Summarizes Stock Option Activity (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options outstanding, beginning balance, shares	2,129,929	2,163,825	2,132,506
Granted, shares	510,000	160,000	609,642
Exercised, shares	(672,753)	(176,896)	(571,964)
Forfeited, shares	(24,000)	(17,000)	(6,359)
Stock options outstanding, ending balance, shares	1,943,176	2,129,929	2,163,825
Stock options exercisable, shares	1,055,176	1,520,720	1,222,959
Stock options outstanding, beginning balance, weighted average exercise price	$ 8.82	$ 8.12	$ 6.34
Granted, weighted average exercise price	$ 19.64	$ 12.88	$ 12.31
Exercised, weighted average exercise price	$ 7.21	$ 4.46	$ 5.88
Forfeited, weighted average exercise price	$ 11.27	$ 4.05	$ 5.66
Stock options outstanding, ending balance, weighted average exercise price	$ 12.19	$ 8.82	$ 8.12
Stock options exercisable, weighted average exercise price	$ 12.21	$ 7.57	$ 7.23
Stock options outstanding, weighted-average remaining contractual term	6 years 11 months 27 days	6 years 11 months 27 days	6 years 8 months 27 days
Stock options outstanding, weighted-average remaining contractual term	6 years 2 months 12 days	6 years 2 months 12 days	6 years 26 days
Stock options outstanding, aggregate intrinsic value	$ 28,379	$ 5,640	$ 15,408
Stock options outstanding, aggregate intrinsic value	$ 19,314	$ 5,966	$ 9,831