Stockholders Equity - Summary of PSU Activity (Detail) (Performance Shares [Member], USD $)
In Thousands, except Per Share data, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Performance Shares [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Outstanding and non-vested, Beginning balance 0
Granted 184
Forfeited 0
Outstanding and non-vested, Ending balance 184
Outstanding and non-vested, Beginning balance $ 0
Weighted average fair value at grant date $ 30.76
Forfeited $ 0
Outstanding and non-vested, Ending balance $ 30.76