AECOM (ACM) 10-K 19 Nov 24 2024 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Sep. 30, 2024	Nov. 15, 2024	Mar. 29, 2024
Document and Entity Information
Document Type	10-K
Document Annual Report	true
Document Period End Date	Sep. 30, 2024
Document Transition Report	false
Entity File Number	000-52423
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
Title of 12(b) Security	Common Stock, $0.01 par value
Trading Symbol	ACM
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
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
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		132,463,704
Entity Public Float			$ 13.3
Entity Central Index Key	0000868857
Current Fiscal Year End Date	--09-30
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	FY
Amendment Flag	false
Auditor Name	Ernst & Young LLP
Auditor Firm ID	42
Auditor Location	Los Angeles, California

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023
CURRENT ASSETS:
Cash and cash equivalents	$ 1,316,945	$ 1,030,447
Cash in consolidated joint ventures	263,932	229,759
Total cash and cash equivalents	1,580,877	1,260,206
Accounts receivable-net	2,793,307	2,544,453
Contract assets	1,806,458	1,525,051
Prepaid expenses and other current assets	758,693	730,145
Current assets held for sale	77,224	95,221
Income taxes receivable	159,500	14,435
TOTAL CURRENT ASSETS	7,176,059	6,169,511
PROPERTY AND EQUIPMENT-NET	354,377	382,638
DEFERRED TAX ASSETS-NET	326,685	439,604
INVESTMENTS IN UNCONSOLIDATED JOINT VENTURES	138,067	139,236
GOODWILL	3,480,155	3,418,930
INTANGIBLE ASSETS-NET	6,932	17,769
OTHER NON-CURRENT ASSETS	147,228	218,666
OPERATING LEASE RIGHT-OF-USE ASSETS	432,166	447,044
TOTAL ASSETS	12,061,669	11,233,398
CURRENT LIABILITIES:
Short-term debt	3,080	3,085
Accounts payable	2,560,122	2,190,755
Accrued expenses and other current liabilities	2,385,731	2,287,546
Income taxes payable	27,418	48,161
Contract liabilities	1,298,327	1,188,742
Current liabilities held for sale	35,559	45,625
Current portion of long-term debt	63,844	86,369
TOTAL CURRENT LIABILITIES	6,374,081	5,850,283
OTHER LONG-TERM LIABILITIES	156,406	123,846
OPERATING LEASE LIABILITIES, NON-CURRENT	510,573	548,851
LONG-TERM LIABILITIES HELD FOR SALE		792
DEFERRED TAX LIABILITY-NET	27,509	16,960
PENSION BENEFIT OBLIGATIONS	172,360	195,586
LONG-TERM DEBT	2,450,330	2,113,369
TOTAL LIABILITIES	9,691,259	8,849,687
COMMITMENTS AND CONTINGENCIES (Note 18)
AECOM STOCKHOLDERS' EQUITY:
Common stock-authorized, 300,000,000 shares of $0.01 par value as of September 30, 2024 and 2023; issued and outstanding 132,552,407 and 136,210,883 shares as of September 30, 2024 and 2023, respectively	1,326	1,362
Additional paid-in capital	4,347,197	4,241,523
Accumulated other comprehensive loss	(882,671)	(926,577)
Accumulated deficits	(1,281,647)	(1,103,976)
TOTAL AECOM STOCKHOLDERS' EQUITY	2,184,205	2,212,332
Noncontrolling interests	186,205	171,379
TOTAL STOCKHOLDERS' EQUITY	2,370,410	2,383,711
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 12,061,669	$ 11,233,398

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2024	Sep. 30, 2023
Consolidated Balance Sheets
Common stock, authorized shares (in shares)	300,000,000	300,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, issued shares (in shares)	132,552,407	136,210,883
Common stock, outstanding shares (in shares)	132,552,407	136,210,883

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Consolidated Statements of Operations
Revenue	$ 16,105,498	$ 14,378,461	$ 13,148,182
Cost of revenue	15,021,157	13,432,996	12,300,208
Gross profit	1,084,341	945,465	847,974
Equity in (losses) earnings of joint ventures	2,124	(279,352)	53,640
General and administrative expenses	(160,105)	(153,575)	(147,309)
Restructuring costs	(98,918)	(188,404)	(107,501)
Income from operations	827,442	324,134	646,804
Other income	17,570	8,357	5,942
Interest income	58,560	40,251	8,210
Interest expense	(185,420)	(159,342)	(110,274)
Income from continuing operations before taxes	718,152	213,400	550,682
Income tax expense for continuing operations	152,900	56,052	136,051
Net income from continuing operations	565,252	157,348	414,631
Net loss from discontinued operations	(104,997)	(57,207)	(79,929)
Net income	460,255	100,141	334,702
Net income attributable to noncontrolling interests from continuing operations	(59,322)	(43,262)	(25,521)
Net income (loss) attributable to noncontrolling interests from discontinued operations	1,333	(1,547)	1,430
Net income attributable to noncontrolling interests	(57,989)	(44,809)	(24,091)
Net income attributable to AECOM from continuing operations	505,930	114,086	389,110
Net loss attributable to AECOM from discontinued operations	(103,664)	(58,754)	(78,499)
Net income attributable to AECOM	$ 402,266	$ 55,332	$ 310,611
Net income (loss) attributable to AECOM per share:
Basic continuing operations per share	$ 3.73	$ 0.82	$ 2.76
Basic discontinued operations per share	(0.76)	(0.42)	(0.55)
Basic earnings per share	2.97	0.40	2.21
Diluted continuing operations per share	3.71	0.81	2.73
Diluted discontinued operations per share	(0.76)	(0.42)	(0.55)
Diluted earnings per share	$ 2.95	$ 0.39	$ 2.18
Weighted average shares outstanding:
Basic (in shares)	135,544	138,614	140,768
Diluted (in shares)	136,453	140,109	142,696

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Consolidated Statements of Comprehensive Income
Net income	$ 460,255	$ 100,141	$ 334,702
Other comprehensive (loss) income, net of tax:
Net unrealized (loss) gain on derivatives, net of tax	(23,290)	2,165	41,002
Foreign currency translation adjustments	93,389	59,720	(220,043)
Pension adjustments, net of tax	(25,986)	(8,719)	98,893
Other comprehensive income (loss), net of tax	44,113	53,166	(80,148)
Comprehensive income, net of tax	504,368	153,307	254,554
Noncontrolling interests in comprehensive income of consolidated subsidiaries, net of tax	(58,196)	(44,877)	(23,241)
Comprehensive income attributable to AECOM, net of tax	$ 446,172	$ 108,430	$ 231,313

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Parent Cumulative Effect, Period of Adoption, Adjustment	Parent	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficits Cumulative Effect, Period of Adoption, Adjustment	Accumulated Deficits	Non-Controlling Interest	Cumulative Effect, Period of Adoption, Adjustment	Total
BALANCE at Sep. 30, 2021		$ 2,712,470	$ 1,432	$ 4,115,541	$ (900,377)		$ (504,126)	$ 117,107		$ 2,829,577
Increase (Decrease) in Stockholders' Equity
Net income		310,611					310,611	24,091		334,702
Dividends declared	$ (85,260)					$ (85,260)			$ (85,260)
Other comprehensive loss		(79,298)			(79,298)			(850)		(80,148)
Issuance of stock		52,630	25	52,605						52,630
Repurchases of stock		(472,970)	(68)	(50,023)			(422,879)			(472,970)
Stock-based compensation		38,471		38,471						38,471
Other transactions with noncontrolling interests								772		772
Contributions from noncontrolling interests								185		185
Distributions to noncontrolling interests								(12,580)		(12,580)
BALANCE at Sep. 30, 2022		2,476,654	1,389	4,156,594	(979,675)		(701,654)	128,725		2,605,379
Increase (Decrease) in Stockholders' Equity
Net income		55,332					55,332	44,809		100,141
Dividends declared		(100,872)					(100,872)			(100,872)
Other comprehensive loss		53,098			53,098			68		53,166
Issuance of stock		64,983	19	64,964						64,983
Repurchases of stock		(382,745)	(46)	(25,917)			(356,782)			(382,745)
Stock-based compensation		45,882		45,882						45,882
Contributions from noncontrolling interests								17,225		17,225
Distributions to noncontrolling interests								(19,448)		(19,448)
BALANCE at Sep. 30, 2023		2,212,332	1,362	4,241,523	(926,577)		(1,103,976)	171,379		2,383,711
Increase (Decrease) in Stockholders' Equity
Net income		402,266					402,266	57,989		460,255
Dividends declared		(120,454)					(120,454)			(120,454)
Other comprehensive loss		43,906			43,906			207		44,113
Issuance of stock		65,385	16	65,369						65,385
Repurchases of stock		(480,750)	(52)	(21,215)			(459,483)			(480,750)
Stock-based compensation		61,520		61,520						61,520
Contributions from noncontrolling interests								13,508		13,508
Distributions to noncontrolling interests								(56,878)		(56,878)
BALANCE at Sep. 30, 2024		$ 2,184,205	$ 1,326	$ 4,347,197	$ (882,671)		$ (1,281,647)	$ 186,205		$ 2,370,410

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 460,255	$ 100,141	$ 334,702
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	178,812	175,725	170,886
Equity in losses (earnings) of unconsolidated joint ventures	1,276	282,291	(46,303)
Distribution of earnings from unconsolidated joint ventures	24,254	41,178	27,175
Non-cash stock compensation	61,520	45,882	38,471
Impairment of long-lived assets		86,199
Loss on sale of discontinued operations	90,412	43,222	48,095
Foreign currency translation	15,468	969	(31,529)
Deferred income tax expense (benefit)	150,894	(135,878)	22,821
Other	(4,854)	6,388	15,295
Changes in operating assets and liabilities:
Accounts receivable and contract assets	(500,798)	(402,498)	236,605
Prepaid expenses and other assets	(207,359)	131,903	132,003
Accounts payable	391,176	169,514	(102,873)
Accrued expenses and other current liabilities	91,983	97,239	48,019
Contract liabilities	109,390	137,484	(7,434)
Other long-term liabilities	(34,939)	(83,779)	(172,297)
Net cash provided by operating activities	827,490	695,980	713,636
CASH FLOWS FROM INVESTING ACTIVITIES:
Payment for business acquisition, net of cash required	(18,658)
Payments for sale of discontinued operations, net of cash disposed			(42,261)
Investment in unconsolidated joint ventures	(55,058)	(59,772)	(26,672)
Return of investment in unconsolidated joint ventures		20,874	11,723
Proceeds from sale of investments	3,180	5,977	10,242
Other investing activities	(21,000)
Proceeds from disposal of property and equipment	494	344	8,951
Payments for capital expenditures	(119,597)	(105,600)	(137,017)
Net cash used in by investing activities	(210,639)	(138,177)	(175,034)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from borrowings under credit agreements	6,169,266	3,506,668	3,618,585
Repayments of borrowings under credit agreements	(5,878,475)	(3,552,639)	(3,657,308)
Cash paid for debt issuance costs	(16,573)		(155)
Dividends paid	(115,244)	(96,192)	(63,288)
Proceeds from issuance of common stock	34,556	32,897	26,666
Proceeds from exercise of stock options	2,056	6,168
Payments to repurchase common stock	(478,501)	(379,284)	(472,970)
Net distributions to noncontrolling interests	(16,177)	(2,223)	(12,395)
Other financing activities	3,632	11,670	(27,450)
Net cash used in financing activities	(295,460)	(472,935)	(588,315)
EFFECT OF EXCHANGE RATE CHANGES ON CASH	1,319	512	(8,307)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	322,710	85,380	(58,020)
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	1,262,152	1,176,772	1,234,792
CASH AND CASH EQUIVALENTS AT END OF YEAR	1,584,862	1,262,152	1,176,772
LESS: CASH AND CASH EQUIVALENTS INCLUDED IN CURRENT ASSETS HELD FOR SALE	(3,985)	(1,946)	(4,563)
CASH AND CASH EQUIVALENTS OF CONTINUING OPERATIONS AT END OF YEAR	1,580,877	1,260,206	1,172,209
SUPPLEMENTAL CASH FLOW INFORMATION:
Interest paid	(177,450)	(153,975)	(104,644)
Net income taxes paid	$ (139,972)	$ (78,448)	$ (104,742)

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Sep. 30, 2024
Significant Accounting Policies
Significant Accounting Policies	AECOM NOTES TO CONSOLIDATED FINANCIAL STATEMENTS 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. Goodwill is evaluated for impairment either by assessing qualitative factors or by performing a quantitative assessment. Qualitative factors, such as overall financial performance, industry or market considerations, or other relevant events, are assessed to determine if it is more likely than not that the fair value of the reporting units is less than their carrying amounts. During a quantitative 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 On December 22, 2017, the United States enacted the Tax Cuts and Jobs Act, which significantly changed U.S. tax law and included a provision to tax global intangible low-taxed income (GILTI) of foreign subsidiaries. The Company recognizes taxes due under the GILTI provision as a current period expense.

New Accounting Pronouncements a

New Accounting Pronouncements and Changes in Accounting	12 Months Ended
	Sep. 30, 2024
New Accounting Pronouncements and Changes in Accounting
New Accounting Pronouncements and Changes in Accounting	2. New Accounting Pronouncements and Changes in Accounting In November 2023, the Financial Accounting Standards Board (FASB) amended the guidance of Accounting Standards Codification (ASC) 280, Segment Reporting In December 2023, the FASB issued ASU 2023-09, Income Taxes ​

Discontinued Operations, Goodwi

Discontinued Operations, Goodwill, and Intangible Assets	12 Months Ended
	Sep. 30, 2024
Discontinued Operations, Goodwill, and Intangible Assets
Discontinued Operations, Goodwill, and Intangible Assets	3. Discontinued Operations, Goodwill, and Intangible Assets In the first quarter of fiscal 2020, management approved a plan to dispose of via sale the Company’s self-perform at-risk construction businesses. 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 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 would have a major effect on the Company’s operations and financial results and qualified for presentation as discontinued operations in accordance with FASB ASC 205-20. Accordingly, the financial results of the self-perform at-risk construction businesses are presented in the Consolidated Statement 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. The Company completed the sale of its power and oil and gas construction businesses in fiscal 2021 and fiscal 2022, respectively. The Company completed the sale of its civil infrastructure construction business to affiliates of Oroco Capital in the second quarter of fiscal 2021. In the second quarters of both fiscal 2024 and 2023, the Company recorded losses related to revised estimates of its contingent consideration receivable recognized in its civil infrastructure construction business of $103.1 million and $38.9 million, respectively. During the third quarter of fiscal 2024, the Company resolved contingencies related to the sale of its civil infrastructure construction business and received equity in the counterparty, and the Company recorded a $12.7 million gain based on the fair value of the equity received. Concurrently, the Company participated as a member of a lending group in a revolving credit facility for the counterparty, committing to fund $30 million that matures in May 2029. As of September 30, 2024, the Company has funded $21.0 million, all of which was classified as a cash outflow in other investing activities and outstanding. The following table represents summarized balance sheet information of assets and liabilities held for sale (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ September 30, ​ 2024 2023 ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ $ 4.0 ​ $ 1.9 Receivables and contract assets ​ 73.2 ​ ​ 93.3 Current assets held for sale ​ $ 77.2 ​ $ 95.2 ​ ​ ​ ​ ​ ​ ​ Property and equipment, net ​ $ 16.7 ​ $ 14.2 Other ​ 1.2 ​ ​ — Write-down of assets to fair value less cost to sell ​ ​ (17.9) ​ ​ (14.2) Non-current assets held for sale ​ $ — ​ $ — ​ ​ ​ ​ ​ ​ ​ Accounts payable and accrued expenses ​ $ 35.6 ​ $ 45.6 Current liabilities held for sale ​ $ 35.6 ​ $ 45.6 ​ ​ ​ ​ ​ ​ ​ Long-term liabilities held for sale ​ $ — ​ $ 0.8 ​ The following table represents summarized income statement information of discontinued operations (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, ​ September 30, September 30, ​ 2024 2023 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenue ​ $ 178.2 ​ $ 212.8 ​ $ 347.4 Cost of revenue ​ ​ 181.1 ​ ​ 223.2 ​ ​ 360.2 Gross loss ​ ​ (2.9) ​ ​ (10.4) ​ ​ (12.8) Equity in earnings of joint ventures ​ ​ (3.4) ​ ​ (2.9) ​ ​ (7.4) Loss on disposal activities ​ ​ (97.1) ​ ​ (50.6) ​ ​ (48.1) Transaction costs ​ ​ (0.2) ​ ​ (0.2) ​ ​ (9.7) Loss from operations ​ ​ (103.6) ​ ​ (64.1) ​ ​ (78.0) Other loss ​ ​ (1.5) ​ ​ (1.0) ​ ​ — Interest expense ​ ​ — ​ ​ — ​ ​ (0.1) Loss before taxes ​ ​ (105.1) ​ ​ (65.1) ​ ​ (78.1) Income tax (benefit) expense ​ ​ (0.1) ​ ​ (7.9) ​ ​ 1.8 Net loss from discontinued operations ​ $ (105.0) ​ $ (57.2) ​ $ (79.9) ​ 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, September 30, ​ 2024 2023 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Payments for capital expenditures ​ $ (2.5) ​ $ (6.2) ​ $ (2.7) ​ The Company also recorded a $12.7 million non-cash gain in discontinued operations in fiscal 2024. The changes in the carrying value of goodwill by reportable segment for the year ended September 30, 2024 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ Exchange ​ ​ ​ ​ September 30, ​ 2023 Impact Acquired 2024 ​ ​ (in millions) Americas ​ $ 2,614.0 ​ $ 0.6 ​ $ 11.1 ​ $ 2,625.7 International ​ 804.9 ​ ​ 49.6 ​ ​ — ​ ​ 854.5 Total ​ $ 3,418.9 ​ $ 50.2 ​ $ 11.1 ​ $ 3,480.2 ​ The gross amounts and accumulated amortization of the Company’s acquired identifiable intangible assets with finite useful lives as of September 30, 2024 and 2023, included in intangible assets—net, in the accompanying consolidated balance sheets, were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2024 ​ September 30, 2023 ​ ​ ​ ​ Gross ​ Accumulated ​ Intangible ​ Gross ​ Accumulated ​ Intangible ​ Amortization ​ Amount Amortization Assets, Net Amount Amortization Assets, Net Period ​ ​ (in millions) ​ (years) Backlog and Customer relationships ​ $ 671.7 ​ $ (664.8) ​ $ 6.9 ​ $ 663.8 ​ $ (646.0) ​ $ 17.8 ​ 1 - 11 ​ Amortization expense of acquired intangible assets included within cost of revenue was $18.8 million and $18.6 million for the years ended September 30, 2024 and 2023, respectively. The following table presents estimated amortization expense of existing intangible assets for the succeeding years: ​ ​ ​ ​ ​ Fiscal Year (in millions) 2025 ​ $ 2.1 2026 ​ ​ 1.5 2027 ​ 1.5 2028 ​ 1.5 2029 ​ ​ 0.3 Total ​ $ 6.9 ​

Revenue Recognition

Revenue Recognition	12 Months Ended
	Sep. 30, 2024
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, which it believes to be the best measure of progress towards completion of the performance obligation. 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, 2024, 2023 and 2022 were $8.9 billion, $7.7 billion and $6.8 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 as the Company believes this is the best measure of progress towards completion. The following tables present the Company’s revenues disaggregated by revenue sources: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, ​ September 30, ​ September 30, ​ 2024 2023 2022 ​ (in millions) Cost reimbursable ​ $ 6,361.4 ​ $ 6,128.8 ​ $ 5,454.9 Guaranteed maximum price ​ ​ 6,030.0 ​ 4,887.7 ​ 4,325.0 Fixed price ​ ​ 3,714.1 ​ 3,362.0 ​ 3,368.3 Total revenue ​ $ 16,105.5 ​ $ 14,378.5 ​ $ 13,148.2 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, ​ September 30, ​ September 30, ​ 2024 2023 2022 ​ (in millions) Americas ​ $ 12,487.0 ​ $ 10,976.4 ​ $ 9,941.6 Europe, Middle East, India, Africa ​ ​ 2,141.5 ​ 1,937.3 ​ 1,759.8 Asia-Australia-Pacific ​ ​ 1,477.0 ​ 1,464.8 ​ 1,446.8 Total revenue ​ $ 16,105.5 ​ $ 14,378.5 ​ $ 13,148.2 ​ As of September 30, 2024, the Company had allocated $19.8 billion of transaction price to unsatisfied or partially satisfied performance obligations, of which approximately 60% is expected to be satisfied within the next twelve months. The majority of the remaining performance obligation after the first 12 months is expected to be recognized over a two-year period. 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. The Company recognized revenue of $801.0 million and $1,043.7 million during the years ended September 30, 2024 and 2023, respectively, that was included in contract liabilities as of September 30, 2023 and 2022, 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 receivables 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. Net accounts receivable consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ September 30, ​ September 30, ​ ​ 2024 2023 ​ ​ (in millions) Billed ​ $ 2,184.9 ​ $ 2,122.2 Contract retentions ​ 696.3 ​ ​ 516.5 Total accounts receivable—gross ​ 2,881.2 ​ ​ 2,638.7 Allowance for doubtful accounts and credit losses ​ (87.9) ​ ​ (94.2) Total accounts receivable—net ​ $ 2,793.3 ​ $ 2,544.5 ​ Substantially all contract assets as of September 30, 2024 and September 30, 2023 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 $180 million and $160 million as of September 30, 2024 and 2023, respectively. The asset related to the Deactivation, Demolition, and Removal Project retained from the MS Purchaser as defined in 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 but nonetheless represent an unconditional right to cash. 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, 2024 and 2023. The Company sold trade receivables to financial institutions, of which $319.5 million and $291.0 million were outstanding as of September 30, 2024 and 2023, 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
	Sep. 30, 2024
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 ​ 2024 2023 (years) ​ ​ (in millions) ​ ​ ​ ​ Building and land ​ $ 10.1 ​ $ 10.4 10 - 45 Leasehold improvements ​ 299.3 ​ 329.4 1 - 20 Computer systems and equipment ​ 659.6 ​ 716.7 3 - 12 Furniture and fixtures ​ 92.2 ​ 97.9 3 - 10 Total ​ 1,061.2 ​ 1,154.4 ​ ​ ​ ​ Accumulated depreciation and amortization ​ (706.8) ​ (771.8) ​ ​ ​ ​ Property and equipment, net ​ $ 354.4 ​ $ 382.6 ​ ​ ​ ​ ​ Depreciation expense for the fiscal years ended September 30, 2024, 2023 and 2022 was $152.3 million, $152.3 million, and $147.0 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
	Sep. 30, 2024
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 - 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, ​ 2024 2023 ​ ​ (in millions) Current assets ​ $ 836.9 ​ $ 806.3 Non-current assets ​ 83.1 ​ 75.9 Total assets ​ $ 920.0 ​ $ 882.2 ​ ​ ​ ​ ​ ​ ​ Current liabilities ​ $ 763.6 ​ $ 779.6 Non-current liabilities ​ 1.5 ​ 1.5 Total liabilities ​ 765.1 ​ 781.1 Total AECOM deficit ​ (17.2) ​ (54.9) Noncontrolling interests ​ 172.1 ​ 156.0 Total owners’ equity ​ 154.9 ​ 101.1 Total liabilities and owners’ equity ​ $ 920.0 ​ $ 882.2 ​ Total revenue of the consolidated joint ventures was $2,242.8 million, $1,984.3 million, and $1,411.7 million for the years ended September 30, 2024, 2023 and 2022, 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, ​ 2024 2023 ​ ​ (in millions) Current assets ​ $ 1,379.0 ​ $ 1,177.4 Non-current assets ​ 799.9 ​ 996.3 Total assets ​ $ 2,178.9 ​ $ 2,173.7 ​ ​ ​ ​ ​ ​ ​ Current liabilities ​ $ 976.3 ​ $ 605.9 Non-current liabilities ​ 114.8 ​ 441.7 Total liabilities ​ 1,091.1 ​ 1,047.6 Joint ventures’ equity ​ 1,087.8 ​ 1,126.1 Total liabilities and joint ventures’ equity ​ $ 2,178.9 ​ $ 2,173.7 ​ ​ ​ ​ ​ ​ ​ AECOM’s investment in joint ventures ​ $ 138.1 ​ $ 139.2 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Twelve Months Ended ​ ​ September 30, ​ September 30, ​ 2024 2023 ​ ​ (in millions) Revenue ​ $ 2,145.8 ​ $ 1,248.2 Cost of revenue ​ 1,972.1 ​ 1,170.7 Gross profit ​ $ 173.7 ​ $ 77.5 Net income ​ $ 168.6 ​ $ 72.9 ​ Summary of AECOM’s equity in earnings of unconsolidated joint ventures is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ ​ September 30, ​ September 30, ​ September 30, ​ ​ 2024 2023 2022 ​ ​ (in millions) ​ Pass-through joint ventures ​ $ 29.0 ​ $ 24.5 ​ $ 29.2 ​ Other joint ventures ​ (26.9) ​ (303.9) ​ 24.4 ​ Total ​ $ 2.1 ​ $ (279.4) ​ $ 53.6 ​ ​ The Company completed a transaction that transitioned the AECOM Capital team to a new third-party platform in the third quarter of fiscal 2024. The team will continue to support AECOM Capital’s investment vehicles pursuant to certain advisory agreements in a manner consistent with their current obligations. During the third quarter of fiscal 2023, the Company identified indicators of impairment in the equity method investments held in its AECOM Capital segment. Specifically, the Company identified evidence that the carrying value of certain of the investments in its real estate portfolio were in excess of their fair values. The Company concluded it no longer had the intent to retain certain of these investments for a period of time sufficient to allow for an anticipated recovery in market value. In the third quarter of fiscal 2023, the Company recorded an impairment loss of $307.0 million to reduce the carrying value of these investments to their estimated fair values. During the first quarter of fiscal 2024, the Company recorded an additional impairment loss of $35.9 million. These impairments do not relate to investments in respect of which affiliates of AECOM Capital provide advisory services or manage third party capital. AECOM Capital will continue to manage existing investment vehicles and investments in a manner consistent with their current obligations. Fair value was determined using Level 3 inputs such as forecasted cash flows and comparable sales prices.

