Investments (Composition Of Current And Past Due Mortgage Loans On Real Estate) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Mortgage Loans On Real Estate Aging [Abstract]
Current	$ 16,279	$ 13,259
30 to 59 days past due	30	9
60 to 90 days past due	10	1
90 or more days past due	16
Valuation allowance	(2)		$ (3)	$ (2)
Unamortized premium (discount)	6	(9)
Total carrying value	16,339	13,260
Commercial [Member]
Mortgage Loans On Real Estate Aging [Abstract]
Current	15,620	13,029
30 to 59 days past due	3
Unamortized premium (discount)	(17)	(17)
Total carrying value	15,606	13,012
Residential [Member]
Mortgage Loans On Real Estate Aging [Abstract]
Current	659	230
30 to 59 days past due	27	9
60 to 90 days past due	10	1
90 or more days past due	16
Valuation allowance	(2)
Unamortized premium (discount)	23	8
Total carrying value	$ 733	$ 248