Shared-Based Compensation - Reconciliation of Option Activity (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of options, Outstanding, Beginning Balance	1,233
Number of Options, Granted	98	354
Number of Options, Exercised	(149)
Number of Options, Forfeited or expired	(8)
Number of Options, Outstanding, Ending Balance	1,174
Number of Options, Options Exercisable	819
Weighted-Average Exercise Price, Outstanding, Beginning Balance	$ 10.65
Weighted-Average Exercise Price, Granted	$ 19.69
Weighted-Average Exercise Price, Exercised	$ 10.67
Weighted-Average Exercise Price, Forfeited or expired	$ 12.62
Weighted-Average Exercise Price, Outstanding, Ending Balance	$ 11.29
Weighted-Average Exercise Price, Options exercisable	$ 10.88
Weighted-Average Remaining Contractual Term, Outstanding, Ending Balance	6 years 3 months 18 days
Weighted- Average Remaining Contractual Term, Options exercisable	5 years 2 months 12 days
Aggregate Intrinsic Value, Outstanding, Ending Balance	$ 18,065
Aggregate Intrinsic Value, Options exercisable	$ 12,965