Pension Benefit Obligations

Pension Benefit Obligations	12 Months Ended
	Sep. 30, 2024
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, ​ ​ 2024 ​ 2023 ​ 2022 ​ U.S. Int’l U.S. Int’l U.S. Int’l ​ ​ (in millions) Change in benefit obligation: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Benefit obligation at beginning of year ​ $ 181.2 ​ $ 756.2 ​ $ 198.1 ​ $ 791.2 ​ $ 265.4 ​ $ 1,470.8 Service cost ​ — ​ 0.2 ​ — ​ 0.3 ​ — ​ 0.5 Participant contributions ​ 0.1 ​ 0.3 ​ 0.1 ​ 0.2 ​ 0.1 ​ 0.3 Interest cost ​ 9.7 ​ 43.7 ​ 9.8 ​ 47.7 ​ 4.7 ​ 24.1 Benefits and expenses paid ​ (17.6) ​ (47.7) ​ (17.2) ​ (42.2) ​ (18.4) ​ (44.3) Actuarial loss (gain) ​ 13.5 ​ 37.0 ​ (8.8) ​ (112.5) ​ (51.9) ​ (458.1) Plan settlements ​ — ​ (3.2) ​ (1.5) ​ (1.5) ​ (1.8) ​ (2.2) Transfers in ​ ​ — ​ ​ — ​ ​ 0.7 ​ ​ — ​ ​ — ​ ​ — Foreign currency translation (gain) loss ​ — ​ 73.9 ​ — ​ 73.0 ​ — ​ (199.9) Benefit obligation at end of year ​ $ 186.9 ​ $ 860.4 ​ $ 181.2 ​ $ 756.2 ​ $ 198.1 ​ $ 791.2 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, ​ September 30, ​ September 30, ​ ​ 2024 ​ 2023 ​ 2022 ​ 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 ​ $ 98.8 ​ $ 673.3 ​ $ 101.4 ​ $ 683.5 ​ $ 138.9 ​ $ 1,251.8 Actual return on plan assets ​ 15.8 ​ ​ 89.0 ​ 7.8 ​ (54.2) ​ (27.2) ​ (374.5) Employer contributions ​ 11.9 ​ ​ 25.1 ​ 8.2 ​ 24.8 ​ 9.8 ​ 23.6 Participant contributions ​ 0.1 ​ ​ 0.3 ​ 0.1 ​ 0.2 ​ 0.1 ​ 0.3 Benefits and expenses paid ​ (17.6) ​ ​ (47.7) ​ (17.2) ​ (42.2) ​ (18.4) ​ (44.3) Plan settlements ​ — ​ ​ (3.2) ​ (1.5) ​ (1.5) ​ (1.8) ​ (2.2) Foreign currency translation (loss) gain ​ — ​ ​ 67.5 ​ — ​ 62.7 ​ — ​ (171.2) Fair value of plan assets at end of year ​ $ 109.0 ​ $ 804.3 ​ $ 98.8 ​ $ 673.3 ​ $ 101.4 ​ $ 683.5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, 2024 ​ September 30, 2023 ​ September 30, 2022 ​ U.S. Int’l U.S. Int’l U.S. Int’l ​ ​ (in millions) Reconciliation of funded status: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Funded status at end of year ​ $ (77.9) ​ $ (56.1) ​ $ (82.4) ​ $ (82.9) ​ $ (96.7) ​ $ (107.7) Contribution made after measurement date ​ N/A ​ ​ N/A ​ N/A ​ N/A ​ N/A ​ N/A Net amount recognized at end of year ​ $ (77.9) ​ $ (56.1) ​ $ (82.4) ​ $ (82.9) ​ $ (96.7) ​ $ (107.7) ​ The following table sets forth the amounts recognized in the consolidated balance sheets as of September 30, 2024, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, 2024 ​ September 30, 2023 ​ September 30, 2022 ​ 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 ​ $ — ​ $ 46.6 ​ $ — ​ $ 38.7 ​ $ — ​ $ 36.8 Accrued expenses and other current liabilities ​ (8.3) ​ ​ — ​ (8.4) ​ — ​ (8.6) ​ — Pension benefit obligations ​ (69.6) ​ ​ (102.7) ​ (74.0) ​ (121.6) ​ (88.1) ​ (144.5) Net amount recognized in the balance sheet ​ $ (77.9) ​ $ (56.1) ​ $ (82.4) ​ $ (82.9) ​ $ (96.7) ​ $ (107.7) ​ The following table details the reconciliation of amounts in the consolidated statements of stockholders’ equity for the fiscal years ended September 30, 2024, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, 2024 ​ September 30, 2023 ​ September 30, 2022 ​ 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 ​ $ (0.1) ​ $ (1.3) ​ $ (0.1) ​ $ (1.2) ​ $ (0.1) ​ $ (1.2) Net loss ​ (77.6) ​ ​ (234.9) ​ ​ (77.5) ​ ​ (207.1) ​ ​ (91.7) ​ ​ (187.1) Total recognized in accumulated other comprehensive loss ​ $ (77.7) ​ $ (236.2) ​ $ (77.6) ​ $ (208.3) ​ $ (91.8) ​ $ (188.3) ​ The components of net periodic benefit cost other than the service cost component are included in other income 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, 2024, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, 2024 ​ September 30, 2023 ​ September 30, 2022 ​ U.S. Int’l U.S. Int’l U.S. Int’l ​ ​ (in millions) Components of net periodic benefit cost: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Service costs ​ $ — ​ $ 0.2 ​ $ — ​ $ 0.3 ​ $ — ​ $ 0.5 Interest cost on projected benefit obligation ​ 9.7 ​ ​ 43.7 ​ ​ 9.8 ​ ​ 47.7 ​ ​ 4.7 ​ ​ 24.1 Expected return on plan assets ​ (5.5) ​ ​ (57.4) ​ ​ (5.8) ​ ​ (60.8) ​ ​ (5.6) ​ ​ (41.4) Amortization of prior service costs ​ ​ — ​ ​ 0.1 ​ ​ — ​ ​ 0.1 ​ ​ — ​ ​ 0.1 Amortization of net loss (gain) ​ ​ 3.1 ​ ​ (2.3) ​ ​ 3.5 ​ ​ (0.6) ​ ​ 5.6 ​ ​ 6.9 Settlement loss (gain) recognized ​ ​ — ​ ​ 0.1 ​ ​ (0.1) ​ ​ 0.2 ​ ​ 0.2 ​ ​ 0.3 Net periodic benefit cost (credit) ​ $ 7.3 ​ $ (15.6) ​ $ 7.4 ​ $ (13.1) ​ $ 4.9 ​ $ (9.5) ​ 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 $2.1 million, $3.1 million, and $18.8 million in the years ended September 30, 2024, 2023 and 2022, respectively. Amounts included in accumulated other comprehensive loss as of September 30, 2024 that are expected to be recognized as components of net periodic benefit cost during fiscal 2025 are (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Int’l Amortization of prior service cost ​ $ — ​ $ (0.1) Amortization of net actuarial (losses) gain ​ (3.8) ​ 1.3 Total ​ $ (3.8) ​ $ 1.2 ​ 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, ​ ​ 2024 ​ 2023 ​ 2022 ​ U.S. Int’l U.S. Int’l U.S. Int’l ​ ​ (in millions) Projected benefit obligation ​ $ 175.1 ​ $ 649.8 ​ $ 168.8 ​ $ 628.1 ​ $ 184.8 ​ $ 601.4 Accumulated benefit obligation ​ $ 175.1 ​ $ 649.8 ​ $ 168.8 ​ $ 628.1 ​ $ 184.8 ​ $ 600.1 Fair value of plan assets ​ $ 109.0 ​ $ 547.1 ​ $ 98.8 ​ $ 506.5 ​ $ 101.4 ​ $ 456.9 ​ 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 $24.2 million to the international plans in fiscal 2025. 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 $11.2 million to U.S. plans in fiscal 2025. The table below provides the expected future benefit payments, in millions: ​ ​ ​ ​ ​ ​ ​ ​ Year Ending September 30, U.S. Int’l 2025 ​ $ 20.2 ​ $ 54.6 2026 ​ 19.5 ​ ​ 53.9 2027 ​ 18.3 ​ ​ 55.5 2028 ​ 17.7 ​ ​ 57.2 2029 ​ ​ 16.7 ​ ​ 59.2 2030-2034 ​ 71.2 ​ ​ 317.5 Total ​ $ 163.6 ​ $ 597.9 ​ The underlying assumptions for the pension plans are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, ​ September 30, ​ September 30, ​ ​ 2024 ​ 2023 ​ 2022 ​ U.S. Int’l U.S. Int’l U.S. Int’l ​ ​ (in millions) ​ Weighted-average assumptions to determine benefit obligation: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Discount rate 4.73 % 5.04 % 5.76 % 5.65 % 5.40 % 5.27 % Salary increase rate N/A ​ 2.91 % N/A ​ 3.06 % N/A ​ 3.48 % Weighted-average assumptions to determine net periodic benefit cost: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Discount rate 5.76 % 5.65 % 5.40 % 5.27 % 2.46 % 1.98 % Salary increase rate N/A ​ 3.06 % N/A ​ 3.48 % N/A ​ 3.13 % Expected long-term rate of return on plan assets 6.90 % 5.74 % 7.00 % 6.04 % 6.25 % 3.93 % ​ 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 2024 and pension plan asset allocation, both U.S. and international, as of September 30, 2024 and 2023: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Percentage of Plan Assets ​ ​ ​ ​ ​ ​ as of September 30, ​ ​ Target Allocations ​ 2024 ​ 2023 ​ U.S. Int’l U.S. Int’l U.S. Int’l Asset Category: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equities 23 % 22 % 24 % 25 % 33 % 24 % Debt 70 ​ 65 ​ 67 ​ 64 ​ 56 ​ 62 ​ Cash 3 ​ 4 ​ 4 ​ 2 ​ 2 ​ 4 ​ Diversified and other 4 ​ 9 ​ 5 ​ 9 ​ 9 ​ 10 ​ 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 6.90% and 5.74% weighted-average long-term rate of return on assets assumption for the fiscal year ended September 30, 2024 for U.S. and non-U.S. plans, respectively. As of September 30, 2024, the fair values of the Company’s pension plan assets by major asset categories were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement as of ​ ​ ​ ​ ​ ​ ​ September 30, 2024 ​ ​ ​ ​ ​ Total ​ Quoted ​ Significant ​ ​ ​ ​ ​ ​ ​ Carrying ​ Prices in ​ Other ​ Significant ​ ​ ​ ​ ​ Value as of ​ Active ​ Observable ​ Unobservable ​ Investments ​ ​ September 30, ​ Markets ​ Inputs ​ Inputs ​ measured at ​ 2024 (Level 1) (Level 2) (Level 3) NAV ​ ​ (in millions) Cash and cash equivalents ​ $ 22.1 ​ $ 22.1 ​ $ — ​ $ — ​ $ — Debt securities ​ ​ 391.5 ​ ​ 391.5 ​ ​ — ​ ​ — ​ ​ — Investment funds: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diversified and equity funds ​ 286.7 ​ ​ 48.5 ​ ​ 13.5 ​ ​ — ​ ​ 224.7 Fixed income funds ​ 213.9 ​ ​ 17.3 ​ ​ 4.1 ​ ​ — ​ ​ 192.5 Absolute return fund ​ ​ 5.9 ​ ​ — ​ ​ — ​ ​ — ​ ​ 5.9 Derivative instruments and other ​ ​ (6.8) ​ ​ 8.2 ​ ​ (15.0) ​ ​ — ​ ​ — Total ​ $ 913.3 ​ $ 487.6 ​ $ 2.6 ​ $ — ​ $ 423.1 ​ As of September 30, 2023, the fair values of the Company’s pension plan assets by major asset categories were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement as of ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2023 ​ ​ ​ ​ ​ Total ​ Quoted ​ Significant ​ ​ ​ ​ ​ ​ ​ Carrying ​ Prices in ​ Other ​ Significant ​ ​ ​ ​ ​ Value as of ​ Active ​ Observable ​ Unobservable ​ Investments ​ ​ September 30, ​ Markets ​ Inputs ​ Inputs ​ measured at ​ 2023 (Level 1) (Level 2) (Level 3) NAV ​ ​ (in millions) Cash and cash equivalents ​ $ 29.5 ​ $ 20.2 ​ $ 9.3 ​ $ — ​ $ — Debt securities ​ ​ 338.3 ​ ​ 338.3 ​ ​ — ​ ​ — ​ ​ — Investment funds: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diversified and equity funds ​ 258.4 ​ ​ 30.3 ​ ​ 13.2 ​ ​ — ​ ​ 214.9 Fixed income funds ​ 174.3 ​ ​ 21.7 ​ ​ 4.4 ​ ​ — ​ ​ 148.2 Absolute return fund ​ ​ 8.9 ​ ​ — ​ ​ — ​ ​ — ​ ​ 8.9 Derivative instruments and other ​ ​ (37.3) ​ ​ 1.5 ​ ​ (38.8) ​ ​ — ​ ​ — Total ​ $ 772.1 ​ $ 412.0 ​ $ (11.9) ​ $ — ​ $ 372.0 ​ 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. Common collective investment 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 redemption notice periods and are redeemable at the NAV, less transaction fees. 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 $2.5 million and $3.0 million for the years ended September 30, 2024 and 2023, respectively. At September 30, 2024 and 2023, none of the plans in which the Company participates are individually significant to its consolidated financial statements.

Debt

Debt	12 Months Ended
	Sep. 30, 2024
Debt
Debt	8. Debt Debt consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ September 30, ​ 2024 2023 ​ ​ (in millions) Credit Agreement ​ $ 1,446.6 ​ $ 1,119.8 2027 Senior Notes ​ ​ 997.3 ​ ​ 997.3 Other debt ​ 95.9 ​ ​ 100.2 Total debt ​ 2,539.8 ​ ​ 2,217.3 Less: Current portion of debt and short-term borrowings ​ (66.9) ​ ​ (89.5) Less: Unamortized debt issuance costs ​ ​ (22.6) ​ ​ (14.4) Long-term debt ​ $ 2,450.3 ​ $ 2,113.4 ​ The following table presents, in millions, scheduled maturities of the Company’s debt as of September 30, 2024: ​ ​ ​ ​ ​ Fiscal Year ​ ​ 2025 ​ $ 66.9 2026 ​ 27.1 2027 ​ 1,016.5 2028 ​ 9.6 2029 ​ ​ 756.8 Thereafter ​ 662.9 Total ​ $ 2,539.8 ​ Credit Agreement On April 19, 2024, the Company entered into Amendment No. 14 to Syndicated Facility Agreement (as amended, modified or otherwise supplemented, the “Credit Agreement”), pursuant to which the Company obtained a new $1,500,000,000 revolving credit facility (the “New Revolving Credit Facility”), a new $750,000,000 term loan A facility (the “New Term A Facility” and, together with the New Revolving Credit Facility, the “New Pro Rata Facilities”) and a new $700,000,000 term loan B facility (the “New Term B Facility” and, together with the New Pro Rata Facilities, the “New Credit Facilities”). The New Revolving Credit Facility and the New Term A Facility mature on April 19, 2029. The New Term B Facility matures on April 19, 2031. The New Term A Facility and the New Term B Facility were borrowed in full on April 19, 2024 in U.S. dollars. Loans under the New Revolving Credit Facility may be borrowed, and letters of credit thereunder may be issued, in U.S. dollars or in certain foreign currencies. The New Credit Facilities replace in full the Company’s existing revolving credit facility (the “Original Revolving Credit Facility”), term loan A facility and term loan B facility, and borrowings under the New Credit Facilities were used to refinance in full the Company’s existing credit facilities and for general corporate purposes. The Credit Agreement permits the Company to designate certain of its subsidiaries as additional co-borrowers from time to time. Currently, there are no co-borrowers under the New Credit Facilities. On October 29, 2024, the Company entered into Amendment No. 15 to Syndicated Facility Agreement, pursuant to which the Company reduced the interest rate spread applicable to its New Term B Facility. Borrowings under (a) the New Revolving Credit Facility (in U.S. dollars) and the New Term A Facility bear interest at a rate per annum equal to, at the Company’s option, (i) a Term SOFR rate (with a 0% floor and SOFR adjustment of 0.10%) or (ii) a base rate (with a 0% floor), in each case, plus an applicable margin of 1.225% in the case of the Term SOFR rate and 0.25% in the case of the base rate, and (b) the New Revolving Credit Facility in currencies other than U.S. dollars bear interest at a rate per annum equal to the applicable reference rate for such currency (including any related adjustments), plus an applicable margin of 1.225%. The applicable margin is subject, in each case, to adjustment based on the Company’s consolidated leverage ratio from time to time. Borrowings under the New Term B Facility, after giving effect to Amendment No. 15 to Syndicated Facility Agreement, bear interest at a rate per annum equal to, at the Company’s option, (a) a Term SOFR rate (with a 0% floor and a SOFR adjustment of 0%) or (b) a base rate (with a 0% floor), in each case, plus an applicable margin of 1.75% in the case of the Term SOFR rate and 0.75% in the case of the base rate. Certain 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 and transact with affiliates. The Company is also required to maintain 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 Covenant”). The Financial Covenant does not apply to the New Term B Facility. As of September 30, 2024, 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. At September 30, 2024 and September 30, 2023, letters of credit totaled $4.4 million and $4.4 million, respectively, under the Company’s New Revolving Credit Facility and Original Revolving Credit Facility, respectively. As of September 30, 2024 and September 30, 2023, the Company had $1,495.6 million and $1,145.6 million, respectively, available under its New Revolving Credit Facility and Original Revolving Credit Facility, respectively. 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, 2024, the estimated fair value of the 2027 Senior Notes was approximately $997.3 million. The fair value of the 2027 Senior Notes as of September 30, 2024 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 Senior 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, 2024. 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, 2024 and September 30, 2023, these outstanding standby letters of credit totaled $934.5 million and $878.9 million, respectively. As of September 30, 2024, the Company had $389.8 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 and interest rate cap agreements, during the years ended September 30, 2024, 2023 and 2022 was 5.6%, 5.3% and 3.8%, respectively. Interest expense in the consolidated statements of operations included amortization of deferred debt issuance costs for the years ended September 30, 2024, 2023 and 2022 of $7.6 million, $4.9 million and $4.9 million, respectively.

