Stock‑Based Compensation - Stock Options (Details) - Employee and non-employee stock options $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2016 USD ($) $ / shares shares
Stock Based Compensation
Shares available for grant, beginning balance	3,734
Additional shares authorized	2,014
Options granted (in shares)	(1,900)
Options forfeited (in shares)	534
Shares available for grant, end balance	4,382
Number of shares
Outstanding, beginning balance (in shares)	9,324
Options granted (in shares)	1,900
Options exercised (in shares)	(1,279)
Options forfeited (in shares)	(534)
Outstanding, end balance (in shares)	9,411
Exercisable (in shares)	4,888
Vested and expected to vest (in shares)	8,867
Weighted-Average Exercise Price
Outstanding, beginning balance (in dollars per share) | $ / shares	$ 3.96
Granted (in dollars per share) | $ / shares	9.74
Exercised (in dollars per share) | $ / shares	1.77
Forfeited (in dollars per share) | $ / shares	6.81
Outstanding, end balance (in dollars per share) | $ / shares	5.26
Exercisable (in dollars per share) | $ / shares	2.42
Vested and expected to vest (in dollars per share) | $ / shares	$ 5.04
Additional disclosures
Weighted average contractual term, options outstanding	7 years 10 months 6 days
Exercisable (in years)	6 years 8 months 27 days
Vested and expected to vest (in years)	7 years 9 months 7 days
Aggregate intrinsic value, options outstanding | $	$ 65,247
Aggregate intrinsic value, options exercisable | $	47,348
Aggregate intrinsic value, vested and expected to vest | $	$ 63,382