Condensed Financial Information (Parent Company) (Interest Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Interest Expense [Abstract]
Total interest expense	$ 647	$ 632	$ 656
Parent Company
Interest Expense [Abstract]
Total interest expense	847	833	850
Parent Company | Long-term Debt
Interest Expense [Abstract]
Total interest expense	590	570	591
Parent Company | Long-term Debt | Affiliated Entity
Interest Expense [Abstract]
Total interest expense	47	52	48
Parent Company | Secured Debt [Member]
Interest Expense [Abstract]
Total interest expense	5	6	6
Parent Company | Junior Subordinated Debt [Member]
Interest Expense [Abstract]
Total interest expense	$ 205	$ 205	$ 205