on the number of visits conducted at the clinic and recognized when services are performed. Costs, primarily salaries for the Company’s employees, are recorded when incurred. Other revenue includes physical or occupational therapy services and athletic training provided on-site, such as at schools and industrial worksites. Contract terms and rates are agreed to in advance between the Company and the third-parties. Services are typically performed over the contract period, and revenue is recorded in accordance with the contract terms. If the services are paid in advance, revenue is deferred and recognized as the services are performed. Property and equipment Property and equipment acquired is recorded at cost less accumulated depreciation, except during an acquisition of a business, in which case the assets are initially recorded at fair value. Depreciation is calculated using the straight-line method and is provided in amounts sufficient to attribute the cost of depreciable assets to operations over the estimated useful lives. The approximate useful life of each class of property and equipment is as follows: Equipment 3 - 5 years Furniture & fixtures 5 - 7 years Automobiles 3 - 5 years Software 3 - 5 years Buildings 40 years Leasehold improvements Lesser of lease term or estimated useful lives of the assets (generally 5 - 15 years) Major repairs that extend the useful life of an asset are capitalized to the property and equipment account. Routine maintenance and repairs are charged to rent, clinic supplies, contract labor and other expenses and selling, general and administrative expenses. Gains or losses associated with property and equipment retired or sold are included in earnings. Computer software is included in property and equipment and consists of purchased software and internally developed software. The Company capitalizes application-stage development costs for significant internally developed software projects. Once the software is ready for its intended use, these costs are amortized on a straight-line basis over the software’s estimated useful life. Costs recognized in the preliminary project phase and the post-implementation phase, as well as maintenance and training costs, are expensed as incurred. Impairment of long-lived assets The Company reviews the recoverability of long-lived assets whenever events or circumstances occur indicating that the carrying value of the asset may not be recoverable. If the undiscounted cash flows related to the long-lived asset or asset group are not sufficient to recover the remaining carrying value of such asset or asset group, an impairment charge is recognized for the excess carrying amount over the fair value of the asset or asset group. The Company noted triggering events during 2022 which resulted in the recording of impairment losses, which were not material. The Company did not note any triggering events during 2021 or 2020 that resulted in the recording of an impairment loss. Goodwill and intangible assets Goodwill represents the excess of the purchase price over the fair value of assets acquired and liabilities assumed. The Company accounts for goodwill and indefinite-lived intangible assets under Accounting Standards Codification (“ASC”) Topic 350, Intangibles – Goodwill and Other , which requires the Company to test goodwill and other indefinite-lived assets for impairment annually or whenever events or circumstances indicate that impairment may exist. The Company noted triggering events during 2021 and 2022 which resulted in the recording of impairment losses. The Company did not note any triggering events during 2020 that resulted in the recording of an impairment loss. Refer to Note 5 - Goodwill, Trade Name and Other Intangible Assets for further details. Due to the current economic uncertainty resulting from the COVID-19 pandemic, rising interest rates, inflation and other macroeconomic factors, the Company will continue to review the carrying amounts of goodwill and indefinite-lived assets for potential triggering events. The cost of acquired businesses is allocated first to its identifiable assets, both tangible and intangible, based on estimated fair values. Costs allocated to finite-lived identifiable intangible assets are generally amortized on a straight-line basis over the remaining estimated useful lives of the assets. The excess of purchase price over the fair value of identifiable assets acquired, net of liabilities assumed, is recorded as goodwill. The approximate useful life of each class of intangible asset is as follows: ATI Physical Therapy trade name/trademark Indefinite Non-compete agreements 2 - 5 years Other intangible assets 15 years Goodwill and intangible assets with indefinite lives are not amortized but must be reviewed at least annually for impairment. If the impairment test indicates that the carrying value of the reporting unit exceeds its fair value, then a goodwill impairment loss should be recognized in the consolidated statements of operations in an amount equal to the excess carrying value over fair value. If the impairment test indicates that the carrying value of an intangible asset exceeds its fair value, then an impairment loss should be recognized in the consolidated statements of operations in an amount equal to the excess carrying value over fair value. Fair value is determined using valuation techniques based on estimates, judgments and assumptions the Company believes are appropriate in the circumstances. The Company completed the interim and annual impairment analyses of goodwill as of March 31, 2022, June 30, 2022, September 30, 2022, October 1, 2022 and December 31, 2022 by estimating its fair value using an average of a discounted cash flow analysis and comparable public company analysis. The key assumptions associated with determining the estimated fair value include projected revenue growth rates, EBITDA margins, the terminal growth rate, the discount rate and relevant market multiples. The Company completed the interim and annual impairment analyses of the indefinite-lived intangible asset as of March 31, 2022, June 30, 2022, September 30, 2022, October 1, 2022 and December 31, 2022 by estimating its fair value using the relief from royalty method. The key assumptions associated with determining the estimated fair value include projected revenue growth rates, the royalty rate, the discount rate and the terminal growth rate. Deferred financing costs Original debt issuance discounts and costs incurred related to debt financing are recorded as a reduction to debt and amortized ratably over the term of the related debt agreement, using the effective interest method. Deferred financing costs related to revolving credit facilities are recognized as assets and amortized ratably over the term of the related agreement using the effective interest method. Deferred financing costs are amortized to interest expense, net in the Company’s consolidated statements of operations. The Company recognized amortization of deferred debt issuance costs of $1.7 million, $2.3 million and $3.0 million for the years ended December 31, 2022, 2021 and 2020, respectively. The Company recognized amortization of original debt issuance discounts of $1.2 million, $1.0 million and $1.0 million for the years ended December 31, 2022, 2021 and 2020, respectively. Preferred stock Preferred stock is classified as debt, equity or mezzanine equity based on its redemption features. Preferred stock with redemption features outside of the control of the issuer, such as contingent redemption features, is classified as mezzanine equity. Preferred stock with mandatory redemption features is classified as debt. Preferred stock with no redemption features, or redemption features over which the issuer has control, is classified as equity. The Company has preferred stock that is classified as mezzanine equity in the Company's consolidated balance sheets. Refer to Note 11 - Mezzanine and Stockholders' Equity for more information about the Company’s outstanding Series A Senior Preferred Stock. The Company had preferred stock that was classified as debt (redeemable preferred stock) in the Company’s consolidated balance sheets, prior to its redemption as part of the Business Combination. Refer to Note 12 - Wilco Holdco Redeemable Preferred Stock for more information about the Company’s previously outstanding preferred stock. Treasury stock Treasury stock amounts are accounted for under the cost method whereby the entire cost of the acquired stock is recorded as treasury stock. Gains and losses on the subsequent reissuance of shares are credited or charged to paid-in capital in excess of par value using the average-cost method. Warrant liability The Company accounts for its outstanding Public Warrants and Private Placement Warrants in accordance with the guidance contained in ASC 815-40, Derivatives and Hedging - Contracts on an Entity’s Own Equity , and determined that the IPO Warrants do not meet the criteria for equity treatment thereunder. As such, each IPO Warrant must be recorded as a liability and is subject to re-measurement at each balance sheet date. Changes in fair value are recognized in change in fair value of warrant liability in the Company’s consolidated statements of operations. Contingent common shares liability The Company accounts for its potential Earnout Shares and Vesting Shares as a liability in accordance with the guidance in ASC 480, Distinguishing Liabilities from Equity , and ASC 815, Derivatives and Hedging, and is subject to re-measurement at each balance sheet date. Changes in fair value are recognized in the Company’s consolidated statements of operations. Non-controlling interests in consolidated affiliates The consolidated financial statements include all assets, liabilities, revenues and expenses of less-than-100%-owned affiliates where the Company has a controlling financial investment. The Company has separately reflected net (loss) income attributable to the non-controlling interests in net (loss) income in the consolidated statements of operations. Fair value of financial instruments The Company determines fair value measurements used in its consolidated financial statements based upon the exit price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants exclusive of any transaction costs, as determined by either the principal market or the most advantageous market at the measurement date. Inputs used in the valuation techniques to derive fair values are classified based on a three-level hierarchy. The basis for fair value measurements for each level within the hierarchy is described below with Level 1 having the highest priority and Level 3 having the lowest. • Level 1: Observable inputs, which include unadjusted quoted prices in active markets for identical instruments. • Level 2: Observable inputs other than Level 1 inputs, such

Business Combinations and Dives

Business Combinations and Divestitures	12 Months Ended
Business Combinations and Divestitures	Dec. 31, 2022
Business Combination and Asset Acquisition [Abstract]
Business Combinations and Divestitures	Business Combinations and Divestitures The Business Combination As discussed in Note 1 - Overview of the Company , on June 16, 2021 , a business combination between Wilco Holdco and FAII was consummated, which was accounted for as a reverse recapitalization of Wilco Holdco, Inc. At the time of the Business Combination, stockholders of Wilco Holdco, Inc. received 130.3 million shares of the Company’s Class A common stock, par value $0.0001 per share (the “Common Stock”), for the outstanding shares of Wilco Holdco common stock, par value $0.01 per share, that such stockholders owned. Upon distribution of shares of Common Stock to holders of vested and unvested Incentive Common Units (“ICUs”) granted prior to the Business Combination under the Wilco Acquisition, LP 2016 Equity Incentive Plan, 2.0 million of these shares were restricted subject to vesting requirements, resulting in total unrestricted shares of 128.3 million and an exchange ratio of 136.7 unrestricted shares of ATI Physical Therapy, Inc. for every previously outstanding Wilco Holdco share. Immediately following the Business Combination, there were 207.3 million shares issued and 196.6 million outstanding shares of common stock of ATI Physical Therapy, Inc., consisting of the following (in thousands): Class A Common Shares FAII Class A common stock prior to Business Combination 34,500 FAII Class F common stock prior to Business Combination (1) 8,625 Less: FAII Class A common stock redemptions (8,988) FAII common shares (Class A and Class F) 34,137 Add: Shares issued to Wilco Holdco stockholders (2, 3) 130,300 Add: Shares issued through PIPE investment 30,000 Add: Shares issued to Wilco Holdco Series A Preferred stockholders 12,845 Total shares issued as of the Closing Date of the Business Combination (4) 207,282 Less: Vesting Shares (1) (8,625) Less: Restricted shares (3) (2,014) Total shares outstanding as of the Closing Date of the Business Combination (4) 196,643 (1) Per the Merger Agreement, as of the closing of the Business Combination, all Class F shares converted into the equivalent number of Class A common shares and became subject to certain vesting and forfeiture provisions ("Vesting Shares") as detailed in Note 14 - Contingent Common Shares Liability . (2) Includes 1.2 million unrestricted shares upon distribution to holders of vested ICUs under the Wilco Acquisition, LP 2016 Equity Incentive Plan. Refer to Note 10 - Share-Based Compensation for further details. (3) Includes 2.0 million restricted shares upon distribution to holders of unvested ICUs under the Wilco Acquisition, LP 2016 Equity Incentive Plan. Refer to Note 10 - Share-Based Compensation for further details. (4 ) Excludes 15.0 million Earnout Shares, 6.9 million Public Warrants and 3.0 million Private Placement Warrants to purchase Class A common stock. Refer to Note 13 - IPO Warrant Liability and Note 14 - Contingent Common Shares Liability for further details. PIPE investment Concurrently with the closing of the Business Combination, pursuant to Subscription Agreements executed between FAII and certain investors, 30.0 million shares of Class A common stock (the “PIPE” investment) were newly issued in a private placement at a purchase price of $10.00 per share for an aggregate purchase price of $300.0 million. The initial PIPE investment included 7.5 million shares of Class A common stock newly issued to certain investment funds managed by affiliates of Fortress Investment Group LLC (“Fortress”) at a purchase price of $10.00 per share for an aggregate purchase price of $75.0 million. Wilco Holdco Series A Preferred Stock Immediately following the Business Combination, all holders of the previously outstanding shares of Wilco Holdco Series A Preferred Stock received a proportionate share of $59.0 million and 12.8 million shares of ATI Physical Therapy, Inc. Class A common stock based on the terms of the Merger Agreement. Refer to Note 12 - Wilco Holdco Redeemable Preferred Stock for further details. Earnout Shares Subject to the terms and conditions of the Merger Agreement, certain stockholders of Wilco Holdco, Inc. were provided the contingent right to receive, in the aggregate, up to 15.0 million shares of Class A common stock that may be issued pursuant to an earnout arrangement if certain Class A common stock price targets are achieved between the Closing Date and the 10 year anniversary of the Closing Date (“Earnout Shares”). The Earnout Shares are subject to acceleration in the event of a sale or other change in control if the holders of Class A common stock would receive a per share price in excess of the applicable Earnout Shares price target. Refer to Note 14 - Contingent Common Shares Liability and Note 15 - Fair Value Measurements for further details. Vesting Shares Pursuant to the Sponsor Letter Agreement executed in connection with the Merger Agreement, 8.6 million shares of Class F common stock of FAII outstanding immediately prior to the Business Combination converted to potential Class A common shares and became subject to certain vesting and forfeiture provisions (“Vesting Shares”). The Vesting Shares are subject to acceleration in the event of a sale or other change in control if the holders of Class A common stock would receive a per share price in excess of the applicable Vesting Shares price target. Refer to Note 14 - Contingent Common Shares Liability and Note 15 - Fair Value Measurements for further details. IPO Warrants Immediately following the Business Combination, the Company had outstanding Public Warrants to purchase an aggregate of 6.9 million shares of the Company’s Class A common stock ("Public Warrants") and outstanding Private Placement Warrants to purchase an aggregate of 3.0 million shares of the Company's Class A common stock ("Private Placement Warrants") (collectively, the “IPO Warrants”). In conjunction with the B usiness Combination , 3.0 million Private Placement Warrants were transferred and surrendered for no consideration based on terms of the Sponsor Letter Agreement. Refer to Note 13 - IPO Warrant Liability and Note 15 - Fair Value Measurements for further details. The following table reflects the components of cash movement related to the Business Combination, PIPE investment and debt repayments (in thousands): Cash in trust with FAII as of the Closing Date of the Business Combination $ 345,036 Cash used for redemptions of FAII Class A common stock (89,877) FAII transaction costs paid at closing (25,821) Cash inflow from Business Combination 229,338 Wilco Holdco, Inc. transaction costs offset against proceeds (19,233) Net proceeds from FAII in Business Combination 210,105 Cash proceeds from PIPE investment 300,000 Repayment of second lien subordinated loan (231,335) Partial repayment of 2016 first lien term loan (216,700) Cash payment to Wilco Holdco Series A Preferred stockholders (59,000) Wilco Holdco, Inc. transaction costs expensed during 2021 (5,543) Net decrease in cash related to Business Combination, PIPE investment and debt repayments $ (2,473) During 2021, the Company expensed $5.5 million in transaction costs related to the Business Combination, which were classified as selling, general and administrative expenses in the consolidated statements of operations. In addition, $19.2 million of Wilco Holdco, Inc. transaction costs related to the Business Combination were offset against additional paid-in capital in the consolidated statements of changes in stockholders’ equity as these costs were determined to be directly attributable to the recapitalization. Home Health divestiture On October 1, 2021, the Company divested its Home Health service line for a sale price of $7.3 million, and the Company recognized a gain of $5.8 million in other expense (income), net in its consolidated statements of operations. The major classes of assets and liabilities associated with the Home Health service line consisted predominantly of accounts receivable, accrued expenses and other liabilities which were not material. 2021 acquisitions During 2021, the Company completed 3 acquisitions consisting of 7 total clinics. The Company paid approximately $4.5 million in cash and $1.4 million in future payment consideration, subject to certain time or performance conditions set out in the purchase agreements, to complete the acquisitions. The acquisitions qualified for purchase accounting treatment under ASC Topic 805, Business Combinations, whereby the purchase price was allocated to the assets acquired and liabilities assumed based upon their estimated fair values on the respective acquisition dates. Of the total amount of consideration, $5.5 million was allocated to goodwill based on management's valuations, which were preliminary and subject to completion of the Company's valuation analysis through the 12 month measurement period. Management finalized its valuation analysis as of March 31, 2022, and valuation adjustments to the assets acquired and liabilities assumed were not material. Goodwill represents the future economic benefits arising from the other assets acquired that could not be individually identified and separately recognized, such as assembled workforce, synergies, and location. The entire amount of goodwill recorded from these purchases will be deductible for income tax purposes. Acquisition-related costs to complete the transactions, net revenue and net income recognized in 2021 related to the acquisitions were not material, individually and in the aggregate. Unaudited proforma consolidated financial information for the acquisitions have not been included as the results are not material, individually and in the aggregate. 2022 clinics held for sale During the fourth quarter of 2022, the Company classified the assets and liabilities of certain clinics as held for sale as a result of the Company's decision to sell the clinics. The divestiture transactions are anticipated to be completed within twelve months. The clinics did not meet the criteria to be classified as discontinued operations. Major classes of assets and liabilities classified as held for sale as of December 31, 2022 were as follows (in thousands): December 31, 2022 Accounts receivable, net $ 486 Prepaid expenses 23 Property and equipment, net 1,113 Operating lease right-of-use assets 1,929 Goodwill, net 3,192 Other non-current assets 12 Total assets held for sale $ 6,755 Accounts payable $ 22 Accrued expenses and other liabilities 201 Current portion of operating lease liabilities 685 Operating lease liabilities 1,706 Total liabilities held for sale $ 2,614

Revenue from Contracts with Cus

Revenue from Contracts with Customers	12 Months Ended
Revenue from Contracts with Customers	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	Revenue from Contracts with Customers The following table disaggregates net revenue by major service line for the periods indicated below (in thousands): Year Ended December 31, 2022 December 31, 2021 December 31, 2020 Net patient revenue $ 575,940 $ 561,080 $ 529,585 ATI Worksite Solutions (1) 35,515 34,583 30,864 Management Service Agreements (1) 12,857 15,246 15,837 Other revenue (1) 11,359 16,962 15,967 $ 635,671 $ 627,871 $ 592,253 (1) ATI Worksite Solutions, Management Service Agreements and Other revenue are included within other revenue on the face of the consolidated statements of operations. The following table disaggregates net patient revenue for each associated payor class as a percentage of total net patient revenue for the periods indicated below: Year Ended December 31, 2022 December 31, 2021 December 31, 2020 Commercial 57.6 % 56.3 % 53.1 % Government 24.2 % 23.7 % 22.2 % Workers’ compensation 12.4 % 14.3 % 17.6 % Other (1) 5.8 % 5.7 % 7.1 % 100.0 % 100.0 % 100.0 %

Goodwill, Trade Name and Other

Goodwill, Trade Name and Other Intangible Assets	12 Months Ended
Goodwill, Trade Name and Other Intangible Assets	Dec. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, Trade Name and Other Intangible Assets	Goodwill, Trade Name and Other Intangible Assets Our indefinite-lived intangible asset consists of the ATI trade name. We test the indefinite-lived intangible asset for impairment on an annual basis as of October 1. The Company concluded that no indefinite-lived intangible asset impairment existed at the time of annual impairment tests performed for the years ended December 31, 2022, 2021 and 2020. For the annual impairment tests performed in 2022 and 2021, no impairments existed as of October 1 since impairments were recorded on September 30. The Company noted separate interim triggering events during 2022 and 2021 which resulted in the recording of impairment losses. The Company has one reporting unit for purposes of the Company’s goodwill impairment test, which is completed as of October 1. The Company concluded that no goodwill impairment existed at the time of the annual impairment test performed for the years ended December 31, 2022, 2021 and 2020. For the annual impairment tests performed in 2022 and 2021, no impairments existed as of October 1 since impairments were recorded on September 30. The Company noted separate interim triggering events during 2022 and 2021 which resulted in the recording of impairment losses. As the carrying amounts of the Company's goodwill and trade name indefinite-lived intangible asset were impaired during 2022 and 2021, those amounts are more susceptible to an impairment risk if there are unfavorable changes in assumptions and estimates. If the estimated cash flows decrease or market factors change, impairment charges may need to be recorded in the future. Factors that could result in the cash flows being lower than the current estimates include decreased revenue caused by unforeseen changes in the healthcare market or the Company's business, or the inability to achieve the estimated operating margins in the forecasts due to unforeseen factors. Additionally, changes in the broader economic environments could cause changes to the estimated discount rates and comparable company valuation indicators which may impact the estimated fair values. Changes in the carrying amount of goodwill consisted of the following (in thousands): Total Goodwill Goodwill at December 31, 2021 (1) $ 608,811 Impairment charges (318,925) Acquisitions (2) (236) Held for sale reclassifications (3) (3,192) Goodwill at December 31, 2022 $ 286,458 (1) Net of accumulated impairment losses of $726.8 million. (2) Represents final valuation adjustments related to 2021 acquisitions. Refer to Note 3 - Business Combinations and Divestitures for additional information. (3) Goodwill reclassified to assets held for sale is related to clinics held for sale as of December 31, 2022. Refer to Note 3 - Business Combinations and Divestitures for additional information. The table below summarizes the Company’s carrying amount of trade name and other intangible assets at December 31, 2022 and December 31, 2021 (in thousands): December 31, 2022 December 31, 2021 Gross intangible assets: ATI trade name (1) $ 245,000 $ 409,360 Non-compete agreements 2,395 2,405 Other intangible assets 640 640 Accumulated amortization: Accumulated amortization – non-compete agreements (1,126) (425) Accumulated amortization – other intangible assets (327) (284) Total trade name and other intangible assets, net $ 246,582 $ 411,696 (1) Not subject to amortization. The Company recorded $164.4 million of impairment charges related to the trade name indefinite-lived intangible asset during the year ended December 31, 2022. Amortization expense for the years ended December 31, 2022, 2021 and 2020 was immaterial. The Company estimates that amortization expense related to intangible assets is expected to be immaterial over the next five fiscal years and thereafter. Interim impairment testing during 2021 During the quarters ended June 30, 2021 and September 30, 2021, the Company identified interim triggering events. In late July 2021, the Company revised its earnings forecast to reflect (i) the impact of clinician attrition on both volume and operating cost expectations and (ii) payor, state and service mix shift impacts on net patient revenue per visit expectations. These factors accelerated in the second quarter and continued into the third quarter. In October 2021, the Company further revised its forecast to reflect lower than expected patient visit volume. The Company determined that the combination of these factors constituted interim triggering events that required further analysis with respect to potential impairment to goodwill, trade name indefinite-lived intangible and other assets. As it was determined that it was more likely than not that the fair value of our trade name indefinite-lived intangible asset was below its carrying value, the Company performed an interim quantitative impairment test as of the June 30, 2021 and September 30, 2021 balance sheet dates. The Company utilized the relief from royalty method to estimate the fair value of the trade name indefinite-lived intangible asset. The key assumptions associated with determining the estimated fair value include projected revenue growth rates, the royalty rate, the discount rate and the terminal growth rate. As a result of the analyses, during the year ended December 31, 2021, the Company recognized $234.3 million in non-cash interim impairments in the line item goodwill, intangible and other asset impairment charges The Company evaluated its asset groups, including operating lease right-of-use assets that were evaluated based on clinic-level cash flows and clinic-specific market factors, noting no material impairment. As it was determined that it was more likely than not that the fair value of our single reporting unit was below its carrying value, the Company performed an interim quantitative impairment test as of the June 30, 2021 and September 30, 2021 balance sheet dates. In order to determine the fair value of our single reporting unit, the Company utilized an average of a discounted cash flow analysis and comparable public company analysis. The key assumptions associated with determining the estimated fair value include projected revenue growth rates, earnings before interest, taxes, depreciation and amortization ("EBITDA") margins, the terminal growth rate, the discount rate and relevant market multiples. As a result of the analyses, during the year ended December 31, 2021, the Company recognized $726.8 million in non-cash interim impairments in the line item goodwill, intangible and other asset impairment charges in its consolidated statements of operations, which represented the difference between the estimated fair value of the Company’s single reporting unit and its carrying value. Interim impairment testing during 2022 During the quarters ended March 31, 2022, June 30, 2022, September 30, 2022 and December 31, 2022, the Company identified interim triggering events as a result of factors including potential changes in discount rates and decreases in share price. The Company determined that the combination of these factors constituted interim triggering events that required further analysis with respect to potential impairment to goodwill, trade name indefinite-lived intangible and other assets. As it was determined that it was more likely than not that the fair value of our trade name indefinite-lived intangible asset was below its carrying value, the Company performed an interim quantitative impairment test as of the March 31, 2022, June 30, 2022, September 30, 2022 and December 31, 2022 balance sheet dates. The Company utilized the relief from royalty method to estimate the fair value of the trade name indefinite-lived intangible asset. The key assumptions associated with determining the estimated fair value include projected revenue growth rates, the royalty rate, the discount rate and the terminal growth rate. As a result of the analyses, during the year ended December 31, 2022, the Company recognized $164.4 million in non-cash interim impairments in the line item goodwill, intangible and other asset impairment charges in its consolidated statements of operations, which represents the difference between the estimated fair value of the Company’s trade name indefinite-lived intangible asset and its carrying value. The Company evaluated its asset groups, including its operating lease right-of-use assets and leasehold improvement assets that were evaluated based on location-specific cash flows and market factors, noting no material impairment. As it was determined that it was more likely than not that the fair value of our single reporting unit was below its carrying value, the Company performed an interim quantitative impairment test. In order to determine the fair value of our single reporting unit, the Company utilized an average of a discounted cash flow analysis and comparable public company analysis. The key assumptions associated with determining the estimated fair value include projected revenue growth rates, EBITDA margins, the terminal growth rate, the discount rate and relevant market multiples. As a result of the analyses, the Company recognized a $318.9 million non-cash interim impairment in the line item goodwill, intangible and other asset impairment charges in its consolidated statements of operations, which represented the difference between the estimated fair value of the Company’s single reporting unit and its carrying value. The impairment in the fourth quarter included an out of period adjustment to reduce goodwill impairment charges of $8.8 million, of which $1.8 million relates to the year ended December 31, 2021. We evaluated the impact of this error on our previously issued financial statements, assessing both quantitatively and qualitatively, and concluded the error was not material to any of our prior period or the current period financial statements. Fair value determinations require considerable judgment and are sensitive to changes in underlying assumptions, estimates and market factors. Estimating the fair value of the Company’s reporting unit and the indefinite-lived intangible asset requires us to make assumptions and estimates regarding our future plans, as well as industry, economic, and regulatory conditions. These assumptions and estimates include projected revenue growth rates, EBITDA margins, terminal growth rates, discount rates, relevant market multiples, royalty rates and other market factors. If current expectations of future growth rates, margins and cash flows are not met, or if market factors outside of our control change significantly, including discount rates, relevant market multiples, company share price and other market factors, then our reporting unit or the indefinite-lived intangible asset might become impaired in the future, negatively impacting our operating results and financial position. As the carrying amounts of goodwill and the Company’s trade name indefinite-lived intangible asset have been impaired as of December 31, 2022 and written down to fair value, those amounts are more susceptible to an impairment risk if there are unfavorable changes in assumptions and estimates.

