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Stock Incentive Plans - Schedule of Performance Share Unit Activity (Detail) - Performance Share Units (“PSUs”) [Member]
12 Months Ended
Dec. 31, 2020
$ / shares
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Nonvested beginning balance, Units | shares 35,826
Vested, Units | shares (13,912)
Cancelled/Forfeited, Units | shares (13,450)
Nonvested ending balance, Units | shares 8,464
Nonvested beginning balance, Weighted Average Grant Date Fair Value | $ / shares $ 67.47
Vested, Weighted Average Grant Date Fair Value | $ / shares 53.42
Cancelled/Forfeited, Weighted Average Grant Date Fair Value | $ / shares 76.15
Nonvested ending balance, Weighted Average Grant Date Fair Value | $ / shares $ 76.78