Summary of Stock Option Activity (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Options outstanding, shares
Beginning Balance	600	16	517
Granted	745	600	0
Exercised	(9)	(16)	(501)
Forfeited/Expired	(135)	0	0
Ending Balance	1,201	600	16
Exercisable as of December 31, 2014	141
Expected to vest as of December 31, 2014	1,060
Total	1,201
Weighted Average Exercise Price Per Share
Beginning Balance	$ 92.84	$ 20.81	$ 20.31
Granted	$ 125.46	$ 92.84	$ 0
Exercised	$ 92.84	$ 20.81	$ 20.30
Forfeited/Expired	$ 104.48	$ 0	$ 0
Ending Balance	$ 111.77	$ 92.84	$ 20.81
Exercisable as of December 31, 2014	$ 92.84
Expected to vest as of December 31, 2014	$ 114.29
Total	$ 111.77
Aggregate Intrinsic Value
Exercised	$ 653	$ 1,262	$ 51,564
Exercisable as of December 31, 2014	9,794
Expected to vest as of December 31, 2014	51,001
Total	$ 60,795
Weighted Average Remaining Contractual Term (Years)
Exercisable as of December 31, 2014	7 years 8 months 12 days
Expected to vest as of December 31, 2014	9 years 1 month 6 days
Total	9 years