Derivative Instruments (Gains (Losses) On Derivative Instruments Designated As Cash Flow Hedges) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Gains (losses) on derivative instruments designated and qualifying as cash flow hedges
Offset to net investment income	$ 5,223	$ 5,085	$ 4,990
Offset to realized gain (loss)	(610)	141	(170)
Offset to interest and debt expense	$ (326)	(297)	(253)
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		4	22
Offset to realized gain (loss)		27	9
Offset to interest and debt expense		$ (7)	$ (18)