Condensed Consolidated Statements of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 29, 2014	Jun. 30, 2013	Jun. 29, 2014	Jun. 30, 2013
Condensed Consolidated Statements of Comprehensive Income
Net income (loss) including noncontrolling interests	$ 26,711	$ (78,115)	$ 85,946	$ (26,847)
Other comprehensive income (loss):
Foreign currency translation adjustments, net of tax	19,177	(22,430)	(18,642)	(40,197)
(Loss) gain on cash flow hedge valuations, net of tax	(645)		(206)	93
Other comprehensive income (loss)	18,532	(22,430)	(18,848)	(40,104)
Comprehensive income (loss) including noncontrolling interests	45,243	(100,545)	67,098	(66,951)
Net income attributable to noncontrolling interests	(54)	(270)	(266)	(495)
Foreign currency translation adjustments attributable to noncontrolling interests, net of tax	330	33	403	66
Comprehensive income (loss) attributable to noncontrolling interests	276	(237)	137	(429)
Comprehensive income (loss) attributable to Tetra Tech	$ 45,519	$ (100,782)	$ 67,235	$ (67,380)