v2.4.0.8
Share - Based Compensation - Summarizes the Activities for Unvested RSUs and DSUs (Detail) (USD $)
12 Months Ended
Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Expected to vest after December 31, 2013 5,033,649
Restricted Stock [Member]
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Unvested - Beginning balance   
Granted 45,611
Vested (10,331)
Forfeited/canceled   
Unvested - Ending balance 35,280
Expected to vest after December 31, 2013 31,850
Weighted Average Grant Date Fair Value, Granted $ 26.26
Weighted Average Grant Date Fair Value, Vested $ 24.87
Weighted Average Grant Date Fair Value, Forfeited/canceled   
Weighted Average Grant Date Fair Value, Unvested - Ending balance $ 26.67