Annual report pursuant to Section 13 and 15(d)

Share-based Compensation - Schedule of Restricted Stock Awards under 2013 Plan (Detail)

v3.20.4
Share-based Compensation - Schedule of Restricted Stock Awards under 2013 Plan (Detail) - 2007 and 2013 Plan - Restricted stock awards - $ / shares
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]      
Number of Shares, Restricted stock at beginning of period 296,201 304,595 317,783
Number of Shares, Restricted stock granted 125,896 181,204 156,771
Number of Shares, Restricted stock vested (137,892) (99,527) (106,674)
Number of Shares, Restricted stock forfeited (40,497) (90,071) (63,285)
Number of Shares, Restricted stock at end of period 243,708 296,201 304,595
Weighted-Average Grant Date Fair Value Per Share, Restricted stock at beginning of period (in USD per share) $ 22.91 $ 21.98 $ 21.09
Weighted-Average Grant Date Fair Value Per Share, Restricted stock granted (in USD per share) 8.51 22.05 25.02
Weighted-Average Grant Date Fair Value Per Share, Restricted stock vested (in USD per share) 24.68 27.56 27.11
Weighted-Average Grant Date Fair Value Per Share, Restricted stock forfeited (in USD per share) 16.55 13.78 15.38
Weighted-Average Grant Date Fair Value Per Share, Restricted stock at end of period (in USD per share) $ 15.60 $ 22.91 $ 21.98