Stock-Based Compensation - Schedule of Standard and Market-based Stock Options Activity (Detail) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Standard Stock Options [Member]
Schedule Of Stock Options [Line Items]
Beginning outstanding balance	3,227,167	3,155,631
Granted	331,380	1,058,700
Exercised	(194,269)	(956,633)
Forfeited and cancelled	(136,182)	(30,531)
Ending outstanding balance	3,228,096	3,227,167
Aggregate intrinsic value of options exercised	$ 1,099,000	$ 5,774,000
Weighted average fair value of options granted	$ 5.53	$ 5.63
Market Condition Based Stock Options [Member]
Schedule Of Stock Options [Line Items]
Beginning outstanding balance	0
Granted	50,000
Exercised	0
Forfeited and cancelled	0
Ending outstanding balance	50,000
Aggregate intrinsic value of options exercised	$ 0
Weighted average fair value of options granted	$ 5.71