Stockholders' Equity - Summary of Stock Option Activity under the Company's Equity-Based Plans (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Beginning Balance	6,892,810
Number of Shares, Granted	277,200
Number of Shares, Exercised	(1,442,538)
Number of Shares, Forfeited	(467,002)
Number of Shares, Expired	(1,250)
Number of Shares, Ending Balance	5,259,220	6,892,810
Number of Shares, Exercisable, Ending Balance	1,830,015
Number of Shares, Vested and expected to vest, Ending Balance	5,031,744
Weighted-Average Exercise Price, Beginning Balance	$ 6.13
Weighted-Average Exercise Price, Granted	33.42
Weighted-Average Exercise Price, Exercised	3.28
Weighted-Average Exercise Price, Forfeited	8.17
Weighted-Average Exercise Price, Expired	10.98
Weighted-Average Exercise Price, Ending Balance	8.17	$ 6.13
Weighted-Average Exercise Price, Exercisable, Ending Balance	4.74
Weighted-Average Exercise Price, Vested and expected to vest, Ending Balance	$ 7.96
Weighted-Average Remaining Contractual Term (Years)	7 years 11 months 12 days	8 years 2 months 19 days
Weighted-Average Remaining Contractual Term (Years), Exercisable	7 years 4 months 21 days
Weighted-Average Remaining Contractual Term (Years), Vested and Expected to vest	7 years 11 months 1 day
Aggregate Intrinsic Value, Beginning Balance	$ 173,338
Aggregate Intrinsic Value, Ending Balance	90,346	$ 173,338
Aggregate Intrinsic Value, Exercisable, Ending Balance	37,723
Aggregate Intrinsic Value, Vested and expected to Vest, Ending Balance	$ 87,501