AECOM (ACM) 10-K17 Nov 212021 FY Annual reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
Document and Entity Information - USD ($) $ in Billions	Sep. 30, 2021	Nov. 11, 2021	Apr. 02, 2021
Document and Entity Information
Document Type	10-K
Document Annual Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	0-52423
Entity Registrant Name	AECOM
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	61-1088522
Entity Address, Address Line One	13355 Noel Road
Entity Address, City or Town	Dallas
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	75240
City Area Code	972
Local Phone Number	788-1000
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
Title of 12(b) Security	Common Stock
Trading Symbol	ACM
Security Exchange Name	NYSE
Entity Common Stock, Shares Outstanding		142,202,244
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Public Float			$ 9.4
Current Fiscal Year End Date	--09-30
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Central Index Key	0000868857
ICFR Auditor Attestation Flag	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020
CURRENT ASSETS:
Cash and cash equivalents	$ 1,120,790	$ 1,599,688
Cash in consolidated joint ventures	108,406	108,644
Total cash and cash equivalents	1,229,196	1,708,332
Accounts receivable-net	2,619,491	2,920,730
Contract assets	1,369,031	1,611,525
Prepaid expenses and other current assets	739,044	691,707
Current assets held for sale	139,426	562,435
Income taxes receivable	77,355	35,637
TOTAL CURRENT ASSETS	6,173,543	7,530,366
PROPERTY AND EQUIPMENT-NET	398,876	381,672
DEFERRED TAX ASSETS-NET	360,260	361,675
INVESTMENTS IN UNCONSOLIDATED JOINT VENTURES	328,906	297,595
GOODWILL	3,502,499	3,484,221
INTANGIBLE ASSETS-NET	54,867	76,917
OTHER NON-CURRENT ASSETS	307,927	160,036
OPERATING LEASE RIGHT-OF-USE ASSETS	607,076	652,115
NON-CURRENT ASSETS HELD FOR SALE		54,354
TOTAL ASSETS	11,733,954	12,998,951
CURRENT LIABILITIES:
Short-term debt	4,369	223
Accounts payable	2,090,479	2,358,228
Accrued expenses and other current liabilities	2,174,201	2,249,704
Income taxes payable	50,511	47,103
Contract liabilities	1,058,643	996,922
Current liabilities held for sale	94,043	417,623
Current portion of long-term debt	49,469	20,651
TOTAL CURRENT LIABILITIES	5,521,715	6,090,454
OTHER LONG-TERM LIABILITIES	145,444	162,784
OPERATING LEASE LIABILITIES, NON-CURRENT	679,059	745,287
LONG-TERM LIABILITIES HELD FOR SALE	11,095	79,254
DEFERRED TAX LIABILITY-NET	5,420	3,491
PENSION BENEFIT OBLIGATIONS	383,904	463,001
LONG-TERM DEBT	2,157,740	2,041,136
TOTAL LIABILITIES	8,904,377	9,585,407
COMMITMENTS AND CONTINGENCIES (Note 18)
AECOM STOCKHOLDERS' EQUITY:
Common stock-authorized, 300,000,000 shares of $0.01 par value as of September 30, 2021 and 2020; issued and outstanding 143,168,815 and 157,044,687 shares as of September 30, 2021 and 2020, respectively	1,432	1,570
Additional paid-in capital	4,115,541	4,035,414
Accumulated other comprehensive loss	(900,377)	(918,674)
(Accumulated deficits) / Retained earnings	(504,126)	174,248
TOTAL AECOM STOCKHOLDERS' EQUITY	2,712,470	3,292,558
Noncontrolling interests	117,107	120,986
TOTAL STOCKHOLDERS' EQUITY	2,829,577	3,413,544
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 11,733,954	$ 12,998,951

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2021	Sep. 30, 2020
Consolidated Balance Sheets
Common stock, authorized shares	300,000,000	300,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, issued shares	143,168,815	157,044,687
Common stock, outstanding shares	143,168,815	157,044,687

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Consolidated Statements of Operations
Revenue	$ 13,340,852	$ 13,239,976	$ 13,642,455
Cost of revenue	12,542,431	12,530,416	13,030,800
Gross profit	798,421	709,560	611,655
Equity in earnings of joint ventures	35,044	48,781	49,320
General and administrative expenses	(155,072)	(188,535)	(148,123)
Restructuring costs	(48,840)	(188,345)	(95,446)
Gain on disposal activities			3,590
Impairment of long-lived assets			(24,900)
Income from operations	629,553	381,461	396,096
Other income	17,603	11,056	14,556
Interest expense	(238,352)	(159,914)	(161,482)
Income from continuing operations before taxes	408,804	232,603	249,170
Income tax expense for continuing operations	89,011	45,753	13,498
Net income from continuing operations	319,793	186,850	235,672
Net loss from discontinued operations	(116,813)	(340,591)	(419,662)
Net income (loss)	202,980	(153,741)	(183,990)
Net income attributable to noncontrolling interests from continuing operations	(25,109)	(16,398)	(24,710)
Net income attributable to noncontrolling interests from discontinued operations	(4,686)	(16,231)	(52,350)
Net income attributable to noncontrolling interests	(29,795)	(32,629)	(77,060)
Net income attributable to AECOM from continuing operations	294,684	170,452	210,962
Net loss attributable to AECOM from discontinued operations	(121,499)	(356,822)	(472,012)
Net income (loss) attributable to AECOM	$ 173,185	$ (186,370)	$ (261,050)
Net income (loss) attributable to AECOM per share:
Basic continuing operations per share	$ 2	$ 1.07	$ 1.34
Basic discontinued operations per share	(0.82)	(2.24)	(3)
Basic earnings per share	1.18	(1.17)	(1.66)
Diluted continuing operations per share	1.97	1.06	1.32
Diluted discontinued operations per share	(0.81)	(2.22)	(2.95)
Diluted earnings per share	$ 1.16	$ (1.16)	$ (1.63)
Weighted average shares outstanding:
Basic	147,279	159,005	157,044
Diluted	149,676	161,292	159,684

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Consolidated Statements of Comprehensive Income (Loss)
Net income (loss)	$ 202,980	$ (153,741)	$ (183,990)
Other comprehensive loss, net of tax:
Net unrealized gain (loss) on derivatives, net of tax	4,541	4,094	(13,972)
Foreign currency translation adjustments	(12,601)	(18,206)	(46,628)
Pension adjustments, net of tax	26,591	(40,051)	(100,367)
Other comprehensive income (loss), net of tax	18,531	(54,163)	(160,967)
Comprehensive income (loss), net of tax	221,511	(207,904)	(344,957)
Noncontrolling interests in comprehensive income of consolidated subsidiaries, net of tax	(30,029)	(32,943)	(76,960)
Comprehensive income (loss) attributable to AECOM, net of tax	$ 191,482	$ (240,847)	$ (421,917)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Retained Earnings (Deficits)Cumulative effect of accounting standard adoption	Retained Earnings (Deficits)	Total AECOM Stockholders' EquityCumulative effect of accounting standard adoption	Total AECOM Stockholders' Equity	Non-Controlling Interests	Cumulative effect of accounting standard adoption	Total
BALANCE at Sep. 30, 2018	$ 1,570	$ 3,846,392	$ (703,330)		$ 948,148		$ 4,092,780	$ 185,594		$ 4,278,374
Increase (Decrease) in Stockholders' Equity
Net income (loss)					(261,050)		(261,050)	77,060		(183,990)
Other comprehensive loss			(160,867)				(160,867)	(100)		(160,967)
Issuance of stock	44	66,517					66,561			66,561
Repurchases of stock	(39)	(23,071)			(75,098)		(98,208)			(98,208)
Stock based compensation		63,812					63,812			63,812
Other transactions with noncontrolling interests								16,208		16,208
Contributions from noncontrolling interests								5,069		5,069
Distributions to noncontrolling interests								(75,057)		(75,057)
BALANCE at Sep. 30, 2019	1,575	3,953,650	(864,197)	$ (12,452)	599,548	$ (12,452)	3,690,576	208,774	$ (12,452)	3,899,350
Increase (Decrease) in Stockholders' Equity
Net income (loss)					(186,370)		(186,370)	32,629		(153,741)
Other comprehensive loss			(54,477)				(54,477)	314		(54,163)
Issuance of stock	43	63,297					63,340			63,340
Repurchases of stock	(48)	(35,762)			(151,143)		(186,953)			(186,953)
Stock based compensation		54,229					54,229			54,229
Disposal of noncontrolling interest of business sold								(60,089)		(60,089)
Contributions from noncontrolling interests								9,917		9,917
Distributions to noncontrolling interests								(70,559)		(70,559)
BALANCE at Sep. 30, 2020	1,570	4,035,414	(918,674)	(87,787)	174,248	(87,787)	3,292,558	120,986	(87,787)	3,413,544
Increase (Decrease) in Stockholders' Equity
Net income (loss)					173,185		173,185	29,795		202,980
Other comprehensive loss			18,297				18,297	234		18,531
Issuance of stock	25	58,733					58,758			58,758
Repurchases of stock	(163)	(23,348)			(843,580)		(867,091)			(867,091)
Stock based compensation		44,742					44,742			44,742
Disposal of noncontrolling interest of business sold								(24,039)		(24,039)
Other transactions with noncontrolling interests								405		405
Contributions from noncontrolling interests								271		271
Distributions to noncontrolling interests								(10,545)		(10,545)
BALANCE at Sep. 30, 2021	$ 1,432	$ 4,115,541	$ (900,377)	$ (7,979)	$ (504,126)	$ (7,979)	$ 2,712,470	$ 117,107	$ (7,979)	$ 2,829,577

Consolidated Statements of Cash

Consolidated Statements of Cash Flows $ in Thousands	12 Months Ended
Consolidated Statements of Cash Flows $ in Thousands	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ 202,980	$ (153,741)	$ (183,990)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	176,400	237,376	261,185
Equity in earnings of unconsolidated joint ventures	(39,104)	(23,279)	(80,990)
Distribution of earnings from unconsolidated joint ventures	46,358	90,158	65,954
Non-cash stock compensation	44,742	54,229	63,812
Prepayment premium on redemption of unsecured senior notes	117,500	16,986
Impairment of long-lived assets, including goodwill	105,194	336,472	615,400
Loss on disposal activities			10,381
Loss (gain) on sale of discontinued operations	52,532	(161,900)
Foreign currency translation	(42,728)	(31,919)	(19,099)
Deferred income tax (benefit) expense	(48,265)	11,130	(98,015)
Other	16,063	32,028	5,899
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable and contract assets	533,006	(136,955)	(316,487)
Prepaid expenses and other assets	(100,526)	(31,815)	(16,576)
Accounts payable	(250,142)	(192,980)	251,410
Accrued expenses and other current liabilities	(84,073)	118,441	259,572
Contract liabilities	103,999	128,312	7,559
Other long-term liabilities	(129,266)	37,079	(48,399)
Net cash provided by operating activities	704,670	329,622	777,616
CASH FLOWS FROM INVESTING ACTIVITIES:
(Payment for) proceeds from sale of discontinued operations, net of cash disposed	(265,876)	2,218,866
Proceeds from disposal of businesses, net of cash disposed			46,490
Investment in unconsolidated joint ventures	(57,388)	(111,077)	(141,769)
Return of investment in unconsolidated joint ventures	8,110	28,047	22,750
Proceeds from sale of investments	15,507	12,392	12,365
Payments for purchase of investments			(3,223)
Proceeds from disposal of property and equipment	14,822	3,800	17,291
Payments for capital expenditures	(136,262)	(114,591)	(100,664)
Net cash (used in) provided by investing activities	(421,087)	2,037,437	(146,760)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from borrowings under credit agreements	3,638,916	4,452,078	7,700,774
Repayments of borrowings under credit agreements	(2,726,347)	(5,568,320)	(7,984,624)
Redemption of unsecured senior notes	(797,252)	(248,522)
Prepayment premium on redemption of unsecured senior notes	(117,500)	(16,986)
Cash paid for debt issuance costs	(11,280)	(4,228)
Proceeds from issuance of common stock	25,686	26,388	30,448
Proceeds from exercise of stock options	4,038
Payments to repurchase common stock	(867,091)	(186,953)	(98,208)
Net distributions to noncontrolling interests	(10,274)	(60,642)	(69,988)
Other financing activities	(11,429)	(20,785)	(11,681)
Net cash used in financing activities	(872,533)	(1,627,970)	(433,279)
EFFECT OF EXCHANGE RATE CHANGES ON CASH	5,493	(1,194)	(3,956)
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(583,457)	737,895	193,621
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	1,818,249	1,080,354	886,733
CASH AND CASH EQUIVALENTS AT END OF YEAR	1,234,792	1,818,249	1,080,354
LESS: CASH AND CASH EQUIVALENTS INCLUDED IN CURRENT ASSETS HELD FOR SALE	(5,596)	(109,917)	(194,715)
CASH AND CASH EQUIVALENTS OF CONTINUING OPERATIONS AT END OF YEAR	1,229,196	1,708,332	885,639
SUPPLEMENTAL CASH FLOW INFORMATION:
Interest paid	(255,679)	(201,402)	(222,263)
Net income taxes (paid) refund received	$ 114,464	$ 71,031	$ (2,500)

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
Significant Accounting Policies	Sep. 30, 2021
Significant Accounting Policies
Significant Accounting Policies	1. Significant Accounting Policies Organization Fiscal Year Use of Estimates Principles of Consolidation and Presentation Government Contract Matters Audits by the DCAA and other agencies consist of reviews of the Company’s overhead rates, operating systems and cost proposals to ensure that the Company accounted for such costs in accordance with the Cost Accounting Standards of the FAR (CAS). If the DCAA determines the Company has not accounted for such costs consistent with CAS, the DCAA may disallow these costs. There can be no assurance that audits by the DCAA or other governmental agencies will not result in material cost disallowances in the future. Cash and Cash Equivalents Allowance for Doubtful Accounts ● Client type—federal or state and local government or commercial client; ● Historical contract performance; ● Historical collection and delinquency trends; ● Client credit worthiness; and ● General economic conditions. Derivative Financial Instruments For derivative instruments that hedge the exposure to variability in expected future cash flows that are designated as cash flow hedges, the effective portion of the gain or loss on the derivative instrument is reported as a component of accumulated other comprehensive income in stockholders’ equity and reclassified into income in the same period or periods during which the hedged transaction affects earnings. The ineffective portion of the gain or loss on the derivative instrument, if any, is recognized in current income. To receive hedge accounting treatment, cash flow hedges must be highly effective in offsetting changes to expected future cash flows on hedged transactions. The net gain or loss on the effective portion of a derivative instrument that is designated as an economic hedge of the foreign currency translation exposure generated by the re-measurement of certain assets and liabilities denominated in a non-functional currency in a foreign operation is reported in the same manner as a foreign currency translation adjustment. Accordingly, any gains or losses related to these derivative instruments are recognized in current income. Derivatives that do not qualify as hedges are adjusted to fair value through current income. Fair Value of Financial Instruments The carrying amounts of cash and cash equivalents, accounts receivable and accounts payable approximate fair value because of the short maturities of these instruments. The carrying amount of the revolving credit facility approximates fair value because the interest rates are based upon variable reference rates. The Company’s fair value measurement methods may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. Although the Company believes its valuation methods are appropriate and consistent with those used by other market participants, the use of different methodologies or assumptions to determine fair value could result in a different fair value measurement at the reporting date. Property and Equipment ten three three Long-Lived Assets Goodwill and Acquired Intangible Assets The Company tests goodwill for impairment annually for each reporting unit in the fourth quarter of the fiscal year and between annual tests, if events occur or circumstances change which suggest that goodwill should be evaluated. Such events or circumstances include significant changes in legal factors and business climate, recent losses at a reporting unit, and industry trends, among other factors. A reporting unit is defined as an operating segment or one level below an operating segment. The Company’s impairment tests are performed at the operating segment level as they represent the Company’s reporting units. During the impairment test, the Company estimates the fair value of the reporting unit using income and market approaches, and compares that amount to the carrying value of that reporting unit. In the event the fair value of the reporting unit is determined to be less than the carrying value, goodwill is impaired, and an impairment loss is recognized equal to the excess, limited to the total amount of goodwill allocated to the reporting unit. See also Note 3. Pension Plans Insurance Reserves Foreign Currency Translation The Company uses foreign currency forward contracts from time to time to mitigate foreign currency risk. The Company limits exposure to foreign currency fluctuations in most of its contracts through provisions that require client payments in currencies corresponding to the currency in which costs are incurred. As a result of this natural hedge, the Company generally does not need to hedge foreign currency cash flows for contract work performed. Noncontrolling Interests Income Taxes

New Accounting Pronouncements a

New Accounting Pronouncements and Changes in Accounting	12 Months Ended
New Accounting Pronouncements and Changes in Accounting	Sep. 30, 2021
New Accounting Pronouncements and Changes in Accounting
New Accounting Pronouncements and Changes in Accounting	2. New Accounting Pronouncements and Changes in Accounting In February 2016, the Financial Accounting Standards Board (FASB) issued new accounting guidance which changes accounting requirements for leases. The new guidance requires lessees to recognize the assets and liabilities arising from all leases, including those classified as operating leases under previous accounting guidance, on the balance sheet. It also requires disclosure of key information about leasing arrangements to increase transparency and comparability among organizations. The Company adopted the new guidance beginning October 1, 2019 using the modified retrospective adoption method, which resulted in a downward adjustment to retained earnings of $87.8 million, net of tax. Detailed disclosures regarding the adoption and other required disclosures can be found in Note 11. In June 2016, the FASB issued a new credit loss standard that changes the impairment model for most financial assets and some other instruments. The new guidance replaces the “incurred loss” approach with an “expected loss” model for instruments measured at amortized cost. It also simplifies the accounting model for purchased credit-impaired debt securities and loans. The Company adopted the new guidance effective October 1, 2020 using a modified retrospective approach that resulted in an $8.0 million, net of tax, reduction to retained earnings without restating comparative periods. Additional disclosures regarding the adoption can be found in Note 4. In February 2018, the FASB issued new accounting guidance which provides entities the option to reclassify certain tax effects from other comprehensive income to retained earnings. The guidance addresses a narrow-scope financial reporting issue related to the tax effects that may become stranded in accumulated other comprehensive income as a result of the enactment of the Tax Cuts and Jobs Act (Tax Act). Under the guidance, an entity may elect to reclassify the income tax effects of the Tax Act on items within accumulated other comprehensive income to retained earnings. The Company has determined that it will not make this election. In August 2018, the FASB issued new accounting guidance aligning the capitalization of certain implementation costs incurred in a hosting arrangement that is a service contract with previously existing guidance for capitalizing costs incurred to develop internal-use software. The new guidance was effective for the Company’s fiscal year starting October 1, 2020. The adoption of this guidance did not have a material impact on the Company’s consolidated financial statements. In August 2018, the FASB issued new accounting guidance amending the disclosure requirements for fair value measurements. These improvements require more disclosure for amounts measured at fair value, and specifically unobservable inputs used in fair value measurements. The Company adopted the new guidance starting on October 1, 2020. Adoption of the new guidance did not have a significant impact on the Company’s financial reporting process. In August 2018, the FASB issued new accounting guidance for the disclosure requirements of defined benefit pension plans. The amended guidance eliminates certain disclosure requirements that were no longer considered to be cost beneficial. The Company expects to adopt the new guidance starting on October 1, 2021 and does not expect adoption of the new guidance will have a significant impact on its financial reporting process. In March 2020, the Securities and Exchange Commission (SEC) adopted final rules that amend the financial disclosure requirement for guarantors of registered debt securities in Rule 3-10 of Regulation S-X. The new rules amend and streamline the disclosures required by guarantors and issuers of guaranteed securities. Among other things, the new disclosures may be located outside the financial statements. The new rule was effective January 4, 2021, and early adoption is permitted. The Company adopted the new rule on March 31, 2020. Accordingly, the revised condensed consolidating financial information is presented outside of these consolidated financial statements.

Discontinued Operations, Goodwi

Discontinued Operations, Goodwill, and Intangible Assets	12 Months Ended
Discontinued Operations, Goodwill, and Intangible Assets	Sep. 30, 2021
Discontinued Operations, Goodwill and Intangible Assets
Discontinued Operations, Goodwill, and Intangible Assets	3. Discontinued Operations, Goodwill, and Intangible Assets During the second quarter of fiscal 2020, the Company completed the sale of its Management Services business to Maverick Purchaser Sub, LLC (Purchaser), an affiliate of American Securities LLC and Lindsay Goldberg LLC. The Company received total cash consideration of $2.28 billion inclusive of the receipt in the third quarter of fiscal 2020 of $122.0 million received in connection with a favorable working capital purchase price adjustment and contingent consideration of approximately $120 million attributable to certain claims related to prior work and engagements. As a result of the sale, the Company recognized a pre-tax gain of $161.9 million. The gain on sale was included in the net loss from discontinued operations in the Consolidated Statements of Operations in fiscal year 2020. Additionally, in the first quarter of fiscal 2020, management approved a plan to dispose via sale the Company’s self-perform at-risk construction businesses within the next year. These businesses include the Company’s civil infrastructure, power, and oil and gas construction businesses that were previously reported in the Company’s Construction Services segment. After consideration of the relevant facts, the Company concluded the assets and liabilities of its Management Services business and its self-perform at-risk construction businesses met the criteria for classification as held for sale. The Company concluded the actual and proposed disposal activities represented a strategic shift that will have a major effect on the Company’s operations and financial results and qualified for presentation as discontinued operations in accordance with FASB Accounting Standards Codification (ASC) 205-20. Accordingly, the financial results of the Management Services business and the self-perform at-risk construction businesses are presented in the Consolidated Statements of Operations as discontinued operations for all periods presented. Current and non-current assets and liabilities of these businesses not sold as of the balance sheet date are presented in the Consolidated Balance Sheets as assets and liabilities held for sale for both periods presented. Interest expense allocated to discontinued operations represents interest expenses for the discontinued operations’ finance leases and term loans, which were required to be settled upon the sale of the Management Services business. During the first quarter of fiscal 2021, the Company completed the sale of its power construction business to CriticalPoint Capital, LLC. The Company recorded an additional pre-tax loss on the sale of $17.3 million in fiscal 2021 related to payments for post-closing working capital adjustments. The Company also completed the sale of its civil infrastructure construction business to affiliates of Oroco Capital in the second quarter of fiscal 2021. During the second quarter of fiscal 2021, the Company recorded a $32.8 million loss related to the sale of its civil infrastructure construction businesses. Under the terms of the sale agreement, the Company made the required cash payments and delivered the cash and cash equivalents, including cash in consolidated joint ventures, on the balance sheet at closing. As a result, the Company recorded the net cash movement of the sale as a use of cash in the investing section of its statement of cash flows. During the second quarter of fiscal 2020, the Company identified indicators of impairment for the self-perform at-risk construction business. Specifically, the Company's forecast for its Oil and Gas business decreased significantly from the prior period due primarily to the volatility in global oil prices, which negatively impacted forecasts for future revenues and earnings. As a result, the Company assessed the Oil and Gas business for impairment and determined the fair value of the disposal group was lower than its carrying value. Fair value was estimated using Level 3 inputs, such as forecasted cash flows. Accordingly, the Company recorded impairment losses for that business' goodwill of approximately $83.6 million and intangible assets of approximately $5.7 million. These impairment losses were recorded in net loss from discontinued operations on the Consolidated Statements of Operations in fiscal year 2020. During the fourth quarter of fiscal 2020, the Company recorded a $247.2 million loss related to the remeasurement of its self-perform at-risk construction businesses to fair value less cost to sell. Fair value was estimated using Level 3 inputs, such as forecasted cash flows, and Level 2 inputs, including bid prices from potential buyers. The following table represents summarized balance sheet information of assets and liabilities held for sale (in millions): September 30, September 30, 2021 2020 Cash and cash equivalents $ 5.6 $ 109.9 Receivables and contract assets 90.3 414.3 Other 43.5 38.2 Current assets held for sale $ 139.4 $ 562.4 Property and equipment, net $ 52.9 $ 119.8 Other 18.5 181.8 Write-down of assets to fair value less cost to sell (71.4) (247.2) Non-current assets held for sale $ — $ 54.4 Accounts payable and accrued expenses $ 88.5 $ 350.4 Contract liabilities — 65.6 Other 5.5 1.6 Current liabilities held for sale $ 94.0 $ 417.6 Long-term liabilities held for sale $ 11.1 $ 79.3 The following table represents summarized income statement information of discontinued operations (in millions): Fiscal Year Ended September 30, September 30, 2021 2020 Revenue $ 771.5 $ 3,150.8 Cost of revenue 760.5 3,179.2 Gross profit (loss) 11.0 (28.4) Equity in earnings (losses) of joint ventures 4.0 (25.5) (Loss) gain on disposal activities (52.5) 161.9 Transaction costs (15.3) (43.2) Impairment of long-lived assets, including goodwill (105.2) (336.5) Loss from operations (158.0) (271.7) Other income — 1.8 Interest expense (0.5) (40.5) Loss before taxes (158.5) (310.4) Income tax (benefit) expense (41.7) 30.2 Net loss from discontinued operations $ (116.8) $ (340.6) The significant components included in the Consolidated Statement of Cash Flows for the discontinued operations are as follows (in millions): Fiscal Year Ended September 30, September 30, 2021 2020 Depreciation and amortization: Property and equipment $ — $ 4.6 Intangible assets and capitalized debt issuance costs — 26.0 Payments for capital expenditures (7.3) (19.6) The changes in the carrying value of goodwill by reportable segment for the year ended September 30, 2021 were as follows: Foreign September 30, Exchange September 30, 2020 Impact 2021 (in millions) Americas $ 2,617.1 $ 9.3 $ 2,626.4 International 867.1 9.0 876.1 Total $ 3,484.2 $ 18.3 $ 3,502.5 The gross amounts and accumulated amortization of the Company’s acquired identifiable intangible assets with finite useful lives as of September 30, 2021 and September 30, 2020, included in intangible assets—net, in the accompanying consolidated balance sheets, were as follows: September 30, 2021 September 30, 2020 Gross Accumulated Intangible Gross Accumulated Intangible Amortization Amount Amortization Assets, Net Amount Amortization Assets, Net Period (in millions) (years) Backlog and customer relationships $ 663.4 $ (608.5) $ 54.9 $ 662.8 $ (585.9) $ 76.9 1 - 11 Amortization expense of acquired intangible assets included within cost of revenue was $22.6 million and $24.1 million for the years ended September 30, 2021 and 2020, respectively. The following table presents estimated amortization expense of existing intangible assets for the succeeding years: Fiscal Year (in millions) 2022 $ 18.6 2023 18.2 2024 17.4 2025 0.7 Total $ 54.9

