Retirement Plans - Summary of Plan's Weighted Average Asset Allocations (Detail)	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Total weighted average asset	100.00%	100.00%
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total weighted average asset	61.00%	57.00%
Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total weighted average asset	32.00%	36.00%
Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Total weighted average asset	7.00%	7.00%