Pension and Other Post-Retirement Benefit Plans (Plan Asset Allocations) (Details)	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	100.00%	100.00%
Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	1.00%	0.00%
Equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	30.00%	26.00%
Fixed income securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	69.00%	74.00%
Maximum [Member] | Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	10.00%
Maximum [Member] | Equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	35.00%
Maximum [Member] | Fixed income securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	80.00%
Maximum [Member] | US Treasury Securities [Member] | Equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	5.00%
Maximum [Member] | US Treasury Securities [Member] | Fixed income securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	10.00%
Minimum [Member] | Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	0.00%
Minimum [Member] | Equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	15.00%
Minimum [Member] | Fixed income securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocation	60.00%