Revenue Recognition

Revenue Recognition	12 Months Ended
Revenue Recognition	Sep. 30, 2021
Revenue Recognition
Revenue Recognition	4. Revenue Recognition The Company follows accounting principles for recognizing revenue upon the transfer of control of promised goods or services to customers, in an amount that reflects the expected consideration received in exchange for those goods or services. The Company generally recognizes revenues over time as performance obligations are satisfied. The Company generally measures its progress to completion using an input measure of total costs incurred divided by total costs expected to be incurred. In the course of providing its services, the Company routinely subcontracts for services and incurs other direct costs on behalf of its clients. These costs are passed through to clients and, in accordance with GAAP, are included in the Company’s revenue and cost of revenue. These pass through revenues for the years ended September 30, 2021, 2020 and 2019 were $7.2 billion, $7.1 billion and $7.4 billion, respectively. Recognition of revenue and profit is dependent upon a number of factors, including the accuracy of a variety of estimates made at the balance sheet date, such as engineering progress, material quantities, the achievement of milestones, penalty provisions, labor productivity and cost estimates. Additionally, the Company is required to make estimates for the amount of consideration to be received, including bonuses, awards, incentive fees, claims, unpriced change orders, penalties, and liquidated damages. Variable consideration is included in the estimate of the transaction price only to the extent that a significant reversal would not be probable. Management continuously monitors factors that may affect the quality of its estimates, and material changes in estimates are disclosed accordingly. Costs attributable to claims are treated as costs of contract performance as incurred. The following summarizes the Company’s major contract types: Cost Reimbursable Contracts Cost reimbursable contracts include cost-plus fixed fee, cost-plus fixed rate, and time-and-materials price contracts. Under cost-plus contracts, the Company charges clients for its costs, including both direct and indirect costs, plus a negotiated fee or rate. The Company recognizes revenue based on actual direct costs incurred and the applicable fixed rate or portion of the fixed fee earned as of the balance sheet date. Under time-and-materials price contracts, the Company negotiates hourly billing rates and charges its clients based on the actual time that it expends on a project. In addition, clients reimburse the Company for materials and other direct incidental expenditures incurred in connection with its performance under the contract. The Company may apply a practical expedient to recognize revenue in the amount in which it has the right to invoice if its right to consideration is equal to the value of performance completed to date. Guaranteed Maximum Price Contracts (GMP) GMP contracts share many of the same contract provisions as cost-plus and fixed-price contracts. As with cost-plus contracts, clients are provided a disclosure of all the project costs, and a lump sum or percentage fee is separately identified. The Company provides clients with a guaranteed price for the overall project (adjusted for change orders issued by clients) and a schedule including the expected completion date. Cost overruns or costs associated with project delays in completion could generally be the Company’s responsibility. For many of the Company’s commercial or residential GMP contracts, the final price is generally not established until the Company has subcontracted a substantial percentage of the trade contracts with terms consistent with the master contract, and it has negotiated additional contractual limitations, such as waivers of consequential damages as well as aggregate caps on liabilities and liquidated damages. Revenue is recognized for GMP contracts as project costs are incurred relative to total estimated project costs. Fixed-Price Contracts Fixed price contracts include both lump-sum and fixed-unit price contracts. Under lump-sum contracts, the Company performs all the work under the contract for a specified fee. Lump-sum contracts are typically subject to price adjustments if the scope of the project changes or unforeseen conditions arise. Under fixed-unit price contracts, the Company performs a number of units of work at an agreed price per unit with the total payment under the contract determined by the actual number of units delivered. Revenue is recognized for fixed-price contracts using the input method measured on a cost-to-cost basis. The following tables present the Company’s revenues disaggregated by revenue sources: Fiscal Year Ended September 30, September 30, September 30, 2021 2020 2019 (in millions) Cost reimbursable $ 5,319.4 $ 5,734.5 $ 5,958.2 Guaranteed maximum price 4,582.7 3,896.8 3,962.6 Fixed price 3,438.8 3,608.7 3,721.7 Total revenue $ 13,340.9 $ 13,240.0 $ 13,642.5 Fiscal Year Ended September 30, September 30, September 30, 2021 2020 2019 (in millions) Americas $ 10,228.3 $ 10,138.3 $ 10,390.8 Europe, Middle East, Africa 1,588.1 1,620.3 1,752.1 Asia Pacific 1,524.5 1,481.4 1,499.6 Total revenue $ 13,340.9 $ 13,240.0 $ 13,642.5 As of September 30, 2021, the Company had allocated $18.7 billion of transaction price to unsatisfied or partially satisfied performance obligations, of which approximately 55% is expected to be satisfied within the next twelve months. Contract liabilities represent amounts billed to clients in excess of revenue recognized to date. The Company recognized revenue of $692.0 million and $592.7 million during the years ended September 30, 2021 and 2020, respectively, that was included in contract liabilities as of September 30, 2020 and 2019, respectively. The Company’s timing of revenue recognition may not be consistent with its rights to bill and collect cash from its clients. Those rights are generally dependent upon advance billing terms, milestone billings based on the completion of certain phases of work or when services are performed. The Company’s accounts receivable represent amounts billed to clients that have yet to be collected and represent an unconditional right to cash from its clients. Contract assets represent the amount of contract revenue recognized but not yet billed pursuant to contract terms or accounts billed after the balance sheet date. Contract liabilities represent billings as of the balance sheet date, as allowed under the terms of a contract, but not yet recognized as contract revenue pursuant to the Company’s revenue recognition policy. Net accounts receivable consisted of the following: Fiscal Year Ended September 30, September 30, 2021 2020 (in millions) Billed $ 2,181.1 $ 2,467.3 Contract retentions 531.2 531.3 Total accounts receivable—gross 2,712.3 2,998.6 Allowance for doubtful accounts and credit losses (92.8) (77.9) Total accounts receivable—net $ 2,619.5 $ 2,920.7 Substantially all contract assets as of September 30, 2021 and September 30, 2020 are expected to be billed and collected within twelve months, except for claims. Significant claims recorded in contract assets and other non-current assets were approximately $140 million and $170 million as of September 30, 2021 and September 30, 2020, respectively. The asset related to the Deactivation, Demolition, and Removal Project retained from the Purchaser discussed in Note 18 is presented in prepaid expense and other current assets from continuing operations in the Consolidated Balance Sheet. Contract retentions represent amounts invoiced to clients where payments have been withheld from progress payments until the contracted work has been completed and approved by the client. These retention agreements vary from project to project and could be outstanding for several months or years. On October 1, 2020, the Company adopted accounting pronouncements issued by the FASB regarding the changes to the way in which entities estimate credit losses for most financial assets, including accounts receivable and contract assets. The new guidance requires the Company to maintain an allowance for credit losses, which represent the portion of its financial assets that it does not expect to collect over their contractual life. The Company considers a broad range of information to estimate expected credit losses including the related ages of past due balances, projections of credit losses based on historical trends, and collection history and credit quality of its clients. Negative macroeconomic trends or delays in payment of outstanding receivables could result in an increase in the estimated credit losses. No single client accounted for more than 10% of the Company’s outstanding receivables at September 30, 2021 and September 30, 2020. The Company sold trade receivables to financial institutions, of which $263.6 million and $166.6 million were outstanding as of September 30, 2021 and September 30, 2020, respectively. The Company does not retain financial or legal obligations for these receivables that would result in material losses. The Company’s ongoing involvement is limited to the remittance of customer payments to the financial institutions with respect to the sold trade receivables.

Property and Equipment

Property and Equipment	12 Months Ended
Property and Equipment	Sep. 30, 2021
Property and Equipment
Property and Equipment	5. Property and Equipment Property and equipment, at cost, consists of the following: Fiscal Year Ended September 30, September 30, Useful Lives 2021 2020 (years) (in millions) Building and land $ 14.4 $ 11.5 10 - 45 Leasehold improvements 351.2 343.2 1 - 20 Computer systems and equipment 602.1 557.4 3 - 12 Furniture and fixtures 112.7 134.8 3 - 10 Total 1,080.4 1,046.9 Accumulated depreciation and amortization (681.5) (665.2) Property and equipment, net $ 398.9 $ 381.7 Depreciation expense for the fiscal years ended September 30, 2021, 2020 and 2019 were $143.6 million, $163.4 million, and $137.5 million, respectively. Depreciation is calculated using primarily the straight-line method over the estimated useful lives of the assets, or in the case of leasehold improvements and capitalized leases, the lesser of the remaining term of the lease or its estimated useful life.

Joint Ventures and Variable Int

Joint Ventures and Variable Interest Entities	12 Months Ended
Joint Ventures and Variable Interest Entities	Sep. 30, 2021
Joint Ventures and Variable Interest Entities
Joint Ventures and Variable Interest Entities	6. Joint Ventures and Variable Interest Entities The Company’s joint ventures provide architecture, engineering, program management, construction management, operations and maintenance services and invest in real estate projects. Joint ventures, the combination of two or more partners, are generally formed for a specific project. Management of the joint venture is typically controlled by a joint venture executive committee, comprised of representatives from the joint venture partners. The joint venture executive committee normally provides management oversight and controls decisions which could have a significant impact on the joint venture. Some of the Company’s joint ventures have no employees and minimal operating expenses. For these joint ventures, the Company’s employees perform work for the joint venture, which is then billed to a third-party customer by the joint venture. These joint ventures function as pass through entities to bill the third-party customer. For consolidated joint ventures of this type, the Company records the entire amount of the services performed and the costs associated with these services, including the services provided by the other joint venture partners, in the Company’s result of operations. For certain of these joint ventures where a fee is added by an unconsolidated joint venture to client billings, the Company’s portion of that fee is recorded in equity in earnings of joint ventures. The Company also has joint ventures that have their own employees and operating expenses, and to which the Company generally makes a capital contribution. The Company accounts for these joint ventures either as consolidated entities or equity method investments based on the criteria further discussed below. The Company follows guidance on the consolidation of variable interest entities (VIEs) that requires companies to utilize a qualitative approach to determine whether it is the primary beneficiary of a VIE. The process for identifying the primary beneficiary of a VIE requires consideration of the factors that indicate a party has the power to direct the activities that most significantly impact the joint venture’s economic performance, including powers granted to the joint venture’s program manager, powers contained in the joint venture governing board and, to a certain extent, a company’s economic interest in the joint venture. The Company analyzes its joint ventures and classifies them as either: ● a VIE that must be consolidated because the Company is the primary beneficiary or the joint venture is not a VIE and the Company holds the majority voting interest with no significant participative rights available to the other partners; or ● a VIE that does not require consolidation and is treated as an equity method investment because the Company is not the primary beneficiary or the joint venture is not a VIE and the Company does not hold the majority voting interest. As part of the above analysis, if it is determined that the Company has the power to direct the activities that most significantly impact the joint venture’s economic performance, the Company considers whether or not it has the obligation to absorb losses or rights to receive benefits of the VIE that could potentially be significant to the VIE. Contractually required support provided to the Company’s joint ventures is discussed in Note 18. Summary of financial information of the consolidated joint ventures is as follows: September 30, September 30, 2021 2020 (in millions) Current assets $ 503.9 $ 536.3 Non-current assets 74.8 77.0 Total assets $ 578.7 $ 613.3 Current liabilities $ 400.3 $ 409.9 Non-current liabilities 1.5 1.5 Total liabilities 401.8 411.4 Total AECOM equity 74.0 113.9 Noncontrolling interests 102.9 88.0 Total owners’ equity 176.9 201.9 Total liabilities and owners’ equity $ 578.7 $ 613.3 Total revenue of the consolidated joint ventures was $826.8 million, $787.6 million, and $1,095.2 million for the years ended September 30, 2021, 2020 and 2019, respectively. The assets of the Company’s consolidated joint ventures are restricted for use only by the particular joint venture and are not available for the general operations of the Company. Summary of financial information of the unconsolidated joint ventures, as derived from their unaudited financial statements, is as follows: September 30, September 30, 2021 2020 (in millions) Current assets $ 1,323.2 $ 1,374.3 Non-current assets 1,001.6 465.8 Total assets $ 2,324.8 $ 1,840.2 Current liabilities $ 845.8 $ 953.4 Non-current liabilities 537.2 58.9 Total liabilities 1,383.0 1,012.3 Joint ventures’ equity 941.8 827.9 Total liabilities and joint ventures’ equity $ 2,324.8 $ 1,840.2 AECOM’s investment in joint ventures $ 328.9 $ 297.6 Twelve Months Ended September 30, September 30, 2021 2020 (in millions) Revenue $ 2,096.5 $ 3,058.9 Cost of revenue 2,051.2 2,993.1 Gross profit $ 45.3 $ 65.8 Net income $ 37.0 $ 59.8 Summary of AECOM’s equity in earnings of unconsolidated joint ventures is as follows: Fiscal Year Ended September 30, September 30, September 30, 2021 2020 2019 (in millions) Pass through joint ventures $ 23.6 $ 34.1 $ 31.6 Other joint ventures 11.4 14.7 17.7 Total $ 35.0 $ 48.8 $ 49.3

Pension Benefit Obligations

Pension Benefit Obligations	12 Months Ended
Pension Benefit Obligations	Sep. 30, 2021
Pension Benefit Obligations
Pension Benefit Obligations	7. Pension Benefit Obligations In the U.S., the Company sponsors various qualified defined benefit pension plans. Benefits under these plans generally are based on the employee’s years of creditable service and compensation; however, all U.S. defined benefit plans are closed to new participants and have frozen accruals. The Company also sponsors various non-qualified plans in the U.S.; all of these plans are frozen. Outside the U.S., the Company sponsors various pension plans, which are appropriate to the country in which the Company operates, some of which are government mandated. The following tables provide reconciliations of the changes in the U.S. and international plans’ benefit obligations, reconciliations of the changes in the fair value of assets for the last three years ended September 30, and reconciliations of the funded status as of September 30 of each year. Fiscal Year Ended September 30, September 30, September 30, 2021 2020 2019 U.S. Int’l U.S. Int’l U.S. Int’l (in millions) Change in benefit obligation: Benefit obligation at beginning of year $ 283.9 $ 1,440.3 $ 275.6 $ 1,311.3 $ 257.1 $ 1,188.8 Service cost — 0.5 — 0.6 — 0.5 Participant contributions 0.1 0.3 — 0.3 0.1 0.3 Interest cost 4.3 21.6 6.8 22.4 9.5 29.7 Benefits and expenses paid (18.5) (48.6) (18.4) (42.9) (17.6) (41.3) Actuarial (gain) loss (3.7) (4.7) 22.0 82.8 27.8 206.5 Plan settlements (0.7) (5.9) (2.1) (4.1) (1.3) (3.7) Plan amendments — 0.4 — — — 5.2 Foreign currency translation (gain) loss — 66.9 — 69.9 — (74.7) Benefit obligation at end of year $ 265.4 $ 1,470.8 $ 283.9 $ 1,440.3 $ 275.6 $ 1,311.3 Fiscal Year Ended September 30, September 30, September 30, 2021 2020 2019 U.S. Int’l U.S. Int’l U.S. Int’l (in millions) Change in plan assets Fair value of plan assets at beginning of year $ 129.6 $ 1,166.2 $ 129.3 $ 1,068.8 $ 131.4 $ 965.9 Actual return on plan assets 14.7 61.1 11.7 59.5 4.5 180.3 Employer contributions 13.7 25.2 9.1 27.7 12.2 28.2 Participant contributions 0.1 0.3 — 0.3 0.1 0.3 Benefits and expenses paid (18.5) (48.6) (18.4) (42.9) (17.6) (41.3) Plan settlements (0.7) (5.9) (2.1) (4.1) (1.3) (3.7) Foreign currency translation gain (loss) — 53.5 — 56.9 — (60.9) Fair value of plan assets at end of year $ 138.9 $ 1,251.8 $ 129.6 $ 1,166.2 $ 129.3 $ 1,068.8 Fiscal Year Ended September 30, 2021 September 30, 2020 September 30, 2019 U.S. Int’l U.S. Int’l U.S. Int’l (in millions) Reconciliation of funded status: Funded status at end of year $ (126.5) $ (219.0) $ (154.3) $ (274.1) $ (146.3) $ (242.5) Contribution made after measurement date N/A N/A N/A N/A N/A N/A Net amount recognized at end of year $ (126.5) $ (219.0) $ (154.3) $ (274.1) $ (146.3) $ (242.5) The following table sets forth the amounts recognized in the consolidated balance sheets as of September 30, 2021, 2020 and 2019: Fiscal Year Ended September 30, 2021 September 30, 2020 September 30, 2019 U.S. Int’l U.S. Int’l U.S. Int’l (in millions) Amounts recognized in the consolidated balance sheets: Other non-current assets $ — $ 47.5 $ — $ 44.0 $ — $ 28.3 Accrued expenses and other current liabilities (9.1) — (9.4) — (9.0) — Pension benefit obligations (117.4) (266.5) (144.9) (318.1) (137.3) (270.8) Net amount recognized in the balance sheet $ (126.5) $ (219.0) $ (154.3) $ (274.1) $ (146.3) $ (242.5) The following table details the reconciliation of amounts in the consolidated statements of stockholders’ equity for the fiscal years ended September 30, 2021, 2020 and 2019: Fiscal Year Ended September 30, 2021 September 30, 2020 September 30, 2019 U.S. Int’l U.S. Int’l U.S. Int’l (in millions) Reconciliation of amounts in consolidated statements of stockholders’ equity: Prior service (cost) credit $ (0.1) $ (1.6) $ (0.1) $ (1.2) $ (0.7) $ (1.2) Net loss (116.5) (279.5) (134.5) (297.7) (122.4) (233.0) Total recognized in accumulated other comprehensive loss $ (116.6) $ (281.1) $ (134.6) $ (298.9) $ (123.1) $ (234.2) The components of net periodic benefit cost other than the service cost component are included in other income (expense) in the consolidated statement of operations. The following table details the components of net periodic benefit cost for the Company’s pension plans for fiscal years ended September 30, 2021, 2020 and 2019: Fiscal Year Ended September 30, 2021 September 30, 2020 September 30, 2019 U.S. Int’l U.S. Int’l U.S. Int’l (in millions) Components of net periodic benefit cost: Service costs $ — $ 0.5 $ — $ 0.6 $ — $ 0.5 Interest cost on projected benefit obligation 4.3 21.6 6.8 22.4 9.5 29.7 Expected return on plan assets (6.5) (43.5) (7.0) (37.5) (9.0) (38.1) Amortization of prior service costs (credits) — 0.1 0.1 0.1 0.1 (0.1) Amortization of net loss 5.9 9.2 4.7 8.6 3.7 4.1 Curtailment loss recognized — — 0.5 — — — Settlement loss recognized 0.2 0.8 0.6 0.5 0.2 0.8 Net periodic benefit cost $ 3.9 $ (11.3) $ 5.7 $ (5.3) $ 4.5 $ (3.1) The amount of applicable deferred income taxes included in other comprehensive income arising from a change in net prior service cost and net gain/loss was $9.3 million, $15.5 million, and $16.3 million in the years ended September 30, 2021, 2020 and 2019, respectively. Amounts included in accumulated other comprehensive loss as of September 30, 2021 that are expected to be recognized as components of net periodic benefit cost during fiscal 2022 are (in millions): U.S. Int’l Amortization of prior service cost $ — $ (0.1) Amortization of net actuarial losses (5.6) (7.4) Total $ (5.6) $ (7.5) The table below provides additional year-end information for pension plans with accumulated benefit obligations in excess of plan assets. Fiscal Year Ended September 30, September 30, September 30, 2021 2020 2019 U.S. Int’l U.S. Int’l U.S. Int’l (in millions) Projected benefit obligation $ 247.8 $ 1,248.8 $ 265.1 $ 1,216.6 $ 257.3 $ 1,141.9 Accumulated benefit obligation 247.8 1,243.9 265.1 1,211.5 257.3 1,132.7 Fair value of plan assets 138.9 982.4 129.6 898.5 129.3 871.2 Funding requirements for each pension plan are determined based on the local laws of the country where such pension plan resides. In certain countries, the funding requirements are mandatory while in other countries, they are discretionary. The Company currently intends to contribute $24.8 million to the international plans in fiscal 2022. The required minimum contributions for U.S. plans are not significant. In addition, the Company may make discretionary contributions. The Company currently intends to contribute $11.4 million to U.S. plans in fiscal 2022. The table below provides the expected future benefit payments, in millions: Year Ending September 30, U.S. Int’l 2022 $ 21.0 $ 58.6 2023 21.4 57.4 2024 20.0 58.6 2025 19.7 60.1 2026 19.6 61.9 2027-2031 83.6 339.1 Total $ 185.3 $ 635.7 The underlying assumptions for the pension plans are as follows: Fiscal Year Ended September 30, September 30, September 30, 2021 2020 2019 U.S. Int’l U.S. Int’l U.S. Int’l (in millions) Weighted-average assumptions to determine benefit obligation: Discount rate 2.46 % 1.98 % 2.20 % 1.67 % 2.92 % 1.81 % Salary increase rate N/A 3.13 % N/A 2.68 % N/A 2.52 % Weighted-average assumptions to determine net periodic benefit cost: Discount rate 2.20 % 1.67 % 2.92 % 1.81 % 4.10 % 2.91 % Salary increase rate N/A 2.68 % N/A 2.52 % N/A 2.79 % Expected long-term rate of return on plan assets 6.80 % 3.95 % 7.30 % 4.03 % 7.00 % 4.43 % Pension costs are determined using the assumptions as of the beginning of the plan year. The funded status is determined using the assumptions as of the end of the plan year. The following table summarizes the Company’s target allocation for 2021 and pension plan asset allocation, both U.S. and international, as of September 30, 2021 and 2020: Percentage of Plan Assets as of September 30, Target Allocations 2021 2020 U.S. Int’l U.S. Int’l U.S. Int’l Asset Category: Equities 40 % 34 % 41 % 34 % 47 % 26 % Debt 48 54 44 53 42 54 Cash 2 2 5 3 1 4 Property and other 10 10 10 10 10 16 Total 100 % 100 % 100 % 100 % 100 % 100 % The Company’s domestic and foreign plans seek a competitive rate of return relative to an appropriate level of risk depending on the funded status and obligations of each plan and typically employ both active and passive investment management strategies. The Company’s risk management practices include diversification across asset classes and investment styles and periodic rebalancing toward asset allocation targets. The target asset allocation selected for each plan reflects a risk/return profile that the Company believes is appropriate relative to each plan’s liability structure and return goals. To develop the expected long-term rate of return on assets assumption, the Company considered the historical returns and the future expectations for returns for each asset class, as well as the target asset allocation of the pension portfolio and the diversification of the portfolio. This resulted in the selection of a 6.80% and 3.95% weighted-average long-term rate of return on assets assumption for the fiscal year ended September 30, 2021 for U.S. and non-U.S. plans, respectively. As of September 30, 2021, the fair values of the Company’s pension plan assets by major asset categories were as follows: Fair Value Measurement as of September 30, 2021 Total Quoted Significant Carrying Prices in Other Significant Value as of Active Observable Unobservable Investments September 30, Markets Inputs Inputs measured at 2021 (Level 1) (Level 2) (Level 3) NAV (in millions) Cash and cash equivalents $ 49.8 $ 25.1 $ 24.7 $ — $ — Equity and debt securities 488.5 488.5 — — — Investment funds: Diversified and equity funds 81.2 60.5 16.7 4.0 — Fixed income funds 29.3 25.0 4.3 — — Common collective funds 734.8 — — — 734.8 Derivative instruments 7.1 — 7.1 — — Total $ 1,390.7 $ 599.1 $ 52.8 $ 4.0 $ 734.8 As of September 30, 2020, the fair values of the Company’s pension plan assets by major asset categories were as follows: Fair Value Measurement as of September 30, 2020 Total Quoted Significant Carrying Prices in Other Significant Value as of Active Observable Unobservable Investments September 30, Markets Inputs Inputs measured at 2020 (Level 1) (Level 2) (Level 3) NAV (in millions) Cash and cash equivalents $ 50.6 $ 20.2 $ 30.4 $ — $ — Equity and debt securities 442.3 442.3 — — — Investment funds: Diversified and equity funds 31.5 13.0 15.1 3.4 — Fixed income funds 36.2 23.1 13.1 — — Common collective funds 707.5 — — — 707.5 Derivative instruments 27.7 — 27.7 — — Total $ 1,295.8 $ 498.6 $ 86.3 $ 3.4 $ 707.5 Changes for the year ended September 30, 2021 in the fair value of the Company’s recurring post-retirement plan Level 3 assets are as follows: Actual return Actual return on plan assets, on plan assets, Change September 30, relating to relating to Transfer due to 2020 assets still assets sold Purchases, into / exchange September 30, Beginning held at during the sales and (out of) rate 2021 balance reporting date period settlements Level 3 changes Ending balance (in millions) Level 3 Assets $ 3.4 $ 0.4 $ — $ 0.2 $ — $ — $ 4.0 Changes for the year ended September 30, 2020, in the fair value of the Company’s recurring post-retirement plan Level 3 assets are as follows: Actual return Actual return on plan assets, on plan assets, Change September 30, relating to relating to Transfer due to 2019 assets still assets sold Purchases, into / exchange September 30, Beginning held at during the sales and (out of) rate 2020 balance reporting date period settlements Level 3 changes Ending balance (in millions) Level 3 Assets $ 26.8 $ (0.2) $ (2.1) $ (25.4) $ 3.2 $ 1.1 $ 3.4 Cash equivalents are mostly comprised of short-term money-market instruments and are valued at cost, which approximates fair value. For investment funds not traded on an active exchange, or if the closing price is not available, the trustee obtains indicative quotes from a pricing vendor, broker, or investment manager. These funds are categorized as Level 2 if the custodian obtains corroborated quotes from a pricing vendor or categorized as Level 3 if the custodian obtains uncorroborated quotes from a broker or investment manager. Fixed income investment funds, not traded on an active exchange, categorized as Level 2 are valued by the trustee using pricing models that use verifiable observable market data (e.g., interest rates and yield curves observable at commonly quoted intervals), bids provided by brokers or dealers, or quoted prices of securities with similar characteristics. Hedge funds categorized as Level 3 are valued based on valuation models that include significant unobservable inputs and cannot be corroborated using verifiable observable market data. Hedge funds are valued by independent administrators. Depending on the nature of the assets, the general partners or independent administrators use both the income and market approaches in their models. The market approach consists of analyzing market transactions for comparable assets while the income approach uses earnings or the net present value of estimated future cash flows adjusted for liquidity and other risk factors. As of September 30, 2021, there were no material changes to the valuation techniques. Common collective funds are valued based on net asset value (NAV) per share or unit as a practical expedient as reported by the fund manager, multiplied by the number of shares or units held as of the measurement date. Accordingly, these NAV-based investments have been excluded from the fair value hierarchy. These collective investment funds have minimal redemption notice periods and are redeemable daily at the NAV, less transaction fees, without significant restrictions. There are no significant unfunded commitments related to these investments. Multiemployer Pension Plans The Company participates in construction-industry multiemployer pension plans. Generally, the plans provide defined benefits to substantially all employees covered by collective bargaining agreements. Under the Employee Retirement Income Security Act, a contributor to a multiemployer plan is liable, upon termination or withdrawal from a plan, for its proportionate share of a plan’s unfunded vested liability. The Company’s aggregate contributions to these multiemployer plans were $3.7 million and $4.0 million for the years ended September 30, 2021 and 2020, respectively. At September 30, 2021 and 2020, none of the plans in which the Company participates are individually significant to its consolidated financial statements.

