CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 29, 2019	Jun. 30, 2018	Jun. 29, 2019	Jun. 30, 2018
Income Statement [Abstract]
Revenue	$ 260,119	$ 208,398	$ 966,663	$ 864,069
Cost of revenue	142,749	112,909	563,591	491,037
Gross profit	117,370	95,489	403,072	373,032
Operating expenses
Research and development	44,355	35,444	121,530	104,209
Sales and marketing	61,482	60,819	176,705	214,077
General and administrative	26,583	20,860	74,308	63,822
Total operating expenses	132,420	117,123	372,543	382,108
Operating income (loss)	(15,050)	(21,634)	30,529	(9,076)
Other income (expense), net
Interest income (expense), net	806	(1,116)	1,019	(3,367)
Other income (expense), net	1,068	(3,744)	(3,640)	(315)
Total other income (expense), net	1,874	(4,860)	(2,621)	(3,682)
Income (loss) before provision for income taxes	(13,176)	(26,494)	27,908	(12,758)
Provision for income taxes	833	494	3,074	1,126
Net income (loss)	(14,009)	(26,988)	24,834	(13,884)
Net income (loss) attributable to common stockholders:
Basic	(14,009)	(26,988)	24,834	(13,884)
Diluted	$ (14,009)	$ (26,988)	$ 24,834	$ (13,884)
Basic (in USD per share)	$ (0.13)	$ (0.45)	$ 0.24	$ (0.23)
Diluted (in USD per share)	$ (0.13)	$ (0.45)	$ 0.22	$ (0.23)
Weighted-average shares used in computing net loss per share attributable to common stockholders:
Basic (in shares)	105,522,313	60,074,763	102,667,316	59,484,761
Diluted (in shares)	105,522,313	60,074,763	112,542,998	59,484,761
Total comprehensive loss
Net income (loss)	$ (14,009)	$ (26,988)	$ 24,834	$ (13,884)
Change in foreign currency translation adjustment	(663)	162	506	523
Comprehensive income (loss)	$ (14,672)	$ (26,826)	$ 25,340	$ (13,361)