Changes in Non-Vested TSR Awards (Detail) (TSR, USD $)
12 Months Ended
Dec. 31, 2013
TSR
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Granted, Shares 354,517
Vested, Shares   
Forfeited, Shares (14,351)
Non-vested, end of period, Shares 340,166
Granted, Weighted Average Grant Date Fair Value $ 15.91
Vested, Weighted Average Grant Date Fair Value   
Forfeited, Weighted Average Grant Date Fair Value $ 15.91
Non-vested, end of period, Weighted Average Grant Date Fair Value $ 15.91