Derivative Financial Instrument

Derivative Financial Instruments and Fair Value Measurements	12 Months Ended
	Sep. 30, 2024
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 and interest rate cap agreements designated as cash flow hedges to limit exposure to 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. Depending on the type of cash flow hedge, the gain is subsequently reclassified against 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 or interest rate cap agreements would be recognized in other income. During the third quarter of fiscal 2023, the hedged debt index was changed from LIBOR to SOFR. 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, 2024 Notional Amount ​ Notional Amount ​ Fixed ​ Effective ​ Expiration Currency (in millions) Rate Date Date USD ​ ​ 400.0 ​ 1.283 % February 2023 ​ March 2028 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2023 Notional Amount ​ Notional Amount ​ Fixed ​ Effective ​ Expiration Currency (in millions) Rate Date Date USD ​ ​ 400.0 ​ 1.283 % February 2023 ​ March 2028 ​ In the fourth 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 became effective February 2023 and terminate in March 2028. By entering into the swap agreements, the Company converted a portion of the SOFR rate-based liability into a fixed rate liability. The Company will pay a fixed rate of 1.283% and receive payment at the prevailing one-month SOFR. In the third quarter of fiscal 2022, the Company purchased interest rate cap agreements with a notional value of $300.0 million to manage interest rate exposure of its variable rate loans. The caps became effective on June 30, 2022 and terminate in March 2028. The caps reduce the Company’s exposure to one-month SOFR. In the event one-month SOFR exceeds 3.465%, the Company will pay the spread between prevailing one-month SOFR and 3.465%. See Note 17 for accumulated balances and reporting period activities of derivatives related to reclassifications out of accumulated other comprehensive income for the years ended September 30, 2024, 2023 and 2022. Additionally, there were no material losses recognized in income due to amounts excluded from effectiveness testing from the Company’s interest rate swap agreements. 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, 2024, 2023 and 2022. Fair Value Measurements The fair values of the interest rate swap and interest rate cap agreements were derived by taking the net present value of the expected cash flows using observable market inputs (Level 2) such as SOFR rate curves, futures, volatilities and basis spreads (when applicable). As discussed in Note 3, The Company received an equity investment in the civil infrastructure construction business buyer and concurrently participated as a member of a lending group in a revolving credit facility. The Company elected the fair value option for its equity investment due to the availability of quoted prices of identical assets. The fair value option was also elected for the credit facility investment. Changes in fair value of both investments are classified within other income on the consolidated statements of operations. The Company records interest income at the stated coupon rate of the credit facility and classifies it within interest income on the consolidated statement of operations. Fair value for the equity investment is determined using Level 1 inputs, and fair value of the credit facility investment is determined using Level 3 inputs, such as estimated cash flows and estimated discount rates. The Company recorded a gain of $7.2 million in other income during the year ended September 30, 2024 representing the increase in fair value of these investments. Below are the Company’s non-pension financial assets and liabilities recorded at fair value on a recurring basis within the ASC 820-10 fair value hierarchy: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of September 30, 2024 ​ ​ ​ Quoted Prices in ​ Significant ​ ​ ​ ​ ​ ​ Active Markets for ​ Significant ​ Unobservable ​ ​ ​ ​ ​ ​ Identical Assets ​ Observable ​ Inputs ​ Total ​ ​ Balance Sheet Location ​ (Level 1) ​ Inputs (Level 2) ​ (Level 3) ​ Fair Value ​ ​ (in millions) Interest rate contracts Other current assets ​ $ — ​ $ 9.2 ​ $ — ​ $ 9.2 Interest rate contracts Other non-current assets ​ — ​ 16.5 ​ — ​ 16.5 Interest rate contracts Other current liabilities ​ — ​ (0.9) ​ — ​ (0.9) Interest rate contracts Other long-term liabilities ​ — ​ (3.6) ​ — ​ (3.6) Credit facility investment Other non-current assets ​ — ​ — ​ 21.9 ​ 21.9 Equity investment Other non-current assets ​ 19.4 ​ — ​ — ​ 19.4 Total net assets at fair value ​ ​ ​ $ 19.4 ​ $ 21.2 ​ $ 21.9 ​ $ 62.5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of September 30, 2023 ​ ​ ​ Quoted Prices in ​ Significant ​ ​ ​ ​ ​ ​ Active Markets for ​ Significant ​ Unobservable ​ ​ ​ ​ ​ ​ Identical Assets ​ Observable ​ Inputs ​ ​ Total ​ ​ Balance Sheet Location ​ (Level 1) ​ Inputs (Level 2) ​ (Level 3) ​ Fair Value ​ ​ (in millions) Interest rate contracts ​ Other current assets ​ $ — ​ $ 17.2 ​ $ — ​ $ 17.2 Interest rate contracts ​ Other non-current assets ​ — ​ 37.5 ​ — ​ 37.5 Total net assets at fair value ​ ​ ​ $ — ​ $ 54.7 ​ $ — ​ $ 54.7 ​ The table below sets forth a summary of changes in the fair value of the Company’s Level 3 investment assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year-ended September 30, 2024 ​ ​ Beginning Investment ​ ​ ​ ​ ​ ​ ​ Balance ​ Gains/(Losses) ​ Interest Earned ​ Purchases ​ Sales ​ Ending Balance ​ ​ ​ (in millions) Credit facility investment including accrued interest ​ $ — ​ 0.5 ​ 0.5 ​ 32.5 ​ (11.6) ​ $ 21.9 ​

Concentration of Credit Risk

Concentration of Credit Risk	12 Months Ended
	Sep. 30, 2024
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
	Sep. 30, 2024
Leases
Leases	11. 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 of 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. During the fourth quarter of fiscal 2023, the Company approved a restructuring plan primarily to optimize its office real estate portfolio with its freedom to grow strategy, which initiated a review of the carrying value of right-of-use assets and leasehold improvements. In connection with the review, the Company identified leased assets that were no longer recoverable. The Company recorded an impairment charge of $86.2 million to reduce its right-of-use assets and leasehold improvements to their fair values and recorded the expense in restructuring costs on the Consolidated Statement of Operations. Fair value was determined primarily using Level 3 inputs, such as discounted cash flows. The components of lease expenses are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, 2024 September 30, 2023 September 30, 2022 ​ ​ (in millions) Operating lease cost ​ $ 149.1 ​ $ 164.0 ​ $ 172.5 Finance lease cost: ​ ​ ​ ​ ​ ​ ​ ​ Amortization of right-of-use assets ​ 28.4 ​ ​ 23.1 ​ ​ 18.0 Interest on lease liabilities ​ 2.9 ​ ​ 2.6 ​ ​ 2.2 Variable lease cost ​ 34.6 ​ ​ 34.1 ​ ​ 34.0 Total lease cost ​ $ 215.0 ​ $ 223.8 ​ $ 226.7 ​ Additional balance sheet information related to leases is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in millions except as noted) Balance Sheet Classification September 30, 2024 September 30, 2023 Assets: ​ ​ ​ ​ Operating lease assets Operating lease right-of-use assets ​ $ 432.2 ​ $ 447.0 Finance lease assets Property and equipment – net ​ ​ 62.1 ​ ​ 64.8 Total lease assets ​ $ 494.3 ​ $ 511.8 ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities: ​ ​ ​ ​ ​ ​ Current: ​ ​ ​ ​ ​ ​ Operating lease liabilities Accrued expenses and other current liabilities ​ $ 135.1 ​ $ 139.8 Finance lease liabilities Current portion of long-term debt ​ ​ 25.5 ​ ​ 25.0 Total current lease liabilities ​ ​ 160.6 ​ ​ 164.8 Non-current: ​ ​ ​ ​ ​ ​ Operating lease liabilities Operating lease liabilities, noncurrent ​ ​ 510.6 ​ ​ 548.9 Finance lease liabilities Long-term debt ​ ​ 35.7 ​ ​ 39.8 Total non-current lease liabilities ​ $ 546.3 ​ $ 588.7 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of ​ ​ September 30, 2024 September 30, 2023 September 30, 2022 ​ Weighted average remaining lease term (in years): ​ ​ ​ ​ ​ Operating leases 6.2 ​ 6.4 ​ 6.5 ​ Finance leases 2.6 ​ 2.9 ​ 3.1 ​ Weighted average discount rates: ​ ​ ​ ​ ​ ​ Operating leases 5.1 % 4.3 % 4.0 % Finance leases 4.4 % 4.1 % 3.8 % ​ Additional cash flow information related to leases is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, ​ September 30, ​ September 30, ​ 2024 2023 2022 ​ ​ (in millions) Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ ​ ​ ​ ​ ​ Operating cash flows from operating leases ​ $ 184.9 ​ $ 188.3 ​ $ 201.8 Operating cash flows from finance leases ​ ​ 3.0 ​ ​ 2.5 ​ ​ 2.2 Financing cash flows from finance leases ​ ​ 28.9 ​ ​ 23.7 ​ ​ 19.8 Right-of-use assets obtained in exchange for new operating leases ​ ​ 90.1 ​ ​ 96.6 ​ ​ 90.9 Right-of-use assets obtained in exchange for new finance leases ​ ​ 26.6 ​ ​ 37.5 ​ ​ 26.2 ​ Total remaining lease payments under both the Company’s operating and finance leases are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating Leases Finance Leases Fiscal Year ​ (in millions) 2025 ​ $ 164.4 ​ $ 27.7 2026 ​ 135.2 ​ 21.6 2027 ​ 104.1 ​ 12.9 2028 ​ 90.4 ​ 2.9 2029 ​ ​ 75.0 ​ ​ 0.1 Thereafter ​ 187.1 ​ — Total lease payments ​ $ 756.2 ​ $ 65.2 Less: Amounts representing interest ​ $ (110.5) ​ $ (4.0) Total lease liabilities ​ $ 645.7 ​ $ 61.2 ​

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Sep. 30, 2024
Stockholders' Equity
Stockholders' Equity	12. Stockholders’ Equity Common Stock Units

Share-based Payments

Share-based Payments	12 Months Ended
	Sep. 30, 2024
Share-based Payments
Share-based Payments	13. Share-Based Payments Defined Contribution Plans Stock Incentive Plans 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 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 and directors which are earned based on service conditions. The grant date fair value of PEP awards and restricted stock unit awards is primarily based on that day’s closing market price of the Company’s common stock. Restricted stock unit and PEP unit activity for the year ended September 30 was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ Weighted ​ ​ ​ ​ Average ​ ​ ​ Average ​ ​ Restricted ​ Grant-Date ​ ​ ​ Grant-Date ​ ​ Stock Units ​ Fair Value ​ PEP Units ​ Fair Value ​ (in millions) ​ ​ (in millions) ​ ​ Outstanding at September 30, 2021 ​ 1.3 ​ $ 38.88 ​ 1.2 ​ $ 37.22 Granted 0.3 ​ $ 74.30 ​ 0.2 ​ $ 85.46 PEP units earned (unearned) — ​ $ — ​ 0.6 ​ $ 27.90 Vested (0.5) ​ $ 29.44 ​ (1.3) ​ $ 27.90 Cancelled (0.1) ​ $ 49.74 ​ — ​ $ 56.64 Outstanding at September 30, 2022 1.0 ​ $ 53.05 ​ 0.7 ​ $ 60.60 Granted 0.3 ​ $ 83.64 ​ 0.2 ​ $ 94.64 PEP units earned (unearned) — ​ $ — ​ 0.2 ​ $ 43.19 Vested (0.4) ​ $ 44.35 ​ (0.4) ​ $ 43.19 Cancelled (0.1) ​ $ 62.09 ​ — ​ $ 71.71 Outstanding at September 30, 2023 0.8 ​ $ 68.34 ​ 0.7 ​ $ 75.54 Granted 0.3 ​ $ 92.30 ​ 0.2 ​ $ 104.66 PEP units earned (unearned) — ​ $ — ​ 0.2 ​ $ 52.50 Vested (0.3) ​ $ 50.14 ​ (0.4) ​ $ 52.50 Cancelled — ​ $ 77.32 ​ — ​ $ 89.76 Outstanding at September 30, 2024 0.8 ​ $ 83.96 ​ 0.7 ​ $ 95.38 ​ Total compensation expense related to these share-based payments including stock options was $61.5 million, $45.9 million, and $38.5 million during the years ended September 30, 2024, 2023 and 2022, respectively. Unrecognized compensation expense related to total share-based payments outstanding as of September 30, 2024 and 2023 was $68.7 million and $48.3 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
	Sep. 30, 2024
Income Taxes
Income Taxes	14. Income Taxes Income before income taxes included income from domestic operations of $233.0 million, loss of $129.2 million, and income of $235.2 million for fiscal years ended September 30, 2024, 2023 and 2022 and income from foreign operations of $485.2 million, $342.6 million, and $315.4 million for fiscal years ended September 30, 2024, 2023 and 2022. Income tax expense was comprised of: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ September 30, September 30, September 30, ​ ​ 2024 ​ 2023 ​ 2022 ​ ​ (in millions) Current: ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ $ 15.1 ​ $ 67.7 ​ $ 22.8 State ​ (78.6) ​ ​ 71.9 ​ ​ 16.0 Foreign ​ 63.5 ​ ​ 52.8 ​ ​ 75.8 Total current income tax expense ​ — ​ ​ 192.4 ​ ​ 114.6 Deferred: ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ 45.2 ​ ​ (71.8) ​ ​ 22.1 State ​ 68.1 ​ ​ (84.3) ​ ​ 11.8 Foreign ​ 39.6 ​ ​ 19.8 ​ ​ (12.4) Total deferred income tax expense (benefit) ​ 152.9 ​ ​ (136.3) ​ ​ 21.5 Total income tax expense ​ $ 152.9 ​ $ 56.1 ​ $ 136.1 ​ The major elements contributing to the difference between the U.S. federal statutory rate of 21% for fiscal years ended September 30, 2024, 2023 and 2022 and the effective tax rate are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, ​ September 30, ​ September 30, ​ ​ 2024 ​ 2023 ​ 2022 ​ Amount % Amount % Amount % ​ ​ (in millions) Tax at federal statutory rate ​ $ 150.8 21.0 % $ 44.8 21.0 % $ 115.6 21.0 % State income tax, net of federal benefit ​ (8.5) (1.2) ​ (7.1) (3.3) ​ 20.2 3.7 ​ Foreign residual income ​ ​ 43.8 ​ 6.1 ​ ​ 59.4 ​ 27.8 ​ ​ 46.4 ​ 8.4 ​ Nondeductible costs ​ ​ 20.6 ​ 2.9 ​ ​ 10.7 ​ 5.0 ​ ​ 19.7 ​ 3.6 ​ ACAP investment sale ​ ​ 20.2 ​ 2.8 ​ ​ — ​ — ​ ​ — ​ — ​ Change in uncertain tax positions ​ ​ 18.6 ​ 2.6 ​ ​ 9.4 ​ 4.4 ​ ​ 15.4 ​ 2.8 ​ Tax rate changes ​ ​ 1.2 ​ 0.2 ​ ​ (3.2) ​ (1.5) ​ ​ (4.1) ​ (0.7) ​ Audit settlement ​ ​ 0.5 ​ 0.1 ​ ​ 1.9 ​ 0.9 ​ ​ (1.5) ​ (0.3) ​ Income tax credits and incentives ​ ​ (63.5) ​ (8.8) ​ ​ (68.2) ​ (31.9) ​ ​ (51.0) ​ (9.3) ​ Valuation allowance ​ ​ (12.6) ​ (1.8) ​ ​ 16.6 ​ 7.8 ​ ​ (18.0) ​ (3.3) ​ Exclusion of tax on non-controlling interests ​ ​ (12.5) ​ (1.7) ​ ​ (9.4) ​ (4.4) ​ ​ (5.1) ​ (0.9) ​ Return to provision ​ ​ (3.7) ​ (0.5) ​ ​ (0.5) ​ (0.2) ​ ​ (1.5) ​ (0.3) ​ Foreign tax rate differential ​ ​ (2.8) ​ (0.4) ​ ​ 0.2 ​ 0.1 ​ ​ 1.1 ​ 0.2 ​ Tax exempt income ​ ​ (2.5) ​ (0.4) ​ ​ (3.3) ​ (1.5) ​ ​ (5.9) ​ (1.1) ​ Other items, net ​ ​ 3.3 ​ 0.4 ​ ​ 4.8 ​ 2.1 ​ ​ 4.8 ​ 0.9 ​ Total income tax expense ​ $ 152.9 21.3 % $ 56.1 26.3 % $ 136.1 24.7 % ​ During fiscal 2024, the Company recorded an increase in tax benefit of $38.4 million related to state income taxes due to apportionment factor changes for fiscal years 2016 through 2023. This benefit was partially offset by an increase in tax expense of $23.0 million related to uncertain tax positions. During fiscal 2024, the Company sold certain ACAP investments and recorded a reduction in valuation allowances of $21.0 million and a reduction in deferred tax assets of $20.2 million. In addition, the Company recorded a valuation allowance of $9.3 million related to the remaining ACAP investments. During fiscal 2024, 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 $11.7 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 was no longer needed. During fiscal 2024, the Company settled its tax audit in Hong Kong for fiscal year 2011 through fiscal year 2021 and recorded a tax benefit of $6.9 million due primarily to changes in uncertain tax positions. During fiscal 2023, valuation allowances in the amount of $21.0 million related to the AECOM Capital impairment charge were established for the portion of the charge that is not expected to be realized. During fiscal 2022, valuation allowances in the amount of $21.9 million primarily related to net operating losses in certain foreign entities were released due to sufficient positive evidence. The positive evidence included a realignment of the Company’s global transfer pricing methodology which resulted in forecasting the utilization of the net operating losses within the foreseeable future. The Company is currently under tax audit in several jurisdictions including the U.S. where its federal income tax returns for fiscal 2017 through 2020 are being examined by the IRS. Disputes can arise with tax authorities involving issues related to the timing of deductions, the calculation and use of credits, and the taxation of income in various tax jurisdictions because of differing interpretations or application of tax laws, regulations, and relevant facts. The IRS is currently auditing certain tax credits and the methodology for calculating the credits. While the Company has historically been able to sustain the credits in previous audit cycles without adjustment, the Company believes it’s reasonably possible there could be an adjustment to the liability for uncertain tax positions within the next twelve months related to this matter. However, given the early stages of the audit of these credits, the Company is not able to reasonably estimate the range of potential outcomes. 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, ​ ​ 2024 ​ 2023 ​ ​ (in millions) Deferred tax assets: ​ ​ ​ ​ ​ ​ Compensation and benefit accruals not currently deductible ​ $ 85.4 ​ $ 92.2 Net operating loss carryforwards ​ 107.5 ​ 102.3 Self-insurance reserves ​ 38.3 ​ 23.2 Research and experimentation and other tax credits ​ 67.1 ​ 43.1 Pension liability ​ 34.9 ​ 44.7 Accrued liabilities ​ 265.7 ​ 295.1 Capital loss carryforward ​ ​ 49.5 ​ ​ 64.0 Partnership investment ​ 22.3 ​ 102.0 Other ​ 8.2 ​ 7.1 Total deferred tax assets ​ ​ 678.9 ​ ​ 773.7 Deferred tax liabilities: ​ ​ ​ ​ Unearned revenue ​ (4.1) ​ (7.0) Depreciation and amortization ​ (83.7) ​ (13.1) Acquired intangible assets ​ — ​ (5.4) Investment in subsidiaries ​ ​ (9.9) ​ ​ (10.7) Right of use assets ​ ​ (85.2) ​ ​ (94.0) Contingent consideration ​ (30.5) ​ (34.2) Other ​ (5.4) ​ (15.5) Total deferred tax liabilities ​ ​ (218.8) ​ ​ (179.9) Valuation allowance ​ ​ (160.9) ​ ​ (171.2) Net deferred tax assets ​ $ 299.2 ​ $ 422.6 ​ As of September 30, 2024, and 2023, the Company has available unused federal, foreign and state net operating loss (NOL) carryforwards of $744.6 million and $757.5 million, respectively, which expire at various dates over the next several years and capital loss carryforwards of $181.2 million and $199.4 million, respectively, which mostly expire in 2025; some foreign NOL carryforwards never expire. In addition, as of September 30, 2024, the Company has unused federal, state and foreign research and development credits of $28.4 million, $27.8 million and $4.6 million, respectively, and other credits of $9.7 million which expire at various dates over the next several years. As of September 30, 2024 and 2023, gross deferred tax assets were $678.9 million and $773.7 million, respectively. The Company has recorded a valuation allowance of $160.9 million and $171.2 million as of September 30, 2024 and 2023, 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 $518.0 million will be realized and, as such, no additional valuation allowance has been provided. The net decrease in the valuation allowance of $10.3 million is primarily attributable to a decrease in valuation allowances of $11.7 million related to the ACAP sale in the US, a decrease in valuation allowances on capital losses of $10.4 million, an increase in valuation allowances on foreign net operating losses and currency translation adjustments of $12.3 million, and decreases in valuation allowances of $0.6 million related to state net operating losses and credits. 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 $1.2 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, 2024, and 2023, the Company had a liability for unrecognized tax benefits, including potential interest and penalties, net of related tax benefit, totaling $97.9 million and $79.5 million, respectively. The gross unrecognized tax benefits as of September 30, 2024 and 2023 were $81.3 million and $62.1 million, respectively, excluding interest, penalties, and related tax benefit. Of the $81.3 million, approximately $77.1 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, ​ ​ 2024 ​ 2023 ​ ​ (in millions) Balance at the beginning of the year ​ $ 62.1 ​ $ 55.2 Gross increase in current period’s tax positions ​ 34.5 ​ 3.5 Gross increase in prior years’ tax positions ​ 13.9 ​ 17.9 Gross decrease in prior years’ tax positions ​ (20.1) ​ (13.3) Decrease due to settlement with tax authorities ​ (7.4) ​ (1.0) Decrease due to lapse of statute of limitations ​ (2.2) ​ — Gross change due to foreign exchange fluctuations ​ ​ 0.5 ​ ​ (0.2) Balance at the end of the year ​ $ 81.3 ​ $ 62.1 ​ 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, 2024, the accrued interest and penalties were $27.7 million and $3.5 million, respectively, excluding any related income tax benefits. As of September 30, 2023, the accrued interest and penalties were $24.4 million and $1.5 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
	Sep. 30, 2024
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, ​ 2024 ​ 2023 ​ 2022 ​ ​ (in millions) Denominator for basic earnings per share ​ 135.5 138.6 140.8 Potential common shares ​ 1.0 1.5 1.9 Denominator for diluted earnings per share ​ 136.5 140.1 142.7 ​

Other Financial Information

Other Financial Information	12 Months Ended
	Sep. 30, 2024
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, ​ ​ 2024 ​ 2023 ​ ​ (in millions) Accrued salaries and benefits ​ $ 620.4 ​ $ 599.8 Accrued contract costs ​ 1,354.7 ​ ​ 1,340.4 Other accrued expenses ​ 410.6 ​ ​ 347.3 ​ ​ $ 2,385.7 ​ $ 2,287.5 ​ Accrued contract costs above include balances related to professional liability accruals of $831.8 million and $809.6 million as of September 30, 2024 and 2023, 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, 2024 and 2023. The Company did not have material revisions to estimates for contracts where revenue is recognized using the input method during the twelve months ended September 30, 2024 and 2023. For the year ended September 30, 2024, the Company incurred restructuring expenses of $98.9 million, which included labor - related costs of $18.7 million and non - labor costs of $80.2 million, of which $11.9 million was accrued and unpaid at September 30, 2024. For the year ended September 30, 2023, the Company incurred restructuring expenses of $188.4 million, which included personnel and other costs of $91.6 million and real estate costs of $96.8 million,of which $53.3 million was accrued and unpaid at September 30, 2023. On September 12, 2024, the Company’s Board of Directors declared a quarterly cash dividend of $0.22 per share, which was paid on October 18, 2024 to stockholders of record as of the close of business on October 2, 2024. As of September 30, 2024, accrued and unpaid dividends totaled $31.9 million and were classified within other accrued expenses on the consolidated balance sheet.