Debt

Debt	12 Months Ended
Debt	Sep. 30, 2021
Debt
Debt	8. Debt Debt consisted of the following: September 30, September 30, 2021 2020 (in millions) Credit Agreement $ 1,155.3 $ 248.5 2024 Senior Notes — 797.3 2027 Senior Notes 997.3 997.3 Other debt 83.0 41.9 Total debt 2,235.6 2,085.0 Less: Current portion of debt and short-term borrowings (53.8) (20.9) Less: Unamortized debt issuance costs (24.1) (23.0) Long-term debt $ 2,157.7 $ 2,041.1 The following table presents, in millions, scheduled maturities of the Company’s debt as of September 30, 2021: Fiscal Year 2022 $ 53.8 2023 45.9 2024 41.0 2025 35.1 2026 400.4 Thereafter 1,659.4 Total $ 2,235.6 Credit Agreement On February 8, 2021, the Company entered into the 2021 Refinancing Amendment to the Credit Agreement (the “Credit Agreement”), pursuant to which the Company amended and restated its Syndicated Credit Facility Agreement, dated as of October 17, 2014 (as amended prior to February 8, 2021, the “Original Credit Agreement”), between the Company, as borrower, Bank of America, N.A., as administrative agent, and other parties thereto. The Credit Agreement consists of a $1,150,000,000 revolving credit facility (the “Revolving Credit Facility”) and a $246,968,737.50 term loan A facility (the “Term A Facility,” together with the Revolving Credit Facility, the “Credit Facilities”), each of which mature on February 8, 2026. The outstanding loans under the Term A Facility were borrowed in U.S. dollars. Loans under the Revolving Credit Facility may be borrowed, and the Letters of Credit thereunder may be issued, in U.S. dollars or certain foreign currencies. The proceeds of the Revolving Credit Facility may be used from time to time for ongoing working capital and for other general corporate purposes. The proceeds of the Revolving Credit Facility and the Term A Loan facility borrowed on February 8, 2021 were used to refinance the existing revolving credit facility and the existing term loan facility under the Original Credit Agreement and to pay related fees and expenses. The Credit Agreement permits and the Company to designate certain of its subsidiaries as additional co-borrowers from time to time. Currently, there are no co-borrowers under the Credit Facilities. The applicable interest rate under the Credit Agreement is calculated at a per annum rate equal to, at the Company’s option, (a) the Eurocurrency Rate (as defined in the Credit Agreement) plus an applicable margin (the “LIBOR Applicable Margin”), which is currently at 1.50% or (b) the Base Rate (as defined in the Credit Agreement) plus an applicable margin (the “Base Rate Applicable Margin” and together with the LIBOR Applicable Margin, the “Applicable Margins”), which is currently at 0.50%. The Credit Agreement includes certain environmental, social and governance (ESG) metrics relating to the Company’s CO 2 Some of the Company’s material subsidiaries (the “Guarantors”) have guaranteed the Company’s obligations of the borrowers under the Credit Agreement, subject to certain exceptions. The borrowers’ obligations under the Credit Agreement are secured by a lien on substantially all of the Company’s assets and its Guarantors’ assets, subject to certain exceptions. The Credit Agreement contains customary negative covenants that include, among other things, limitations on the ability of the Company and certain of its subsidiaries, subject to certain exceptions, to incur liens and debt, make investments, dispositions, and restricted payments, change the nature of their business, consummate mergers, consolidations and the sale of all or substantially all of their respective assets, taken as a whole, and transact with affiliates. The Company is also required to maintain a consolidated interest coverage ratio of at least 3.00 to 1.00 and a consolidated leverage ratio of less than or equal to 4.00 to 1.00 (subject to certain adjustments in connection with permitted acquisitions), tested on a quarterly basis (the “Financial Covenants”). The Company’s consolidated leverage ratio was 2.4 at September 30, 2021. As of September 30, 2021, the Company was in compliance with the covenants of the Credit Agreement. The Credit Agreement contains customary affirmative covenants, including, among other things, compliance with applicable law, preservation of existence, maintenance of properties and of insurance, and keeping proper books and records. The Credit Agreement contains customary events of default, including, among other things, nonpayment of principal, interest or fees, cross-defaults to other debt, inaccuracies of representations and warranties failure to perform covenants, events of bankruptcy and insolvency, change of control and unsatisfied judgments, subject in certain cases to notice and cure periods and other exceptions. On April 13, 2021, the Company entered into Amendment No. 10 to the Credit Agreement, pursuant to which the lenders thereunder provided a secured term “B” credit facility (the “Term B Facility”) to the Company in an aggregate principal amount of $700,000,000. The Term B Facility matures on April 13, 2028. The proceeds of the Term B Facility were used to fund the purchase price, fees and expenses in connection with the Company’s cash tender offer to purchase up to $700,000,000 aggregate purchase price (not including any accrued and unpaid interest) of its outstanding 5.875% Senior Notes due 2024. The Term B Facility is subject to the same affirmative and negative covenants and events of default as the Term A Facility previously incurred pursuant to the existing Credit Agreement (except that the Financial Covenants in the Credit Agreement do not apply to the Term B Facility). The applicable interest rate for the Term B Facility is calculated at a per annum rate equal to, at the Company’s option, (a) the Eurocurrency Rate (as defined in the Credit Agreement) plus 1.75% or (b) the Base Rate (as defined in the Credit Agreement) plus 0.75%. On June 25, 2021, the Company entered into Amendment No. 11 to the Credit Agreement, pursuant to which the lenders have provided to the Company an additional $215,000,000 in aggregate principal amount under the Term A Facility. The Company used the net proceeds from the increase in the Term A Facility (together with cash on hand), to (i) redeem all of the Company’s remaining 5.875% Senior Notes due 2024 and (ii) pay fees and expenses related to such redemption. At September 30, 2021 and September 30, 2020, letters of credit totaled $5.2 million and $19.0 million, respectively, under the Company’s revolving credit facilities. As of September 30, 2021 and September 30, 2020, the Company had $1,144.8 million and $1,331.0 million, respectively, available under its revolving credit facility. 2024 Senior Notes On October 6, 2014, the Company completed a private placement offering of $800,000,000 aggregate principal amount of the unsecured 5.875% Senior Notes due 2024 (the “2024 Notes”). On June 25, 2021, the Company redeemed the remaining principal amount of the 2024 Notes outstanding at such time. The redemption price of the 2024 Notes was 115.108% of the remaining outstanding aggregate principal amount, amounting to $217.5 million, plus accrued and unpaid interest. The amounts paid were funded using the proceeds from the additional draw down from the Term A Facility described above and cash on hand. The redemption of the 2024 Notes in the third quarter of fiscal 2021 resulted in a $117.5 million prepayment premium, which was included in interest expense. 2027 Senior Notes On February 21, 2017, the Company completed a private placement offering of $1,000,000,000 aggregate principal amount of its unsecured 5.125% Senior Notes due 2027 (the “2027 Senior Notes”). On June 30, 2017, the Company completed an exchange offer to exchange the unregistered 2027 Senior Notes for registered notes, as well as related guarantees. As of September 30, 2021, the estimated fair value of the 2027 Senior Notes was approximately $1,104.5 million. The fair value of the 2027 Senior Notes as of September 30, 2021 was derived by taking the mid-point of the trading prices from an observable market input (Level 2) in the secondary bond market and multiplying it by the outstanding balance of the 2027 Senior Notes. Interest is payable on the 2027 Senior Notes at a rate of 5.125% per annum. Interest on the 2027 Senior Notes is payable semi-annually on March 15 and September 15 of each year, commencing on September 15, 2017. The 2027 Senior Notes will mature on March 15, 2027. At any time and from time to time prior to December 15, 2026, the Company may redeem all or part of the 2027 Senior Notes, at a redemption price equal to 100% of their principal amount, plus a “make whole” premium as of the redemption date, and accrued and unpaid interest to the redemption date. On or after December 15, 2026, the Company may redeem all or part of the 2027 Notes at a redemption price equal to 100% of their principal amount, plus accrued and unpaid interest on the redemption date. The indenture pursuant to which the 2027 Senior Notes were issued contains customary events of default, including, among other things, payment default, exchange default, failure to provide notices thereunder and provisions related to bankruptcy events. The indenture also contains customary negative covenants. The Company was in compliance with the covenants relating to the 2027 Senior Notes as of September 30, 2021. URS Senior Notes In connection with the 2014 acquisition of the URS Corporation (URS), the Company assumed the URS 5.00% Senior Notes due 2022 (the “2022 URS Senior Notes”). The remaining $248.5 million principal amount of the 2022 URS Senior Notes were fully redeemed on August 31, 2020 using proceeds from a $248.5 million secured delayed draw term loan facility under the Credit Agreement, at a redemption price that was 106.835% of the principal amount outstanding plus accrued and unpaid interest. The August 31, 2020 redemption resulted in a $17.0 million prepayment premium, which was included in interest expense during the year ended September 30, 2020. Other Debt and Other Items Other debt consists primarily of obligations under capital leases and loans, and unsecured credit facilities. The Company’s unsecured credit facilities are primarily used for standby letters of credit issued in connection with general and professional liability insurance programs and for contract performance guarantees. At September 30, 2021 and September 30, 2020, these outstanding standby letters of credit totaled $478.5 million and $510.1 million, respectively. As of September 30, 2021, the Company had $463.6 million available under these unsecured credit facilities. Effective Interest Rate The Company’s average effective interest rate on its total debt, including the effects of the interest rate swap agreements and excluding the effects of prepayment premiums included in interest expense, during the years ended September 30, 2021, 2020 and 2019 was 4.4%, 5.3% and 5.1%, respectively. Interest expense in the consolidated statements of operations included amortization of deferred debt issuance costs for the years ended September 30, 2021, 2020 and 2019 of $10.2 million, $5.4 million and $5.0 million, respectively.

Derivative Financial Instrument

Derivative Financial Instruments and Fair Value Measurements	12 Months Ended
	Sep. 30, 2021
Derivative Financial Instruments and Fair Value Measurements
Derivative Financial Instruments and Fair Value Measurements	9. Derivative Financial Instruments and Fair Value Measurements The Company uses interest rate derivative contracts to hedge interest rate exposures on the Company’s variable rate debt. The Company enters into foreign currency derivative contracts with financial institutions to reduce the risk that its cash flows and earnings will be adversely affected by foreign currency exchange rate fluctuations. The Company’s hedging program is not designated for trading or speculative purposes. The Company recognizes derivative instruments as either assets or liabilities on the accompanying consolidated balance sheets at fair value. The Company records changes in the fair value (i.e., gains or losses) of the derivatives that have been designated as accounting hedges in the accompanying consolidated statements of operations as cost of revenue, interest expense or to accumulated other comprehensive loss in the accompanying consolidated balance sheets. Cash Flow Hedges The Company uses interest rate swap agreements designated as cash flow hedges to fix the variable interest rates on portions of the Company’s debt. The Company initially reports any gain on the effective portion of a cash flow hedge as a component of accumulated other comprehensive loss. The gain or loss is subsequently reclassified to interest expense when the interest expense on the variable rate debt is recognized. If the hedged transaction becomes probable of not occurring, any gain or loss related to interest rate swap agreements would be recognized in other income. The notional principal, fixed rates and related effective and expiration dates of the Company’s outstanding interest rate swap agreements were as follows: September 30, 2021 Notional Amount Notional Amount Fixed Effective Expiration Currency (in millions) Rate Date Date USD 200.0 2.60 % March 2018 February 2023 USD 400.0 1.349 % February 2023 March 2028 September 30, 2020 Notional Amount Notional Amount Fixed Effective Expiration Currency (in millions) Rate Date Date USD 200.0 2.60 % March 2018 February 2023 Subsequent to the end of the third quarter of fiscal 2021, the Company entered into new interest rate swap agreements with a notional value of $400.0 million to manage the interest rate exposure of its variable rate loans. The new swaps will become effective February 2023 and terminate in March 2028. By entering into the swap agreements, the Company converted a portion of the LIBOR rate-based liability into a fixed rate liability. The Company will pay a fixed rate of 1.349% and receive payment at the prevailing one-month LIBOR. Other Foreign Currency Forward Contracts The Company uses foreign currency forward contracts which are not designated as accounting hedges to hedge intercompany transactions and other monetary assets or liabilities denominated in currencies other than the functional currency of a subsidiary. Gains and losses on these contracts were not material for the years ended September 30, 2021, 2020 and 2019. Fair Value Measurements The Company’s non-pension financial assets and liabilities recorded at fair values relate to derivative instruments and were not material at September 30, 2021 or 2020. See Note 17 for accumulated balances and reporting period activities of derivatives related to reclassifications out of accumulated other comprehensive income or loss for the years ended September 30, 2021, 2020 and 2019. Additionally, there were no material losses recognized in income due to amounts excluded from effectiveness testing from the Company’s interest rate swap agreements.

Concentration of Credit Risk

Concentration of Credit Risk	12 Months Ended
Concentration of Credit Risk	Sep. 30, 2021
Concentration of Credit Risk
Concentration of Credit Risk	10. Concentration of Credit Risk Financial instruments which potentially subject the Company to concentrations of credit risk consist principally of cash investments and trade receivables. The Company’s cash balances and short-term investments are maintained in accounts held by major banks and financial institutions located primarily in the U.S., Canada, Europe, Australia, Middle East and Hong Kong. If the Company extends significant credit to clients in a specific geographic area or industry, the Company may experience disproportionately high levels of default if those clients are adversely affected by factors particular to their geographic area or industry. Concentrations of credit risk with respect to trade receivables are limited due to the large number of customers comprising the Company’s customer base, including, in large part, governments, government agencies and quasi-government organizations, and their dispersion across many different industries and geographies. See Note 4 regarding the Company’s foreign revenues. In order to mitigate credit risk, the Company continually reviews the credit worthiness of its major private clients.

Leases

Leases	12 Months Ended
Leases	Sep. 30, 2021
Leases
Leases	11. Leases On October 1, 2019, the Company adopted FASB ASC 842 on a modified retrospective basis, which amended the accounting standards for leases. Accordingly, the Company applied the new guidance as of the date of adoption with a cumulative-effect adjustment recorded through equity. Prior periods have not been restated as a result of the adoption. Retained earnings decreased $87.8 million due to the adoption, primarily from impairment of the right-of-use assets associated with office building leases. The Company also applied transition elections that allow it to avoid reassessment of lease definition, classification, or direct costs relating to expired or expiring leases. Adoption of the new lease guidance did not significantly change the Company’s accounting for finance leases, which were previously referred to as capital leases. The Company and its subsidiaries are lessees in non-cancelable leasing agreements for office buildings and equipment. Substantially all of the Company’s office building leases are operating leases, and its equipment leases are both operating and finance leases. The Company groups lease and non-lease components for its equipment leases into a single lease component but separates lease and non-lease components for its office building leases. The Company recognizes a right-of-use asset and lease liability for its operating leases at the commencement date equal to the present value of the contractual minimum lease payments over the lease term. The present value is calculated using the rate implicit in the lease, if known, or the Company’s incremental secured borrowing rate. The discount rate used for operating leases is primarily determined based on an analysis the Company’s incremental secured borrowing rate, while the discount rate used for finance leases is primarily determined by the rate specified in the lease. The related lease payments are expensed on a straight-line basis over the lease term, including, as applicable, any free-rent period during which the Company has the right to use the asset. For leases with renewal options where the renewal is reasonably assured, the lease term, including the renewal period, is used to determine the appropriate lease classification and to compute periodic rental expense. Leases with initial terms shorter than 12 months are not recognized on the balance sheet, and lease expense is recognized on a straight-line basis. The components of lease expenses are as follows: Fiscal Year Ended September 30, 2021 September 30, 2020 (in millions) Operating lease cost $ 186.5 $ 191.6 Finance lease cost: Amortization of right-of-use assets 13.0 17.1 Interest on lease liabilities 2.0 1.9 Variable lease cost 35.5 36.5 Total lease cost $ 237.0 $ 247.1 Additional balance sheet information related to leases is as follows: As of (in millions except as noted) Balance Sheet Classification September 30, 2021 September 30, 2020 Assets: Operating lease assets Operating lease right-of-use assets $ 607.1 $ 652.1 Finance lease assets Property and equipment – net 44.4 29.1 Total lease assets $ 651.5 $ 681.2 Liabilities: Current: Operating lease liabilities Accrued expenses and other current liabilities $ 157.3 $ 168.4 Finance lease liabilities Current portion of long-term debt 13.4 9.8 Total current lease liabilities 170.7 178.2 Non-current: Operating lease liabilities Operating lease liabilities, noncurrent 679.1 745.3 Finance lease liabilities Long-term debt 32.1 22.0 Total non-current lease liabilities $ 711.2 $ 767.3 As of September 30, 2021 September 30, 2020 Weighted average remaining lease term (in years): Operating leases 6.9 7.3 Finance leases 3.5 3.3 Weighted average discount rates: Operating leases 4.3 % 4.6 % Finance leases 4.3 % 4.7 % Additional cash flow information related to leases is as follows: Fiscal Year Ended September 30, September 30, 2021 2020 (in millions) Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 221.4 $ 208.7 Operating cash flows from finance leases 2.0 1.8 Financing cash flows from finance leases 13.7 14.7 Right-of-use assets obtained in exchange for new operating leases 102.7 126.9 Right-of-use assets obtained in exchange for new finance leases 28.5 26.4 Total remaining lease payments under both the Company’s operating and finance leases are as follows: Operating Leases Finance Leases Fiscal Year (in millions) 2022 $ 190.0 $ 15.2 2023 156.2 14.9 2024 134.7 11.7 2025 114.9 5.8 2026 91.6 1.5 Thereafter 286.8 — Total lease payments $ 974.2 $ 49.1 Less: Amounts representing interest $ (137.8) $ (3.6) Total lease liabilities $ 836.4 $ 45.5

Stockholders' Equity

Stockholders' Equity	12 Months Ended
Stockholders' Equity	Sep. 30, 2021
Stockholders' Equity
Stockholders' Equity	12. Stockholders’ Equity Common Stock Units

Share-Based Payments

Share-Based Payments	12 Months Ended
Share-Based Payments	Sep. 30, 2021
Share-based Payments
Share-based Payments	13. Share-Based Payments Defined Contribution Plans Stock Incentive Plans During the three years in the period ended September 30, 2021, option activity was as follows: Number of Weighted Options Average (in millions) Exercise Price Balance, September 30, 2018 0.6 31.62 Granted — — Exercised — — Cancelled (0.5) (31.62) Balance, September 30, 2019 0.1 31.62 Granted 0.3 38.72 Exercised — — Cancelled — — Balance, September 30, 2020 0.4 36.41 Granted — — Exercised (0.1) 31.62 Cancelled — — Balance, September 30, 2021 0.3 38.72 Exercisable as of September 30, 2019 0.1 31.62 Exercisable as of September 30, 2020 0.1 31.62 Exercisable as of September 30, 2021 — — The fair value of the Company’s employee stock option awards is estimated on the date of grant. The expected term of awards granted represents the period of time the awards are expected to be outstanding. The risk-free interest rate is based on U.S. Treasury bond rates with maturities equal to the expected term of the option on the grant date. The Company uses historical data as a basis to estimate the probability of forfeitures. The weighted average grant-date fair value of stock options granted during the year ended September 30, 2020 was $11.30. The Company grants stock units to employees under its Performance Earnings Program (PEP), whereby units are earned and issued dependent upon meeting established cumulative performance objectives and vest over a three-year service period. Additionally, the Company issues restricted stock units to employees which are earned based on service conditions. The grant date fair value of PEP awards and restricted stock unit awards is that day’s closing market price of the Company’s common stock. The weighted average grant date fair value of PEP awards was $52.76, $42.99, and $27.53 during the years ended September 30, 2021, 2020 and 2019, respectively. The weighted average grant date fair value of restricted stock unit awards was $49.21, $41.90 and $27.73 during the years ended September 30, 2021, 2020 and 2019, respectively. Total compensation expense related to these share-based payments including stock options was $44.7 million, $54.2 million, and $63.8 million during the years ended September 30, 2021, 2020 and 2019, respectively. Unrecognized compensation expense related to total share-based payments outstanding as of September 30, 2021 and 2020 was $45.6 million and $50.0 million, respectively, to be recognized on a straight-line basis over the awards’ respective vesting periods which are generally three years.

