Equity Commonwealth (EQC) 10-Q24 Oct 242024 Q3 Quarterly reportFinancial data

Company Profile

Cover Page

Cover Page - shares	9 Months Ended
Cover Page - shares	Sep. 30, 2024	Oct. 18, 2024
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2024
Document Transition Report	false
Entity File Number	1-9317
Entity Registrant Name	EQUITY COMMONWEALTH
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	04-6558834
Entity Address, Address Line One	Two North Riverside Plaza, Suite 2000
Entity Address, City or Town	Chicago
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60606
City Area Code	(312)
Local Phone Number	646-2800
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		107,334,031
Entity Central Index Key	0000803649
Amendment Flag	false
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Common Shares of Beneficial Interest
Document Information [Line Items]
Title of 12(b) Security	Common Shares of Beneficial Interest
Trading Symbol	EQC
Security Exchange Name	NYSE
6.50% Series D Cumulative Convertible Preferred Shares of Beneficial Interest
Document Information [Line Items]
Title of 12(b) Security	6.50% Series D Cumulative Convertible Preferred Shares of Beneficial Interest
Trading Symbol	EQCpD
Security Exchange Name	NYSE

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Real estate properties:
Land	$ 22,400	$ 44,060
Buildings and improvements	158,152	367,827
Total real estate properties, at cost, gross	180,552	411,887
Accumulated depreciation	(69,254)	(180,535)
Total real estate properties, at cost, net	111,298	231,352
Assets held for sale	86,803	0
Cash and cash equivalents	2,225,150	2,160,535
Rents receivable	8,046	15,737
Other assets, net	9,833	17,417
Total assets	2,441,130	2,425,041
LIABILITIES AND EQUITY
Liabilities related to properties held for sale	6,200	0
Accounts payable, accrued expenses and other	17,621	27,298
Rent collected in advance	1,324	1,990
Distributions payable	2,803	5,640
Total liabilities	27,948	34,928
Shareholders’ equity:
Series D preferred shares; 6.50% cumulative convertible; $4,915,196 shares issued and outstanding, aggregate liquidation preference of $122,880	119,263	119,263
Common shares of beneficial interest, $0.01 par value: $350,000,000 shares authorized; $107,327,691 and $106,847,438 shares issued and outstanding, respectively	1,073	1,068
Additional paid in capital	3,942,389	3,935,873
Cumulative net income	3,950,345	3,926,979
Cumulative common distributions	(4,863,688)	(4,864,440)
Cumulative preferred distributions	(739,667)	(733,676)
Total shareholders’ equity	2,409,715	2,385,067
Noncontrolling interest	3,467	5,046
Total equity	2,413,182	2,390,113
Total liabilities and equity	$ 2,441,130	$ 2,425,041

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Preferred shares of beneficial interest, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred shares of beneficial interest, shares authorized (in shares)	50,000,000	50,000,000
Preferred shares, dividend percentage	6.50%	6.50%
Preferred shares of beneficial interest, shares issued (in shares)	4,915,196	4,915,196
Preferred shares, of beneficial interest, shares outstanding (in shares)	4,915,196	4,915,196
Preferred shares, aggregate liquidation preference	$ 122,880	$ 122,880
Common shares of beneficial interest, par value (in dollars per share)	$ 0.01	$ 0.01
Common shares of beneficial interest, shares authorized (in shares)	350,000,000	350,000,000
Common shares of beneficial interest, shares issued (in shares)	107,327,691	106,847,438
Common shares of beneficial interest, shares outstanding (in shares)	107,327,691	106,847,438

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Revenues:
Rental revenue	$ 12,782	$ 13,928	$ 39,491	$ 41,512
Other revenue	1,206	1,284	3,796	3,866
Total revenues	13,988	15,212	43,287	45,378
Expenses:
Operating expenses	6,863	6,722	20,118	20,920
Depreciation and amortization	4,214	4,436	12,753	13,260
General and administrative	8,886	7,061	25,565	29,470
Loss on asset impairment	50,226	0	50,226	0
Total expenses	70,189	18,219	108,662	63,650
Interest and other income, net	29,996	29,269	89,278	84,997
(Loss) income before income taxes	(26,205)	26,262	23,903	66,725
Income tax expense	(22)	(30)	(486)	(1,906)
Net (loss) income	(26,227)	26,232	23,417	64,819
Net loss (income) attributable to noncontrolling interest	38	(86)	(51)	(204)
Net (loss) income attributable to Equity Commonwealth	(26,189)	26,146	23,366	64,615
Preferred distributions	(1,997)	(1,997)	(5,991)	(5,991)
Net (loss) income attributable to Equity Commonwealth common shareholders	$ (28,186)	$ 24,149	$ 17,375	$ 58,624
Weighted average common shares outstanding — basic (in shares)	107,456	108,931	107,363	109,494
Weighted average common shares outstanding — diluted (in shares)	107,456	110,217	108,391	110,916
Earnings per common share attributable to Equity Commonwealth common shareholders:
Basic (in dollars per share)	$ (0.26)	$ 0.22	$ 0.16	$ 0.54
Diluted (in dollars per share)	(0.26)	0.22	0.16	0.53
Distributions declared per common share (in dollars per share)	$ 0	$ 0	$ 0	$ 4.25

