Share-Based Compensation - Stock Options Activity (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Outstanding at beginning of period, Number of Shares	2,233,460
Options granted, Number of Shares	884,703
Options exercised, Number of Shares	(305,005)
Options canceled or expired, Number of Shares	(75,501)
Outstanding at end of period, Number of Shares	2,737,657	2,233,460
Vested or expected to vest at end of period, Number of Shares	2,737,657
Exercisable at end of period, Number of Shares	1,485,918
Outstanding at beginning of period, Weighted-Average Exercise Price	$ 9.20
Options granted, Weighted-Average Exercise Price	21.00
Options exercised, Weighted-Average Exercise Price	2.14
Options canceled or expired, Weighted-Average Exercise Price	12.33
Outstanding at end of period, Weighted-Average Exercise Price	13.72	$ 9.20
Vested or expected to vest at end of period, Weighted-Average Exercise Price	13.72
Exercisable at end of period, Weighted-Average Exercise Price	$ 8.75
Outstanding at end of period, Aggregate Intrinsic Value	$ 109,778,658
Exercisable at end of period, Aggregate Intrinsic Value	$ 66,920,372
Options granted, Weighted-Average Contractual Life	9 years 1 month 6 days
Options exercised, Weighted-Average Contractual Life	2 years 2 months 12 days
Options canceled or expired, Weighted-Average Contractual Life	8 years
Outstanding at end of period, Weighted-Average Contractual Life	7 years 7 months 6 days	7 years 3 months 18 days
Exercisable at end of period, Weighted-Average Contractual Life	6 years 8 months 12 days