Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Mar. 27, 2020	Dec. 27, 2019	Mar. 29, 2019	Dec. 28, 2018	Mar. 27, 2020	Mar. 29, 2019
Numerator:
Net income	$ 39,193	$ 34,790	$ 29,555	$ 26,949	$ 73,983	$ 56,504
Less: Undistributed earnings allocated to participating securities	853		857		1,719	1,507
Net income available to common shareholders	$ 38,340		$ 28,698		$ 72,264	$ 54,997
Denominator:
Weighted-average shares outstanding - Basic (in shares)	47,404		46,079		47,268	46,529
Effect of dilutive securities: Non-participating employee stock options (in shares)	691		1,290		961	1,288
Weighted-average shares outstanding - diluted (in shares)	48,095		47,369		48,229	47,817
Basic earnings per share (in dollars per share)	$ 0.81		$ 0.62		$ 1.53	$ 1.18
Diluted earnings per share (in dollars per share)	$ 0.80		$ 0.61		$ 1.50	$ 1.15