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Series D Preferred Shares	Common Shares	Additional Paid in Capital	Cumulative Net Income	Cumulative Common Distributions	Cumulative Preferred Distributions	Noncontrolling Interest
Balance as of beginning of period (in shares) at Dec. 31, 2022		4,915,196	109,428,252
Balance as of beginning of period at Dec. 31, 2022	$ 2,823,732	$ 119,263	$ 1,094	$ 3,979,566	$ 3,835,815	$ (4,393,522)	$ (725,688)	$ 7,204
Increase (Decrease) in Stockholders' Equity
Net income	64,819				64,615			204
Share-based compensation (in shares)			436,398
Share-based compensation	13,476		$ 4	10,807				2,665
Distributions	(479,593)					(471,668)	(5,991)	(1,934)
Adjustment for noncontrolling interest	0			166				(166)
Surrender of shares for tax withholding (in shares)			(134,193)
Surrender of shares for tax withholding	(3,395)		$ (1)	(3,394)
Repurchase of shares (in shares)			(3,018,411)
Repurchase of shares	(56,803)		$ (30)	(56,773)
Balance as of end of period (in shares) at Sep. 30, 2023		4,915,196	106,712,046
Balance as of end of period at Sep. 30, 2023	2,362,236	$ 119,263	$ 1,067	3,930,372	3,900,430	(4,865,190)	(731,679)	7,973
Balance as of beginning of period (in shares) at Jun. 30, 2023		4,915,196	109,730,457
Balance as of beginning of period at Jun. 30, 2023	2,391,827	$ 119,263	$ 1,097	3,984,681	3,874,284	(4,865,668)	(729,682)	7,852
Increase (Decrease) in Stockholders' Equity
Net income	26,232				26,146			86
Share-based compensation	2,499			2,447				52
Distributions	(1,519)					478	(1,997)
Adjustment for noncontrolling interest	0			17				(17)
Repurchase of shares (in shares)			(3,018,411)
Repurchase of shares	(56,803)		$ (30)	(56,773)
Balance as of end of period (in shares) at Sep. 30, 2023		4,915,196	106,712,046
Balance as of end of period at Sep. 30, 2023	2,362,236	$ 119,263	$ 1,067	3,930,372	3,900,430	(4,865,190)	(731,679)	7,973
Balance as of beginning of period (in shares) at Dec. 31, 2023		4,915,196	106,847,438
Balance as of beginning of period at Dec. 31, 2023	2,390,113	$ 119,263	$ 1,068	3,935,873	3,926,979	(4,864,440)	(733,676)	5,046
Increase (Decrease) in Stockholders' Equity
Net income	23,417				23,366			51
Share-based compensation (in shares)			564,297
Share-based compensation	7,947		$ 6	7,787				154
Distributions	(5,239)					752	(5,991)
Adjustment for noncontrolling interest	0			340				(340)
Surrender of shares for tax withholding (in shares)			(161,837)
Surrender of shares for tax withholding	(3,056)		$ (2)	(3,054)
OP unit redemption (in shares)			77,793
OP Unit redemption	0		$ 1	1,443				(1,444)
Balance as of end of period (in shares) at Sep. 30, 2024		4,915,196	107,327,691
Balance as of end of period at Sep. 30, 2024	2,413,182	$ 119,263	$ 1,073	3,942,389	3,950,345	(4,863,688)	(739,667)	3,467
Balance as of beginning of period (in shares) at Jun. 30, 2024		4,915,196	107,327,691
Balance as of beginning of period at Jun. 30, 2024	2,437,787	$ 119,263	$ 1,073	3,939,583	3,976,534	(4,864,499)	(737,670)	3,503
Increase (Decrease) in Stockholders' Equity
Net income	(26,227)				(26,189)			(38)
Share-based compensation	2,758			2,705				53
Distributions	(1,136)					811	(1,997)	50
Adjustment for noncontrolling interest	0			101				(101)
Balance as of end of period (in shares) at Sep. 30, 2024		4,915,196	107,327,691
Balance as of end of period at Sep. 30, 2024	$ 2,413,182	$ 119,263	$ 1,073	$ 3,942,389	$ 3,950,345	$ (4,863,688)	$ (739,667)	$ 3,467

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 23,417	$ 64,819
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	10,894	11,353
Straight-line rental income	(559)	445
Other amortization	1,859	1,907
Amortization of right-of-use asset	126	0
Share-based compensation	7,947	13,476
Loss on asset impairment	50,226	0
Change in assets and liabilities:
Rents receivable and other assets	(1,907)	(1,082)
Accounts payable, accrued expenses and other	(4,328)	(4,253)
Rent collected in advance	779	(222)
Net cash provided by operating activities	88,454	86,443
CASH FLOWS FROM INVESTING ACTIVITIES:
Real estate improvements	(12,706)	(4,613)
Cash used in investing activities	(12,706)	(4,613)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repurchase and retirement of common shares	(3,056)	(60,198)
Distributions to common shareholders	(2,036)	(468,232)
Distributions to preferred shareholders	(5,991)	(5,991)
Distributions to holders of noncontrolling interest	(50)	(1,843)
Net cash used in financing activities	(11,133)	(536,264)
Increase (decrease) in cash and cash equivalents	64,615	(454,434)
Cash and cash equivalents at beginning of period	2,160,535	2,582,222
Cash and cash equivalents at end of period	2,225,150	2,127,788
SUPPLEMENTAL CASH FLOW INFORMATION:
Taxes paid, net	182	1,946
Recognition of right-of-use asset and lease liability	873	0
NON-CASH INVESTING ACTIVITIES:
Accrued capital expenditures	1,621	1,819
NON-CASH FINANCING ACTIVITIES:
Distributions payable	2,803	6,390
OP Unit redemption	$ 1,444	$ 0

Business

Business	9 Months Ended
Business	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business	Business Equity Commonwealth, or the Company, is a real estate investment trust, or REIT, formed in 1986 under the laws of the State of Maryland. Our business is primarily the ownership and operation of office properties in the United States. The Company operates in an umbrella partnership real estate investment trust, or UPREIT, and conducts substantially all of its activities through EQC Operating Trust, a Maryland real estate investment trust, or the Operating Trust. The Company beneficially owned 99.86% of the outstanding shares of beneficial interest, designated as units, in the Operating Trust, or OP Units, as of September 30, 2024, and the Company is the sole trustee of the Operating Trust. As the sole trustee, the Company generally has the power under the declaration of trust of the Operating Trust to manage and conduct the business of the Operating Trust, subject to certain limited approval and voting rights of other holders of OP Units. On October 2, 2024 the Company filed a definitive proxy statement, the Definitive Proxy, with the U.S. Securities and Exchange Commission related to a Special Meeting of Shareholders, the Special Shareholder Meeting, for the following purposes: (i) to consider and vote upon the Plan of Sale and Dissolution of the Company, the Plan of Sale, including the wind-down and complete liquidation of the Company, and the dissolution and termination of the Company, including the establishment of a Liquidating Entity (as defined in the Definitive Proxy), and (ii) on an advisory, non-binding basis, to consider and vote upon compensation that may become payable by the Company to its named executive officers in connection with the Plan of Sale. The Plan of Sale, which the Company’s Board of Trustees has determined is in the best interests of the Company and its shareholders, authorizes the Company to sell all of its remaining properties, wind-down the Company’s affairs and distribute the net proceeds to shareholders. As disclosed in the Definitive Proxy, the Special Shareholder Meeting is scheduled to be held virtually on November 12, 2024 for shareholders of record at the close of business on October 1, 2024. If the Plan of Sale is approved by the Company's shareholders, the Company will adopt the liquidation basis of accounting which requires the Company's assets to be recognized at the estimated amounts expected to be collected and liabilities to be recognized at the estimated amounts at which they are expected to be settled. At September 30, 2024, our portfolio consisted of four properties (eight buildings), with a combined 1.5 million square feet, and we had $2.2 billion of cash and cash equivalents.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
Summary of Significant Accounting Policies	Sep. 30, 2024
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The accompanying condensed consolidated financial statements of EQC have been prepared without audit. Certain information and footnote disclosures required by U.S. generally accepted accounting principles, or GAAP, for complete financial statements have been condensed or omitted. We believe the disclosures made are appropriate. The accompanying condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes contained in our Annual Report on Form 10-K, or our Annual Report, for the year ended December 31, 2023. Capitalized terms used, but not defined in this Quarterly Report, have the same meanings as in our Annual Report. In the opinion of our management, all adjustments, which include only normal recurring adjustments considered necessary for a fair presentation, have been included. All intercompany transactions and balances with or among our subsidiaries have been eliminated. Operating results for interim periods are not necessarily indicative of the results that may be expected for the full year. The preparation of financial statements in conformity with GAAP requires us to make estimates and assumptions that affect reported amounts. Actual results could differ from those estimates. Significant estimates in the condensed consolidated financial statements include the assessment of the collectability of rental revenue, purchase price allocations, useful lives of fixed assets and impairment of real estate and intangible assets. Dollar amounts presented may be approximate. Share amounts are presented in whole numbers, except where noted. New Accounting Pronouncements In November 2023, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, which improves the disclosures about a public entity's reportable segments and addresses requests from investors for additional, more detailed information about a reportable segment's expenses. This update is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. We do not expect the adoption of ASU 2023-07 to have a material impact on our consolidated financial statements. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which enhances the transparency and decision usefulness of income tax disclosures. This update is effective for annual periods beginning after December 15, 2024. Early adoption is permitted for annual financial statements that have not yet been issued or made available for issuance. We do not expect the adoption of ASU 2023-09 to have a material impact on our consolidated financial statements.

