Benefit Plans - Target Allocation of Assets and Acceptable Ranges (Detail) - Pension	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Target allocation of assets	100.00%
Domestic equities
Defined Benefit Plan Disclosure [Line Items]
Target allocation of assets	37.00%
Domestic equities | Minimum
Defined Benefit Plan Disclosure [Line Items]
Allowable range of assets	30.00%
Domestic equities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Allowable range of assets	41.00%
Foreign equities
Defined Benefit Plan Disclosure [Line Items]
Target allocation of assets	11.00%
Foreign equities | Minimum
Defined Benefit Plan Disclosure [Line Items]
Allowable range of assets	5.00%
Foreign equities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Allowable range of assets	13.00%
Fixed income
Defined Benefit Plan Disclosure [Line Items]
Target allocation of assets	50.00%
Fixed income | Minimum
Defined Benefit Plan Disclosure [Line Items]
Allowable range of assets	40.00%
Fixed income | Maximum
Defined Benefit Plan Disclosure [Line Items]
Allowable range of assets	65.00%
Real estate
Defined Benefit Plan Disclosure [Line Items]
Target allocation of assets	2.00%
Real estate | Minimum
Defined Benefit Plan Disclosure [Line Items]
Allowable range of assets	0.00%
Real estate | Maximum
Defined Benefit Plan Disclosure [Line Items]
Allowable range of assets	4.00%
Cash
Defined Benefit Plan Disclosure [Line Items]
Target allocation of assets	0.00%
Allowable range of assets	0.00%