Property and Equipment

Property and Equipment	12 Months Ended
Property and Equipment	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment Property and equipment consisted of the following at December 31, 2022 and December 31, 2021 (in thousands): December 31, 2022 December 31, 2021 Equipment $ 38,102 $ 36,278 Furniture and fixtures 17,215 17,141 Leasehold improvements 191,182 183,542 Automobiles 19 19 Computer equipment and software 102,651 95,362 Construction-in-progress 3,727 3,793 352,896 336,135 Accumulated depreciation and amortization (229,206) (196,405) Property and equipment, net (1) $ 123,690 $ 139,730 (1) Excludes $1.1 million reclassified as held for sale as of December 31, 2022. Refer to Note 3 - Business Combinations and Divestitures for additional information. Property and equipment includes internally developed computer software costs in the amount of $64.3 million and $58.7 million as of December 31, 2022 and 2021, respectively. The related amortization expense was $8.2 million, $6.8 million, and $9.8 million for the years ended December 31, 2022, 2021 and 2020, respectively. Depreciation and amortization expense is recorded within rent, clinic supplies, contract labor and other and selling, general and administrative expenses within the consolidated statements of operations, depending on the use of the underlying fixed assets. The depreciation and amortization expense recorded in cost of services relates to revenue-generating assets, which primarily includes clinic leasehold improvements and therapy equipment. The depreciation and amortization expense included in selling, general and administrative expenses is related to infrastructure items, such as corporate leasehold improvements, computer equipment and software. The following table presents the amount of depreciation and amortization expense related to property and equipment recorded in rent, clinic supplies, contract labor and other and selling, general and administrative expenses in the Company’s consolidated statements of operations for the periods indicated below (in thousands): Year Ended December 31, 2022 December 31, 2021 December 31, 2020 Rent, clinic supplies, contract labor and other $ 27,429 $ 26,664 $ 25,409 Selling, general and administrative expenses 12,417 10,873 14,101 Total depreciation expense $ 39,846 $ 37,537 $ 39,510

Accrued Expenses and Other Liab

Accrued Expenses and Other Liabilities	12 Months Ended
Accrued Expenses and Other Liabilities	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued Expenses and Other Liabilities	Accrued Expenses and Other Liabilities Accrued expenses and other liabilities consisted of the following at December 31, 2022 and December 31, 2021 (in thousands): December 31, 2022 December 31, 2021 Salaries and related costs $ 28,949 $ 27,257 Credit balances due to patients and payors 6,117 4,240 Accrued professional fees 5,551 5,998 Accrued contract labor 4,483 2,057 Accrued occupancy costs 2,410 1,895 CARES Act funds (1) — 18,179 Other payables and accrued expenses 6,162 4,958 Total $ 53,672 $ 64,584 (1) Includes current portion of MAAPP funds received and deferred employer Social Security tax payments.

Borrowings

Borrowings	12 Months Ended
Borrowings	Dec. 31, 2022
Debt Disclosure [Abstract]
Borrowings	Borrowings Long-term debt consisted of the following at December 31, 2022 and December 31, 2021 (in thousands): December 31, 2022 December 31, 2021 Senior Secured Term Loan (1, 2) (due February 24, 2028) $ 503,481 $ — Revolving Loans (3) (due February 24, 2027) 48,200 — 2016 first lien term loan (4) — 555,048 Less: unamortized debt issuance costs (11,137) (1,935) Less: unamortized original issue discount (8,944) (1,147) Total debt, net 531,600 551,966 Less: current portion of long-term debt — (8,167) Long-term debt, net $ 531,600 $ 543,799 (1) Interest rate of 12.1% at December 31, 2022, with interest payable in designated installments at a variable interest rate. The effective interest rate for the Senior Secured Term Loan was 13.1% at December 31, 2022. (2) During the third and fourth quarters of 2022, the Company elected to pay a portion of its interest in-kind on its Senior Secured Term Loan by capitalizing and adding such interest to the principal amount of the debt. As of December 31, 2022, the Company recognized paid in-kind interest in the amount of $3.5 million. (3) Interest rate of 8.3% at December 31, 2022, with interest payable in designated installments at a variable interest rate. (4) Loan balance was repaid in its entirety on February 24, 2022. The effective interest rate for the 2016 first lien term loan was 4.9% at December 31, 2021. 2016 first and second lien credit agreements In connection with the Business Combination on June 16, 2021, the Company paid down $216.7 million of its 2016 first lien term loan. The Company recognized $1.7 million in loss on debt extinguishment related to the derecognition of the proportionate amount of remaining unamortized deferred financing costs and unamortized original issue discount associated with the partial debt repayment. In connection with the Business Combination on June 16, 2021, the Company paid $231.3 million to settle its second lien subordinated term loan. The Company recognized $3.8 million in loss on debt extinguishment related to the derecognition of the remaining unamortized deferred financing costs in conjunction with the debt repayment. The total loss on debt extinguishment associated with the partial repayment of the first lien term loan and the settlement of the second lien subordinated term loan was $5.5 million for the year ended December 31, 2021. This amount has been reflected in other expense (income), net in the consolidated statements of operations. On February 24, 2022, the Company paid $555.0 million to settle its existing term loan (the "2016 first lien term loan"). The Company accounted for the transaction as a debt extinguishment and recognized $2.8 million in loss on debt extinguishment related to the derecognition of the remaining unamortized deferred financing costs and unamortized original issue discount in conjunction with the debt repayment. The loss on debt extinguishment associated with the repayment of the 2016 first lien term loan has been reflected in other expense (income), net in the consolidated statements of operations. 2022 Credit Agreement On February 24, 2022 (the "Refinancing Date"), the Company entered into various financing arrangements to refinance its existing long-term debt (the "2022 Debt Refinancing"). As part of the 2022 Debt Refinancing, ATI Holdings Acquisition, Inc. (the "Borrower"), an indirect subsidiary of ATI Physical Therapy, Inc., entered into a credit agreement among the Borrower, Wilco Intermediate Holdings, Inc. ("Holdings"), as loan guarantor, Barclays Bank PLC, as administrative agent and issuing bank, and a syndicate of lenders (the "2022 Credit Agreement"). The 2022 Credit Agreement provides a $550.0 million credit facility (the "2022 Credit Facility") that is comprised of a $500.0 million senior secured term loan (the "Senior Secured Term Loan") which was fully funded at closing and a $50.0 million "super priority" senior secured revolver (the "Revolving Loans") with a $10.0 million letter of credit sublimit. The 2022 Credit Facility refinanced and replaced the Company's prior credit facility for which Barclays Bank PLC served as administrative agent for a syndicate of lenders. In connection with the 2022 Debt Refinancing, the Company also entered into a preferred stock purchase agreement, consisting of senior preferred stock with detachable warrants to purchase common stock for an aggregate stated value of $165.0 million (collectively, the “Preferred Stock Financing”). See Note 11 - Mezzanine and Stockholders' Equity for further information regarding the Preferred Stock Financing. The Company capitalized debt issuance costs totaling $12.5 million related to the 2022 Credit Facility as well as an original issue discount of $10.0 million, which are amortized over the terms of the respective financing arrangements. The Senior Secured Term Loan matures on February 24, 2028 and bears interest, at the Company's election, at a base interest rate of the Alternate Base Rate ("ABR"), as defined in the agreement, plus an applicable credit spread, or the Adjusted Term SOFR Rate, as defined in the agreement, plus an applicable credit spread. The credit spread is determined based on a pricing grid and the Company's Secured Net Leverage Ratio. The Company may elect to pay 2.0% interest in-kind at a 0.5% premium during the first year under the agreement. The Company elected to pay a portion of its interest in-kind during the third and fourth quarters of 2022. As of December 31, 2022, borrowings on the Senior Secured Term Loan bear interest at 1-month SOFR, subject to a 1.0% floor, plus 7.25% plus the 0.5% paid-in-kind interest premium. The Revolving Loans are subject to a maximum borrowing capacity of $50.0 million and mature on February 24, 2027. Borrowings on the Revolving Loans bear interest, at the Company's election, at a base interest rate of the ABR, as defined in the agreement, plus an applicable credit spread, or the Adjusted Term SOFR Rate, as defined in the agreement, plus an applicable credit spread. The credit spread is determined based on a pricing grid and the Company's Secured Net Leverage Ratio. In December 2022, the Company drew $48.2 million in Revolving Loans. As of December 31, 2022, $48.2 million in Revolving Loans were outstanding and bearing interest at 1-month SOFR plus a credit spread of 4.1%. The Company capitalized issuance costs of $0.5 million related to the Revolving Loans. Unamortized issuance costs of $0.2 million related to the revolving loans under the 2016 credit agreement were added to the balance of unamortized issuance costs to be amortized over the term of the Revolving Loans pursuant to debt extinguishment accounting guidance. Commitment fees on the Revolving Loans are payable quarterly at 0.5% per annum on the daily average undrawn portion for the quarter and are expensed as incurred. The balances of unamortized issuance costs related to the Revolving Loans and the revolving loans under the 2016 credit agreement, respectively, were $0.6 million as of December 31, 2022, and $0.3 million as of December 31, 2021. The 2022 Credit Facility is guaranteed by certain of the Company’s subsidiaries and is secured by substantially all of the assets of Holdings, the Borrower and the Borrower’s wholly owned subsidiaries, including a pledge of the stock of the Borrower, in each case, subject to customary exceptions. The 2022 Credit Agreement contains customary covenants and restrictions, including financial and non-financial covenants. The financial covenants require the Company to maintain $30.0 million of minimum liquidity, as defined in the agreement, at each test date through the first quarter of 2024. Additionally, beginning in the second quarter of 2024, the Company must maintain a Secured Net Leverage Ratio, as defined in the agreement, not to exceed 7.00:1.00. The net leverage ratio covenant decreases in the third quarter of 2024 to 6.75:1.00 and further decreases in the first quarter of 2025 to 6.25:1.00, which remains applicable through maturity. The financial covenants are tested as of each fiscal quarter end for the respective periods. As of December 31, 2022, the Company has met its minimum liquidity financial covenant. The 2022 Credit Facility contains customary representations and warranties, events of default, reporting and other affirmative covenants and negative covenants, including requirements related to the delivery of independent audit reports without certain going concern qualifications, limitations on indebtedness, liens, investments, negative pledges, dividends, junior debt payments, fundamental changes and asset sales and affiliate transactions. Failure to comply with the 2022 Credit Facility covenants and restrictions could result in an event of default under the 2022 Credit Facility, subject to customary cure periods. In such an event, all amounts outstanding under the 2022 Credit Facility, together with any accrued interest, could then be declared immediately due and payable. Under the 2022 Credit Facility, the Company may be required to make certain mandatory prepayments upon the occurrence of certain events, including: an event of default, a Prepayment Asset Sale or receipt of Net Insurance Proceeds in excess of $15.0 million, or excess cash flows exceeding certain thresholds. A Prepayment Asset Sale includes dispositions at fair market value, and Net Insurance Proceeds is generally defined as insurance proceeds received on a covered loss or as a result of assets taken under the power of eminent domain, net of costs related to the matter. The Company had letters of credit totaling $1.8 million and $1.2 million under the letter of credit sub-facility on the revolving credit facilities as of December 31, 2022 and December 31, 2021, respectively. The letters of credit auto-renew on an annual basis and are pledged to insurance carriers as collateral. Aggregate maturities of long-term debt at December 31, 2022 are as follows (in thousands): 2023 $ — 2024 — 2025 — 2026 — 2027 48,200 Thereafter 503,481 Total future maturities 551,681 Unamortized original issue discount and debt issuance costs (20,081) Total debt, net $ 531,600

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
Employee Benefit Plans	Dec. 31, 2022
Retirement Benefits [Abstract]
Employee Benefit Plans	Employee Benefit PlansThe Company maintains a defined contribution 401(k) retirement plan for its full-time employees. The plan allows all participants to make elective pretax contributions of up to 100% of their compensation, up to a maximum amount as limited by law. The Company makes matching contributions to the plan on behalf of the employee in the amount of 50% of the first 6% of the contributing participant’s elective deferral contribution. Matching contributions to the plan were $4.9 million, $4.6 million and $4.7 million for the years ended December 31, 2022, 2021 and 2020, respectively. The following table presents the Company’s matching contributions to the plan recorded in cost of services and selling, general and administrative expenses in the consolidated statements of operations for the periods indicated below (in thousands): Year Ended December 31, 2022 December 31, 2021 December 31, 2020 Salaries and related costs $ 4,374 $ 4,102 $ 4,206 Selling, general and administrative expenses 559 532 520 Total $ 4,933 $ 4,634 $ 4,726

Share-Based Compensation

Share-Based Compensation	12 Months Ended
Share-Based Compensation	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
Share-Based Compensation	Share-Based Compensation The Company recognizes compensation expense for all share-based compensation awarded to employees, net of forfeitures, using a fair value-based method. The grant-date fair value of each award is amortized to expense on a straight-line basis over the award’s vesting period. Compensation expense associated with share-based awards is included in salaries and related costs and selling, general and administrative expenses in the accompanying consolidated statements of operations, depending on whether the award recipient is a clinic-level or corporate employee, respectively. Share-based compensation expense is adjusted for forfeitures as incurred. Wilco Acquisition, LP 2016 Equity Incentive Plan Prior to the Business Combination, Wilco Acquisition, LP was the parent company of Wilco Holdco, Inc. and its subsidiaries. In 2016, the Company adopted the Wilco Acquisition, LP 2016 Equity Incentive Plan (the “2016 Plan”) under which, prior to the Business Combination, it granted profit interests of Wilco Acquisition, LP in the form of Incentive Common Units, to members of management, key employees and independent directors of Wilco Acquisition, LP and its subsidiaries. Service-based vesting Prior to the Business Combination, Wilco Acquisition, LP granted Incentive Common Units, subject to service-based vesting, to members of management, key employees and independent directors. Following the closing of the Business Combination, holders of service-based ICUs were entitled to a distribution of a number of Class A common shares of ATI Physical Therapy, Inc. based on the distribution priorities under the Wilco Acquisition, LP limited partnership agreement. The shares related to vested service-based ICUs were distributed as unrestricted Class A common shares of ATI. The shares related to unvested service-based ICUs were distributed as restricted Class A common shares of ATI eligible to vest over the shorter of: (a) the existing vesting schedule applicable to the underlying ICUs, or (b) in installments on each quarterly anniversary of the closing over three years post-closing, subject to the grantee's continued service through each vesting date. Pursuant to the 2016 Plan, total share-based compensation expense related to service-based awards recognized in the years ended December 31, 2022, 2021 and 2020 was $0.8 million, $2.7 million and $1.9 million, respectively. For the year ended December 31, 2022, 0.1 million shares distributed to holders of service-based ICUs vested, and forfeitures related to shares distributed to holders of service-based ICUs were immaterial. There were no service-based awards granted under the 2016 Plan during the year ended December 31, 2022. As of December 31, 2022, the remaining unvested restricted shares distributed to holders of service-based ICUs totaled 0.1 million Class A common shares, with unrecognized compensation expense of $0.6 million to be recognized over a weighted-average period of 1.4 years. Performance-based vesting Prior to the Business Combination, Wilco Acquisition, LP granted Incentive Common Units, subject to performance-based vesting, to members of management, key employees and independent directors. Following the closing of the Business Combination, holders of performance-based ICUs were entitled to a distribution of a number of Class A common shares of ATI Physical Therapy, Inc. based on the distribution priorities under the Wilco Acquisition, LP limited partnership agreement. The shares related to performance-based ICUs were distributed to holders as restricted Class A common shares of ATI eligible to vest in installments on each quarterly anniversary of the closing over the shorter of: (a) the eight-year period from the original grant date of the underlying ICUs, or (b) three years post-closing, subject to the grantee’s continued service through each vesting date. Based on the terms of the performance-based ICUs, the performance-based awards follow the treatment of an initial public offering ("IPO") as a result of the Business Combination and, therefore, converted to service-based vesting requirements. Prior to the Business Combination, no share-based compensation expense was recognized related to the performance-based awards, as a change-in-control or IPO cannot be assessed as probable prior to its occurrence. Following the closing of the Business Combination, the Company began recognizing share-based compensation expense associated with the performance-based awards. Recognition of such expense follows a straight-line expense allocation based on the original grant date and the shorter of (a) the eight-year period from the original grant date of the underlying ICUs, or (b) three years post-closing of the Business Combination. For the years ended December 31, 2022 and 2021, share-based compensation expense related to the performance-based awards was $0.3 million and $2.5 million, respectively. For the year ended December 31, 2022, 0.2 million shares distributed to holders of performance-based ICUs vested, and 0.1 million shares distributed to holders of performance-based ICUs were forfeited. There were no performance-based awards granted under the 2016 Plan during the year ended December 31, 2022. As of December 31, 2022, the remaining unvested restricted shares distributed to holders of performance-based ICUs totaled 0.1 million shares, with unrecognized compensation expense of $0.5 million to be recognized over a weighted-average period of 1.5 years. ATI 2021 Equity Incentive Plan The Company adopted the ATI Physical Therapy 2021 Equity Incentive Plan (the "2021 Plan") under which it may grant equity interests of ATI Physical Therapy, Inc., in the form of stock options, stock appreciation rights, restricted stock awards and restricted stock units, to members of management, key employees and independent directors of the Company and its subsidiaries. The Compensation Committee is authorized to make grants and to make various other decisions under the 2021 Plan. The maximum number of shares reserved for issuance under the 2021 Plan is approximately 21.3 million. As of December 31, 2022, approximately 10.9 million shares were available for future grant. Stock options The Company grants stock options to members of management, key employees and independent directors. Stock options typically vest in equal annual installments over a service period ranging from three Pursuant to the 2021 Plan, total share-based compensation expense related to stock options recognized in the years ended December 31, 2022 and 2021 was approximately $1.3 million and $0.1 million, respectively. No share-based compensation expense was recognized in the year ended December 31, 2020 related to stock options. The following table summarizes the activity of stock options for the year ended December 31, 2022 (aggregate intrinsic value in thousands): Number of Options Weighted-Average Exercise Price Weighted-Average Contractual Term (in years) Aggregate Intrinsic Value Outstanding, January 1, 2022 774,796 $ 3.41 9.9 $ 9 Granted 6,369,881 1.69 N/A N/A Exercised — — N/A — Forfeited/Cancelled (1,831,938) 1.98 N/A N/A Outstanding, December 31, 2022 5,312,739 $ 1.84 9.1 $ — Exercisable, December 31, 2022 202,337 $ 3.40 6.9 $ — Expected to vest, December 31, 2022 5,110,402 $ 1.78 9.2 $ — The fair values of each stock option granted was determined using the Black-Scholes option-pricing model. As the Company does not have sufficient historical share option exercise experience for such "plain-vanilla" awards, the expected option term was determined using the simplified method, which is the average of the option's vesting and contractual term. Volatility is measured using the historical volatility of certain comparable public companies, using daily log-returns of stock prices, as adjusted for the impact of financial leverage. The risk-free interest rate reflects the U.S. Treasury yield curve in effect at the time of the grant. The following table summarizes the weighted-average grant-date fair value and assumptions used to develop the fair value estimates for the options granted in 2022 and 2021. No stock options were granted under the 2021 Plan during the year ended December 31, 2020: 2022 2021 Weighted-average grant-date fair value of options $0.98 $1.69 Risk-free interest rate 1.74% 1.45% Term (years) 6.2 6.0 Volatility 61.19% 51.67% Expected dividend —% —% As of December 31, 2022, the unrecognized compensation expense related to stock options was $4.1 million, to be recognized over a weighted-average period of 2.9 years. Restricted stock units The Company grants restricted stock units (“RSUs”) to members of management, key employees and independent directors. RSUs are time-based vesting awards and are subject to the continued service of the employee or non-employee director over the vesting period. RSUs typically vest in equal annual installments over one Pursuant to the 2021 Plan, total share-based compensation expense related to RSUs recognized in the years ended December 31, 2022 and 2021 was approximately $4.4 million and $0.1 million, respectively. No share-based compensation expense was recognized in the year ended December 31, 2020 related to RSUs. The following table summarizes the activity of unvested RSUs and the respective weighted-average grant date fair value per RSU for the year ended December 31, 2022: 2022 RSUs Weighted-Average Grant Date Fair Value Outstanding and unvested, beginning of year 404,235 $ 3.41 Granted (1) 5,428,281 2.08 Vested (489,461) 3.58 Forfeited (1,143,246) 2.23 Outstanding and unvested, end of year 4,199,809 $ 1.99 (1) The vesting start date for certain RSUs granted in 2022 is the Closing Date During the year ended December 31, 2021, the Company granted approximately 0.4 million RSUs with a weighted-average grant date fair value of $3.41. No RSUs were granted or outstanding for the year ended December 31, 2020. During the year ended December 31, 2022, the fair value of vested RSUs was $1.8 million and no RSUs vested in 2021. As of December 31, 2022, the unrecognized compensation expense related to RSUs was $5.6 million, to be recognized over a weighted-average period of 1.9 years. Restricted stock awards The Company grants restricted stock awards (“RSAs”) to members of management and key employees. RSAs are time-based vesting awards and are subject to the continued service of the employee over the vesting period. RSAs typically vest in equal quarterly installments over a service period of three years from the grant date. The vesting start date for the RSAs granted in 2021 is the Closing Date. The fair value of restricted stock was based on the price of the Company’s common stock on the grant date. Pursuant to the 2021 Plan, total share-based compensation expense related to RSAs recognized in the years ended December 31, 2022 and 2021 was approximately $0.5 million and $0.4 million, respectively. No share-based compensation expense was recognized in the year ended December 31, 2020 related to RSAs. The following table summarizes the activity of unvested RSAs and respective weighted-average grant date fair value per RSA for the year ended December 31, 2022: 2022 RSAs Weighted-Average Grant Date Fair Value Outstanding and unvested, beginning of year 447,731 $ 3.42 Granted — — Vested (144,795) 3.42 Forfeited (128,227) 3.42 Outstanding and unvested, end of year 174,709 $ 3.42 During the year ended December 31, 2021, the Company granted approximately 0.6 million RSAs with a weighted-average grant date fair value of $3.42. No RSAs were granted or outstanding for the year ended December 31, 2020. During the years ended December 31, 2022 and 2021, the fair value of vested RSAs was $0.5 million and $0.4 million, respectively. As of December 31, 2022, the unrecognized compensation expense related to RSAs was $0.6 million, to be recognized over a weighted-average period of 1.5 years.