Real Estate Properties

Real Estate Properties	9 Months Ended
Real Estate Properties	Sep. 30, 2024
Real Estate [Abstract]
Real Estate Properties	Real Estate Properties During the nine months ended September 30, 2024 and 2023, we made improvements, excluding tenant-funded improvements, to our properties totaling $11.4 million and $5.5 million, respectively. Properties Held for Sale We classify all properties that meet the criteria outlined in FASB Accounting Standards Codification 360, Property, Plant and Equipment as held for sale on our condensed consolidated balance sheets. As of December 31, 2023, we did not have any properties classified as held for sale. As of September 30, 2024, we classified the following properties as held for sale: Asset Number of Properties Number of Buildings Square 1250 H Street, NW 1 1 196,490 206 East 9th Street (Capitol Tower) 1 1 175,510 Bridgepoint Square 1 5 440,007 3 7 812,007 Summarized balance sheet information for the properties classified as held for sale is as follows (in thousands): September 30, 2024 Real estate properties $ 86,707 Other assets, net 96 Properties held for sale $ 86,803 Accounts payable and accrued expenses $ 4,755 Rent collected in advance 1,445 Liabilities related to properties held for sale $ 6,200 Lease Payments Rental revenue consists of the following (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Lease payments $ 8,470 $ 9,115 $ 25,908 $ 26,878 Variable lease payments 4,312 4,813 13,583 14,634 Rental revenue $ 12,782 $ 13,928 $ 39,491 $ 41,512

Shareholders' Equity

Shareholders' Equity	9 Months Ended
Shareholders' Equity	Sep. 30, 2024
Stockholders' Equity Note [Abstract]
Shareholders' Equity	Shareholders’ Equity Common Share Issuances See Note 7 for information regarding equity issuances related to share-based compensation. Common Share Repurchases On June 18, 2024, our Board of Trustees authorized the repurchase of up to $150.0 million of our outstanding common shares from July 1, 2024 through June 30, 2025. We did not repurchase any common shares under our share repurchase program during the nine months ended September 30, 2024. As of September 30, 2024, we had $150.0 million of remaining availability under our share repurchase program, which expires on June 30, 2025. During the nine months ended September 30, 2024 and 2023, certain of our employees and former employees surrendered 161,837 and 134,193 common shares owned by them, respectively, to satisfy their statutory tax withholding obligations in connection with the vesting of such common shares pursuant to our equity compensation plans. Common Share Distributions In February 2024, the number of earned awards for recipients of the Company’s restricted stock units granted in January 2021 was determined. Pursuant to the terms of such awards, we paid one-time catch-up cash distributions to these recipients in the aggregate amount of $2.0 million, for distributions to common shareholders declared by our Board of Trustees during such awards’ performance measurement period. Preferred Share Distributions In 2024, our Board of Trustees declared distributions on our series D preferred shares to date as follows: Declaration Date Record Date Payment Date Series D Dividend Per Share January 16, 2024 January 31, 2024 February 15, 2024 $ 0.40625 April 16, 2024 April 30, 2024 May 15, 2024 $ 0.40625 July 16, 2024 July 31, 2024 August 15, 2024 $ 0.40625 October 16, 2024 October 31, 2024 November 15, 2024 $ 0.40625

Noncontrolling Interest

Noncontrolling Interest	9 Months Ended
Noncontrolling Interest	Sep. 30, 2024
Noncontrolling Interest [Abstract]
Noncontrolling Interest	Noncontrolling Interest Noncontrolling interest represents the portion of the OP Units not beneficially owned by the Company. The ownership of an OP Unit and a common share of beneficial interest have essentially the same economic characteristics. Distributions with respect to OP Units will generally mirror distributions with respect to the Company’s common shares. Unitholders (other than the Company) generally have the right, commencing six months from the date of issuance of such OP Units, to cause the Operating Trust to redeem their OP Units in exchange for cash or, at the option of the Company, common shares of the Company on a one-for-one basis. As sole trustee, the Company has the sole discretion to elect whether the redemption right will be satisfied by the Company in cash or the Company’s common shares. As a result, the Noncontrolling interest is classified as permanent equity. As of September 30, 2024, the portion of the Operating Trust not beneficially owned by the Company is in the form of OP Units and LTIP Units (see Note 7 for a description of LTIP Units). LTIP Units may be subject to additional vesting requirements. The following table presents the changes in Equity Commonwealth’s issued and outstanding common shares and units for the nine months ended September 30, 2024: Common Shares OP Units and LTIP Units Total Outstanding at January 1, 2024 106,847,438 226,018 107,073,456 Repurchase and surrender of shares (161,837) — (161,837) OP Unit redemption 77,793 (77,793) — Share-based compensation grants and vesting, net of forfeitures 564,297 6,218 570,515 Outstanding at September 30, 2024 107,327,691 154,443 107,482,134 Noncontrolling ownership interest in the Operating Trust 0.14 % The carrying value of the Noncontrolling interest is allocated based on the number of OP Units and LTIP Units in proportion to the number of OP Units and LTIP Units plus the number of common shares. We adjust the Noncontrolling interest balance at the end of each period to reflect the noncontrolling partners’ interest in the net assets of the Operating Trust. Net income is allocated to the Noncontrolling interest in the Operating Trust based on the weighted average ownership percentage during the period. Equity Commonwealth’s weighted average ownership interest in the Operating Trust was 99.86% and 99.83% for the three and nine months ended September 30, 2024, respectively.

Income Taxes

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2024
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We have elected to be taxed as a REIT under the Internal Revenue Code of 1986, as amended, and are generally not subject to federal and state income taxes provided we distribute a sufficient amount of our taxable income to our shareholders and meet other requirements for qualifying as a REIT. However, we are subject to certain state and local taxes without regard to our REIT status. Our provision for income taxes consists of the following (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Current: State and local $ (22) $ (30) $ (486) $ (90) Federal — — — (1,816) Income tax expense $ (22) $ (30) $ (486) $ (1,906) Federal income tax expense in the 2023 period relates to federal income taxes at our taxable REIT subsidiary.

