Benefit Plans and Other Postretirement Benefits, Postretirement Health Care Benefits (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Other Postretirement Benefits Plan [Member]
Postretirement Health Care Benefits [Abstract]
Target pension asset allocations (as a percent)	100.00%	100.00%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	2.65%	3.47%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Pre-65	5.50%	6.00%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Post-65	5.00%	5.10%
Ultimate health care trend assumption rate (as a percent)	4.50%	4.50%
Defined Benefit Plan Period Until Ultimate Health Care Trend Rate Is Reached	5	3
Other Postretirement Benefits Plan [Member] | Domestic and international equity securities
Postretirement Health Care Benefits [Abstract]
Target pension asset allocations (as a percent)	15.00%	15.00%
Other Postretirement Benefits Plan [Member] | Long-Duration Fixed Income and Interest Rate Swap Securities [Member]
Postretirement Health Care Benefits [Abstract]
Target pension asset allocations (as a percent)	0.00%	0.00%
Other Postretirement Benefits Plan [Member] | Short-to-intermediate fixed income securities
Postretirement Health Care Benefits [Abstract]
Target pension asset allocations (as a percent)	72.00%	72.00%
Other Postretirement Benefits Plan [Member] | Alternative investments
Postretirement Health Care Benefits [Abstract]
Target pension asset allocations (as a percent)	9.00%	9.00%
Other Postretirement Benefits Plan [Member] | Cash
Postretirement Health Care Benefits [Abstract]
Target pension asset allocations (as a percent)	4.00%	4.00%
Pension Plan [Member]
Postretirement Health Care Benefits [Abstract]
Target pension asset allocations (as a percent)	100.00%	100.00%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	2.71%	3.49%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase	3.75%	3.75%
Pension Plan [Member] | Domestic and international equity securities
Postretirement Health Care Benefits [Abstract]
Target pension asset allocations (as a percent)	35.00%	37.00%
Pension Plan [Member] | Long-Duration Fixed Income and Interest Rate Swap Securities [Member]
Postretirement Health Care Benefits [Abstract]
Target pension asset allocations (as a percent)	35.00%	30.00%
Pension Plan [Member] | Short-to-intermediate fixed income securities
Postretirement Health Care Benefits [Abstract]
Target pension asset allocations (as a percent)	13.00%	14.00%
Pension Plan [Member] | Alternative investments
Postretirement Health Care Benefits [Abstract]
Target pension asset allocations (as a percent)	15.00%	17.00%
Pension Plan [Member] | Cash
Postretirement Health Care Benefits [Abstract]
Target pension asset allocations (as a percent)	2.00%	2.00%