Share-based Compensation - Summary of Option Activity under the Various Plan (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Total Number of Options, Outstanding Beginning Balance	15,980
Total Number of Options, Granted	3,622
Total Number of Options, Assumed - Transaction	2,426
Total Number of Options, Exercised	(161)
Total Number of Options, Forfeited	(539)
Total Number of Options, Outstanding Ending Balance	21,328
Total Number of Options, Exercisable	971
Total Number of Options, Vested or expected to vest	18,492
Weighted Average Exercise Price, Outstanding Beginning Balance	$ 6.35
Weighted Average Exercise Price, Granted	$ 27.28
Weighted Average Exercise Price, Assumed - Transaction	$ 20.71
Weighted Average Exercise Price, Exercised	$ 3.82
Weighted Average Exercise Price, Forfeited	$ 11.90
Weighted Average Exercise Price, Outstanding Ending Balance	$ 11.42
Weighted Average Exercise Price, Exercisable	$ 20.22
Weighted Average Exercise Price, Vested or expected to vest	$ 11.60
Aggregate Intrinsic Value, Outstanding	$ 590,066
Aggregate Intrinsic Value, Exercisable	18,673
Aggregate Intrinsic Value, Vested or expected to vest	$ 508,374
Average Remaining Contractual Term, Outstanding	7 years 1 month 6 days
Average Remaining Contractual Term, Exercisable	5 years 6 months
Average Remaining Contractual Term, Vested or expected to vest	7 years 1 month 6 days