Annual report pursuant to Section 13 and 15(d)

Summary of Restricted Stock Activity (Detail)

v3.10.0.1
Summary of Restricted Stock Activity (Detail) - Restricted Stock - $ / shares
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Shares of Restricted Stock      
Shares of Restricted Stock, Beginning balance 650,581 606,618 757,775
Shares of Restricted Stock, Granted 328,734 246,534 335,707
Shares of Restricted Stock, Vested (250,442) (192,230) (430,056)
Shares of Restricted Stock, Forfeited (24,520) (10,341) (56,808)
Shares of Restricted Stock, Ending balance 704,353 650,581 606,618
Weighted Average Grant Date Fair Value      
Weighted Average Grant Date Fair Value Outstanding, Beginning $ 35.81 $ 33.51 $ 30.73
Weighted Average Grant Date Fair Value, Granted 38.72 41.70 30.98
Weighted Average Grant Date Fair Value, Vested 31.27 36.26 26.60
Weighted Average Grant Date Fair Value, Forfeited 38.62 33.48 33.81
Weighted Average Grant Date Fair Value Outstanding, Ending $ 38.68 $ 35.81 $ 33.51