Employee Benefit Plans - Weighted Average Asset Allocations by Asset Category (Detail)	Dec. 31, 2019	Dec. 31, 2018
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Actual Asset Allocation as of December 31 (percentage)	100.00%	100.00%
Target Asset (percentage)	100.00%
Equity securities
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Actual Asset Allocation as of December 31 (percentage)	34.00%	32.00%
Target Asset (percentage)	32.00%
Debt securities
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Actual Asset Allocation as of December 31 (percentage)	43.00%	51.00%
Target Asset (percentage)	49.00%
Insurance (annuity) contracts
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Actual Asset Allocation as of December 31 (percentage)	12.00%	12.00%
Target Asset (percentage)	12.00%
Real estate
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Actual Asset Allocation as of December 31 (percentage)	10.00%	3.00%
Target Asset (percentage)	4.00%
Other
Schedule of Defined Benefit Plan Asset Allocation Targets [Line Items]
Actual Asset Allocation as of December 31 (percentage)	1.00%	2.00%
Target Asset (percentage)	3.00%