Derivative Instruments (Non Hedging Derivatives and Embedded Derivatives Effect on Income Statement) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	$ 81	$ 12	$ (204)	$ 20
Policy acquisition costs and other insurance expenses	(290)	(260)	(538)	(572)
Interest credited	187	158	333	291
Other revenues	90	107	166	201
Gain Loss On Investments Related To Change In Fair Value Of Derivatives Excluding Embedded Derivatives	(23)	14	100	3
Not Designated as Hedging Instrument
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	78	(7)	(151)	1
Not Designated as Hedging Instrument | Interest Rate Swap [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	3	34	109	58
Not Designated as Hedging Instrument | Financial Futures
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	(48)	(8)	(4)	(30)
Not Designated as Hedging Instrument | Currency Swap [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	3	(6)	(10)	(5)
Not Designated as Hedging Instrument | Foreign Currency Forwards
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	1	0	(2)	0
Not Designated as Hedging Instrument | Consumer Price Index Swap [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	26	(7)	(14)	(16)
Not Designated as Hedging Instrument | Credit Default Swaps
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	17	5	(7)	20
Not Designated as Hedging Instrument | Equity Options
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	(25)	(5)	28	(28)
Not Designated as Hedging Instrument | Longevity Swap [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Other revenues	0	2	0	4
Not Designated as Hedging Instrument | Mortality Swap [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Other revenues	0	(1)	0	0
Not Designated as Hedging Instrument | Embedded Derivatives In Modified Coinsurance Or Funds Withheld Arrangements
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	1	5	(229)	3
Not Designated as Hedging Instrument | Embedded Derivatives In Indexed Annuity [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Interest credited	(7)	8	(1)	5
Not Designated as Hedging Instrument | Embedded Derivatives In Variable Annuity [Member]
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	$ 107	$ (18)	$ (21)	$ 0