CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands		3 Months Ended				9 Months Ended
		Sep. 30, 2017		Sep. 30, 2016		Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Revenue		$ 112,786		$ 80,717		$ 307,066	$ 223,376
Cost of revenue	[1]	33,693		23,866		92,464	68,318
Gross profit		79,093		56,851		214,602	155,058
Operating expenses:
Research and development	[1]	29,358		22,953		84,512	66,683
Sales and marketing	[1]	56,778		43,899		156,707	119,421
General and administrative	[1]	21,398		16,212		59,502	48,149
Total operating expenses		107,534	[1]	83,064	[1]	300,721	234,253	[1]
Operating loss		(28,441)		(26,213)		(86,119)	(79,195)
Other income, net		619		681		1,345	745
Loss before provision for (benefit from) income taxes		(27,822)		(25,532)		(84,774)	(78,450)
Provision for (benefit from) income taxes		(133)		294		(786)	800
Net loss		$ (27,689)		$ (25,826)		$ (83,988)	$ (79,250)
Net loss per share, basic and diluted (usd per share)		$ (0.28)		$ (0.27)		$ (0.85)	$ (0.86)
Weighted-average shares used to compute net loss per share, basic and diluted (in shares)		100,659		94,085		99,203	92,274

[1] Includes share-based compensation expense as follows: Three Months EndedSeptember 30, Nine Months EndedSeptember 30,2017 2016 2017 2016Cost of revenue$2,408 $1,919 $6,668 $5,355Research and development7,776 7,172 22,273 20,548Sales and marketing6,716 6,657 18,362 17,780General and administrative5,619 4,247 15,502 12,654