Annual report pursuant to Section 13 and 15(d)

Summary of Restricted Stock Award Activity (Detail)

v3.6.0.2
Summary of Restricted Stock Award Activity (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Restricted Stock      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of restricted stock unit awards that vested during the period 430,056 329,437 625,843
Fair value of restricted shares that vested during the period $ 14,662 $ 14,424 $ 18,773
Income tax benefit recognized upon vesting of share based awards 5,555 3,823 5,625
Compensation expense recognized during the period $ 8,250 $ 9,600 $ 9,534
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 213,984 123,769 395,751
Fair value of restricted shares that vested during the period $ 7,260 $ 5,483 $ 11,420
Accumulated dividends paid upon vesting of restricted stock unit awards 662 442 1,352
Income tax benefit recognized upon vesting of share based awards 3,049 2,303 4,796
Compensation expense recognized during the period $ 5,144 $ 6,158 $ 3,284