CONDENSED CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Treasury Stock	Accumulated Deficit	Accumulated Other Comprehensive Loss
Balance, beginning of period (in shares) at Sep. 29, 2018		100,868,250		(807,040)
Balance, beginning of period at Sep. 29, 2018	$ 208,358	$ 101	$ 424,617	$ (11,072)	$ (203,611)	$ (1,677)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock pursuant to equity incentive plans (in shares)		174,453
Issuance of common stock pursuant to equity incentive plans	462	$ 0	462
Stock-based compensation expense	9,032		9,032
Net income	61,667				61,667
Change in foreign currency translation adjustment	509					509
Balance, end of period (in shares) at Dec. 29, 2018		101,042,703		(807,040)
Balance, ending of period at Dec. 29, 2018	280,028	$ 101	434,111	$ (11,072)	(141,944)	(1,168)
Balance, beginning of period (in shares) at Sep. 28, 2019		109,623,417		(1,020,775)
Balance, beginning of period at Sep. 28, 2019	$ 280,928	$ 110	502,757	$ (13,498)	(208,377)	(64)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock pursuant to equity incentive plans (in shares)	1,136,193	1,561,696
Issuance of common stock pursuant to equity incentive plans	$ 7,969	$ 1	7,968
Purchase of treasury stock (in shares)	(227,241)			(372,149)
Purchase of treasury stock	$ (5,078)			$ (5,078)
Stock-based compensation expense	13,204		13,204
Net income	70,775				70,775
Change in foreign currency translation adjustment	(519)					(519)
Balance, end of period (in shares) at Dec. 28, 2019		111,185,113		(1,392,924)
Balance, ending of period at Dec. 28, 2019	$ 367,279	$ 111	$ 523,929	$ (18,576)	$ (137,602)	$ (583)