Shared-Based Compensation - Reconciliation of Option Activity (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of options, Outstanding, Beginning Balance	1,233
Number of Options, Granted	98	354
Number of Options, Exercised	(65)
Number of Options, Forfeited or expired	(8)
Number of Options, Outstanding, Ending Balance	1,258
Number of Options, Options Exercisable	882
Weighted-Average Exercise Price, Outstanding, Beginning Balance	$ 10.65
Weighted-Average Exercise Price, Granted	$ 19.69
Weighted-Average Exercise Price, Exercised	$ 11.84
Weighted-Average Exercise Price, Forfeited or expired	$ 12.62
Weighted-Average Exercise Price, Outstanding, Ending Balance	$ 11.24
Weighted-Average Exercise Price, Options exercisable	$ 10.89
Weighted-Average Remaining Contractual Term, Outstanding, Ending Balance	6 years 6 months
Weighted- Average Remaining Contractual Term, Options exercisable	5 years 6 months
Aggregate Intrinsic Value, Outstanding, Ending Balance	$ 17,995
Aggregate Intrinsic Value, Options exercisable	$ 12,964