Stock-Based Compensation - Summary of Stock Option Activity (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Beginning Balance	190,160
Number of Shares, Granted	0
Number of Shares, Exercised	(3,643)
Number of Shares, Forfeited	0
Number of Shares, Ending Balance	186,517
Weighted Average Exercise Price, Beginning Balance	$ 20.11
Weighted Average Exercise Price, Granted	$ 0
Weighted Average Exercise Price, Exercised	$ 32.50
Weighted Average Exercise Price, Forfeited	$ 0
Weighted Average Exercise Price, Ending Balance	$ 19.87