Income Taxes

Income Taxes	12 Months Ended
Income Taxes	Sep. 30, 2021
Income Taxes
Income Taxes	14. Income Taxes Income before income taxes included income from domestic operations of $98.6 million, $52.9 million, and $133.0 million for fiscal years ended September 30, 2021, 2020 and 2019 and income from foreign operations of $310.2 million, $179.7 million, and $116.2 million for fiscal years ended September 30, 2021, 2020 and 2019. Income tax expense was comprised of: Fiscal Year Ended September 30, September 30, September 30, 2021 2020 2019 (in millions) Current: Federal $ 32.2 $ 21.8 $ (17.3) State 6.8 12.7 29.8 Foreign 53.2 55.7 41.7 Total current income tax expense 92.2 90.2 54.2 Deferred: Federal (28.8) (21.8) (26.1) State 18.8 12.8 (24.6) Foreign 6.8 (35.4) 10.0 Total deferred income tax benefit (3.2) (44.4) (40.7) Total income tax expense $ 89.0 $ 45.8 $ 13.5 The major elements contributing to the difference between the U.S. federal statutory rate of 21% for fiscal years ended September 30, 2021, 2020 and 2019 and the effective tax rate are as follows: Fiscal Year Ended September 30, September 30, September 30, 2021 2020 2019 Amount % Amount % Amount % (in millions) Tax at federal statutory rate $ 85.8 21.0 % $ 48.8 21.0 % $ 52.0 21.0 % State income tax, net of federal benefit 8.0 2.0 8.4 3.6 7.0 2.8 Foreign residual income 45.6 11.1 39.5 17.0 35.8 14.5 Valuation allowance 12.4 3.0 (15.9) (6.9) (26.5) (10.7) Audit settlement 10.4 2.5 — — (4.6) (1.9) Foreign tax rate differential 8.8 2.1 3.2 1.4 (3.1) (1.3) Change in uncertain tax positions 8.5 2.1 (8.3) (3.6) 5.6 2.3 Nondeductible costs 6.0 1.5 15.8 6.8 7.6 3.1 Income tax credits and incentives (51.3) (12.5) (47.8) (20.6) (44.7) (18.1) Tax rate changes (26.8) (6.5) (0.5) (0.2) (1.9) (0.8) Return to provision (9.5) (2.3) 5.1 2.2 (0.2) (0.1) Exclusion of tax on non-controlling interests (6.1) (1.5) (3.4) (1.5) (5.3) (2.1) Tax exempt income (5.4) (1.3) (5.1) (2.2) (3.9) (1.6) Other items, net 2.6 0.6 6.0 2.7 (4.3) (1.7) Total income tax expense $ 89.0 21.8 % $ 45.8 19.7 % $ 13.5 5.4 % During fiscal 2021, the United Kingdom enacted a corporate tax rate increase from 19% to 25% beginning April 2023 requiring deferred tax assets and liabilities to be remeasured. The remeasurement resulted in a $25.9 million tax benefit, which is included in tax rate changes above. During fiscal 2021, the Company partially settled its U.S. federal audit for fiscal 2015 and 2016 and recorded tax expense of $13.2 million due primarily to changes in tax attributes. During fiscal 2020, the Company approved a tax planning strategy and restructured certain operations in Canada which resulted in a release of a valuation allowance related to net operating losses and other deferred tax assets of $31.7 million. The Company is now forecasting the utilization of the net operating losses within the foreseeable future. The positive evidence was evaluated against any negative evidence to determine the valuation allowance was no longer needed. During fiscal 2019, the Company reevaluated a valuation allowance of $38.1 million against foreign tax credits in the U.S. based on new positive evidence related to the issuance of regulations related to The Tax Cuts and Jobs Act The Company is currently under tax audit in several jurisdictions including the U.S and believe the outcomes which are reasonably possible within the next twelve months, including lapses in statutes of limitations, could result in adjustments, but will not result in a material change in the liability for uncertain tax positions. Generally, the Company would reverse its valuation allowance in a particular tax jurisdiction if the positive evidence examined, such as projected and sustainable earnings or a tax-planning strategy that allows for the usage of the deferred tax asset, is sufficient to overcome significant negative evidence, such as large net operating loss carryforwards or a cumulative history of losses in recent years. In the United States, the valued deferred tax assets have a restricted life or use under relevant tax law and, therefore, it is unlikely that the valuation allowance related to these assets will reverse. In addition, the Company is continually investigating tax planning strategies that, if prudent and feasible, may be implemented to realize a deferred tax asset that would otherwise expire unutilized. The identification and internal/external approval (as relevant) of such a prudent and feasible tax planning strategy could cause a reduction in the valuation allowance. The deferred tax assets (liabilities) are as follows: Fiscal Year Ended September 30, September 30, 2021 2020 (in millions) Deferred tax assets: Compensation and benefit accruals not currently deductible $ 130.0 $ 119.4 Net operating loss carryforwards 169.8 173.2 Self-insurance reserves 12.3 17.6 Research and experimentation and other tax credits 117.2 112.9 Pension liability 87.7 95.1 Accrued liabilities 284.7 307.6 Capital loss carryforward 62.0 104.8 Other 37.3 26.0 Total deferred tax assets 901.0 956.6 Deferred tax liabilities: Unearned revenue (19.8) (40.3) Depreciation and amortization (116.5) (106.7) Acquired intangible assets (19.4) (24.5) Investment in subsidiaries (13.4) (10.9) Right of use assets (145.6) (164.9) Contingent consideration (33.8) (33.6) Total deferred tax liabilities (348.5) (380.9) Valuation allowance (197.7) (217.5) Net deferred tax assets $ 354.8 $ 358.2 As of September 30, 2021, and 2020, the Company has available unused foreign and state net operating loss (NOL) carryforwards of $667.0 million and $710.2 million, respectively, which expire at various dates over the next several years and capital loss carryforwards of $184.1 million and $355.7 million, respectively, which expire in 2025 and 2026; some foreign NOL carryforwards never expire. In addition, as of September 30, 2021, the Company has unused federal and state research and development credits of $75.7 million and $23.4 million, respectively, and other credits of $18.1 million which expire at various dates over the next several years. As of September 30, 2021, and 2020, gross deferred tax assets were $901.0 million and $956.6 million, respectively. The Company has recorded a valuation allowance of $197.7 million and $217.5 million as of September 30, 2021 and 2020, respectively, primarily related to foreign and state net operating loss carryforwards, capital loss carryforwards, tax credits and other deferred tax assets. The Company has performed an assessment of positive and negative evidence, including the nature, frequency, and severity of cumulative financial reporting losses in recent years, the future reversal of existing temporary differences, predictability of future taxable income exclusive of reversing temporary differences of the character necessary to realize the asset, relevant carryforward periods, taxable income in carry-back years if carry-back is permitted under tax law, and prudent and feasible tax planning strategies that would be implemented, if necessary, to protect against the loss of the deferred tax asset that would otherwise expire. Although realization is not assured, based on the Company’s assessment, the Company has concluded that it is more likely than not that the remaining gross deferred tax asset (exclusive of deferred tax liabilities) of $703.3 million will be realized and, as such, no additional valuation allowance has been provided. The net decrease in the valuation allowance of $19.8 million is primarily attributable to a decrease in valuation allowances of $49.5 million related to capital losses, partially offset by increases in valuation allowances of $29.6 million for foreign unbenefitable losses. Generally, the Company does not provide for U.S. taxes or foreign withholding taxes on gross book-tax differences in its non-U.S. subsidiaries because such basis differences of approximately $1.5 billion are able to and intended to be reinvested indefinitely. If these basis differences were distributed, foreign tax credits could become available under current law to partially or fully reduce the resulting U.S. income tax liability. There may also be additional U.S. or foreign income tax liability upon repatriation, although the calculation of such additional taxes is not practicable. As of September 30, 2021, and 2020, the Company had a liability for unrecognized tax benefits, including potential interest and penalties, net of related tax benefit, totaling $62.8 million and $65.8 million, respectively. The gross unrecognized tax benefits as of September 30, 2021 and 2020 were $46.4 million and $47.1 million, respectively, excluding interest, penalties, and related tax benefit. Of the $46.4 million, approximately $40.1 million would be included in the effective tax rate if recognized. A reconciliation of the beginning and ending amount of gross unrecognized tax benefits is as follows: Fiscal Year Ended September 30, September 30, 2021 2020 (in millions) Balance at the beginning of the year $ 47.1 $ 55.7 Gross increase in current period’s tax positions 4.3 2.8 Gross increase in prior years’ tax positions 7.5 — Gross decrease in prior years’ tax positions — (7.9) Decrease due to settlement with tax authorities (1.3) (0.5) Decrease due to lapse of statute of limitations — (3.5) Gross change due to foreign exchange fluctuations (11.2) 0.5 Balance at the end of the year $ 46.4 $ 47.1 The Company classifies interest and penalties related to uncertain tax positions within the income tax expense line in the accompanying consolidated statements of operations. As of September 30, 2021, the accrued interest and penalties were $20.0 million and $3.9 million, respectively, excluding any related income tax benefits. As of September 30, 2020, the accrued interest and penalties were $18.9 million and $2.7 million, respectively, excluding any related income tax benefits. The Company files income tax returns in numerous tax jurisdictions, including the U.S., and numerous U.S. states and non-U.S. jurisdictions around the world. The statute of limitations varies by jurisdiction in which the Company operates. Because of the number of jurisdictions in which the Company files tax returns, in any given year the statute of limitations in certain jurisdictions may expire without examination within the 12-month period from the balance sheet date. While it is reasonably possible that the total amounts of unrecognized tax benefits could significantly increase or decrease within the next twelve months, an estimate of the range of possible change cannot be made.

Earnings Per Share

Earnings Per Share	12 Months Ended
Earnings Per Share	Sep. 30, 2021
Earnings Per Share
Earnings Per Share	15. Earnings Per Share Basic earnings per share (EPS) excludes dilution and is computed by dividing net income attributable to AECOM by the weighted average number of common shares outstanding for the period. Diluted EPS is computed by dividing net income attributable to AECOM by the weighted average number of common shares outstanding and potential common shares for the period. The Company includes as potential common shares the weighted average dilutive effects of equity awards using the treasury stock method. For the periods presented, equity awards excluded from the calculation of potential common shares were not significant. The following table sets forth a reconciliation of the denominators of basic and diluted earnings per share: Fiscal Year Ended September 30, September 30, September 30, 2021 2020 2019 (in millions) Denominator for basic earnings per share 147.3 159.0 157.0 Potential common shares 2.4 2.3 2.7 Denominator for diluted earnings per share 149.7 161.3 159.7

Other Financial Information

Other Financial Information	12 Months Ended
Other Financial Information	Sep. 30, 2021
Other Financial Information
Other Financial Information	16. Other Financial Information Accrued expenses and other current liabilities consist of the following: Fiscal Year Ended September 30, September 30, 2021 2020 (in millions) Accrued salaries and benefits $ 661.8 $ 675.7 Accrued contract costs 1,202.1 1,137.5 Other accrued expenses 310.3 436.5 $ 2,174.2 $ 2,249.7 Accrued contract costs above include balances related to professional liability accruals of $736.4 million and $596.0 million as of September 30, 2021 and 2020, respectively. The remaining accrued contract costs primarily relate to costs for services provided by subcontractors and other non-employees. Liabilities recorded related to accrued contract losses were not material as of September 30, 2021 and 2020. The Company did not have material revisions to estimates for contracts where revenue is recognized using the percentage-of-completion method during the twelve months ended September 30, 2021. In the first quarter of fiscal 2019, the Company commenced a restructuring plan to improve profitability. The Company incurred restructuring expenses of $48.8 million, including personnel and other costs of $37.8 million and real estate costs of $11.0 million during the year ended September 30, 2021, of which $5.2 million was accrued and unpaid at September 30, 2021. The Company incurred restructuring expenses of $188.3 million, including personnel and other costs of $149.2 million and real estate costs of $39.1 million during the year ended September 30, 2020, of which $56.2 million was accrued and unpaid at September 30, 2020. In connection with this restructuring plan, the Company evaluated its real estate portfolio to better align with the ongoing business. The Company identified certain long-lived assets that were no longer recoverable, and recorded an impairment of $27.4 million in Impairment of long-lived assets, including goodwill during the fourth quarter of fiscal 2019. Fair value of the long-lived assets was determined primarily using Level 3 inputs, such as discounted cash flows.

Reclassifications out of Accumu

Reclassifications out of Accumulated Other Comprehensive Loss	12 Months Ended
	Sep. 30, 2021
Reclassifications out of Accumulated Other Comprehensive Loss
Reclassifications out of Accumulated Other Comprehensive Loss	17. Reclassifications out of Accumulated Other Comprehensive Loss The accumulated balances and reporting period activities for the years ended September 30, 2021, 2020 and 2019 related to reclassifications out of accumulated other comprehensive loss are summarized as follows (in millions): Foreign Accumulated Pension Currency Loss on Other Related Translation Derivative Comprehensive Adjustments Adjustments Instruments Loss Balances at September 30, 2018 $ (202.3) $ (502.2) $ 1.2 $ (703.3) Other comprehensive income (loss) before reclassification (107.2) (46.5) (17.2) (170.9) Amounts reclassified from accumulated other comprehensive loss 6.8 — 3.2 10.0 Balances at September 30, 2019 $ (302.7) $ (548.7) $ (12.8) $ (864.2) Foreign Accumulated Pension Currency Loss on Other Related Translation Derivative Comprehensive Adjustments Adjustments Instruments Loss Balances at September 30, 2019 $ (302.7) $ (548.7) $ (12.8) $ (864.2) Other comprehensive income (loss) before reclassification (72.5) (18.6) (5.3) (96.4) Amounts reclassified from accumulated other comprehensive loss 32.4 — 9.5 41.9 Balances at September 30, 2020 $ (342.8) $ (567.3) $ (8.6) $ (918.7) Foreign Accumulated Pension Currency Loss on Other Related Translation Derivative Comprehensive Adjustments Adjustments Instruments Loss Balances at September 30, 2020 $ (342.8) $ (567.3) $ (8.6) $ (918.7) Other comprehensive income (loss) before reclassification 14.6 (12.8) 0.8 2.6 Amounts reclassified from accumulated other comprehensive loss 12.0 — 3.7 15.7 Balances at September 30, 2021 $ (316.2) $ (580.1) $ (4.1) $ (900.4)

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Sep. 30, 2021
Commitments and Contingencies
Commitments and Contingencies	18. Commitments and Contingencies The Company records amounts representing its probable estimated liabilities relating to claims, guarantees, litigation, audits and investigations. The Company relies in part on qualified actuaries to assist it in determining the level of reserves to establish for insurance-related claims that are known and have been asserted against it, and for insurance-related claims that are believed to have been incurred based on actuarial analysis, but have not yet been reported to the Company’s claims administrators as of the respective balance sheet dates. The Company includes any adjustments to such insurance reserves in its consolidated results of operations. The Company’s reasonably possible loss disclosures are presented on a gross basis prior to the consideration of insurance recoveries. The Company does not record gain contingencies until they are realized. In the ordinary course of business, the Company may not be aware that it or its affiliates are under investigation and may not be aware of whether or not a known investigation has been concluded. In the ordinary course of business, the Company may enter into various arrangements providing financial or performance assurance to clients, lenders, or partners. Such arrangements include standby letters of credit, surety bonds, and corporate guarantees to support the creditworthiness or the project execution commitments of its affiliates, partnerships and joint ventures. Performance arrangements typically have various expiration dates ranging from the completion of the project contract and extending beyond contract completion in certain circumstances such as for warranties. The Company may also guarantee that a project, when complete, will achieve specified performance standards. If the project subsequently fails to meet guaranteed performance standards, the Company may incur additional costs, pay liquidated damages or be held responsible for the costs incurred by the client to achieve the required performance standards. The potential payment amount of an outstanding performance arrangement is typically the remaining cost of work to be performed by or on behalf of third parties. Generally, under joint venture arrangements, if a partner is financially unable to complete its share of the contract, the other partner(s) may be required to complete those activities. At September 30, 2021, the Company was contingently liable in the amount of approximately $483.0 million in issued standby letters of credit and $4.3 billion in issued surety bonds primarily to support project execution. In the ordinary course of business, the Company enters into various agreements providing financial or performance assurances to clients on behalf of certain unconsolidated partnerships, joint ventures and other jointly executed contracts. These agreements are entered into primarily to support the project execution commitments of these entities. The Company’s investment adviser jointly manages and sponsors the AECOM-Canyon Equity Fund, L.P. (the “Fund”), in which the Company indirectly holds an equity interest and has an ongoing capital commitment to fund investments. At September 30, 2021, the Company has capital commitments of $19.3 million to the Fund over the next 7 years. In addition, in connection with the investment activities of AECOM Capital, the Company provides guarantees of certain contractual obligations, including guarantees for completion of projects, repayment of debt, environmental indemnity obligations and other lender required guarantees. Department of Energy Deactivation, Demolition, and Removal Project AECOM Energy and Construction, Inc., an Ohio corporation, a former affiliate of the Company (“Former Affiliate”) executed a cost-reimbursable task order with the Department of Energy (DOE) in 2007 to provide deactivation, demolition and removal services at a New York State project site that, during 2010, experienced contamination and performance issues. In February 2011, the Former Affiliate and the DOE executed a Task Order Modification that changed some cost-reimbursable contract provisions to at-risk. The Task Order Modification, including subsequent amendments, required the DOE to pay all project costs up to $106 million, required the Former Affiliate and the DOE to equally share in all project costs incurred from $106 million to $146 million, and required the Former Affiliate to pay all project costs exceeding $146 million. Due to unanticipated requirements and permitting delays by federal and state agencies, as well as delays and related ground stabilization activities caused by Hurricane Irene in 2011, the Former Affiliate was required to perform work outside the scope of the Task Order Modification. In December 2014, the Former Affiliate submitted an initial set of claims against the DOE pursuant to the Contracts Disputes Acts seeking recovery of $103 million, including additional fees on changed work scope (the “2014 Claims”). On December 6, 2019, the Former Affiliate submitted a second set of claims against the DOE seeking recovery of an additional $60.4 million, including additional project costs and delays outside the scope of the contract as a result of differing site and ground conditions (the “2019 Claims”). The Former Affiliate also submitted three alternative breach of contract claims to the 2014 and 2019 Claims that may entitle the Former Affiliate to recovery of $148.5 million to $329.4 million. On December 30, 2019, the DOE denied the Former Affiliate’s 2014 Claims. On September 25, 2020, the DOE denied the Former Affiliate’s 2019 Claims. The Company filed an appeal of these decisions on December 20, 2020 in the Court of Federal Claims. Deconstruction, decommissioning and site restoration activities are complete. On January 31, 2020, the Company completed the sale of its Management Services business to the Purchaser including the Former Affiliate who worked on the DOE project. The Company and the Purchaser agreed that all future DOE project claim recoveries and costs will be split 10% to the Purchaser and 90% to the Company with the Company retaining control of all future strategic legal decisions. The Company intends to vigorously pursue all claimed amounts but can provide no certainty that the Company will recover 2014 and 2019 Claims submitted against the DOE, or any additional incurred claims or costs, which could have a material adverse effect on the Company’s results of operations. New York Department of Environmental Conservation In September 2017, AECOM USA, Inc. was advised by the New York State Department of Environmental Conservation (DEC) of allegations that it committed environmental permit violations pursuant to the New York Environmental Conservation Law (ECL) associated with AECOM USA, Inc.’s oversight of a stream restoration project for Schoharie County which could result in substantial penalties if calculated under the ECL’s maximum civil penalty provisions. AECOM USA, Inc. disputes this claim and intends to continue to defend this matter vigorously; however, AECOM USA, Inc. cannot provide assurances that it will be successful in these efforts. The potential range of loss in excess of any current accrual cannot be reasonably estimated at this time primarily because the matter involves complex and unique environmental and regulatory issues; the project site involves the oversight and involvement of various local, state and federal government agencies; there is substantial uncertainty regarding any alleged damages; and the matter is in its preliminary stages. Refinery Turnaround Project A Former Affiliate of the Company entered into an agreement to perform turnaround maintenance services during a planned shutdown at a refinery in Montana in December 2017. The turnaround project was completed in February 2019. Due to circumstances outside of the Company’s Former Affiliate’s control, including client directed changes and delays and the refinery’s condition, the Company’s Former Affiliate performed additional work outside of the original contract over $90 million and is entitled to payment from the refinery owner of approximately $144 million. In March 2019, the refinery owner sent a letter to the Company’s Former Affiliate alleging it incurred approximately $79 million in damages due to the Company’s Former Affiliate’s project performance. In April 2019, the Company’s Former Affiliate filed and perfected a $132 million construction lien against the refinery for unpaid labor and materials costs. In August 2019, following a subcontractor complaint filed in the Thirteen Judicial District Court of Montana asserting claims against the refinery owner and the Company’s Former Affiliate, the refinery owner crossclaimed against the Company’s Former Affiliate and the subcontractor. In October 2019, following the subcontractor’s dismissal of its claims, the Company’s Former Affiliate removed the matter to federal court and cross claimed against the refinery owner. In December 2019, the refinery owner claimed $93.0 million in damages and offsets against the Company’s Former Affiliate. The parties have agreed on a February 28, 2022 deadline for close of discovery in this matter. On January 31, 2020, the Company completed the sale of its Management Services business to the Purchaser including the Former Affiliate, however, the Refinery Turnaround Project, including related claims and liabilities, has been retained by the Company. The Company intends to vigorously prosecute and defend this matter; however, the Company cannot provide assurance that the Company will be successful in these efforts. The resolution of this matter and any potential range of loss cannot be reasonably determined or estimated at this time, primarily because the matter raises complex legal issues that Company is continuing to assess.

Reportable Segments and Geograp

Reportable Segments and Geographic Information	12 Months Ended
Reportable Segments and Geographic Information	Sep. 30, 2021
Reportable Segments and Geographic Information
Reportable Segments and Geographic Information	19. Reportable Segments and Geographic Information During the first quarter of fiscal 2020, the Company reorganized its operating and reporting structure to better align with its ongoing professional services business. This reorganization better reflects the continuing operations of the Company after the sale of its former Management Services reportable segment and planned disposal of its self-perform at-risk construction businesses discussed in Note 3. The businesses that comprised the Company's former Management Services reportable segment and the civil infrastructure, power and oil and gas construction businesses in the former Construction Services reportable segment were classified as discontinued operations. The former Design and Consulting Services reportable segment and construction management business in the former Construction Services reportable segment were reformed around geographic regions. The Americas segment provides planning, consulting, architectural and engineering design services, and construction management services to commercial and government clients in the United States, Canada, and Latin America, while the International segment provides similar professional services to commercial and government clients in Europe, the Middle East, Africa, and the Asia-Pacific regions. The Company’s AECOM Capital (ACAP) segment primarily invests in and develops real estate projects. These reportable segments are organized by the differing specialized needs of the respective clients, and how the Company manages its business. The Company has aggregated various operating segments into its reportable segments based on their similar characteristics, including similar long term financial performance, the nature of services provided, internal processes for delivering those services, and types of customers. The change in reportable segments was applied to all periods presented. AECOM Reportable Segments: Americas International Capital Corporate Total (in millions) Fiscal Year Ended September 30, 2021: Revenue $ 10,226.3 $ 3,112.6 $ 2.0 $ — $ 13,340.9 Gross profit 631.6 164.8 2.0 — 798.4 Equity in earnings of joint ventures 11.4 12.2 11.4 — 35.0 General and administrative expenses — — (11.1) (143.9) (155.0) Restructuring costs — — — (48.8) (48.8) Operating income 643.0 177.0 2.3 (192.7) 629.6 Segment assets 7,204.6 2,764.5 234.6 1,390.9 Gross profit as a % of revenue 6.2 % 5.3 % 6.0 % Fiscal Year Ended September 30, 2020: Revenue $ 10,131.5 $ 3,101.7 $ 6.8 $ — $ 13,240.0 Gross profit 580.5 122.2 6.9 — 709.6 Equity in earnings of joint ventures 19.8 14.3 14.7 — 48.8 General and administrative expenses — — (8.6) (180.0) (188.6) Restructuring costs — — — (188.3) (188.3) Operating income 600.3 136.5 13.0 (368.3) 381.5 Segment assets 8,104.4 2,454.0 198.0 1,625.8 Gross profit as a % of revenue 5.7 % 3.9 % 5.4 % Fiscal Year Ended September 30, 2019: Revenue $ 10,382.6 $ 3,251.7 $ 8.2 $ — $ 13,642.5 Gross profit 511.5 91.9 8.3 — 611.7 Equity in earnings of joint ventures 17.7 13.9 17.7 — 49.3 General and administrative expenses — — (5.0) (143.2) (148.2) Restructuring costs — — — (95.4) (95.4) Gain on disposal activities — 3.6 — — 3.6 Impairment of long lived assets (10.8) (4.4) — (9.7) (24.9) Operating income 518.4 105.0 21.0 (248.3) 396.1 Segment assets 7,437.3 2,247.1 197.8 718.4 Gross profit as a % of revenue 4.9 % 2.8 % 4.5 % Geographic Information: Fiscal Year Ended September 30, September 30, September 30, Long-Lived Assets 2021 2020 2019 (in millions) Americas 3,922.8 3,733.2 3,399.1 Europe, Middle East, Africa 872.3 875.8 738.8 Asia Pacific 405.0 375.3 272.4 Total 5,200.1 4,984.3 4,410.3 Long-lived assets consist of noncurrent assets excluding deferred tax assets.