Reclassifications out of Accumu

Reclassifications out of Accumulated Other Comprehensive Loss	12 Months Ended
	Sep. 30, 2024
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, 2024, 2023 and 2022 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, 2021 ​ $ (316.2) ​ $ (580.1) ​ $ (4.1) ​ $ (900.4) Other comprehensive income (loss) before reclassification ​ 89.9 ​ ​ (238.7) ​ ​ 37.9 ​ ​ (110.9) Amounts reclassified from accumulated other comprehensive loss ​ 9.0 ​ 19.5 ​ 3.1 ​ 31.6 Balances at September 30, 2022 ​ $ (217.3) ​ $ (799.3) ​ $ 36.9 ​ $ (979.7) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign ​ ​ ​ Accumulated ​ ​ Pension ​ Currency ​ Loss on ​ Other ​ ​ Related ​ Translation ​ Derivative ​ Comprehensive ​ Adjustments Adjustments Instruments Loss Balances at September 30, 2022 ​ $ (217.3) ​ $ (799.3) ​ $ 36.9 ​ $ (979.7) Other comprehensive (loss) income before reclassification ​ ​ (10.9) ​ ​ 59.6 ​ ​ 10.7 ​ ​ 59.4 Amounts reclassified from accumulated other comprehensive loss ​ 2.2 ​ — ​ (8.5) ​ (6.3) Balances at September 30, 2023 ​ $ (226.0) ​ $ (739.7) ​ $ 39.1 ​ $ (926.6) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign ​ ​ ​ Accumulated ​ ​ Pension ​ Currency ​ Loss on ​ Other ​ ​ Related ​ Translation ​ Derivative ​ Comprehensive ​ Adjustments Adjustments Instruments Loss Balances at September 30, 2023 ​ $ (226.0) ​ $ (739.7) ​ $ 39.1 ​ $ (926.6) Other comprehensive (loss) income before reclassification ​ ​ (26.6) ​ ​ 93.2 ​ ​ (10.6) ​ ​ 56.0 Amounts reclassified from accumulated other comprehensive loss ​ 0.6 ​ ​ — ​ ​ (12.7) ​ ​ (12.1) Balances at September 30, 2024 ​ $ (252.0) ​ $ (646.5) ​ $ 15.8 ​ $ (882.7) ​

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Sep. 30, 2024
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. The Company’s unsecured credit arrangements are used for standby letters of credit issued in connection with general and professional liability insurance programs and for contract performance guarantees. At September 30, 2024 and 2023, these outstanding standby letters of credit totaled $934.5 million and $878.9 million, respectively. As of September 30, 2024, the Company had $389.8 million available under these unsecured credit facilities. Performance arrangements typically have various expiration dates ranging from the completion of the project contract and extending beyond contract completion in some 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, 2024, the Company was contingently liable in the amount of approximately $938.9 million in issued standby letters of credit and $5.1 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, 2024, the Company has capital commitments of $5.9 million to the Fund over the next 4 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, limited debt repayment, environmental indemnity obligations and other lender required guarantees. In February 2024, the Company was informed of a potential liability as one of the indemnitors on a divested business’ surety bonds. The Company does not have sufficient information to determine the range of potential impacts, however, it is reasonably possible that the Company may incur additional costs related to these bonds. In connection with the resolution of contingencies related to the sale of the civil infrastructure construction business, the Company agreed to act as an additional guarantor on the counterparty’s existing debt, which matured on September 30, 2024. Department of Energy Deactivation, Demolition, and Removal Project A former affiliate of the Company, Amentum Environment & Energy, Inc., f/k/a AECOM Energy and Construction, Inc. (“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, including the Former Affiliate who worked on the DOE project, to Maverick Purchaser Sub LLC (MS Purchaser), an affiliate of American Securities LLC and Lindsay Goldberg LLC. The Company and the MS Purchaser agreed that all future DOE project claim recoveries and costs will be split 10% to the MS 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 Claims 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. Refinery Turnaround Project The 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. On January 31, 2020, the Company completed the sale of its Management Services business, including the Former Affiliate, to the MS Purchaser; 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
	Sep. 30, 2024
Reportable Segments and Geographic Information
Reportable Segments and Geographic Information	19. Reportable Segments and Geographic Information The Company manages its operations under three reportable segments according to their geographic regions and business activities. In identifying its reportable segments, the Company considered the financial information provided to its chief operating decision maker (CODM), who is the chief executive officer. The financial data is organized by geographic region and global business lines. The CODM uses this information to allocate resources and assess the performance of the segments primarily based on revenue less pass - through revenue and attributable earnings before interest, tax, and amortization expense. After considering various factors, including the development and utilization of financial data to the CODM, the Company concluded that identifying its operating segments by geography was consistent with the objectives of ASC 280-10. Certain operating segments have been aggregated based on similar characteristics, including long-term financial performance, the nature of services provided, internal process for delivering those services, and types of customers, to arrive at the Company’s reportable segments. The Company’s Americas reportable segment provides planning, consulting, architectural and engineering design services, and construction management services to public and private clients in the United States, Canada, and Latin America and is comprised of the Design and Consulting Services Americas and Construction Management operating segments. The Company’s International reportable segment provides similar professional services to public and private clients in Europe and India, the Middle East and Africa, Asia, and Australia and New Zealand and is comprised of the operating segments in those geographic regions. The Company’s AECOM Capital (ACAP) operating segment is its own reportable segment and primarily invests in and develops real estate projects. Certain expenses that are determined to be related to the Company as a whole are not deemed to be part of an operating segment but are reported within Corporate. The following tables set forth summarized financial information concerning the Company’s reportable segments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ AECOM ​ ​ ​ ​ ​ ​ ​ Reportable Segments: Americas International Capital Corporate Total ​ ​ ​ (in millions) Fiscal Year Ended September 30, 2024: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenue ​ $ 12,485.7 ​ $ 3,618.4 ​ $ 1.4 ​ $ — ​ $ 16,105.5 ​ Gross profit ​ 759.1 ​ ​ 323.8 ​ ​ 1.4 ​ ​ — ​ ​ 1,084.3 ​ Equity in earnings of joint ventures ​ 15.5 ​ ​ 13.5 ​ ​ (26.9) ​ ​ — ​ ​ 2.1 ​ General and administrative expenses ​ — ​ ​ — ​ ​ (15.0) ​ ​ (145.1) ​ ​ (160.1) ​ Restructuring costs ​ ​ — ​ ​ — ​ ​ — ​ ​ (98.9) ​ ​ (98.9) ​ Operating income ​ ​ 774.6 ​ ​ 337.3 ​ ​ (40.5) ​ ​ (244.0) ​ ​ 827.4 ​ Segment assets ​ ​ 7,988.1 ​ ​ 2,734.5 ​ ​ 53.2 ​ ​ 1,208.7 ​ ​ ​ ​ Gross profit as a % of revenue ​ 6.1 % ​ 8.9 % ​ — ​ ​ — ​ ​ 6.7 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended September 30, 2023: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenue ​ $ 10,975.7 ​ $ 3,402.1 ​ $ 0.7 ​ $ — ​ $ 14,378.5 ​ Gross profit ​ ​ 699.7 ​ ​ 245.1 ​ ​ 0.7 ​ ​ — ​ ​ 945.5 ​ Equity in earnings of joint ventures ​ ​ 14.9 ​ ​ 9.6 ​ ​ (303.9) ​ ​ — ​ ​ (279.4) ​ General and administrative expenses ​ ​ — ​ ​ — ​ ​ (12.6) ​ ​ (141.0) ​ ​ (153.6) ​ Restructuring costs ​ ​ — ​ ​ — ​ ​ — ​ ​ (188.4) ​ ​ (188.4) ​ Operating income ​ ​ 714.6 ​ ​ 254.7 ​ ​ (315.8) ​ ​ (329.4) ​ ​ 324.1 ​ Segment assets ​ ​ 7,433.1 ​ ​ 2,536.2 ​ ​ 64.5 ​ ​ 1,104.4 ​ ​ ​ ​ Gross profit as a % of revenue ​ ​ 6.4 % ​ 7.2 % ​ — ​ ​ — ​ ​ 6.6 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended September 30, 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenue ​ $ 9,939.3 ​ $ 3,206.7 ​ $ 2.2 ​ $ — ​ $ 13,148.2 ​ Gross profit ​ 639.9 ​ ​ 205.9 ​ ​ 2.2 ​ ​ — ​ ​ 848.0 ​ Equity in earnings of joint ventures ​ 13.9 ​ ​ 15.3 ​ ​ 24.4 ​ ​ — ​ ​ 53.6 ​ General and administrative expenses ​ — ​ ​ — ​ ​ (12.6) ​ ​ (134.7) ​ ​ (147.3) ​ Restructuring costs ​ — ​ ​ — ​ ​ — ​ ​ (107.5) ​ ​ (107.5) ​ Operating income ​ 653.8 ​ ​ 221.2 ​ ​ 14.0 ​ ​ (242.2) ​ ​ 646.8 ​ Segment assets ​ ​ 7,232.2 ​ ​ 2,467.9 ​ ​ 264.9 ​ ​ 1,095.3 ​ ​ ​ ​ Gross profit as a % of revenue ​ 6.4 % 6.4 % ​ — ​ ​ — ​ ​ 6.4 % ​ Geographic Information: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, September 30, September 30, Long-Lived Assets ​ 2024 2023 2022 ​ ​ ​ (in millions) Americas ​ $ 3,315.3 ​ $ 3,478.5 ​ $ 3,906.7 Europe, Middle East, India, Africa ​ ​ 872.9 ​ ​ 803.5 ​ ​ 763.6 Asia-Australia-Pacific ​ 370.7 ​ 342.3 ​ 362.1 Total ​ $ 4,558.9 ​ $ 4,624.3 ​ $ 5,032.4 ​ Long-lived assets consist of noncurrent assets excluding deferred tax assets.

Major Clients

Major Clients	12 Months Ended
	Sep. 30, 2024
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

Schedule II_ Valuation and Qual

Schedule II: Valuation and Qualifying Accounts	12 Months Ended
	Sep. 30, 2024
Schedule II: Valuation and Qualifying Accounts
Schedule II: Valuation and Qualifying Accounts	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 2024 ​ $ 94.2 ​ $ 30.9 ​ $ (38.7) ​ $ 1.5 ​ $ 87.9 Fiscal Year 2023 ​ $ 104.0 ​ $ 40.9 ​ $ (50.8) ​ $ 0.1 ​ $ 94.2 Fiscal Year 2022 ​ $ 92.8 ​ $ 43.9 ​ $ (29.6) ​ $ (3.1) ​ $ 104.0 (a) Primarily relates to accounts written-off and recoveries

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Pay vs Performance Disclosure
Net Income (Loss)	$ 402,266	$ 55,332	$ 310,611

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Sep. 30, 2024 shares
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	ITEM 9B. OTHER INFORMATION During the quarterly period ended September 30, 2024, no director or officer of the Company adopted or terminated a Rule 10b5-1 trading arrangement or a non-Rule 10b5-1 trading arrangement as each term is defined in Item 408(a) of Regulation S-K, except as follows: Name and Title Date of Adoption of Rule 10b5-1 Trading Plan Scheduled Expiration Date of Rule 10b5-1 Trading Plan Aggregate Number of Securities to Be Purchased or Sold David Gan, ​ 8/20/2024 ​ 12/17/2025 ​ Sale of (i) 11,500 shares of common stock, (ii) the number of shares of common stock resulting from the vesting of 6,426 restricted stock awards and accrued dividend equivalents and (iii) the number of shares of common stock resulting from the vesting of Performance Earning Program awards (9,639 shares of common stock at target performance) and accrued dividend equivalents ​
David Gan
Trading Arrangements, by Individual
Name	David Gan
Title	Chief Legal Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	8/20/2024
Expiration Date	12/17/2025
Trading arrangement, of common stock | David Gan
Trading Arrangements, by Individual
Aggregate Available	11,500
Trading arrangement, Vesting of restricted stock awards | David Gan
Trading Arrangements, by Individual
Aggregate Available	6,426
Trading arrangement, common stock at target performance | David Gan
Trading Arrangements, by Individual
Aggregate Available	9,639

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
	Sep. 30, 2024
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. Goodwill is evaluated for impairment either by assessing qualitative factors or by performing a quantitative assessment. Qualitative factors, such as overall financial performance, industry or market considerations, or other relevant events, are assessed to determine if it is more likely than not that the fair value of the reporting units is less than their carrying amounts. During a quantitative 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 On December 22, 2017, the United States enacted the Tax Cuts and Jobs Act, which significantly changed U.S. tax law and included a provision to tax global intangible low-taxed income (GILTI) of foreign subsidiaries. The Company recognizes taxes due under the GILTI provision as a current period expense.

Discontinued Operations, Good_2

Discontinued Operations, Goodwill, and Intangible Assets (Tables)	12 Months Ended
	Sep. 30, 2024
Discontinued Operations, Goodwill, and Intangible Assets
Schedule of balance sheet and income statement information of discontinued operations and significant components included in consolidated statement of cash flows	The following table represents summarized balance sheet information of assets and liabilities held for sale (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ September 30, ​ 2024 2023 ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ $ 4.0 ​ $ 1.9 Receivables and contract assets ​ 73.2 ​ ​ 93.3 Current assets held for sale ​ $ 77.2 ​ $ 95.2 ​ ​ ​ ​ ​ ​ ​ Property and equipment, net ​ $ 16.7 ​ $ 14.2 Other ​ 1.2 ​ ​ — Write-down of assets to fair value less cost to sell ​ ​ (17.9) ​ ​ (14.2) Non-current assets held for sale ​ $ — ​ $ — ​ ​ ​ ​ ​ ​ ​ Accounts payable and accrued expenses ​ $ 35.6 ​ $ 45.6 Current liabilities held for sale ​ $ 35.6 ​ $ 45.6 ​ ​ ​ ​ ​ ​ ​ Long-term liabilities held for sale ​ $ — ​ $ 0.8 ​ The following table represents summarized income statement information of discontinued operations (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, ​ September 30, September 30, ​ 2024 2023 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenue ​ $ 178.2 ​ $ 212.8 ​ $ 347.4 Cost of revenue ​ ​ 181.1 ​ ​ 223.2 ​ ​ 360.2 Gross loss ​ ​ (2.9) ​ ​ (10.4) ​ ​ (12.8) Equity in earnings of joint ventures ​ ​ (3.4) ​ ​ (2.9) ​ ​ (7.4) Loss on disposal activities ​ ​ (97.1) ​ ​ (50.6) ​ ​ (48.1) Transaction costs ​ ​ (0.2) ​ ​ (0.2) ​ ​ (9.7) Loss from operations ​ ​ (103.6) ​ ​ (64.1) ​ ​ (78.0) Other loss ​ ​ (1.5) ​ ​ (1.0) ​ ​ — Interest expense ​ ​ — ​ ​ — ​ ​ (0.1) Loss before taxes ​ ​ (105.1) ​ ​ (65.1) ​ ​ (78.1) Income tax (benefit) expense ​ ​ (0.1) ​ ​ (7.9) ​ ​ 1.8 Net loss from discontinued operations ​ $ (105.0) ​ $ (57.2) ​ $ (79.9) ​ 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, September 30, ​ 2024 2023 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Payments for capital expenditures ​ $ (2.5) ​ $ (6.2) ​ $ (2.7)
Schedule of changes in the carrying value of goodwill by reportable segment	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ Exchange ​ ​ ​ ​ September 30, ​ 2023 Impact Acquired 2024 ​ ​ (in millions) Americas ​ $ 2,614.0 ​ $ 0.6 ​ $ 11.1 ​ $ 2,625.7 International ​ 804.9 ​ ​ 49.6 ​ ​ — ​ ​ 854.5 Total ​ $ 3,418.9 ​ $ 50.2 ​ $ 11.1 ​ $ 3,480.2 ​
Schedule of gross amounts and accumulated amortization of finite intangible assets included in intangible assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2024 ​ September 30, 2023 ​ ​ ​ ​ Gross ​ Accumulated ​ Intangible ​ Gross ​ Accumulated ​ Intangible ​ Amortization ​ Amount Amortization Assets, Net Amount Amortization Assets, Net Period ​ ​ (in millions) ​ (years) Backlog and Customer relationships ​ $ 671.7 ​ $ (664.8) ​ $ 6.9 ​ $ 663.8 ​ $ (646.0) ​ $ 17.8 ​ 1 - 11 ​
Schedule of estimated future amortization expense of intangible assets	​ ​ ​ ​ ​ Fiscal Year (in millions) 2025 ​ $ 2.1 2026 ​ ​ 1.5 2027 ​ 1.5 2028 ​ 1.5 2029 ​ ​ 0.3 Total ​ $ 6.9 ​

Revenue Recognition (Tables)

Revenue Recognition (Tables)	12 Months Ended
	Sep. 30, 2024
Revenue Recognition
Schedule of revenues disaggregated by revenue sources	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, ​ September 30, ​ September 30, ​ 2024 2023 2022 ​ (in millions) Cost reimbursable ​ $ 6,361.4 ​ $ 6,128.8 ​ $ 5,454.9 Guaranteed maximum price ​ ​ 6,030.0 ​ 4,887.7 ​ 4,325.0 Fixed price ​ ​ 3,714.1 ​ 3,362.0 ​ 3,368.3 Total revenue ​ $ 16,105.5 ​ $ 14,378.5 ​ $ 13,148.2 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, ​ September 30, ​ September 30, ​ 2024 2023 2022 ​ (in millions) Americas ​ $ 12,487.0 ​ $ 10,976.4 ​ $ 9,941.6 Europe, Middle East, India, Africa ​ ​ 2,141.5 ​ 1,937.3 ​ 1,759.8 Asia-Australia-Pacific ​ ​ 1,477.0 ​ 1,464.8 ​ 1,446.8 Total revenue ​ $ 16,105.5 ​ $ 14,378.5 ​ $ 13,148.2 ​
Schedule of net accounts receivable	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ September 30, ​ September 30, ​ ​ 2024 2023 ​ ​ (in millions) Billed ​ $ 2,184.9 ​ $ 2,122.2 Contract retentions ​ 696.3 ​ ​ 516.5 Total accounts receivable—gross ​ 2,881.2 ​ ​ 2,638.7 Allowance for doubtful accounts and credit losses ​ (87.9) ​ ​ (94.2) Total accounts receivable—net ​ $ 2,793.3 ​ $ 2,544.5 ​

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Sep. 30, 2024
Property and Equipment
Schedule of property and equipment, at cost	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ ​ ​ ​ ​ September 30, ​ September 30, ​ Useful Lives ​ 2024 2023 (years) ​ ​ (in millions) ​ ​ ​ ​ Building and land ​ $ 10.1 ​ $ 10.4 10 - 45 Leasehold improvements ​ 299.3 ​ 329.4 1 - 20 Computer systems and equipment ​ 659.6 ​ 716.7 3 - 12 Furniture and fixtures ​ 92.2 ​ 97.9 3 - 10 Total ​ 1,061.2 ​ 1,154.4 ​ ​ ​ ​ Accumulated depreciation and amortization ​ (706.8) ​ (771.8) ​ ​ ​ ​ Property and equipment, net ​ $ 354.4 ​ $ 382.6 ​ ​ ​ ​

Joint Ventures and Variable I_2

Joint Ventures and Variable Interest Entities (Tables)	12 Months Ended
	Sep. 30, 2024
Joint Ventures and Variable Interest Entities
Schedule of financial information of the consolidated joint ventures	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ September 30, ​ 2024 2023 ​ ​ (in millions) Current assets ​ $ 836.9 ​ $ 806.3 Non-current assets ​ 83.1 ​ 75.9 Total assets ​ $ 920.0 ​ $ 882.2 ​ ​ ​ ​ ​ ​ ​ Current liabilities ​ $ 763.6 ​ $ 779.6 Non-current liabilities ​ 1.5 ​ 1.5 Total liabilities ​ 765.1 ​ 781.1 Total AECOM deficit ​ (17.2) ​ (54.9) Noncontrolling interests ​ 172.1 ​ 156.0 Total owners’ equity ​ 154.9 ​ 101.1 Total liabilities and owners’ equity ​ $ 920.0 ​ $ 882.2
Schedule of financial information of the unconsolidated joint ventures, as derived from their unaudited financial statements	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ September 30, ​ 2024 2023 ​ ​ (in millions) Current assets ​ $ 1,379.0 ​ $ 1,177.4 Non-current assets ​ 799.9 ​ 996.3 Total assets ​ $ 2,178.9 ​ $ 2,173.7 ​ ​ ​ ​ ​ ​ ​ Current liabilities ​ $ 976.3 ​ $ 605.9 Non-current liabilities ​ 114.8 ​ 441.7 Total liabilities ​ 1,091.1 ​ 1,047.6 Joint ventures’ equity ​ 1,087.8 ​ 1,126.1 Total liabilities and joint ventures’ equity ​ $ 2,178.9 ​ $ 2,173.7 ​ ​ ​ ​ ​ ​ ​ AECOM’s investment in joint ventures ​ $ 138.1 ​ $ 139.2 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Twelve Months Ended ​ ​ September 30, ​ September 30, ​ 2024 2023 ​ ​ (in millions) Revenue ​ $ 2,145.8 ​ $ 1,248.2 Cost of revenue ​ 1,972.1 ​ 1,170.7 Gross profit ​ $ 173.7 ​ $ 77.5 Net income ​ $ 168.6 ​ $ 72.9 ​
Schedule of AECOM's equity in earnings of unconsolidated joint ventures	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ ​ September 30, ​ September 30, ​ September 30, ​ ​ 2024 2023 2022 ​ ​ (in millions) ​ Pass-through joint ventures ​ $ 29.0 ​ $ 24.5 ​ $ 29.2 ​ Other joint ventures ​ (26.9) ​ (303.9) ​ 24.4 ​ Total ​ $ 2.1 ​ $ (279.4) ​ $ 53.6 ​

