CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Treasury Stock	Accumulated Deficit	Accumulated Other Comprehensive Loss	Private placement	Private placement Common Stock	Private placement Additional Paid-In Capital	IPO	IPO Common Stock	IPO Additional Paid-In Capital
Redeemable Convertible Preferred Stock, beginning balance (in shares) at Oct. 03, 2015	32,395,828
Redeemable Convertible Preferred Stock, beginning balance at Oct. 03, 2015	$ 88,637
Increase (Decrease) in Temporary Equity [Roll Forward]
Net exercise of Series C preferred stock warrants (in shares)	86,762
Net exercise of Series C preferred stock warrants	$ 1,704
Redeemable Convertible Preferred Stock, ending balance (in shares) at Oct. 01, 2016	32,482,590
Redeemable Convertible Preferred Stock, ending balance at Oct. 01, 2016	$ 90,341
Balances, beginning of period (in shares) at Oct. 03, 2015		78,546,014		(24,982,950)
Balances, beginning of period at Oct. 03, 2015	(19,859)	$ 79	$ 333,459	$ (218,345)	$ (135,576)	$ 524
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)		1,278,150
Exercise of stock options	3,670	$ 1	3,669
Retirement of treasury stock (in shares)		(24,982,950)
Retirement of treasury stock	0	$ (25)	(218,320)
Retirement of treasury stock (in shares)				24,982,950
Retirement of treasury stock				$ 218,345
Purchase of treasury stock (in shares)				(7,780)
Purchase of treasury stock	(145)			$ (145)
Stock-based compensation expense	25,963		25,963
Net loss	(38,214)				(38,214)
Change in foreign currency translation adjustment	(203)					(203)
Balances, ending of period (in shares) at Oct. 01, 2016		54,841,214		(7,780)
Balances, ending of period at Oct. 01, 2016	$ (28,788)	$ 55	144,771	$ (145)	(173,790)	321
Redeemable Convertible Preferred Stock, ending balance (in shares) at Sep. 30, 2017	32,482,590
Redeemable Convertible Preferred Stock, ending balance at Sep. 30, 2017	$ 90,341
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)		3,756,088
Exercise of stock options	8,906	$ 3	8,903
Purchase of treasury stock (in shares)				(738,682)			(738,682)
Purchase of treasury stock	(10,016)			$ (10,016)			$ (10,000)
Issuance of common, net of issuance/offering costs (in shares)							742,034	742,034
Issuance of common, net of issuance/offering costs							$ 10,078	$ 1	$ 10,077
Stock-based compensation expense	36,550		36,550
Net loss	(14,217)				(14,217)
Change in foreign currency translation adjustment	$ (2,486)					(2,486)
Balances, ending of period (in shares) at Sep. 30, 2017	58,592,874	59,339,336		(746,462)
Balances, ending of period at Sep. 30, 2017	$ 27	$ 59	200,301	$ (10,161)	(188,007)	(2,165)
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)	(32,482,590)
Conversion of redeemable convertible preferred stock to common 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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)	2,657,436	2,657,436
Exercise of stock options	$ 9,345	$ 3	9,342
Purchase of treasury stock (in shares)				(60,578)
Purchase of treasury stock	(911)			$ (911)
Issuance of common, net of issuance/offering costs (in shares)											6,388,888
Issuance of common, net of issuance/offering costs										$ 86,027	$ 6	$ 86,021
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)		32,482,590
Conversion of redeemable convertible preferred stock to common stock upon initial public offering	90,341	$ 33	90,308
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	100,061,210	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, beginning balance at Jun. 30, 2018	$ 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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	$ (1,720)
Balances, ending of period (in shares) at Sep. 29, 2018	100,061,210	100,868,250		(807,040)
Balances, ending of period at Sep. 29, 2018	$ 208,358	$ 101	$ 424,617	$ (11,072)	$ (203,611)	$ (1,677)