CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017
Income Statement [Abstract]
Revenue	$ 208,398	$ 223,078	$ 864,069	$ 778,431
Cost of revenue	112,909	115,790	491,037	425,257
Gross profit	95,489	107,288	373,032	353,174
Operating expenses
Research and development	35,444	33,347	104,209	90,920
Sales and marketing	60,819	70,074	214,077	207,225
General and administrative	20,860	20,000	63,822	55,031
Total operating expenses	117,123	123,421	382,108	353,176
Operating loss	(21,634)	(16,133)	(9,076)	(2)
Other income (expense), net
Interest expense, net	(1,116)	(1,185)	(3,367)	(3,187)
Other income (expense), net	(3,744)	2,975	(315)	2,047
Total other income (expense), net	(4,860)	1,790	(3,682)	(1,140)
Loss before provision for (benefit from) income taxes	(26,494)	(14,343)	(12,758)	(1,142)
Provision for (benefit from) income taxes	494	196	1,126	(1,830)
Net income (loss)	(26,988)	(14,539)	(13,884)	688
Net loss attributable to common stockholders	$ (26,988)	$ (14,539)	$ (13,884)	$ 0
Net loss per share attributable to common stockholders:
Basic and diluted (in USD per share)	$ (0.45)	$ (0.26)	$ (0.23)	$ 0.00
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 and diluted (in shares)	60,074,763	56,334,641	59,484,761	55,776,325
Total comprehensive loss
Net income (loss)	$ (26,988)	$ (14,539)	$ (13,884)	$ 688
Change in foreign currency translation adjustment, net of tax	162	(406)	523	(2,295)
Comprehensive loss	$ (26,826)	$ (14,945)	$ (13,361)	$ (1,607)