Annual report pursuant to Section 13 and 15(d)

Summary of Restricted Stock Award Activity (Detail)

v3.10.0.1
Summary of Restricted Stock Award Activity (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Restricted Stock      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of restricted stock unit awards that vested during the period 250,442 192,230 430,056
Fair value of restricted shares that vested during the period $ 9,501 $ 8,172 $ 14,662
Compensation expense recognized during the period 9,655 8,384 8,250
Income tax benefit recognized upon vesting of share based awards $ 1,744 $ 2,667 $ 5,555
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 127,084 97,115 213,984
Fair value of restricted shares that vested during the period $ 4,846 $ 4,155 $ 7,260
Accumulated dividends paid upon vesting of restricted stock unit awards 526 558 662
Compensation expense recognized during the period 4,681 4,297 5,144
Income tax benefit recognized upon vesting of share based awards $ 708 $ 1,745 $ 3,049