Schedule II-Condensed Financial Information Of Registrant (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Future Minimum Payments, Due 2020	$ 172
Future Minimum Payments, Due 2021	149
Future Minimum Payments, Due 2022	136
Future Minimum Payments, Due 2023	116
Future Minimum Payments, Due 2024	87
Future Minimum Payments, Due Thereafter	135
Total lease liabilities	640
Operating Lease, Cost	198
Parent Company [Member]
Cash dividends received from subsidiaries	3,790	$ 3,606	$ 2,268
Cash dividends paid to subsidiaries	38	36	32
Capital contribution to subsidiaries	232	4,379	$ 124
Amounts due from subsidiaries	602	$ 170
Parental Guarantees	569
Future Minimum Payments, Due 2020	11
Future Minimum Payments, Due 2021	11
Future Minimum Payments, Due 2022	11
Future Minimum Payments, Due 2023	12
Future Minimum Payments, Due 2024	11
Future Minimum Payments, Due Thereafter	70
Operating Lease, Right-of-Use Asset	99
Total lease liabilities	83
Operating Lease, Cost	$ 7