Stock-Based Compensation - Details of Stock Options Activity (Detail)	6 Months Ended
	Jun. 30, 2015 shares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Outstanding, Beginning Balance	1,765,922
Number of Shares, Granted	0
Number of Shares, Exercised	(766,813)
Number of Shares, Expired	(16,159)
Number of Shares, Canceled	(53,632)
Outstanding, Ending Balance	929,318
Exercisable, Ending Balance	600,959