Retirement Plans (Asset Allocation Policy Ranges) (Details)	Dec. 31, 2020
Equity funds | Minimum
Defined Benefit Plan Disclosure [Line Items]
Asset allocation policy range	48.00%
Equity funds | Maximum
Defined Benefit Plan Disclosure [Line Items]
Asset allocation policy range	68.00%
Fixed income | Minimum
Defined Benefit Plan Disclosure [Line Items]
Asset allocation policy range	20.00%
Fixed income | Maximum
Defined Benefit Plan Disclosure [Line Items]
Asset allocation policy range	48.00%
Cash | Minimum
Defined Benefit Plan Disclosure [Line Items]
Asset allocation policy range	0.00%
Cash | Maximum
Defined Benefit Plan Disclosure [Line Items]
Asset allocation policy range	5.00%
Other asset classes | Minimum
Defined Benefit Plan Disclosure [Line Items]
Asset allocation policy range	0.00%
Other asset classes | Maximum
Defined Benefit Plan Disclosure [Line Items]
Asset allocation policy range	16.00%