Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Apr. 02, 2017	Mar. 27, 2016	Apr. 02, 2017	Mar. 27, 2016
Condensed Consolidated Statements of Comprehensive Income
Net income including noncontrolling interests	$ 26,867	$ 3,738	$ 53,456	$ 26,978
Other comprehensive income (loss), net of tax
Foreign currency translation adjustments	9,328	26,579	(6,671)	10,105
Gain (loss) on cash flow hedge valuations	452	(597)	1,448	513
Other comprehensive income (loss), net of tax	9,780	25,982	(5,223)	10,618
Comprehensive income including noncontrolling interests	36,647	29,720	48,233	37,596
Net (income) loss attributable to noncontrolling interests	(5)	6	(32)	5
Foreign currency translation adjustments, net of tax	(5)	(4)	(188)	(13)
Comprehensive income (loss) attributable to noncontrolling interests	(10)	2	(220)	(8)
Comprehensive income attributable to Tetra Tech	$ 36,637	$ 29,722	$ 48,013	$ 37,588