Share-Based Compensation

Share-Based Compensation	9 Months Ended
Share-Based Compensation	Sep. 30, 2024
Share-Based Payment Arrangement [Abstract]
Share-Based Compensation	Share-Based Compensation Recipients of the Company’s restricted shares have the same voting rights as any other common shareholder. During the period of restriction, holders of unvested restricted shares are eligible to receive dividend payments on their shares at the same rate and on the same date as any other common shareholder. The restricted shares are service based awards and vest over a service period determined by the Compensation Committee of our Board of Trustees, or the Compensation Committee. Recipients of the Company’s restricted stock units, or RSUs, are entitled to receive dividends with respect to the common shares underlying the RSUs if and when the RSUs are earned, at which time the recipient will be entitled to receive an amount in cash equal to the aggregate amount of cash dividends that would have been paid in respect to the common shares underlying the recipient’s earned RSUs had such common shares been issued to the recipient on the first day of the performance period. To the extent that an award does not vest, the dividends related to unvested RSUs will be forfeited. The RSUs are market-based awards with a service condition and recipients may earn RSUs based on the Company’s total shareholder return, or TSR, relative to the TSRs of the companies that comprise the Nareit Office Index over a three-year performance period. Following the end of the three-year performance period, the number of earned awards will be determined. The earned awards vest in two tranches with 50% of the earned award vesting following the end of the performance period on the date the Compensation Committee determines the level of achievement of the performance metric and the remaining 50% of the earned award vesting approximately one year thereafter, subject to the grant recipient’s continued employment. Compensation expense for the RSUs is determined using a Monte Carlo simulation model and is recognized ratably from the grant date to the vesting date of each tranche. LTIP Units are a class of beneficial interests in the Operating Trust that may be issued to employees, officers or trustees of the Operating Trust, the Company or their subsidiaries. Time-based LTIP Units have the same general characteristics as restricted shares and market-based LTIP Units have the same general characteristics as RSUs. Each LTIP Unit will convert automatically into an OP Unit on a one-for-one basis when the LTIP Unit becomes vested and its capital account is equalized with the per-unit capital account of the OP Units. Holders of LTIP Units generally will be entitled to receive the same per-unit distributions as the other outstanding OP Units in the Operating Trust, except that market-based LTIP Units will not participate in distributions until expiration of the applicable performance period, at which time any earned market-based LTIP Units generally will become entitled to receive a catch-up distribution for the periods prior to such time. 2024 Equity Award Activity During the nine months ended September 30, 2024, 391,061 RSUs vested, and, as a result, we issued 391,061 common shares, prior to certain employees surrendering their common shares to satisfy tax withholding obligations (see Note 4). On January 29, 2024, the Compensation Committee approved grants in the aggregate amount of 142,146 restricted shares and 288,596 RSUs at target (719,326 RSUs at maximum) to the Company’s officers and certain employees, as part of their compensation for fiscal year 2023. The restricted shares were valued at $19.36 per share, the closing price of our common shares on the New York Stock Exchange, or the NYSE, on the grant date. The assumptions and fair value for the RSUs granted during the nine months ended September 30, 2024 are included in the following table on a per share basis. 2024 Fair value of market-based awards granted $ 27.08 Expected term (years) 4 Expected volatility 15.46 % Risk-free rate 4.06 % On June 18, 2024, in accordance with the Company’s compensation program for independent Trustees, the Committee awarded each of the six independent Trustees $0.1 million in restricted shares or time-based LTIP Units as part of their compensation for the 2024-2025 year of service on the Board of Trustees. These awards equated to 6,218 shares or time-based LTIP Units per Trustee, for a total of 31,090 shares and 6,218 time-based LTIP Units, valued at $19.30 per share and unit, the closing price of our common shares on the NYSE on that day. These shares and time-based LTIP Units vest one year after the date of the award, on June 18, 2025. 2023 Equity Award Activity During the nine months ended September 30, 2023, 274,739 RSUs vested, and, as a result, we issued 274,739 common shares, prior to certain employees surrendering their common shares to satisfy tax withholding obligations. On January 26, 2023, the Compensation Committee approved grants in the aggregate amount of 132,794 restricted shares and 269,609 RSUs at target (672,000 RSUs at maximum) to the Company’s officers, certain employees, and to Mr. Zell, the former Chairman of our Board of Trustees, as part of their compensation for fiscal year 2022. The restricted shares were valued at $25.61 per share, the closing price of our common shares on the NYSE on the grant date. The RSUs were valued at $36.51 per share, their fair value on the grant date. On June 13, 2023, in accordance with the Company’s compensation program for independent Trustees, the Committee awarded each of the six independent Trustees $0.1 million in restricted shares or time-based LTIP Units as part of their compensation for the 2023-2024 year of service on the Board of Trustees. These awards equated to 5,773 shares or time-based LTIP Units per Trustee, for a total of 28,865 shares and 5,773 time-based LTIP Units, valued at $20.79 per share and unit, the closing price of our common shares on the NYSE on that day. These shares and time-based LTIP Units vested on June 13, 2024. Outstanding Equity Awards As of September 30, 2024, the estimated future compensation expense for all unvested restricted shares and time-based LTIP Units was $5.3 million. Compensation expense for the restricted share and time-based LTIP Unit awards is being recognized on a straight-line basis over the requisite service period for each separately vesting portion of the award. The weighted average period over which the future compensation expense will be recorded for the restricted shares and time-based LTIP Units is approximately 2.4 years. As of September 30, 2024, the estimated future compensation expense for all unvested RSUs and market-based LTIP Units was $12.0 million. The weighted average period over which the future compensation expense will be recorded for the RSUs and market-based LTIP Units is approximately 2.3 years. During the three months ended September 30, 2024 and 2023, we recorded $2.8 million and $2.5 million, respectively, and during the nine months ended September 30, 2024 and 2023, we recorded $8.0 million and $13.5 million, respectively, of compensation expense, net of forfeitures, in general and administrative expense for grants to our trustees, employees and an eligible consultant related to our equity compensation plans. Compensation expense recorded during the three and nine months ended September 30, 2024 includes $0.1 million and $0.1 million, respectively, of accelerated vesting due to staffing reductions. Compensation expense recorded during the three and nine months ended September 30, 2023 includes $0 and $5.2 million, respectively, of accelerated vesting due to the passing of our former Chairman in 2023. Forfeitures are recognized as they occur. At September 30, 2024, 1,406,557 shares/units remain available for issuance under the Equity Commonwealth 2015 Omnibus Incentive Plan, as amended.

