Retirement Plans, Asset Allocation for Pension Plan Table (Details) - RAP	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Total	100.00%	100.00%
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Total	53.00%	51.00%
Fixed-income securities
Defined Benefit Plan Disclosure [Line Items]
Total	33.00%	33.00%
Group annuity contracts
Defined Benefit Plan Disclosure [Line Items]
Total	11.00%	11.00%
Alternative securities
Defined Benefit Plan Disclosure [Line Items]
Total	1.00%	3.00%
Other
Defined Benefit Plan Disclosure [Line Items]
Total	2.00%	2.00%