Investments (Composition Of Current And Past Due Mortgage Loans On Real Estate) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Mortgage Loans On Real Estate Aging [Abstract]
Current	$ 15,802		$ 13,189
30 to 59 days past due	35		9
60 to 89 days past due	10		1
Greater than 90 days past due	9
Valuation allowance	(2)
Unamortized premium (discount)	5		(9)
Total carrying value	15,859		13,190
Commercial [Member]
Mortgage Loans On Real Estate Aging [Abstract]
Current	15,112		12,959
30 to 59 days past due	25
Greater than 90 days past due	1
Valuation allowance				$ (1)	$ (2)	$ (3)
Unamortized premium (discount)	(18)		(17)
Total carrying value	15,120		12,942
Residential [Member]
Mortgage Loans On Real Estate Aging [Abstract]
Current	690		230
30 to 59 days past due	10		9
60 to 89 days past due	10		1
Greater than 90 days past due	8
Valuation allowance	(2)
Unamortized premium (discount)	23		8
Total carrying value	$ 739		$ 248