XML 90 R76.htm IDEA: XBRL DOCUMENT v3.20.4
Stock Plans - Summary of Performance Stock Unit Activity (Detail) - Performance Stock Unit Activity - $ / shares
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]      
Unvested Shares, Beginning Balance 238,035 218,886 242,186
Granted, Shares 67,479 83,819 62,775
Vested, Shares (132,036) (139,478) (41,660)
Performance adjustments, Shares 33,499 76,960 (35,756)
Forfeited, Shares (6,765) (2,152) (8,659)
Unvested Shares, Ending Balance 200,212 238,035 218,886
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]      
Unvested Weighted Average Grant Date Fair Value, Beginning Balance (dollars per share) $ 85.39 $ 68.43 $ 55.06
Granted, Weighted Average Grant Date Fair Value (dollars per share) 127.48 101.03 84.79
Vested, Weighted Average Grant Date Fair Value (dollars per share) 73.00 44.75 40.23
Performance adjustments, Weighted Average Grant Date Fair value (dollars per share) 72.36 44.24 45.21
Forfeited, Weighted Average Grant Date Fair Value (dollars per share) 111.60 99.82 44.53
Unvested Weighted Average Grant Date Fair Value, Ending Balance (dollars per share) $ 104.69 $ 85.39 $ 68.43