Fair Value of Assets and Liabil

Fair Value of Assets and Liabilities	9 Months Ended
Fair Value of Assets and Liabilities	Sep. 30, 2024
Fair Value Disclosures [Abstract]
Fair Value of Assets and Liabilities	Fair Value of Assets and Liabilities Properties Held for Sale Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. A three-level valuation hierarchy exists for disclosures of fair value measurements based upon the transparency of inputs to the valuation of an asset or liability as of the measurement date. A financial instrument's categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. See Note 2 to the financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2023 for additional information. The three levels are defined below: • Level 1 - Quoted prices in active markets for identical assets or liabilities. • Level 2 - Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities, 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 assets or liabilities. • Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. At September 30, 2024, we have classified 1250 H Street, NW, 206 East 9th Street and Bridgepoint Square as held for sale in accordance with ASC 360. As a result of our current estimates of market value less estimated costs to sell, it was necessary to record impairment charges of $50.2 million which includes $16.3 million of impairment related to non-real estate assets. We determined these impairments based on third-party offer prices, which are level 2 inputs according to the fair value hierarchy established in ASC 820. We reduced the aggregate carrying values of these properties from $136.9 million to their estimated fair value less estimated costs to sell of $86.7 million. We evaluated each of our properties and determined there were no additional valuation adjustments necessary at September 30, 2024. Financial Instruments Our financial instruments include our cash and cash equivalents. At September 30, 2024 and December 31, 2023, the fair value of these financial instruments was not different from their carrying values.

Earnings Per Common Share

Earnings Per Common Share	9 Months Ended
Earnings Per Common Share	Sep. 30, 2024
Earnings Per Share [Abstract]
Earnings Per Common Share	Earnings Per Common Share The following table sets forth the computation of basic and diluted earnings per share (amounts in thousands except per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Numerator for earnings per common share - basic: Net (loss) income $ (26,227) $ 26,232 $ 23,417 $ 64,819 Net loss (income) attributable to noncontrolling interest 38 (86) (51) (204) Preferred distributions (1,997) (1,997) (5,991) (5,991) Numerator for net (loss) income per share - basic $ (28,186) $ 24,149 $ 17,375 $ 58,624 Numerator for earnings per common share - diluted: Net (loss) income $ (26,227) $ 26,232 $ 23,417 $ 64,819 Net loss (income) attributable to noncontrolling interest 38 (86) (51) (204) Preferred distributions (1,997) (1,997) (5,991) (5,991) Numerator for net (loss) income per share - diluted $ (28,186) $ 24,149 $ 17,375 $ 58,624 Denominator for earnings per common share - basic and diluted: Weighted average number of common shares outstanding - basic (1) 107,456 108,931 107,363 109,494 RSUs (2) — 1,176 921 1,299 LTIP Units (3) — 110 107 123 Weighted average number of common shares outstanding - diluted 107,456 110,217 108,391 110,916 Net (loss) income per common share attributable to Equity Commonwealth common shareholders: Basic $ (0.26) $ 0.22 $ 0.16 $ 0.54 Diluted $ (0.26) $ 0.22 $ 0.16 $ 0.53 Anti-dilutive securities (4) : Effect of Series D preferred shares; 6.50% cumulative convertible 4,032 4,032 4,032 4,032 Effect of RSUs (2) 640 — — — Effect of LTIP Units (3) 101 — — — Effect of OP Units and time-based LTIP Units (5) 154 361 180 348 (1) The three months ended September 30, 2024 and 2023, include 128 and 131 weighted-average, unvested, earned RSUs, respectively, and the nine months ended September 30, 2024 and 2023, include 129 and 125 weighted-average, unvested, earned RSUs, respectively. (2) Represents the weighted-average number of common shares that would have been issued if the quarter-end was the measurement date for unvested, unearned RSUs. (3) Represents the weighted-average dilutive shares issuable from market-based LTIP Units if the quarter-end was the measurement date for the periods shown. (4) These securities are excluded from the diluted earnings per share calculation for one or more of the periods presented because including them results in anti-dilution. (5) Beneficial interests in the Operating Trust.

Segment Information

Segment Information	9 Months Ended
Segment Information	Sep. 30, 2024
Segment Reporting [Abstract]
Segment Information	Segment InformationOur primary business is the ownership and operation of office properties, and we currently have one reportable segment. One hundred percent of our revenues for the nine months ended September 30, 2024 were from office properties.

Related Person Transactions

Related Person Transactions	9 Months Ended
Related Person Transactions	Sep. 30, 2024
Related Party Transactions [Abstract]
Related Person Transactions	Related Person Transactions The following discussion includes a description of our related person transactions for the nine months ended September 30, 2024 and 2023. We lease office space for our corporate headquarters from Two North Riverside Plaza Joint Venture Limited Partnership, an entity associated with Equity Group Investments (EGI), a private entrepreneurial investment firm founded by Sam Zell, our former Chairman who passed away on May 18, 2023. Messrs. Helfand and Weinberg continue to be advisors to EGI and certain other members of our team are expected to continue to have limited involvement in its activities. In December 2022, we entered into a third amendment to our July 20, 2015 lease with Two North Riverside Plaza Joint Venture Limited Partnership to occupy office space on the twentieth and twenty-first floors of Two North Riverside Plaza in Chicago, Illinois. The amendment extended the lease term for one year, through December 31, 2023, with no renewal options, for a lease payment of $0.4 million per year. In August 2023, we entered into a fourth amendment to the lease extending the lease term for one year, through December 31, 2024, with no renewal options and contracting square feet to the existing space on the twentieth floor, for a lease payment of $0.4 million per year. In April 2024, we entered into a fifth amendment to the lease extending the lease term for two additional years, through December 31, 2026, with no renewal options (as amended by the first through fifth lease amendments, the Two North Office Lease), for a lease payment of $0.4 million per year. The Two North Office Lease allows EQC to terminate the lease early for a termination fee equal to three-months’ base rent. During the three months ended September 30, 2024 and 2023, we recognized expenses of $0.1 million and $0.1 million, respectively, and during the nine months ended September 30, 2024 and 2023, we recognized expenses of $0.3 million and $0.3 million, respectively, pursuant to the Two North Office Lease. As of September 30, 2024 and December 31, 2023, we did not have any amounts due to Two North Riverside Plaza Joint Venture Limited Partnership pursuant to the Two North Office Lease.

Subsequent Events

Subsequent Events	9 Months Ended
Subsequent Events	Sep. 30, 2024
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Preferred Share Distribution On October 16, 2024, our Board of Trustees declared a dividend of $0.40625 per series D preferred share, which will be paid on November 15, 2024 to shareholders of record on October 31, 2024.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (26,189)	$ 26,146	$ 23,366	$ 64,615

