Share-Based Compensation Plans - Share-Based Compensation Amounts Included in Net Income (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation expense	$ 5,945	$ 4,829	$ 4,279
Less: tax benefit	(1,535)	(1,254)	(1,117)
Share-Based Compensation amounts included in net income	4,410	3,575	3,162
Share-based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount	4,100
SICP Awards to Non-employee directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation expense	782	733	620
SICP Awards to Key Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Nonvested	28,800	20,200	15,100
Total compensation expense	$ 5,163	$ 4,096	$ 3,659

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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