Pension Benefit Obligations (Ta

Pension Benefit Obligations (Tables)	12 Months Ended
	Sep. 30, 2024
Pension Benefit Obligations
Schedule of reconciliations of the changes in the U.S. and international plans' benefit obligations	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, ​ September 30, ​ September 30, ​ ​ 2024 ​ 2023 ​ 2022 ​ U.S. Int’l U.S. Int’l U.S. Int’l ​ ​ (in millions) Change in benefit obligation: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Benefit obligation at beginning of year ​ $ 181.2 ​ $ 756.2 ​ $ 198.1 ​ $ 791.2 ​ $ 265.4 ​ $ 1,470.8 Service cost ​ — ​ 0.2 ​ — ​ 0.3 ​ — ​ 0.5 Participant contributions ​ 0.1 ​ 0.3 ​ 0.1 ​ 0.2 ​ 0.1 ​ 0.3 Interest cost ​ 9.7 ​ 43.7 ​ 9.8 ​ 47.7 ​ 4.7 ​ 24.1 Benefits and expenses paid ​ (17.6) ​ (47.7) ​ (17.2) ​ (42.2) ​ (18.4) ​ (44.3) Actuarial loss (gain) ​ 13.5 ​ 37.0 ​ (8.8) ​ (112.5) ​ (51.9) ​ (458.1) Plan settlements ​ — ​ (3.2) ​ (1.5) ​ (1.5) ​ (1.8) ​ (2.2) Transfers in ​ ​ — ​ ​ — ​ ​ 0.7 ​ ​ — ​ ​ — ​ ​ — Foreign currency translation (gain) loss ​ — ​ 73.9 ​ — ​ 73.0 ​ — ​ (199.9) Benefit obligation at end of year ​ $ 186.9 ​ $ 860.4 ​ $ 181.2 ​ $ 756.2 ​ $ 198.1 ​ $ 791.2
Schedule of reconciliations of the changes in the fair value of assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, ​ September 30, ​ September 30, ​ ​ 2024 ​ 2023 ​ 2022 ​ 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 ​ $ 98.8 ​ $ 673.3 ​ $ 101.4 ​ $ 683.5 ​ $ 138.9 ​ $ 1,251.8 Actual return on plan assets ​ 15.8 ​ ​ 89.0 ​ 7.8 ​ (54.2) ​ (27.2) ​ (374.5) Employer contributions ​ 11.9 ​ ​ 25.1 ​ 8.2 ​ 24.8 ​ 9.8 ​ 23.6 Participant contributions ​ 0.1 ​ ​ 0.3 ​ 0.1 ​ 0.2 ​ 0.1 ​ 0.3 Benefits and expenses paid ​ (17.6) ​ ​ (47.7) ​ (17.2) ​ (42.2) ​ (18.4) ​ (44.3) Plan settlements ​ — ​ ​ (3.2) ​ (1.5) ​ (1.5) ​ (1.8) ​ (2.2) Foreign currency translation (loss) gain ​ — ​ ​ 67.5 ​ — ​ 62.7 ​ — ​ (171.2) Fair value of plan assets at end of year ​ $ 109.0 ​ $ 804.3 ​ $ 98.8 ​ $ 673.3 ​ $ 101.4 ​ $ 683.5
Schedule of reconciliations of the funded status	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, 2024 ​ September 30, 2023 ​ September 30, 2022 ​ U.S. Int’l U.S. Int’l U.S. Int’l ​ ​ (in millions) Reconciliation of funded status: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Funded status at end of year ​ $ (77.9) ​ $ (56.1) ​ $ (82.4) ​ $ (82.9) ​ $ (96.7) ​ $ (107.7) Contribution made after measurement date ​ N/A ​ ​ N/A ​ N/A ​ N/A ​ N/A ​ N/A Net amount recognized at end of year ​ $ (77.9) ​ $ (56.1) ​ $ (82.4) ​ $ (82.9) ​ $ (96.7) ​ $ (107.7)
Schedule of amounts recognized in the consolidated balance sheets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, 2024 ​ September 30, 2023 ​ September 30, 2022 ​ 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 ​ $ — ​ $ 46.6 ​ $ — ​ $ 38.7 ​ $ — ​ $ 36.8 Accrued expenses and other current liabilities ​ (8.3) ​ ​ — ​ (8.4) ​ — ​ (8.6) ​ — Pension benefit obligations ​ (69.6) ​ ​ (102.7) ​ (74.0) ​ (121.6) ​ (88.1) ​ (144.5) Net amount recognized in the balance sheet ​ $ (77.9) ​ $ (56.1) ​ $ (82.4) ​ $ (82.9) ​ $ (96.7) ​ $ (107.7) ​
Schedule of reconciliation of amounts in the consolidated statements of stockholder's equity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, 2024 ​ September 30, 2023 ​ September 30, 2022 ​ 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 ​ $ (0.1) ​ $ (1.3) ​ $ (0.1) ​ $ (1.2) ​ $ (0.1) ​ $ (1.2) Net loss ​ (77.6) ​ ​ (234.9) ​ ​ (77.5) ​ ​ (207.1) ​ ​ (91.7) ​ ​ (187.1) Total recognized in accumulated other comprehensive loss ​ $ (77.7) ​ $ (236.2) ​ $ (77.6) ​ $ (208.3) ​ $ (91.8) ​ $ (188.3) ​
Schedule of components of net periodic cost for the Company's pension and post-retirement plans	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, 2024 ​ September 30, 2023 ​ September 30, 2022 ​ U.S. Int’l U.S. Int’l U.S. Int’l ​ ​ (in millions) Components of net periodic benefit cost: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Service costs ​ $ — ​ $ 0.2 ​ $ — ​ $ 0.3 ​ $ — ​ $ 0.5 Interest cost on projected benefit obligation ​ 9.7 ​ ​ 43.7 ​ ​ 9.8 ​ ​ 47.7 ​ ​ 4.7 ​ ​ 24.1 Expected return on plan assets ​ (5.5) ​ ​ (57.4) ​ ​ (5.8) ​ ​ (60.8) ​ ​ (5.6) ​ ​ (41.4) Amortization of prior service costs ​ ​ — ​ ​ 0.1 ​ ​ — ​ ​ 0.1 ​ ​ — ​ ​ 0.1 Amortization of net loss (gain) ​ ​ 3.1 ​ ​ (2.3) ​ ​ 3.5 ​ ​ (0.6) ​ ​ 5.6 ​ ​ 6.9 Settlement loss (gain) recognized ​ ​ — ​ ​ 0.1 ​ ​ (0.1) ​ ​ 0.2 ​ ​ 0.2 ​ ​ 0.3 Net periodic benefit cost (credit) ​ $ 7.3 ​ $ (15.6) ​ $ 7.4 ​ $ (13.1) ​ $ 4.9 ​ $ (9.5) ​
Schedule of 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	Amounts included in accumulated other comprehensive loss as of September 30, 2024 that are expected to be recognized as components of net periodic benefit cost during fiscal 2025 are (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Int’l Amortization of prior service cost ​ $ — ​ $ (0.1) Amortization of net actuarial (losses) gain ​ (3.8) ​ 1.3 Total ​ $ (3.8) ​ $ 1.2 ​
Schedule of 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, ​ ​ 2024 ​ 2023 ​ 2022 ​ U.S. Int’l U.S. Int’l U.S. Int’l ​ ​ (in millions) Projected benefit obligation ​ $ 175.1 ​ $ 649.8 ​ $ 168.8 ​ $ 628.1 ​ $ 184.8 ​ $ 601.4 Accumulated benefit obligation ​ $ 175.1 ​ $ 649.8 ​ $ 168.8 ​ $ 628.1 ​ $ 184.8 ​ $ 600.1 Fair value of plan assets ​ $ 109.0 ​ $ 547.1 ​ $ 98.8 ​ $ 506.5 ​ $ 101.4 ​ $ 456.9 ​
Schedule of expected future benefit payments	The table below provides the expected future benefit payments, in millions: ​ ​ ​ ​ ​ ​ ​ ​ Year Ending September 30, U.S. Int’l 2025 ​ $ 20.2 ​ $ 54.6 2026 ​ 19.5 ​ ​ 53.9 2027 ​ 18.3 ​ ​ 55.5 2028 ​ 17.7 ​ ​ 57.2 2029 ​ ​ 16.7 ​ ​ 59.2 2030-2034 ​ 71.2 ​ ​ 317.5 Total ​ $ 163.6 ​ $ 597.9 ​
Schedule of underlying assumptions for the pension plans	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, ​ September 30, ​ September 30, ​ ​ 2024 ​ 2023 ​ 2022 ​ U.S. Int’l U.S. Int’l U.S. Int’l ​ ​ (in millions) ​ Weighted-average assumptions to determine benefit obligation: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Discount rate 4.73 % 5.04 % 5.76 % 5.65 % 5.40 % 5.27 % Salary increase rate N/A ​ 2.91 % N/A ​ 3.06 % N/A ​ 3.48 % Weighted-average assumptions to determine net periodic benefit cost: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Discount rate 5.76 % 5.65 % 5.40 % 5.27 % 2.46 % 1.98 % Salary increase rate N/A ​ 3.06 % N/A ​ 3.48 % N/A ​ 3.13 % Expected long-term rate of return on plan assets 6.90 % 5.74 % 7.00 % 6.04 % 6.25 % 3.93 % ​
Schedule 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 ​ 2024 ​ 2023 ​ U.S. Int’l U.S. Int’l U.S. Int’l Asset Category: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Equities 23 % 22 % 24 % 25 % 33 % 24 % Debt 70 ​ 65 ​ 67 ​ 64 ​ 56 ​ 62 ​ Cash 3 ​ 4 ​ 4 ​ 2 ​ 2 ​ 4 ​ Diversified and other 4 ​ 9 ​ 5 ​ 9 ​ 9 ​ 10 ​ Total 100 % 100 % 100 % 100 % 100 % 100 % ​
Schedule of fair values of the Company's post retirement benefit plan assets by major asset categories	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement as of ​ ​ ​ ​ ​ ​ ​ September 30, 2024 ​ ​ ​ ​ ​ Total ​ Quoted ​ Significant ​ ​ ​ ​ ​ ​ ​ Carrying ​ Prices in ​ Other ​ Significant ​ ​ ​ ​ ​ Value as of ​ Active ​ Observable ​ Unobservable ​ Investments ​ ​ September 30, ​ Markets ​ Inputs ​ Inputs ​ measured at ​ 2024 (Level 1) (Level 2) (Level 3) NAV ​ ​ (in millions) Cash and cash equivalents ​ $ 22.1 ​ $ 22.1 ​ $ — ​ $ — ​ $ — Debt securities ​ ​ 391.5 ​ ​ 391.5 ​ ​ — ​ ​ — ​ ​ — Investment funds: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diversified and equity funds ​ 286.7 ​ ​ 48.5 ​ ​ 13.5 ​ ​ — ​ ​ 224.7 Fixed income funds ​ 213.9 ​ ​ 17.3 ​ ​ 4.1 ​ ​ — ​ ​ 192.5 Absolute return fund ​ ​ 5.9 ​ ​ — ​ ​ — ​ ​ — ​ ​ 5.9 Derivative instruments and other ​ ​ (6.8) ​ ​ 8.2 ​ ​ (15.0) ​ ​ — ​ ​ — Total ​ $ 913.3 ​ $ 487.6 ​ $ 2.6 ​ $ — ​ $ 423.1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement as of ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2023 ​ ​ ​ ​ ​ Total ​ Quoted ​ Significant ​ ​ ​ ​ ​ ​ ​ Carrying ​ Prices in ​ Other ​ Significant ​ ​ ​ ​ ​ Value as of ​ Active ​ Observable ​ Unobservable ​ Investments ​ ​ September 30, ​ Markets ​ Inputs ​ Inputs ​ measured at ​ 2023 (Level 1) (Level 2) (Level 3) NAV ​ ​ (in millions) Cash and cash equivalents ​ $ 29.5 ​ $ 20.2 ​ $ 9.3 ​ $ — ​ $ — Debt securities ​ ​ 338.3 ​ ​ 338.3 ​ ​ — ​ ​ — ​ ​ — Investment funds: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diversified and equity funds ​ 258.4 ​ ​ 30.3 ​ ​ 13.2 ​ ​ — ​ ​ 214.9 Fixed income funds ​ 174.3 ​ ​ 21.7 ​ ​ 4.4 ​ ​ — ​ ​ 148.2 Absolute return fund ​ ​ 8.9 ​ ​ — ​ ​ — ​ ​ — ​ ​ 8.9 Derivative instruments and other ​ ​ (37.3) ​ ​ 1.5 ​ ​ (38.8) ​ ​ — ​ ​ — Total ​ $ 772.1 ​ $ 412.0 ​ $ (11.9) ​ $ — ​ $ 372.0

Debt (Tables)

Debt (Tables)	12 Months Ended
	Sep. 30, 2024
Debt
Schedule of debt	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ September 30, ​ 2024 2023 ​ ​ (in millions) Credit Agreement ​ $ 1,446.6 ​ $ 1,119.8 2027 Senior Notes ​ ​ 997.3 ​ ​ 997.3 Other debt ​ 95.9 ​ ​ 100.2 Total debt ​ 2,539.8 ​ ​ 2,217.3 Less: Current portion of debt and short-term borrowings ​ (66.9) ​ ​ (89.5) Less: Unamortized debt issuance costs ​ ​ (22.6) ​ ​ (14.4) Long-term debt ​ $ 2,450.3 ​ $ 2,113.4 ​
Schedule of maturities of debt	The following table presents, in millions, scheduled maturities of the Company’s debt as of September 30, 2024: ​ ​ ​ ​ ​ Fiscal Year ​ ​ 2025 ​ $ 66.9 2026 ​ 27.1 2027 ​ 1,016.5 2028 ​ 9.6 2029 ​ ​ 756.8 Thereafter ​ 662.9 Total ​ $ 2,539.8

Derivative Financial Instrume_2

Derivative Financial Instruments and Fair Value Measurements (Tables)	12 Months Ended
	Sep. 30, 2024
Derivative Financial Instruments and Fair Value Measurements
Schedule of notional principle, fixed rates and related expiration dates of outstanding interest rate swap agreements	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2024 Notional Amount ​ Notional Amount ​ Fixed ​ Effective ​ Expiration Currency (in millions) Rate Date Date USD ​ ​ 400.0 ​ 1.283 % February 2023 ​ March 2028 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2023 Notional Amount ​ Notional Amount ​ Fixed ​ Effective ​ Expiration Currency (in millions) Rate Date Date USD ​ ​ 400.0 ​ 1.283 % February 2023 ​ March 2028 ​
Schedule of non-pension financial assets and liabilities recorded at fair value on a recurring basis	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of September 30, 2024 ​ ​ ​ Quoted Prices in ​ Significant ​ ​ ​ ​ ​ ​ Active Markets for ​ Significant ​ Unobservable ​ ​ ​ ​ ​ ​ Identical Assets ​ Observable ​ Inputs ​ Total ​ ​ Balance Sheet Location ​ (Level 1) ​ Inputs (Level 2) ​ (Level 3) ​ Fair Value ​ ​ (in millions) Interest rate contracts Other current assets ​ $ — ​ $ 9.2 ​ $ — ​ $ 9.2 Interest rate contracts Other non-current assets ​ — ​ 16.5 ​ — ​ 16.5 Interest rate contracts Other current liabilities ​ — ​ (0.9) ​ — ​ (0.9) Interest rate contracts Other long-term liabilities ​ — ​ (3.6) ​ — ​ (3.6) Credit facility investment Other non-current assets ​ — ​ — ​ 21.9 ​ 21.9 Equity investment Other non-current assets ​ 19.4 ​ — ​ — ​ 19.4 Total net assets at fair value ​ ​ ​ $ 19.4 ​ $ 21.2 ​ $ 21.9 ​ $ 62.5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of September 30, 2023 ​ ​ ​ Quoted Prices in ​ Significant ​ ​ ​ ​ ​ ​ Active Markets for ​ Significant ​ Unobservable ​ ​ ​ ​ ​ ​ Identical Assets ​ Observable ​ Inputs ​ ​ Total ​ ​ Balance Sheet Location ​ (Level 1) ​ Inputs (Level 2) ​ (Level 3) ​ Fair Value ​ ​ (in millions) Interest rate contracts ​ Other current assets ​ $ — ​ $ 17.2 ​ $ — ​ $ 17.2 Interest rate contracts ​ Other non-current assets ​ — ​ 37.5 ​ — ​ 37.5 Total net assets at fair value ​ ​ ​ $ — ​ $ 54.7 ​ $ — ​ $ 54.7
Schedule of changes in the fair value of the Company's Level 3 investment assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year-ended September 30, 2024 ​ ​ Beginning Investment ​ ​ ​ ​ ​ ​ ​ Balance ​ Gains/(Losses) ​ Interest Earned ​ Purchases ​ Sales ​ Ending Balance ​ ​ ​ (in millions) Credit facility investment including accrued interest ​ $ — ​ 0.5 ​ 0.5 ​ 32.5 ​ (11.6) ​ $ 21.9 ​

Leases (Tables)

Leases (Tables)	12 Months Ended
	Sep. 30, 2024
Leases
Schedule of components of lease expenses	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, 2024 September 30, 2023 September 30, 2022 ​ ​ (in millions) Operating lease cost ​ $ 149.1 ​ $ 164.0 ​ $ 172.5 Finance lease cost: ​ ​ ​ ​ ​ ​ ​ ​ Amortization of right-of-use assets ​ 28.4 ​ ​ 23.1 ​ ​ 18.0 Interest on lease liabilities ​ 2.9 ​ ​ 2.6 ​ ​ 2.2 Variable lease cost ​ 34.6 ​ ​ 34.1 ​ ​ 34.0 Total lease cost ​ $ 215.0 ​ $ 223.8 ​ $ 226.7
Schedule of additional balance sheet information related to leases	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in millions except as noted) Balance Sheet Classification September 30, 2024 September 30, 2023 Assets: ​ ​ ​ ​ Operating lease assets Operating lease right-of-use assets ​ $ 432.2 ​ $ 447.0 Finance lease assets Property and equipment – net ​ ​ 62.1 ​ ​ 64.8 Total lease assets ​ $ 494.3 ​ $ 511.8 ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities: ​ ​ ​ ​ ​ ​ Current: ​ ​ ​ ​ ​ ​ Operating lease liabilities Accrued expenses and other current liabilities ​ $ 135.1 ​ $ 139.8 Finance lease liabilities Current portion of long-term debt ​ ​ 25.5 ​ ​ 25.0 Total current lease liabilities ​ ​ 160.6 ​ ​ 164.8 Non-current: ​ ​ ​ ​ ​ ​ Operating lease liabilities Operating lease liabilities, noncurrent ​ ​ 510.6 ​ ​ 548.9 Finance lease liabilities Long-term debt ​ ​ 35.7 ​ ​ 39.8 Total non-current lease liabilities ​ $ 546.3 ​ $ 588.7 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of ​ ​ September 30, 2024 September 30, 2023 September 30, 2022 ​ Weighted average remaining lease term (in years): ​ ​ ​ ​ ​ Operating leases 6.2 ​ 6.4 ​ 6.5 ​ Finance leases 2.6 ​ 2.9 ​ 3.1 ​ Weighted average discount rates: ​ ​ ​ ​ ​ ​ Operating leases 5.1 % 4.3 % 4.0 % Finance leases 4.4 % 4.1 % 3.8 %
Schedule of additional cash flow information related to leases	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, ​ September 30, ​ September 30, ​ 2024 2023 2022 ​ ​ (in millions) Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ ​ ​ ​ ​ ​ Operating cash flows from operating leases ​ $ 184.9 ​ $ 188.3 ​ $ 201.8 Operating cash flows from finance leases ​ ​ 3.0 ​ ​ 2.5 ​ ​ 2.2 Financing cash flows from finance leases ​ ​ 28.9 ​ ​ 23.7 ​ ​ 19.8 Right-of-use assets obtained in exchange for new operating leases ​ ​ 90.1 ​ ​ 96.6 ​ ​ 90.9 Right-of-use assets obtained in exchange for new finance leases ​ ​ 26.6 ​ ​ 37.5 ​ ​ 26.2
Schedule of total remaining lease payments under both the Company's operating and finance leases	​ ​ ​ ​ ​ ​ ​ ​ ​ Operating Leases Finance Leases Fiscal Year ​ (in millions) 2025 ​ $ 164.4 ​ $ 27.7 2026 ​ 135.2 ​ 21.6 2027 ​ 104.1 ​ 12.9 2028 ​ 90.4 ​ 2.9 2029 ​ ​ 75.0 ​ ​ 0.1 Thereafter ​ 187.1 ​ — Total lease payments ​ $ 756.2 ​ $ 65.2 Less: Amounts representing interest ​ $ (110.5) ​ $ (4.0) Total lease liabilities ​ $ 645.7 ​ $ 61.2 ​

Share-based Payments (Tables)

Share-based Payments (Tables)	12 Months Ended
	Sep. 30, 2024
Share-based Payments
Schedule of restricted stock unit and PEP unit activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ Weighted ​ ​ ​ ​ Average ​ ​ ​ Average ​ ​ Restricted ​ Grant-Date ​ ​ ​ Grant-Date ​ ​ Stock Units ​ Fair Value ​ PEP Units ​ Fair Value ​ (in millions) ​ ​ (in millions) ​ ​ Outstanding at September 30, 2021 ​ 1.3 ​ $ 38.88 ​ 1.2 ​ $ 37.22 Granted 0.3 ​ $ 74.30 ​ 0.2 ​ $ 85.46 PEP units earned (unearned) — ​ $ — ​ 0.6 ​ $ 27.90 Vested (0.5) ​ $ 29.44 ​ (1.3) ​ $ 27.90 Cancelled (0.1) ​ $ 49.74 ​ — ​ $ 56.64 Outstanding at September 30, 2022 1.0 ​ $ 53.05 ​ 0.7 ​ $ 60.60 Granted 0.3 ​ $ 83.64 ​ 0.2 ​ $ 94.64 PEP units earned (unearned) — ​ $ — ​ 0.2 ​ $ 43.19 Vested (0.4) ​ $ 44.35 ​ (0.4) ​ $ 43.19 Cancelled (0.1) ​ $ 62.09 ​ — ​ $ 71.71 Outstanding at September 30, 2023 0.8 ​ $ 68.34 ​ 0.7 ​ $ 75.54 Granted 0.3 ​ $ 92.30 ​ 0.2 ​ $ 104.66 PEP units earned (unearned) — ​ $ — ​ 0.2 ​ $ 52.50 Vested (0.3) ​ $ 50.14 ​ (0.4) ​ $ 52.50 Cancelled — ​ $ 77.32 ​ — ​ $ 89.76 Outstanding at September 30, 2024 0.8 ​ $ 83.96 ​ 0.7 ​ $ 95.38

