Stock-Based Compensation - Details of Stock Option Activity (Detail)	6 Months Ended
	Jun. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding, Beginning Balance	1,486,351
Number of Shares, Granted	330,639
Number of Shares, Exercised	(78,981)
Number of Shares, Expired
Number of Shares, Cancelled	(6,568)
Outstanding, Ending Balance	1,731,441
Exercisable, Ending Balance	914,480