Derivative Instruments (Gains (Losses) On Derivative Instruments Designated As Cash Flow Hedges) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Gains (losses) on derivative instruments designated and qualifying as cash flow hedges
Offset to net investment income	$ 1,251	$ 1,233
Offset to interest and debt expense	$ (71)	(91)
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		6
Offset to interest and debt expense		$ (3)