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Sep. 30, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2024
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements of EQC have been prepared without audit. Certain information and footnote disclosures required by U.S. generally accepted accounting principles, or GAAP, for complete financial statements have been condensed or omitted. We believe the disclosures made are appropriate. The accompanying condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes contained in our Annual Report on Form 10-K, or our Annual Report, for the year ended December 31, 2023. Capitalized terms used, but not defined in this Quarterly Report, have the same meanings as in our Annual Report. In the opinion of our management, all adjustments, which include only normal recurring adjustments considered necessary for a fair presentation, have been included. All intercompany transactions and balances with or among our subsidiaries have been eliminated. Operating results for interim periods are not necessarily indicative of the results that may be expected for the full year. The preparation of financial statements in conformity with GAAP requires us to make estimates and assumptions that affect reported amounts. Actual results could differ from those estimates. Significant estimates in the condensed consolidated financial statements include the assessment of the collectability of rental revenue, purchase price allocations, useful lives of fixed assets and impairment of real estate and intangible assets. Dollar amounts presented may be approximate. Share amounts are presented in whole numbers, except where noted.
New Accounting Pronouncements	New Accounting Pronouncements In November 2023, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, which improves the disclosures about a public entity's reportable segments and addresses requests from investors for additional, more detailed information about a reportable segment's expenses. This update is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. We do not expect the adoption of ASU 2023-07 to have a material impact on our consolidated financial statements. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which enhances the transparency and decision usefulness of income tax disclosures. This update is effective for annual periods beginning after December 15, 2024. Early adoption is permitted for annual financial statements that have not yet been issued or made available for issuance. We do not expect the adoption of ASU 2023-09 to have a material impact on our consolidated financial statements.
Properties Held for Sale	Properties Held for Sale Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. A three-level valuation hierarchy exists for disclosures of fair value measurements based upon the transparency of inputs to the valuation of an asset or liability as of the measurement date. A financial instrument's categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. See Note 2 to the financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2023 for additional information. The three levels are defined below: • Level 1 - Quoted prices in active markets for identical assets or liabilities. • Level 2 - Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities, 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 assets or liabilities. • Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Real Estate Properties (Tables)

Real Estate Properties (Tables)	9 Months Ended
Real Estate Properties (Tables)	Sep. 30, 2024
Real Estate [Abstract]
Schedule of Real Estate Properties	As of September 30, 2024, we classified the following properties as held for sale: Asset Number of Properties Number of Buildings Square 1250 H Street, NW 1 1 196,490 206 East 9th Street (Capitol Tower) 1 1 175,510 Bridgepoint Square 1 5 440,007 3 7 812,007
Summary of Properties Held-for-sale	Summarized balance sheet information for the properties classified as held for sale is as follows (in thousands): September 30, 2024 Real estate properties $ 86,707 Other assets, net 96 Properties held for sale $ 86,803 Accounts payable and accrued expenses $ 4,755 Rent collected in advance 1,445 Liabilities related to properties held for sale $ 6,200
Schedule of Rental Revenue	Rental revenue consists of the following (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Lease payments $ 8,470 $ 9,115 $ 25,908 $ 26,878 Variable lease payments 4,312 4,813 13,583 14,634 Rental revenue $ 12,782 $ 13,928 $ 39,491 $ 41,512

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	9 Months Ended
Shareholders' Equity (Tables)	Sep. 30, 2024
Stockholders' Equity Note [Abstract]
Schedule of Declared Distributions	In 2024, our Board of Trustees declared distributions on our series D preferred shares to date as follows: Declaration Date Record Date Payment Date Series D Dividend Per Share January 16, 2024 January 31, 2024 February 15, 2024 $ 0.40625 April 16, 2024 April 30, 2024 May 15, 2024 $ 0.40625 July 16, 2024 July 31, 2024 August 15, 2024 $ 0.40625 October 16, 2024 October 31, 2024 November 15, 2024 $ 0.40625

Noncontrolling Interest (Tables

Noncontrolling Interest (Tables)	9 Months Ended
Noncontrolling Interest (Tables)	Sep. 30, 2024
Noncontrolling Interest [Abstract]
Schedule of Issued and Outstanding Common Shares	The following table presents the changes in Equity Commonwealth’s issued and outstanding common shares and units for the nine months ended September 30, 2024: Common Shares OP Units and LTIP Units Total Outstanding at January 1, 2024 106,847,438 226,018 107,073,456 Repurchase and surrender of shares (161,837) — (161,837) OP Unit redemption 77,793 (77,793) — Share-based compensation grants and vesting, net of forfeitures 564,297 6,218 570,515 Outstanding at September 30, 2024 107,327,691 154,443 107,482,134 Noncontrolling ownership interest in the Operating Trust 0.14 %
Schedule of Issued and Outstanding Units	The following table presents the changes in Equity Commonwealth’s issued and outstanding common shares and units for the nine months ended September 30, 2024: Common Shares OP Units and LTIP Units Total Outstanding at January 1, 2024 106,847,438 226,018 107,073,456 Repurchase and surrender of shares (161,837) — (161,837) OP Unit redemption 77,793 (77,793) — Share-based compensation grants and vesting, net of forfeitures 564,297 6,218 570,515 Outstanding at September 30, 2024 107,327,691 154,443 107,482,134 Noncontrolling ownership interest in the Operating Trust 0.14 %

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
Income Taxes (Tables)	Sep. 30, 2024
Income Tax Disclosure [Abstract]
Schedule of Provision for Income Taxes	Our provision for income taxes consists of the following (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Current: State and local $ (22) $ (30) $ (486) $ (90) Federal — — — (1,816) Income tax expense $ (22) $ (30) $ (486) $ (1,906) Federal income tax expense in the 2023 period relates to federal income taxes at our taxable REIT subsidiary.

Share-Based Compensation (Table

Share-Based Compensation (Tables)	9 Months Ended
Share-Based Compensation (Tables)	Sep. 30, 2024
Share-Based Payment Arrangement [Abstract]
Summary of Assumptions and Fair Values for RSUs and Market-based LTIP Units Granted in the Period	The assumptions and fair value for the RSUs granted during the nine months ended September 30, 2024 are included in the following table on a per share basis. 2024 Fair value of market-based awards granted $ 27.08 Expected term (years) 4 Expected volatility 15.46 % Risk-free rate 4.06 %

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	9 Months Ended
Earnings Per Common Share (Tables)	Sep. 30, 2024
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted Earnings Per Share	The following table sets forth the computation of basic and diluted earnings per share (amounts in thousands except per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Numerator for earnings per common share - basic: Net (loss) income $ (26,227) $ 26,232 $ 23,417 $ 64,819 Net loss (income) attributable to noncontrolling interest 38 (86) (51) (204) Preferred distributions (1,997) (1,997) (5,991) (5,991) Numerator for net (loss) income per share - basic $ (28,186) $ 24,149 $ 17,375 $ 58,624 Numerator for earnings per common share - diluted: Net (loss) income $ (26,227) $ 26,232 $ 23,417 $ 64,819 Net loss (income) attributable to noncontrolling interest 38 (86) (51) (204) Preferred distributions (1,997) (1,997) (5,991) (5,991) Numerator for net (loss) income per share - diluted $ (28,186) $ 24,149 $ 17,375 $ 58,624 Denominator for earnings per common share - basic and diluted: Weighted average number of common shares outstanding - basic (1) 107,456 108,931 107,363 109,494 RSUs (2) — 1,176 921 1,299 LTIP Units (3) — 110 107 123 Weighted average number of common shares outstanding - diluted 107,456 110,217 108,391 110,916 Net (loss) income per common share attributable to Equity Commonwealth common shareholders: Basic $ (0.26) $ 0.22 $ 0.16 $ 0.54 Diluted $ (0.26) $ 0.22 $ 0.16 $ 0.53 Anti-dilutive securities (4) : Effect of Series D preferred shares; 6.50% cumulative convertible 4,032 4,032 4,032 4,032 Effect of RSUs (2) 640 — — — Effect of LTIP Units (3) 101 — — — Effect of OP Units and time-based LTIP Units (5) 154 361 180 348 (1) The three months ended September 30, 2024 and 2023, include 128 and 131 weighted-average, unvested, earned RSUs, respectively, and the nine months ended September 30, 2024 and 2023, include 129 and 125 weighted-average, unvested, earned RSUs, respectively. (2) Represents the weighted-average number of common shares that would have been issued if the quarter-end was the measurement date for unvested, unearned RSUs. (3) Represents the weighted-average dilutive shares issuable from market-based LTIP Units if the quarter-end was the measurement date for the periods shown. (4) These securities are excluded from the diluted earnings per share calculation for one or more of the periods presented because including them results in anti-dilution. (5) Beneficial interests in the Operating Trust.

