CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 30, 2019	Mar. 31, 2018	Mar. 30, 2019	Mar. 31, 2018
Income Statement [Abstract]
Revenue	$ 210,173	$ 186,720	$ 706,544	$ 655,670
Cost of revenue	119,760	105,379	420,842	378,128
Gross profit	90,413	81,341	285,702	277,542
Operating expenses
Research and development	40,080	35,237	77,175	68,766
Sales and marketing	49,371	59,233	115,223	153,258
General and administrative	23,900	20,585	47,724	42,959
Total operating expenses	113,351	115,055	240,122	264,983
Operating income (loss)	(22,938)	(33,714)	45,580	12,559
Other income (expense), net
Interest expense, net	611	(1,085)	213	(2,250)
Other income (expense), net	(710)	2,808	(4,708)	3,429
Total other income (expense), net	(99)	1,723	(4,495)	1,179
Income (loss) before provision for (benefit from) income taxes	(23,037)	(31,991)	41,085	13,738
Provision for (benefit from) income taxes	(213)	601	2,242	633
Net income (loss)	(22,824)	(32,592)	38,843	13,105
Net income (loss) attributable to common stockholders - basic	(22,824)	(32,592)	38,843	3,753
Net income (loss) attributable to common stockholders - diluted	$ (22,824)	$ (32,592)	$ 38,843	$ 4,028
Net loss per share attributable to common stockholders:
Basic (in USD per share)	$ (0.22)	$ (0.55)	$ 0.38	$ 0.06
Diluted (in USD per share)	$ (0.22)	$ (0.55)	$ 0.35	$ 0.05
Weighted-average shares used in computing net loss per share attributable to common stockholders:
Weighted-average shares used in computing net loss per share attributable to common stockholders - basic (in shares)	102,331,529	59,606,879	101,239,817	59,189,760
Weighted-average shares used in computing net loss per share attributable to common stockholders - diluted (in shares)	102,331,529	59,606,879	111,474,057	73,365,673
Total comprehensive loss
Net income (loss)	$ (22,824)	$ (32,592)	$ 38,843	$ 13,105
Change in foreign currency translation adjustment, net of tax	660	(17)	1,169	362
Comprehensive loss	$ (22,164)	$ (32,609)	$ 40,012	$ 13,467