Annual report pursuant to Section 13 and 15(d)

Summary of Restricted Stock Activity (Detail)

v3.3.1.900
Summary of Restricted Stock Activity (Detail) - Restricted Stock - $ / shares
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Shares of Restricted Stock      
Shares of Restricted Stock, Beginning balance 878,897 1,260,913 1,534,163
Shares of Restricted Stock, Granted 226,212 269,774 271,532
Shares of Restricted Stock, Vested (329,437) (625,843) (522,129)
Shares of Restricted Stock, Forfeited (17,897) (25,947) (22,653)
Shares of Restricted Stock, Ending balance 757,775 878,897 1,260,913
Weighted Average Grant Date Fair Value      
Weighted Average Grant Date Fair Value Outstanding, Beginning $ 24.92 $ 21.86 $ 18.85
Weighted Average Grant Date Fair Value, Granted 42.79 28.93 30.09
Weighted Average Grant Date Fair Value, Vested 23.72 20.53 17.27
Weighted Average Grant Date Fair Value, Forfeited 27.58 22.94 22.92
Weighted Average Grant Date Fair Value Outstanding, Ending $ 30.73 $ 24.92 $ 21.86