Business (Details)

Business (Details) $ in Thousands, ft² in Millions	Sep. 30, 2024 USD ($) ft² property building	Dec. 31, 2023 USD ($)
Noncontrolling Interest [Line Items]
Cash and cash equivalents \| $	$ 2,225,150	$ 2,160,535
Consolidated Properties
Noncontrolling Interest [Line Items]
Number of Properties \| property	4
Number of Buildings \| building	8
Square footage (in sqft) \| ft²	1.5
Operating Trust
Noncontrolling Interest [Line Items]
Noncontrolling interest, ownership percentage by parent	99.86%

Real Estate Properties - Narrat

Real Estate Properties - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Real Estate [Abstract]
Real estate improvements	$ 11.4	$ 5.5

Real Estate Properties - Summar

Real Estate Properties - Summary of Properties Held-For-Sale (Details) - Held-for-sale	Sep. 30, 2024 ft² building
Real Estate Properties [Line Items]
Number of Properties	3
Number of Buildings	7
Square footage (in sqft) \| ft²	812,007
1250 H Street, NW
Real Estate Properties [Line Items]
Number of Properties	1
Number of Buildings	1
Square footage (in sqft) \| ft²	196,490
206 East 9th Street (Capitol Tower)
Real Estate Properties [Line Items]
Number of Properties	1
Number of Buildings	1
Square footage (in sqft) \| ft²	175,510
Bridgepoint Square
Real Estate Properties [Line Items]
Number of Properties	1
Number of Buildings	5
Square footage (in sqft) \| ft²	440,007

Real Estate Properties - Summ_2

Real Estate Properties - Summary of Properties Held-for-sale (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Liabilities related to properties held for sale	$ 6,200	$ 0
Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Real estate properties	86,707
Other assets, net	96
Properties held for sale	86,803
Accounts payable and accrued expenses	4,755
Rent collected in advance	1,445
Liabilities related to properties held for sale	$ 6,200

Real Estate Properties - Rental

Real Estate Properties - Rental Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Real Estate [Abstract]
Lease payments	$ 8,470	$ 9,115	$ 25,908	$ 26,878
Variable lease payments	4,312	4,813	13,583	14,634
Rental revenue	$ 12,782	$ 13,928	$ 39,491	$ 41,512

Shareholders' Equity - Narrativ

Shareholders' Equity - Narrative (Details) - USD ($)	1 Months Ended	9 Months Ended
Shareholders' Equity - Narrative (Details) - USD ($)	Feb. 29, 2024	Sep. 30, 2024	Sep. 30, 2023	Jun. 18, 2024
Class of Stock [Line Items]
Distributions to common shareholders/unitholders	$ 2,000,000	$ 2,036,000	$ 468,232,000
Common Shares
Class of Stock [Line Items]
Shares repurchased (in shares)		0
Stock repurchase program, remaining authorized repurchase amount		$ 150,000,000
Stock repurchase program, authorized amount				$ 150,000,000
Surrender of shares for tax withholding (in shares)		161,837	134,193

Shareholders' Equity - Schedule

Shareholders' Equity - Schedule of Declared Distributions (Details) - $ / shares	3 Months Ended
	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024
Subsequent Event [Line Items]
Dividend paid (in dollars per share)		$ 0.40625	$ 0.40625	$ 0.40625
Dividend declared (in dollars per share)		$ 0.40625	$ 0.40625	$ 0.40625
Subsequent event
Subsequent Event [Line Items]
Dividend paid (in dollars per share)	$ 0.40625
Dividend declared (in dollars per share)	$ 0.40625

Noncontrolling Interest - Narra

Noncontrolling Interest - Narrative (Details)	3 Months Ended	9 Months Ended
Noncontrolling Interest - Narrative (Details)	Sep. 30, 2024	Sep. 30, 2024
Noncontrolling Interest [Line Items]
Common stock, conversion term (in months)		6 months
Common stock, conversion basis		1
Operating Trust
Noncontrolling Interest [Line Items]
Noncontrolling interest, weighted average ownership percentage by parent	99.86%	99.83%

Noncontrolling Interest - Commo

Noncontrolling Interest - Common Shares and Units Activity (Details)	9 Months Ended
	Sep. 30, 2024 shares
Equity Commonwealth
Increase (Decrease) in Stockholders' Equity
Noncontrolling ownership interest in the Operating Trust	0.14%
Common Stock, OP Units, and LTIP Units
Increase (Decrease) in Stockholders' Equity
Balance as of beginning of period (in shares)	107,073,456
Repurchase and surrender of shares (in shares)	(161,837)
OP unit redemption (in shares)	0
Share-based compensation grants and vesting, net of forfeitures (in shares)	570,515
Balance as of end of period (in shares)	107,482,134
Common Shares
Increase (Decrease) in Stockholders' Equity
Balance as of beginning of period (in shares)	106,847,438
Repurchase and surrender of shares (in shares)	(161,837)
OP unit redemption (in shares)	77,793
Share-based compensation grants and vesting, net of forfeitures (in shares)	564,297
Balance as of end of period (in shares)	107,327,691
OP Units and LTIP Units \| Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity
Balance as of beginning of period (in shares)	226,018
Repurchase and surrender of shares (in shares)	0
OP unit redemption (in shares)	(77,793)
Share-based compensation grants and vesting, net of forfeitures (in shares)	6,218
Balance as of end of period (in shares)	154,443

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Current:
State and local	$ (22)	$ (30)	$ (486)	$ (90)
Federal	0	0	0	(1,816)
Income tax expense	$ (22)	$ (30)	$ (486)	$ (1,906)

