Derivative Instruments (Gains (Losses) On Derivative Instruments Designated As Cash Flow Hedges) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Gains (losses) on derivative instruments designated and qualifying as cash flow hedges
Offset to net investment income	$ 1,235	$ 1,271	$ 3,842	$ 3,736
Offset to interest and debt expense	$ (113)	(69)	$ (254)	(228)
Designated as Hedging Instrument [Member] | Cash Flow Hedges [Member] | Other Comprehensive Income (Loss) [Member]
Gains (losses) on derivative instruments designated and qualifying as cash flow hedges
Offset to net investment income		8		21
Offset to interest and debt expense		$ (4)		$ (6)