Major Clients

Major Clients	12 Months Ended
Major Clients	Sep. 30, 2021
Major Clients
Major Clients	20. Major Clients No single client accounted for 10% or more of the Company’s revenue in any of the past five

Quarterly Financial Information

Quarterly Financial Information-Unaudited	12 Months Ended
Quarterly Financial Information-Unaudited	Sep. 30, 2021
Quarterly Financial Information-Unaudited
Quarterly Financial Information-Unaudited	21. Quarterly Financial Information—Unaudited In the opinion of management, the following unaudited quarterly data reflects all adjustments necessary for a fair statement of the results of operations. All such adjustments are of a normal recurring nature. First Second Third Fourth Fiscal Year 2021: Quarter Quarter Quarter Quarter (in millions, except per share data) Revenue $ 3,313.2 $ 3,265.5 $ 3,408.4 $ 3,353.8 Cost of revenue 3,128.8 3,070.3 3,206.8 3,136.6 Gross profit 184.4 195.2 201.6 217.2 Equity in earnings of joint ventures 8.2 7.2 8.2 11.4 General and administrative expenses (38.4) (36.0) (36.3) (44.3) Restructuring costs (13.0) (8.8) (13.0) (14.0) Income from operations 141.2 157.6 160.5 170.3 Other income 3.9 3.5 4.5 5.7 Interest expense (30.7) (32.8) (149.0) (25.9) Income from continuing operations before taxes 114.4 128.3 16.0 150.1 Income tax expense (benefit) for continuing operations 25.6 35.1 (17.8) 46.1 Net income from continuing operations 88.8 93.2 33.8 104.0 Net loss from discontinued operations (55.8) (47.9) (15.4) 2.3 Net income 33.0 45.3 18.4 106.3 Net income attributable to noncontrolling interests from continuing operations (5.4) (4.9) (5.9) (8.9) Net income attributable to noncontrolling interests from discontinued operations (1.5) (1.0) (1.0) (1.2) Net income attributable to noncontrolling interests (6.9) (5.9) (6.9) (10.1) Net income attributable to AECOM from continuing operations 83.4 88.3 27.9 95.1 Net loss attributable to AECOM from discontinued operations (57.3) (48.9) (16.4) 1.1 Net income attributable to AECOM $ 26.1 $ 39.4 $ 11.5 $ 96.2 Net income (loss) attributable to AECOM per share: Basic continuing operations per share $ 0.55 $ 0.60 $ 0.19 $ 0.66 Basic discontinued operations per share $ (0.38) $ (0.33) $ (0.11) $ 0.01 Basic earnings per share $ 0.17 $ 0.27 $ 0.08 $ 0.67 Diluted continuing operations per share $ 0.54 $ 0.59 $ 0.19 $ 0.65 Diluted discontinued operations per share $ (0.37) $ (0.33) $ (0.11) $ 0.01 Diluted earnings per share $ 0.17 $ 0.26 $ 0.08 $ 0.66 Weighted average shares outstanding: Basic 151.4 147.8 146.1 143.8 Diluted 153.7 149.5 148.9 146.6 First Second Third Fourth Fiscal Year 2020: Quarter Quarter Quarter Quarter (in millions, except per share data) Revenue $ 3,235.6 $ 3,245.7 $ 3,189.7 $ 3,569.0 Cost of revenue 3,069.8 3,076.9 3,004.6 3,379.1 Gross profit 165.8 168.8 185.1 189.9 Equity in earnings of joint ventures 9.9 13.5 8.6 16.8 General and administrative expenses (43.6) (41.0) (54.5) (49.5) Restructuring costs (44.9) (31.2) (20.3) (91.9) Income from operations 87.2 110.1 118.9 65.3 Other income 4.0 2.4 3.1 1.6 Interest expense (40.4) (37.1) (35.0) (47.5) Income from continuing operations before taxes 50.8 75.4 87.0 19.4 Income tax expense (benefit) for continuing operations 15.9 21.7 (7.2) 15.3 Net income from continuing operations 34.9 53.7 94.2 4.1 Net income (loss) from discontinued operations 18.2 (130.7) (0.1) (228.0) Net income (loss) 53.1 (77.0) 94.1 (223.9) Net income attributable to noncontrolling interests from continuing operations (4.0) (5.2) (3.1) (4.2) Net income attributable to noncontrolling interests from discontinued operations (8.5) (3.9) (1.6) (2.2) Net income attributable to noncontrolling interests (12.5) (9.1) (4.7) (6.4) Net income (loss) attributable to AECOM from continuing operations 30.9 48.5 91.1 (0.1) Net income (loss) attributable to AECOM from discontinued operations 9.7 (134.6) (1.7) (230.2) Net income (loss) attributable to AECOM $ 40.6 $ (86.1) $ 89.4 $ (230.3) Net income attributable to AECOM per share: Basic continuing operations per share $ 0.20 $ 0.31 $ 0.57 $ — Basic discontinued operations per share $ 0.06 $ (0.85) $ (0.01) $ (1.44) Basic earnings per share $ 0.26 $ (0.54) $ 0.56 $ (1.44) Diluted continuing operations per share $ 0.19 $ 0.30 $ 0.56 $ — Diluted discontinued operations per share $ 0.06 $ (0.84) $ (0.01) $ (1.44) Diluted earnings per share $ 0.25 $ (0.54) $ 0.55 $ (1.44) Weighted average shares outstanding: Basic 157.3 158.6 160.1 160.0 Diluted 160.6 160.7 161.8 160.0

Schedule II_ Valuation and Qual

Schedule II: Valuation and Qualifying Accounts	12 Months Ended
Schedule II: Valuation and Qualifying Accounts	Sep. 30, 2021
Schedule II: Valuation and Qualifying Accounts
Schedule II: Valuation and Qualifying Accounts	AECOM Technology Corporation Schedule II: Valuation and Qualifying Accounts (amounts in millions) Balance at Additions Other and Balance at Beginning Charged to Cost Foreign the End of of Year of Revenue Deductions (a) Exchange Impact the Year Allowance for Doubtful Accounts Fiscal Year 2021 $ 77.9 $ 29.1 $ (14.9) $ 0.7 $ 92.8 Fiscal Year 2020 $ 56.5 $ 37.6 $ (16.4) $ 0.2 $ 77.9 Fiscal Year 2019 $ 54.2 $ 23.9 $ (21.0) $ (0.6) $ 56.5 (a) Primarily relates to accounts written-off and recoveries

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
Significant Accounting Policies (Policies)	Sep. 30, 2021
Significant Accounting Policies
Fiscal Year	Fiscal Year
Use of Estimates	Use of Estimates
Principles of Consolidation and Presentation	Principles of Consolidation and Presentation
Government Contract Matters	Government Contract Matters Audits by the DCAA and other agencies consist of reviews of the Company’s overhead rates, operating systems and cost proposals to ensure that the Company accounted for such costs in accordance with the Cost Accounting Standards of the FAR (CAS). If the DCAA determines the Company has not accounted for such costs consistent with CAS, the DCAA may disallow these costs. There can be no assurance that audits by the DCAA or other governmental agencies will not result in material cost disallowances in the future.
Cash and Cash Equivalents	Cash and Cash Equivalents
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts ● Client type—federal or state and local government or commercial client; ● Historical contract performance; ● Historical collection and delinquency trends; ● Client credit worthiness; and ● General economic conditions.
Derivative Financial Instruments	Derivative Financial Instruments For derivative instruments that hedge the exposure to variability in expected future cash flows that are designated as cash flow hedges, the effective portion of the gain or loss on the derivative instrument is reported as a component of accumulated other comprehensive income in stockholders’ equity and reclassified into income in the same period or periods during which the hedged transaction affects earnings. The ineffective portion of the gain or loss on the derivative instrument, if any, is recognized in current income. To receive hedge accounting treatment, cash flow hedges must be highly effective in offsetting changes to expected future cash flows on hedged transactions. The net gain or loss on the effective portion of a derivative instrument that is designated as an economic hedge of the foreign currency translation exposure generated by the re-measurement of certain assets and liabilities denominated in a non-functional currency in a foreign operation is reported in the same manner as a foreign currency translation adjustment. Accordingly, any gains or losses related to these derivative instruments are recognized in current income. Derivatives that do not qualify as hedges are adjusted to fair value through current income.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amounts of cash and cash equivalents, accounts receivable and accounts payable approximate fair value because of the short maturities of these instruments. The carrying amount of the revolving credit facility approximates fair value because the interest rates are based upon variable reference rates. The Company’s fair value measurement methods may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. Although the Company believes its valuation methods are appropriate and consistent with those used by other market participants, the use of different methodologies or assumptions to determine fair value could result in a different fair value measurement at the reporting date.
Property and Equipment	Property and Equipment ten three three
Long-Lived Assets	Long-Lived Assets
Goodwill and Acquired Intangible Assets	Goodwill and Acquired Intangible Assets The Company tests goodwill for impairment annually for each reporting unit in the fourth quarter of the fiscal year and between annual tests, if events occur or circumstances change which suggest that goodwill should be evaluated. Such events or circumstances include significant changes in legal factors and business climate, recent losses at a reporting unit, and industry trends, among other factors. A reporting unit is defined as an operating segment or one level below an operating segment. The Company’s impairment tests are performed at the operating segment level as they represent the Company’s reporting units. During the impairment test, the Company estimates the fair value of the reporting unit using income and market approaches, and compares that amount to the carrying value of that reporting unit. In the event the fair value of the reporting unit is determined to be less than the carrying value, goodwill is impaired, and an impairment loss is recognized equal to the excess, limited to the total amount of goodwill allocated to the reporting unit. See also Note 3.
Pension Plans	Pension Plans
Insurance Reserves	Insurance Reserves
Foreign Currency Translation	Foreign Currency Translation The Company uses foreign currency forward contracts from time to time to mitigate foreign currency risk. The Company limits exposure to foreign currency fluctuations in most of its contracts through provisions that require client payments in currencies corresponding to the currency in which costs are incurred. As a result of this natural hedge, the Company generally does not need to hedge foreign currency cash flows for contract work performed.
Noncontrolling Interests	Noncontrolling Interests
Income Taxes	Income Taxes

Discontinued Operations, Good_2

Discontinued Operations, Goodwill, and Intangible Assets (Tables)	12 Months Ended
	Sep. 30, 2021
Discontinued Operations, Goodwill, and Intangible Assets
Summarized results of the discontinued operation, included in the Company's results of operations	The following table represents summarized balance sheet information of assets and liabilities held for sale (in millions): September 30, September 30, 2021 2020 Cash and cash equivalents $ 5.6 $ 109.9 Receivables and contract assets 90.3 414.3 Other 43.5 38.2 Current assets held for sale $ 139.4 $ 562.4 Property and equipment, net $ 52.9 $ 119.8 Other 18.5 181.8 Write-down of assets to fair value less cost to sell (71.4) (247.2) Non-current assets held for sale $ — $ 54.4 Accounts payable and accrued expenses $ 88.5 $ 350.4 Contract liabilities — 65.6 Other 5.5 1.6 Current liabilities held for sale $ 94.0 $ 417.6 Long-term liabilities held for sale $ 11.1 $ 79.3 The following table represents summarized income statement information of discontinued operations (in millions): Fiscal Year Ended September 30, September 30, 2021 2020 Revenue $ 771.5 $ 3,150.8 Cost of revenue 760.5 3,179.2 Gross profit (loss) 11.0 (28.4) Equity in earnings (losses) of joint ventures 4.0 (25.5) (Loss) gain on disposal activities (52.5) 161.9 Transaction costs (15.3) (43.2) Impairment of long-lived assets, including goodwill (105.2) (336.5) Loss from operations (158.0) (271.7) Other income — 1.8 Interest expense (0.5) (40.5) Loss before taxes (158.5) (310.4) Income tax (benefit) expense (41.7) 30.2 Net loss from discontinued operations $ (116.8) $ (340.6) The significant components included in the Consolidated Statement of Cash Flows for the discontinued operations are as follows (in millions): Fiscal Year Ended September 30, September 30, 2021 2020 Depreciation and amortization: Property and equipment $ — $ 4.6 Intangible assets and capitalized debt issuance costs — 26.0 Payments for capital expenditures (7.3) (19.6)
Schedule of changes in the carrying value of goodwill by reportable segment	Foreign September 30, Exchange September 30, 2020 Impact 2021 (in millions) Americas $ 2,617.1 $ 9.3 $ 2,626.4 International 867.1 9.0 876.1 Total $ 3,484.2 $ 18.3 $ 3,502.5
Schedule of finite-lived intangible assets by major class	September 30, 2021 September 30, 2020 Gross Accumulated Intangible Gross Accumulated Intangible Amortization Amount Amortization Assets, Net Amount Amortization Assets, Net Period (in millions) (years) Backlog and customer relationships $ 663.4 $ (608.5) $ 54.9 $ 662.8 $ (585.9) $ 76.9 1 - 11
Schedule of estimated future amortization expense of intangible assets	Fiscal Year (in millions) 2022 $ 18.6 2023 18.2 2024 17.4 2025 0.7 Total $ 54.9

Revenue Recognition (Tables)

Revenue Recognition (Tables)	12 Months Ended
Revenue Recognition (Tables)	Sep. 30, 2021
Revenue Recognition
Schedule of revenues disaggregated by revenue sources	Fiscal Year Ended September 30, September 30, September 30, 2021 2020 2019 (in millions) Cost reimbursable $ 5,319.4 $ 5,734.5 $ 5,958.2 Guaranteed maximum price 4,582.7 3,896.8 3,962.6 Fixed price 3,438.8 3,608.7 3,721.7 Total revenue $ 13,340.9 $ 13,240.0 $ 13,642.5 Fiscal Year Ended September 30, September 30, September 30, 2021 2020 2019 (in millions) Americas $ 10,228.3 $ 10,138.3 $ 10,390.8 Europe, Middle East, Africa 1,588.1 1,620.3 1,752.1 Asia Pacific 1,524.5 1,481.4 1,499.6 Total revenue $ 13,340.9 $ 13,240.0 $ 13,642.5
Schedule of net accounts receivable	Fiscal Year Ended September 30, September 30, 2021 2020 (in millions) Billed $ 2,181.1 $ 2,467.3 Contract retentions 531.2 531.3 Total accounts receivable—gross 2,712.3 2,998.6 Allowance for doubtful accounts and credit losses (92.8) (77.9) Total accounts receivable—net $ 2,619.5 $ 2,920.7

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
Property and Equipment (Tables)	Sep. 30, 2021
Property and Equipment
Schedule of property and equipment, at cost	Fiscal Year Ended September 30, September 30, Useful Lives 2021 2020 (years) (in millions) Building and land $ 14.4 $ 11.5 10 - 45 Leasehold improvements 351.2 343.2 1 - 20 Computer systems and equipment 602.1 557.4 3 - 12 Furniture and fixtures 112.7 134.8 3 - 10 Total 1,080.4 1,046.9 Accumulated depreciation and amortization (681.5) (665.2) Property and equipment, net $ 398.9 $ 381.7

Joint Ventures and Variable I_2

Joint Ventures and Variable Interest Entities (Tables)	12 Months Ended
Joint Ventures and Variable Interest Entities (Tables)	Sep. 30, 2021
Joint Ventures and Variable Interest Entities
Summary of financial information of the consolidated joint ventures	September 30, September 30, 2021 2020 (in millions) Current assets $ 503.9 $ 536.3 Non-current assets 74.8 77.0 Total assets $ 578.7 $ 613.3 Current liabilities $ 400.3 $ 409.9 Non-current liabilities 1.5 1.5 Total liabilities 401.8 411.4 Total AECOM equity 74.0 113.9 Noncontrolling interests 102.9 88.0 Total owners’ equity 176.9 201.9 Total liabilities and owners’ equity $ 578.7 $ 613.3
Summary of financial information of the unconsolidated joint ventures, as derived from their unaudited financial statements	September 30, September 30, 2021 2020 (in millions) Current assets $ 1,323.2 $ 1,374.3 Non-current assets 1,001.6 465.8 Total assets $ 2,324.8 $ 1,840.2 Current liabilities $ 845.8 $ 953.4 Non-current liabilities 537.2 58.9 Total liabilities 1,383.0 1,012.3 Joint ventures’ equity 941.8 827.9 Total liabilities and joint ventures’ equity $ 2,324.8 $ 1,840.2 AECOM’s investment in joint ventures $ 328.9 $ 297.6 Twelve Months Ended September 30, September 30, 2021 2020 (in millions) Revenue $ 2,096.5 $ 3,058.9 Cost of revenue 2,051.2 2,993.1 Gross profit $ 45.3 $ 65.8 Net income $ 37.0 $ 59.8
Summary of AECOM's equity in earnings of unconsolidated joint ventures	Fiscal Year Ended September 30, September 30, September 30, 2021 2020 2019 (in millions) Pass through joint ventures $ 23.6 $ 34.1 $ 31.6 Other joint ventures 11.4 14.7 17.7 Total $ 35.0 $ 48.8 $ 49.3

Pension Benefit Obligations (Ta

Pension Benefit Obligations (Tables)	12 Months Ended
Pension Benefit Obligations (Tables)	Sep. 30, 2021
Pension Benefit Obligations
Reconciliations of the changes in the U.S. and international plans' benefit obligations	Fiscal Year Ended September 30, September 30, September 30, 2021 2020 2019 U.S. Int’l U.S. Int’l U.S. Int’l (in millions) Change in benefit obligation: Benefit obligation at beginning of year $ 283.9 $ 1,440.3 $ 275.6 $ 1,311.3 $ 257.1 $ 1,188.8 Service cost — 0.5 — 0.6 — 0.5 Participant contributions 0.1 0.3 — 0.3 0.1 0.3 Interest cost 4.3 21.6 6.8 22.4 9.5 29.7 Benefits and expenses paid (18.5) (48.6) (18.4) (42.9) (17.6) (41.3) Actuarial (gain) loss (3.7) (4.7) 22.0 82.8 27.8 206.5 Plan settlements (0.7) (5.9) (2.1) (4.1) (1.3) (3.7) Plan amendments — 0.4 — — — 5.2 Foreign currency translation (gain) loss — 66.9 — 69.9 — (74.7) Benefit obligation at end of year $ 265.4 $ 1,470.8 $ 283.9 $ 1,440.3 $ 275.6 $ 1,311.3
Reconciliations of the changes in the fair value of assets	Fiscal Year Ended September 30, September 30, September 30, 2021 2020 2019 U.S. Int’l U.S. Int’l U.S. Int’l (in millions) Change in plan assets Fair value of plan assets at beginning of year $ 129.6 $ 1,166.2 $ 129.3 $ 1,068.8 $ 131.4 $ 965.9 Actual return on plan assets 14.7 61.1 11.7 59.5 4.5 180.3 Employer contributions 13.7 25.2 9.1 27.7 12.2 28.2 Participant contributions 0.1 0.3 — 0.3 0.1 0.3 Benefits and expenses paid (18.5) (48.6) (18.4) (42.9) (17.6) (41.3) Plan settlements (0.7) (5.9) (2.1) (4.1) (1.3) (3.7) Foreign currency translation gain (loss) — 53.5 — 56.9 — (60.9) Fair value of plan assets at end of year $ 138.9 $ 1,251.8 $ 129.6 $ 1,166.2 $ 129.3 $ 1,068.8
Reconciliations of the funded status	Fiscal Year Ended September 30, 2021 September 30, 2020 September 30, 2019 U.S. Int’l U.S. Int’l U.S. Int’l (in millions) Reconciliation of funded status: Funded status at end of year $ (126.5) $ (219.0) $ (154.3) $ (274.1) $ (146.3) $ (242.5) Contribution made after measurement date N/A N/A N/A N/A N/A N/A Net amount recognized at end of year $ (126.5) $ (219.0) $ (154.3) $ (274.1) $ (146.3) $ (242.5)
Amounts recognized in the consolidated balance sheets	Fiscal Year Ended September 30, 2021 September 30, 2020 September 30, 2019 U.S. Int’l U.S. Int’l U.S. Int’l (in millions) Amounts recognized in the consolidated balance sheets: Other non-current assets $ — $ 47.5 $ — $ 44.0 $ — $ 28.3 Accrued expenses and other current liabilities (9.1) — (9.4) — (9.0) — Pension benefit obligations (117.4) (266.5) (144.9) (318.1) (137.3) (270.8) Net amount recognized in the balance sheet $ (126.5) $ (219.0) $ (154.3) $ (274.1) $ (146.3) $ (242.5)
Reconciliation of amounts in the consolidated statements of stockholder's equity	Fiscal Year Ended September 30, 2021 September 30, 2020 September 30, 2019 U.S. Int’l U.S. Int’l U.S. Int’l (in millions) Reconciliation of amounts in consolidated statements of stockholders’ equity: Prior service (cost) credit $ (0.1) $ (1.6) $ (0.1) $ (1.2) $ (0.7) $ (1.2) Net loss (116.5) (279.5) (134.5) (297.7) (122.4) (233.0) Total recognized in accumulated other comprehensive loss $ (116.6) $ (281.1) $ (134.6) $ (298.9) $ (123.1) $ (234.2)
Components of net periodic cost for the Company's pension and post-retirement plans	Fiscal Year Ended September 30, 2021 September 30, 2020 September 30, 2019 U.S. Int’l U.S. Int’l U.S. Int’l (in millions) Components of net periodic benefit cost: Service costs $ — $ 0.5 $ — $ 0.6 $ — $ 0.5 Interest cost on projected benefit obligation 4.3 21.6 6.8 22.4 9.5 29.7 Expected return on plan assets (6.5) (43.5) (7.0) (37.5) (9.0) (38.1) Amortization of prior service costs (credits) — 0.1 0.1 0.1 0.1 (0.1) Amortization of net loss 5.9 9.2 4.7 8.6 3.7 4.1 Curtailment loss recognized — — 0.5 — — — Settlement loss recognized 0.2 0.8 0.6 0.5 0.2 0.8 Net periodic benefit cost $ 3.9 $ (11.3) $ 5.7 $ (5.3) $ 4.5 $ (3.1)
Amounts included in accumulated other comprehensive loss that are expected to be recognized as components of net periodic benefit cost during the next fiscal year	U.S. Int’l Amortization of prior service cost $ — $ (0.1) Amortization of net actuarial losses (5.6) (7.4) Total $ (5.6) $ (7.5)
Additional year-end information for pension plans with accumulated benefit obligations in excess of plan assets	Fiscal Year Ended September 30, September 30, September 30, 2021 2020 2019 U.S. Int’l U.S. Int’l U.S. Int’l (in millions) Projected benefit obligation $ 247.8 $ 1,248.8 $ 265.1 $ 1,216.6 $ 257.3 $ 1,141.9 Accumulated benefit obligation 247.8 1,243.9 265.1 1,211.5 257.3 1,132.7 Fair value of plan assets 138.9 982.4 129.6 898.5 129.3 871.2
Schedule of expected future benefit payments	Year Ending September 30, U.S. Int’l 2022 $ 21.0 $ 58.6 2023 21.4 57.4 2024 20.0 58.6 2025 19.7 60.1 2026 19.6 61.9 2027-2031 83.6 339.1 Total $ 185.3 $ 635.7
Schedule of underlying assumptions for the pension plans	Fiscal Year Ended September 30, September 30, September 30, 2021 2020 2019 U.S. Int’l U.S. Int’l U.S. Int’l (in millions) Weighted-average assumptions to determine benefit obligation: Discount rate 2.46 % 1.98 % 2.20 % 1.67 % 2.92 % 1.81 % Salary increase rate N/A 3.13 % N/A 2.68 % N/A 2.52 % Weighted-average assumptions to determine net periodic benefit cost: Discount rate 2.20 % 1.67 % 2.92 % 1.81 % 4.10 % 2.91 % Salary increase rate N/A 2.68 % N/A 2.52 % N/A 2.79 % Expected long-term rate of return on plan assets 6.80 % 3.95 % 7.30 % 4.03 % 7.00 % 4.43 %
Summary of the Company's target allocation and pension plan asset allocation, both U.S. and international	Percentage of Plan Assets as of September 30, Target Allocations 2021 2020 U.S. Int’l U.S. Int’l U.S. Int’l Asset Category: Equities 40 % 34 % 41 % 34 % 47 % 26 % Debt 48 54 44 53 42 54 Cash 2 2 5 3 1 4 Property and other 10 10 10 10 10 16 Total 100 % 100 % 100 % 100 % 100 % 100 %
Fair values of the Company's post retirement benefit plan assets by major asset categories	Fair Value Measurement as of September 30, 2021 Total Quoted Significant Carrying Prices in Other Significant Value as of Active Observable Unobservable Investments September 30, Markets Inputs Inputs measured at 2021 (Level 1) (Level 2) (Level 3) NAV (in millions) Cash and cash equivalents $ 49.8 $ 25.1 $ 24.7 $ — $ — Equity and debt securities 488.5 488.5 — — — Investment funds: Diversified and equity funds 81.2 60.5 16.7 4.0 — Fixed income funds 29.3 25.0 4.3 — — Common collective funds 734.8 — — — 734.8 Derivative instruments 7.1 — 7.1 — — Total $ 1,390.7 $ 599.1 $ 52.8 $ 4.0 $ 734.8 Fair Value Measurement as of September 30, 2020 Total Quoted Significant Carrying Prices in Other Significant Value as of Active Observable Unobservable Investments September 30, Markets Inputs Inputs measured at 2020 (Level 1) (Level 2) (Level 3) NAV (in millions) Cash and cash equivalents $ 50.6 $ 20.2 $ 30.4 $ — $ — Equity and debt securities 442.3 442.3 — — — Investment funds: Diversified and equity funds 31.5 13.0 15.1 3.4 — Fixed income funds 36.2 23.1 13.1 — — Common collective funds 707.5 — — — 707.5 Derivative instruments 27.7 — 27.7 — — Total $ 1,295.8 $ 498.6 $ 86.3 $ 3.4 $ 707.5
Changes in the fair value of the Company's post-retirement plan Level 3 assets	Actual return Actual return on plan assets, on plan assets, Change September 30, relating to relating to Transfer due to 2020 assets still assets sold Purchases, into / exchange September 30, Beginning held at during the sales and (out of) rate 2021 balance reporting date period settlements Level 3 changes Ending balance (in millions) Level 3 Assets $ 3.4 $ 0.4 $ — $ 0.2 $ — $ — $ 4.0 Actual return Actual return on plan assets, on plan assets, Change September 30, relating to relating to Transfer due to 2019 assets still assets sold Purchases, into / exchange September 30, Beginning held at during the sales and (out of) rate 2020 balance reporting date period settlements Level 3 changes Ending balance (in millions) Level 3 Assets $ 26.8 $ (0.2) $ (2.1) $ (25.4) $ 3.2 $ 1.1 $ 3.4

Debt (Tables)

Debt (Tables)	12 Months Ended
Debt (Tables)	Sep. 30, 2021
Debt
Schedule of debt	September 30, September 30, 2021 2020 (in millions) Credit Agreement $ 1,155.3 $ 248.5 2024 Senior Notes — 797.3 2027 Senior Notes 997.3 997.3 Other debt 83.0 41.9 Total debt 2,235.6 2,085.0 Less: Current portion of debt and short-term borrowings (53.8) (20.9) Less: Unamortized debt issuance costs (24.1) (23.0) Long-term debt $ 2,157.7 $ 2,041.1
Schedule of maturities of debt	The following table presents, in millions, scheduled maturities of the Company’s debt as of September 30, 2021: Fiscal Year 2022 $ 53.8 2023 45.9 2024 41.0 2025 35.1 2026 400.4 Thereafter 1,659.4 Total $ 2,235.6

Derivative Financial Instrume_2

Derivative Financial Instruments and Fair Value Measurements (Tables)	12 Months Ended
	Sep. 30, 2021
Derivative Financial Instruments and Fair Value Measurements
Notional principle, fixed rates and related expiration dates of outstanding interest rate swap agreements	September 30, 2021 Notional Amount Notional Amount Fixed Effective Expiration Currency (in millions) Rate Date Date USD 200.0 2.60 % March 2018 February 2023 USD 400.0 1.349 % February 2023 March 2028 September 30, 2020 Notional Amount Notional Amount Fixed Effective Expiration Currency (in millions) Rate Date Date USD 200.0 2.60 % March 2018 February 2023

Leases (Tables)

Leases (Tables)	12 Months Ended
Leases (Tables)	Sep. 30, 2021
Leases
Schedule of components of lease expense	Fiscal Year Ended September 30, 2021 September 30, 2020 (in millions) Operating lease cost $ 186.5 $ 191.6 Finance lease cost: Amortization of right-of-use assets 13.0 17.1 Interest on lease liabilities 2.0 1.9 Variable lease cost 35.5 36.5 Total lease cost $ 237.0 $ 247.1
Schedule of additional balance sheet information related to leases	As of (in millions except as noted) Balance Sheet Classification September 30, 2021 September 30, 2020 Assets: Operating lease assets Operating lease right-of-use assets $ 607.1 $ 652.1 Finance lease assets Property and equipment – net 44.4 29.1 Total lease assets $ 651.5 $ 681.2 Liabilities: Current: Operating lease liabilities Accrued expenses and other current liabilities $ 157.3 $ 168.4 Finance lease liabilities Current portion of long-term debt 13.4 9.8 Total current lease liabilities 170.7 178.2 Non-current: Operating lease liabilities Operating lease liabilities, noncurrent 679.1 745.3 Finance lease liabilities Long-term debt 32.1 22.0 Total non-current lease liabilities $ 711.2 $ 767.3 As of September 30, 2021 September 30, 2020 Weighted average remaining lease term (in years): Operating leases 6.9 7.3 Finance leases 3.5 3.3 Weighted average discount rates: Operating leases 4.3 % 4.6 % Finance leases 4.3 % 4.7 %
Schedule of additional cash flow information related to leases	Fiscal Year Ended September 30, September 30, 2021 2020 (in millions) Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 221.4 $ 208.7 Operating cash flows from finance leases 2.0 1.8 Financing cash flows from finance leases 13.7 14.7 Right-of-use assets obtained in exchange for new operating leases 102.7 126.9 Right-of-use assets obtained in exchange for new finance leases 28.5 26.4
Schedule of total remaining lease payments under the Company's operating and finance leases	Operating Leases Finance Leases Fiscal Year (in millions) 2022 $ 190.0 $ 15.2 2023 156.2 14.9 2024 134.7 11.7 2025 114.9 5.8 2026 91.6 1.5 Thereafter 286.8 — Total lease payments $ 974.2 $ 49.1 Less: Amounts representing interest $ (137.8) $ (3.6) Total lease liabilities $ 836.4 $ 45.5

