Stock-Based Compensation (Details 3) - Employee stock options - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Number of Shares subject to outstanding options
Balance at the beginning of the period (in shares)	2,826,794
Options granted (in shares)	930,250	1,019,021
Options forfeited (in shares)	(9,375)
Options exercised (in shares)	(369,743)
Balance at the end of the period (in shares)	3,377,926
Weighted Average Exercise Price (Per Share)
Balance at the beginning of the period (in dollars per share)	$ 5.12
Options granted (in dollars per share)	15.96
Options forfeited (in dollars per share)	18.75
Options exercised (in dollars per share)	1.47
Balance at the end of the period (in dollars per share)	$ 8.47
Exercisable (in shares)	1,515,353
Exercisable (in dollars per share)	$ 3.69
Weighted-Average Remaining Contractual Term, Balance outstanding	7 years 2 months 16 days
Weighted-Average Remaining Contractual Term, Exercisable	5 years 1 month 24 days
Aggregate Intrinsic Value, Balance outstanding	$ 16,173
Aggregate Intrinsic Value, Exercisable	$ 12,965
Closing price of common stock (in dollars per share)	$ 12.23
Weighted average fair value of options granted (in dollars per share)	$ 10.73	$ 7.11