Mezzanine and Stockholders' Equ

Mezzanine and Stockholders' Equity	12 Months Ended
Mezzanine and Stockholders' Equity	Dec. 31, 2022
Equity [Abstract]
Mezzanine and Stockholders' Equity	Mezzanine and Stockholders' Equity ATI Physical Therapy, Inc. Series A Senior Preferred Stock In connection with the 2022 Debt Refinancing, the Company issued 165,000 shares of non-convertible preferred stock (the "Series A Senior Preferred Stock") plus 5.2 million warrants to purchase shares of the Company's common stock at an exercise price of $3.00 per share (the "Series I Warrants") and warrants to purchase 6.3 million shares of the Company's common stock at an exercise price equal to $0.01 per share (the "Series II Warrants"). The shares of the Series A Senior Preferred Stock have a par value of $0.0001 per share and an initial stated value of $1,000 per share, for an aggregate initial stated value of $165.0 million. The Company is authorized to issue 1.0 million shares of preferred stock per the Certificate of Designation. As of December 31, 2022, there was 0.2 million shares of Series A Senior Preferred Stock issued and outstanding. The gross proceeds received from the issuance of the Series A Senior Preferred Stock and the Series I and Series II Warrants were $165.0 million, which was allocated among the instruments based on the relative fair values of each instrument. Of the gross proceeds, $144.7 million was allocated to the Series A Senior Preferred Stock, $5.1 million to the Series I Warrants and $15.2 million to the Series II Warrants. The resulting discount on the Series A Senior Preferred Stock will be recognized as a deemed dividend when those shares are subsequently remeasured upon becoming redeemable or probable of becoming redeemable. The Company recognized $2.9 million in issuance costs and $1.4 million of original issue discount related to the Series A Senior Preferred Stock. The following table reflects the components of proceeds related to the Series A Senior Preferred Stock (in thousands): Gross proceeds allocated to Series A Senior Preferred Stock $ 144,667 Less: original issue discount (1,447) Less: issuance costs (2,880) Net proceeds received from issuance of Series A Senior Preferred Stock $ 140,340 The Series A Senior Preferred Stock has priority over the Company's Class A common stock and all other junior equity securities of the Company, and is junior to the Company's existing or future indebtedness and other liabilities (including trade payables), with respect to payment of dividends, distribution of assets, and all other liquidation, winding up, dissolution, dividend and redemption rights. The Series A Senior Preferred Stock carries an initial dividend rate of 12.0% per annum (the "Base Dividend Rate"), payable quarterly in arrears. Dividends will be paid in-kind and added to the stated value of the Series A Senior Preferred Stock. The Company may elect to pay dividends on the Series A Senior Preferred Stock in cash beginning on the third anniversary of the Refinancing Date and, with respect to any such dividends paid in cash, the dividend rate then in effect will be decreased by 1.0%. The Base Dividend Rate is subject to certain adjustments, including an increase of 1.0% per annum on the first day following the fifth anniversary of the Refinancing Date and on each one-year anniversary thereafter, and 2.0% per annum upon the occurrence of either an Event of Noncompliance (as defined in the Certificate of Designation) or a failure by the Company to redeem in full all Series A Senior Preferred Stock upon a Mandatory Redemption Event, which includes a change of control, liquidation, bankruptcy or certain restructurings. The paid in-kind dividends related to the Series A Preferred Stock were $17.9 million for the year ended December 31, 2022. As of December 31, 2022, the accumulated paid in-kind dividends related to the Series A Preferred Stock were $17.9 million and the aggregate stated value was $182.9 million. The following table presents the change in the aggregate stated value and stated value per share of the Series A Senior Preferred Stock since the Refinancing Date (in thousands, except per share data): Series A Senior Preferred Stock Aggregate stated value as of February 24, 2022 $ 165,000 Accumulated paid in-kind dividends as of December 31, 2022 17,876 Aggregate stated value as of December 31, 2022 $ 182,876 Preferred shares issued and outstanding as of December 31, 2022 165 Stated value per share as of December 31, 2022 $ 1,108.34 The Company has the right to redeem the Series A Senior Preferred Stock, in whole or in part, at any time (subject to certain limitations on partial redemptions). The Redemption Price for each share of Series A Senior Preferred Stock is equal to the stated value subject to certain price adjustments depending on when such optional redemption takes place, if at all. The Series A Senior Preferred Stock is perpetual and is not mandatorily redeemable at the option of the holders, except upon the occurrence of a Mandatory Redemption Event. Upon the occurrence of a Mandatory Redemption Event, to the extent not prohibited by law, the Company is required to redeem all Series A Senior Preferred Stock, in cash, at a price per share equal to the then applicable Redemption Price. Because the Series A Senior Preferred Stock is mandatorily redeemable contingent on certain events outside the Company’s control, such as a change in control, the Series A Senior Preferred Stock is classified as mezzanine equity in the Company's consolidated balance sheets. Based on the Company’s assessment of the conditions which would trigger the redemption of the Series A Senior Preferred Stock, the Company has determined that the Series A Senior Preferred Stock is neither currently redeemable nor probable of becoming redeemable. Because the Series A Senior Preferred Stock is classified as mezzanine equity and is not considered redeemable or probable of becoming redeemable, the paid in-kind dividends that are added to the stated value do not impact the carrying value of the Series A Senior Preferred Stock in the Company’s consolidated balance sheets. Should the Series A Senior Preferred Stock become probable of becoming redeemable, the Company will recognize changes in the redemption value of the Series A Senior Preferred Stock immediately as they occur and adjust the carrying amount accordingly at the end of each reporting period. As of December 31, 2022, the redemption value of the Series A Senior Preferred Stock was $182.9 million, which is the stated value. If an Event of Noncompliance occurs, then the holders of a majority of the then outstanding shares of Series A Senior Preferred Stock (the “Majority Holders”) have the right to demand that the Company engage in a sale/refinancing process to consummate a Forced Transaction. A Forced Transaction includes a refinancing of the Series A Senior Preferred Stock or a sale of the Company. Upon consummation of any Forced Transaction, to the extent not prohibited by law, the Company is required to redeem all Series A Senior Preferred Stock, in cash, at a price per share equal to the then applicable Redemption Price. Holders of shares of Series A Senior Preferred Stock have no voting rights with respect to the Series A Senior Preferred Stock except as set forth in the Certificate of Designation, other documents entered into in connection with the Purchase Agreement and the transactions contemplated thereby, or as otherwise required by law. For so long as any Series A Senior Preferred Stock is outstanding, the Company is prohibited from taking certain actions without the prior consent of the Majority Holders as set forth in the Certificate of Designation which include: issuing equity securities ranking senior to or pari passu with the Series A Senior Preferred Stock, incurring indebtedness or liens, engaging in affiliate transactions, making restricted payments, consummating certain investments or asset dispositions, consummating a change of control transaction unless the Series A Senior Preferred Stock is redeemed in full, altering the Company’s organizational documents, and making material changes to the nature of the Company’s business. Holders of Series A Senior Preferred Stock, voting as a separate class, have the right to designate and elect one director to serve on the Company’s board of directors until such time after the Refinancing Date that (i) as of any applicable fiscal quarter end, the Company’s trailing 12-month Consolidated Adjusted EBITDA (as defined in the Certificate of Designation) exceeds $100 million, or (ii) the Lead Purchaser ceases to hold at least 50.1% of the Series A Senior Preferred Stock held by it as of the Refinancing Date. 2022 Warrants In connection with the Preferred Stock Financing, the Company agreed to issue to the preferred stockholders the Series I Warrants entitling the holders thereof to purchase 5.2 million shares of the Company's common stock at an exercise price equal to $3.00 per share, exercisable for 5 years from the Refinancing Date; and the Series II Warrants entitling holders thereof to purchase 6.3 million shares of the Company's common stock, at an exercise price equal to $0.01 per share, exercisable for 5 years from the Refinancing Date (collectively, the "2022 Warrants"). Such number of shares of common stock purchasable pursuant to the 2022 Warrant Agreement (the "2022 Warrant Shares") and related exercise prices may be adjusted from time to time under certain scenarios as set forth in the 2022 Warrant Agreement, which relate to potential changes in the Company's capital structure. The 2022 Warrants are classified as equity instruments and were initially recorded at an amount equal to the proceeds received from the Preferred Stock Financing allocated among the Series A Senior Preferred Stock, the Series I Warrants, and the Series II Warrants based upon their relative fair values. Of the gross proceeds, $5.1 million was allocated to the Series I Warrants and $15.2 million was allocated to the Series II Warrants. The Company recognized total issuance costs and original issue discount of approximately $0.2 million and $0.5 million related to the Series I Warrants and Series II Warrants, respectively. The following table reflects the components of proceeds related to the 2022 Warrants (in thousands): Series I Warrants Series II Warrants Total Gross proceeds allocated to 2022 Warrants $ 5,101 $ 15,232 $ 20,333 Less: original issue discount (51) (152) (203) Less: issuance costs (102) (303) (405) Net proceeds received from issuance of 2022 Warrants $ 4,948 $ 14,777 $ 19,725 Class A common stock The Company is authorized to issue 470.0 million shares of Class A common stock with a par value of $0.0001 per share. Holders of the Company’s Class A common stock are entitled to one vote for each share on each matter on which they are entitled to vote. At December 31, 2022, there were 207.5 million shares of Class A common stock issued and 198.4 million shares outstanding. As a result of the recapitalization associated with the Business Combination, shares are reflected as if they were issued and outstanding as of the earliest reported period to reflect the new capital structure. At the time of the Business Combination, stockholders of Wilco Holdco, Inc. received 130.3 million shares of the Company’s Class A common stock, par value $0.0001 per share, for the outstanding shares of Wilco Holdco common stock, par value $0.01 per share, that such stockholders owned. Upon distribution of shares to holders of unvested Incentive Common Units granted prior to the Business Combination under the Wilco Acquisition, LP 2016 Equity Incentive Plan, 2.0 million of these shares were restricted subject to vesting requirements, resulting in total unrestricted shares of 128.3 million and an exchange ratio of 136.7 unrestricted shares of ATI Physical Therapy, Inc. for every previously outstanding Wilco Holdco share. As of December 31, 2022, shares of Class A common stock reserved for potential future issuance, on an as-if converted basis, were as follows (in thousands): December 31, 2022 Shares available for grant under the 2021 Plan 10,862 2021 Plan share-based awards outstanding 9,687 Earnout Shares reserved 15,000 2022 Warrants outstanding 11,498 IPO Warrants outstanding 9,867 Vesting Shares reserved (1) 8,625 Restricted shares (1,2) 402 Total shares of common stock reserved 65,941 (1) Represents shares of Class A common stock legally issued, but not outstanding, as of December 31, 2022. (2) Represents a portion of the 2.0 million restricted shares distributed following the Business Combination to holders of unvested Incentive Common Units under the Wilco Acquisition, LP 2016 Equity Incentive Plan. Treasury stock During the year ended December 31, 2022, the Company net settled 0.05 million shares of its Class A common stock related to employee tax withholding obligations associated with the Company's share-based compensation program. These shares are reflected at cost as treasury stock in the consolidated financial statements. As of December 31, 2022, there were 0.08 million shares of treasury stock totaling $0.1 million recognized in the consolidated balance sheets.

Wilco Holdco Redeemable Preferr

Wilco Holdco Redeemable Preferred Stock	12 Months Ended
Wilco Holdco Redeemable Preferred Stock	Dec. 31, 2022
Equity [Abstract]
Wilco Holdco Redeemable Preferred Stock	Wilco Holdco Redeemable Preferred Stock On May 10, 2016, Wilco Holdco, Inc. issued shares of Series A Preferred Stock (the “Wilco Holdco preferred stock”) for a total consideration value of $98.0 million. Prior to the Business Combination, the Wilco Holdco preferred stock was a class of equity that had priority over the Common Stock with respect to distribution rights, liquidation rights and dividend rights. The Wilco Holdco preferred stockholders, from and after issuance, were entitled to cumulative preferred dividends at an annual rate per share equal to 10.25% of the original issue price. The dividend rate of the Wilco Holdco preferred stock increased by 0.25% at the end of each fiscal quarter beginning after the second anniversary of the issuance of the Wilco Holdco preferred stock. Based on the terms of the Wilco Holdco preferred stockholder agreement, Wilco Holdco, Inc. was required to redeem all outstanding shares of preferred stock upon the occurrence of certain events, such as those related to full repayment of the 2016 first and second lien credit agreements or a deemed liquidating event. Based on these redemption requirements, the Wilco Holdco preferred stock was classified as debt (redeemable preferred stock) in the Company’s historical consolidated balance sheets. Cumulative dividends related to the Wilco Holdco preferred stock were accrued as preferred dividends that increased the balance of the redeemable preferred stock on the Company’s consolidated balance sheets and were recognized as interest expense on redeemable preferred stock in the Company’s consolidated statements of operations. For the years ended December 31, 2021 and 2020, the Company incurred cumulative preferred dividends related to the preferred stock of $10.1 million and $19.0 million, respectively. No dividends were paid related to the preferred stock. In connection with the Business Combination, holders of the outstanding shares of Wilco Holdco Series A Preferred Stock received a proportionate share of $59.0 million and 12.8 million shares of Class A common stock based on the settlement terms in the Merger Agreement. During 2021, the Company recorded a loss on settlement of redeemable preferred stock in the consolidated statements of operations of $14.0 million based on the value of the cash and equity provided to preferred stockholders in relation to the outstanding redeemable preferred stock liability. As a result of the Business Combination, the balance of redeemable preferred stock was fully settled.

IPO Warrant Liability

IPO Warrant Liability	12 Months Ended
IPO Warrant Liability	Dec. 31, 2022
Other Liabilities Disclosure [Abstract]
IPO Warrant Liability	IPO Warrant Liability The Company has outstanding Public Warrants to purchase an aggregate of 6.9 million shares of the Company’s Class A common stock at an exercise price of $11.50 per share and outstanding Private Placement Warrants to purchase an aggregate of 3.0 million shares of the Company's Class A common stock at an exercise price of $11.50 per share. There were no IPO Warrants exercised during the year ended December 31, 2022 . The Company accounts for its outstanding IPO Warrants in accordance with the guidance contained in ASC 815-40, Derivatives and Hedging - Contracts on an Entity’s Own Equity, and determined that the IPO Warrants do not meet the criteria for equity treatment thereunder. As such, each IPO Warrant must be recorded as a liability and is subject to re-measurement at each balance sheet date. Refer to Note 15 - Fair Value Measurements for further details. Changes in fair value are recognized in change in fair value of warrant liability in the Company’s consolidated statements of operations. The following table presents the change in the fair value of Private Placement Warrants that is recognized in change in fair value of warrant liability in the consolidated statements of operations for the periods indicated below (in thousands): Year Ended December 31, 2022 December 31, 2021 Fair value, beginning of period (1) $ 1,305 $ 8,099 Changes in fair value (1) (1,276) (6,794) Fair value, end of period $ 29 $ 1,305 (1) The year ended December 31, 2021 represents changes in fair value from the Closing Date of the Business Combination, which is when the liabilities were established. The following table presents the changes in the fair value of the Public Warrants that is recognized in change in fair value of warrant liability in the consolidated statements of operations for the periods indicated below (in thousands): Year Ended December 31, 2022 December 31, 2021 Fair value, beginning of period (1) $ 3,036 $ 18,837 Changes in fair value (1) (2,967) (15,801) Fair value, end of period $ 69 $ 3,036 (1) The year ended December 31, 2021 represents changes in fair value from the Closing Date of the Business Combination, which is when the liabilities were established. Each Public Warrant entitles the holder to purchase one share of Class A common stock at an exercise price of $11.50 per share, subject to adjustment. The Public Warrants became exercisable 30 days after the completion of the Business Combination, subject to certain conditions, including that the Company maintains an effective registration statement under the Securities Act covering the Class A common stock issuable upon exercise of the Public Warrants. The Public Warrants will expire five years after the completion of the Business Combination or earlier upon redemption or liquidation. The Company may call the Public Warrants for redemption for cash or for Class A common stock under certain circumstances. The Private Placement Warrants are identical to the Public Warrants, except that (i) the Private Placement Warrants and the Class A common stock issuable upon exercise of the Private Placement Warrants were not transferable, assignable or salable until 30 days after the completion of the Business Combination, subject to certain limited exceptions, (ii) the Private Placement Warrants are non-redeemable (except under certain circumstances) so long as they are held by the initial purchasers or such purchasers’ permitted transferees, (iii) the Private Placement Warrants may be exercised by the holders on a cashless basis, and (iv) the Private Placement Warrants and the Class A common stock issuable upon exercise of the Private Placement Warrants are entitled to registration rights. If the Private Placement Warrants are held by someone other than the initial stockholders or their permitted transferees, the Private Placement Warrants will be redeemable by the Company in all redemption scenarios and exercisable by such holders on the same basis as the Public Warrants. The exercise price and number of Class A common stock issuable upon exercise of the IPO Warrants may be adjusted in certain circumstances including in the event of a stock dividend, recapitalization, reorganization, merger or consolidation.

Contingent Common Shares Liabil

Contingent Common Shares Liability	12 Months Ended
Contingent Common Shares Liability	Dec. 31, 2022
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Contingent Common Shares Liability	Contingent Common Shares Liability Earnout Shares Subject to the terms and conditions of the Merger Agreement, certain stockholders of Wilco Holdco, Inc. were provided the contingent right to receive, in the aggregate, up to 15.0 million shares of Class A common stock if, from the closing of the Business Combination until the 10 th anniversary thereof, the dollar volume-weighted average price (“VWAP”) of Class A common stock exceeds certain thresholds: – The first issuance of 5.0 million Earnout Shares will occur if the VWAP exceeds $12.00 for any 5 trading days within any consecutive 10 trading day period. – The second issuance of 5.0 million Earnout Shares will occur if the VWAP exceeds $14.00 for any 5 trading days within any consecutive 10 trading day period. – The third issuance of 5.0 million Earnout Shares will occur if the VWAP exceeds $16.00 for any 5 trading days within any consecutive 10 trading day period. The Earnout Shares are subject to acceleration in the event of a sale or other change in control if the holders of Class A common stock would receive a per share price in excess of the applicable Earnout Shares price target. The Company accounts for the potential Earnout Shares as a liability in accordance with the guidance in ASC 480, Distinguishing Liabilities from Equity , and ASC 815, Derivatives and Hedging, and is subject to re-measurement at each balance sheet date. Changes in fair value are recognized in the Company’s consolidated statements of operations. As of December 31, 2022, no Earnout Shares have been issued as none of the corresponding share price thresholds have been met. The following table presents the changes in the fair value of the Earnout Shares that is recognized in change in fair value of contingent common shares liability in the consolidated statements of operations for the periods indicated below (in thousands): Year Ended December 31, 2022 December 31, 2021 Fair value, beginning of period (1) $ 28,800 $ 140,000 Changes in fair value (1) (27,000) (111,200) Fair value, end of period $ 1,800 $ 28,800 (1) The year ended December 31, 2021 represents changes in fair value from the Closing Date of the Business Combination, which is when the liabilities were established. Refer to Note 15 - Fair Value Measurements for further details. Vesting Shares Subject to the terms and conditions of the Sponsor Letter Agreement that was executed in connection with the Merger Agreement, 8.6 million shares of Class F common stock of FAII outstanding immediately prior to the Business Combination converted to potential Class A common shares and became subject to vesting and forfeiture provisions. The Vesting Shares vest in three equal tranches of 2.9 million shares each if the VWAP of Class A common stock exceeds certain thresholds within 10 years of the Closing Date: – The first issuance of 2.9 million Vesting Shares will occur if the VWAP exceeds $12.00 for any 5 trading days within any consecutive 10 trading day period. – The second issuance of 2.9 million Vesting Shares will occur if the VWAP exceeds $14.00 for any 5 trading days within any consecutive 10 trading day period. – The third issuance of 2.9 million Vesting Shares will occur if the VWAP exceeds $16.00 for any 5 trading days within any consecutive 10 trading day period. The Vesting Shares are subject to acceleration in the event of a sale or other change in control if the holders of Class A common stock would receive a per share price in excess of the applicable Vesting Shares price target. The Company accounts for the Vesting Shares as a liability in accordance with the guidance in ASC 480, Distinguishing Liabilities from Equity , and ASC 815, Derivatives and Hedging, and is subject to re-measurement at each balance sheet date. Changes in fair value are recognized in the Company’s consolidated statements of operations. As of December 31, 2022, no Vesting Shares are outstanding as none of the corresponding share price thresholds have been met. The following table presents the changes in the fair value of the Vesting Shares that is recognized in change in fair value of contingent common shares liability in the consolidated statements of operations for the periods indicated below (in thousands): Year Ended December 31, 2022 December 31, 2021 Fair value, beginning of period (1) $ 16,560 $ 80,500 Changes in fair value (1) (15,525) (63,940) Fair value, end of period $ 1,035 $ 16,560 (1) The year ended December 31, 2021 represents changes in fair value from the Closing Date of the Business Combination, which is when the liabilities were established. Refer to Note 15 - Fair Value Measurements for further details.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
Fair Value Measurements	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The Company determines fair value measurements used in its consolidated financial statements based upon the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Fair value is estimated by applying the following hierarchy, which prioritizes the inputs used to measure fair value into three levels, with Level 1 having the highest priority and Level 3 having the lowest. • Level 1: Observable inputs, which include unadjusted quoted prices in active markets for identical instruments. • Level 2: Observable inputs other than Level 1 inputs, such as quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the instruments. • Level 3: Unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions, such as valuations derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable. As of December 31, 2022 and December 31, 2021 , respectively, the recorded values of cash and cash equivalents, accounts receivable, other current assets, accounts payable, accrued expenses and deferred revenue approximate their fair values due to the short-term nature of these items. Money market funds categorized in Level 1 of the fair value hierarchy are measured at fair value based on quoted market prices. As of December 31, 2022, the fair value of money market fund investments i ncluded in cash and cash equivalents was $30.0 million . The Company's Senior Secured Term Loan and Revolving Loans are Level 2 fair value measures which have variable interest rates and, a s of December 31, 2022, the recorded amounts approximate fair value. The Company utilizes the market approach valuation technique based on interest rates and credit data that are currently available to the Company for issuance of debt with similar terms or maturities. Fair value measurement of share-based financial liabilities The Company determined the fair value of the Public Warrant liability using Level 1 inputs. The Company determined the fair value of the Private Placement Warrant liability using the price of the Public Warrants as a Level 2 input. The Company determined the fair value of the Earnout Shares liability and Vesting Shares liability using Level 3 inpu ts. The contingent common shares contain specific market conditions to determine whether the shares vest based on the Company’s common stock price over a specified measurement period. Given the path-dependent nature of the requirement in which the shares are earned, a Monte-Carlo simulation was used to estimate the fair value of the liability. The Company’s common stock price was simulated to each measurement period based on the above methodology. In each iteration, the simulated stock price was compared to the conditions under which the shares vest. In iterations where the stock price corresponded to shares vesting, the future value of the contingent common shares was discounted back to present value. The fair value of the liability was estimated based on the average of all iterations of the simulation. Inherent in a Monte-Carlo valuation model are assumptions related to expected stock-price volatility, expected term, risk-free interest rate and dividend yield. The Company estimates the volatility based on the historical volatility of certain guideline companies as of the valuation date. The risk-free interest rate is based on the U.S. Treasury zero-coupon yield curve on the grant date for a maturity similar to the expected term of the Earnout Shares and Vesting Shares. The dividend yield percentage is zero based on the Company's current expectations related to the payment of dividends during the expected term of the Earnout Shares or Vesting Shares. The key inputs into the Monte-Carlo option pricing model were as follows as of December 31, 2022 and December 31, 2021 for the respective Level 3 instruments : Earnout Shares Vesting Shares December 31, 2022 December 31, 2021 December 31, 2022 December 31, 2021 Risk-free interest rate 3.88% 1.50% 3.88% 1.50% Volatility 74.60% 44.86% 74.60% 44.86% Dividend yield —% —% —% —% Expected term (years) 8.5 9.5 8.5 9.5 Share price $0.31 $3.39 $0.31 $3.39 Refer to Note 14 - Contingent Common Shares Liability for further details on the change in fair value of the Earnout Shares and Vesting Shares. Fair value measurement of interest rate derivative instruments The Company is exposed to interest rate variability with regard to its existing variable-rate debt instrument, which exposure primarily relates to movements in various interest rates, such as SOFR. The Company utilizes interest rate cap derivative instruments for purposes of hedging exposures related to such variable-rate cash payments. The Company's interest rate caps are designated as cash flow hedging instruments. The Company records derivatives on the balance sheet at fair value, which represents the estimated amounts it would receive or pay upon termination of the derivative prior to the scheduled expiration date. The fair value is derived from model-driven information based on observable Level 2 inputs, such as LIBOR or SOFR forward rates. For derivatives designated and that qualify as cash flow hedges of interest rate risk, the gain or loss on the derivative is recorded in accumulated other comprehensive income and subsequently reclassified into interest expense in the same period(s) during which the hedged transaction affects earnings. As discussed in Note 2 – Basis of Presentation and Summary of Significant Accounting Policies , the Company has a derivative instrument for which the interest rate is indexed to LIBOR. During the period ended March 31, 2022, the Company modified the reference rate index on its hedged items from LIBOR to SOFR. The Company elected to apply the hedge accounting expedients under ASC Topic 848, Reference Rate Reform , related to probability and the assessments of effectiveness for future cash flows to assume that the index upon which future hedged transactions will be based matches the index on the corresponding derivative, which is LIBOR. As of December 31, 2022 , the Company continues to apply the hedge accounting expedients and does not anticipate this guidance will have a material impact on its consolidated financial statements. The following table presents the activity of cash flow hedges included in accumulated other comprehensive income (loss) for the years ended December 31, 2022 and 2021, respectively (in thousands): Cash Flow Hedges Balance as of December 31, 2021 $ 28 Unrealized gain recognized in other comprehensive income before reclassifications 8,310 Reclassification to interest expense, net (3,439) Balance as of December 31, 2022 $ 4,899 Balance as of December 31, 2020 $ (1,907) Unrealized gain recognized in other comprehensive income before reclassifications 490 Reclassification to interest expense, net 1,445 Balance as of December 31, 2021 $ 28 The following table presents the fair value of derivative assets and liabilities within the consolidated balance sheets as of December 31, 2022 and December 31, 2021 (in thousands): December 31, 2022 December 31, 2021 Assets Liabilities Assets Liabilities Derivatives designated as cash flow hedging instruments: Other current assets $ 5,028 $ — $ — $ — Other non-current assets — — 277 — Accrued expenses and other liabilities — — — 288 Other non-current liabilities — 73 — —

Income Taxes

Income Taxes	12 Months Ended
Income Taxes	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company's (loss) income before taxes consists of only domestic operations. The details of the Company's income tax (benefit) expense for the years ended December 31, 2022, 2021 and 2020 are as follows (in thousands): 2022 2021 2020 Current: Federal $ 6 $ — $ — State 37 128 251 Total current 43 128 251 Deferred: Federal (37,634) (60,002) 3,514 State (10,939) (11,086) (1,700) Total deferred (48,573) (71,088) 1,814 Total income tax (benefit) expense $ (48,530) $ (70,960) $ 2,065 The effective tax rate for the years ended December 31, 2022, 2021 and 2020 was 9.0%, 8.3% and (62.5)%, respectively. The Company's effective income tax rate varies from the federal statutory rate due to various items, such as state income taxes, valuation allowances and nondeductible items such as interest expense on redeemable preferred stock, fair value adjustments related to liability-classified share-based instruments and impairment charges. The differences between the federal tax rate and the Company's effective tax rate for the years ended December 31, 2022, 2021 and 2020 are as follows (in thousands): 2022 2021 2020 Federal income tax benefit at statutory rate $ (113,731) 21.0 % $ (179,128) 21.0 % $ (694) 21.0 % State income tax (benefit) expense, net of federal tax benefit (16,827) 3.1 % (25,814) 3.0 % 1,248 (37.8) % Change in state tax rate 5 — % 34 — % (2,551) 77.1 % Prior period adjustments and other 167 — % 1,515 (0.2) % (105) 3.2 % Valuation allowance 31,595 (5.8) % 35,731 (4.2) % (981) 29.7 % Interest expense on redeemable preferred stock — — % 2,118 (0.2) % 3,997 (120.9) % Changes in fair value of warrant liability and contingent common shares liability (9,821) 1.8 % (41,524) 4.9 % — — % Goodwill impairment charges 59,893 (11.1) % 132,447 (15.5) % — — % Other permanent differences, net 189 — % 3,661 (0.5) % 1,151 (34.8) % Total income tax (benefit) expense $ (48,530) 9.0 % $ (70,960) 8.3 % $ 2,065 (62.5) % Deferred income taxes have been provided on temporary differences, which consist of the following at December 31, 2022 and 2021 (in thousands): 2022 2021 Deferred income tax assets: Accrued liabilities $ 7,112 $ 10,420 Provision for bad debt 11,828 12,530 Operating lease liabilities 64,288 74,115 Acquisition and transaction costs 3,186 3,770 Net operating losses 104,419 82,304 Interest expense 43,323 33,163 Other deferred tax assets 6,335 4,798 Total gross deferred income tax assets 240,491 221,100 Valuation allowance (89,907) (58,312) Total gross deferred income tax assets, net of valuation allowance 150,584 162,788 Deferred income tax liabilities: Goodwill 26,251 26,563 Trade name/trademark 66,445 114,451 Operating lease right-of-use assets 54,360 63,252 Depreciation 20,039 22,089 Other deferred tax liabilities 2,375 3,892 Total gross deferred income tax liabilities 169,470 230,247 Net deferred income tax liabilities $ 18,886 $ 67,459 Deferred tax assets include federal net operating losses of $68.9 million and $49.8 million at December 31, 2022 and 2021, respectively, and state net operating losses of $35.5 million and $32.5 million at December 31, 2022 and 2021, respectively. Deferred tax assets are expected to be used in the reduction of taxable earnings of future tax years unless it is determined they are not more likely than not to be realized based on the weight of available evidence. The earliest net operating loss will expire by statute in 2023 for state net operating losses, and in 2036 for federal net operating losses. In evaluating the Company's ability to recover deferred income tax assets, all available positive and negative evidence is considered, including scheduled reversal of deferred tax liabilities, operating results and forecasts of future taxable income in each of the jurisdictions in which the Company operates. As of December 31, 2022, the Company determined that a significant portion of its federal and state net operating loss carryforwards with definite and certain indefinite carryforward periods and certain deferred tax assets were not more likely than not to be realized based on the weight of available evidence. As a result, the Company recorded an increase of $25.8 million to its valuation allowance related to federal net operating loss and interest expense carryforwards and an increase of $5.8 million to its valuation allowance related to state net operating loss carryforwards and certain deferred tax assets. These amounts were recorded during the year ended December 31, 2022 in income tax (benefit) expense in the consolidated statements of operations. As of December 31, 2021, the Company determined that a significant portion of its federal and state net operating loss carryforwards with definite carryforward periods and certain deferred tax assets were not more likely than not to be realized based on the weight of available evidence. As a result, the Company recorded an increase of $22.5 million to its valuation allowance related to federal net operating loss carryforwards and an increase of $13.3 million to its valuation allowance related to state net operating loss carryforwards and certain deferred tax assets. These amounts were recorded during the year ended December 31, 2021 in income tax (benefit) expense in the consolidated statements of operations. For the year ended December 31, 2020, the Company reached the conclusion that it was more likely than not that the Company’s federal and certain state deferred income tax assets were expected to be realized, and the Company maintained a valuation allowance mainly related to certain state net operating losses. The Company is routinely audited by the tax authorities in various U.S. states and is currently not subject to examination. The statute remains open for most state jurisdictions for periods beginning in 2018. For federal tax purposes, tax years through 2018 are closed for examination by the Internal Revenue Service. Any interest and penalties related to the tax uncertainties are recorded in income tax (benefit) expense. As reflected in the following table (in thousands), the Company had an uncertain tax position related to the tax treatment of tenant improvement allowances. Due to the Company's net operating loss position, there were no accrued interest and penalties related to the unrecognized tax benefits in any year. Our gross unrecognized tax benefits were reduced by $3.0 million during the year ended December 31, 2021 due to tax filings. Of the gross unrecognized tax benefits, none were recognized as liabilities in the consolidated balance sheets in any year due to tax attribute carryforwards available to offset a potential tax liability. 2022 2021 2020 Balance at beginning of period $ — $ 3,027 $ 2,341 Increases for positions taken during the year — — 686 Decreases for positions taken in prior years — (3,027) — Balance at end of period $ — $ — $ 3,027

