Derivatives (Primary Risks Managed by Derivatives) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$ 101,013	$ 113,472
Derivative Asset, Fair Value, Gross Asset	6,473	3,238
Derivative Liability, Fair Value, Gross Liability	7,900	6,785
Embedded Derivative, Fair Value of Embedded Derivative Asset	323	217
Embedded Derivative, Fair Value of Embedded Derivative Liability	5,649	4,248
Derivatives Designated as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,171	3,185
Derivative Asset, Fair Value, Gross Asset	593	212
Derivative Liability, Fair Value, Gross Liability	1	27
Derivatives Designated as Hedging Instruments: | Cash flow hedges: | Interest rate forwards
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	360	420
Derivative Asset, Fair Value, Gross Asset	101	22
Derivative Liability, Fair Value, Gross Liability	0	0
Derivatives Designated as Hedging Instruments: | Cash flow hedges: | Foreign currency swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	2,811	2,765
Derivative Asset, Fair Value, Gross Asset	492	190
Derivative Liability, Fair Value, Gross Liability	1	27
Derivatives Not Designated or Not Qualifying as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	97,842	110,287
Derivative Asset, Fair Value, Gross Asset	5,557	2,809
Derivative Liability, Fair Value, Gross Liability	2,250	2,510
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Interest rate swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,434	7,559
Derivative Asset, Fair Value, Gross Asset	746	878
Derivative Liability, Fair Value, Gross Liability	9	29
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Interest rate caps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	2,350	3,350
Derivative Asset, Fair Value, Gross Asset	1	2
Derivative Liability, Fair Value, Gross Liability	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Interest rate options
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	24,170	29,750
Derivative Asset, Fair Value, Gross Asset	2,306	782
Derivative Liability, Fair Value, Gross Liability	256	187
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Interest rate forwards
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	7,160	5,418
Derivative Asset, Fair Value, Gross Asset	1,349	94
Derivative Liability, Fair Value, Gross Liability	0	114
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Foreign currency swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,020	1,051
Derivative Asset, Fair Value, Gross Asset	186	96
Derivative Liability, Fair Value, Gross Liability	14	15
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Foreign currency forwards
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	147	138
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	0	1
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Credit default swaps — purchased
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	18	18
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	0	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Credit default swaps — written
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,788	1,635
Derivative Asset, Fair Value, Gross Asset	19	36
Derivative Liability, Fair Value, Gross Liability	2	0
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Equity index options
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	46,537	51,509
Derivative Asset, Fair Value, Gross Asset	834	850
Derivative Liability, Fair Value, Gross Liability	1,246	1,728
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Equity variance swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,098	2,136
Derivative Asset, Fair Value, Gross Asset	11	69
Derivative Liability, Fair Value, Gross Liability	27	69
Derivatives Not Designated or Not Qualifying as Hedging Instruments: | Equity total return swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	10,120	7,723
Derivative Asset, Fair Value, Gross Asset	105	2
Derivative Liability, Fair Value, Gross Liability	696	367
Ceded guaranteed minimum benefits
Derivatives, Fair Value [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Asset	323	217
Embedded Derivative, Fair Value of Embedded Derivative Liability	0	0
Direct guaranteed minimum benefits
Derivatives, Fair Value [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Asset	0	0
Embedded Derivative, Fair Value of Embedded Derivative Liability	3,813	1,656
Direct index-linked annuities
Derivatives, Fair Value [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Asset	0	0
Embedded Derivative, Fair Value of Embedded Derivative Liability	1,526	2,253
Direct index-linked annuities | Assumed index-linked annuities
Derivatives, Fair Value [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Asset	0	0
Embedded Derivative, Fair Value of Embedded Derivative Liability	$ 310	$ 339