Stock- Based Compensation - Details of stock options 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, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding, Beginning Balance	1,486,351
Number of Shares, Granted	330,639
Number of Shares, Exercised	(93,845)
Number of Shares, Cancelled	(12,901)
Outstanding, Ending Balance	1,710,244
Exercisable, Ending Balance	899,616
Available For Grant	1,766,818
Weighted Average Exercise Price, Outstanding, Beginning Balance	$ 17.63
Weighted Average Exercise Price, Granted	$ 25.43
Weighted Average Exercise Price, Exercised	$ 18.24
Weighted Average Exercise Price, Cancelled	$ 18.63
Weighted Average Exercise Price, Outstanding, Ending Balance	$ 19.09
Weighted average exercise price, exercisable	$ 17.81
Aggregate Intrinsic Value, Outstanding	$ 8,941
Aggregate Intrinsic Value, Exercisable	5,619
Stock options [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted average grant-date fair value of options granted (per share)	$ 12.97	$ 7.33	$ 11.57
Aggregate intrinsic value of options exercised	877	10,256	3,515
Total fair value of shares vested	$ 3,407	$ 2,641	$ 1,655