Leases

Leases	12 Months Ended
Leases	Dec. 31, 2022
Leases [Abstract]
Leases	Leases The Company leases various facilities and office equipment for its physical therapy operations and administrative support functions under operating leases. The Company’s initial operating lease terms are generally between 7 and 10 years, and typically contain options to renew for varying terms. Right-of-use ("ROU") assets and lease liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. The amortization of operating lease ROU assets and the accretion of operating lease liabilities are reported together as fixed lease expense. The fixed lease expense is recognized on a straight-line basis over the life of the lease. If the ROU asset has been impaired, lease expense is no longer recognized on a straight-line basis. The lease liability continues to amortize using the effective interest method, while the ROU asset is subsequently amortized on a straight-line basis. Refer to Note 2 - Basis of Presentation and Summary of Significant Accounting Policies for more information about the Company's lease accounting policies and ASC 842 adoption. Lease costs are included as components of cost of services and selling, general and administrative expenses on the consolidated statements of operations. Lease charges related to ROU asset impairments are included in goodwill, intangible and other asset impairment charges on the consolidated statements of operations. Lease costs incurred by lease type were as follows for the periods indicated below (in thousands): Year Ended December 31, 2022 December 31, 2021 December 31, 2020 Lease cost Operating lease cost (1) $ 69,533 $ 65,555 $ 67,279 Variable lease cost (2) 20,951 20,045 18,689 Total lease cost (3) $ 90,484 $ 85,600 $ 85,968 (1) Includes ROU asset impairment charges of $2.6 million and $1.2 million for the years ended December 31, 2022 and 2021, respectively. (2) Includes short term lease costs, which are immaterial . (3) Sublease income was immaterial . During the year ended December 31, 2020, the Company terminated certain lease agreements primarily related to corporate facilities no longer in use. These terminations resulted in net charges of $4.3 million, comprised of $3.9 million in loss on lease terminations and $0.4 million in other costs associated with the terminations. The charges are recorded in selling, general and administrative expenses in the Company's consolidated statements of operations. The Company paid approximately $4.6 million related to these terminations during the year ended December 31, 2021. During the years ended December 31, 2022 and 2021, the Company modified the lease terms for a significant number of its real estate leases, primarily related to lease term extensions and renewals in the normal course of business. Modifications during the years ended December 31, 2022 and 2021 resulted in an increase to the Company’s operating lease ROU assets and operating lease liabilities of approximately $13.7 million and $18.4 million, respectively. Other supplemental quantitative disclosures were as follows for the periods indicated below (in thousands): Year Ended December 31, 2022 December 31, 2021 December 31, 2020 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 72,440 $ 65,678 $ 61,993 Cash payments related to lease terminations $ — $ 4,570 $ — Right-of-use assets obtained in exchange for new operating lease liabilities $ 9,688 $ 28,759 $ 14,067 Average lease terms and discount rates as of December 31, 2022 and December 31, 2021 were as follows: December 31, 2022 December 31, 2021 Weighted-average remaining lease term: Operating leases 5.9 years 6.4 years Weighted-average discount rate: Operating leases 6.9% 6.5% Estimated undiscounted future lease payments under non-cancellable operating leases, along with a reconciliation of the undiscounted cash flows to operating lease liabilities, respectively, at December 31, 2022 were as follows (in thousands): Year Amount (1) 2023 $ 64,066 2024 61,885 2025 52,459 2026 46,069 2027 35,108 Thereafter 68,006 Total undiscounted future cash flows 327,593 Less: Imputed Interest (61,493) Present value of future cash flows $ 266,100 Presentation on Balance Sheet Current $ 47,676 Non-current $ 218,424 (1) Excludes $0.7 million of current portion of operating lease liabilities and $1.7 million of operating lease liabilities, respectively, reclassified as held for sale as of December 31, 2022. Refer to Note 3 - Business Combinations and Divestitures for additional information.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies The Company has contractual commitments that are not required to be recognized in the consolidated financial statements related to cloud computing and telecommunication services agreements. As of December 31, 2022, minimum amounts due under these agreements are approximately $7.2 million through December of 2024 subject to customary business terms and conditions. From time to time, the Company is a party to legal proceedings, governmental audits and investigations that arise in the ordinary course of business. Management is not aware of any legal proceedings, governmental audits and investigations of which the outcome is probable to have a material adverse effect on the Company’s results of operations, cash flows or financial condition. The outcome of any litigation and claims against the Company cannot be predicted with certainty, and the resolution of current or future claims could materially affect our future results of operations, cash flows or financial condition. During 2022, the Company engaged in discussions with a payor regarding a billing dispute related to certain historical claims. Management believed, based on discussions with its legal counsel, that the Company had meritorious defenses against such unasserted claim. However, based on the progress of settlement discussions to avoid the cost of potential litigation, the Company recorded a charge for a net settlement liability related to the billing dispute of $3.0 million, which is included in selling, general and administrative expenses in its consolidated statements of operations. As of December 31, 2022, the liability has been fully settled. Section 205 proceeding On March 2, 2023, we filed a petition in the Delaware Court of Chancery (the "Court of Chancery") pursuant to Section 205 of the Delaware General Corporation Law ("DGCL"), seeking validation of an amendment to our certificate of incorporation increasing the authorized shares of our Class A Common Stock (as further described below) and the shares issued pursuant thereto. At a special meeting of the stockholders of the Company held on June 15, 2021 (the “Special Meeting”), a majority of the then-outstanding shares of the Company’s Class A Common Stock and Class F Common Stock, voting together as a single class, voted to approve the Company’s Second Amended and Restated Certificate of Incorporation, which, among other things, increased the authorized shares of the Company’s Class A Common Stock from 200,000,000 shares to 450,000,000 shares (the “Class A Increase Amendment”). Notwithstanding the fact that the proxy statement relating to the Special Meeting did not disclose that a separate vote of the Class A Common Stock was required, a majority of the then-outstanding shares of Class A Common Stock voted in favor of the Class A Increase Amendment. A recent decision of the Court of Chancery has created uncertainty regarding the validity of the Class A Increase Amendment and whether a separate vote of the majority of the then-outstanding shares of Class A Common Stock would have been required under Section 242(b)(2) of the DGCL. The Company continues to believe that a separate vote of Class A Common Stock was not required to approve the Class A Increase Amendment. However, in light of the recent Court of Chancery decision, the Company filed a petition in the Court of Chancery pursuant to Section 205 of the DGCL seeking validation of the Class A Increase Amendment and the shares issued pursuant thereto to resolve any uncertainty with respect to those matters. Section 205 of the DGCL permits the Court of Chancery, in its discretion, to validate potentially defective corporate acts and stock after considering a variety of factors. While the Company believes that a separate vote of Class A Common Stock was not required to approve the Class A Increase Amendment at the Special Meeting, and therefore that all of the currently outstanding shares of Class A Common Stock of the Company are validly issued, if the Company is not successful in the Section 205 proceeding, the uncertainty with respect to the Company’s capitalization resulting from the Court of Chancery’s decision referenced above could have a material adverse effect on the Company, including its ability to complete financing transactions, until the underlying issues are definitively resolved. On March 3, 2023, the Court of Chancery granted the motion to expedite and set a hearing date for the petition to be heard. The hearing has been set for March 17, 2023. Stockholder class action complaints On August 16, 2021, two purported ATI stockholders, Kevin Burbige and Ziyang Nie, filed a putative class action complaint in the U.S. District Court for the Northern District of Illinois against ATI, Labeed Diab, Joe Jordan, and Drew McKnight (collectively, the “ATI Individual Defendants”), and Joshua Pack, Marc Furstein, Leslee Cowen, Aaron Hood, Carmen Policy, Rakefet Russak-Aminoach, and Sunil Gulati (collectively, the “FVAC Defendants”). On October 7, 2021, another purported ATI stockholder, City of Melbourne Firefighters' Retirement System ("City of Melbourne"), filed a nearly identical putative class action complaint in the U.S. District Court for the Northern District of Illinois against ATI, the ATI Individual Defendants, and the FVAC Defendants. On November 18, 2021, the court consolidated the cases and appointed The Phoenix Insurance Company Ltd. and The Phoenix Pension & Provident Funds as lead plaintiffs (together, “Lead Plaintiffs”). On February 8, 2022, Lead Plaintiffs filed a consolidated amended complaint against ATI, the ATI Individual Defendants, and the FVAC Defendants, which asserts claims against (i) ATI and the ATI Individual Defendants under Section 10(b) of the Exchange Act; (ii) the ATI Individual Defendants under Section 20(a) of the Exchange Act (in connection with the Section 10(b) claim); (iii) all defendants under Section 14(a) of the Exchange Act; and (iv) the ATI Individual Defendants and the FVAC Defendants under Section 20(a) of the Exchange Act (in connection with the Section 14(a) claim). Lead Plaintiffs purport to assert these claims on behalf of those ATI stockholders who purchased or otherwise acquired their ATI shares between February 22, 2021 and October 19, 2021, inclusive, and/or held FVAC Class A common shares as of May 24, 2021 and were eligible to vote at FVAC’s June 15, 2021 special meeting. The consolidated amended complaint generally alleges that the proxy materials for the FVAC/ATI merger, as well as other ATI disclosures (including the press release announcing ATI’s financial results for the first quarter of 2021), were false and misleading (and, thus, in violation of Sections 10(b) and 14(a) of the Exchange Act) because they failed to disclose that: (i) ATI was experiencing attrition among its physical therapists; (ii) ATI faced increasing competition for clinicians in the labor market; (iii) as a result, ATI faced difficulty retaining therapists and incurred increased labor costs; (iv) also as a result, ATI would open fewer new clinics; and (v) also as a result, the defendants’ positive statements about ATI’s business, operations, and prospects were materially misleading and/or lacked a reasonable basis. Lead Plaintiffs, on behalf of themselves and the putative class, seek money damages in an unspecified amount and costs and expenses, including attorneys’ and experts’ fees. On April 11, 2022, defendants filed motions to dismiss the consolidated amended complaint, which were fully briefed as of July 25, 2022 and remain pending. The Company has determined that potential liabilities related to the consolidated amended complaint are not considered probable or reasonably estimable at this time. On February 7, 2023, another purported ATI stockholder, Wendell Robinson, filed a putative class action complaint in the Court of Chancery of the State of Delaware against Fortress Acquisition Sponsor II, LLC, Andrew A. McKnight, Joshua A. Pack, Marc Furstein, Leslee Cowen, Aaron F. Hood, Carmen A. Policy, Rakefet Russak-Aminoach, Sunil Gulati, Daniel N. Bass, Micah B. Kaplan and Labeed Diab. The complaint asserts claims against: (i) Fortress Acquisition Sponsor II, LLC, Andrew A. McKnight, Joshua A. Pack, Marc Furstein, Leslee Cowen, Aaron F. Hood, Carmen A. Policy, Rafeket Russak-Aminoach, Sunil Gulati, Daniel N. Bass and Micah B. Kaplan for breach of fiduciary duty; and (ii) Labeed Diab for aiding and abetting breach of fiduciary duty. Plaintiff's allegations generally mirror those asserted in the federal stockholder class action described above, and Plaintiff further alleges that the alleged misrepresentations and omissions in the proxy materials for the FVAC/ATI merger prevented stockholders from making a fully informed decision on whether to approve the merger or have their shares redeemed. Defendants have not yet responded to the complaint. Stockholder derivative complaint Between December 1, 2021 and September 22, 2022, five purported ATI stockholders filed four derivative actions, purportedly on behalf of ATI, in the U.S. District Court for the Northern District of Illinois. On November 21, 2022, four of these stockholder plaintiffs, Vinay Kumar, Brendan Reginbald, Ziyang Nie and Julia Chang, filed a consolidated amended complaint against Labeed Diab, Joe Jordan, John Larsen, John Maldonado, Carmine Petrone, Christopher Krubert, Joanne Burns and James Parisi (collectively, the “Legacy ATI Defendants”), Drew McKnight, Joshua Pack, Aaron Hood, Carmen Policy, Marc Furstein, Leslee Cowen, Rafeket Russak-Aminoach, and Sunil Gulati (collectively, the “FVACII Individual Defendants”), and Fortress Acquisition Sponsor II, LLC and Fortress Investment Group LLC (together, the "Fortress Entity Defendants," and together with the FVACII Individual Defendants, the “FVACII Defendants”). The consolidated amended complaint asserts claims on behalf of ATI against: (i) the FVACII Defendants for breach of fiduciary duty; (ii) Fortress Acquisition Sponsor II, LLC and the Legacy ATI Defendants for aiding and abetting breach of fiduciary duty; (iii) Labeed Diab, Joe Jordan, and Drew McKnight for contribution under Section 21D of the Exchange Act; (iv) the FVACII Defendants under Section 14(a) of the Exchange Act; (v) the Legacy ATI Defendants for unjust enrichment; and (vi) all defendants for contribution and indemnification under Delaware law. Plaintiffs' allegations generally mirror those asserted in the stockholder class action described above. On January 20, 2023, defendants filed motions to dismiss the consolidated amended complaint, which remain pending. The Company has determined that potential liabilities related to the consolidated amended complaint are not considered probable or reasonably estimable at this time. Insurance coverage complaint On March 8, 2023, the Company filed a complaint against Federal Insurance Company, U.S. Specialty Insurance Company and other insurers titled ATI Physical Therapy, Inc. v. Federal Insurance Company et. al., Case No. N23C-03-074, in the Superior Court of the State of Delaware related to a coverage dispute and those certain insurers’ denial of coverage for the stockholder class action complaints and stockholder derivative complaint discussed above. The complaint asserts claims against Federal Insurance Company for breach of contract and bad faith, and claims for declaratory judgment as to Federal Insurance Company, U.S. Specialty Insurance Company, XL Specialty Insurance Company and the Company’s excess insurance carriers, seeking coverage for the stockholder class action complaints and stockholder derivative complaint. Regulatory matters On November 5, 2021, the Company received from the SEC a voluntary request for the production of documents relating to the earnings forecast and financial information referenced in the Company's July 26, 2021 Form 8-K and related matters. The Company received a subsequent request from the SEC for the production of additional documents related to the same matter on February 17, 2023. The Company is cooperating with the SEC in connection with this request. Indemnifications The Company has agreed to indemnify its current and former directors and executive officers for costs associated with any fees, expenses, judgments, fines and settlement amounts incurred by them in any action or proceeding to which any of them are, or are threatened to be, made a party by reason of their service as a director or officer. The Company maintains director and officer insurance coverage that would generally enable it to recover a portion of any amounts paid. The ultimate cost of current or potential future litigation may exceed the Company’s current insurance coverages and may have a material adverse impact on our results of operations, cash flows and financial condition. The Company also may be subject to indemnification obligations by law with respect to the actions of its employees under certain circumstances and in certain jurisdictions.

Loss per Share

Loss per Share	12 Months Ended
Loss per Share	Dec. 31, 2022
Earnings Per Share [Abstract]
Loss per Share	Loss per Share Basic loss per share is computed by dividing net loss by the weighted average number of common shares outstanding during the period. For the years ended December 31, 2021 and 2020, shares of Wilco Holdco preferred stock are treated as participating securities and therefore are included in computing earnings per common share using the two-class method. The two-class method is an earnings allocation formula that calculates basic and diluted net earnings per common share for each class of common stock separately based on dividends declared and participation rights in undistributed earnings as if the earnings for the year had been distributed. As the Wilco Holdco preferred stockholders do not participate in losses, for any periods with a net loss, there is no allocation to participating securities in the period. As such, no undistributed earnings or losses were allocated to the Wilco Holdco preferred shares for the years ended December 31, 2021 and 2020. As of the closing of the Business Combination, the Wilco Holdco preferred stock is no longer outstanding. For the year ended December 31, 2022, the income available to common stockholders is reduced by the amount of the cumulative dividend for the Series A Senior Preferred Stock that was issued as part of the 2022 Debt Refinancing. The calculation of both basic and diluted loss per share for the periods indicated below was as follows (in thousands, except per share data): Year Ended December 31, 2022 December 31, 2021 December 31, 2020 Basic and diluted loss per share: Net loss $ (493,047) $ (782,028) $ (298) Less: Net (loss) income attributable to non-controlling interests (668) (3,700) 5,073 Less: Series A Senior Preferred cumulative dividend 17,876 — — Loss available to common stockholders $ (510,255) $ (778,328) $ (5,371) Weighted average shares outstanding (1,2) 203,150 165,805 128,286 Basic and diluted loss per share $ (2.51) $ (4.69) $ (0.04) (1) The weighted-average number of shares outstanding in periods presented prior to the closing of the Business Combination has been retrospectively adjusted based on the exchange ratio established through the transaction. (2) Included within weighted average shares outstanding following the 2022 Debt Refinancing are common shares issuable upon the exercise of the Series II Warrants, as the Series II Warrants are exercisable at any time for nominal consideration. As such, the shares are considered to be outstanding for the purpose of calculating basic and diluted loss per share. For the periods presented, the following securities were not required to be included in the computation of diluted shares outstanding, as their impact would have been anti-dilutive. Figures presented are based on the number of underlying Class A common shares following the Business Combination (in thousands): Year Ended December 31, 2022 December 31, 2021 December 31, 2020 Series I Warrants 5,226 — — IPO Warrants 9,867 9,867 — Restricted shares (1) 402 1,323 — Stock options 5,313 775 — RSUs 4,200 404 — RSAs 175 448 — Total 25,183 12,817 — (1) Represents a portion of the 2.0 million restricted shares distributed following the Business Combination to holders of unvested Incentive Common Units under the Wilco Acquisition, LP 2016 Equity Incentive Plan. Refer to Note 10 - Share-Based Compensation for further details. 15.0 million Earnout Shares and 8.6 million Vesting Shares were excluded from the calculation of basic and diluted per share calculations as the vesting thresholds have not yet been met as of the end of the reporting period.

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
Schedule II - Valuation and Qualifying Accounts	Dec. 31, 2022
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Accounts	Schedule II - Valuation and Qualifying Accounts $ in thousands Balance at Beginning of Year Additions Deductions/ Adjustments Balance at Year ended December 31, 2022 Allowance for doubtful accounts (1) 53,533 13,869 (19,782) 47,620 Valuation allowance for deferred tax assets (2) 58,312 31,595 — 89,907 Year ended December 31, 2021 Allowance for doubtful accounts (1) 69,693 16,369 (32,529) 53,533 Valuation allowance for deferred tax assets (2) 22,581 35,731 — 58,312 Year ended December 31, 2020 Allowance for doubtful accounts (1) 80,350 16,231 (26,888) 69,693 Valuation allowance for deferred tax assets (3) 23,562 — (981) 22,581 (1) The additions to the allowance for doubtful accounts represent the provision for doubtful accounts that is recorded based upon the Company's evaluation of the collectability of accounts receivable. Deductions/Adjustments are primarily related to actual write-offs of receivables and other adjustments. (2) The increase in the valuation allowance for deferred tax assets is primarily related to an increase in net operating loss carryforwards not expected to be realized prior to expiration. Refer to Note 16 - Income Taxes in the consolidated financial statements included in Part II, Item 8, of this Form 10-K for further details. (3) The decrease in the valuation allowance for deferred tax assets is primarily related to removal of valuation allowance on net loss carryforwards due to current period taxable income.