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Sep. 30, 2024
Income Taxes
Schedule of income tax (benefit) expense	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ September 30, September 30, September 30, ​ ​ 2024 ​ 2023 ​ 2022 ​ ​ (in millions) Current: ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ $ 15.1 ​ $ 67.7 ​ $ 22.8 State ​ (78.6) ​ ​ 71.9 ​ ​ 16.0 Foreign ​ 63.5 ​ ​ 52.8 ​ ​ 75.8 Total current income tax expense ​ — ​ ​ 192.4 ​ ​ 114.6 Deferred: ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ 45.2 ​ ​ (71.8) ​ ​ 22.1 State ​ 68.1 ​ ​ (84.3) ​ ​ 11.8 Foreign ​ 39.6 ​ ​ 19.8 ​ ​ (12.4) Total deferred income tax expense (benefit) ​ 152.9 ​ ​ (136.3) ​ ​ 21.5 Total income tax expense ​ $ 152.9 ​ $ 56.1 ​ $ 136.1 ​
Schedule of major elements contributing to the difference between the U.S. federal statutory rate of 21% for fiscal years ended September 30, 2022, 2021 and 2020 and the effective tax rate	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, ​ September 30, ​ September 30, ​ ​ 2024 ​ 2023 ​ 2022 ​ Amount % Amount % Amount % ​ ​ (in millions) Tax at federal statutory rate ​ $ 150.8 21.0 % $ 44.8 21.0 % $ 115.6 21.0 % State income tax, net of federal benefit ​ (8.5) (1.2) ​ (7.1) (3.3) ​ 20.2 3.7 ​ Foreign residual income ​ ​ 43.8 ​ 6.1 ​ ​ 59.4 ​ 27.8 ​ ​ 46.4 ​ 8.4 ​ Nondeductible costs ​ ​ 20.6 ​ 2.9 ​ ​ 10.7 ​ 5.0 ​ ​ 19.7 ​ 3.6 ​ ACAP investment sale ​ ​ 20.2 ​ 2.8 ​ ​ — ​ — ​ ​ — ​ — ​ Change in uncertain tax positions ​ ​ 18.6 ​ 2.6 ​ ​ 9.4 ​ 4.4 ​ ​ 15.4 ​ 2.8 ​ Tax rate changes ​ ​ 1.2 ​ 0.2 ​ ​ (3.2) ​ (1.5) ​ ​ (4.1) ​ (0.7) ​ Audit settlement ​ ​ 0.5 ​ 0.1 ​ ​ 1.9 ​ 0.9 ​ ​ (1.5) ​ (0.3) ​ Income tax credits and incentives ​ ​ (63.5) ​ (8.8) ​ ​ (68.2) ​ (31.9) ​ ​ (51.0) ​ (9.3) ​ Valuation allowance ​ ​ (12.6) ​ (1.8) ​ ​ 16.6 ​ 7.8 ​ ​ (18.0) ​ (3.3) ​ Exclusion of tax on non-controlling interests ​ ​ (12.5) ​ (1.7) ​ ​ (9.4) ​ (4.4) ​ ​ (5.1) ​ (0.9) ​ Return to provision ​ ​ (3.7) ​ (0.5) ​ ​ (0.5) ​ (0.2) ​ ​ (1.5) ​ (0.3) ​ Foreign tax rate differential ​ ​ (2.8) ​ (0.4) ​ ​ 0.2 ​ 0.1 ​ ​ 1.1 ​ 0.2 ​ Tax exempt income ​ ​ (2.5) ​ (0.4) ​ ​ (3.3) ​ (1.5) ​ ​ (5.9) ​ (1.1) ​ Other items, net ​ ​ 3.3 ​ 0.4 ​ ​ 4.8 ​ 2.1 ​ ​ 4.8 ​ 0.9 ​ Total income tax expense ​ $ 152.9 21.3 % $ 56.1 26.3 % $ 136.1 24.7 %
Schedule of deferred tax assets (liabilities)	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ September 30, September 30, ​ ​ 2024 ​ 2023 ​ ​ (in millions) Deferred tax assets: ​ ​ ​ ​ ​ ​ Compensation and benefit accruals not currently deductible ​ $ 85.4 ​ $ 92.2 Net operating loss carryforwards ​ 107.5 ​ 102.3 Self-insurance reserves ​ 38.3 ​ 23.2 Research and experimentation and other tax credits ​ 67.1 ​ 43.1 Pension liability ​ 34.9 ​ 44.7 Accrued liabilities ​ 265.7 ​ 295.1 Capital loss carryforward ​ ​ 49.5 ​ ​ 64.0 Partnership investment ​ 22.3 ​ 102.0 Other ​ 8.2 ​ 7.1 Total deferred tax assets ​ ​ 678.9 ​ ​ 773.7 Deferred tax liabilities: ​ ​ ​ ​ Unearned revenue ​ (4.1) ​ (7.0) Depreciation and amortization ​ (83.7) ​ (13.1) Acquired intangible assets ​ — ​ (5.4) Investment in subsidiaries ​ ​ (9.9) ​ ​ (10.7) Right of use assets ​ ​ (85.2) ​ ​ (94.0) Contingent consideration ​ (30.5) ​ (34.2) Other ​ (5.4) ​ (15.5) Total deferred tax liabilities ​ ​ (218.8) ​ ​ (179.9) Valuation allowance ​ ​ (160.9) ​ ​ (171.2) Net deferred tax assets ​ $ 299.2 ​ $ 422.6 ​
Schedule of reconciliation of the beginning and ending amount of gross unrecognized tax benefits	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ September 30, September 30, ​ ​ 2024 ​ 2023 ​ ​ (in millions) Balance at the beginning of the year ​ $ 62.1 ​ $ 55.2 Gross increase in current period’s tax positions ​ 34.5 ​ 3.5 Gross increase in prior years’ tax positions ​ 13.9 ​ 17.9 Gross decrease in prior years’ tax positions ​ (20.1) ​ (13.3) Decrease due to settlement with tax authorities ​ (7.4) ​ (1.0) Decrease due to lapse of statute of limitations ​ (2.2) ​ — Gross change due to foreign exchange fluctuations ​ ​ 0.5 ​ ​ (0.2) Balance at the end of the year ​ $ 81.3 ​ $ 62.1 ​

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Sep. 30, 2024
Earnings Per Share
Schedule of reconciliation of the denominators for basic and diluted earnings per share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, September 30, September 30, ​ 2024 ​ 2023 ​ 2022 ​ ​ (in millions) Denominator for basic earnings per share ​ 135.5 138.6 140.8 Potential common shares ​ 1.0 1.5 1.9 Denominator for diluted earnings per share ​ 136.5 140.1 142.7 ​

Other Financial Information (Ta

Other Financial Information (Tables)	12 Months Ended
	Sep. 30, 2024
Other Financial Information
Schedule of accrued expenses and other current liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ September 30, September 30, ​ ​ 2024 ​ 2023 ​ ​ (in millions) Accrued salaries and benefits ​ $ 620.4 ​ $ 599.8 Accrued contract costs ​ 1,354.7 ​ ​ 1,340.4 Other accrued expenses ​ 410.6 ​ ​ 347.3 ​ ​ $ 2,385.7 ​ $ 2,287.5 ​

Reclassifications out of Accu_2

Reclassifications out of Accumulated Other Comprehensive Loss (Tables)	12 Months Ended
	Sep. 30, 2024
Reclassifications out of Accumulated Other Comprehensive Loss
Schedule of accumulated balances and reporting period activities related to reclassifications out of accumulated other comprehensive loss	The accumulated balances and reporting period activities for the years ended September 30, 2024, 2023 and 2022 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, 2021 ​ $ (316.2) ​ $ (580.1) ​ $ (4.1) ​ $ (900.4) Other comprehensive income (loss) before reclassification ​ 89.9 ​ ​ (238.7) ​ ​ 37.9 ​ ​ (110.9) Amounts reclassified from accumulated other comprehensive loss ​ 9.0 ​ 19.5 ​ 3.1 ​ 31.6 Balances at September 30, 2022 ​ $ (217.3) ​ $ (799.3) ​ $ 36.9 ​ $ (979.7) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign ​ ​ ​ Accumulated ​ ​ Pension ​ Currency ​ Loss on ​ Other ​ ​ Related ​ Translation ​ Derivative ​ Comprehensive ​ Adjustments Adjustments Instruments Loss Balances at September 30, 2022 ​ $ (217.3) ​ $ (799.3) ​ $ 36.9 ​ $ (979.7) Other comprehensive (loss) income before reclassification ​ ​ (10.9) ​ ​ 59.6 ​ ​ 10.7 ​ ​ 59.4 Amounts reclassified from accumulated other comprehensive loss ​ 2.2 ​ — ​ (8.5) ​ (6.3) Balances at September 30, 2023 ​ $ (226.0) ​ $ (739.7) ​ $ 39.1 ​ $ (926.6) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign ​ ​ ​ Accumulated ​ ​ Pension ​ Currency ​ Loss on ​ Other ​ ​ Related ​ Translation ​ Derivative ​ Comprehensive ​ Adjustments Adjustments Instruments Loss Balances at September 30, 2023 ​ $ (226.0) ​ $ (739.7) ​ $ 39.1 ​ $ (926.6) Other comprehensive (loss) income before reclassification ​ ​ (26.6) ​ ​ 93.2 ​ ​ (10.6) ​ ​ 56.0 Amounts reclassified from accumulated other comprehensive loss ​ 0.6 ​ ​ — ​ ​ (12.7) ​ ​ (12.1) Balances at September 30, 2024 ​ $ (252.0) ​ $ (646.5) ​ $ 15.8 ​ $ (882.7) ​

Reportable Segments and Geogr_2

Reportable Segments and Geographic Information (Tables)	12 Months Ended
	Sep. 30, 2024
Reportable Segments and Geographic Information
Summary of financial information concerning the Company's reportable segments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ AECOM ​ ​ ​ ​ ​ ​ ​ Reportable Segments: Americas International Capital Corporate Total ​ ​ ​ (in millions) Fiscal Year Ended September 30, 2024: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenue ​ $ 12,485.7 ​ $ 3,618.4 ​ $ 1.4 ​ $ — ​ $ 16,105.5 ​ Gross profit ​ 759.1 ​ ​ 323.8 ​ ​ 1.4 ​ ​ — ​ ​ 1,084.3 ​ Equity in earnings of joint ventures ​ 15.5 ​ ​ 13.5 ​ ​ (26.9) ​ ​ — ​ ​ 2.1 ​ General and administrative expenses ​ — ​ ​ — ​ ​ (15.0) ​ ​ (145.1) ​ ​ (160.1) ​ Restructuring costs ​ ​ — ​ ​ — ​ ​ — ​ ​ (98.9) ​ ​ (98.9) ​ Operating income ​ ​ 774.6 ​ ​ 337.3 ​ ​ (40.5) ​ ​ (244.0) ​ ​ 827.4 ​ Segment assets ​ ​ 7,988.1 ​ ​ 2,734.5 ​ ​ 53.2 ​ ​ 1,208.7 ​ ​ ​ ​ Gross profit as a % of revenue ​ 6.1 % ​ 8.9 % ​ — ​ ​ — ​ ​ 6.7 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended September 30, 2023: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenue ​ $ 10,975.7 ​ $ 3,402.1 ​ $ 0.7 ​ $ — ​ $ 14,378.5 ​ Gross profit ​ ​ 699.7 ​ ​ 245.1 ​ ​ 0.7 ​ ​ — ​ ​ 945.5 ​ Equity in earnings of joint ventures ​ ​ 14.9 ​ ​ 9.6 ​ ​ (303.9) ​ ​ — ​ ​ (279.4) ​ General and administrative expenses ​ ​ — ​ ​ — ​ ​ (12.6) ​ ​ (141.0) ​ ​ (153.6) ​ Restructuring costs ​ ​ — ​ ​ — ​ ​ — ​ ​ (188.4) ​ ​ (188.4) ​ Operating income ​ ​ 714.6 ​ ​ 254.7 ​ ​ (315.8) ​ ​ (329.4) ​ ​ 324.1 ​ Segment assets ​ ​ 7,433.1 ​ ​ 2,536.2 ​ ​ 64.5 ​ ​ 1,104.4 ​ ​ ​ ​ Gross profit as a % of revenue ​ ​ 6.4 % ​ 7.2 % ​ — ​ ​ — ​ ​ 6.6 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended September 30, 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenue ​ $ 9,939.3 ​ $ 3,206.7 ​ $ 2.2 ​ $ — ​ $ 13,148.2 ​ Gross profit ​ 639.9 ​ ​ 205.9 ​ ​ 2.2 ​ ​ — ​ ​ 848.0 ​ Equity in earnings of joint ventures ​ 13.9 ​ ​ 15.3 ​ ​ 24.4 ​ ​ — ​ ​ 53.6 ​ General and administrative expenses ​ — ​ ​ — ​ ​ (12.6) ​ ​ (134.7) ​ ​ (147.3) ​ Restructuring costs ​ — ​ ​ — ​ ​ — ​ ​ (107.5) ​ ​ (107.5) ​ Operating income ​ 653.8 ​ ​ 221.2 ​ ​ 14.0 ​ ​ (242.2) ​ ​ 646.8 ​ Segment assets ​ ​ 7,232.2 ​ ​ 2,467.9 ​ ​ 264.9 ​ ​ 1,095.3 ​ ​ ​ ​ Gross profit as a % of revenue ​ 6.4 % 6.4 % ​ — ​ ​ — ​ ​ 6.4 % ​
Schedule of Geographic Information	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fiscal Year Ended ​ ​ September 30, September 30, September 30, Long-Lived Assets ​ 2024 2023 2022 ​ ​ ​ (in millions) Americas ​ $ 3,315.3 ​ $ 3,478.5 ​ $ 3,906.7 Europe, Middle East, India, Africa ​ ​ 872.9 ​ ​ 803.5 ​ ​ 763.6 Asia-Australia-Pacific ​ 370.7 ​ 342.3 ​ 362.1 Total ​ $ 4,558.9 ​ $ 4,624.3 ​ $ 5,032.4 ​

Significant Accounting Polici_3

Significant Accounting Policies - Fiscal Year (Details)	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Significant Accounting Policies
Length of fiscal year	364 days	364 days	364 days
Minimum
Significant Accounting Policies
Length of fiscal year	364 days
Maximum
Significant Accounting Policies
Length of fiscal year	371 days

Significant Accounting Polici_4

Significant Accounting Policies - Property and Equipment (Details)	Sep. 30, 2024
Minimum | Building and land
Property, Plant and Equipment [Line Items]
Estimated useful live (in years)	10 years
Minimum | Furniture and fixtures
Property, Plant and Equipment [Line Items]
Estimated useful live (in years)	3 years
Minimum | Computer systems and equipment
Property, Plant and Equipment [Line Items]
Estimated useful live (in years)	3 years
Maximum | Building and land
Property, Plant and Equipment [Line Items]
Estimated useful live (in years)	45 years
Maximum | Furniture and fixtures
Property, Plant and Equipment [Line Items]
Estimated useful live (in years)	10 years
Maximum | Computer systems and equipment
Property, Plant and Equipment [Line Items]
Estimated useful live (in years)	12 years

Significant Accounting Polici_5

Significant Accounting Policies - Pension Plans (Details)	12 Months Ended
	Sep. 30, 2024
Significant Accounting Policies
Market-related valuation calculation period (in years)	5 years
Net unrecognized gain (loss) threshold subject to amortization (in percent)	10%

Discontinued Operations, Good_3

Discontinued Operations, Goodwill, and Intangible Assets - Sale of businesses (Details) - Disposal by Sale - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Mar. 31, 2023	Sep. 30, 2024
Civil infrastructure construction business
Discontinued Operations, Goodwill and Intangible Assets
Gain(loss) from sale of discontinued business	$ 12.7
Committing fund	$ 30
Cash outflow to fund credit facility				$ 21
Oil and gas construction business
Discontinued Operations, Goodwill and Intangible Assets
Gain(loss) from sale of discontinued business		$ (103.1)	$ (38.9)

Discontinued Operations, Good_4

Discontinued Operations, Goodwill, and Intangible Assets - Balance sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023
Summary of financial information of the Disposal Group is as follows:
Long-term liabilities held for sale		$ 792
Held for sale
Summary of financial information of the Disposal Group is as follows:
Cash and cash equivalents	$ 4,000	1,900
Receivables and contract assets	73,200	93,300
Current assets held for sale	77,200	95,200
Property and equipment, net	16,700	14,200
Other	1,200
Write-down of assets to fair value less cost to sell	(17,900)	(14,200)
Accounts payable and accrued expenses	35,600	45,600
Current liabilities held for sale	$ 35,600	45,600
Long-term liabilities held for sale		$ 800

Discontinued Operations, Good_5

Discontinued Operations, Goodwill, and Intangible Assets - Income statement information (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Discontinued Operations, Goodwill and Intangible Assets
Net loss from discontinued operations	$ (104,997)	$ (57,207)	$ (79,929)
Held for sale
Discontinued Operations, Goodwill and Intangible Assets
Revenue	178,200	212,800	347,400
Cost of revenue	181,100	223,200	360,200
Gross loss	(2,900)	(10,400)	(12,800)
Equity in earnings of joint ventures	(3,400)	(2,900)	(7,400)
Loss on disposal activities	(97,100)	(50,600)	(48,100)
Transaction costs	(200)	(200)	(9,700)
Loss from operations	(103,600)	(64,100)	(78,000)
Other loss	(1,500)	(1,000)
Interest expense			(100)
Loss before taxes	(105,100)	(65,100)	(78,100)
Income tax (benefit) expense	(100)	(7,900)	1,800
Net loss from discontinued operations	$ (105,000)	$ (57,200)	$ (79,900)

Discontinued Operations, Good_6

Discontinued Operations, Goodwill, and Intangible Assets - Statement of cash flows (Details) - Held for sale - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Discontinued Operations, Goodwill and Intangible Assets
Payments for capital expenditures	$ (2.5)	$ (6.2)	$ (2.7)
Non-cash gain in discontinued operations	$ 12.7

Discontinued Operations, Good_7

Discontinued Operations, Goodwill, and Intangible Assets - Goodwill by segments (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2024 USD ($)
Changes in the carrying value of goodwill by reporting segment
Goodwill at the beginning of the period	$ 3,418,930
Foreign exchange impact	50,200
Acquired	11,100
Goodwill at the end of the period	3,480,155
Americas
Changes in the carrying value of goodwill by reporting segment
Goodwill at the beginning of the period	2,614,000
Foreign exchange impact	600
Acquired	11,100
Goodwill at the end of the period	2,625,700
International
Changes in the carrying value of goodwill by reporting segment
Goodwill at the beginning of the period	804,900
Foreign exchange impact	49,600
Goodwill at the end of the period	$ 854,500

Discontinued Operations, Good_8

Discontinued Operations, Goodwill, and Intangible Assets - Intangible assets (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023
Discontinued Operations, Goodwill and Intangible Assets
Intangible Assets, Net	$ 6,932	$ 17,769
Customer relationships
Discontinued Operations, Goodwill and Intangible Assets
Gross Amount	671,700	663,800
Accumulated Amortization	(664,800)	(646,000)
Intangible Assets, Net	$ 6,900	$ 17,800
Customer relationships | Minimum
Discontinued Operations, Goodwill and Intangible Assets
Amortization Period	1 year
Customer relationships | Maximum
Discontinued Operations, Goodwill and Intangible Assets
Amortization Period	11 years

Discontinued Operations, Good_9

Discontinued Operations, Goodwill, and Intangible Assets - Amortization expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Discontinued Operations, Goodwill, and Intangible Assets
Amortization expense	$ 18,800	$ 18,600
Discontinued Operations, Goodwill and Intangible Assets
2025	2,100
2026	1,500
2027	1,500
2028	1,500
2029	300
Intangible Assets, Net	$ 6,932	$ 17,769

Revenue Recognition (Details)

Revenue Recognition (Details) - USD ($) $ in Billions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Revenue Recognition
Passed through costs included in revenue and cost of sales	$ 8.9	$ 7.7	$ 6.8

Revenue Recognition - Disaggreg

Revenue Recognition - Disaggregated revenues (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Revenue Recognition
Total revenue	$ 16,105.5	$ 14,378.5	$ 13,148.2
Americas
Revenue Recognition
Total revenue	12,487	10,976.4	9,941.6
Europe, Middle East, India, Africa
Revenue Recognition
Total revenue	2,141.5	1,937.3	1,759.8
Asia-Australia-Pacific
Revenue Recognition
Total revenue	1,477	1,464.8	1,446.8
Cost reimbursable
Revenue Recognition
Total revenue	6,361.4	6,128.8	5,454.9
Guaranteed maximum price
Revenue Recognition
Total revenue	6,030	4,887.7	4,325
Fixed price
Revenue Recognition
Total revenue	$ 3,714.1	$ 3,362	$ 3,368.3

Revenue Recognition - Performan

Revenue Recognition - Performance obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Revenue Recognition
Performance obligation	$ 19,800
Recognized revenue	$ 801	$ 1,043.7
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-10-01
Revenue Recognition
Performance obligation, percent to be satisfied	60%
Performance obligation expected timing of satisfaction period	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-10-01
Revenue Recognition
Performance obligation expected timing of satisfaction period	2 years

Revenue Recognition - Accounts

Revenue Recognition - Accounts receivable, net (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Billed	$ 2,184,900	$ 2,122,200
Contract retentions	696,300	516,500
Total accounts receivable-gross	2,881,200	2,638,700
Allowance for doubtful accounts and credit losses	(87,900)	(94,200)
Total accounts receivable-net	$ 2,793,307	$ 2,544,453
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	$ 180,000	$ 160,000
Trade receivables sold with no financial and legal obligations	$ 319,500	$ 291,000
Outstanding receivables
Additional disclosures
Number of customers accounting for 10%	No	No
Concentration of risk threshold percentage	10%	10%

Property and Equipment (Details

Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Property and equipment
Property and equipment, gross	$ 1,061,200	$ 1,154,400
Accumulated depreciation and amortization	(706,800)	(771,800)
Property and equipment, net	354,377	382,638
Depreciation expense	152,300	152,300	$ 147,000
Building and land
Property and equipment
Property and equipment, gross	10,100	10,400
Leasehold improvements
Property and equipment
Property and equipment, gross	299,300	329,400
Computer systems and equipment
Property and equipment
Property and equipment, gross	659,600	716,700
Furniture and fixtures
Property and equipment
Property and equipment, gross	$ 92,200	$ 97,900

