Shared-Based Compensation - Reconciliation of Option Activity (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of options, Outstanding, Beginning Balance		1,175
Number of Options, Granted		55	98
Number of Options, Exercised		(160)
Number of Options, Forfeited or expired		(3)
Number of Options, Outstanding, Ending Balance		1,067
Number of Options, Options Exercisable		857
Weighted-Average Exercise Price, Outstanding, Beginning Balance		$ 11.40
Weighted-Average Exercise Price, Granted		25.16
Weighted-Average Exercise Price, Exercised		11.49
Weighted-Average Exercise Price, Forfeited or expired		13.12
Weighted-Average Exercise Price, Outstanding, Ending Balance		12.08
Weighted-Average Exercise Price, Options exercisable		$ 10.91
Weighted-Average Remaining Contractual Term, Outstanding, Ending Balance		6 years 3 months 18 days
Weighted- Average Remaining Contractual Term, Options exercisable		5 years 8 months 12 days
Aggregate Intrinsic Value, Outstanding, Ending Balance	[1]	$ 14,341
Aggregate Intrinsic Value, Options exercisable	[1]	$ 12,516

[1] The intrinsic value is the amount by which the market price of our stock was greater than the exercise price of any individual option grant at June 30, 2015.