Annual report pursuant to Section 13 and 15(d)

Summary of Restricted Stock Award Activity (Detail)

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Summary of Restricted Stock Award Activity (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Restricted Stock      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of restricted stock unit awards that vested during the period 209,821 250,442 192,230
Compensation expense recognized during the period $ 10,185 $ 9,655 $ 8,384
Fair value of restricted shares that vested during the period 8,024 9,501 8,172
Income tax deduction and benefit recognized upon vesting of restricted stock and restricted stock unit awards $ 1,516 $ 1,744 $ 2,667
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 90,895 127,084 97,115
Accumulated dividends paid upon vesting of restricted stock unit awards $ 386 $ 526 $ 558
Compensation expense recognized during the period 4,430 4,681 4,297
Fair value of restricted shares that vested during the period 3,658 4,846 4,155
Income tax deduction and benefit recognized upon vesting of restricted stock and restricted stock unit awards $ 397 $ 708 $ 1,745