Earnings per Share ("EPS") (Tables)

9 Months Ended

Jun. 30, 2019

Earnings Per Share [Abstract]

Schedule of number of weighted-average shares used to compute basic and diluted EPS

The following table presents the number of weighted-average shares used to compute basic and diluted EPS:

	Three Months Ended				Nine Months Ended
	June 30, 2019		July 1, 2018		June 30, 2019		July 1, 2018
	(in thousands, except per share data)
Net income attributable to Tetra Tech	$	49,233	$	33,322	$	147,141	$	108,082
Weighted-average common shares outstanding – basic	54,819		55,537		55,101		55,780
Effect of dilutive stock options and unvested restricted stock	949		853		933		901
Weighted-average common shares outstanding – diluted	55,768		56,390		56,034		56,681
Earnings per share attributable to Tetra Tech:
Basic	$	0.90	$	0.60	$	2.67	$	1.94
Diluted	$	0.88	$	0.59	$	2.63	$	1.91