Share-based Payments (Tables)

Share-based Payments (Tables)	12 Months Ended
Share-based Payments (Tables)	Sep. 30, 2021
Share-based Payments
Schedule of stock option activity	Number of Weighted Options Average (in millions) Exercise Price Balance, September 30, 2018 0.6 31.62 Granted — — Exercised — — Cancelled (0.5) (31.62) Balance, September 30, 2019 0.1 31.62 Granted 0.3 38.72 Exercised — — Cancelled — — Balance, September 30, 2020 0.4 36.41 Granted — — Exercised (0.1) 31.62 Cancelled — — Balance, September 30, 2021 0.3 38.72 Exercisable as of September 30, 2019 0.1 31.62 Exercisable as of September 30, 2020 0.1 31.62 Exercisable as of September 30, 2021 — —

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
Income Taxes (Tables)	Sep. 30, 2021
Income Taxes
Schedule of income tax (benefit) expense	Fiscal Year Ended September 30, September 30, September 30, 2021 2020 2019 (in millions) Current: Federal $ 32.2 $ 21.8 $ (17.3) State 6.8 12.7 29.8 Foreign 53.2 55.7 41.7 Total current income tax expense 92.2 90.2 54.2 Deferred: Federal (28.8) (21.8) (26.1) State 18.8 12.8 (24.6) Foreign 6.8 (35.4) 10.0 Total deferred income tax benefit (3.2) (44.4) (40.7) Total income tax expense $ 89.0 $ 45.8 $ 13.5
Major elements contributing to the difference between the U.S. federal statutory rate of 24.5% for fiscal year 2018 and 35% for fiscal years ended 2017 and 2016 and the effective tax rate	Fiscal Year Ended September 30, September 30, September 30, 2021 2020 2019 Amount % Amount % Amount % (in millions) Tax at federal statutory rate $ 85.8 21.0 % $ 48.8 21.0 % $ 52.0 21.0 % State income tax, net of federal benefit 8.0 2.0 8.4 3.6 7.0 2.8 Foreign residual income 45.6 11.1 39.5 17.0 35.8 14.5 Valuation allowance 12.4 3.0 (15.9) (6.9) (26.5) (10.7) Audit settlement 10.4 2.5 — — (4.6) (1.9) Foreign tax rate differential 8.8 2.1 3.2 1.4 (3.1) (1.3) Change in uncertain tax positions 8.5 2.1 (8.3) (3.6) 5.6 2.3 Nondeductible costs 6.0 1.5 15.8 6.8 7.6 3.1 Income tax credits and incentives (51.3) (12.5) (47.8) (20.6) (44.7) (18.1) Tax rate changes (26.8) (6.5) (0.5) (0.2) (1.9) (0.8) Return to provision (9.5) (2.3) 5.1 2.2 (0.2) (0.1) Exclusion of tax on non-controlling interests (6.1) (1.5) (3.4) (1.5) (5.3) (2.1) Tax exempt income (5.4) (1.3) (5.1) (2.2) (3.9) (1.6) Other items, net 2.6 0.6 6.0 2.7 (4.3) (1.7) Total income tax expense $ 89.0 21.8 % $ 45.8 19.7 % $ 13.5 5.4 %
Schedule of deferred tax assets (liabilities)	Fiscal Year Ended September 30, September 30, 2021 2020 (in millions) Deferred tax assets: Compensation and benefit accruals not currently deductible $ 130.0 $ 119.4 Net operating loss carryforwards 169.8 173.2 Self-insurance reserves 12.3 17.6 Research and experimentation and other tax credits 117.2 112.9 Pension liability 87.7 95.1 Accrued liabilities 284.7 307.6 Capital loss carryforward 62.0 104.8 Other 37.3 26.0 Total deferred tax assets 901.0 956.6 Deferred tax liabilities: Unearned revenue (19.8) (40.3) Depreciation and amortization (116.5) (106.7) Acquired intangible assets (19.4) (24.5) Investment in subsidiaries (13.4) (10.9) Right of use assets (145.6) (164.9) Contingent consideration (33.8) (33.6) Total deferred tax liabilities (348.5) (380.9) Valuation allowance (197.7) (217.5) Net deferred tax assets $ 354.8 $ 358.2
Reconciliation of the beginning and ending amount of gross unrecognized tax benefits	Fiscal Year Ended September 30, September 30, 2021 2020 (in millions) Balance at the beginning of the year $ 47.1 $ 55.7 Gross increase in current period’s tax positions 4.3 2.8 Gross increase in prior years’ tax positions 7.5 — Gross decrease in prior years’ tax positions — (7.9) Decrease due to settlement with tax authorities (1.3) (0.5) Decrease due to lapse of statute of limitations — (3.5) Gross change due to foreign exchange fluctuations (11.2) 0.5 Balance at the end of the year $ 46.4 $ 47.1

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
Earnings Per Share (Tables)	Sep. 30, 2021
Earnings Per Share
Reconciliation of the denominators for basic and diluted EPS	Fiscal Year Ended September 30, September 30, September 30, 2021 2020 2019 (in millions) Denominator for basic earnings per share 147.3 159.0 157.0 Potential common shares 2.4 2.3 2.7 Denominator for diluted earnings per share 149.7 161.3 159.7

Other Financial Information (Ta

Other Financial Information (Tables)	12 Months Ended
Other Financial Information (Tables)	Sep. 30, 2021
Other Financial Information
Schedule of accrued expenses and other current liabilities	Fiscal Year Ended September 30, September 30, 2021 2020 (in millions) Accrued salaries and benefits $ 661.8 $ 675.7 Accrued contract costs 1,202.1 1,137.5 Other accrued expenses 310.3 436.5 $ 2,174.2 $ 2,249.7

Reclassifications out of Accu_2

Reclassifications out of Accumulated Other Comprehensive Loss (Tables)	12 Months Ended
	Sep. 30, 2021
Reclassifications out of Accumulated Other Comprehensive Loss
Schedule of accumulated balances and reporting period activities related to reclassifications out of accumulated other comprehensive loss	Foreign Accumulated Pension Currency Loss on Other Related Translation Derivative Comprehensive Adjustments Adjustments Instruments Loss Balances at September 30, 2018 $ (202.3) $ (502.2) $ 1.2 $ (703.3) Other comprehensive income (loss) before reclassification (107.2) (46.5) (17.2) (170.9) Amounts reclassified from accumulated other comprehensive loss 6.8 — 3.2 10.0 Balances at September 30, 2019 $ (302.7) $ (548.7) $ (12.8) $ (864.2) Foreign Accumulated Pension Currency Loss on Other Related Translation Derivative Comprehensive Adjustments Adjustments Instruments Loss Balances at September 30, 2019 $ (302.7) $ (548.7) $ (12.8) $ (864.2) Other comprehensive income (loss) before reclassification (72.5) (18.6) (5.3) (96.4) Amounts reclassified from accumulated other comprehensive loss 32.4 — 9.5 41.9 Balances at September 30, 2020 $ (342.8) $ (567.3) $ (8.6) $ (918.7) Foreign Accumulated Pension Currency Loss on Other Related Translation Derivative Comprehensive Adjustments Adjustments Instruments Loss Balances at September 30, 2020 $ (342.8) $ (567.3) $ (8.6) $ (918.7) Other comprehensive income (loss) before reclassification 14.6 (12.8) 0.8 2.6 Amounts reclassified from accumulated other comprehensive loss 12.0 — 3.7 15.7 Balances at September 30, 2021 $ (316.2) $ (580.1) $ (4.1) $ (900.4)

Reportable Segments and Geogr_2

Reportable Segments and Geographic Information (Tables)	12 Months Ended
Reportable Segments and Geographic Information (Tables)	Sep. 30, 2021
Reportable Segments and Geographic Information
Summarized financial information concerning the Company's reportable segments	AECOM Reportable Segments: Americas International Capital Corporate Total (in millions) Fiscal Year Ended September 30, 2021: Revenue $ 10,226.3 $ 3,112.6 $ 2.0 $ — $ 13,340.9 Gross profit 631.6 164.8 2.0 — 798.4 Equity in earnings of joint ventures 11.4 12.2 11.4 — 35.0 General and administrative expenses — — (11.1) (143.9) (155.0) Restructuring costs — — — (48.8) (48.8) Operating income 643.0 177.0 2.3 (192.7) 629.6 Segment assets 7,204.6 2,764.5 234.6 1,390.9 Gross profit as a % of revenue 6.2 % 5.3 % 6.0 % Fiscal Year Ended September 30, 2020: Revenue $ 10,131.5 $ 3,101.7 $ 6.8 $ — $ 13,240.0 Gross profit 580.5 122.2 6.9 — 709.6 Equity in earnings of joint ventures 19.8 14.3 14.7 — 48.8 General and administrative expenses — — (8.6) (180.0) (188.6) Restructuring costs — — — (188.3) (188.3) Operating income 600.3 136.5 13.0 (368.3) 381.5 Segment assets 8,104.4 2,454.0 198.0 1,625.8 Gross profit as a % of revenue 5.7 % 3.9 % 5.4 % Fiscal Year Ended September 30, 2019: Revenue $ 10,382.6 $ 3,251.7 $ 8.2 $ — $ 13,642.5 Gross profit 511.5 91.9 8.3 — 611.7 Equity in earnings of joint ventures 17.7 13.9 17.7 — 49.3 General and administrative expenses — — (5.0) (143.2) (148.2) Restructuring costs — — — (95.4) (95.4) Gain on disposal activities — 3.6 — — 3.6 Impairment of long lived assets (10.8) (4.4) — (9.7) (24.9) Operating income 518.4 105.0 21.0 (248.3) 396.1 Segment assets 7,437.3 2,247.1 197.8 718.4 Gross profit as a % of revenue 4.9 % 2.8 % 4.5 %
Schedule of Geographic Information	Fiscal Year Ended September 30, September 30, September 30, Long-Lived Assets 2021 2020 2019 (in millions) Americas 3,922.8 3,733.2 3,399.1 Europe, Middle East, Africa 872.3 875.8 738.8 Asia Pacific 405.0 375.3 272.4 Total 5,200.1 4,984.3 4,410.3

Quarterly Financial Informati_2

Quarterly Financial Information - Unaudited (Tables)	12 Months Ended
Quarterly Financial Information - Unaudited (Tables)	Sep. 30, 2021
Quarterly Financial Information-Unaudited
Schedule of unaudited quarterly data	First Second Third Fourth Fiscal Year 2021: Quarter Quarter Quarter Quarter (in millions, except per share data) Revenue $ 3,313.2 $ 3,265.5 $ 3,408.4 $ 3,353.8 Cost of revenue 3,128.8 3,070.3 3,206.8 3,136.6 Gross profit 184.4 195.2 201.6 217.2 Equity in earnings of joint ventures 8.2 7.2 8.2 11.4 General and administrative expenses (38.4) (36.0) (36.3) (44.3) Restructuring costs (13.0) (8.8) (13.0) (14.0) Income from operations 141.2 157.6 160.5 170.3 Other income 3.9 3.5 4.5 5.7 Interest expense (30.7) (32.8) (149.0) (25.9) Income from continuing operations before taxes 114.4 128.3 16.0 150.1 Income tax expense (benefit) for continuing operations 25.6 35.1 (17.8) 46.1 Net income from continuing operations 88.8 93.2 33.8 104.0 Net loss from discontinued operations (55.8) (47.9) (15.4) 2.3 Net income 33.0 45.3 18.4 106.3 Net income attributable to noncontrolling interests from continuing operations (5.4) (4.9) (5.9) (8.9) Net income attributable to noncontrolling interests from discontinued operations (1.5) (1.0) (1.0) (1.2) Net income attributable to noncontrolling interests (6.9) (5.9) (6.9) (10.1) Net income attributable to AECOM from continuing operations 83.4 88.3 27.9 95.1 Net loss attributable to AECOM from discontinued operations (57.3) (48.9) (16.4) 1.1 Net income attributable to AECOM $ 26.1 $ 39.4 $ 11.5 $ 96.2 Net income (loss) attributable to AECOM per share: Basic continuing operations per share $ 0.55 $ 0.60 $ 0.19 $ 0.66 Basic discontinued operations per share $ (0.38) $ (0.33) $ (0.11) $ 0.01 Basic earnings per share $ 0.17 $ 0.27 $ 0.08 $ 0.67 Diluted continuing operations per share $ 0.54 $ 0.59 $ 0.19 $ 0.65 Diluted discontinued operations per share $ (0.37) $ (0.33) $ (0.11) $ 0.01 Diluted earnings per share $ 0.17 $ 0.26 $ 0.08 $ 0.66 Weighted average shares outstanding: Basic 151.4 147.8 146.1 143.8 Diluted 153.7 149.5 148.9 146.6 First Second Third Fourth Fiscal Year 2020: Quarter Quarter Quarter Quarter (in millions, except per share data) Revenue $ 3,235.6 $ 3,245.7 $ 3,189.7 $ 3,569.0 Cost of revenue 3,069.8 3,076.9 3,004.6 3,379.1 Gross profit 165.8 168.8 185.1 189.9 Equity in earnings of joint ventures 9.9 13.5 8.6 16.8 General and administrative expenses (43.6) (41.0) (54.5) (49.5) Restructuring costs (44.9) (31.2) (20.3) (91.9) Income from operations 87.2 110.1 118.9 65.3 Other income 4.0 2.4 3.1 1.6 Interest expense (40.4) (37.1) (35.0) (47.5) Income from continuing operations before taxes 50.8 75.4 87.0 19.4 Income tax expense (benefit) for continuing operations 15.9 21.7 (7.2) 15.3 Net income from continuing operations 34.9 53.7 94.2 4.1 Net income (loss) from discontinued operations 18.2 (130.7) (0.1) (228.0) Net income (loss) 53.1 (77.0) 94.1 (223.9) Net income attributable to noncontrolling interests from continuing operations (4.0) (5.2) (3.1) (4.2) Net income attributable to noncontrolling interests from discontinued operations (8.5) (3.9) (1.6) (2.2) Net income attributable to noncontrolling interests (12.5) (9.1) (4.7) (6.4) Net income (loss) attributable to AECOM from continuing operations 30.9 48.5 91.1 (0.1) Net income (loss) attributable to AECOM from discontinued operations 9.7 (134.6) (1.7) (230.2) Net income (loss) attributable to AECOM $ 40.6 $ (86.1) $ 89.4 $ (230.3) Net income attributable to AECOM per share: Basic continuing operations per share $ 0.20 $ 0.31 $ 0.57 $ — Basic discontinued operations per share $ 0.06 $ (0.85) $ (0.01) $ (1.44) Basic earnings per share $ 0.26 $ (0.54) $ 0.56 $ (1.44) Diluted continuing operations per share $ 0.19 $ 0.30 $ 0.56 $ — Diluted discontinued operations per share $ 0.06 $ (0.84) $ (0.01) $ (1.44) Diluted earnings per share $ 0.25 $ (0.54) $ 0.55 $ (1.44) Weighted average shares outstanding: Basic 157.3 158.6 160.1 160.0 Diluted 160.6 160.7 161.8 160.0

Significant Accounting Polici_3

Significant Accounting Policies - Fiscal Year (Details)	12 Months Ended
Significant Accounting Policies - Fiscal Year (Details)	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Length of fiscal year	364 days	371 days	364 days
Minimum
Length of fiscal year	364 days
Maximum
Length of fiscal year	371 days

Significant Accounting Polici_4

Significant Accounting Policies - Property and Equipment (Details)	12 Months Ended
	Sep. 30, 2021
Minimum \| Building and land
Property, Plant and Equipment
Estimated useful live (in years)	10 years
Minimum \| Furniture and fixtures
Property, Plant and Equipment
Estimated useful live (in years)	3 years
Minimum \| Computer systems and equipment
Property, Plant and Equipment
Estimated useful live (in years)	3 years
Maximum \| Building and land
Property, Plant and Equipment
Estimated useful live (in years)	45 years
Maximum \| Furniture and fixtures
Property, Plant and Equipment
Estimated useful live (in years)	10 years
Maximum \| Computer systems and equipment
Property, Plant and Equipment
Estimated useful live (in years)	12 years

Significant Accounting Polici_5

Significant Accounting Policies - Pension Plans (Details)	12 Months Ended
Significant Accounting Policies - Pension Plans (Details)	Sep. 30, 2021
Significant Accounting Policies
Market-related valuation calculation period (in years)	5 years
Net unrecognized gain (loss) threshold subject to amortization (in percent)	10.00%

New Accounting Pronouncements_2

New Accounting Pronouncements and Changes in Accounting (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Oct. 01, 2020	Sep. 30, 2020	Oct. 01, 2019
New Accounting Pronouncements and Changes in Accounting
(Accumulated deficits) / Retained earnings	$ (504,126)		$ 174,248
ASU 2016-02
New Accounting Pronouncements and Changes in Accounting
(Accumulated deficits) / Retained earnings				$ 87,800
ASU 2016-06
New Accounting Pronouncements and Changes in Accounting
(Accumulated deficits) / Retained earnings		$ 8,000

Discontinued Operations, Good_3

Discontinued Operations, Goodwill, and Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended			12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2021	Sep. 30, 2020
Summary of financial information of the Disposal Group
Asset Impairment Charges				$ 24,900
Impairment			$ 83,600
Impairment of Intangible Assets (Excluding Goodwill)			5,700
Summary of financial information of the Disposal Group is as follows:
Write-down of assets to fair value less cost to sell						$ 247,200
Non-current assets held for sale						54,354
Long-term liabilities held for sale					$ 11,095	79,254
Management Services
Summary of financial information of the Disposal Group
Consideration			2,280,000
Favorable working capital price adjustment			122,000
Contingent consideration, prior work claims			$ 120,000
Held for sale
Summary of financial information of the Disposal Group is as follows:
Cash and cash equivalents					5,600	109,900
Receivables and contract assets					90,300	414,300
Other					43,500	38,200
Current assets held for sale					139,400	562,400
Property and equipment, net					52,900	119,800
Other					18,500	181,800
Write-down of assets to fair value less cost to sell					(71,400)	(247,200)
Non-current assets held for sale						54,400
Accounts payable and accrued expenses					88,500	350,400
Contract liabilities						65,600
Other					5,500	1,600
Current liabilities held for sale					94,000	417,600
Long-term liabilities held for sale					$ 11,100	$ 79,300
Held for sale \| Power construction business
Summary of financial information of the Disposal Group
Pre-tax gain (loss)		$ 17,300
Held for sale \| Civil infrastructure construction business
Summary of financial information of the Disposal Group
Losses on remeasurement to fair value less cost to sell, net of tax	$ 32,800

Discontinued Operations, Good_4

Discontinued Operations, Goodwill, and Intangible Assets - Income Statement Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Summary of financial information of the Disposal Group
(Loss) gain on disposal activities									$ (52,532)	$ 161,900
Impairment of long-lived assets, including goodwill									(105,194)	(336,472)	$ (615,400)
Net loss from discontinued operations	$ 2,300	$ (15,400)	$ (47,900)	$ (55,800)	$ (228,000)	$ (100)	$ (130,700)	$ 18,200	(116,813)	(340,591)	$ (419,662)
Held for sale
Summary of financial information of the Disposal Group
Revenue									771,500	3,150,800
Cost of revenue									760,500	3,179,200
Gross (loss) profit									11,000	(28,400)
Equity in earnings of joint ventures									4,000	(25,500)
(Loss) gain on disposal activities									(52,500)	161,900
Transaction costs									(15,300)	(43,200)
Impairment of long-lived assets, including goodwill									(105,200)	(336,500)
Loss from operations									(158,000)	(271,700)
Other income										1,800
Interest expense									(500)	(40,500)
Loss before taxes									(158,500)	(310,400)
Income tax (benefit) expense									(41,700)	30,200
Net loss from discontinued operations									$ (116,800)	$ (340,600)

Discontinued Operations, Good_5

Discontinued Operations, Goodwill, and Intangible Assets - Significant components included in Consolidated Statement of Cash Flows (Details) - Held for sale - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Summary of financial information of the Disposal Group
Property and equipment		$ 4.6
Intangible assets and capitalized debt issuance costs		26
Payments for capital expenditures	$ (7.3)	$ (19.6)

Discontinued Operations, Good_6

Discontinued Operations, Goodwill, and Intangible Assets - Segments (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2021USD ($)
Changes in the carrying value of goodwill by reporting segment
Goodwill at the beginning of the period	$ 3,484,221
Foreign Exchange Impact	18,300
Goodwill at the end of the period	3,502,499
Americas
Changes in the carrying value of goodwill by reporting segment
Goodwill at the beginning of the period	2,617,100
Foreign Exchange Impact	9,300
Goodwill at the end of the period	2,626,400
International
Changes in the carrying value of goodwill by reporting segment
Goodwill at the beginning of the period	867,100
Foreign Exchange Impact	9,000
Goodwill at the end of the period	$ 876,100

Discontinued Operations, Good_7

Discontinued Operations, Goodwill, and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Identifiable intangible assets with finite useful lives
Intangible Assets, Net	$ 54,867	$ 76,917
Backlog and customer relationships
Identifiable intangible assets with finite useful lives
Gross Amount	663,400	662,800
Accumulated Amortization	(608,500)	(585,900)
Intangible Assets, Net	$ 54,900	$ 76,900
Backlog and customer relationships \| Minimum
Identifiable intangible assets with finite useful lives
Amortization Period	1 year
Backlog and customer relationships \| Maximum
Identifiable intangible assets with finite useful lives
Amortization Period	11 years

Discontinued Operations, Good_8

Discontinued Operations, Goodwill, and Intangible Assets - Amortization Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Estimated amortization expense for the succeeding years
2022	$ 18,600
2023	18,200
2024	17,400
2025	700
Intangible Assets, Net	54,867	$ 76,917
Amortization expense	$ 22,600	$ 24,100

Revenue Recognition (Details)

Revenue Recognition (Details) - USD ($) $ in Billions	12 Months Ended
Revenue Recognition (Details) - USD ($) $ in Billions	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
ASU 2014-09
Revenue Recognition
Subcontractor and other direct costs	$ 7.2	$ 7.1	$ 7.4

Revenue Recognition - Disaggreg

Revenue Recognition - Disaggregated revenues (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Revenue Recognition
Total revenue	$ 13,340.9	$ 13,240	$ 13,642.5
Cost reimbursable
Revenue Recognition
Total revenue	5,319.4	5,734.5	5,958.2
Guaranteed maximum price
Revenue Recognition
Total revenue	4,582.7	3,896.8	3,962.6
Fixed price
Revenue Recognition
Total revenue	3,438.8	3,608.7	3,721.7
Americas
Revenue Recognition
Total revenue	10,228.3	10,138.3	10,390.8
Europe, Middle East, Africa
Revenue Recognition
Total revenue	1,588.1	1,620.3	1,752.1
Asia Pacific
Revenue Recognition
Total revenue	$ 1,524.5	$ 1,481.4	$ 1,499.6

Revenue Recognition - Performan

Revenue Recognition - Performance obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Revenue, remaining performance obligations
Performance obligation	$ 18,700
Liability recognized	$ 692	$ 592.7
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, remaining performance obligations
Performance Obligation expected timing of satisfaction period	12 months
Performance obligation, percent to be satisfied	55.00%

Revenue Recognition - Accounts

Revenue Recognition - Accounts receivable, net (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Billed	$ 2,181,100	$ 2,467,300
Contract retentions	531,200	531,300
Total accounts receivable-gross	2,712,300	2,998,600
Allowance for doubtful accounts and credit losses	(92,800)	(77,900)
Total accounts receivable-net	$ 2,619,491	$ 2,920,730
Additional disclosures
Unbilled receivables are expected to be billed and collected (in months)	12 months	12 months
Significant claims recorded in contract assets and other non-current assets	$ 140,000	$ 170,000
Trade receivables sold, outstanding	263,600	166,600
Total
Total accounts receivable-net	$ 2,619,500	$ 2,920,700
Other than U.S government outstanding receivables
Additional disclosures
Number of clients	No	No
Concentration Risk Threshold Percentage	10.00%	10.00%

Property and Equipment (Details

Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
Property and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Property and equipment
Property and equipment, gross	$ 1,080,400	$ 1,046,900
Accumulated depreciation and amortization	(681,500)	(665,200)
Property and equipment, net	398,876	381,672
Depreciation expense	143,600	163,400	$ 137,500
Building and land
Property and equipment
Property and equipment, gross	14,400	11,500
Leasehold improvements
Property and equipment
Property and equipment, gross	351,200	343,200
Computer systems and equipment
Property and equipment
Property and equipment, gross	602,100	557,400
Furniture and fixtures
Property and equipment
Property and equipment, gross	$ 112,700	$ 134,800