Share-Based Compensation - Narr

Share-Based Compensation - Narrative (Details) $ / shares in Units, $ in Millions					3 Months Ended		9 Months Ended
	Jun. 18, 2024 USD ($) trustee $ / shares shares	Jan. 29, 2024 $ / shares shares	Jun. 13, 2023 USD ($) trustee $ / shares shares	Jan. 26, 2023 $ / shares shares	Sep. 30, 2024 USD ($) shares	Sep. 30, 2023 USD ($) shares	Sep. 30, 2024 USD ($) tranche $ / shares shares	Sep. 30, 2023 USD ($) shares	Dec. 31, 2023 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of trustees in board of trustees \| trustee	6		6
Share based compensation amount \| $	$ 0.1		$ 0.1
Common stock issued (in shares)					107,327,691		107,327,691		106,847,438
Compensation expense, accelerated vesting due to a staffing reduction \| $					$ 0.1	$ 0	$ 0.1	$ 5.2
Common shares available for issuance (in shares)					1,406,557		1,406,557
General and Administrative Expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $					$ 2.8	$ 2.5	$ 8	$ 13.5
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)							3 years
Number of tranches \| tranche							2
Share-based compensation arrangement (in shares)							391,061	274,739
Common stock issued (in shares)					391,061	274,739	391,061	274,739
Granted shares value (in dollars per share) \| $ / shares							$ 27.08
RSUs \| Vesting in three years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percent							50%
RSUs \| Vesting in four years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)							1 year
Vesting percent							50%
RSUs at target
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of equity awards granted (in shares)		288,596		269,609
RSUs at maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of equity awards granted (in shares)		719,326		672,000
LTIP Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Conversion basis					1		1
Restricted Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of equity awards granted (in shares)	31,090	142,146	28,865	132,794
Granted shares value (in dollars per share) \| $ / shares		$ 19.36
Restricted Shares and Time-Based LTIP Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	1 year
Granted shares value (in dollars per share) \| $ / shares				$ 25.61
Exercise price (in dollars per share) \| $ / shares	$ 19.30		$ 20.79
Estimated future compensation expense for unvested shares \| $					$ 5.3		$ 5.3
Weighted average period over which compensation expense will be recorded (in years)							2 years 4 months 24 days
Restricted Shares and Time-Based LTIP Units \| Independent Trustee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of equity awards granted (in shares)	6,218		5,773
RSUs and Market-Based LTIP Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted shares value (in dollars per share) \| $ / shares				$ 36.51
Estimated future compensation expense for unvested shares \| $					$ 12		$ 12
Weighted average period over which compensation expense will be recorded (in years)							2 years 3 months 18 days
Time-based LTIP Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of equity awards granted (in shares)	6,218		5,773

Share-Based Compensation - Summ

Share-Based Compensation - Summary of Assumptions and Fair Values for RSUs and Market-based LTIP Units Granted in the Period (Details) - RSUs	9 Months Ended
	Sep. 30, 2024 $ / shares
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Fair value of market-based awards granted	$ 27.08
Expected term (years)	4 years
Expected volatility	15.46%
Risk-free rate	4.06%

Fair Value of Assets and Liab_2

Fair Value of Assets and Liabilities - Narrative (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Fair value of assets and liabilities
Impairment		$ 50,226	$ 0	$ 50,226	$ 0
Real estate properties, net	$ 111,298	111,298		111,298		$ 231,352
Held-for-sale
Fair value of assets and liabilities
Real estate properties, net	136,900	136,900		136,900
Selling costs	86,700	$ 86,700		$ 86,700
Significant Other Observable Inputs (Level 2) \| Held-for-sale
Fair value of assets and liabilities
Impairment	50,200
Impairment of non-real estate assets	$ 16,300

Earnings Per Common Share (Deta

Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Numerator for earnings per common share - basic:
Net income	$ (26,227)	$ 26,232	$ 23,417	$ 64,819
Net loss (income) attributable to noncontrolling interest	38	(86)	(51)	(204)
Preferred distributions	(1,997)	(1,997)	(5,991)	(5,991)
Net (loss) income attributable to Equity Commonwealth common shareholders	(28,186)	24,149	17,375	58,624
Numerator for earnings per common share - diluted:
Net income	(26,227)	26,232	23,417	64,819
Net loss (income) attributable to noncontrolling interest	38	(86)	(51)	(204)
Preferred distributions	(1,997)	(1,997)	(5,991)	(5,991)
Numerator for net (loss) income per share - diluted	$ (28,186)	$ 24,149	$ 17,375	$ 58,624
Denominator for earnings per common share - basic and diluted:
Weighted average number of common shares outstanding — basic (in shares)	107,456	108,931	107,363	109,494
Weighted average number of common shares outstanding — diluted (in shares)	107,456	110,217	108,391	110,916
Net (loss) income per common share attributable to Equity Commonwealth common shareholders:
Basic (in dollars per share)	$ (0.26)	$ 0.22	$ 0.16	$ 0.54
Diluted (in dollars per share)	$ (0.26)	$ 0.22	$ 0.16	$ 0.53
Anti-dilutive securities:
Preferred shares, dividend percentage			6.50%		6.50%
Weighted average number of shares, restricted stock units, unvested (in shares)	128	131	129	125
6.50% Series D Cumulative Convertible Preferred Shares of Beneficial Interest
Anti-dilutive securities:
Effect of anti-dilutive securities (in shares)	4,032	4,032	4,032	4,032
RSUs
Anti-dilutive securities:
Effect of anti-dilutive securities (in shares)	640	0	0	0
LTIP Units
Anti-dilutive securities:
Effect of anti-dilutive securities (in shares)	101	0	0	0
OP Units and LTIP Units
Anti-dilutive securities:
Effect of anti-dilutive securities (in shares)	154	361	180	348
RSUs
Denominator for earnings per common share - basic and diluted:
Weighted average number of common shares outstanding, dilutive adjustment (in shares)	0	1,176	921	1,299
LTIP Units
Denominator for earnings per common share - basic and diluted:
Weighted average number of common shares outstanding, dilutive adjustment (in shares)	0	110	107	123

Segment Information (Details)

Segment Information (Details)	9 Months Ended
Segment Information (Details)	Sep. 30, 2024 segment
Segment Reporting [Abstract]
Number of reportable segments	1
Office Building \| Total rents \| Product Concentration Risk
Segment Reporting Information [Line Items]
Concentration risk	100%

Related Person Transactions (De

Related Person Transactions (Details) - Two North Riverside Plaza Joint Venture Limited Partnership - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Apr. 30, 2024	Dec. 31, 2023	Aug. 31, 2023
Related Party Transaction [Line Items]
Lease payment					$ 0.4	$ 0.4	$ 0.4
Operating lease, expense	$ 0.1	$ 0.1	$ 0.3	$ 0.3

Subsequent Events (Details)

Subsequent Events (Details) - $ / shares	3 Months Ended
Subsequent Events (Details) - $ / shares	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024
Subsequent Event [Line Items]
Dividend declared (in dollars per share)		$ 0.40625	$ 0.40625	$ 0.40625
Dividend paid (in dollars per share)		$ 0.40625	$ 0.40625	$ 0.40625
Subsequent event
Subsequent Event [Line Items]
Dividend declared (in dollars per share)	$ 0.40625
Dividend paid (in dollars per share)	$ 0.40625