Annual report pursuant to Section 13 and 15(d)

Summary of Restricted Stock Award Activity (Detail)

v3.3.1.900
Summary of Restricted Stock Award Activity (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Restricted Stock      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of restricted stock unit awards that vested during the period 329,437 625,843 522,129
Fair value of restricted shares that vested during the period $ 14,424 $ 18,773 $ 10,161
Income tax benefit recognized upon vesting of restricted stock unit awards 3,823 5,625 4,268
Compensation expense recognized during the period $ 9,600 $ 9,534 $ 12,738
Restricted Stock Units (RSUs)      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of restricted stock unit awards that vested during the period 123,769 395,751 295,751
Fair value of restricted shares that vested during the period $ 5,483 $ 11,420 $ 8,723
Accumulated dividends paid upon vesting of restricted stock unit awards 442 1,352 939
Income tax benefit recognized upon vesting of restricted stock unit awards 2,303 4,796 3,663
Compensation expense recognized during the period $ 6,158 $ 3,284 $ 4,148