Stockholders' Equity - Summary of RSU Activity (Detail) (Restricted Stock Units (RSUs) [Member], USD $)
In Thousands, except Per Share data, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Restricted Stock Units (RSUs) [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Outstanding and non-vested, Beginning balance 372
Granted 980
Vested and shares issued (3)
Forfeited (14)
Outstanding and non-vested, Ending balance 1,335
Outstanding and non-vested, Beginning balance $ 22.99
Weighted average fair value at grant date $ 30.76
Vested and shares issued $ 18.25
Forfeited $ 25.00
Outstanding and non-vested, Ending balance $ 28.68