Share-based Compensation - Share-based Compensation Plan - Option Activity (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options Exercised	(69,244)
Amended and Restated 2012 Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, Outstanding beginning balance	1,973,500
Options, granted	720,500	1,978,000
Options Exercised	(69,244)
Options, canceled	(12,676)
Options, Outstanding ending balance	2,612,080	1,973,500
Options, Vested and expected to vest ending balance	2,535,376
Options Vested Outstanding Number	1,000,307
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted Average Exercise Price, Outstanding beginning balance	$ 7.50
Weighted Average Exercise Price, Granted	$ 28.02
Weighted Average Exercise Price, Exercised	$ 7.23
Weighted Average Exercise Price, Canceled	$ 15.97
Weighted Average Exercise Price, Outstanding ending balance	$ 13.13	$ 7.50
Weighted Average Exercise Price, Vested and expected to vest ending balance	$ 13.00
Weighted Average Exercise Price, Options Vested	$ 7.35
Weighted Average Remaining Contractual Life (Years), Outstanding ending balance	8 years 5 months 12 days	9 years 2 months 1 day
Weighted Average Remaining Contractual Life (Years), Vested and expected to vest ending balance	8 years 5 months 9 days
Weighted Average Remaining Contractual Term, Vested Outstanding	8 years 1 month 24 days
Aggregate Intrinsic Value, Outstanding ending balance	$ 25,298	$ 37,528
Aggregate Intrinsic Value, Vested and expected to vest ending balance	24,788
Aggregate Intrinsic Value, Options Vested	$ 13,448