Derivative Instruments (Gains (Losses) On Derivative Instruments Designated As Cash Flow Hedges) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Gains (losses) on derivative instruments designated and qualifying as cash flow hedges
Offset to net investment income	$ 4,990	$ 4,874	$ 4,827
Offset to realized gain (loss)	(170)	(339)	(151)
Offset to interest and debt expense	(253)	(331)	(272)
Parent Company [Member]
Gains (losses) on derivative instruments designated and qualifying as cash flow hedges
Offset to net investment income	2	3
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	22	16	14
Offset to realized gain (loss)	9	8
Offset to interest and debt expense	$ (18)	$ (10)	$ 1