Basis of Presentation and Sum_2

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of presentation	The accompanying consolidated financial statements of the Company were prepared in accordance with U.S. GAAP and in accordance with the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”). The Company's indirect wholly-owned subsidiaries include, but are not limited to, ATI Holdings Acquisition, Inc. and ATI Holdings, LLC.
Liquidity and going concern	Liquidity and going concern In accordance with Accounting Standards Codification ("ASC") Topic 205-40, Going Concern , the Company has evaluated whether there are certain conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within twelve months after the date that these consolidated financial statements are issued. This evaluation includes considerations related to the covenants contained in the Company’s 2022 Credit Agreement as well as the Company’s liquidity position overall.
Principles of consolidation	Principles of consolidation The consolidated financial statements include the financial statements of the Company, its subsidiaries, entities for which the Company has a controlling financial interest, and variable interest entities ("VIEs") for which the Company is the primary beneficiary. All intercompany balances and transactions have been eliminated in consolidation, and net earnings are reduced by the portion of net earnings attributable to non-controlling interests.
Variable interest entities	Variable interest entities The Company consolidates all variable interest entities where the Company is the primary beneficiary. The Company identifies the primary beneficiary of a VIE as the enterprise that has both: (i) the power to direct the activities of the VIE that most significantly impact the entity's economic performance; and (ii) the obligation to absorb losses or the right to receive benefits of the VIE that could be significant to the entity. The Company may change the original assessment of a VIE upon subsequent events such as the modification of contractual agreements.
Use of estimates	Use of estimates The preparation of the consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates. The effect of any change in estimates will be recognized in the current period of the change.
Segment reporting	Segment reporting The Company reports segment information based on the management approach. The management approach designates the internal reporting used by management for making decisions and assessing performance as the source of the Company’s reportable segments. All of the Company’s operations are conducted within the United States. Our chief operating decision maker (“CODM”) is our Chief Executive Officer, who reviews financial information presented on a consolidated basis for purposes of making decisions, assessing financial performance and allocating resources. We operate our business as one operating segment and therefore we have one reportable segment.
Cash, cash equivalents and restricted cash	Cash, cash equivalents and restricted cash Cash and cash equivalents include all cash balances and highly liquid investments with original maturities of three months or less when issued. Restricted cash that was included within cash and cash equivalents as presented within our consolidated balance sheets as of December 31, 2022 and our consolidated statements of cash flows for the year ended December 31, 2022 was $0.8 million.
Accounts receivable	Accounts receivable The Company's accounts receivable are reported net of contractual adjustments and allowances for doubtful accounts. The majority of accounts receivable are due from commercial insurance companies, workers' compensation plans, auto personal injury claims and government health programs, such as Medicare or Medicaid. The Company reports accounts receivable at an amount equal to the consideration the Company expects to receive in exchange for providing healthcare services to its patients.
Allowance for doubtful accounts	Allowance for doubtful accounts The allowance for doubtful accounts is based on estimates of losses related to receivable balances. The risk of collection varies based upon the service, the payor class and the patient’s ability to pay the amounts not reimbursed by the payor. The Company estimates the allowance for doubtful accounts based upon several factors, including the age of the outstanding receivables, the historical experience of collections, the impact of economic conditions and, in some cases, evaluating specific customer accounts for the ability to pay. Management judgment is used to assess the collectability of accounts and the ability of the Company’s customers to pay. The provision for doubtful accounts is included in cost of services in the consolidated statements of operations. When it is determined that a customer account is uncollectible, that balance is written off against the existing allowance.
Concentrations of business risk	Concentrations of business riskThe Company provides physical therapy services to a large number of patients who participate in government healthcare programs, resulting in a customer concentration relating to Medicare and Medicaid’s service reimbursement programs. The Company believes that the concentration of credit risk with respect to other patient accounts receivable is limited due to the large number of patients that make up the Company’s patient base and the dispersion across many different insurance companies, preferred provider organizations and individuals.
Net patient and other revenue	Net patient revenue Net patient revenue consists of revenue for physical therapy services. Net patient revenue is recognized at an amount equal to the consideration the Company expects to receive from third-party payors, patients and others for services rendered when the performance obligations under the terms of the contract are satisfied. There is an implied contract between the Company and the patient upon each patient visit resulting in the Company’s patient service performance obligation. Generally, the performance obligation is satisfied at a point in time, as each service provided is distinct and future services rendered are not dependent on previously rendered services. The Company has separate contractual agreements with third-party payors (e.g., insurers, managed care programs, government programs, workers' compensation) that provide for payments to the Company at amounts different from its established rates. While these agreements are not considered contracts with the customer, they are used for determining the transaction price for services provided to the patients covered by the third-party payors. The payor contracts do not indicate performance obligations of the Company but indicate reimbursement rates for patients who are covered by those payors when the services are provided. To determine the transaction price associated with the implied contract, the Company includes the estimated effects of any variable consideration, such as contractual allowances and implicit price concessions. When the Company has contracts with negotiated prices for services provided (contracted payors), the Company considers the contractual rates when recording revenue and adjusts for any variable consideration to the transaction price to arrive at revenue. Variable consideration is estimated using a portfolio approach that incorporates whether or not the Company has historical differences from negotiated rates due to non-compliance with contract provisions. Historical results indicate that it is probable that negotiated prices less variable consideration will be realized; therefore, this amount is deemed the transaction price and recorded as revenue. The Company records an estimated provision for doubtful accounts based on historical collections for claims with similar characteristics, such as location of service and type of third-party payor, at the time of recognition. Any subsequent impairment of the related receivable is recorded as provision for doubtful accounts. For non-contracted payors, the Company determines the transaction price by applying established rates to the services provided and adjusting for contractual allowances provided to third-party payors and implicit price concessions. The Company estimates the contractual allowances and implicit price concessions using a portfolio approach based on historical collections for claims with similar characteristics, such as location of service and type of third-party payor, in relation to established rates, because the Company does not have a contract with the underlying payor. Any subsequent changes in estimate on the realization of the receivable is recorded as a revenue adjustment. Management believes that calculating at the portfolio level would not differ materially from considering each patient account separately. The Company continually reviews the revenue transaction price estimation process to consider updates to laws and regulations and changes in third-party payor contractual terms that result from contract renegotiations and renewals. Due to complexities involved in determining amounts ultimately due under reimbursement arrangements with third-party payors and government entities, which are often subject to interpretation, the Company may receive reimbursement for healthcare services that is different from the estimates, and such differences could be material. Other revenue Revenue from the ATI Worksite Solutions business is derived from on-site services provided to clients’ employees including injury prevention, rehabilitation, ergonomic assessments and performance optimization. Revenue is determined based on the number of hours and respective rate for services provided. Revenues from Management Service Agreements (“MSA”) are derived from contractual arrangements whereby the Company manages a non-controlled clinic or clinics for third-party owners. The Company does not have any ownership interest in these clinics. Typically, revenue is determined based on the number of visits conducted at the clinic and recognized when services are performed. Costs, primarily salaries for the Company’s employees, are recorded when incurred. Other revenue includes physical or occupational therapy services and athletic training provided on-site, such as at schools and industrial worksites. Contract terms and rates are agreed to in advance between the Company and the third-parties. Services are typically performed over the contract period, and revenue is recorded in accordance with the contract terms. If the services are paid in advance, revenue is deferred and recognized as the services are performed.
Property and equipment	Property and equipment Property and equipment acquired is recorded at cost less accumulated depreciation, except during an acquisition of a business, in which case the assets are initially recorded at fair value. Depreciation is calculated using the straight-line method and is provided in amounts sufficient to attribute the cost of depreciable assets to operations over the estimated useful lives. The approximate useful life of each class of property and equipment is as follows: Equipment 3 - 5 years Furniture & fixtures 5 - 7 years Automobiles 3 - 5 years Software 3 - 5 years Buildings 40 years Leasehold improvements Lesser of lease term or estimated useful lives of the assets (generally 5 - 15 years) Major repairs that extend the useful life of an asset are capitalized to the property and equipment account. Routine maintenance and repairs are charged to rent, clinic supplies, contract labor and other expenses and selling, general and administrative expenses. Gains or losses associated with property and equipment retired or sold are included in earnings. Computer software is included in property and equipment and consists of purchased software and internally developed software. The Company capitalizes application-stage development costs for significant internally developed software projects. Once the software is ready for its intended use, these costs are amortized on a straight-line basis over the software’s estimated useful life. Costs recognized in the preliminary project phase and the post-implementation phase, as well as maintenance and training costs, are expensed as incurred.
Impairment of long-lived assets	Impairment of long-lived assets The Company reviews the recoverability of long-lived assets whenever events or circumstances occur indicating that the carrying value of the asset may not be recoverable. If the undiscounted cash flows related to the long-lived asset or asset group are not sufficient to recover the remaining carrying value of such asset or asset group, an impairment charge is recognized for the excess carrying amount over the fair value of the asset or asset group. The Company noted triggering events during 2022 which resulted in the recording of impairment losses, which were not material. The Company did not note any triggering events during 2021 or 2020 that resulted in the recording of an impairment loss.
Goodwill and intangible assets	Goodwill and intangible assets Goodwill represents the excess of the purchase price over the fair value of assets acquired and liabilities assumed. The Company accounts for goodwill and indefinite-lived intangible assets under Accounting Standards Codification (“ASC”) Topic 350, Intangibles – Goodwill and Other , which requires the Company to test goodwill and other indefinite-lived assets for impairment annually or whenever events or circumstances indicate that impairment may exist. The Company noted triggering events during 2021 and 2022 which resulted in the recording of impairment losses. The Company did not note any triggering events during 2020 that resulted in the recording of an impairment loss. Refer to Note 5 - Goodwill, Trade Name and Other Intangible Assets for further details. Due to the current economic uncertainty resulting from the COVID-19 pandemic, rising interest rates, inflation and other macroeconomic factors, the Company will continue to review the carrying amounts of goodwill and indefinite-lived assets for potential triggering events. The cost of acquired businesses is allocated first to its identifiable assets, both tangible and intangible, based on estimated fair values. Costs allocated to finite-lived identifiable intangible assets are generally amortized on a straight-line basis over the remaining estimated useful lives of the assets. The excess of purchase price over the fair value of identifiable assets acquired, net of liabilities assumed, is recorded as goodwill. The approximate useful life of each class of intangible asset is as follows: ATI Physical Therapy trade name/trademark Indefinite Non-compete agreements 2 - 5 years Other intangible assets 15 years Goodwill and intangible assets with indefinite lives are not amortized but must be reviewed at least annually for impairment. If the impairment test indicates that the carrying value of the reporting unit exceeds its fair value, then a goodwill impairment loss should be recognized in the consolidated statements of operations in an amount equal to the excess carrying value over fair value. If the impairment test indicates that the carrying value of an intangible asset exceeds its fair value, then an impairment loss should be recognized in the consolidated statements of operations in an amount equal to the excess carrying value over fair value. Fair value is determined using valuation techniques based on estimates, judgments and assumptions the Company believes are appropriate in the circumstances. The Company completed the interim and annual impairment analyses of goodwill as of March 31, 2022, June 30, 2022, September 30, 2022, October 1, 2022 and December 31, 2022 by estimating its fair value using an average of a discounted cash flow analysis and comparable public company analysis. The key assumptions associated with determining the estimated fair value include projected revenue growth rates, EBITDA margins, the terminal growth rate, the discount rate and relevant market multiples. The Company completed the interim and annual impairment analyses of the indefinite-lived intangible asset as of March 31, 2022, June 30, 2022, September 30, 2022, October 1, 2022 and December 31, 2022 by estimating its fair value using the relief from royalty method. The key assumptions associated with determining the estimated fair value include projected revenue growth rates, the royalty rate, the discount rate and the terminal growth rate.
Deferred financing costs	Deferred financing costsOriginal debt issuance discounts and costs incurred related to debt financing are recorded as a reduction to debt and amortized ratably over the term of the related debt agreement, using the effective interest method. Deferred financing costs related to revolving credit facilities are recognized as assets and amortized ratably over the term of the related agreement using the effective interest method. Deferred financing costs are amortized to interest expense, net in the Company’s consolidated statements of operations.
Preferred stock	Preferred stock Preferred stock is classified as debt, equity or mezzanine equity based on its redemption features. Preferred stock with redemption features outside of the control of the issuer, such as contingent redemption features, is classified as mezzanine equity. Preferred stock with mandatory redemption features is classified as debt. Preferred stock with no redemption features, or redemption features over which the issuer has control, is classified as equity. The Company has preferred stock that is classified as mezzanine equity in the Company's consolidated balance sheets. Refer to Note 11 - Mezzanine and Stockholders' Equity for more information about the Company’s outstanding Series A Senior Preferred Stock. The Company had preferred stock that was classified as debt (redeemable preferred stock) in the Company’s consolidated balance sheets, prior to its redemption as part of the Business Combination. Refer to Note 12 - Wilco Holdco Redeemable Preferred Stock for more information about the Company’s previously outstanding preferred stock.
Treasury stock	Treasury stock Treasury stock amounts are accounted for under the cost method whereby the entire cost of the acquired stock is recorded as treasury stock. Gains and losses on the subsequent reissuance of shares are credited or charged to paid-in capital in excess of par value using the average-cost method.
Warrant liability	Warrant liability The Company accounts for its outstanding Public Warrants and Private Placement Warrants in accordance with the guidance contained in ASC 815-40, Derivatives and Hedging - Contracts on an Entity’s Own Equity , and determined that the IPO Warrants do not meet the criteria for equity treatment thereunder. As such, each IPO Warrant must be recorded as a liability and is subject to re-measurement at each balance sheet date. Changes in fair value are recognized in change in fair value of warrant liability in the Company’s consolidated statements of operations.
Contingent common shares liability	Contingent common shares liability The Company accounts for its potential Earnout Shares and Vesting Shares as a liability in accordance with the guidance in ASC 480, Distinguishing Liabilities from Equity , and ASC 815, Derivatives and Hedging, and is subject to re-measurement at each balance sheet date. Changes in fair value are recognized in the Company’s consolidated statements of operations.
Non-controlling interests in consolidated affiliates	Non-controlling interests in consolidated affiliates The consolidated financial statements include all assets, liabilities, revenues and expenses of less-than-100%-owned affiliates where the Company has a controlling financial investment. The Company has separately reflected net (loss) income attributable to the non-controlling interests in net (loss) income in the consolidated statements of operations.
Fair value of financial instruments	Fair value of financial instruments The Company determines fair value measurements used in its consolidated financial statements based upon the exit price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants exclusive of any transaction costs, as determined by either the principal market or the most advantageous market at the measurement date. Inputs used in the valuation techniques to derive fair values are classified based on a three-level hierarchy. The basis for fair value measurements for each level within the hierarchy is described below with Level 1 having the highest priority and Level 3 having the lowest. • Level 1: Observable inputs, which include unadjusted quoted prices in active markets for identical instruments. • Level 2: Observable inputs other than Level 1 inputs, such as quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the instruments. • Level 3: Unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions, such as valuations derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable. Refer to Note 15 - Fair Value Measurements for valuation techniques and inputs related to the Company's financial instruments and share-based liabilities.
Income taxes	Income taxes The Company accounts for income taxes in accordance with ASC Topic 740 (“ASC 740”), Income Taxes . Under ASC 740, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and the respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rate is recognized in operations in the period that includes the enactment date. ASC 740 provides guidance on how uncertain tax positions should be recognized, measured, presented and disclosed in the financial statements. ASC 740 requires the evaluation of tax positions taken or expected to be taken in the course of preparing the Company’s tax returns to determine whether the tax positions are more likely than not of being sustained by the applicable tax authority. A tax position that meets the more-likely-than-not recognition threshold is measured and recognized in the consolidated financial statements at the largest amount of benefit that is greater than 50% likely of being realized upon settlement. Tax positions deemed to not meet a more-likely-than-not threshold may not be recognized in the financial statements. The Company reviews these tax uncertainties in light of changing facts and circumstances, such as the progress of tax audits, and if any tax uncertainties were identified, the Company would recognize them accordingly. The liability relating to uncertain tax positions is classified as current in the consolidated balance sheets to the extent the company anticipates making a payment within one year. Interest and penalties associated with income taxes are classified in the income tax (benefit) expense line in the consolidated statements of operations.
Cost of services	Cost of services Cost of services consist of salaries specific to the Company’s clinic operations along with rent, clinic supplies expense, depreciation and advertising costs. In addition, cost of services includes the provision for doubtful accounts.
Selling, general and administrative expenses	Selling, general and administrative expenses Selling, general and administrative expenses consist primarily of wages and benefits for corporate personnel, corporate outside services, marketing costs, depreciation of corporate fixed assets, amortization of intangible assets and certain corporate level professional fees, including those related to legal, accounting and payroll.
Advertising costs	Advertising costsAdvertising costs are expensed as incurred or when services are rendered.
Share-based compensation	Share-based compensation The Company applies the guidance in ASC Topic 718, Compensation - Stock Compensation , in its accounting for share-based compensation. The Company recognizes compensation expense for all share-based compensation awarded to employees, net of forfeitures, using a fair value-based method. The grant-date fair value of each award is amortized to expense on a straight-line basis over the award’s vesting period. Compensation expense associated with share-based awards is included in salaries and related costs and selling, general and administrative expenses in the accompanying consolidated statements of operations, depending on whether the award recipient is a clinic-level or corporate employee, respectively. Share-based compensation expense is adjusted for forfeitures as incurred.
Loss per share	Loss per share The Company applies the guidance in ASC Topic 260, Earnings Per Share , in its computation of loss per share. Basic loss per share is computed by dividing net loss by the weighted average number of common shares outstanding during the period. Diluted loss per share is computed by dividing net loss by the weighted average number of common shares and dilutive common share equivalents outstanding. Refer to Note 19 - Loss per Share for more information.
Leases	Leases The Company applies the guidance in ASC Topic 842 (“ASC 842”), Leases, to classify individual leases of assets as either operating or finance leases at contract inception. All leased assets have been classified as operating lease arrangements, and the Company’s classes of leased assets include real estate and equipment. The Company adopted ASC 842 on January 1, 2020 using the alternative transition method. Operating lease balances are included in operating lease right-of-use (“ROU”) assets, current portion of operating lease liabilities and operating lease liabilities in the Company’s consolidated balance sheets. ROU assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent its obligation to make lease payments arising from the lease. ROU assets and lease liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term, adjusted for prepaid or accrued lease payments and lease incentives. The Company’s lease terms include the impact of options to extend or terminate the lease when it is reasonably certain that the options will be exercised or not exercised, as appropriate. When discount rates implicit in leases cannot be readily determined, the Company uses the applicable incremental borrowing rate at lease commencement to perform lease classification tests on lease components and to measure lease liabilities and ROU assets. The Company's incremental borrowing rate is the rate of interest that it would have to pay to borrow on a collateralized basis, over a similar term, an amount equal to the lease payments in a similar economic environment. Leases with an initial term of 12 months or less are not recorded on the balance sheet. The ROU asset is subject to testing for impairment if there is an indicator for impairment, as is the case for owned assets. The Company noted triggering events during 2021 and 2022 which resulted in the recording of impairment losses, which were not material. The Company did not note any triggering events during 2020 that resulted in the recording of an impairment loss. The amortization of operating lease ROU assets and the accretion of operating lease liabilities are reported together as fixed lease expense. The fixed lease expense is recognized on a straight-line basis over the life of the lease. If the ROU asset has been impaired, lease expense is no longer recognized on a straight-line basis. The lease liability continues to amortize using the effective interest method, while the ROU asset is subsequently amortized on a straight-line basis. Some of the Company’s operating leases include variable lease payments, which include periodic adjustments of the Company's payments for the use of the asset based on changes in factors such as consumer price indices, fair market value, tax rates imposed by taxing authorities or lessor cost of insurance. To the extent they are not included in operating lease liabilities and operating lease ROU assets, these variable lease payments are recognized as incurred. Additionally, the Company makes payments for property taxes, insurance, common area maintenance or other services and accounts for these costs as variable lease payments.
Recently adopted accounting guidance	Recently adopted accounting guidance In February 2016, the Financial Accounting Standards Board (“FASB”) established ASC Topic 842, Leases , by issuing Accounting Standards Update ("ASU") No. 2016-02, which requires lessees to recognize leases on-balance sheet and disclose key information about leasing arrangements. ASC 842 was subsequently amended by ASU No. 2018-01, Land Easement Practical Expedient for Transition to Topic 842 ; ASU No. 2018-10, Codification Improvements to Topic 842, Leases ; ASU No. 2018-11, Targeted Improvements ; ASU No. 2019-01, Codification Improvements ; and ASU No. 2019-10, Leases (Topic 842) . ASC 842 establishes a right-of-use model that requires a lessee to recognize a ROU asset and lease liability on the balance sheet for all leases with a term longer than 12 months. Leases will be classified as finance or operating, with classification affecting the pattern and classification of expense recognition in the statement of operations. ASC 842 was effective for the Company on January 1, 2021, with early adoption permitted. The Company elected to early adopt this standard on January 1, 2020 using the alternative transition method provided by ASC 842. Under the alternative transition method, the effects of initially applying the new guidance were recognized as a cumulative-effect adjustment to retained earnings at the date of initial application, which is January 1, 2020. As part of transitioning to ASC 842, the Company elected to apply the package of transition practical expedients, which allowed the Company to not reassess under ASC 842 prior conclusions about lease identification, lease classification and initial direct costs. As a result of adopting ASC 842 and election of the transition practical expedients, the Company recognized ROU assets and lease liabilities for those leases classified as operating leases under ASC 840 that continued to be classified as operating leases under ASC 842 at the date of initial application. Leases classified as capital under ASC 840 are classified as finance under ASC 842. As of the date of transition to ASC 842, the Company did not have any capital leases under ASC 840. The Company elected the practical expedient within ASC 842 to not separate lease and non-lease components within lease transactions for all classes of assets. Additionally, the Company elected the short-term lease exception for all classes of assets. In applying the alternative modified retrospective transition method, the Company measured lease liabilities at the present value of the sum of remaining minimum lease payments. The Company’s operating lease liabilities were measured using the Company’s incremental borrowing rates as of January 1, 2020 (the date of initial application). Additionally, the Company’s operating lease ROU assets were measured as the initial measurement of applicable lease liabilities adjusted for any unamortized initial direct costs, prepaid/accrued rent, unamortized lease incentives and any liabilities on account of exit or disposal cost obligations. Adoption of ASC 842 at January 1, 2020, and application of the alternative modified retrospective transition method resulted in the recognition of: (1) operating lease ROU assets of $263.2 million; (2) operating lease liabilities of $306.4 million; (3) the cumulative effect adjustment to increase the opening balance of the accumulated deficit by $0.4 million; Adoption of this standard did not have a material impact on the Company’s consolidated statements of operations and consolidated statements of cash flows. Refer to Note 17 - Leases for more information about the Company’s lease related obligations. In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting , which provides optional guidance for a limited period of time to ease the potential burden in accounting for (or recognizing the effects of) reference rate reform on financial reporting. This standard was subsequently amended by ASU No. 2021-01, Reference Rate Reform (Topic 848): Scope , and by ASU 2022-06, Reference Rate Reform (Topic 848): Deferral of the Sunset Date of Topic 848 . This standard is optional and may be applied by entities after March 12, 2020, but no later than December 31, 2024. As of December 31, 2022, the Company has a derivative instrument for which the interest rate is indexed to the London InterBank Offered Rate (“LIBOR”). During the period ended March 31, 2022, the Company modified the reference rate index on its hedged items, which are future variable-rate cash payments, from LIBOR to the Secured Overnight Financing Rate ("SOFR"). The Company elected to apply the hedge accounting expedients related to probability and the assessments of effectiveness for future cash flows to assume that the index upon which future hedged transactions will be based matches the index on the corresponding derivative, which is LIBOR. The guidance allows for different expedient elections to be made at different points in time. As of December 31, 2022, the Company continues to apply the hedge accounting expedients and does not anticipate that this guidance will have a material impact on its consolidated financial statements, however, the Company will continue to assess the potential impact on its future hedging relationships and expedient elections, as applicable. In October 2021, the FASB issued ASU 2021-08, Business Combinations (Topic 805): Accounting for Contract Assets and Liabilities from Contracts with Customers , which provides guidance to improve the accounting for acquired revenue contracts with customers in a business combination by addressing diversity in practice. This ASU is effective for the Company on January 1, 2023, with early adoption permitted, and shall be applied on a prospective basis to business combinations that occur on or after the adoption date. The Company adopted this new accounting standard effective January 1, 2023. The Company does not expect the adoption of this ASU to have a material impact on the Company's consolidated financial statements. In November 2021, the FASB issued ASU 2021-10, Government Assistance (Topic 832): Disclosures by Business Entities about Government Assistance , which provides guidance to increase the transparency of government assistance transactions with business entities that are accounted for by applying a grant or contribution accounting model. This ASU is effective for the Company's annual financial statements to be issued for the year ended December 31, 2022, with early adoption permitted. The Company adopted this new accounting standard in this Annual Report on Form 10-K for the year ended December 31, 2022. The adoption of this standard did not have a material impact on the Company's consolidated financial statements.

Basis of Presentation and Sum_3

Basis of Presentation and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Property and Equipment	The approximate useful life of each class of property and equipment is as follows: Equipment 3 - 5 years Furniture & fixtures 5 - 7 years Automobiles 3 - 5 years Software 3 - 5 years Buildings 40 years Leasehold improvements Lesser of lease term or estimated useful lives of the assets (generally 5 - 15 years) Property and equipment consisted of the following at December 31, 2022 and December 31, 2021 (in thousands): December 31, 2022 December 31, 2021 Equipment $ 38,102 $ 36,278 Furniture and fixtures 17,215 17,141 Leasehold improvements 191,182 183,542 Automobiles 19 19 Computer equipment and software 102,651 95,362 Construction-in-progress 3,727 3,793 352,896 336,135 Accumulated depreciation and amortization (229,206) (196,405) Property and equipment, net (1) $ 123,690 $ 139,730 (1) Excludes $1.1 million reclassified as held for sale as of December 31, 2022. Refer to Note 3 - Business Combinations and Divestitures for additional information. The following table presents the amount of depreciation and amortization expense related to property and equipment recorded in rent, clinic supplies, contract labor and other and selling, general and administrative expenses in the Company’s consolidated statements of operations for the periods indicated below (in thousands): Year Ended December 31, 2022 December 31, 2021 December 31, 2020 Rent, clinic supplies, contract labor and other $ 27,429 $ 26,664 $ 25,409 Selling, general and administrative expenses 12,417 10,873 14,101 Total depreciation expense $ 39,846 $ 37,537 $ 39,510
Schedule of Carrying Amounts of Indefinite-Lived Intangible Assets	The approximate useful life of each class of intangible asset is as follows: ATI Physical Therapy trade name/trademark Indefinite Non-compete agreements 2 - 5 years Other intangible assets 15 years The table below summarizes the Company’s carrying amount of trade name and other intangible assets at December 31, 2022 and December 31, 2021 (in thousands): December 31, 2022 December 31, 2021 Gross intangible assets: ATI trade name (1) $ 245,000 $ 409,360 Non-compete agreements 2,395 2,405 Other intangible assets 640 640 Accumulated amortization: Accumulated amortization – non-compete agreements (1,126) (425) Accumulated amortization – other intangible assets (327) (284) Total trade name and other intangible assets, net $ 246,582 $ 411,696 (1) Not subject to amortization. The Company recorded $164.4 million of impairment charges related to the trade name indefinite-lived intangible asset during the year ended December 31, 2022.
Schedule of Carrying Amounts of Finite-Lived Intangible Assets	The approximate useful life of each class of intangible asset is as follows: ATI Physical Therapy trade name/trademark Indefinite Non-compete agreements 2 - 5 years Other intangible assets 15 years The table below summarizes the Company’s carrying amount of trade name and other intangible assets at December 31, 2022 and December 31, 2021 (in thousands): December 31, 2022 December 31, 2021 Gross intangible assets: ATI trade name (1) $ 245,000 $ 409,360 Non-compete agreements 2,395 2,405 Other intangible assets 640 640 Accumulated amortization: Accumulated amortization – non-compete agreements (1,126) (425) Accumulated amortization – other intangible assets (327) (284) Total trade name and other intangible assets, net $ 246,582 $ 411,696 (1) Not subject to amortization. The Company recorded $164.4 million of impairment charges related to the trade name indefinite-lived intangible asset during the year ended December 31, 2022.

