Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Total
Balance at Dec. 31, 2012	$ 119,121		$ 6,499	$ 145	$ (82,201)	$ 43,564
Balance (in shares) at Dec. 31, 2012	25,876	3,195
Increase (Decrease) in Shareholders' Equity
Issuance of common stock in connection with initial public offering, net of underwriting discounts		$ 1	80,505			80,506
Issuance of common stock in connection with initial public offering, net of underwriting discounts (in shares)		6,659
Issuance of common stock in connection with private placement			6,500			6,500
Issuance of common stock in connection with private placement (in shares)		500
Issuance of common stock in connection with follow-on offering, net of underwriting discounts			22,519			22,519
Issuance of common stock in connection with follow-on offering, net of underwriting discounts (in shares)		662
Issuance of common stock in connection with acquisition			14,069			14,069
Issuance of common stock in connection with acquisition (in shares)		428
Cost incurred with registration of common stock issued in connection with acquisition of Insightera			(226)			(226)
Costs incurred with initial public offering and follow-on offering			(4,079)			(4,079)
Conversion of preferred stock to common stock	$ (119,121)	$ 3	119,118
Conversion of preferred stock to common stock (in shares)	(25,876)	25,876
Issuance of common stock upon exercise and early exercise of stock options			4,278			4,278
Issuance of common stock upon exercise and early exercise of stock options (in shares)		1,778
Vesting of restricted stock units (in shares)		169
Withholding taxes for the net share settlement of an equity award			(124)			(124)
Withholding taxes for the net share settlement of an equity award (in shares)		(5)
Repurchase of common stock (in shares)		(12)
Vesting of early exercised options			655			655
Stock-based compensation expense			8,087			8,087
Net loss					(47,360)	(47,360)
Foreign currency translation adjustments				53		53
Balance at Dec. 31, 2013		$ 4	257,801	198	(129,561)	128,442
Balance (in shares) at Dec. 31, 2013		39,250
Increase (Decrease) in Shareholders' Equity
Costs incurred with follow-on offering			62			62
Issuance of common stock in connection with acquisition			4,756			4,756
Issuance of common stock in connection with acquisition (in shares)		141
Issuance of common stock upon exercise and early exercise of stock options			5,508			5,508
Issuance of common stock upon exercise and early exercise of stock options (in shares)		1,534
Issuance of common stock under employee stock purchase plan			6,143			6,143
Issuance of common stock under employee stock purchase plan (in shares)		422
Investment by redeemable non-controlling interests			369			369
Vesting of restricted stock units (in shares)		234
Withholding taxes for the net share settlement of an equity award			(2,641)			(2,641)
Withholding taxes for the net share settlement of an equity award (in shares)		(87)
Repurchase of common stock (in shares)		(13)
Vesting of early exercised options			279			279
Stock-based compensation expense			25,143			25,143
Net loss					(54,337)	(54,337)
Foreign currency translation adjustments				(548)		(548)
Balance at Dec. 31, 2014		$ 4	297,420	(350)	(183,898)	113,176
Balance (in shares) at Dec. 31, 2014		41,481
Increase (Decrease) in Shareholders' Equity
Issuance of common stock upon exercise and early exercise of stock options			5,999			5,999
Issuance of common stock upon exercise and early exercise of stock options (in shares)		1,292
Issuance of common stock under employee stock purchase plan			5,629			5,629
Issuance of common stock under employee stock purchase plan (in shares)		235
Investment by redeemable non-controlling interests			233			233
Vesting of restricted stock units (in shares)		633
Withholding taxes for the net share settlement of an equity award			(740)			(740)
Withholding taxes for the net share settlement of an equity award (in shares)		(27)
Repurchase of common stock (in shares)		(8)
Vesting of early exercised options			140			140
Stock-based compensation expense			40,109			40,109
Net loss			(4,063)		(67,434)	(71,497)
Foreign currency translation adjustments				76		76
Balance at Dec. 31, 2015		$ 4	$ 344,727	$ (274)	$ (251,332)	$ 93,125
Balance (in shares) at Dec. 31, 2015		43,606