CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Income Statement [Abstract]
Revenue	$ 249,310	$ 260,119	$ 986,491	$ 966,663
Cost of revenue	139,519	142,749	576,071	563,591
Gross profit	109,791	117,370	410,420	403,072
Operating expenses
Research and development	57,770	44,355	159,890	121,530
Sales and marketing	77,273	61,482	205,201	176,705
General and administrative	31,662	26,583	87,989	74,308
Total operating expenses	166,705	132,420	453,080	372,543
Operating income (loss)	(56,914)	(15,050)	(42,660)	30,529
Other income (expense), net
Interest income	81	1,432	1,954	2,933
Interest expense	(360)	(626)	(1,187)	(1,914)
Other income (expense), net	365	1,068	3,366	(3,640)
Total other income (expense), net	86	1,874	4,133	(2,621)
Income (loss) before provision for (benefit from) income taxes	(56,828)	(13,176)	(38,527)	27,908
Provision for (benefit from) income taxes	152	833	(1)	3,074
Net income (loss)	(56,980)	(14,009)	(38,526)	24,834
Net income (loss) attributable to common stockholders:
Basic	(56,980)	(14,009)	(38,526)	24,834
Diluted	$ (56,980)	$ (14,009)	$ (38,526)	$ 24,834
Basic (in USD per share)	$ (0.52)	$ (0.13)	$ (0.35)	$ 0.24
Diluted (in USD per share)	$ (0.52)	$ (0.13)	$ (0.35)	$ 0.22
Weighted-average shares used in computing net loss per share attributable to common stockholders:
Basic (in shares)	109,477,622	105,522,313	109,325,785	102,667,316
Diluted (in shares)	109,477,622	105,522,313	109,325,785	112,542,998
Total comprehensive loss
Net income (loss)	$ (56,980)	$ (14,009)	$ (38,526)	$ 24,834
Change in foreign currency translation adjustment	219	(663)	(731)	506
Comprehensive income (loss)	$ (56,761)	$ (14,672)	$ (39,257)	$ 25,340