Business Combinations and Div_2

Business Combinations and Divestitures (Tables)	12 Months Ended
Business Combinations and Divestitures (Tables)	Dec. 31, 2022
Business Combination and Asset Acquisition [Abstract]
Summary of Shares Issued and Flow of Funds Related to Business Combination	Immediately following the Business Combination, there were 207.3 million shares issued and 196.6 million outstanding shares of common stock of ATI Physical Therapy, Inc., consisting of the following (in thousands): Class A Common Shares FAII Class A common stock prior to Business Combination 34,500 FAII Class F common stock prior to Business Combination (1) 8,625 Less: FAII Class A common stock redemptions (8,988) FAII common shares (Class A and Class F) 34,137 Add: Shares issued to Wilco Holdco stockholders (2, 3) 130,300 Add: Shares issued through PIPE investment 30,000 Add: Shares issued to Wilco Holdco Series A Preferred stockholders 12,845 Total shares issued as of the Closing Date of the Business Combination (4) 207,282 Less: Vesting Shares (1) (8,625) Less: Restricted shares (3) (2,014) Total shares outstanding as of the Closing Date of the Business Combination (4) 196,643 (1) Per the Merger Agreement, as of the closing of the Business Combination, all Class F shares converted into the equivalent number of Class A common shares and became subject to certain vesting and forfeiture provisions ("Vesting Shares") as detailed in Note 14 - Contingent Common Shares Liability . (2) Includes 1.2 million unrestricted shares upon distribution to holders of vested ICUs under the Wilco Acquisition, LP 2016 Equity Incentive Plan. Refer to Note 10 - Share-Based Compensation for further details. (3) Includes 2.0 million restricted shares upon distribution to holders of unvested ICUs under the Wilco Acquisition, LP 2016 Equity Incentive Plan. Refer to Note 10 - Share-Based Compensation for further details. (4 ) Excludes 15.0 million Earnout Shares, 6.9 million Public Warrants and 3.0 million Private Placement Warrants to purchase Class A common stock. Refer to Note 13 - IPO Warrant Liability and Note 14 - Contingent Common Shares Liability for further details. The following table reflects the components of cash movement related to the Business Combination, PIPE investment and debt repayments (in thousands): Cash in trust with FAII as of the Closing Date of the Business Combination $ 345,036 Cash used for redemptions of FAII Class A common stock (89,877) FAII transaction costs paid at closing (25,821) Cash inflow from Business Combination 229,338 Wilco Holdco, Inc. transaction costs offset against proceeds (19,233) Net proceeds from FAII in Business Combination 210,105 Cash proceeds from PIPE investment 300,000 Repayment of second lien subordinated loan (231,335) Partial repayment of 2016 first lien term loan (216,700) Cash payment to Wilco Holdco Series A Preferred stockholders (59,000) Wilco Holdco, Inc. transaction costs expensed during 2021 (5,543) Net decrease in cash related to Business Combination, PIPE investment and debt repayments $ (2,473)
Schedule of Disposal Groups, Including Discontinued Operations	Major classes of assets and liabilities classified as held for sale as of December 31, 2022 were as follows (in thousands): December 31, 2022 Accounts receivable, net $ 486 Prepaid expenses 23 Property and equipment, net 1,113 Operating lease right-of-use assets 1,929 Goodwill, net 3,192 Other non-current assets 12 Total assets held for sale $ 6,755 Accounts payable $ 22 Accrued expenses and other liabilities 201 Current portion of operating lease liabilities 685 Operating lease liabilities 1,706 Total liabilities held for sale $ 2,614

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	12 Months Ended
Revenue from Contracts with Customers (Tables)	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregation of Net Operating Revenue By Major Service Line and Associated Payor Class	The following table disaggregates net revenue by major service line for the periods indicated below (in thousands): Year Ended December 31, 2022 December 31, 2021 December 31, 2020 Net patient revenue $ 575,940 $ 561,080 $ 529,585 ATI Worksite Solutions (1) 35,515 34,583 30,864 Management Service Agreements (1) 12,857 15,246 15,837 Other revenue (1) 11,359 16,962 15,967 $ 635,671 $ 627,871 $ 592,253 (1) ATI Worksite Solutions, Management Service Agreements and Other revenue are included within other revenue on the face of the consolidated statements of operations. The following table disaggregates net patient revenue for each associated payor class as a percentage of total net patient revenue for the periods indicated below: Year Ended December 31, 2022 December 31, 2021 December 31, 2020 Commercial 57.6 % 56.3 % 53.1 % Government 24.2 % 23.7 % 22.2 % Workers’ compensation 12.4 % 14.3 % 17.6 % Other (1) 5.8 % 5.7 % 7.1 % 100.0 % 100.0 % 100.0 %

Goodwill, Trade Name and Othe_2

Goodwill, Trade Name and Other Intangible Assets (Tables)	12 Months Ended
Goodwill, Trade Name and Other Intangible Assets (Tables)	Dec. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Changes in The Carrying Amount of Goodwill	Changes in the carrying amount of goodwill consisted of the following (in thousands): Total Goodwill Goodwill at December 31, 2021 (1) $ 608,811 Impairment charges (318,925) Acquisitions (2) (236) Held for sale reclassifications (3) (3,192) Goodwill at December 31, 2022 $ 286,458 (1) Net of accumulated impairment losses of $726.8 million. (2) Represents final valuation adjustments related to 2021 acquisitions. Refer to Note 3 - Business Combinations and Divestitures for additional information. (3) Goodwill reclassified to assets held for sale is related to clinics held for sale as of December 31, 2022. Refer to Note 3 - Business Combinations and Divestitures for additional information.
Schedule of Carrying Amounts of Indefinite-Lived Intangible Assets	The approximate useful life of each class of intangible asset is as follows: ATI Physical Therapy trade name/trademark Indefinite Non-compete agreements 2 - 5 years Other intangible assets 15 years The table below summarizes the Company’s carrying amount of trade name and other intangible assets at December 31, 2022 and December 31, 2021 (in thousands): December 31, 2022 December 31, 2021 Gross intangible assets: ATI trade name (1) $ 245,000 $ 409,360 Non-compete agreements 2,395 2,405 Other intangible assets 640 640 Accumulated amortization: Accumulated amortization – non-compete agreements (1,126) (425) Accumulated amortization – other intangible assets (327) (284) Total trade name and other intangible assets, net $ 246,582 $ 411,696 (1) Not subject to amortization. The Company recorded $164.4 million of impairment charges related to the trade name indefinite-lived intangible asset during the year ended December 31, 2022.
Schedule of Carrying Amounts of Finite-Lived Intangible Assets	The approximate useful life of each class of intangible asset is as follows: ATI Physical Therapy trade name/trademark Indefinite Non-compete agreements 2 - 5 years Other intangible assets 15 years The table below summarizes the Company’s carrying amount of trade name and other intangible assets at December 31, 2022 and December 31, 2021 (in thousands): December 31, 2022 December 31, 2021 Gross intangible assets: ATI trade name (1) $ 245,000 $ 409,360 Non-compete agreements 2,395 2,405 Other intangible assets 640 640 Accumulated amortization: Accumulated amortization – non-compete agreements (1,126) (425) Accumulated amortization – other intangible assets (327) (284) Total trade name and other intangible assets, net $ 246,582 $ 411,696 (1) Not subject to amortization. The Company recorded $164.4 million of impairment charges related to the trade name indefinite-lived intangible asset during the year ended December 31, 2022.

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
Property and Equipment (Tables)	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment and Depreciation Expense	The approximate useful life of each class of property and equipment is as follows: Equipment 3 - 5 years Furniture & fixtures 5 - 7 years Automobiles 3 - 5 years Software 3 - 5 years Buildings 40 years Leasehold improvements Lesser of lease term or estimated useful lives of the assets (generally 5 - 15 years) Property and equipment consisted of the following at December 31, 2022 and December 31, 2021 (in thousands): December 31, 2022 December 31, 2021 Equipment $ 38,102 $ 36,278 Furniture and fixtures 17,215 17,141 Leasehold improvements 191,182 183,542 Automobiles 19 19 Computer equipment and software 102,651 95,362 Construction-in-progress 3,727 3,793 352,896 336,135 Accumulated depreciation and amortization (229,206) (196,405) Property and equipment, net (1) $ 123,690 $ 139,730 (1) Excludes $1.1 million reclassified as held for sale as of December 31, 2022. Refer to Note 3 - Business Combinations and Divestitures for additional information. The following table presents the amount of depreciation and amortization expense related to property and equipment recorded in rent, clinic supplies, contract labor and other and selling, general and administrative expenses in the Company’s consolidated statements of operations for the periods indicated below (in thousands): Year Ended December 31, 2022 December 31, 2021 December 31, 2020 Rent, clinic supplies, contract labor and other $ 27,429 $ 26,664 $ 25,409 Selling, general and administrative expenses 12,417 10,873 14,101 Total depreciation expense $ 39,846 $ 37,537 $ 39,510

Accrued Expenses and Other Li_2

Accrued Expenses and Other Liabilities (Tables)	12 Months Ended
Accrued Expenses and Other Liabilities (Tables)	Dec. 31, 2022
Payables and Accruals [Abstract]
Summary of Accrued Expenses and Other Liabilities	Accrued expenses and other liabilities consisted of the following at December 31, 2022 and December 31, 2021 (in thousands): December 31, 2022 December 31, 2021 Salaries and related costs $ 28,949 $ 27,257 Credit balances due to patients and payors 6,117 4,240 Accrued professional fees 5,551 5,998 Accrued contract labor 4,483 2,057 Accrued occupancy costs 2,410 1,895 CARES Act funds (1) — 18,179 Other payables and accrued expenses 6,162 4,958 Total $ 53,672 $ 64,584 (1) Includes current portion of MAAPP funds received and deferred employer Social Security tax payments.

Borrowings (Tables)

Borrowings (Tables)	12 Months Ended
Borrowings (Tables)	Dec. 31, 2022
Debt Disclosure [Abstract]
Summary of Long-Term Debt	Long-term debt consisted of the following at December 31, 2022 and December 31, 2021 (in thousands): December 31, 2022 December 31, 2021 Senior Secured Term Loan (1, 2) (due February 24, 2028) $ 503,481 $ — Revolving Loans (3) (due February 24, 2027) 48,200 — 2016 first lien term loan (4) — 555,048 Less: unamortized debt issuance costs (11,137) (1,935) Less: unamortized original issue discount (8,944) (1,147) Total debt, net 531,600 551,966 Less: current portion of long-term debt — (8,167) Long-term debt, net $ 531,600 $ 543,799 (1) Interest rate of 12.1% at December 31, 2022, with interest payable in designated installments at a variable interest rate. The effective interest rate for the Senior Secured Term Loan was 13.1% at December 31, 2022. (2) During the third and fourth quarters of 2022, the Company elected to pay a portion of its interest in-kind on its Senior Secured Term Loan by capitalizing and adding such interest to the principal amount of the debt. As of December 31, 2022, the Company recognized paid in-kind interest in the amount of $3.5 million. (3) Interest rate of 8.3% at December 31, 2022, with interest payable in designated installments at a variable interest rate. (4) Loan balance was repaid in its entirety on February 24, 2022. The effective interest rate for the 2016 first lien term loan was 4.9% at December 31, 2021.
Schedule of Aggregate Maturities of Long-Term Debt	Aggregate maturities of long-term debt at December 31, 2022 are as follows (in thousands): 2023 $ — 2024 — 2025 — 2026 — 2027 48,200 Thereafter 503,481 Total future maturities 551,681 Unamortized original issue discount and debt issuance costs (20,081) Total debt, net $ 531,600

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
Employee Benefit Plans (Tables)	Dec. 31, 2022
Retirement Benefits [Abstract]
Schedule of Defined Contribution Plan Disclosures	The following table presents the Company’s matching contributions to the plan recorded in cost of services and selling, general and administrative expenses in the consolidated statements of operations for the periods indicated below (in thousands): Year Ended December 31, 2022 December 31, 2021 December 31, 2020 Salaries and related costs $ 4,374 $ 4,102 $ 4,206 Selling, general and administrative expenses 559 532 520 Total $ 4,933 $ 4,634 $ 4,726

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
Share-Based Compensation (Tables)	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
Schedule of Share-Based Payment Arrangement, Option, Activity	The following table summarizes the activity of stock options for the year ended December 31, 2022 (aggregate intrinsic value in thousands): Number of Options Weighted-Average Exercise Price Weighted-Average Contractual Term (in years) Aggregate Intrinsic Value Outstanding, January 1, 2022 774,796 $ 3.41 9.9 $ 9 Granted 6,369,881 1.69 N/A N/A Exercised — — N/A — Forfeited/Cancelled (1,831,938) 1.98 N/A N/A Outstanding, December 31, 2022 5,312,739 $ 1.84 9.1 $ — Exercisable, December 31, 2022 202,337 $ 3.40 6.9 $ — Expected to vest, December 31, 2022 5,110,402 $ 1.78 9.2 $ —
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	The following table summarizes the weighted-average grant-date fair value and assumptions used to develop the fair value estimates for the options granted in 2022 and 2021. No stock options were granted under the 2021 Plan during the year ended December 31, 2020: 2022 2021 Weighted-average grant-date fair value of options $0.98 $1.69 Risk-free interest rate 1.74% 1.45% Term (years) 6.2 6.0 Volatility 61.19% 51.67% Expected dividend —% —%
Schedule of Share-Based Payment Arrangement, Restricted Stock Unit, Activity	The following table summarizes the activity of unvested RSUs and the respective weighted-average grant date fair value per RSU for the year ended December 31, 2022: 2022 RSUs Weighted-Average Grant Date Fair Value Outstanding and unvested, beginning of year 404,235 $ 3.41 Granted (1) 5,428,281 2.08 Vested (489,461) 3.58 Forfeited (1,143,246) 2.23 Outstanding and unvested, end of year 4,199,809 $ 1.99 (1) The vesting start date for certain RSUs granted in 2022 is the Closing Date
Nonvested Restricted Stock Shares Activity	The following table summarizes the activity of unvested RSAs and respective weighted-average grant date fair value per RSA for the year ended December 31, 2022: 2022 RSAs Weighted-Average Grant Date Fair Value Outstanding and unvested, beginning of year 447,731 $ 3.42 Granted — — Vested (144,795) 3.42 Forfeited (128,227) 3.42 Outstanding and unvested, end of year 174,709 $ 3.42

Mezzanine and Stockholders' E_2

Mezzanine and Stockholders' Equity (Tables)	12 Months Ended
Mezzanine and Stockholders' Equity (Tables)	Dec. 31, 2022
Equity [Abstract]
Schedule of Temporary Equity	The following table reflects the components of proceeds related to the Series A Senior Preferred Stock (in thousands): Gross proceeds allocated to Series A Senior Preferred Stock $ 144,667 Less: original issue discount (1,447) Less: issuance costs (2,880) Net proceeds received from issuance of Series A Senior Preferred Stock $ 140,340 The following table presents the change in the aggregate stated value and stated value per share of the Series A Senior Preferred Stock since the Refinancing Date (in thousands, except per share data): Series A Senior Preferred Stock Aggregate stated value as of February 24, 2022 $ 165,000 Accumulated paid in-kind dividends as of December 31, 2022 17,876 Aggregate stated value as of December 31, 2022 $ 182,876 Preferred shares issued and outstanding as of December 31, 2022 165 Stated value per share as of December 31, 2022 $ 1,108.34
Schedule of Components Of Proceeds Related to Warrants	The following table reflects the components of proceeds related to the 2022 Warrants (in thousands): Series I Warrants Series II Warrants Total Gross proceeds allocated to 2022 Warrants $ 5,101 $ 15,232 $ 20,333 Less: original issue discount (51) (152) (203) Less: issuance costs (102) (303) (405) Net proceeds received from issuance of 2022 Warrants $ 4,948 $ 14,777 $ 19,725
Schedule of Shares of Class A Common Stock Reserved for Potential Future Issuance	As of December 31, 2022, shares of Class A common stock reserved for potential future issuance, on an as-if converted basis, were as follows (in thousands): December 31, 2022 Shares available for grant under the 2021 Plan 10,862 2021 Plan share-based awards outstanding 9,687 Earnout Shares reserved 15,000 2022 Warrants outstanding 11,498 IPO Warrants outstanding 9,867 Vesting Shares reserved (1) 8,625 Restricted shares (1,2) 402 Total shares of common stock reserved 65,941 (1) Represents shares of Class A common stock legally issued, but not outstanding, as of December 31, 2022. (2) Represents a portion of the 2.0 million restricted shares distributed following the Business Combination to holders of unvested Incentive Common Units under the Wilco Acquisition, LP 2016 Equity Incentive Plan.

IPO Warrant Liability (Tables)

IPO Warrant Liability (Tables)	12 Months Ended
IPO Warrant Liability (Tables)	Dec. 31, 2022
Other Liabilities Disclosure [Abstract]
Summary of Warrant Liability	The following table presents the change in the fair value of Private Placement Warrants that is recognized in change in fair value of warrant liability in the consolidated statements of operations for the periods indicated below (in thousands): Year Ended December 31, 2022 December 31, 2021 Fair value, beginning of period (1) $ 1,305 $ 8,099 Changes in fair value (1) (1,276) (6,794) Fair value, end of period $ 29 $ 1,305 (1) The year ended December 31, 2021 represents changes in fair value from the Closing Date of the Business Combination, which is when the liabilities were established. The following table presents the changes in the fair value of the Public Warrants that is recognized in change in fair value of warrant liability in the consolidated statements of operations for the periods indicated below (in thousands): Year Ended December 31, 2022 December 31, 2021 Fair value, beginning of period (1) $ 3,036 $ 18,837 Changes in fair value (1) (2,967) (15,801) Fair value, end of period $ 69 $ 3,036 (1) The year ended December 31, 2021 represents changes in fair value from the Closing Date of the Business Combination, which is when the liabilities were established.

Contingent Common Shares Liab_2

Contingent Common Shares Liability (Tables)	12 Months Ended
Contingent Common Shares Liability (Tables)	Dec. 31, 2022
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Change in Fair Value of Earn Out Shares	The following table presents the changes in the fair value of the Earnout Shares that is recognized in change in fair value of contingent common shares liability in the consolidated statements of operations for the periods indicated below (in thousands): Year Ended December 31, 2022 December 31, 2021 Fair value, beginning of period (1) $ 28,800 $ 140,000 Changes in fair value (1) (27,000) (111,200) Fair value, end of period $ 1,800 $ 28,800 (1) The year ended December 31, 2021 represents changes in fair value from the Closing Date of the Business Combination, which is when the liabilities were established. The following table presents the changes in the fair value of the Vesting Shares that is recognized in change in fair value of contingent common shares liability in the consolidated statements of operations for the periods indicated below (in thousands): Year Ended December 31, 2022 December 31, 2021 Fair value, beginning of period (1) $ 16,560 $ 80,500 Changes in fair value (1) (15,525) (63,940) Fair value, end of period $ 1,035 $ 16,560 (1) The year ended December 31, 2021 represents changes in fair value from the Closing Date of the Business Combination, which is when the liabilities were established.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
Fair Value Measurements (Tables)	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Schedule of Key Fair Value Measurement Inputs	The key inputs into the Monte-Carlo option pricing model were as follows as of December 31, 2022 and December 31, 2021 for the respective Level 3 instruments : Earnout Shares Vesting Shares December 31, 2022 December 31, 2021 December 31, 2022 December 31, 2021 Risk-free interest rate 3.88% 1.50% 3.88% 1.50% Volatility 74.60% 44.86% 74.60% 44.86% Dividend yield —% —% —% —% Expected term (years) 8.5 9.5 8.5 9.5 Share price $0.31 $3.39 $0.31 $3.39
Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss)	The following table presents the activity of cash flow hedges included in accumulated other comprehensive income (loss) for the years ended December 31, 2022 and 2021, respectively (in thousands): Cash Flow Hedges Balance as of December 31, 2021 $ 28 Unrealized gain recognized in other comprehensive income before reclassifications 8,310 Reclassification to interest expense, net (3,439) Balance as of December 31, 2022 $ 4,899 Balance as of December 31, 2020 $ (1,907) Unrealized gain recognized in other comprehensive income before reclassifications 490 Reclassification to interest expense, net 1,445 Balance as of December 31, 2021 $ 28
Schedule of Fair Value of Derivative Assets and Liabilities	The following table presents the fair value of derivative assets and liabilities within the consolidated balance sheets as of December 31, 2022 and December 31, 2021 (in thousands): December 31, 2022 December 31, 2021 Assets Liabilities Assets Liabilities Derivatives designated as cash flow hedging instruments: Other current assets $ 5,028 $ — $ — $ — Other non-current assets — — 277 — Accrued expenses and other liabilities — — — 288 Other non-current liabilities — 73 — —

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
Income Taxes (Tables)	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax (Benefit) Expense	The Company's (loss) income before taxes consists of only domestic operations. The details of the Company's income tax (benefit) expense for the years ended December 31, 2022, 2021 and 2020 are as follows (in thousands): 2022 2021 2020 Current: Federal $ 6 $ — $ — State 37 128 251 Total current 43 128 251 Deferred: Federal (37,634) (60,002) 3,514 State (10,939) (11,086) (1,700) Total deferred (48,573) (71,088) 1,814 Total income tax (benefit) expense $ (48,530) $ (70,960) $ 2,065
Schedule of Effective Income Tax Rate Reconciliation	The differences between the federal tax rate and the Company's effective tax rate for the years ended December 31, 2022, 2021 and 2020 are as follows (in thousands): 2022 2021 2020 Federal income tax benefit at statutory rate $ (113,731) 21.0 % $ (179,128) 21.0 % $ (694) 21.0 % State income tax (benefit) expense, net of federal tax benefit (16,827) 3.1 % (25,814) 3.0 % 1,248 (37.8) % Change in state tax rate 5 — % 34 — % (2,551) 77.1 % Prior period adjustments and other 167 — % 1,515 (0.2) % (105) 3.2 % Valuation allowance 31,595 (5.8) % 35,731 (4.2) % (981) 29.7 % Interest expense on redeemable preferred stock — — % 2,118 (0.2) % 3,997 (120.9) % Changes in fair value of warrant liability and contingent common shares liability (9,821) 1.8 % (41,524) 4.9 % — — % Goodwill impairment charges 59,893 (11.1) % 132,447 (15.5) % — — % Other permanent differences, net 189 — % 3,661 (0.5) % 1,151 (34.8) % Total income tax (benefit) expense $ (48,530) 9.0 % $ (70,960) 8.3 % $ 2,065 (62.5) %
Schedule of Deferred Tax Assets and Liabilities	Deferred income taxes have been provided on temporary differences, which consist of the following at December 31, 2022 and 2021 (in thousands): 2022 2021 Deferred income tax assets: Accrued liabilities $ 7,112 $ 10,420 Provision for bad debt 11,828 12,530 Operating lease liabilities 64,288 74,115 Acquisition and transaction costs 3,186 3,770 Net operating losses 104,419 82,304 Interest expense 43,323 33,163 Other deferred tax assets 6,335 4,798 Total gross deferred income tax assets 240,491 221,100 Valuation allowance (89,907) (58,312) Total gross deferred income tax assets, net of valuation allowance 150,584 162,788 Deferred income tax liabilities: Goodwill 26,251 26,563 Trade name/trademark 66,445 114,451 Operating lease right-of-use assets 54,360 63,252 Depreciation 20,039 22,089 Other deferred tax liabilities 2,375 3,892 Total gross deferred income tax liabilities 169,470 230,247 Net deferred income tax liabilities $ 18,886 $ 67,459
Schedule of Unrecognized Tax Benefits Roll Forward	Of the gross unrecognized tax benefits, none were recognized as liabilities in the consolidated balance sheets in any year due to tax attribute carryforwards available to offset a potential tax liability. 2022 2021 2020 Balance at beginning of period $ — $ 3,027 $ 2,341 Increases for positions taken during the year — — 686 Decreases for positions taken in prior years — (3,027) — Balance at end of period $ — $ — $ 3,027

Leases (Tables)

Leases (Tables)	12 Months Ended
Leases (Tables)	Dec. 31, 2022
Leases [Abstract]
Schedule of Lease Cost, Supplemental Cash Flow, and Other Information Related to Leases	Lease costs incurred by lease type were as follows for the periods indicated below (in thousands): Year Ended December 31, 2022 December 31, 2021 December 31, 2020 Lease cost Operating lease cost (1) $ 69,533 $ 65,555 $ 67,279 Variable lease cost (2) 20,951 20,045 18,689 Total lease cost (3) $ 90,484 $ 85,600 $ 85,968 (1) Includes ROU asset impairment charges of $2.6 million and $1.2 million for the years ended December 31, 2022 and 2021, respectively. (2) Includes short term lease costs, which are immaterial . (3) Sublease income was immaterial . Other supplemental quantitative disclosures were as follows for the periods indicated below (in thousands): Year Ended December 31, 2022 December 31, 2021 December 31, 2020 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 72,440 $ 65,678 $ 61,993 Cash payments related to lease terminations $ — $ 4,570 $ — Right-of-use assets obtained in exchange for new operating lease liabilities $ 9,688 $ 28,759 $ 14,067 Average lease terms and discount rates as of December 31, 2022 and December 31, 2021 were as follows: December 31, 2022 December 31, 2021 Weighted-average remaining lease term: Operating leases 5.9 years 6.4 years Weighted-average discount rate: Operating leases 6.9% 6.5%
Schedule of Estimated Undiscounted Future Lease Payments	Estimated undiscounted future lease payments under non-cancellable operating leases, along with a reconciliation of the undiscounted cash flows to operating lease liabilities, respectively, at December 31, 2022 were as follows (in thousands): Year Amount (1) 2023 $ 64,066 2024 61,885 2025 52,459 2026 46,069 2027 35,108 Thereafter 68,006 Total undiscounted future cash flows 327,593 Less: Imputed Interest (61,493) Present value of future cash flows $ 266,100 Presentation on Balance Sheet Current $ 47,676 Non-current $ 218,424 (1) Excludes $0.7 million of current portion of operating lease liabilities and $1.7 million of operating lease liabilities, respectively, reclassified as held for sale as of December 31, 2022. Refer to Note 3 - Business Combinations and Divestitures for additional information.

Loss per Share (Tables)

Loss per Share (Tables)	12 Months Ended
Loss per Share (Tables)	Dec. 31, 2022
Earnings Per Share [Abstract]
Schedule of Calculation of Both Basic and Diluted Loss Per Share	The calculation of both basic and diluted loss per share for the periods indicated below was as follows (in thousands, except per share data): Year Ended December 31, 2022 December 31, 2021 December 31, 2020 Basic and diluted loss per share: Net loss $ (493,047) $ (782,028) $ (298) Less: Net (loss) income attributable to non-controlling interests (668) (3,700) 5,073 Less: Series A Senior Preferred cumulative dividend 17,876 — — Loss available to common stockholders $ (510,255) $ (778,328) $ (5,371) Weighted average shares outstanding (1,2) 203,150 165,805 128,286 Basic and diluted loss per share $ (2.51) $ (4.69) $ (0.04) (1) The weighted-average number of shares outstanding in periods presented prior to the closing of the Business Combination has been retrospectively adjusted based on the exchange ratio established through the transaction. (2) Included within weighted average shares outstanding following the 2022 Debt Refinancing are common shares issuable upon the exercise of the Series II Warrants, as the Series II Warrants are exercisable at any time for nominal consideration. As such, the shares are considered to be outstanding for the purpose of calculating basic and diluted loss per share.
Schedule of Antidilutive Securities Excluded From Computation of Diluted Shares Outstanding	For the periods presented, the following securities were not required to be included in the computation of diluted shares outstanding, as their impact would have been anti-dilutive. Figures presented are based on the number of underlying Class A common shares following the Business Combination (in thousands): Year Ended December 31, 2022 December 31, 2021 December 31, 2020 Series I Warrants 5,226 — — IPO Warrants 9,867 9,867 — Restricted shares (1) 402 1,323 — Stock options 5,313 775 — RSUs 4,200 404 — RSAs 175 448 — Total 25,183 12,817 — (1) Represents a portion of the 2.0 million restricted shares distributed following the Business Combination to holders of unvested Incentive Common Units under the Wilco Acquisition, LP 2016 Equity Incentive Plan. Refer to Note 10 - Share-Based Compensation for further details.

