Earnings per Share ("EPS") (Tables)

3 Months Ended

Dec. 29, 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
	December 29, 2019		December 30, 2018
	(in thousands, except per share data)
Net income attributable to Tetra Tech	$	47,310	$	41,997
Weighted-average common shares outstanding – basic	54,560		55,390
Effect of dilutive stock options and unvested restricted stock	878		976
Weighted-average common shares outstanding – diluted	55,438		56,366
Earnings per share attributable to Tetra Tech:
Basic	$	0.87	$	0.76
Diluted	$	0.85	$	0.75