Property and Equipment - Useful

Property and Equipment - Useful Lives (Details)	12 Months Ended
Property and Equipment - Useful Lives (Details)	Sep. 30, 2021
Building and land \| Minimum
Property and equipment
Useful Lives	10 years
Building and land \| Maximum
Property and equipment
Useful Lives	45 years
Leasehold improvements \| Minimum
Property and equipment
Useful Lives	1 year
Leasehold improvements \| Maximum
Property and equipment
Useful Lives	20 years
Computer systems and equipment \| Minimum
Property and equipment
Useful Lives	3 years
Computer systems and equipment \| Maximum
Property and equipment
Useful Lives	12 years
Furniture and fixtures \| Minimum
Property and equipment
Useful Lives	3 years
Furniture and fixtures \| Maximum
Property and equipment
Useful Lives	10 years

Joint Ventures and Variable I_3

Joint Ventures and Variable Interest Entities - Consolidated (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Financial Information
Current assets	$ 6,173,543				$ 7,530,366				$ 6,173,543	$ 7,530,366
TOTAL ASSETS	11,733,954				12,998,951				11,733,954	12,998,951
Current liabilities	5,521,715				6,090,454				5,521,715	6,090,454
TOTAL LIABILITIES	8,904,377				9,585,407				8,904,377	9,585,407
Total AECOM equity	2,712,470				3,292,558				2,712,470	3,292,558
Noncontrolling interests	117,107				120,986				117,107	120,986
TOTAL STOCKHOLDERS' EQUITY	2,829,577				3,413,544				2,829,577	3,413,544	$ 3,899,350	$ 4,278,374
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	11,733,954				12,998,951				11,733,954	12,998,951
Revenue	3,353,800	$ 3,408,400	$ 3,265,500	$ 3,313,200	3,569,000	$ 3,189,700	$ 3,245,700	$ 3,235,600	13,340,852	13,239,976	13,642,455
Consolidated Joint Ventures
Financial Information
Current assets	503,900				536,300				503,900	536,300
Non-current assets	74,800				77,000				74,800	77,000
TOTAL ASSETS	578,700				613,300				578,700	613,300
Current liabilities	400,300				409,900				400,300	409,900
Non-current liabilities	1,500				1,500				1,500	1,500
TOTAL LIABILITIES	401,800				411,400				401,800	411,400
Total AECOM equity	74,000				113,900				74,000	113,900
Noncontrolling interests	102,900				88,000				102,900	88,000
TOTAL STOCKHOLDERS' EQUITY	176,900				201,900				176,900	201,900
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 578,700				$ 613,300				578,700	613,300
Revenue									$ 826,800	$ 787,600	$ 1,095,200

Joint Ventures and Variable I_4

Joint Ventures and Variable Interest Entities - Unconsolidated (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Financial Information
Current assets	$ 6,173,543				$ 7,530,366				$ 6,173,543	$ 7,530,366
TOTAL ASSETS	11,733,954				12,998,951				11,733,954	12,998,951
Current liabilities	5,521,715				6,090,454				5,521,715	6,090,454
TOTAL LIABILITIES	8,904,377				9,585,407				8,904,377	9,585,407
Joint ventures' equity	2,829,577				3,413,544				2,829,577	3,413,544	$ 3,899,350	$ 4,278,374
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	11,733,954				12,998,951				11,733,954	12,998,951
AECOM's investment in unconsolidated joint ventures	328,906				297,595				328,906	297,595
Joint ventures summarized financial information
Revenue	3,353,800	$ 3,408,400	$ 3,265,500	$ 3,313,200	3,569,000	$ 3,189,700	$ 3,245,700	$ 3,235,600	13,340,852	13,239,976	13,642,455
Cost of revenue	3,136,600	3,206,800	3,070,300	3,128,800	3,379,100	3,004,600	3,076,900	3,069,800	12,542,431	12,530,416	13,030,800
Gross profit	217,200	201,600	195,200	184,400	189,900	185,100	168,800	165,800	798,421	709,560	611,655
Net income	106,300	$ 18,400	$ 45,300	$ 33,000	(223,900)	$ 94,100	$ (77,000)	$ 53,100	202,980	(153,741)	$ (183,990)
Unconsolidated Joint Ventures
Financial Information
Current assets	1,323,200				1,374,300				1,323,200	1,374,300
Non-current assets	1,001,600				465,800				1,001,600	465,800
TOTAL ASSETS	2,324,800				1,840,200				2,324,800	1,840,200
Current liabilities	845,800				953,400				845,800	953,400
Non-current liabilities	537,200				58,900				537,200	58,900
TOTAL LIABILITIES	1,383,000				1,012,300				1,383,000	1,012,300
Joint ventures' equity	941,800				827,900				941,800	827,900
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	2,324,800				1,840,200				2,324,800	1,840,200
AECOM's investment in unconsolidated joint ventures	$ 328,900				$ 297,600				328,900	297,600
Joint ventures summarized financial information
Revenue									2,096,500	3,058,900
Cost of revenue									2,051,200	2,993,100
Gross profit									45,300	65,800
Net income									$ 37,000	$ 59,800

Joint Ventures and Variable I_5

Joint Ventures and Variable Interest Entities - Equity in Earnings (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Financial Information
Equity in earnings of joint ventures	$ 11,400	$ 8,200	$ 7,200	$ 8,200	$ 16,800	$ 8,600	$ 13,500	$ 9,900	$ 35,044	$ 48,781	$ 49,320
Pass through joint ventures
Financial Information
Equity in earnings of joint ventures									23,600	34,100	31,600
Other joint ventures
Financial Information
Equity in earnings of joint ventures									$ 11,400	$ 14,700	$ 17,700

Pension Benefit Obligations (De

Pension Benefit Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
United States
Change in benefit obligation:
Benefit obligation at beginning of year	$ 283.9	$ 275.6	$ 257.1
Participant contributions	0.1		0.1
Interest cost	4.3	6.8	9.5
Benefits and expenses paid	(18.5)	(18.4)	(17.6)
Actuarial (gain) loss	(3.7)	22	27.8
Plan settlements	(0.7)	(2.1)	(1.3)
Benefit obligation at end of year	265.4	283.9	275.6
International
Change in benefit obligation:
Benefit obligation at beginning of year	1,440.3	1,311.3	1,188.8
Service cost	0.5	0.6	0.5
Participant contributions	0.3	0.3	0.3
Interest cost	21.6	22.4	29.7
Benefits and expenses paid	(48.6)	(42.9)	(41.3)
Actuarial (gain) loss	(4.7)	82.8	206.5
Plan settlements	(5.9)	(4.1)	(3.7)
Plan amendments	0.4		5.2
Foreign currency translation (gain) loss	66.9	69.9	(74.7)
Benefit obligation at end of year	$ 1,470.8	$ 1,440.3	$ 1,311.3

Pension Benefit Obligations - A

Pension Benefit Obligations - Asset Changes (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Change in plan assets
Fair value of plan assets at beginning of year	$ 1,295.8
Employer contributions to Multiemployer Pension Plans	3.7	$ 4
Fair value of plan assets at end of year	1,390.7	1,295.8
United States
Change in plan assets
Fair value of plan assets at beginning of year	129.6	129.3	$ 131.4
Actual return on plan assets	14.7	11.7	4.5
Employer contributions to Multiemployer Pension Plans	13.7	9.1	12.2
Participant contributions	0.1		0.1
Benefits and expenses paid	(18.5)	(18.4)	(17.6)
Plan settlements	(0.7)	(2.1)	(1.3)
Fair value of plan assets at end of year	138.9	129.6	129.3
International
Change in plan assets
Fair value of plan assets at beginning of year	1,166.2	1,068.8	965.9
Actual return on plan assets	61.1	59.5	180.3
Employer contributions to Multiemployer Pension Plans	25.2	27.7	28.2
Participant contributions	0.3	0.3	0.3
Benefits and expenses paid	(48.6)	(42.9)	(41.3)
Plan settlements	(5.9)	(4.1)	(3.7)
Foreign currency translation gain (loss)	53.5	56.9	(60.9)
Fair value of plan assets at end of year	$ 1,251.8	$ 1,166.2	$ 1,068.8

Pension Benefit Obligations - F

Pension Benefit Obligations - Funded Status (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
United States
Reconciliation of funded status:
Funded status at end of year	$ (126.5)	$ (154.3)	$ (146.3)
Net amount recognized at end of year	(126.5)	(154.3)	(146.3)
International
Reconciliation of funded status:
Funded status at end of year	(219)	(274.1)	(242.5)
Net amount recognized at end of year	$ (219)	$ (274.1)	$ (242.5)

Pension Benefit Obligations - B

Pension Benefit Obligations - Balance Sheet Recognition (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Amounts recognized in the consolidated balance sheets:
Pension benefit obligations	$ (383,904)	$ (463,001)
United States
Amounts recognized in the consolidated balance sheets:
Accrued expenses and other current liabilities	(9,100)	(9,400)	$ (9,000)
Pension benefit obligations	(117,400)	(144,900)	(137,300)
Net amount recognized in the balance sheet	(126,500)	(154,300)	(146,300)
International
Amounts recognized in the consolidated balance sheets:
Other non-current assets	47,500	44,000	28,300
Pension benefit obligations	(266,500)	(318,100)	(270,800)
Net amount recognized in the balance sheet	$ (219,000)	$ (274,100)	$ (242,500)

Pension Benefit Obligations - E

Pension Benefit Obligations - Equity Recognition (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
United States
Reconciliation of amounts in consolidated statements of stockholders' equity:
Prior service (cost) credit	$ (0.1)	$ (0.1)	$ (0.7)
Net loss	(116.5)	(134.5)	(122.4)
Total recognized in accumulated other comprehensive loss	(116.6)	(134.6)	(123.1)
International
Reconciliation of amounts in consolidated statements of stockholders' equity:
Prior service (cost) credit	(1.6)	(1.2)	(1.2)
Net loss	(279.5)	(297.7)	(233)
Total recognized in accumulated other comprehensive loss	$ (281.1)	$ (298.9)	$ (234.2)

Pension Benefit Obligations - P

Pension Benefit Obligations - Periodic Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Pension Plan, Defined Benefit
Percentage of Plan Assets:
Applicable deferred income taxes, included in OCI arising from net prior service cost and net gain/loss	$ 9.3	$ 15.5	$ 16.3
United States
Percentage of Plan Assets:
Interest cost on projected benefit obligation	4.3	6.8	9.5
Expected return on plan assets	(6.5)	(7)	(9)
Amortization of prior service costs (credits)		0.1	0.1
Amortization of net loss	5.9	4.7	3.7
Curtailment loss recognized		0.5
Settlement loss recognized	0.2	0.6	0.2
Net periodic benefit cost	3.9	5.7	4.5
International
Percentage of Plan Assets:
Service costs	0.5	0.6	0.5
Interest cost on projected benefit obligation	21.6	22.4	29.7
Expected return on plan assets	(43.5)	(37.5)	(38.1)
Amortization of prior service costs (credits)	0.1	0.1	(0.1)
Amortization of net loss	9.2	8.6	4.1
Settlement loss recognized	0.8	0.5	0.8
Net periodic benefit cost	$ (11.3)	$ (5.3)	$ (3.1)

Pension Benefit Obligations -_2

Pension Benefit Obligations - AOCI (Details) $ in Millions	Sep. 30, 2021USD ($)
United States
Amounts included in AOCI that are expected to be recognized as components of net periodic benefit cost during the next fiscal year
Amortization of net actuarial losses	$ (5.6)
Total	(5.6)
International
Amounts included in AOCI that are expected to be recognized as components of net periodic benefit cost during the next fiscal year
Amortization of prior service credit	(0.1)
Amortization of net actuarial losses	(7.4)
Total	$ (7.5)

Pension Benefit Obligations -_3

Pension Benefit Obligations - Excess of Plan Assets (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
United States
Additional year-end information for pension plans with accumulated benefit obligations in excess of plan assets
Projected benefit obligation	$ 247.8	$ 265.1	$ 257.3
Accumulated benefit obligation	247.8	265.1	257.3
Fair values of plan assets	138.9	129.6	129.3
Expected employer contributions in next fiscal year	11.4
International
Additional year-end information for pension plans with accumulated benefit obligations in excess of plan assets
Projected benefit obligation	1,248.8	1,216.6	1,141.9
Accumulated benefit obligation	1,243.9	1,211.5	1,132.7
Fair values of plan assets	982.4	$ 898.5	$ 871.2
Expected employer contributions in next fiscal year	$ 24.8

Pension Benefit Obligations -_4

Pension Benefit Obligations - Future payments (Details) $ in Millions	Sep. 30, 2021USD ($)
United States
Expected future benefit payments
2022	$ 21
2023	21.4
2024	20
2025	19.7
2026	19.6
2027-2031	83.6
Total	185.3
International
Expected future benefit payments
2022	58.6
2023	57.4
2024	58.6
2025	60.1
2026	61.9
2027-2031	339.1
Total	$ 635.7

Pension Benefit Obligations - U

Pension Benefit Obligations - Underlying assumptions (Details)	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
United States
Weighted-average assumptions to determine benefit obligation:
Discount rate (as a percent)	2.46%	2.20%	2.92%
Weighted-average assumptions to determine net periodic benefit cost:
Discount rate (as a percent)	2.20%	2.92%	4.10%
Expected long-term rate of return on plan assets (as a percent)	6.80%	7.30%	7.00%
International
Weighted-average assumptions to determine benefit obligation:
Discount rate (as a percent)	1.98%	1.67%	1.81%
Salary increase rate (as a percent)	3.13%	2.68%	2.52%
Weighted-average assumptions to determine net periodic benefit cost:
Discount rate (as a percent)	1.67%	1.81%	2.91%
Salary increase rate (as a percent)	2.68%	2.52%	2.79%
Expected long-term rate of return on plan assets (as a percent)	3.95%	4.03%	4.43%

Pension Benefit Obligations - T

Pension Benefit Obligations - Target Allocation and Plan Assets Allocations (Details)	Sep. 30, 2021	Sep. 30, 2020
United States
Percentage of Plan Assets:
Target allocations (as a percent)	100.00%
Plan assets (as a percent)	100.00%	100.00%
United States \| Equities
Percentage of Plan Assets:
Target allocations (as a percent)	40.00%
Plan assets (as a percent)	41.00%	47.00%
United States \| Debt.
Percentage of Plan Assets:
Target allocations (as a percent)	48.00%
Plan assets (as a percent)	44.00%	42.00%
United States \| Cash and cash equivalents
Percentage of Plan Assets:
Target allocations (as a percent)	2.00%
Plan assets (as a percent)	5.00%	1.00%
United States \| Property And Other
Percentage of Plan Assets:
Target allocations (as a percent)	10.00%
Plan assets (as a percent)	10.00%	10.00%
International
Percentage of Plan Assets:
Target allocations (as a percent)	100.00%
Plan assets (as a percent)	100.00%	100.00%
International \| Equities
Percentage of Plan Assets:
Target allocations (as a percent)	34.00%
Plan assets (as a percent)	34.00%	26.00%
International \| Debt.
Percentage of Plan Assets:
Target allocations (as a percent)	54.00%
Plan assets (as a percent)	53.00%	54.00%
International \| Cash and cash equivalents
Percentage of Plan Assets:
Target allocations (as a percent)	2.00%
Plan assets (as a percent)	3.00%	4.00%
International \| Property And Other
Percentage of Plan Assets:
Target allocations (as a percent)	10.00%
Plan assets (as a percent)	10.00%	16.00%

Pension Benefit Obligations -_5

Pension Benefit Obligations - Asset Categories (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Post-retirement plan
Fair values of plan assets	$ 1,390.7	$ 1,295.8
Cash and cash equivalents
Post-retirement plan
Fair values of plan assets	49.8	50.6
Equity and debt securities
Post-retirement plan
Fair values of plan assets	488.5	442.3
Diversified and equity funds
Post-retirement plan
Fair values of plan assets	81.2	31.5
Fixed income funds
Post-retirement plan
Fair values of plan assets	29.3	36.2
Common collective funds
Post-retirement plan
Fair values of plan assets	734.8	707.5
Derivative instruments
Post-retirement plan
Fair values of plan assets	7.1	27.7
Level 1
Post-retirement plan
Fair values of plan assets	599.1	498.6
Level 1 \| Cash and cash equivalents
Post-retirement plan
Fair values of plan assets	25.1	20.2
Level 1 \| Equity and debt securities
Post-retirement plan
Fair values of plan assets	488.5	442.3
Level 1 \| Diversified and equity funds
Post-retirement plan
Fair values of plan assets	60.5	13
Level 1 \| Fixed income funds
Post-retirement plan
Fair values of plan assets	25	23.1
Level 2
Post-retirement plan
Fair values of plan assets	52.8	86.3
Level 2 \| Cash and cash equivalents
Post-retirement plan
Fair values of plan assets	24.7	30.4
Level 2 \| Diversified and equity funds
Post-retirement plan
Fair values of plan assets	16.7	15.1
Level 2 \| Fixed income funds
Post-retirement plan
Fair values of plan assets	4.3	13.1
Level 2 \| Derivative instruments
Post-retirement plan
Fair values of plan assets	7.1	27.7
Level 3
Post-retirement plan
Fair values of plan assets	4	3.4	$ 26.8
Level 3 \| Diversified and equity funds
Post-retirement plan
Fair values of plan assets	4	3.4
Investments measured at NAV
Post-retirement plan
Fair values of plan assets	734.8	707.5
Investments measured at NAV \| Common collective funds
Post-retirement plan
Fair values of plan assets	$ 734.8	$ 707.5

Pension Benefit Obligations - L

Pension Benefit Obligations - Level 3 (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Changes in the fair value of Level 3 assets
Fair value of plan assets at beginning of year	$ 1,295.8
Fair value of plan assets at end of year	1,390.7	$ 1,295.8
Level 3
Changes in the fair value of Level 3 assets
Fair value of plan assets at beginning of year	3.4	26.8
Actual return on plan assets, relating to assets still held at reporting date	0.4	(0.2)
Actual return on plan assets, relating to assets sold during the period		(2.1)
Purchases, sales and settlements	0.2	(25.4)
Transfer into / (out of) Level 3		3.2
Change due to exchange rate changes		1.1
Fair value of plan assets at end of year	$ 4	$ 3.4

Pension Benefit Obligations - M

Pension Benefit Obligations - Multiemployer (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Pension Benefit Obligations
Aggregate contributions to plans	$ 3.7	$ 4

Debt (Details)

Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020
Debt
Total debt	$ 2,235,600	$ 2,085,000
Less: Current portion of debt and short-term borrowings	(53,800)	(20,900)
Less: Unamortized debt issuance costs	(24,100)	(23,000)
Long-term debt	2,157,740	2,041,136
Credit Agreement
Debt
Total debt	1,155,300	248,500
2024 Senior Notes
Debt
Total debt		797,300
2027 Senior Notes
Debt
Total debt	997,300	997,300
Other Debt
Debt
Total debt	$ 83,000	$ 41,900

Debt - Scheduled Maturities (De

Debt - Scheduled Maturities (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020
Debt
2022	$ 53.8
2023	45.9
2024	41
2025	35.1
2026	400.4
Thereafter	1,659.4
Total debt	$ 2,235.6	$ 2,085

Debt - 2014 Credit Agreement (D

Debt - 2014 Credit Agreement (Details)	Jun. 25, 2021USD ($)	Feb. 08, 2021USD ($)	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Apr. 13, 2021USD ($)
Debt agreements
Proceeds from secured delayed draw term loan facility			$ 3,638,916,000	$ 4,452,078,000	$ 7,700,774,000
Credit Agreement
Debt agreements
Consolidated leverage ratio		4	2.4
Consolidated interest coverage ratio		3
Credit Agreement \| Term loan A
Debt agreements
Maximum borrowing capacity		$ 246,968,737.50
Proceeds from secured delayed draw term loan facility	$ 215,000,000
Credit Agreement \| Term loan A \| LIBOR
Debt agreements
Interest rate, basis spread (as a percent)		1.50%
Credit Agreement \| Term loan B \| Base Rate
Debt agreements
Interest rate, basis spread (as a percent)		0.50%
Credit Agreement \| Term B facility
Debt agreements
Maximum borrowing capacity						$ 700,000,000
Consolidated leverage ratio						1.75
Consolidated interest coverage ratio						0.75
Credit Agreement \| Revolving credit facility
Debt agreements
Maximum borrowing capacity		$ 1,150,000,000
Current borrowing capacity			$ 1,144,800,000	1,331,000,000
Outstanding letters of credit			$ 5,200,000	$ 19,000,000
2024 Senior Notes
Debt agreements
Cash tender						$ 700,000,000
Interest rate (as a percent)	5.875%					5.875%

Debt - 2024 Senior Notes (Detai

Debt - 2024 Senior Notes (Details) - USD ($)

Jun. 25, 2021

Sep. 30, 2021

Jun. 30, 2021

Mar. 31, 2021

Dec. 31, 2020

Sep. 30, 2020

Jun. 30, 2020

Mar. 31, 2020

Dec. 31, 2019

Sep. 30, 2021

Sep. 30, 2020

Sep. 30, 2019

Apr. 13, 2021

Oct. 06, 2014

Debt

Interest expense

$ (25,900,000)

$ (149,000,000)

$ (32,800,000)

$ (30,700,000)

$ (47,500,000)

$ (35,000,000)

$ (37,100,000)

$ (40,400,000)

$ (238,352,000)

$ (159,914,000)

$ (161,482,000)

2014 Senior Notes | The 2024 Notes

Debt

Interest expense

$ 217,500,000

2024 Senior Notes

Debt

Cash tender

$ 700,000,000

Interest rate (as a percent)

5.875%

2024 Senior Notes | The 2024 Notes

Debt

Face amount

$ 800,000,000

Interest rate (as a percent)

5.875%

Fair value of debt instrument

$ 117,500,000

Redemption price (in percent)

115.108%

Debt - 2017 Senior Notes (Detai

Debt - 2017 Senior Notes (Details) - 2027 Senior Notes - USD ($)	Feb. 21, 2017	Sep. 30, 2021
Debt
Face amount	$ 1,000,000,000
Fair value of debt instrument		$ 1,104,500,000
Interest rate (as a percent)	5.125%
At any time and from time to time prior to December 15, 2026
Debt
Redemption price (in percent)	100.00%
At any time on or after December 15, 2026
Debt
Redemption price (in percent)	100.00%

Debt - URS Senior Notes (Detail

Debt - URS Senior Notes (Details) - USD ($) $ in Thousands	Aug. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019	Oct. 17, 2014
Debt
Repayments of debt		$ 797,252	$ 248,522
Proceeds from secured delayed draw term loan facility		3,638,916	4,452,078	$ 7,700,774
Prepayment premium on redemption of unsecured senior notes		$ 117,500	$ 16,986
URS Senior Notes
Debt
Prepayment premium on redemption of unsecured senior notes	$ 17,000
URS Senior Notes \| 2022 URS Senior Notes
Debt
Interest rate (as a percent)					5.00%
Redemption price (as percent of principal)	106.835%
Repayments of debt	$ 248,500
Proceeds from secured delayed draw term loan facility	$ 248,500

Debt - Other Debt and Other Ite

Debt - Other Debt and Other Items (Details) - Other Debt - Standby letter of credit - Unsecured - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020
Debt
Outstanding letters of credit	$ 478.5	$ 510.1
Current borrowing capacity	$ 463.6

Debt - Effective Interest Rate

Debt - Effective Interest Rate (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Debt
Effective interest rate including effects of interest rate swap agreements	4.4%	5.3%	5.1%
Amortization of deferred debt issuance costs	$ 10.2	$ 5.4	$ 5

Derivative Financial Instrume_3

Derivative Financial Instruments and Fair Value Measurements - Cash Flow Hedges (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020
Derivative financial instruments
Fixed Rate (as a percent)	1.349%
Interest rate swap agreements
Derivative financial instruments
Notional Amount	$ 400
Designated as Hedging Instrument \| Cash Flow Hedging \| Interest rate swap agreements \| USD \| March 2018
Derivative financial instruments
Notional Amount	$ 200	$ 200
Fixed Rate (as a percent)	2.60%	2.60%
Designated as Hedging Instrument \| Cash Flow Hedging \| Interest rate swap agreements \| USD \| February 2023
Derivative financial instruments
Notional Amount	$ 400
Fixed Rate (as a percent)	1.349%

Derivative Financial Instrume_4

Derivative Financial Instruments and Fair Value Measurements - Fair Value Measurements (Details) $ in Millions	12 Months Ended
	Sep. 30, 2021USD ($)
Designated as Hedging Instrument \| Cash Flow Hedging \| Interest rate swap agreements
Derivative financial instruments
Losses recognized in income	$ 0

Leases - Components of lease ex

Leases - Components of lease expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Oct. 01, 2019
New Accounting Pronouncements and Changes in Accounting
(Accumulated deficits) / Retained earnings	$ (504,126)	$ 174,248
Operating lease cost
Operating lease cost	186,500	191,600
Finance lease cost:
Amortization of right-of-use assets	13,000	17,100
Interest on lease liabilities	2,000	1,900
Variable lease cost	35,500	36,500
Total lease cost	$ 237,000	$ 247,100
ASU 2016-02
New Accounting Pronouncements and Changes in Accounting
(Accumulated deficits) / Retained earnings			$ 87,800

Leases - Additional balance she

Leases - Additional balance sheet information (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020
ASSETS
Operating lease assets	$ 607,076	$ 652,115
Balance Sheet classification of operating lease assets	Operating lease assets	Operating lease assets
Finance lease assets	$ 44,400	$ 29,100
Balance Sheet classification of finance lease assets	PROPERTY AND EQUIPMENT-NET	PROPERTY AND EQUIPMENT-NET
Total lease assets	$ 651,500	$ 681,200
Current:
Operating lease liabilities	$ 157,300	$ 168,400
Balance Sheet classification of operating lease liabilities	Accrued expenses and other current liabilities	Accrued expenses and other current liabilities
Finance lease liabilities	$ 13,400	$ 9,800
Balance Sheet classification of finance lease liabilities	Current portion of long-term debt	Current portion of long-term debt
Total current lease liabilities	$ 170,700	$ 178,200
Operating lease liabilities	$ 679,059	$ 745,287
Balance Sheet classification of operating lease liabilities	Operating lease liabilities	Operating lease liabilities
Finance lease liabilities	$ 32,100	$ 22,000
Balance Sheet classification of finance lease liabilities	LONG-TERM DEBT	LONG-TERM DEBT
Total non-current lease liabilities	$ 711,200	$ 767,300
Weighted average remaining lease term (in years):
Operating leases	6 years 10 months 24 days	7 years 3 months 18 days
Finance leases	3 years 6 months	3 years 3 months 18 days
Weighted average discount rates:
Operating leases	4.30%	4.60%
Finance leases	4.30%	4.70%

