Stock‑Based Compensation (Options) (Details) - Employee and non-employee stock options - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock Based Compensation
Shares available for grant, beginning balance	294
Additional shares authorized	4,985
Options granted (in shares)	(2,181)
Options forfeited (in shares)	645
Shares available for grant, end balance	3,743	294
Number of shares
Outstanding, beginning balance (in shares)	8,463
Options granted (in shares)	2,181
Options exercised (in shares)	(683)
Options forfeited (in shares)	(645)
Outstanding, end balance (in shares)	9,316	8,463
Exercisable (in shares)	5,602
Vested and expected to vest (in shares)	8,414
Weighted-Average Exercise Price
Outstanding, beginning balance (in dollars per shares)	$ 2.28
Granted (in dollars per share)	10.16
Exercised (in dollars per share)	1.72
Forfeited (in dollars per share)	5.25
Outstanding, end balance (in dollars per shares)	3.96	$ 2.28
Exercisable (in dollars per share)	1.90
Vested and expected to vest (in dollars per share)	$ 3.72
Additional disclosures
Weighted average contractual term, options outstanding	8 years 3 months 22 days	8 years 9 months 29 days
Exercisable (in years)	5 years 3 months 22 days
Vested and expected to vest (in years)	7 years 3 months 26 days
Aggregate intrinsic value, options outstanding	$ 63,713	$ 43,659
Aggregate intrinsic value, options exercisable	49,880
Aggregate intrinsic value, vested and expected to vest	59,529
Aggregate intrinsic value, options exercised	6,900	1,200	$ 700
Fair value, options vested	$ 4,500	$ 4,100	$ 1,000
Weighted-average grant date fair value, options granted	$ 7.29	$ 3.28	$ 0.99