Benefit Plans and Other Postretirement Benefits, Postretirement Health Care Benefits (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Other Postretirement Benefits Plan [Member]
Postretirement Health Care Benefits [Abstract]
Discount rate for year-end valuation (as a percent)	3.09%	2.65%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Pre-65	5.30%	5.50%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Post-65	4.90%	5.00%
Ultimate health care trend assumption rate (as a percent)	4.50%	4.50%
Period until ultimate trend rate is reached (in years)	$ 4	$ 5
Total benefit obligation	$ 34,000,000	$ 38,000,000	$ 44,000,000
Target pension asset allocations (as a percent)	100.00%	100.00%
Other Postretirement Benefits Plan [Member] | 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 Long-duration fixed income and interest rate swap securities
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)	71.00%	72.00%
Other Postretirement Benefits Plan [Member] | Alternative investments
Postretirement Health Care Benefits [Abstract]
Target pension asset allocations (as a percent)	8.00%	9.00%
Other Postretirement Benefits Plan [Member] | Cash
Postretirement Health Care Benefits [Abstract]
Target pension asset allocations (as a percent)	6.00%	4.00%
Pension Plan [Member]
Postretirement Health Care Benefits [Abstract]
Discount rate for year-end valuation (as a percent)	3.08%	2.71%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase	3.75%	3.75%
Total benefit obligation	$ 545,000,000	$ 562,000,000	$ 519,000,000
Target pension asset allocations (as a percent)	100.00%	100.00%
Pension Plan [Member] | Equity securities
Postretirement Health Care Benefits [Abstract]
Target pension asset allocations (as a percent)	33.00%	35.00%
Pension Plan [Member] | Long-Duration Fixed Income and Long-duration fixed income and interest rate swap securities
Postretirement Health Care Benefits [Abstract]
Target pension asset allocations (as a percent)	37.00%	35.00%
Pension Plan [Member] | Short-to-intermediate fixed income securities
Postretirement Health Care Benefits [Abstract]
Target pension asset allocations (as a percent)	11.00%	13.00%
Pension Plan [Member] | Alternative investments
Postretirement Health Care Benefits [Abstract]
Target pension asset allocations (as a percent)	17.00%	15.00%
Pension Plan [Member] | Cash
Postretirement Health Care Benefits [Abstract]
Target pension asset allocations (as a percent)	2.00%	2.00%
Supplemental Executive Retirement Plan (SERP) and Nonqualified Pension Plan
Postretirement Health Care Benefits [Abstract]
Total benefit obligation	$ 2,000,000	$ 2,000,000