CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands		3 Months Ended				6 Months Ended
		Jun. 30, 2017		Jun. 30, 2016		Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Revenue		$ 101,273		$ 74,200		$ 194,280	$ 142,659
Cost of revenue	[1]	30,663		22,936		58,770	44,452
Gross profit		70,610		51,264		135,510	98,207
Operating expenses:
Research and development	[1]	28,698		22,134		55,154	43,731
Sales and marketing	[1]	52,628		39,350		99,929	75,522
General and administrative	[1]	19,788		16,076		38,105	31,937
Total operating expenses		101,114	[1]	77,560	[1]	193,188	151,190	[1]
Operating loss		(30,504)		(26,296)		(57,678)	(52,983)
Other income, net		508		134		726	64
Loss before provision for (benefit from) income taxes		(29,996)		(26,162)		(56,952)	(52,919)
Provision for (benefit from) income taxes		(690)		92		(652)	506
Net loss		$ (29,306)		$ (26,254)		$ (56,300)	$ (53,425)
Net loss per share, basic and diluted (usd per share)		$ (0.29)		$ (0.28)		$ (0.57)	$ (0.58)
Weighted-average shares used to compute net loss per share, basic and diluted (in shares)		99,506		92,174		98,545	91,351

[1] Includes share-based compensation expense as follows: Three Months EndedJune 30, Six Months EndedJune 30,2017 2016 2017 2016Cost of revenue$2,156 $1,802 $4,260 $3,435Research and development7,584 6,749 14,497 13,376Sales and marketing6,013 5,684 11,646 11,123General and administrative5,321 4,410 9,884 8,407