Property and Equipment - Useful

Property and Equipment - Useful Lives (Details)	Sep. 30, 2024
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	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Joint Ventures and Variable Interest Entities
Current assets	$ 7,176,059	$ 6,169,511
TOTAL ASSETS	12,061,669	11,233,398
Current liabilities	6,374,081	5,850,283
TOTAL LIABILITIES	9,691,259	8,849,687
Total AECOM deficit	2,184,205	2,212,332
Noncontrolling interests	186,205	171,379
TOTAL STOCKHOLDERS' EQUITY	2,370,410	2,383,711	$ 2,605,379	$ 2,829,577
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	12,061,669	11,233,398
Revenue	16,105,498	14,378,461	13,148,182
Consolidated joint ventures
Joint Ventures and Variable Interest Entities
Current assets	836,900	806,300
Non-current assets	83,100	75,900
TOTAL ASSETS	920,000	882,200
Current liabilities	763,600	779,600
Non-current liabilities	1,500	1,500
TOTAL LIABILITIES	765,100	781,100
Total AECOM deficit	(17,200)	(54,900)
Noncontrolling interests	172,100	156,000
TOTAL STOCKHOLDERS' EQUITY	154,900	101,100
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	920,000	882,200
Revenue	$ 2,242,800	$ 1,984,300	$ 1,411,700

Joint Ventures and Variable I_4

Joint Ventures and Variable Interest Entities - Unconsolidated (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Financial Information
Current assets	$ 7,176,059	$ 6,169,511
TOTAL ASSETS	12,061,669	11,233,398
Current liabilities	6,374,081	5,850,283
TOTAL LIABILITIES	9,691,259	8,849,687
Joint ventures' equity	2,370,410	2,383,711	$ 2,605,379	$ 2,829,577
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	12,061,669	11,233,398
AECOM's investment in joint ventures	138,067	139,236
Joint ventures summarized financial information
Revenue	16,105,498	14,378,461	13,148,182
Cost of revenue	15,021,157	13,432,996	12,300,208
Gross profit	1,084,341	945,465	847,974
Net income	460,255	100,141	$ 334,702
Unconsolidated joint ventures
Financial Information
Current assets	1,379,000	1,177,400
Non-current assets	799,900	996,300
TOTAL ASSETS	2,178,900	2,173,700
Current liabilities	976,300	605,900
Non-current liabilities	114,800	441,700
TOTAL LIABILITIES	1,091,100	1,047,600
Joint ventures' equity	1,087,800	1,126,100
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	2,178,900	2,173,700
AECOM's investment in joint ventures	138,100	139,200
Joint ventures summarized financial information
Revenue	2,145,800	1,248,200
Cost of revenue	1,972,100	1,170,700
Gross profit	173,700	77,500
Net income	$ 168,600	$ 72,900

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
	Dec. 31, 2023	Jun. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Financial Information
Equity in (losses) earnings of joint ventures			$ 2,124	$ (279,352)	$ 53,640
Impairment loss	$ 35,900	$ 307,000
Unconsolidated joint ventures
Financial Information
Equity in (losses) earnings of joint ventures			2,100	(279,400)	53,600
Unconsolidated joint ventures | Pass-through joint ventures
Financial Information
Equity in (losses) earnings of joint ventures			29,000	24,500	29,200
Unconsolidated joint ventures | Other joint ventures
Financial Information
Equity in (losses) earnings of joint ventures			$ (26,900)	$ (303,900)	$ 24,400

Pension Benefit Obligations - B

Pension Benefit Obligations - Benefit Obligation (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
United States
Change in benefit obligation:
Benefit obligation at beginning of year	$ 181.2	$ 198.1	$ 265.4
Participant contributions	0.1	0.1	0.1
Interest cost	9.7	9.8	4.7
Benefits and expenses paid	(17.6)	(17.2)	(18.4)
Actuarial loss (gain)	13.5	(8.8)	(51.9)
Plan settlements		(1.5)	(1.8)
Transfers in		0.7
Benefit obligation at end of year	186.9	181.2	198.1
International
Change in benefit obligation:
Benefit obligation at beginning of year	756.2	791.2	1,470.8
Service cost	0.2	0.3	0.5
Participant contributions	0.3	0.2	0.3
Interest cost	43.7	47.7	24.1
Benefits and expenses paid	(47.7)	(42.2)	(44.3)
Actuarial loss (gain)	37	(112.5)	(458.1)
Plan settlements	(3.2)	(1.5)	(2.2)
Foreign currency translation (gain) loss	73.9	73	(199.9)
Benefit obligation at end of year	$ 860.4	$ 756.2	$ 791.2

Pension Benefit Obligations - A

Pension Benefit Obligations - Asset Changes (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Change in plan assets
Fair value of plan assets at beginning of year	$ 772.1
Employer contributions	2.5	$ 3
Fair value of plan assets at end of year	913.3	772.1
United States
Change in plan assets
Fair value of plan assets at beginning of year	98.8	101.4	$ 138.9
Actual return on plan assets	15.8	7.8	(27.2)
Employer contributions	11.9	8.2	9.8
Participant contributions	0.1	0.1	0.1
Benefits and expenses paid	(17.6)	(17.2)	(18.4)
Plan settlements		(1.5)	(1.8)
Fair value of plan assets at end of year	109	98.8	101.4
International
Change in plan assets
Fair value of plan assets at beginning of year	673.3	683.5	1,251.8
Actual return on plan assets	89	(54.2)	(374.5)
Employer contributions	25.1	24.8	23.6
Participant contributions	0.3	0.2	0.3
Benefits and expenses paid	(47.7)	(42.2)	(44.3)
Plan settlements	(3.2)	(1.5)	(2.2)
Foreign currency translation (loss) gain	67.5	62.7	(171.2)
Fair value of plan assets at end of year	$ 804.3	$ 673.3	$ 683.5

Pension Benefit Obligations - F

Pension Benefit Obligations - Funded Status (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
United States
Reconciliation of funded status:
Funded status at end of year	$ (77.9)	$ (82.4)	$ (96.7)
Net amount recognized at end of year	(77.9)	(82.4)	(96.7)
International
Reconciliation of funded status:
Funded status at end of year	(56.1)	(82.9)	(107.7)
Net amount recognized at end of year	$ (56.1)	$ (82.9)	$ (107.7)

Pension Benefit Obligations -_2

Pension Benefit Obligations - Balance Sheet Recognition (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Amounts recognized in the consolidated balance sheets:
Pension benefit obligations	$ (172,360)	$ (195,586)
United States
Amounts recognized in the consolidated balance sheets:
Accrued expenses and other current liabilities	(8,300)	(8,400)	$ (8,600)
Pension benefit obligations	(69,600)	(74,000)	(88,100)
Net amount recognized in the balance sheet	(77,900)	(82,400)	(96,700)
International
Amounts recognized in the consolidated balance sheets:
Other non-current assets	46,600	38,700	36,800
Pension benefit obligations	(102,700)	(121,600)	(144,500)
Net amount recognized in the balance sheet	$ (56,100)	$ (82,900)	$ (107,700)

Pension Benefit Obligations - E

Pension Benefit Obligations - Equity Recognition (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
United States
Reconciliation of amounts in consolidated statements of stockholders' equity:
Prior service cost	$ (0.1)	$ (0.1)	$ (0.1)
Net loss	(77.6)	(77.5)	(91.7)
Total recognized in accumulated other comprehensive loss	(77.7)	(77.6)	(91.8)
International
Reconciliation of amounts in consolidated statements of stockholders' equity:
Prior service cost	(1.3)	(1.2)	(1.2)
Net loss	(234.9)	(207.1)	(187.1)
Total recognized in accumulated other comprehensive loss	$ (236.2)	$ (208.3)	$ (188.3)

Pension Benefit Obligations - P

Pension Benefit Obligations - Periodic Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
United States
Pension Benefit Obligations
Interest cost on projected benefit obligation	$ 9.7	$ 9.8	$ 4.7
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income	Other Nonoperating Income	Other Nonoperating Income
Expected return on plan assets	$ (5.5)	$ (5.8)	$ (5.6)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income	Other Nonoperating Income	Other Nonoperating Income
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income	Other Nonoperating Income	Other Nonoperating Income
Amortization of net loss (gain)	$ 3.1	$ 3.5	$ 5.6
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income	Other Nonoperating Income	Other Nonoperating Income
Settlement loss (gain) recognized		$ (0.1)	$ 0.2
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Settlement Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income	Other Nonoperating Income	Other Nonoperating Income
Net periodic benefit cost (credit)	$ 7.3	$ 7.4	$ 4.9
International
Pension Benefit Obligations
Service costs	0.2	0.3	0.5
Interest cost on projected benefit obligation	$ 43.7	$ 47.7	$ 24.1
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income	Other Nonoperating Income	Other Nonoperating Income
Expected return on plan assets	$ (57.4)	$ (60.8)	$ (41.4)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income	Other Nonoperating Income	Other Nonoperating Income
Amortization of prior service costs	$ 0.1	$ 0.1	$ 0.1
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income	Other Nonoperating Income	Other Nonoperating Income
Amortization of net loss (gain)	$ (2.3)	$ (0.6)	$ 6.9
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income	Other Nonoperating Income	Other Nonoperating Income
Settlement loss (gain) recognized	$ 0.1	$ 0.2	$ 0.3
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Settlement Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income	Other Nonoperating Income	Other Nonoperating Income
Net periodic benefit cost (credit)	$ (15.6)	$ (13.1)	$ (9.5)
Pension Plan, Defined Benefit
Pension Benefit Obligations
Applicable deferred income taxes, included in OCI arising from net prior service cost and net gain/loss	$ 2.1	$ 3.1	$ 18.8

Pension Benefit Obligations -_3

Pension Benefit Obligations - AOCI (Details) $ in Millions	Sep. 30, 2024 USD ($)
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) gain	$ (3.8)
Total	(3.8)
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 cost	(0.1)
Amortization of net actuarial (losses) gain	1.3
Total	$ 1.2

Pension Benefit Obligations -_4

Pension Benefit Obligations - Excess of Plan Assets (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
United States
Additional year-end information for pension plans with accumulated benefit obligations in excess of plan assets
Projected benefit obligation	$ 175.1	$ 168.8	$ 184.8
Accumulated benefit obligation	175.1	168.8	184.8
Fair value of plan assets	109	98.8	101.4
Expected employer contributions in next fiscal year	11.2
International
Additional year-end information for pension plans with accumulated benefit obligations in excess of plan assets
Projected benefit obligation	649.8	628.1	601.4
Accumulated benefit obligation	649.8	628.1	600.1
Fair value of plan assets	547.1	$ 506.5	$ 456.9
Expected employer contributions in next fiscal year	$ 24.2

Pension Benefit Obligations -_5

Pension Benefit Obligations - Future payments (Details) $ in Millions	Sep. 30, 2024 USD ($)
United States
Expected future benefit payments
2025	$ 20.2
2026	19.5
2027	18.3
2028	17.7
2029	16.7
2030-2034	71.2
Total	163.6
International
Expected future benefit payments
2025	54.6
2026	53.9
2027	55.5
2028	57.2
2029	59.2
2030-2034	317.5
Total	$ 597.9

Pension Benefit Obligations - U

Pension Benefit Obligations - Underlying assumptions (Details)	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
United States
Weighted-average assumptions to determine benefit obligation:
Discount rate (as a percent)	4.73%	5.76%	5.40%
Weighted-average assumptions to determine net periodic benefit cost:
Discount rate (as a percent)	5.76%	5.40%	2.46%
Expected long-term rate of return on plan assets (as a percent)	6.90%	7%	6.25%
International
Weighted-average assumptions to determine benefit obligation:
Discount rate (as a percent)	5.04%	5.65%	5.27%
Salary increase rate (as a percent)	2.91%	3.06%	3.48%
Weighted-average assumptions to determine net periodic benefit cost:
Discount rate (as a percent)	5.65%	5.27%	1.98%
Salary increase rate (as a percent)	3.06%	3.48%	3.13%
Expected long-term rate of return on plan assets (as a percent)	5.74%	6.04%	3.93%

Pension Benefit Obligations - T

Pension Benefit Obligations - Target Allocation and Plan Assets Allocations (Details)	Sep. 30, 2024	Sep. 30, 2023
United States
Pension Benefit Obligations
Target allocations (as a percent)	100%
Percentage of Plan Assets (as a percent)	100%	100%
United States | Equities
Pension Benefit Obligations
Target allocations (as a percent)	23%
Percentage of Plan Assets (as a percent)	24%	33%
United States | Debt
Pension Benefit Obligations
Target allocations (as a percent)	70%
Percentage of Plan Assets (as a percent)	67%	56%
United States | Cash
Pension Benefit Obligations
Target allocations (as a percent)	3%
Percentage of Plan Assets (as a percent)	4%	2%
United States | Diversified and other
Pension Benefit Obligations
Target allocations (as a percent)	4%
Percentage of Plan Assets (as a percent)	5%	9%
International
Pension Benefit Obligations
Target allocations (as a percent)	100%
Percentage of Plan Assets (as a percent)	100%	100%
International | Equities
Pension Benefit Obligations
Target allocations (as a percent)	22%
Percentage of Plan Assets (as a percent)	25%	24%
International | Debt
Pension Benefit Obligations
Target allocations (as a percent)	65%
Percentage of Plan Assets (as a percent)	64%	62%
International | Cash
Pension Benefit Obligations
Target allocations (as a percent)	4%
Percentage of Plan Assets (as a percent)	2%	4%
International | Diversified and other
Pension Benefit Obligations
Target allocations (as a percent)	9%
Percentage of Plan Assets (as a percent)	9%	10%

Pension Benefit Obligations -_6

Pension Benefit Obligations - Asset Categories (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Post-retirement plan
Fair values of plan assets	$ 913.3	$ 772.1
Cash and cash equivalents
Post-retirement plan
Fair values of plan assets	22.1	29.5
Debt securities
Post-retirement plan
Fair values of plan assets	391.5	338.3
Diversified and equity funds
Post-retirement plan
Fair values of plan assets	286.7	258.4
Fixed income funds
Post-retirement plan
Fair values of plan assets	213.9	174.3
Absolute return fund
Post-retirement plan
Fair values of plan assets	5.9	8.9
Derivative instruments and other
Post-retirement plan
Fair values of plan assets	(6.8)	(37.3)
Quoted Prices in Active Markets (Level 1)
Post-retirement plan
Fair values of plan assets	487.6	412
Quoted Prices in Active Markets (Level 1) | Cash and cash equivalents
Post-retirement plan
Fair values of plan assets	22.1	20.2
Quoted Prices in Active Markets (Level 1) | Debt securities
Post-retirement plan
Fair values of plan assets	391.5	338.3
Quoted Prices in Active Markets (Level 1) | Diversified and equity funds
Post-retirement plan
Fair values of plan assets	48.5	30.3
Quoted Prices in Active Markets (Level 1) | Fixed income funds
Post-retirement plan
Fair values of plan assets	17.3	21.7
Quoted Prices in Active Markets (Level 1) | Derivative instruments and other
Post-retirement plan
Fair values of plan assets	8.2	1.5
Significant Other Observable Inputs (Level 2)
Post-retirement plan
Fair values of plan assets	2.6	(11.9)
Significant Other Observable Inputs (Level 2) | Cash and cash equivalents
Post-retirement plan
Fair values of plan assets		9.3
Significant Other Observable Inputs (Level 2) | Diversified and equity funds
Post-retirement plan
Fair values of plan assets	13.5	13.2
Significant Other Observable Inputs (Level 2) | Fixed income funds
Post-retirement plan
Fair values of plan assets	4.1	4.4
Significant Other Observable Inputs (Level 2) | Derivative instruments and other
Post-retirement plan
Fair values of plan assets	(15)	(38.8)
Investments measured at NAV
Post-retirement plan
Fair values of plan assets	423.1	372
Investments measured at NAV | Diversified and equity funds
Post-retirement plan
Fair values of plan assets	224.7	214.9
Investments measured at NAV | Fixed income funds
Post-retirement plan
Fair values of plan assets	192.5	148.2
Investments measured at NAV | Absolute return fund
Post-retirement plan
Fair values of plan assets	$ 5.9	$ 8.9

Pension Benefit Obligations - M

Pension Benefit Obligations - Multiemployer (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Pension Benefit Obligations
Aggregate contributions to these multiemployer plans	$ 2.5	$ 3

Debt - Long-term debt (Details)

Debt - Long-term debt (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023
Debt
Total debt	$ 2,539,800	$ 2,217,300
Less: Current portion of debt and short-term borrowings	(66,900)	(89,500)
Less: Unamortized debt issuance costs	(22,600)	(14,400)
Long-term debt	2,450,330	2,113,369
Credit Agreement
Debt
Total debt	1,446,600	1,119,800
2027 Senior Notes
Debt
Total debt	997,300	997,300
Other Debt
Debt
Total debt	$ 95,900	$ 100,200

Debt - Scheduled Maturities Of

Debt - Scheduled Maturities Of Debt (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Debt
2025	$ 66.9
2026	27.1
2027	1,016.5
2028	9.6
2029	756.8
Thereafter	662.9
Total	$ 2,539.8	$ 2,217.3

Debt - Credit Agreement (Detail

Debt - Credit Agreement (Details) - Credit Agreement - USD ($)	Apr. 19, 2024	Sep. 30, 2024	Sep. 30, 2023
Maximum
Debt agreements
Consolidated leverage ratio	4
New Revolving Credit Facility
Debt agreements
Maximum borrowing capacity	$ 1,500,000,000
New Revolving Credit Facility | Other Currency
Debt agreements
Interest rate, basis spread (as a percent)	1.225%
New Term Loan A Facility
Debt agreements
Maximum borrowing capacity	$ 750,000,000
New Term Loan B Facility
Debt agreements
Maximum borrowing capacity	$ 700,000,000
New Term Loan B Facility | SOFR
Debt agreements
Debt instrument, floor rate	0%
Debt instrument, spread adjustment rate	0%
Interest rate, basis spread (as a percent)	1.75%
New Term Loan B Facility | Base Rate
Debt agreements
Debt instrument, floor rate	0%
Interest rate, basis spread (as a percent)	0.75%
Revolving credit facility
Debt agreements
Outstanding letters of credit		$ 4,400,000	$ 4,400,000
Current borrowing capacity		$ 1,495,600,000	$ 1,145,600,000
New Revolving Credit Facility and New Term A Facility | SOFR | USD
Debt agreements
Debt instrument, floor rate	0%
Debt instrument, spread adjustment rate	0.10%
Interest rate, basis spread (as a percent)	1.225%
New Revolving Credit Facility and New Term A Facility | Base Rate | USD
Debt agreements
Debt instrument, floor rate	0%
Interest rate, basis spread (as a percent)	0.25%

Debt - 2027 Senior Notes (Detai

Debt - 2027 Senior Notes (Details) - 2027 Senior Notes - USD ($)	Feb. 21, 2017	Sep. 30, 2024
Debt
Face amount	$ 1,000,000,000
Interest rate (as a percent)	5.125%
Fair value of debt instrument		$ 997,300,000
At any time and from time to time prior to December 15, 2026
Debt
Redemption price (in percent)	100%
On or after December 15, 2026
Debt
Redemption price (in percent)	100%

Debt - Other Debt and Other Ite

Debt - Other Debt and Other Items (Details) - Other Debt - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Unsecured
Debt
Current borrowing capacity	$ 389.8
Standby Letters of Credit
Debt
Outstanding letters of credit	$ 934.5	$ 878.9

Debt - Effective Interest Rate

Debt - Effective Interest Rate (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Debt
Effective interest rate including effects of interest rate swap agreements	5.60%	5.30%	3.80%
Amortization of deferred debt issuance costs	$ 7.6	$ 4.9	$ 4.9

Derivative Financial Instrume_3

Derivative Financial Instruments and Fair Value Measurements - Cash Flow Hedges (Details) - Cash Flow Hedging - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023	Jun. 30, 2022	Sep. 30, 2021
Interest Rate Cap
Derivative financial instruments
Notional Amount			$ 300
Fixed Rate (as a percent)			3.465%
Interest Rate Cap | Maximum
Derivative financial instruments
Fixed Rate (as a percent)			3.465%
Interest Rate Swap
Derivative financial instruments
Notional Amount				$ 400
Fixed Rate (as a percent)				1.283%
Designated as Hedging Instrument | Interest Rate Swap | USD | February 2023
Derivative financial instruments
Notional Amount	$ 400	$ 400
Fixed Rate (as a percent)	1.283%	1.283%

Derivative Financial Instrume_4

Derivative Financial Instruments and Fair Value Measurements - Fair Value Measurements (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Fair Value, Measurements, Recurring
Derivative financial instruments
Total net assets at fair value	$ 62.5	$ 54.7
Fair Value, Measurements, Recurring | Other non-current assets
Derivative financial instruments
Equity investment	19.4
Interest rate contract | Fair Value, Measurements, Recurring | Other current assets
Derivative financial instruments
Derivative asset	9.2	17.2
Interest rate contract | Fair Value, Measurements, Recurring | Other non-current assets
Derivative financial instruments
Derivative asset	16.5	37.5
Interest rate contract | Fair Value, Measurements, Recurring | Other current liabilities
Derivative financial instruments
Derivative liability	(0.9)
Interest rate contract | Fair Value, Measurements, Recurring | Other long-term liabilities
Derivative financial instruments
Derivative liability	(3.6)
Credit facility investment
Derivative financial instruments
Gain representing increase in fair value	7.2
Credit facility investment | Fair Value, Measurements, Recurring | Other non-current assets
Derivative financial instruments
Alternative Investment	21.9
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring
Derivative financial instruments
Total net assets at fair value	19.4
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Other non-current assets
Derivative financial instruments
Equity investment	19.4
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Derivative financial instruments
Total net assets at fair value	21.2	54.7
Significant Other Observable Inputs (Level 2) | Interest rate contract | Fair Value, Measurements, Recurring | Other current assets
Derivative financial instruments
Derivative asset	9.2	17.2
Significant Other Observable Inputs (Level 2) | Interest rate contract | Fair Value, Measurements, Recurring | Other non-current assets
Derivative financial instruments
Derivative asset	16.5	$ 37.5
Significant Other Observable Inputs (Level 2) | Interest rate contract | Fair Value, Measurements, Recurring | Other current liabilities
Derivative financial instruments
Derivative liability	(0.9)
Significant Other Observable Inputs (Level 2) | Interest rate contract | Fair Value, Measurements, Recurring | Other long-term liabilities
Derivative financial instruments
Derivative liability	(3.6)
Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring
Derivative financial instruments
Total net assets at fair value	21.9
Significant Unobservable Inputs (Level 3) | Credit facility investment | Fair Value, Measurements, Recurring | Other non-current assets
Derivative financial instruments
Alternative Investment	$ 21.9

Derivative Financial Instrume_5

Derivative Financial Instruments and Fair Value Measurements - Fair Value Measurements - Changes in fair value of the Company's Level 3 investment assets (Details) - Credit facility investment including accrued interest - Level 3 - Fair Value, Measurements, Recurring $ in Millions	12 Months Ended
	Sep. 30, 2024 USD ($)
Derivative financial instruments
Investment Gains/(Losses)	$ 0.5
Interest Earned	0.5
Purchases	32.5
Sales	(11.6)
Ending Balance	$ 21.9

