Consolidated Statements of Stockholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Total AECOM Stockholders' Equity	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Retained Earnings	Non-Controlling Interests	Convertible Preferred Stock Preferred Stock
BALANCE at Sep. 30, 2010	$ 2,138,469	$ 2,090,012	$ 1,153	$ 1,585,044	$ (147,521)	$ 651,105	$ 48,457	$ 231
Increase (Decrease) in Stockholders' Equity
Net income (loss)	284,090	275,800				275,800	8,290
Other comprehensive income (loss)	(40,053)	(40,053)			(40,053)
Issuance of stock	88,531	88,531	36	88,495
Repurchases of stock	(167,044)	(167,044)	(70)	(66,784)		(99,957)		(233)
Preferred stock dividend						(2)		2
Proceeds from exercise of options	6,280	6,280	5	6,275
Tax benefit from exercise of stock options	61,248	61,248		61,248
Stock based compensation	24,937	24,937	8	24,929
Other transactions with noncontrolling interests	(20)						(20)
Contributions from noncontrolling interests	1,700						1,700
Distributions to noncontrolling interests	(3,001)						(3,001)
BALANCE at Sep. 30, 2011	2,395,137	2,339,711	1,132	1,699,207	(187,574)	826,946	55,426
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(56,933)	(58,567)				(58,567)	1,634
Other comprehensive income (loss)	8,401	8,401			8,401
Issuance of stock	18,631	18,631	9	18,622
Repurchases of stock	(169,454)	(169,454)	(83)	(7,081)		(162,290)
Proceeds from exercise of options	4,541	4,541	4	4,537
Tax benefit from exercise of stock options	(350)	(350)		(350)
Stock based compensation	26,551	26,551	8	26,543
Other transactions with noncontrolling interests	(753)						(753)
Distributions to noncontrolling interests	(1,283)						(1,283)
BALANCE at Sep. 30, 2012	2,224,488	2,169,464	1,070	1,741,478	(179,173)	606,089	55,024
Increase (Decrease) in Stockholders' Equity
Net income (loss)	243,196	239,243				239,243	3,953
Other comprehensive income (loss)	(83,455)	(82,126)			(82,126)		(1,329)
Issuance of stock	28,351	28,351	11	28,340
Repurchases of stock	(381,704)	(381,704)	(147)	(8,380)		(373,177)
Proceeds from exercise of options	14,365	14,365	8	14,357
Tax benefit from exercise of stock options	1,239	1,239		1,239
Stock based compensation	32,611	32,611	18	32,593
Other transactions with noncontrolling interests	13,488						13,488
Contributions from noncontrolling interests	1,421						1,421
Distributions to noncontrolling interests	(19,906)						(19,906)
BALANCE at Sep. 30, 2013	$ 2,074,094	$ 2,021,443	$ 960	$ 1,809,627	$ (261,299)	$ 472,155	$ 52,651