Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Income Statement [Abstract]
Revenue	$ 4,014,152	$ 3,899,920
Cost of revenue	3,745,748	3,655,950
Gross profit	268,404	243,970
Equity in earnings (losses) of joint ventures	9,553	(28,941)
General and administrative expenses	(40,459)	(35,724)
Restructuring costs	0	(16,180)
Income from operations	237,498	163,125
Other income	6,924	2,569
Interest income	16,564	12,102
Interest expense	(43,034)	(41,257)
Income from continuing operations before taxes	217,952	136,539
Income tax expense for continuing operations	29,232	26,658
Net income from continuing operations	188,720	109,881
Net loss from discontinued operations	(9,516)	(1,287)
Net income	179,204	108,594
Net income attributable to noncontrolling interests from continuing operations	(11,370)	(13,117)
Net income attributable to noncontrolling interests from discontinued operations	(792)	(1,039)
Net income attributable to noncontrolling interests	(12,162)	(14,156)
Net income attributable to AECOM from continuing operations	177,350	96,764
Net loss attributable to AECOM from discontinued operations	(10,308)	(2,326)
Net income attributable to AECOM	$ 167,042	$ 94,438
Net income (loss) attributable to AECOM per share:
Basic continuing operations per share (in dollar per share)	$ 1.34	$ 0.71
Basic discontinued operations per share (in dollar per share)	(0.08)	(0.02)
Basic earnings per share (in dollar per share)	1.26	0.69
Diluted continuing operations per share (in dollar per share)	1.33	0.71
Diluted discontinued operations per share (in dollar per share)	(0.08)	(0.02)
Diluted earnings per share (in dollar per share)	$ 1.25	$ 0.69
Weighted average shares outstanding:
Basic (in shares)	132,500	135,897
Diluted (in shares)	133,625	137,101