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
Redeemable Convertible Preferred Stock, beginning balance (in shares) at Sep. 30, 2017	32,482,590
Redeemable Convertible Preferred Stock, beginning balance at Sep. 30, 2017	$ 90,341
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of redeemable convertible preferred stock upon initial public offering (in shares)	(32,482,590)
Conversion of redeemable convertible preferred stock upon initial public offering	$ (90,341)
Redeemable Convertible Preferred Stock, ending balance (in shares) at Sep. 29, 2018	0
Redeemable Convertible Preferred Stock, ending balance at Sep. 29, 2018	$ 0
Balances, beginning of period (in shares) at Sep. 30, 2017		59,339,336		(746,462)
Balances, beginning of period at Sep. 30, 2017	27	$ 59	$ 200,301	$ (10,161)	$ (188,007)	$ (2,165)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued, net of issuance costs (in shares)		6,388,888
Common stock issued, net of issuance costs	86,027	$ 6	86,021
Conversion of redeemable convertible preferred stock upon initial public offering (in shares)		32,482,590
Conversion of redeemable convertible preferred stock upon initial public offering	90,341	$ 33	90,308
Issuance of common stock pursuant to equity incentive plans (in shares)		2,657,436
Issuance of common stock pursuant to equity incentive plans	9,345	$ 3	9,342
Repurchase of treasury stock (in shares)				(60,578)
Repurchase of common stock	(911)			$ (911)
Stock-based compensation expense	38,645		38,645
Net loss	(15,604)				(15,604)
Change in foreign currency translation adjustment	488					488
Balances, ending of period (in shares) at Sep. 29, 2018		100,868,250		(807,040)
Balances, ending of period at Sep. 29, 2018	$ 208,358	$ 101	424,617	$ (11,072)	(203,611)	(1,677)
Redeemable Convertible Preferred Stock, ending balance (in shares) at Sep. 28, 2019	0
Redeemable Convertible Preferred Stock, ending balance at Sep. 28, 2019	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock pursuant to equity incentive plans (in shares)		8,755,167
Issuance of common stock pursuant to equity incentive plans	31,574	$ 9	31,565
Repurchase of treasury stock (in shares)				(213,735)
Repurchase of common stock	(2,426)			$ (2,426)
Stock-based compensation expense	46,575		46,575
Net loss	(4,766)				(4,766)
Change in foreign currency translation adjustment	$ 1,613					1,613
Balances, ending of period (in shares) at Sep. 28, 2019	108,602,642	109,623,417		(1,020,775)
Balances, ending of period at Sep. 28, 2019	$ 280,928	$ 110	502,757	$ (13,498)	(208,377)	(64)
Redeemable Convertible Preferred Stock, ending balance (in shares) at Oct. 03, 2020	0
Redeemable Convertible Preferred Stock, ending balance at Oct. 03, 2020	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock pursuant to equity incentive plans (in shares)		8,392,371
Issuance of common stock pursuant to equity incentive plans	42,286	$ 8	42,278
Retirement of treasury stock (in shares)		(4,100,555)		4,100,555
Retirement of treasury stock	$ 0	$ (4)	(53,652)	$ 53,656
Repurchase of treasury stock (in shares)	(3,787,783)			(3,787,783)
Repurchase of common stock	$ (50,015)			$ (50,015)
Repurchase of common stock related to equity awards (in shares)				863,135
Repurchase of common stock related to shares withheld for tax in connection with vesting of restricted stock unit awards ("RSUs")	11,029			$ 11,029
Stock-based compensation expense	57,610		57,610
Net loss	(20,115)				(20,115)
Change in foreign currency translation adjustment	$ (1,826)					(1,826)
Balances, ending of period (in shares) at Oct. 03, 2020	112,344,095	113,915,233		(1,571,138)
Balances, ending of period at Oct. 03, 2020	$ 297,839	$ 114	$ 548,993	$ (20,886)	$ (228,492)	$ (1,890)