Benefit Plans and Other Postretirement Benefits, Defined Contribution Plans (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Administrative Expense	$ 2,000,000	$ 2,000,000	$ 2,000,000
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
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
Net benefit cost recognized for financial reporting	$ 1,000,000	$ 1,000,000	1,000,000
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
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%
Net benefit cost recognized for financial reporting	$ 8,000,000	$ 13,000,000	$ 6,000,000
Supplemental Executive Retirement Plan (SERP) and Nonqualified Pension Plan | Parent Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Net benefit cost recognized for financial reporting	$ 4,000,000	$ 6,000,000