Overview of the Company (Detail

Overview of the Company (Details) $ in Thousands	3 Months Ended	12 Months Ended
Overview of the Company (Details) $ in Thousands	Jun. 30, 2020 USD ($)	Dec. 31, 2022 USD ($) clinic state	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of stores \| clinic		923
Number of stores under management service agreements \| clinic		20
Number of states in which entity operates \| state		25
Unusual or Infrequent Item, or Both [Line Items]
Accrued expenses and other liabilities		$ 53,672	$ 64,584
CARES Act, Provider Relief Fund
Unusual or Infrequent Item, or Both [Line Items]
General distributions received				$ 91,500
CARES Act, MAAPP Funds
Unusual or Infrequent Item, or Both [Line Items]
General distributions received	$ 26,700
Proceeds from sale of Home Health service line		12,300	12,600
Transferred to government assistance			1,800
Accrued expenses and other liabilities		0	12,300
Government Assistance, CARES Act, Deferral Of Employer Portion Of Social Security Taxes
Unusual or Infrequent Item, or Both [Line Items]
Accrued expenses and other liabilities		$ 0	$ 5,900

Basis of Presentation and Sum_4

Basis of Presentation and Summary of Significant Accounting Policies - Narrative (Details)			12 Months Ended
	Mar. 15, 2023 USD ($)	Feb. 24, 2022 USD ($)	Dec. 31, 2022 USD ($) segment	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Jan. 01, 2020 USD ($)
Finite-Lived Intangible Assets [Line Items]
Cash and cash equivalents			$ 83,139,000	$ 48,616,000
Net cash (used in) provided by operating activities			(65,508,000)	(42,100,000)	$ 138,604,000
Operating loss			(539,734,000)	(980,038,000)	(913,000)
Net loss			493,047,000	782,028,000	298,000
Accumulated deficit			1,339,511,000	847,132,000
Total assets			1,078,985,000	1,562,694,000
Total liabilities			$ 890,198,000	1,051,187,000
Number of operating segments \| segment			1
Number of reportable segments \| segment			1
Restricted cash included within cash and cash equivalents			$ 800,000
Amortization of debt issuance costs			1,700,000	2,300,000	3,000,000
Debt issuance discounts			1,200,000	1,000,000	$ 1,000,000
Operating lease right-of-use assets			226,092,000	256,646,000
Present value of future cash flows			266,100,000
Accounting Standards Update 2016-02
Finite-Lived Intangible Assets [Line Items]
Accumulated deficit						$ (400,000)
Operating lease right-of-use assets						263,200,000
Present value of future cash flows						$ 306,400,000
Variable Interest Entity, Primary Beneficiary \| RSFH Investment
Finite-Lived Intangible Assets [Line Items]
Total assets			10,100,000	13,300,000
Total liabilities			5,000,000	$ 6,500,000
2022 Credit Agreement
Finite-Lived Intangible Assets [Line Items]
Minimum liquidity amount		$ 30,000,000
2022 Credit Agreement \| Revolving Credit Facility \| Line of Credit
Finite-Lived Intangible Assets [Line Items]
Line of credit facility borrowing capacity			0
Total available liquidity			$ 72,900,000
Maximum borrowing capacity		$ 50,000,000
2022 Credit Agreement \| Beginning in the second quarter of 2024
Finite-Lived Intangible Assets [Line Items]
Maximum debt to EBITDA ratio allowed		7
2022 Credit Agreement \| In third quarter of 2024
Finite-Lived Intangible Assets [Line Items]
Maximum debt to EBITDA ratio allowed		6.75
2022 Credit Agreement \| First quarter of 2025
Finite-Lived Intangible Assets [Line Items]
Maximum debt to EBITDA ratio allowed		6.25
Second Lien PIK Convertible Notes \| Convertible Debt \| Subsequent Event
Finite-Lived Intangible Assets [Line Items]
Maximum borrowing capacity	$ 25,000,000
Senior Secured Term Loan (due February 24, 2028) \| Secured Debt \| Subsequent Event
Finite-Lived Intangible Assets [Line Items]
Conversion of convertible notes to common stock	$ 100,000,000
Debt instrument, conversion ratio	0.25

Basis of Presentation and Sum_5

Basis of Presentation and Summary of Significant Accounting Policies - Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2022
Equipment \| Minimum
Property, Plant and Equipment [Line Items]
,Useful life	3 years
Equipment \| Maximum
Property, Plant and Equipment [Line Items]
,Useful life	5 years
Furniture and fixtures \| Minimum
Property, Plant and Equipment [Line Items]
,Useful life	5 years
Furniture and fixtures \| Maximum
Property, Plant and Equipment [Line Items]
,Useful life	7 years
Automobiles \| Minimum
Property, Plant and Equipment [Line Items]
,Useful life	3 years
Automobiles \| Maximum
Property, Plant and Equipment [Line Items]
,Useful life	5 years
Computer equipment and software \| Minimum
Property, Plant and Equipment [Line Items]
,Useful life	3 years
Computer equipment and software \| Maximum
Property, Plant and Equipment [Line Items]
,Useful life	5 years
Buildings
Property, Plant and Equipment [Line Items]
,Useful life	40 years
Leasehold improvements \| Minimum
Property, Plant and Equipment [Line Items]
,Useful life	5 years
Leasehold improvements \| Maximum
Property, Plant and Equipment [Line Items]
,Useful life	15 years

Basis of Presentation and Sum_6

Basis of Presentation and Summary of Significant Accounting Policies - Intangible Assets (Details)	12 Months Ended
	Dec. 31, 2022
Non-compete agreements \| Minimum
Finite-Lived Intangible Assets [Line Items]
Useful life	2 years
Non-compete agreements \| Maximum
Finite-Lived Intangible Assets [Line Items]
Useful life	5 years
Other intangible assets
Finite-Lived Intangible Assets [Line Items]
Useful life	15 years

Basis of Presentation and Sum_7

Basis of Presentation and Summary of Significant Accounting Policies - Advertising Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Salaries and related costs
Property, Plant and Equipment [Line Items]
Advertising expense	$ 3.4	$ 3.2	$ 2.3
Selling, general and administrative expenses
Property, Plant and Equipment [Line Items]
Advertising expense	$ 4.7	$ 5.1	$ 4.8

Business Combinations and Div_3

Business Combinations and Divestitures - Narrative (Details) $ / shares in Units, $ in Thousands			12 Months Ended
	Oct. 01, 2021 USD ($)	Jun. 16, 2021 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) clinic center $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares
Schedule Of Reverse Recapitalization [Line Items]
Shares issued to Wilco Holdco stockholders (in shares)		130,300,000
Common stock, par value (in dollars per share) \| $ / shares		$ 0.01	$ 0.0001	$ 0.0001
Exchange ratio		136.7
Common stock, shares Issued (in shares)		207,282,000	207,400,000	207,500,000
Common stock, shares outstanding (in shares)		196,643,000	197,400,000	198,400,000
Transaction cost \| $			$ 5,543
Transaction cost off-set against additional paid-in capital \| $			19,200
Goodwill, net \| $			$ 608,811	$ 286,458
Three Acquisitions 2021
Schedule Of Reverse Recapitalization [Line Items]
Number of businesses acquired \| center			3
Number of clinics \| clinic			7
Cash consideration \| $			$ 4,500
Contingent consideration liability \| $			1,400
Goodwill, net \| $			$ 5,500
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Home Health service line
Schedule Of Reverse Recapitalization [Line Items]
Sale price \| $	$ 7,300
Gain on disposition of business \| $	$ 5,800
Public Warrant
Schedule Of Reverse Recapitalization [Line Items]
Number of shares called by each warrant		6,900,000		6,900,000
Private Placement Warrant
Schedule Of Reverse Recapitalization [Line Items]
Number of shares called by each warrant		3,000,000		3,000,000
Warrants transferred and surrender in conjunction with business combination (in shares)		3,000,000
Earnout Shares
Schedule Of Reverse Recapitalization [Line Items]
Contingent common share liability (in shares, up to)		15,000,000
Contingent common share liability term		10 years
Vesting Shares
Schedule Of Reverse Recapitalization [Line Items]
Contingent common share liability (in shares, up to)		8,600,000
Contingent common share liability term		10 years
2016 Plan
Schedule Of Reverse Recapitalization [Line Items]
Unrestricted shares ( in shares)		1,200,000
Wilco Holdco, Inc.
Schedule Of Reverse Recapitalization [Line Items]
Common stock, par value (in dollars per share) \| $ / shares		$ 0.01
Class A Common Stock
Schedule Of Reverse Recapitalization [Line Items]
Shares issued to Wilco Holdco stockholders (in shares)		130,300,000
Shares issued to Wilco Holdco stockholders, value per share (in dollars per share) \| $ / shares		$ 0.0001
Common stock, par value (in dollars per share) \| $ / shares				$ 0.0001
Unrestricted shares ( in shares)		128,300,000
Common stock, shares Issued (in shares)				207,500,000
Common stock, shares outstanding (in shares)				198,400,000
Number of shares issued as consideration		30,000,000
Price per share (in dollars per share) \| $ / shares		$ 10
Aggregate purchase price \| $		$ 300,000
Equity consideration transferred in exchange for redemption of preferred stock \| $		$ 59,000
Equity consideration transferred in exchange for redemption of preferred stock (in shares)		12,800,000
Class A Common Stock \| Fortress
Schedule Of Reverse Recapitalization [Line Items]
Number of shares issued as consideration		7,500,000
Price per share (in dollars per share) \| $ / shares		$ 10
Aggregate purchase price \| $		$ 75,000
Class A Common Stock \| 2016 Plan
Schedule Of Reverse Recapitalization [Line Items]
Restricted shares (in shares)		2,000,000

Business Combinations and Div_4

Business Combinations and Divestitures - Summary of Shares Issued and Outstanding (Details) - shares	Jun. 16, 2021	Dec. 31, 2022	Dec. 31, 2021	Jun. 15, 2021
Schedule Of Reverse Recapitalization [Line Items]
Common stock, shares outstanding (in shares)	196,643,000	198,400,000	197,400,000
FAII common shares (in shares)	34,137,000
Add: Shares issued to Wilco Holdco stockholders (in shares)	130,300,000
Add: Shares issued through PIPE investment (in shares)	30,000,000
Shares issued to Wilco Holdco Series A Preferred stockholders (in shares)	12,845,000
Total shares issued as of the Closing Date of the Business Combination (in shares)	207,282,000	207,500,000	207,400,000
Less: Vesting Shares (in shares)	(8,625,000)
Less: Restricted shares (in shares)	(2,014,000)
Common stock, shares outstanding (in shares)	196,643,000	198,400,000	197,400,000
Public Warrant
Schedule Of Reverse Recapitalization [Line Items]
Number of shares called by each warrant	6,900,000	6,900,000
Private Placement Warrant
Schedule Of Reverse Recapitalization [Line Items]
Number of shares called by each warrant	3,000,000	3,000,000
2016 Plan
Schedule Of Reverse Recapitalization [Line Items]
Unrestricted shares (in shares)	1,200,000
Earnout Shares
Schedule Of Reverse Recapitalization [Line Items]
Contingent consideration liability (in shares)	15,000,000
Class A Common Stock
Schedule Of Reverse Recapitalization [Line Items]
Common stock, shares outstanding (in shares)		198,400,000
Add: Shares issued to Wilco Holdco stockholders (in shares)	130,300,000
Total shares issued as of the Closing Date of the Business Combination (in shares)		207,500,000
Common stock, shares outstanding (in shares)		198,400,000
Unrestricted shares (in shares)	128,300,000
Class A Common Stock \| 2016 Plan
Schedule Of Reverse Recapitalization [Line Items]
Restricted shares (in shares)	2,000,000
Class A Common Stock \| FAII
Schedule Of Reverse Recapitalization [Line Items]
Common stock, shares outstanding (in shares)				34,500,000
Less: FAII Class A common stock redemptions (in shares)	(8,988,000)
Common stock, shares outstanding (in shares)				34,500,000
Class F Common Stock \| FAII
Schedule Of Reverse Recapitalization [Line Items]
Common stock, shares outstanding (in shares)				8,625,000
Common stock, shares outstanding (in shares)				8,625,000

Business Combinations and Div_5

Business Combinations and Divestitures - Flow of Funds (Details) - USD ($) $ in Thousands		12 Months Ended
	Jun. 16, 2021	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule Of Reverse Recapitalization [Line Items]
Cash in trust with FAII as of the Closing Date of the Business Combination	$ 345,036
Cash used for redemptions of FAII Class A common stock	(89,877)
FAII transaction costs paid at closing	(25,821)
Cash inflow from Business Combination	229,338	$ 0	$ 229,338	$ 0
Wilco Holdco, Inc. transaction costs offset against proceeds	(19,233)
Net proceeds from FAII in Business Combination	210,105
Cash proceeds from PIPE investment	300,000	0	300,000	0
Cash payment to Wilco Holdco Series A Preferred stockholders	(59,000)	$ 0	(59,000)	$ 0
Wilco Holdco, Inc. transaction costs expensed during 2021			(5,543)
Net decrease in cash related to Business Combination, PIPE investment and debt repayments			$ (2,473)
Second Lien Subordinated Loan
Schedule Of Reverse Recapitalization [Line Items]
Repayments of debt	(231,335)
2016 first lien term loan
Schedule Of Reverse Recapitalization [Line Items]
Repayments of debt	$ (216,700)

Business Combinations and Div_6

Business Combinations and Divestitures - Assets and Liabilities Classified as Held For Sale (Details) - Disposal Group, Held-for-sale, Not Discontinued Operations - 2022 Clinics Held for Sale $ in Thousands	Dec. 31, 2022 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts receivable, net	$ 486
Prepaid expenses	23
Property and equipment, net	1,113
Operating lease right-of-use assets	1,929
Goodwill, net	3,192
Other non-current assets	12
Total assets held for sale	6,755
Accounts payable	22
Accrued expenses and other liabilities	201
Current portion of operating lease liabilities	685
Operating lease liabilities	1,706
Total liabilities held for sale	$ 2,614

Revenue from Contracts with C_3

Revenue from Contracts with Customers (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Net revenue	$ 635,671	$ 627,871	$ 592,253
Net patient revenue
Disaggregation of Revenue [Line Items]
Net revenue	$ 575,940	$ 561,080	$ 529,585
Net operating revenue (as percent)	100%	100%	100%
Net patient revenue \| Commercial
Disaggregation of Revenue [Line Items]
Net operating revenue (as percent)	57.60%	56.30%	53.10%
Net patient revenue \| Government
Disaggregation of Revenue [Line Items]
Net operating revenue (as percent)	24.20%	23.70%	22.20%
Net patient revenue \| Workers’ compensation
Disaggregation of Revenue [Line Items]
Net operating revenue (as percent)	12.40%	14.30%	17.60%
Net patient revenue \| Other
Disaggregation of Revenue [Line Items]
Net operating revenue (as percent)	5.80%	5.70%	7.10%
ATI Worksite Solutions
Disaggregation of Revenue [Line Items]
Net revenue	$ 35,515	$ 34,583	$ 30,864
Management Service Agreements
Disaggregation of Revenue [Line Items]
Net revenue	12,857	15,246	15,837
Other revenue
Disaggregation of Revenue [Line Items]
Net revenue	$ 11,359	$ 16,962	$ 15,967

Goodwill, Trade Name and Othe_3

Goodwill, Trade Name and Other Intangible Assets - Narrative (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2022 USD ($) unit	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Indefinite-lived Intangible Assets [Line Items]
Number of reporting units \| unit		1
Goodwill impairment loss		$ 318,925	$ 726,800
Impairment, Intangible Asset, Indefinite-Lived (Excluding Goodwill), Statement of Income or Comprehensive Income [Extensible Enumeration]			Goodwill, intangible and other asset impairment charges
Goodwill, intangible and other asset impairment charges		486,262	$ 962,303	$ 0
Error Accumulated In Previous Quarters
Indefinite-lived Intangible Assets [Line Items]
Goodwill, intangible and other asset impairment charges	$ (8,800)
Year Ended December 31, 2021 \| Error Accumulated In Previous Quarters
Indefinite-lived Intangible Assets [Line Items]
Goodwill, intangible and other asset impairment charges	$ (1,800)
ATI trade name
Indefinite-lived Intangible Assets [Line Items]
Impairment of indefinite lived intangible assets		$ 164,400	$ 234,300

Goodwill, Trade Name and Othe_4

Goodwill, Trade Name and Other Intangible Assets - Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Goodwill [Roll Forward]
Goodwill, Beginning Balance	$ 608,811
Impairment charges	(318,925)	$ (726,800)
Acquisitions	(236)
Held for sale reclassifications	(3,192)
Goodwill, Ending Balance	$ 286,458	608,811
Accumulated goodwill impairment loss		$ 726,800

Goodwill, Trade Name and Othe_5

Goodwill, Trade Name and Other Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Trade name and other intangible assets, net	$ 246,582	$ 411,696
ATI trade name
Indefinite-lived Intangible Assets [Line Items]
Gross intangible assets	245,000	409,360
Impairment of indefinite lived intangible assets	164,400	234,300
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross intangible assets:	2,395	2,405
Accumulated amortization:	(1,126)	(425)
Other intangible assets
Finite-Lived Intangible Assets [Line Items]
Gross intangible assets:	640	640
Accumulated amortization:	$ (327)	$ (284)

Property and Equipment - Carryi

Property and Equipment - Carrying Amount (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 352,896	$ 336,135
Accumulated depreciation and amortization	(229,206)	(196,405)
Property and equipment, net	123,690	139,730
Disposal Group, Held-for-sale, Not Discontinued Operations \| 2022 Clinics Held for Sale
Property, Plant and Equipment [Line Items]
Disposal group, including discontinued operation, property, plant and equipment	1,113
Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	38,102	36,278
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	17,215	17,141
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	191,182	183,542
Automobiles
Property, Plant and Equipment [Line Items]
Property and equipment, gross	19	19
Computer equipment and software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	102,651	95,362
Construction-in-progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	3,727	3,793
Software and Software Development Costs
Property, Plant and Equipment [Line Items]
Property and equipment, net	$ 64,300	$ 58,700

Property and Equipment - Deprec

Property and Equipment - Depreciation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total depreciation expense	$ 39,846	$ 37,537	$ 39,510
Rent, clinic supplies, contract labor and other
Property, Plant and Equipment [Line Items]
Total depreciation expense	27,429	26,664	25,409
Selling, general and administrative expenses
Property, Plant and Equipment [Line Items]
Total depreciation expense	$ 12,417	$ 10,873	$ 14,101

Property and Equipment - Narrat

Property and Equipment - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property and equipment, net	$ 123,690	$ 139,730
Total depreciation expense	39,846	37,537	$ 39,510
Software and Software Development Costs
Property, Plant and Equipment [Line Items]
Property and equipment, net	64,300	58,700
Total depreciation expense	$ 8,200	$ 6,800	$ 9,800

Accrued Expenses and Other Li_3

Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Payables and Accruals [Abstract]
Salaries and related costs	$ 28,949	$ 27,257
Credit balances due to patients and payors	6,117	4,240
Accrued professional fees	5,551	5,998
Accrued contract labor	4,483	2,057
Accrued occupancy costs	2,410	1,895
CARES Act funds	0	18,179
Other payables and accrued expenses	6,162	4,958
Accrued expenses and other liabilities	$ 53,672	$ 64,584

Borrowings - Long-Term Debt (De

Borrowings - Long-Term Debt (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Total future maturities	$ 551,681
Less: unamortized debt issuance costs	(11,137)	$ (1,935)
Less: unamortized original issue discount	(8,944)	(1,147)
Total debt, net	531,600	551,966
Less: current portion of long-term debt	0	(8,167)
Long-term debt, net	531,600	543,799
Paid in-kind interest amount	$ 3,481	0	$ 6,335
Senior Secured Term Loan (due February 24, 2028)
Debt Instrument [Line Items]
State interest rate (in percent)	12.10%
Effective interest rate (in percent)	13.10%
Senior Secured Term Loan (due February 24, 2028) \| Secured Debt
Debt Instrument [Line Items]
Total future maturities	$ 503,481	$ 0
Paid in-kind interest amount	3,500
2016 first lien term loan
Debt Instrument [Line Items]
Effective interest rate (in percent)		4.90%
2016 first lien term loan \| Secured Debt
Debt Instrument [Line Items]
Total future maturities	0	$ 555,048
2022 Credit Agreement \| Line of Credit \| Revolving Credit Facility
Debt Instrument [Line Items]
Total future maturities	48,200	$ 0
Less: unamortized debt issuance costs	$ (600)
State interest rate (in percent)	8.30%

Borrowings - Narrative (Details

Borrowings - Narrative (Details)				12 Months Ended
Borrowings - Narrative (Details)	Dec. 31, 2022 USD ($)	Feb. 24, 2022 USD ($)	Jun. 16, 2021 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Debt Instrument [Line Items]
Principal payments on long-term debt				$ 555,048,000	$ 456,202,000	$ 8,167,000
Loss on extinguishment of debt				2,809,000	5,534,000	0
Warrants purchase common stock aggregate stated value		$ 165,000,000
Balance of unamortized issuance costs	$ 11,137,000			11,137,000	1,935,000
Proceeds from revolving line of credit				48,200,000	0	$ 68,750,000
2016 first lien term loan
Debt Instrument [Line Items]
Principal payments on long-term debt		555,000,000	$ 216,700,000
Loss on extinguishment of debt		2,800,000	1,700,000
Second Lien Subordinated Loan
Debt Instrument [Line Items]
Principal payments on long-term debt			231,300,000
Loss on extinguishment of debt			$ 3,800,000
2022 Credit Agreement
Debt Instrument [Line Items]
Debt amount		550,000,000
Debt issuance costs, gross		12,500,000
Original issuance discount		10,000,000
Minimum liquidity amount		30,000,000
Prepayment upon insurance proceeds in excess of		$ 15,000,000
2022 Credit Agreement \| Beginning in the second quarter of 2024
Debt Instrument [Line Items]
Maximum debt to EBITDA ratio allowed		7
2022 Credit Agreement \| In third quarter of 2024
Debt Instrument [Line Items]
Maximum debt to EBITDA ratio allowed		6.75
2022 Credit Agreement \| First quarter of 2025
Debt Instrument [Line Items]
Maximum debt to EBITDA ratio allowed		6.25
2022 Credit Agreement \| Secured Debt
Debt Instrument [Line Items]
Debt amount		$ 500,000,000
Interest in-kind interest to pay		2%
Premium rate		0.50%
2022 Credit Agreement \| Secured Debt \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Debt Instrument [Line Items]
Floor rate (as a percent)	1%
Basis spread on variable rate (as a percent)	7.25%
2022 Credit Agreement \| Line of Credit
Debt Instrument [Line Items]
Line of credit facility, commitment fee percentage		0.50%
2022 Credit Agreement \| Line of Credit \| Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 50,000,000
Debt issuance costs, gross		500,000
Balance of unamortized issuance costs	$ 600,000			600,000
Borrowings outstanding	$ 48,200,000			48,200,000
Proceeds from revolving line of credit				48,200,000
2022 Credit Agreement \| Line of Credit \| Revolving Credit Facility \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	4.10%
2022 Credit Agreement \| Line of Credit \| Letter of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity		10,000,000
Letters of credit outstanding	$ 1,800,000			$ 1,800,000
First lien credit agreement \| Line of Credit \| Revolving Credit Facility
Debt Instrument [Line Items]
Debt issuance costs, gross		$ 200,000
Balance of unamortized issuance costs					300,000
First lien credit agreement \| Line of Credit \| Letter of Credit
Debt Instrument [Line Items]
Letters of credit outstanding					$ 1,200,000

Borrowings - Maturities (Detail

Borrowings - Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt Disclosure [Abstract]
2023	$ 0
2024	0
2025	0
2026	0
2027	48,200
Thereafter	503,481
Total future maturities	551,681
Unamortized original issue discount and debt issuance costs	(20,081)
Total debt, net	$ 531,600	$ 551,966

Employee Benefit Plans - Narrat

Employee Benefit Plans - Narratives (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Retirement Benefits [Abstract]
Maximum employee contribution, percent	100%
Defined contribution plan, employer matching contribution (in percent)	50%
Defined contribution plan, employer matching contribution, percent of employees' gross pay (in percent)	6%
Contributions to the plan	$ 4,933	$ 4,634	$ 4,726

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - USD ($) $ in Thousands	12 Months Ended
Employee Benefit Plans (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Contribution Plan Disclosure [Line Items]
Contributions to the plan	$ 4,933	$ 4,634	$ 4,726
Salaries and related costs
Defined Contribution Plan Disclosure [Line Items]
Contributions to the plan	4,374	4,102	4,206
Selling, general and administrative expenses
Defined Contribution Plan Disclosure [Line Items]
Contributions to the plan	$ 559	$ 532	$ 520

Share-Based Compensation - Narr

Share-Based Compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance (in shares)	65,941,000
Service-Base Vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance (in shares)	10,862,000
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, expiration period	10 years
Stock options \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Stock options \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	4 years
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining unvested shares (in shares)			0
RSUs \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	1 year
RSUs \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
RSAs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Common stock, capital shares reserved for future issuance (in shares)	402,000
2016 Plan \| Service-Base Vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Stock-based compensation expense	$ 0.8	$ 2.7	$ 1.9
Vested (in shares)	100,000
Awards granted in period (in shares)	0
Remaining unvested shares (in shares)	100,000
Unrecognized compensation expense	$ 0.6
Period of recognition	1 year 4 months 24 days
2016 Plan \| Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 0.3	$ 2.5
Vested (in shares)	200,000
Awards granted in period (in shares)	0
Remaining unvested shares (in shares)	100,000
Unrecognized compensation expense	$ 0.5
Period of recognition	1 year 6 months
Forfeited (in shares)	(100,000)
2016 Plan \| Performance Shares \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
2016 Plan \| Performance Shares \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	8 years
2021 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance ( in shares)	21,300,000
Common stock, capital shares reserved for future issuance (in shares)	10,900,000
Weighted-average grant-date fair value of options ( in dollar per share)	$ 0.98	$ 1.69
Share-based payment arrangement, nonvested award, option, cost not yet recognized, amount	$ 4.1
2021 Plan \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 1.3	$ 0.1	0
Period of recognition	2 years 10 months 24 days
2021 Plan \| RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 4.4	$ 0.1	$ 0
Vested (in shares)	489,461
Awards granted in period (in shares)	5,428,281	400,000	0
Remaining unvested shares (in shares)	4,199,809	404,235
Period of recognition	1 year 10 months 24 days
Forfeited (in shares)	(1,143,246)
Granted (in usd per share)	$ 2.08	$ 3.41
Fair value of vested	$ 1.8	$ 0
Non-vested awards, cost not yet recognized	5.6
2021 Plan \| RSAs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 0.5	$ 0.4	$ 0
Vested (in shares)	144,795
Awards granted in period (in shares)	0	600,000	0
Remaining unvested shares (in shares)	174,709	447,731	0
Period of recognition	1 year 6 months
Forfeited (in shares)	(128,227)
Granted (in usd per share)	$ 0	$ 3.42
Fair value of vested	$ 0.5	$ 0.4
Non-vested awards, cost not yet recognized	$ 0.6

Share-Based Compensation - Sche

Share-Based Compensation - Schedule of Share-based Payment Arrangement, Option, Activity (Details) - 2021 Plan - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Number of Options
Outstanding, beginning balance (in shares)	774,796
Granted (in shares)	6,369,881		0
Exercised (in shares)	0
Forfeited/Cancelled (in shares)	(1,831,938)
Outstanding, ending balance (in shares)	5,312,739	774,796
Expected to vest (in shares)	5,110,402
Exercisable (in shares)	202,337
Weighted-Average Exercise Price
Outstanding, beginning balance (in dollars per share)	$ 3.41
Granted (in dollars per share)	1.69
Exercised (in dollars per share)	0
Forfeited/Cancelled (in dollars per share)	1.98
Outstanding, ending balance (in dollars per share)	1.84	$ 3.41
Expected to vest, weighted-average exercise price (in shares)	1.78
Exercisable, weighted-average exercise price (in dollars per share)	$ 3.40
Weighted-Average Contractual Term (in years)
Outstanding	9 years 1 month 6 days	9 years 10 months 24 days
Expected to vest, weighted-average remaining contractual term	9 years 2 months 12 days
Exercisable, weighted-average remaining contractual term	6 years 10 months 24 days
Aggregate Intrinsic Value
Outstanding	$ 0	$ 9
Exercised	0
Expected to vest, aggregate intrinsic value	0
Exercisable, aggregate intrinsic value	$ 0

