CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Total
BALANCE at Dec. 31, 2013	$ 160,259	$ 2	$ 19,007	$ (128,834)	$ (109,825)
BALANCE, Shares at Dec. 31, 2013	49,446,072	11,008,283
Issuance of common stock for stock option exercises, net of repurchases			2,280		$ 2,280
Issuance of common stock for stock option exercises, net of repurchases, Shares		1,044,087			1,089,708
Vesting of early exercised stock options			669		$ 669
Vesting of early exercised stock options, Shares		1,400,259
Issuance of Series F preferred stock at $9.9550 per share—net of issuance costs	$ 1,994
Issuance of Series E or F preferred stock at $9.9550 per share - net of issuance costs (in Shares)	200,903
Stock-based compensation			16,749		16,749
Conversion of preferred stock for initial public offering	$ (162,253)	$ 5	162,248		162,253
Conversion of preferred stock for initial public offering, Shares	(49,646,975)	49,646,975
Issuance of common stock for initial public offering, net of issuance costs of $4,076		$ 1	102,874		102,875
Issuance of common stock for initial public offering, net of issuance costs of $4,076, Shares		12,777,777
Purchase of Averail Corporation			1,982		1,982
Purchase of Averail Corporation		276,463
Net loss				(61,889)	(61,889)
BALANCE at Dec. 31, 2014		$ 8	305,809	(190,723)	115,094
BALANCE, Shares at Dec. 31, 2014		76,153,844
Issuance of common stock for stock option exercises, net of repurchases			5,846		$ 5,846
Issuance of common stock for stock option exercises, net of repurchases, Shares		2,776,221			2,817,915
Vesting of early exercised stock options			246		$ 246
Vesting of early exercised stock options, Shares		198,564
Issuance of common stock pursuant to the Employee Stock Purchase Plan			7,359		7,359
Issuance of common stock pursuant to the Employee Stock Purchase Plan, Shares		1,273,147
Vesting of restricted stock units, Shares		924,461
Stock-based compensation			24,076		24,076
Net loss				(84,482)	(84,482)
BALANCE at Dec. 31, 2015		$ 8	343,336	(275,205)	68,139
BALANCE, Shares at Dec. 31, 2015		81,326,237
Issuance of common stock for stock option exercises, net of repurchases			2,468		$ 2,468
Issuance of common stock for stock option exercises, net of repurchases, Shares		1,040,902			1,040,902
Vesting of early exercised stock options			43		$ 43
Vesting of early exercised stock options, Shares		9,957
Issuance of common stock pursuant to the Employee Stock Purchase Plan			4,851		4,851
Issuance of common stock pursuant to the Employee Stock Purchase Plan, Shares		1,799,341
Issuance of common shares pursuant to the Employee Stock-Settled Bonus Plan		$ 1	5,638		5,639
Issuance of common stock shares pursuant to the Employee Stock-Settled Bonus Plan, shares		1,653,371
Vesting of restricted stock units, Shares		3,236,223
Stock-based compensation			26,857		26,857
Net loss				(67,180)	(67,180)
BALANCE at Dec. 31, 2016		$ 9	$ 383,193	$ (342,385)	$ 40,817
BALANCE, Shares at Dec. 31, 2016		89,066,031