Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Dec. 27, 2015	Dec. 28, 2014
Condensed Consolidated Statements of Income
Revenue	$ 560,708	$ 581,056
Subcontractor costs	(139,752)	(143,976)
Other costs of revenue	(347,796)	(358,281)
Selling, general and administrative expenses	(39,229)	(42,187)
Contingent consideration - fair value adjustments	(1,001)
Operating income	32,930	36,612
Interest expense	(1,660)	(1,790)
Income before income tax expense	31,270	34,822
Income tax expense	(8,030)	(9,176)
Net income including noncontrolling interests	23,240	25,646
Net income attributable to noncontrolling interests	(1)	(71)
Net income attributable to Tetra Tech	$ 23,239	$ 25,575
Earnings per share attributable to Tetra Tech:
Basic (in dollars per share)	$ 0.39	$ 0.41
Diluted (in dollars per share)	$ 0.39	$ 0.41
Weighted-average common shares outstanding:
Basic (in shares)	59,058	62,452
Diluted (in shares)	59,793	63,112
Cash dividends paid per share	$ 0.08	$ 0.07