Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 26, 2016	Jun. 28, 2015	Jun. 26, 2016	Jun. 28, 2015
Condensed Consolidated Statements of Income
Revenue	$ 666,869	$ 575,108	$ 1,854,961	$ 1,720,927
Subcontractor costs	(168,235)	(153,209)	(456,606)	(429,194)
Other costs of revenue	(413,551)	(340,181)	(1,165,323)	(1,061,419)
Gross profit	85,083	81,718	233,032	230,314
Selling, general and administrative expenses	(44,993)	(40,997)	(124,626)	(125,695)
Acquisition and integration expenses	(1,005)		(16,916)
Contingent consideration - fair value adjustments			(2,823)	3,113
Operating income	39,085	40,721	88,667	107,732
Interest expense, net	(2,590)	(2,026)	(8,501)	(5,621)
Income before income tax expense	36,495	38,695	80,166	102,111
Income tax expense	(10,805)	(12,443)	(27,497)	(31,202)
Net income including noncontrolling interests	25,690	26,252	52,669	70,909
Net (income) loss from noncontrolling interests	4	(46)	9	(111)
Net income attributable to Tetra Tech	$ 25,694	$ 26,206	$ 52,678	$ 70,798
Earnings per share attributable to Tetra Tech:
Basic (in dollars per share)	$ 0.44	$ 0.44	$ 0.90	$ 1.16
Diluted (in dollars per share)	$ 0.44	$ 0.43	$ 0.89	$ 1.14
Weighted-average common shares outstanding:
Basic (in shares)	57,796	60,207	58,483	61,293
Diluted (in shares)	58,616	60,792	59,228	61,887
Cash dividends paid per share	$ 0.09	$ 0.08	$ 0.25	$ 0.22