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	$ 4,962	$ 4,844	$ 4,760
Offset to realized gain (loss)	$ (828)	(92)	(456)
Qualifying Hedges [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