Leases - Components of lease ex

Leases - Components of lease expense (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Leases
Impairment of leasehold and right of use assets	$ 86.2
Operating lease cost
Operating lease cost		$ 149.1	$ 164	$ 172.5
Finance lease cost:
Amortization of right-of-use assets		28.4	23.1	18
Interest on lease liabilities		2.9	2.6	2.2
Variable lease cost		34.6	34.1	34
Total lease cost		$ 215	$ 223.8	$ 226.7

Leases - Additional balance she

Leases - Additional balance sheet information (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Assets:
Operating lease assets	$ 432,166	$ 447,044
Balance Sheet classification of operating lease assets	Operating lease assets	Operating lease assets
Finance lease assets	$ 62,100	$ 64,800
Balance Sheet classification of finance lease assets	PROPERTY AND EQUIPMENT-NET	PROPERTY AND EQUIPMENT-NET
Total lease assets	$ 494,300	$ 511,800
Current:
Operating lease liabilities	$ 135,100	$ 139,800
Balance Sheet classification of operating lease liabilities	Accrued expenses and other current liabilities	Accrued expenses and other current liabilities
Finance lease liabilities	$ 25,500	$ 25,000
Balance Sheet classification of finance lease liabilities	Current portion of long-term debt	Current portion of long-term debt
Total current lease liabilities	$ 160,600	$ 164,800
Non-current:
Operating lease liabilities	$ 510,573	$ 548,851
Balance Sheet classification of operating lease liabilities	Operating lease liabilities	Operating lease liabilities
Finance lease liabilities	$ 35,700	$ 39,800
Balance Sheet classification of finance lease liabilities	LONG-TERM DEBT	LONG-TERM DEBT
Total non-current lease liabilities	$ 546,300	$ 588,700
Weighted average remaining lease term (in years):
Operating leases	6 years 2 months 12 days	6 years 4 months 24 days	6 years 6 months
Finance leases	2 years 7 months 6 days	2 years 10 months 24 days	3 years 1 month 6 days
Weighted average discount rates:
Operating leases	5.10%	4.30%	4%
Finance leases	4.40%	4.10%	3.80%

Leases - Additional cash flow i

Leases - Additional cash flow information (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 184.9	$ 188.3	$ 201.8
Operating cash flows from finance leases	3	2.5	2.2
Financing cash flows from finance leases	28.9	23.7	19.8
Right-of-use assets obtained in exchange for new operating leases	90.1	96.6	90.9
Right-of-use assets obtained in exchange for new finance leases	$ 26.6	$ 37.5	$ 26.2

Leases - Lease payments under o

Leases - Lease payments under operating lease (Details) $ in Millions	Sep. 30, 2024 USD ($)
Amounts payable under non-cancelable operating lease commitments
2025	$ 164.4
2026	135.2
2027	104.1
2028	90.4
2029	75
Thereafter	187.1
Total lease payments	756.2
Less: Amounts representing interest	(110.5)
Total lease liabilities	$ 645.7

Leases - Lease payments under f

Leases - Lease payments under finance lease (Details) $ in Millions	Sep. 30, 2024 USD ($)
Leases
2025	$ 27.7
2026	21.6
2027	12.9
2028	2.9
2029	0.1
Total lease payments	65.2
Less: Amounts representing interest	(4)
Total lease liabilities	$ 61.2

Share-Based Payments - Defined

Share-Based Payments - Defined Contribution Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Share-based Payments
Compensation expense under defined contribution plans	$ 24.7	$ 23.1	$ 22.7

Share-Based Payments - Stock In

Share-Based Payments - Stock Incentive Plans (Details) - 2020 Stock Incentive Plan shares in Millions	12 Months Ended
	Sep. 30, 2024 shares
Share-based Payments
Securities available for future issuance (in shares)	11.7
Employee Stock Option
Share-based Payments
Expiration term of unexercised options	7 years

Share-based Payments - Restrict

Share-based Payments - Restricted stock units and PEP units activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Other disclosures
Compensation expense related to share-based payments	$ 61.5	$ 45.9	$ 38.5
Unrecognized compensation expense	$ 68.7	$ 48.3
Recognition period of unrecognized compensation expense	3 years	3 years
Restricted Stock Units
Units
Outstanding at beginning (in units)	800,000	1,000,000	1,300,000
Granted (in units)	300,000	300,000	300,000
Vested (in shares)	(300,000)	(400,000)	(500,000)
Cancelled (in shares)		(100,000)	(100,000)
Outstanding at ending (in units)	800,000	800,000	1,000,000
Weighted Average Grant-Date Fair Value
Outstanding at beginning (in USD per unit)	$ 68.34	$ 53.05	$ 38.88
Granted (in USD per unit)	92.30	83.64	74.30
Vested (in USD per unit)	50.14	44.35	29.44
Cancelled (in USD per unit)	77.32	62.09	49.74
Outstanding at ending (in USD per unit)	$ 83.96	$ 68.34	$ 53.05
PEP Units
Units
Outstanding at beginning (in units)	700,000	700,000	1,200,000
Granted (in units)	200,000	200,000	200,000
PEP units earned (unearned) (in shares)	200,000	200,000	600,000
Vested (in shares)	(400,000)	(400,000)	(1,300,000)
Outstanding at ending (in units)	700,000	700,000	700,000
Weighted Average Grant-Date Fair Value
Outstanding at beginning (in USD per unit)	$ 75.54	$ 60.60	$ 37.22
Granted (in USD per unit)	104.66	94.64	85.46
PEP units earned (unearned) (in USD per share)	52.50	43.19	27.90
Vested (in USD per unit)	52.50	43.19	27.90
Cancelled (in USD per unit)	89.76	71.71	56.64
Outstanding at ending (in USD per unit)	$ 95.38	$ 75.54	$ 60.60

Share-Based Payments - PEP, RSU

Share-Based Payments - PEP, RSU (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Information concerning outstanding and exercisable options
Compensation expense related to share-based payments	$ 61.5	$ 45.9	$ 38.5
Unrecognized compensation expense	$ 68.7	$ 48.3
Recognition period of unrecognized compensation expense	3 years	3 years
Performance Earnings Program | PEP Units
Information concerning outstanding and exercisable options
Vesting period	3 years

Income Taxes - Tax (Benefit) Ex

Income Taxes - Tax (Benefit) Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Income Taxes
Income from domestic operations before income tax expense	$ 233,000	$ 129,200	$ 235,200
Income from foreign operations before income tax expense	485,200	342,600	315,400
Current:
Federal	15,100	67,700	22,800
State	(78,600)	71,900	16,000
Foreign	63,500	52,800	75,800
Total current income tax expense		192,400	114,600
Deferred:
Federal	45,200	(71,800)	22,100
State	68,100	(84,300)	11,800
Foreign	39,600	19,800	(12,400)
Total deferred income tax expense (benefit)	152,900	(136,300)	21,500
Total income tax expense	$ 152,900	$ 56,052	$ 136,051

Income Taxes - Federal Rate Rec

Income Taxes - Federal Rate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Income Taxes
Tax expense related to valuation allowances	$ (10,300)
Rate reconciliation
Tax at federal statutory rate	150,800	$ 44,800	$ 115,600
State income tax, net of federal benefit	(8,500)	(7,100)	20,200
Foreign residual income	43,800	59,400	46,400
Nondeductible costs	20,600	10,700	19,700
ACAP investment sale	20,200
Change in uncertain tax positions	18,600	9,400	15,400
Tax rate changes	1,200	(3,200)	(4,100)
Audit settlement	500	1,900	(1,500)
Income tax credits and incentives	(63,500)	(68,200)	(51,000)
Valuation allowance	(12,600)	16,600	(18,000)
Exclusion of tax on non-controlling interests	(12,500)	(9,400)	(5,100)
Return to provision	(3,700)	(500)	(1,500)
Foreign tax rate differential	(2,800)	200	1,100
Tax exempt income	(2,500)	(3,300)	(5,900)
Other items, net	3,300	4,800	4,800
Total income tax expense	$ 152,900	$ 56,052	$ 136,051
Major elements contributing to the difference between the U.S. federal statutory rate of 21% for fiscal year 2022, 2021 and 2020 and the effective tax rate
Tax at federal statutory rate (as a percent)	21%	21%	21%
State income tax, net of federal benefit (as a percent)	(1.20%)	(3.30%)	3.70%
Foreign residual income (as a percent)	6.10%	27.80%	8.40%
Nondeductible costs (as a percent)	2.90%	5%	3.60%
ACAP investment sale (as a percent)	2.80%
Change in uncertain tax positions (as a percent)	2.60%	4.40%	2.80%
Tax rate changes (as a percent)	0.20%	(1.50%)	(0.70%)
Audit settlement (as a percent)	0.10%	0.90%	(0.30%)
Income tax credits and incentive (as a percent)	(8.80%)	(31.90%)	(9.30%)
Valuation allowance (as a percent)	(1.80%)	7.80%	(3.30%)
Exclusion of tax on non-controlling interests (as a percent)	(1.70%)	(4.40%)	(0.90%)
Return to provision (as a Percent)	(0.50%)	(0.20%)	(0.30%)
Foreign tax rate differential (as a percent)	(0.40%)	0.10%	0.20%
Tax exempt income (as a percent)	(0.40%)	(1.50%)	(1.10%)
Other items, net (as a percent)	0.40%	2.10%	0.90%
Total income tax expense (as a percent)	21.30%	26.30%	24.70%

Income Taxes - Additional infor

Income Taxes - Additional information (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Income taxes
Increase in tax benefit	$ 38.4
Increase in tax expense related to uncertain tax position	23
Increase (decrease) in valuation allowance	(10.3)
Tax expense (benefit) related to uncertain tax positions	18.6	$ 9.4	$ 15.4
Valuation allowance	160.9	171.2
ACAP Investments
Income taxes
Increase (decrease) in valuation allowance	(21)
Reduction in deferred tax assets	20.2
Valuation allowance	9.3
AECOM Capital impairment charge
Income taxes
Valuation allowance		$ 21
CANADA | Net operating losses and other deferred tax assets
Income taxes
Increase (decrease) in valuation allowance	(11.7)
HONG KONG
Income taxes
Tax expense (benefit) related to uncertain tax positions	(6.9)
Foreign | Net operating losses and other deferred tax assets
Income taxes
Increase (decrease) in valuation allowance			$ (21.9)
UNITED STATES | ACAP Investments
Income taxes
Increase (decrease) in valuation allowance	$ (11.7)

Income Taxes - Deferred tax (De

Income Taxes - Deferred tax (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Deferred tax assets:
Compensation and benefit accruals not currently deductible	$ 85.4	$ 92.2
Net operating loss carryforwards	107.5	102.3
Self-insurance reserves	38.3	23.2
Research and experimentation and other tax credits	67.1	43.1
Pension liability	34.9	44.7
Accrued liabilities	265.7	295.1
Capital loss carryforward	49.5	64
Partnership investment	22.3	102
Other	8.2	7.1
Total deferred tax assets	678.9	773.7
Deferred tax liabilities:
Unearned revenue	(4.1)	(7)
Depreciation and amortization	(83.7)	(13.1)
Acquired intangible assets		(5.4)
Investment in subsidiaries	(9.9)	(10.7)
Right of use assets	(85.2)	(94)
Contingent consideration	(30.5)	(34.2)
Other	(5.4)	(15.5)
Total deferred tax liabilities	(218.8)	(179.9)
Valuation allowance	(160.9)	(171.2)
Net deferred tax assets	299.2	422.6
Income Taxes, additional disclosures
Net operating loss carryforwards	744.6	757.5
Gross tax asset exclusive of tax liabilities realizable	518
Increase (decrease) in valuation allowance	(10.3)
Gross book-tax differences from non-U.S. subsidiaries	1,200
Liability for unrecognized tax benefits, including potential interest and penalties, net of related tax benefit	97.9	79.5
Unrecognized tax benefits	81.3	62.1	$ 55.2
Unrecognized tax benefits that would be included in the effective tax rate if recognized	77.1
ACAP investment sale
Deferred tax liabilities:
Valuation allowance	(9.3)
Income Taxes, additional disclosures
Increase (decrease) in valuation allowance	(21)
Capital losses
Income Taxes, additional disclosures
Increase (decrease) in valuation allowance	(10.4)
Foreign net operating losses and currency translation adjustments
Income Taxes, additional disclosures
Increase (decrease) in valuation allowance	12.3
State net operating losses and credits
Income Taxes, additional disclosures
Increase (decrease) in valuation allowance	(0.6)
UNITED STATES | ACAP investment sale
Income Taxes, additional disclosures
Increase (decrease) in valuation allowance	(11.7)
Capital loss carryforwards
Income Taxes, additional disclosures
Tax credit carryforward	181.2	$ 199.4
Other credits
Income Taxes, additional disclosures
Tax credit carryforward	9.7
Federal | Research and development credits
Income Taxes, additional disclosures
Tax credit carryforward	28.4
State | Research and development credits
Income Taxes, additional disclosures
Tax credit carryforward	27.8
Foreign | Research and development credits
Income Taxes, additional disclosures
Tax credit carryforward	$ 4.6

Income Taxes - Gross Unrecogniz

Income Taxes - Gross Unrecognized (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Reconciliation of the beginning and ending amount of gross unrecognized tax benefits
Balance at the beginning of the year	$ 62.1	$ 55.2
Gross increase in current period's tax positions	34.5	3.5
Gross increase in prior years' tax positions	13.9	17.9
Gross decrease in prior years' tax positions	(20.1)	(13.3)
Decrease due to settlement with tax authorities	(7.4)	(1)
Decrease due to lapse of statute of limitations	(2.2)
Gross change due to foreign exchange fluctuations	0.5	(0.2)
Balance at the end of the year	81.3	62.1
Income Taxes, additional disclosures
Accrued interest, excluding any related income tax benefits	27.7	24.4
Accrued penalties, excluding any related income tax benefits	$ 3.5	$ 1.5

Earnings Per Share (Details)

Earnings Per Share (Details) - shares shares in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Earnings Per Share
Denominator for basic earnings per share	135,544	138,614	140,768
Potential common shares	1,000	1,500	1,900
Denominator for diluted earnings per share	136,453	140,109	142,696

Other Financial Information (De

Other Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022	Sep. 12, 2024
Accrued expenses and other current liabilities
Accrued salaries and benefits	$ 620,400	$ 599,800
Accrued contract costs	1,354,700	1,340,400
Other accrued expenses	410,600	347,300
Total	2,385,731	2,287,546
Restructuring costs	98,918	188,404	$ 107,501
Accrued restructuring expenses	11,900	53,300
Dividend paid per share in cash				$ 0.22
Accrued and unpaid dividend	31,900
Labor-related costs
Accrued expenses and other current liabilities
Restructuring costs	18,700	91,600
Non-labor costs
Accrued expenses and other current liabilities
Restructuring costs	80,200
Real estate costs
Accrued expenses and other current liabilities
Restructuring costs		96,800
Professional liability accrual
Accrued expenses and other current liabilities
Accrued contract costs	$ 831,800	$ 809,600

Reclassifications out of Accu_3

Reclassifications out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Accumulated balances
Balance at the beginning of the period	$ (926,577)
Balance at the end of the period	(882,671)	$ (926,577)
Pension Related Adjustments
Accumulated balances
Balance at the beginning of the period	(226,000)	(217,300)	$ (316,200)
Other comprehensive income (loss) before reclassification	(26,600)	(10,900)	89,900
Amounts reclassified from accumulated other comprehensive loss	600	2,200	9,000
Balance at the end of the period	(252,000)	(226,000)	(217,300)
Foreign Currency Translation Adjustments
Accumulated balances
Balance at the beginning of the period	(739,700)	(799,300)	(580,100)
Other comprehensive income (loss) before reclassification	93,200	59,600	(238,700)
Amounts reclassified from accumulated other comprehensive loss			19,500
Balance at the end of the period	(646,500)	(739,700)	(799,300)
Loss on Derivative Instruments
Accumulated balances
Balance at the beginning of the period	39,100	36,900	(4,100)
Other comprehensive income (loss) before reclassification	(10,600)	10,700	37,900
Amounts reclassified from accumulated other comprehensive loss	(12,700)	(8,500)	3,100
Balance at the end of the period	15,800	39,100	36,900
Accumulated Other Comprehensive Loss
Accumulated balances
Balance at the beginning of the period	(926,600)	(979,700)	(900,400)
Other comprehensive income (loss) before reclassification	56,000	59,400	(110,900)
Amounts reclassified from accumulated other comprehensive loss	(12,100)	(6,300)	31,600
Balance at the end of the period	$ (882,700)	$ (926,600)	$ (979,700)

Commitments and Contingencies -

Commitments and Contingencies - Commitments (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Standby letters of credit
Commitments and Contingencies
Outstanding standby letters of credit	$ 934.5	$ 878.9
Amount available under letters of credit	389.8
Contingency liability	938.9
Surety Bond
Commitments and Contingencies
Contingency liability	5,100
Fund investment capital
Commitments and Contingencies
Commitment	$ 5.9
Commitment period	4 years

Commitments and Contingencies_2

Commitments and Contingencies - DOE Project (Details) - Task order to provide deactivation, demolition and removal services at New York State project site - USD ($) $ in Millions	Jan. 31, 2020	Dec. 06, 2019	Sep. 30, 2024	Dec. 31, 2014
Commitments and Contingencies
Percentage of claim recoveries due to purchaser	10%
Percentage of claim recoveries due to seller	90%
Former Affiliate
Commitments and Contingencies
Minimum project cost to pay			$ 146
Department of Energy
Commitments and Contingencies
Maximum project cost to pay			106
Additional fees on changed work scope		$ 60.4		$ 103
Former Affiliate and DOE
Commitments and Contingencies
Maximum project cost to pay			146
Minimum project cost to pay			$ 106
Former Affiliate | Department of Energy | Minimum
Commitments and Contingencies
Damages sought		148.5
Former Affiliate | Department of Energy | Maximum
Commitments and Contingencies
Damages sought		$ 329.4

Commitments and Contingencies_3

Commitments and Contingencies - Refinery Turnaround Project (Details) - Refinery Turnaround Project - USD ($) $ in Millions	1 Months Ended
	Dec. 31, 2019	Apr. 30, 2019	Mar. 31, 2019	Sep. 30, 2024
Commitments and Contingencies
Amount of work outside original contract				$ 90
Payment entitled to				$ 144
Construction lien against the refinery for unpaid labor and materials costs		$ 132
A Refinery in Montana
Commitments and Contingencies
Damages sought, counter party	$ 93		$ 79

Reportable Segments and Geogr_3

Reportable Segments and Geographic Information - Summarized financial information (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2024 USD ($) segment	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)
Summarized financial information concerning the Company's reportable segments
Number of reportable segments | segment	3
Revenue	$ 16,105,498	$ 14,378,461	$ 13,148,182
Gross profit	1,084,341	945,465	847,974
Equity in earnings of joint ventures	2,124	(279,352)	53,640
General and administrative expenses	(160,105)	(153,575)	(147,309)
Restructuring costs	(98,918)	(188,404)	(107,501)
Operating income	827,442	324,134	646,804
Segment assets	12,061,669	11,233,398
Total
Summarized financial information concerning the Company's reportable segments
Revenue	16,105,500	14,378,500	13,148,200
Gross profit	1,084,300	945,500	848,000
Equity in earnings of joint ventures	2,100	(279,400)	53,600
General and administrative expenses	(160,100)	(153,600)	(147,300)
Restructuring costs	(98,900)	(188,400)	(107,500)
Operating income	$ 827,400	$ 324,100	$ 646,800
Gross profit as a % of revenue	6.70%	6.60%	6.40%
Operating Segments | Americas
Summarized financial information concerning the Company's reportable segments
Revenue	$ 12,485,700	$ 10,975,700	$ 9,939,300
Gross profit	759,100	699,700	639,900
Equity in earnings of joint ventures	15,500	14,900	13,900
Operating income	774,600	714,600	653,800
Segment assets	$ 7,988,100	$ 7,433,100	$ 7,232,200
Gross profit as a % of revenue	6.10%	6.40%	6.40%
Operating Segments | International
Summarized financial information concerning the Company's reportable segments
Revenue	$ 3,618,400	$ 3,402,100	$ 3,206,700
Gross profit	323,800	245,100	205,900
Equity in earnings of joint ventures	13,500	9,600	15,300
Operating income	337,300	254,700	221,200
Segment assets	$ 2,734,500	$ 2,536,200	$ 2,467,900
Gross profit as a % of revenue	8.90%	7.20%	6.40%
Operating Segments | AECOM Capital
Summarized financial information concerning the Company's reportable segments
Revenue	$ 1,400	$ 700	$ 2,200
Gross profit	1,400	700	2,200
Equity in earnings of joint ventures	(26,900)	(303,900)	24,400
General and administrative expenses	(15,000)	(12,600)	(12,600)
Operating income	(40,500)	(315,800)	14,000
Segment assets	53,200	64,500	264,900
Corporate
Summarized financial information concerning the Company's reportable segments
General and administrative expenses	(145,100)	(141,000)	(134,700)
Restructuring costs	(98,900)	(188,400)	(107,500)
Operating income	(244,000)	(329,400)	(242,200)
Segment assets	$ 1,208,700	$ 1,104,400	$ 1,095,300

Reportable Segments and Geogr_4

Reportable Segments and Geographic Information - Geographic Information (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Geographic Information
Long-Lived Assets	$ 4,558.9	$ 4,624.3	$ 5,032.4
Americas
Geographic Information
Long-Lived Assets	3,315.3	3,478.5	3,906.7
Europe, Middle East India, Africa
Geographic Information
Long-Lived Assets	872.9	803.5	763.6
Asia-Australia-Pacific
Geographic Information
Long-Lived Assets	$ 370.7	$ 342.3	$ 362.1

Major Clients (Details)

Major Clients (Details) - Revenue - Customer concentration risk	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Percentage of total revenue
Period for which criteria of threshold percentage for disclosure not met in past	5 years
Minimum
Percentage of total revenue
Percentage of revenue accounted for by no other single client (as a percent)	10%
Agencies of U.S. Federal Government
Percentage of total revenue
Concentration (as a percent)	7%	5%	6%

Schedule II_ Valuation and Qu_2

Schedule II: Valuation and Qualifying Accounts (Details) - SEC Schedule, 12-09, Allowance, Credit Loss - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Changes in valuation and qualifying accounts
Balance at Beginning of Year	$ 94.2	$ 104	$ 92.8
Additions Charged to Cost of Revenue	30.9	40.9	43.9
Deductions	(38.7)	(50.8)	(29.6)
Other and Foreign Exchange Impact	1.5	0.1	(3.1)
Balance at the End of the Year	$ 87.9	$ 94.2	$ 104