Leases - Additional cash flow i

Leases - Additional cash flow information (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 221.4	$ 208.7
Operating cash flows from finance leases	2	1.8
Financing cash flows from finance leases	13.7	14.7
Right-of-use assets obtained in exchange for new operating leases	102.7	126.9
Right-of-use assets obtained in exchange for new finance leases	$ 28.5	$ 26.4

Leases - Total remaining lease

Leases - Total remaining lease payments under the Company's operating lease (Details) $ in Millions	Sep. 30, 2021USD ($)
Amounts payable under non-cancelable operating lease commitments
2022	$ 190
2023	156.2
2024	134.7
2025	114.9
2026	91.6
Thereafter	286.8
Total lease payments	974.2
Less: Amounts representing interest	(137.8)
Total lease liabilities	$ 836.4

Leases - Total remaining leas_2

Leases - Total remaining lease payments under the Company's Finance lease (Details) $ in Millions	Sep. 30, 2021USD ($)
Leases
2022	$ 15.2
2023	14.9
2024	11.7
2025	5.8
2026	1.5
Total lease payments	49.1
Less: Amounts representing interest	(3.6)
Total lease liabilities	$ 45.5

Share-Based Payments - Incentiv

Share-Based Payments - Incentive Plans (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Stock Incentive Plans
Employer contributions, compensation expense	$ 26.1	$ 33.7	$ 32.3
Employee Stock Option
Stock Incentive Plans
Securities available for future issuance (in shares)	12.1
Expiration term of unexercised options	7 years
Number of Options
Balance at the beginning of the period (in shares)	0.4	0.1	0.6
Granted (in shares)		0.3
Exercised (in shares)	(0.1)
Cancelled (in shares)			(0.5)
Balance at the end of the period (in shares)	0.3	0.4	0.1
Exercisable at the end of the period (in shares)		0.1	0.1
Stock options, Weighted average exercise price
Balance at the beginning of the period (in dollars per share)	$ 36.41	$ 31.62	$ 31.62
Granted (in dollars per share)		38.72
Exercised (in dollars per share)	31.62
Cancelled (in dollars per share)			(31.62)
Balance at the end of the period (in dollars per share)	$ 38.72	36.41	31.62
Exercisable at the end of the period (in dollars per share)		$ 31.62	$ 31.62

Share-Based Payments - Exercisa

Share-Based Payments - Exercisable Options (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Information concerning outstanding and exercisable options
Allocated Share-based Compensation Expense	$ 44.7	$ 54.2	$ 63.8
Unrecognized compensation expense	$ 45.6	$ 50
Vesting period	3 years
Employee Stock Option
Information concerning outstanding and exercisable options
Weighted average grant-date fair value of stock options granted (in dollars per share)	$ 11.30
Performance Earnings Program
Information concerning outstanding and exercisable options
Weighted average grant-date fair value of stock options granted (in dollars per share)	$ 52.76	$ 42.99	$ 27.53
Vesting period	3 years
Restricted Stock Units
Information concerning outstanding and exercisable options
Weighted average grant-date fair value of stock options granted (in dollars per share)	$ 49.21	$ 41.90	$ 27.73

Income Taxes - Tax (Benefit) Ex

Income Taxes - Tax (Benefit) Expense (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Loss (income) from domestic operations before income tax expense									$ 98,600	$ 52,900	$ 133,000
Income (loss) from foreign operations before income tax expense									310,200	179,700	116,200
Current:
Federal									32,200	21,800	(17,300)
State									6,800	12,700	29,800
Foreign									53,200	55,700	41,700
Total current income tax expense									92,200	90,200	54,200
Deferred:
Federal									(28,800)	(21,800)	(26,100)
State									18,800	12,800	(24,600)
Foreign									6,800	(35,400)	10,000
Total deferred income tax benefit									(48,265)	11,130	(98,015)
Total income tax expense	$ 46,100	$ (17,800)	$ 35,100	$ 25,600	$ 15,300	$ (7,200)	$ 21,700	$ 15,900	89,011	45,753	13,498
Total
Deferred:
Total deferred income tax benefit									(3,200)	(44,400)	(40,700)
Total income tax expense									$ 89,000	$ 45,800	$ 13,500

Income Taxes - Federal Rate Rec

Income Taxes - Federal Rate Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Rate reconciliation
Tax at federal statutory rate									$ 85,800	$ 48,800	$ 52,000
State income tax, net of federal benefit									8,000	8,400	7,000
Foreign residual income									45,600	39,500	35,800
Valuation allowance									12,400	(15,900)	(26,500)
Audit settlement									10,400		(4,600)
Foreign tax rate differential									8,800	3,200	(3,100)
Change in uncertain tax positions									8,500	(8,300)	5,600
Nondeductible costs									6,000	15,800	7,600
Income tax credits and incentives									(51,300)	(47,800)	(44,700)
Tax rate changes									(26,800)	(500)	(1,900)
Return to provision									(9,500)	5,100	(200)
Exclusion of tax on non-controlling interests									(6,100)	(3,400)	(5,300)
Tax exempt income									(5,400)	(5,100)	(3,900)
Other items, net									2,600	6,000	(4,300)
Total income tax expense	$ 46,100	$ (17,800)	$ 35,100	$ 25,600	$ 15,300	$ (7,200)	$ 21,700	$ 15,900	$ 89,011	$ 45,753	$ 13,498
Major elements contributing to the difference between the U.S. federal statutory rate of 21% for fiscal year 2020 and 24.5% for fiscal years ended 2019 and 2018 and the effective tax rate
Tax at federal statutory rate (as a percent)									21.00%	21.00%	21.00%
State income tax, net of federal benefit (as a percent)									2.00%	3.60%	2.80%
Foreign residual income (as a percent)									11.10%	17.00%	14.50%
Valuation allowance (as a percent)									3.00%	(6.90%)	(10.70%)
Audit settlement (as a percent)									2.50%		(1.90%)
Foreign tax rate differential (as a percent)									2.10%	1.40%	(1.30%)
Change in uncertain tax positions (as a percent)									2.10%	(3.60%)	2.30%
Nondeductible costs (as a percent)									1.50%	6.80%	3.10%
Income tax credits and incentive (as a percent)									(12.50%)	(20.60%)	(18.10%)
Tax rate changes (as a percent)									(6.50%)	(0.20%)	(0.80%)
Return to provision (as a Percent)									(2.30%)	2.20%	(0.10%)
Exclusion of tax on non-controlling interests (as a percent)									(1.50%)	(1.50%)	(2.10%)
Tax exempt income (as a percent)									(1.30%)	(2.20%)	(1.60%)
Other items, net (as a percent)									0.60%	2.70%	(1.70%)
Total income tax expense (as a percent)		25.00%	19.00%						21.80%	19.70%	5.40%

Income Taxes - Additional infor

Income Taxes - Additional information (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Income taxes
Effective tax rate (as a percent)	25.00%	19.00%	21.80%	19.70%	5.40%
Valuation allowance related to net operating losses and other deferred tax assets			$ 197.7	$ 217.5
Corporate tax rate			21.00%	21.00%	21.00%
Tax expense related to audit settlement			$ 13.2
Tax rate changes			(26.8)	$ (0.5)	$ (1.9)
Tax benefit from foreign subsidiaries			(53.2)	(55.7)	(41.7)
Change in valuation allowance			19.8
United States
Income taxes
Valuation allowance related to net operating losses and other deferred tax assets					38.1
Tax benefit from income tax examination					$ 38.1
United Kingdom
Income taxes
Tax rate changes			$ 25.9
Canada
Income taxes
Valuation allowance related to net operating losses and other deferred tax assets				$ 31.7

Income Taxes - Deferred tax (De

Income Taxes - Deferred tax (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Deferred tax assets:
Compensation and benefit accruals not currently deductible	$ 130	$ 119.4
Net operating loss carryforwards	169.8	173.2
Self-insurance reserves	12.3	17.6
Research and experimentation and other tax credits	117.2	112.9
Pension liability	87.7	95.1
Accrued liabilities	284.7	307.6
Capital loss carryforward	62	104.8
Other	37.3	26
Total deferred tax assets	901	956.6
Deferred tax liabilities:
Unearned revenue	(19.8)	(40.3)
Depreciation and amortization	(116.5)	(106.7)
Acquired intangible assets	(19.4)	(24.5)
Investment in subsidiaries	(13.4)	(10.9)
Right of use assets	(145.6)	(164.9)
Contingent consideration	(33.8)	(33.6)
Total deferred tax liabilities	(348.5)	(380.9)
Valuation allowance	197.7	217.5
Net deferred tax assets	354.8	358.2
Income Taxes, additional disclosures
Remaining gross tax asset exclusive of tax liabilities realized	703.3
Change in valuation allowance	19.8
Valuation allowance related to capital losses.	49.5
Change in valuation allowance for foreign tax credits	29.6
Gross book-tax differences from non-U.S. subsidiaries	1,500
Liability for unrecognized tax benefits, including potential interest and penalties, net of related tax benefit	62.8	65.8
Unrecognized tax benefits	46.4	47.1	$ 55.7
Unrecognized tax benefits that would be included in the effective tax rate if recognized	40.1
Capital loss carryforwards	184.1	355.7
Canada
Deferred tax liabilities:
Valuation allowance		31.7
United States
Deferred tax liabilities:
Valuation allowance			$ 38.1
California Franchise Tax Board \| Enterprise Zone Tax Credits
Income Taxes, additional disclosures
Unused tax credits	18.1
Federal
Income Taxes, additional disclosures
Liability for unrecognized tax benefits, including potential interest and penalties, net of related tax benefit	46.4	47.1
Federal \| Research and development
Income Taxes, additional disclosures
Unused tax credits	75.7
State
Income Taxes, additional disclosures
Net operating loss carryforwards	667
State \| Research and development
Income Taxes, additional disclosures
Unused tax credits	$ 23.4
Foreign
Income Taxes, additional disclosures
Net operating loss carryforwards		$ 710.2

Income Taxes - Gross Unrecogniz

Income Taxes - Gross Unrecognized (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Reconciliation of the beginning and ending amount of gross unrecognized tax benefits
Balance at the beginning of the year	$ 47.1	$ 55.7
Gross increase in current period's tax positions	4.3	2.8
Gross increase in prior years' tax positions	7.5
Gross decrease in prior years' tax positions		(7.9)
Decrease due to settlement with tax authorities	(1.3)	(0.5)
Decrease due to lapse of statute of limitations		(3.5)
Gross change due to foreign exchange fluctuations	(11.2)	0.5
Balance at the end of the year	46.4	47.1
Income Taxes, additional disclosures
Accrued interest, excluding any related income tax benefits	20	18.9
Accrued penalties, excluding any related income tax benefits	$ 3.9	$ 2.7

Earnings Per Share (Details)

Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended								12 Months Ended
Earnings Per Share (Details) - shares shares in Thousands	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share
Denominator for basic earnings per share	143,800	146,100	147,800	151,400	160,000	160,100	158,600	157,300	147,279	159,005	157,044
Potential common shares									2,400	2,300	2,700
Denominator for diluted earnings per share	146,600	148,900	149,500	153,700	160,000	161,800	160,700	160,600	149,676	161,292	159,684

Other Financial Information (De

Other Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Accrued expenses and other current liabilities
Accrued salaries and benefits	$ 661,800				$ 675,700				$ 661,800	$ 675,700
Accrued contract costs	1,202,100				1,137,500				1,202,100	1,137,500
Other accrued expenses	310,300				436,500				310,300	436,500
Total accrued expenses	2,174,201				2,249,704				2,174,201	2,249,704
Restructuring costs	14,000	$ 13,000	$ 8,800	$ 13,000	91,900	$ 20,300	$ 31,200	$ 44,900	48,840	188,345	$ 95,446
Loss related to remeasurement of self perform at risk construction business to fair value less cost to sell											$ 24,900
Accrued restructuring expenses	5,200				56,200				5,200	56,200
Personnel and other costs
Accrued expenses and other current liabilities
Restructuring costs									37,800	149,200
Real estate costs
Accrued expenses and other current liabilities
Restructuring costs									11,000	39,100
Loss related to remeasurement of self perform at risk construction business to fair value less cost to sell										27,400
Professional liability accrual
Accrued expenses and other current liabilities
Accrued contract costs	$ 736,400				$ 596,000				$ 736,400	$ 596,000

Reclassifications out of Accu_3

Reclassifications out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Accumulated balances
Balance at the beginning of the period	$ (918,674)	$ (864,200)	$ (703,300)
Other comprehensive (loss) income before reclassification	2,600	(96,400)	(170,900)
Amounts reclassified from accumulated other comprehensive loss	15,700	41,900	10,000
Balance at the end of the period	(900,377)	(918,674)	(864,200)
Pension Related Adjustments
Accumulated balances
Balance at the beginning of the period	(342,800)	(302,700)	(202,300)
Other comprehensive (loss) income before reclassification	14,600	(72,500)	(107,200)
Amounts reclassified from accumulated other comprehensive loss	12,000	32,400	6,800
Balance at the end of the period	(316,200)	(342,800)	(302,700)
Foreign Currency Translation Adjustments
Accumulated balances
Balance at the beginning of the period	(567,300)	(548,700)	(502,200)
Other comprehensive (loss) income before reclassification	(12,800)	(18,600)	(46,500)
Balance at the end of the period	(580,100)	(567,300)	(548,700)
Loss on Derivative Instruments
Accumulated balances
Balance at the beginning of the period	(8,600)	(12,800)	1,200
Other comprehensive (loss) income before reclassification	800	(5,300)	(17,200)
Amounts reclassified from accumulated other comprehensive loss	3,700	9,500	3,200
Balance at the end of the period	$ (4,100)	$ (8,600)	$ (12,800)

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Millions	Jan. 31, 2020	Apr. 30, 2019	Dec. 31, 2019	Apr. 30, 2019	Mar. 31, 2019	Sep. 30, 2021	Dec. 06, 2019	Dec. 31, 2014
New York
Commitments and Contingencies
Contingency liability						$ 146
Percentage of claim recoveries due to seller	10.00%
Percentage of claim recoveries due to purchaser	90.00%
Montana
Commitments and Contingencies
Damages sought		$ 132		$ 132	$ 79
Damages sought, counter party			$ 93
Department of Energy \| New York \| Minimum
Commitments and Contingencies
Contingency liability						106
Department of Energy \| New York \| Maximum
Commitments and Contingencies
Contingency liability						146
Fund investment capital commitments
Commitments and Contingencies
Commitment						$ 19.3
Commitment period						7 years
Standby letters of credit
Commitments and Contingencies
Contingency liability						$ 483
Surety Bond
Commitments and Contingencies
Contingency liability						4,300
Collectibility of Receivables
Commitments and Contingencies
Unapproved change orders								$ 103
Collectibility of Receivables \| New York
Commitments and Contingencies
Unapproved change orders							$ 60.4
Collectibility of Receivables \| New York \| Minimum
Commitments and Contingencies
Damages sought						148.5
Collectibility of Receivables \| New York \| Maximum
Commitments and Contingencies
Damages sought						329.4
Collectibility of Receivables \| Montana
Commitments and Contingencies
Unapproved change orders						90
Damages sought						$ 144

Reportable Segments and Geogr_3

Reportable Segments and Geographic Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Summarized financial information concerning the Company's reportable segments
Revenue	$ 3,353,800	$ 3,408,400	$ 3,265,500	$ 3,313,200	$ 3,569,000	$ 3,189,700	$ 3,245,700	$ 3,235,600	$ 13,340,852	$ 13,239,976	$ 13,642,455
Gross profit	217,200	201,600	195,200	184,400	189,900	185,100	168,800	165,800	798,421	709,560	611,655
Equity in earnings of joint ventures	11,400	8,200	7,200	8,200	16,800	8,600	13,500	9,900	35,044	48,781	49,320
General and administrative expenses	(44,300)	(36,300)	(36,000)	(38,400)	(49,500)	(54,500)	(41,000)	(43,600)	(155,072)	(188,535)	(148,123)
Restructuring costs	(14,000)	(13,000)	(8,800)	(13,000)	(91,900)	(20,300)	(31,200)	(44,900)	(48,840)	(188,345)	(95,446)
Gain on disposal activities											3,590
Impairment of long-lived assets											(24,900)
Operating income	170,300	$ 160,500	$ 157,600	$ 141,200	65,300	$ 118,900	$ 110,100	$ 87,200	629,553	381,461	396,096
Segment assets	11,733,954				12,998,951				11,733,954	12,998,951
Total
Summarized financial information concerning the Company's reportable segments
Revenue									13,340,900	13,240,000	13,642,500
Gross profit									798,400	709,600	611,700
Equity in earnings of joint ventures									35,000	48,800	49,300
General and administrative expenses									(155,000)	(188,600)	(148,200)
Restructuring costs									(48,800)	(188,300)	(95,400)
Gain on disposal activities											3,600
Impairment of long-lived assets											(24,900)
Operating income									$ 629,600	$ 381,500	$ 396,100
Gross profit as a % of revenue									6.00%	(5.40%)	4.50%
Corporate
Summarized financial information concerning the Company's reportable segments
General and administrative expenses									$ (143,900)	$ (180,000)	$ (143,200)
Restructuring costs									(48,800)	(188,300)	(95,400)
Impairment of long-lived assets											(9,700)
Operating income									(192,700)	(368,300)	(248,300)
Segment assets	1,390,900				1,625,800				1,390,900	1,625,800	718,400
Americas
Summarized financial information concerning the Company's reportable segments
Revenue									10,226,300	10,131,500	10,382,600
Gross profit									631,600	580,500	511,500
Equity in earnings of joint ventures									11,400	19,800	17,700
Impairment of long-lived assets											(10,800)
Operating income									643,000	600,300	518,400
Segment assets	7,204,600				8,104,400				$ 7,204,600	$ 8,104,400	$ 7,437,300
Gross profit as a % of revenue									6.20%	(5.70%)	4.90%
International
Summarized financial information concerning the Company's reportable segments
Revenue									$ 3,112,600	$ 3,101,700	$ 3,251,700
Gross profit									164,800	122,200	91,900
Equity in earnings of joint ventures									12,200	14,300	13,900
Gain on disposal activities											3,600
Impairment of long-lived assets											(4,400)
Operating income									177,000	136,500	105,000
Segment assets	2,764,500				2,454,000				$ 2,764,500	$ 2,454,000	$ 2,247,100
Gross profit as a % of revenue									5.30%	(3.90%)	2.80%
AECOM Capital
Summarized financial information concerning the Company's reportable segments
Revenue									$ 2,000	$ 6,800	$ 8,200
Gross profit									2,000	6,900	8,300
Equity in earnings of joint ventures									11,400	14,700	17,700
General and administrative expenses									(11,100)	(8,600)	(5,000)
Operating income									2,300	13,000	21,000
Segment assets	$ 234,600				$ 198,000				$ 234,600	$ 198,000	$ 197,800

Reportable Segments and Geogr_4

Reportable Segments and Geographic Information - Geographic Information (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Geographic Information
Long-Lived Assets	$ 5,200.1	$ 4,984.3	$ 4,410.3
Americas
Geographic Information
Long-Lived Assets	3,922.8	3,733.2	3,399.1
Europe, Middle East, Africa
Geographic Information
Long-Lived Assets	872.3	875.8	738.8
Asia Pacific
Geographic Information
Long-Lived Assets	$ 405	$ 375.3	$ 272.4

Major Clients (Details)

Major Clients (Details) - Revenue - Customer Concentration Risk	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Percentage of total revenue
Period for which criteria of threshold percentage for disclosure not met in past	5 years
Maximum
Percentage of total revenue
Percentage of revenue accounted for by no other single client (as a percent)	10.00%
Agencies of U.S. Federal Government
Percentage of total revenue
Concentration (as a percent)	8.00%	8.00%	9.00%

Quarterly Financial Informati_3

Quarterly Financial Information-Unaudited (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Quarterly Financial Information-Unaudited
Revenue	$ 3,353,800	$ 3,408,400	$ 3,265,500	$ 3,313,200	$ 3,569,000	$ 3,189,700	$ 3,245,700	$ 3,235,600	$ 13,340,852	$ 13,239,976	$ 13,642,455
Cost of revenue	3,136,600	3,206,800	3,070,300	3,128,800	3,379,100	3,004,600	3,076,900	3,069,800	12,542,431	12,530,416	13,030,800
Gross profit	217,200	201,600	195,200	184,400	189,900	185,100	168,800	165,800	798,421	709,560	611,655
Equity in earnings of joint ventures	11,400	8,200	7,200	8,200	16,800	8,600	13,500	9,900	35,044	48,781	49,320
General and administrative expenses	(44,300)	(36,300)	(36,000)	(38,400)	(49,500)	(54,500)	(41,000)	(43,600)	(155,072)	(188,535)	(148,123)
Restructuring costs	(14,000)	(13,000)	(8,800)	(13,000)	(91,900)	(20,300)	(31,200)	(44,900)	(48,840)	(188,345)	(95,446)
Impairment of long-lived assets											(24,900)
Gain on disposal activities											3,590
Income from operations	170,300	160,500	157,600	141,200	65,300	118,900	110,100	87,200	629,553	381,461	396,096
Other income	5,700	4,500	3,500	3,900	1,600	3,100	2,400	4,000	17,603	11,056	14,556
Interest expense	(25,900)	(149,000)	(32,800)	(30,700)	(47,500)	(35,000)	(37,100)	(40,400)	(238,352)	(159,914)	(161,482)
Income from continuing operations before taxes	150,100	16,000	128,300	114,400	19,400	87,000	75,400	50,800	408,804	232,603	249,170
Income tax expense (benefit) for continuing operations	46,100	(17,800)	35,100	25,600	15,300	(7,200)	21,700	15,900	89,011	45,753	13,498
Net income from continuing operations	104,000	33,800	93,200	88,800	4,100	94,200	53,700	34,900	319,793	186,850	235,672
Net loss from discontinued operations	2,300	(15,400)	(47,900)	(55,800)	(228,000)	(100)	(130,700)	18,200	(116,813)	(340,591)	(419,662)
Net income (loss)	106,300	18,400	45,300	33,000	(223,900)	94,100	(77,000)	53,100	202,980	(153,741)	(183,990)
Net income attributable to noncontrolling interests from continuing operations	(8,900)	(5,900)	(4,900)	(5,400)	(4,200)	(3,100)	(5,200)	(4,000)
Net income attributable to noncontrolling interests from discontinued operations	1,200	1,000	1,000	1,500	(2,200)	(1,600)	(3,900)	(8,500)
Net income attributable to noncontrolling interests	(10,100)	(6,900)	(5,900)	(6,900)	(6,400)	(4,700)	(9,100)	(12,500)	(29,795)	(32,629)	(77,060)
Net income (loss) attributable to AECOM from continuing operations	95,100	27,900	88,300	83,400	(100)	91,100	48,500	30,900	294,684	170,452	210,962
Net income (loss) attributable to AECOM from discontinued operations	1,100	(16,400)	(48,900)	(57,300)	(230,200)	(1,700)	(134,600)	9,700	(121,499)	(356,822)	(472,012)
Net income (loss) attributable to AECOM	$ 96,200	$ 11,500	$ 39,400	$ 26,100	$ (230,300)	$ 89,400	$ (86,100)	$ 40,600	$ 173,185	$ (186,370)	$ (261,050)
Net income attributable to AECOM per share:
Basic continuing operations per share	$ 0.66	$ 0.19	$ 0.60	$ 0.55		$ 0.57	$ 0.31	$ 0.20	$ 2	$ 1.07	$ 1.34
Basic discontinued operations per share	0.01	(0.11)	(0.33)	(0.38)	$ (1.44)	(0.01)	(0.85)	0.06	(0.82)	(2.24)	(3)
Basic earnings per share	0.67	0.08	0.27	0.17	(1.44)	0.56	(0.54)	0.26	1.18	(1.17)	(1.66)
Earnings Per Share, Diluted [Abstract]
Diluted continuing operations per share	0.65	0.19	0.59	0.54		0.56	0.30	0.19	1.97	1.06	1.32
Diluted discontinued operations per share	0.01	(0.11)	(0.33)	(0.37)	(1.44)	(0.01)	(0.84)	0.06	(0.81)	(2.22)	(2.95)
Diluted earnings per share	$ 0.66	$ 0.08	$ 0.26	$ 0.17	$ (1.44)	$ 0.55	$ (0.54)	$ 0.25	$ 1.16	$ (1.16)	$ (1.63)
Weighted average shares outstanding:
Basic	143,800	146,100	147,800	151,400	160,000	160,100	158,600	157,300	147,279	159,005	157,044
Diluted	146,600	148,900	149,500	153,700	160,000	161,800	160,700	160,600	149,676	161,292	159,684

Schedule II_ Valuation and Qu_2

Schedule II: Valuation and Qualifying Accounts (Details) - Allowance for Doubtful Accounts - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Changes in valuation and qualifying accounts
Balance at Beginning of Year	$ 77.9	$ 56.5	$ 54.2
Additions Charged to Cost of Revenue	29.1	37.6	23.9
Deductions	(14.9)	(16.4)	(21)
Other and Foreign Exchange Impact	0.7	0.2	(0.6)
Balance at the End of the Year	$ 92.8	$ 77.9	$ 56.5