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