Quarterly Financial Information-Unaudited (Tables)

12 Months Ended

Oct. 01, 2017

Quarterly Financial Information Disclosure [Abstract]

Schedule of unaudited quarterly data

	First Quarter		Second Quarter		Third Quarter		Fourth Quarter
	(in thousands, except per share data)
Fiscal Year 2017
Revenue	$	668,851	$	663,781	$	685,539	$	735,188
Operating income	39,855		42,956		45,884		54,647
Net income attributable to Tetra Tech	26,562		26,862		29,983		34,467
Earnings per share attributable to Tetra Tech (1):
Basic	$	0.47	$	0.47	$	0.52	$	0.61
Diluted	$	0.46	$	0.46	$	0.52	$	0.60
Weighted-average common shares outstanding:
Basic	57,099		57,270		57,184		56,338
Diluted	58,145		58,270		58,161		57,326
Fiscal Year 2016
Revenue	$	560,708	$	627,384	$	666,869	$	728,508
Operating income	32,930		16,650		39,085		47,190
Net income attributable to Tetra Tech	23,239		3,744		25,694		31,106
Earnings per share attributable to Tetra Tech (1):
Basic	$	0.39	$	0.06	$	0.44	$	0.54
Diluted	$	0.39	$	0.06	$	0.44	$	0.53
Weighted-average common shares outstanding:
Basic	59,058		58,451		57,796		57,309
Diluted	59,793		59,131		58,616		58,192

⁽¹⁾  The sum of the quarterly EPS may not add up to the full-year EPS due to rounding.