Share-Based Compensation - Valu

Share-Based Compensation - Valuation Assumption (Details) - 2021 Plan - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant-date fair value of options ( in dollar per share)	$ 0.98	$ 1.69
Granted (in shares)	6,369,881		0
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	1.74%	1.45%
Term (years)	6 years 2 months 12 days	6 years
Volatility	61.19%	51.67%
Expected dividend	0%	0%

Share-Based Compensation - Acti

Share-Based Compensation - Activity Of Unvested RSUs And The Respective Weighted-Average Fair Value (Details) - RSUs - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
RSUs
Outstanding at beginning of period (in shares)		0
Outstanding at ending of period (in shares)			0
2021 Plan
RSUs
Outstanding at beginning of period (in shares)	404,235
Granted (in shares)	5,428,281	400,000	0
Vested (in shares)	(489,461)
Forfeited (in shares)	(1,143,246)
Outstanding at ending of period (in shares)	4,199,809	404,235
Weighted-Average Grant Date Fair Value
Outstanding at beginning of period, (in usd per share)	$ 3.41
Granted (in usd per share)	2.08	$ 3.41
Vested (in usd per share)	3.58
Forfeited, (in usd per share)	2.23
Outstanding at ending of period, (in usd per share)	$ 1.99	$ 3.41

Share-Based Compensation - Ac_2

Share-Based Compensation - Activity Of Unvested RSAs And The Respective Weighted-Average Fair Value (Details) - RSAs - 2021 Plan - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
RSAs
Outstanding at beginning of period (in shares)	447,731	0
Granted (in shares)	0	600,000	0
Vested (in shares)	(144,795)
Forfeited (in shares)	(128,227)
Outstanding at ending of period (in shares)	174,709	447,731	0
Weighted-Average Grant Date Fair Value
Outstanding at beginning of period, (in usd per share)	$ 3.42
Granted (in usd per share)	0	$ 3.42
Vested (in usd per share)	3.42
Forfeited (in usd per share)	3.42
Outstanding at ending of period, (in usd per share)	$ 3.42	$ 3.42

Mezzanine and Stockholders' E_3

Mezzanine and Stockholders' Equity - Narrative (Details)				10 Months Ended	12 Months Ended
Mezzanine and Stockholders' Equity - Narrative (Details)	Dec. 31, 2022 USD ($) vote $ / shares shares	Feb. 24, 2022 USD ($) segment $ / shares shares	Jun. 16, 2021 $ / shares shares	Dec. 31, 2022 USD ($) vote $ / shares shares	Dec. 31, 2022 USD ($) vote $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($)	Jun. 15, 2021 shares
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)	200,000			200,000	200,000	0
Exercise price of warrant (in dollars per share) \| $ / shares	$ 11.50			$ 11.50	$ 11.50
Preferred stock, par value (dollars per share) \| $ / shares	0.0001			0.0001	0.0001	$ 0.0001
Preferred stock, stated value (dollars per share) \| $ / shares	$ 1,108.34			$ 1,108.34	$ 1,108.34
Warrants purchase common stock aggregate stated value \| $		$ 165,000,000
Preferred stock, shares authorized (in shares)	1,000,000			1,000,000	1,000,000	1,000,000
Preferred stock, shares outstanding (in shares)	200,000			200,000	200,000	0
Proceeds from issuance of Series A Senior Preferred Stock \| $					$ 144,667,000	$ 0	$ 0
Proceeds from issuance of warrants \| $		$ 20,333,000			$ 20,333,000	$ 0	$ 0
Number of directors equity holders can elect \| segment		1
Exercise period					30 days
Common stock, shares authorized (in shares)	470,000,000		450,000,000	470,000,000	470,000,000	470,000,000		200,000,000
Common stock, par value (in dollars per share) \| $ / shares	$ 0.0001		$ 0.01	$ 0.0001	$ 0.0001	$ 0.0001
Common stock, shares Issued (in shares)	207,500,000		207,282,000	207,500,000	207,500,000	207,400,000
Common stock, shares outstanding (in shares)	198,400,000		196,643,000	198,400,000	198,400,000	197,400,000
Shares issued to Wilco Holdco stockholders (in shares)			130,300,000
Exchange ratio			136.7
Tax withholdings related to net share settlement of restricted stock awards (in shares)					50,000
Treasury stock (in shares)	80,000			80,000	80,000
Treasury stock, value \| $	$ 100,000			$ 100,000	$ 100,000
2016 Plan
Class of Stock [Line Items]
Unrestricted shares ( in shares)			1,200,000
Series I Warrants
Class of Stock [Line Items]
Number of outstanding warrants (in shares)		5,200,000
Exercise price of warrant (in dollars per share) \| $ / shares		$ 3
Proceeds from issuance of warrants \| $		$ 5,101,000
Issuance discount \| $		$ 200,000
Series II Warrants
Class of Stock [Line Items]
Number of outstanding warrants (in shares)		6,300,000
Exercise price of warrant (in dollars per share) \| $ / shares		$ 0.01
Proceeds from issuance of warrants \| $		$ 15,232,000
Issuance discount \| $		$ 500,000
Series A Preferred
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)	165,000	165,000		165,000	165,000
Preferred stock, par value (dollars per share) \| $ / shares		$ 0.0001
Preferred stock, stated value (dollars per share) \| $ / shares		$ 1,000
Preferred stock, shares authorized (in shares)		1,000,000
Preferred stock, shares outstanding (in shares)	165,000			165,000	165,000
Proceeds from issuance of Series A Senior Preferred Stock \| $		$ 144,667,000
Issuance costs \| $		2,880,000
Issuance discount \| $		$ 1,447,000
Annual dividend rate		12%
Discount on dividends		1%
In-kind increasing percentage		1%
Dividend rate, occurrence, increase percent		2%
Dividends, preferred stock, paid-in-kind \| $					$ 17,900,000
Accumulated paid in-kind dividends \| $	$ 17,900,000			$ 17,876,000
Redemption value \| $	$ 182,876,000	$ 165,000,000		$ 182,876,000	$ 182,876,000
Change in voting rights, ADBITDA threshold \| $		$ 100,000,000
Change in voting rights, change in ownership percent		50.10%
Class A Common Stock
Class of Stock [Line Items]
Common stock, shares authorized (in shares)	470,000,000			470,000,000	470,000,000
Common stock, par value (in dollars per share) \| $ / shares	$ 0.0001			$ 0.0001	$ 0.0001
Common stock voting rights \| vote	1			1	1
Common stock, shares Issued (in shares)	207,500,000			207,500,000	207,500,000
Common stock, shares outstanding (in shares)	198,400,000			198,400,000	198,400,000
Shares issued to Wilco Holdco stockholders (in shares)			130,300,000
Shares issued to Wilco Holdco stockholders, value per share (in dollars per share) \| $ / shares			$ 0.0001
Unrestricted shares ( in shares)			128,300,000
Class A Common Stock \| 2016 Plan
Class of Stock [Line Items]
Restricted shares (in shares)			2,000,000
Class A Common Stock \| Series I Warrants
Class of Stock [Line Items]
Exercise period		5 years
Class A Common Stock \| Series II Warrants
Class of Stock [Line Items]
Exercise period		5 years

Mezzanine and Stockholders' E_4

Mezzanine and Stockholders' Equity - Components of Proceeds Related to the Series A Senior Preferred Stock (Details) - USD ($) $ in Thousands		12 Months Ended
	Feb. 24, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Gross proceeds allocated to Series A Senior Preferred Stock		$ 144,667	$ 0	$ 0
Series A Preferred
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Gross proceeds allocated to Series A Senior Preferred Stock	$ 144,667
Less: original issue discount	(1,447)
Less: issuance costs	(2,880)
Net proceeds received from issuance of Series A Senior Preferred Stock	$ 140,340

Mezzanine and Stockholders' E_5

Mezzanine and Stockholders' Equity - Aggregate Stated Value Of Series A Senior Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Thousands		10 Months Ended
	Dec. 31, 2022	Dec. 31, 2022	Feb. 24, 2022	Dec. 31, 2021
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred stock, shares issued (in shares)	200,000	200,000		0
Preferred stock, shares outstanding (in shares)	200,000	200,000		0
Stated value (dollars per share)	$ 1,108.34	$ 1,108.34
Series A Preferred
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Aggregate stated value, beginning		$ 165,000
Accumulated paid in-kind dividends	$ 17,900	17,876
Aggregate stated value, ending	$ 182,876	$ 182,876
Preferred stock, shares issued (in shares)	165,000	165,000	165,000
Preferred stock, shares outstanding (in shares)	165,000	165,000
Stated value (dollars per share)			$ 1,000

Mezzanine and Stockholders' E_6

Mezzanine and Stockholders' Equity - Components of Proceeds Related to the Warrants (Details) - USD ($) $ in Thousands		12 Months Ended
	Feb. 24, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Gross proceeds allocated to 2022 Warrants	$ 20,333	$ 20,333	$ 0	$ 0
Less: original issue discount	(203)
Less: issuance costs	(405)
Net proceeds received from issuance of 2022 Warrants	19,725	$ 19,725
Series I Warrants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Gross proceeds allocated to 2022 Warrants	5,101
Less: original issue discount	(51)
Less: issuance costs	(102)
Net proceeds received from issuance of 2022 Warrants	4,948
Series II Warrants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Gross proceeds allocated to 2022 Warrants	15,232
Less: original issue discount	(152)
Less: issuance costs	(303)
Net proceeds received from issuance of 2022 Warrants	$ 14,777

Mezzanine and Stockholders' E_7

Mezzanine and Stockholders' Equity - Reserved Shares (Details) - shares shares in Thousands	Jun. 16, 2021	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance (in shares)		65,941
Shares available for grant under the 2021 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance (in shares)		10,862
Earnout Shares reserved
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance (in shares)		15,000
2022 Warrants outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance (in shares)		11,498
IPO Warrants outstanding
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance (in shares)		9,867
Vesting Shares reserved
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance (in shares)		8,625
Restricted shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance (in shares)		402
2016 Plan \| Common Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares (in shares)	2,000
2021 Plan \| Shares available for grant under the 2021 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance (in shares)		9,687

Wilco Holdco Redeemable Prefe_2

Wilco Holdco Redeemable Preferred Stock (Details) - USD ($) shares in Millions		12 Months Ended
	May 10, 2016	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Jun. 16, 2021
Class of Stock [Line Items]
Proceeds from issuance of Series A Senior Preferred Stock		$ 144,667,000	$ 0	$ 0
Loss on settlement of redeemable preferred stock		$ 0	14,037,000	0
Dividends paid, preferred stock			0	0
Class A Common Stock
Class of Stock [Line Items]
Equity consideration transferred in exchange for redemption of preferred stock					$ 59,000,000
Equity consideration transferred in exchange for redemption of preferred stock (in shares)					12.8
Wilco Holdco, Inc.
Class of Stock [Line Items]
Proceeds from issuance of Series A Senior Preferred Stock	$ 98,000,000
Annual dividend rate	10.25%
Quarterly increase in dividend rate after second anniversary	0.25%
Cumulative preferred dividends			$ 10,100,000	$ 19,000,000

IPO Warrant Liability - Narrati

IPO Warrant Liability - Narrative (Details) - $ / shares shares in Millions		12 Months Ended
	Jun. 16, 2021	Dec. 31, 2022
Class of Warrant or Right [Line Items]
Exercise price of warrant (in dollars per share)		$ 11.50
Exercise period		30 days
Expiration period		5 years
Public Warrant
Class of Warrant or Right [Line Items]
Number of shares called by each warrant	6.9	6.9
Private Placement Warrant
Class of Warrant or Right [Line Items]
Number of shares called by each warrant	3	3
Period that warrants are not transferable, assignable, or salable	30 days

IPO Warrant Liability - Warrant

IPO Warrant Liability - Warrant Liability (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	$ 4,341
Change in fair value of warrant liability	(4,243)	$ (22,595)	$ 0
Fair value, end of period	98	4,341
Private Placement Warrant
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	1,305	8,099
Change in fair value of warrant liability	(1,276)	(6,794)
Fair value, end of period	29	1,305	8,099
Public Warrant
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	3,036	18,837
Change in fair value of warrant liability	(2,967)	(15,801)
Fair value, end of period	$ 69	$ 3,036	$ 18,837

Contingent Common Shares Liab_3

Contingent Common Shares Liability - Narrative (Details)	Jun. 16, 2021 day tranche $ / shares shares
Earnout Shares
Derivative [Line Items]
Contingent consideration liability (in shares) \| shares	15,000,000
Contingent common share liability term	10 years
First Issuance, Earnout Shares
Derivative [Line Items]
Contingent consideration liability (in shares) \| shares	5,000,000
Threshold consecutive trading days (in days)	10
Threshold of trading days above stock price trigger (in days)	5
First Issuance, Earnout Shares \| Weighted Average
Derivative [Line Items]
Stock price trigger (in dollars per share) \| $ / shares	$ 12
Second Issuance, Earnout Shares
Derivative [Line Items]
Contingent consideration liability (in shares) \| shares	5,000,000
Threshold consecutive trading days (in days)	10
Threshold of trading days above stock price trigger (in days)	5
Second Issuance, Earnout Shares \| Weighted Average
Derivative [Line Items]
Stock price trigger (in dollars per share) \| $ / shares	$ 14
Third Issuance, Earnout Shares
Derivative [Line Items]
Contingent consideration liability (in shares) \| shares	5,000,000
Threshold consecutive trading days (in days)	10
Threshold of trading days above stock price trigger (in days)	5
Third Issuance, Earnout Shares \| Weighted Average
Derivative [Line Items]
Stock price trigger (in dollars per share) \| $ / shares	$ 16
Vesting Shares
Derivative [Line Items]
Contingent consideration liability (in shares) \| shares	8,600,000
Contingent common share liability term	10 years
Number of tranches \| tranche	3
First Issuance, Vesting Shares
Derivative [Line Items]
Contingent consideration liability (in shares) \| shares	2,900,000
Threshold consecutive trading days (in days)	10
Threshold of trading days above stock price trigger (in days)	5
First Issuance, Vesting Shares \| Weighted Average
Derivative [Line Items]
Stock price trigger (in dollars per share) \| $ / shares	$ 12
Second Issuance, Vesting Shares
Derivative [Line Items]
Contingent consideration liability (in shares) \| shares	2,900,000
Threshold consecutive trading days (in days)	10
Threshold of trading days above stock price trigger (in days)	5
Second Issuance, Vesting Shares \| Weighted Average
Derivative [Line Items]
Stock price trigger (in dollars per share) \| $ / shares	$ 14
Third Issuance, Vesting Shares
Derivative [Line Items]
Contingent consideration liability (in shares) \| shares	2,900,000
Threshold consecutive trading days (in days)	10
Threshold of trading days above stock price trigger (in days)	5
Third Issuance, Vesting Shares \| Weighted Average
Derivative [Line Items]
Stock price trigger (in dollars per share) \| $ / shares	$ 16

Contingent Common Shares Liab_4

Contingent Common Shares Liability - Derivatives and Fair Value (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Schedule of Changes in Fair Value
Fair value, beginning of period	$ 45,360
Fair value, end of period	2,835	$ 45,360
Earnout Shares
Schedule of Changes in Fair Value
Fair value, beginning of period	28,800	140,000
Changes in fair value(1)	(27,000)	(111,200)
Fair value, end of period	1,800	28,800
Vesting Shares
Schedule of Changes in Fair Value
Fair value, beginning of period	16,560	80,500
Changes in fair value(1)	(15,525)	(63,940)
Fair value, end of period	$ 1,035	$ 16,560

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) $ in Millions	Dec. 31, 2022 USD ($)	Dec. 31, 2021
Fair Value, Inputs, Level 3 \| Dividend yield
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Vesting Shares	0	0
Earnout Shares	0	0
Money Market Funds \| Fair Value, Inputs, Level 1
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash and cash equivalent, fair value disclosure	$ 30

Fair Value Measurements - Measu

Fair Value Measurements - Measurement Inputs (Details) - Fair Value, Inputs, Level 3	Dec. 31, 2022 $ / shares	Dec. 31, 2021 $ / shares
Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Earnout Shares	0.0388	0.0150
Vesting Shares	0.0388	0.0150
Volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Earnout Shares	0.7460	0.4486
Vesting Shares	0.7460	0.4486
Dividend yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Earnout Shares	0	0
Vesting Shares	0	0
Expected term (years)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Earnout Share, Term	8 years 6 months	9 years 6 months
Vesting Shares, Term	8 years 6 months	9 years 6 months
Share price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Earnout Shares	0.31	3.39
Vesting Shares	0.31	3.39

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2019
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 511,507	$ 901,117
Unrealized gain recognized in other comprehensive income before reclassifications	8,310	490
Reclassification to interest expense, net	(3,439)	1,445
Ending balance	48,447	511,507	$ 904,919
Cash Flow Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	28	(1,907)
Ending balance	$ 4,899	$ 28

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Fair Value of Derivative Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Other current assets
Derivatives designated as cash flow hedging instruments:
Assets	$ 5,028	$ 0
Other non-current assets
Derivatives designated as cash flow hedging instruments:
Assets	0	277
Accrued expenses and other liabilities
Derivatives designated as cash flow hedging instruments:
Liabilities	0	$ 288
Other non-current liabilities
Derivatives designated as cash flow hedging instruments:
Liabilities	$ 73

Income Taxes - Summary of Compa

Income Taxes - Summary of Company's Provision for Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Current:
Federal	$ 6	$ 0	$ 0
State	37	128	251
Total current	43	128	251
Deferred:
Federal	(37,634)	(60,002)	3,514
State	(10,939)	(11,086)	(1,700)
Total deferred	(48,573)	(71,088)	1,814
Total income tax (benefit) expense	$ (48,530)	$ (70,960)	$ 2,065

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
Income Taxes - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Contingency [Line Items]
Effect income tax rate (in percent)	9%	8.30%	(62.50%)
Reduction in unrecognized tax benefit	$ 0	$ 3,027	$ 0
Federal
Income Tax Contingency [Line Items]
Operating loss carryforwards	68,900	49,800
Valuation allowance period increase	25,800	22,500
State
Income Tax Contingency [Line Items]
Operating loss carryforwards	35,500	32,500
Valuation allowance period increase	$ 5,800	$ 13,300

Income Taxes - Differences Betw

Income Taxes - Differences Between The Federal Tax Rate And The Company's Effective Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Federal income tax benefit at statutory rate	$ (113,731)	$ (179,128)	$ (694)
State income tax (benefit) expense, net of federal tax benefit	(16,827)	(25,814)	1,248
Change in state tax rate	5	34	(2,551)
Prior period adjustments and other	167	1,515	(105)
Valuation allowance	31,595	35,731	(981)
Interest expense on redeemable preferred stock	0	2,118	3,997
Changes in fair value of warrant liability and contingent common shares liability	(9,821)	(41,524)	0
Goodwill impairment charges	59,893	132,447	0
Other permanent differences, net	189	3,661	1,151
Total income tax (benefit) expense	$ (48,530)	$ (70,960)	$ 2,065
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal income tax benefit at statutory rate	21%	21%	21%
State income tax (benefit) expense, net of federal tax benefit	3.10%	3%	(37.80%)
Change in state tax rate	0%	0%	77.10%
Prior period adjustments and other	0%	(0.20%)	3.20%
Valuation allowance	(5.80%)	(4.20%)	29.70%
Interest expense on redeemable preferred stock	0%	(0.20%)	(120.90%)
Changes in fair value of warrant liability and contingent common shares liability	1.80%	4.90%	0%
Goodwill impairment charges	(11.10%)	(15.50%)	0%
Other permanent differences, net	0%	(0.50%)	(34.80%)
Total income tax (benefit) expense	9%	8.30%	(62.50%)

Income Taxes - Schedule of Defe

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred income tax assets:
Accrued liabilities	$ 7,112	$ 10,420
Provision for bad debt	11,828	12,530
Operating lease liabilities	64,288	74,115
Acquisition and transaction costs	3,186	3,770
Net operating losses	104,419	82,304
Interest expense	43,323	33,163
Other deferred tax assets	6,335	4,798
Total gross deferred income tax assets	240,491	221,100
Valuation allowance	(89,907)	(58,312)
Total gross deferred income tax assets, net of valuation allowance	150,584	162,788
Deferred income tax liabilities:
Goodwill	26,251	26,563
Trade name/trademark	66,445	114,451
Operating lease right-of-use assets	54,360	63,252
Depreciation	20,039	22,089
Other deferred tax liabilities	2,375	3,892
Total gross deferred income tax liabilities	169,470	230,247
Net deferred income tax liabilities	$ 18,886	$ 67,459

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period	$ 0	$ 3,027	$ 2,341
Increases for positions taken during the year	0	0	686
Decreases for positions taken in prior years	0	(3,027)	0
Balance at end of period	$ 0	$ 0	$ 3,027

Leases - Narrative (Details)

Leases - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
Leases - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Total lease termination costs			$ 4,300
Loss on lease terminations	$ 0	$ 0	3,863
Other lease termination costs			400
Cash payments related to lease terminations	0	4,570	$ 0
Operating lease assets additions	13,700	18,400
Operating lease liabilities, additions	$ 13,700	$ 18,400
Minimum
Lessee, Lease, Description [Line Items]
Initial operating lease term	7 years
Maximum
Lessee, Lease, Description [Line Items]
Initial operating lease term	10 years

Leases - Lease Cost (Details)

Leases - Lease Cost (Details) - USD ($) $ in Thousands	12 Months Ended
Leases - Lease Cost (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Operating lease cost	$ 69,533	$ 65,555	$ 67,279
Variable lease cost	20,951	20,045	18,689
Total lease cost	90,484	85,600	85,968
Goodwill, intangible and other asset impairment charges	486,262	962,303	$ 0
ROU asset impairment charges	$ 2,600	$ 1,200

Leases - Supplemental Cash Flow

Leases - Supplemental Cash Flow (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 72,440	$ 65,678	$ 61,993
Cash payments related to lease terminations	0	4,570	0
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 9,688	$ 28,759	$ 14,067

Leases - Other Information (Det

Leases - Other Information (Details)	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Weighted-average remaining lease term: Operating leases	5 years 10 months 24 days	6 years 4 months 24 days
Weighted-average discount rate: Operating leases	690%	650%

Leases - Maturity (Details)

Leases - Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
2023	$ 64,066
2024	61,885
2025	52,459
2026	46,069
2027	35,108
Thereafter	68,006
Total undiscounted future cash flows	327,593
Less: Imputed Interest	(61,493)
Present value of future cash flows	266,100
Presentation on Balance Sheet
Current	47,676	$ 49,433
Non-current	218,424	$ 250,597
Disposal Group, Held-for-sale, Not Discontinued Operations \| 2022 Clinics Held for Sale
Presentation on Balance Sheet
Current portion of operating lease liabilities	685
Operating lease liabilities	$ 1,706

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Millions		10 Months Ended	12 Months Ended
Commitments and Contingencies (Details) $ in Millions	Aug. 16, 2021 plaintiff	Sep. 22, 2022 plaintiff	Dec. 31, 2022 USD ($) shares	Nov. 21, 2022 segment	Dec. 31, 2021 shares	Jun. 16, 2021 shares	Jun. 15, 2021 shares
Loss Contingencies [Line Items]
Contractual obligation \| $			$ 7.2
Common stock, shares authorized (in shares) \| shares			470,000,000		470,000,000	450,000,000	200,000,000
Number of plaintiffs who filed consolidated amended complaint \| segment				4
Payor Dispute
Loss Contingencies [Line Items]
Loss on litigation settlement \| $			$ 3
ATI Shareholders vs ATI Individual Defendants
Loss Contingencies [Line Items]
Number of plaintiffs	2
Derivative Action
Loss Contingencies [Line Items]
Number of plaintiffs		5
Claims filed		4

Loss per Share - Loss per Share

Loss per Share - Loss per Share Calculation (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Basic and diluted loss per share:
Net loss	$ (493,047)	$ (782,028)	$ (298)
Less: Net (loss) income attributable to non-controlling interests	(668)	(3,700)	5,073
Less: Series A Senior Preferred cumulative dividend	17,876	0	0
Loss available to common stockholders, basic	(510,255)	(778,328)	(5,371)
Loss available to common stockholders, diluted	$ (510,255)	$ (778,328)	$ (5,371)
Weighted average shares outstanding, basic (in shares)	203,150,000	165,805,000	128,286,000
Weighted average shares outstanding, diluted (in shares)	203,150,000	165,805,000	128,286,000
Basic loss per share (in dollars per share)	$ (2.51)	$ (4.69)	$ (0.04)
Diluted loss per share (in dollars per share)	$ (2.51)	$ (4.69)	$ (0.04)

Loss per Share - Antidilutive S

Loss per Share - Antidilutive Securities (Details) - shares		12 Months Ended
Loss per Share - Antidilutive Securities (Details) - shares	Jun. 16, 2021	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total antidilutive securities (in shares)		25,183,000	12,817,000	0
Earnout Shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Contingent consideration liability (in shares)	15,000,000
Vesting Shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Contingent consideration liability (in shares)	8,600,000
2016 Plan \| Common Class A
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Restricted shares (in shares)	2,000,000
Series I Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total antidilutive securities (in shares)		5,226,000	0	0
IPO Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total antidilutive securities (in shares)		9,867,000	9,867,000	0
Restricted shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total antidilutive securities (in shares)		175,000	448,000	0
Restricted shares \| Wilco Holdco, Inc.
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total antidilutive securities (in shares)		402,000	1,323,000	0
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total antidilutive securities (in shares)		5,313,000	775,000	0
RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total antidilutive securities (in shares)		4,200,000	404,000	0

Schedule II - Valuation and Q_2

Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Allowance for doubtful accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 53,533	$ 69,693	$ 80,350
Additions	13,869	16,369	16,231
Deductions/ Adjustments	(19,782)	(32,529)	(26,888)
Balance at End of Year	47,620	53,533	69,693
Valuation allowance for deferred tax assets
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	58,312	22,581	23,562
Additions	31,595	35,731	0
Deductions/ Adjustments	0	0	(981)
Balance at End of Year	$ 89,907	$ 58,312	$ 22,581