Derivatives (Primary Risks Managed by Derivatives) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$ 113,375	$ 92,676
Derivative assets	3,222	2,993
Derivative liabilities	7,119	4,628
Embedded Derivative, Fair Value of Embedded Derivative Asset	217	228
Embedded Derivative, Fair Value of Embedded Derivative Liability	4,582	2,516
Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,121	2,461
Derivative assets	198	200
Derivative liabilities	27	30
Derivatives Not Designated or Not Qualifying as hedging Instruments
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	110,254	90,215
Derivative assets	2,807	2,565
Derivative liabilities	2,510	2,082
Derivatives Not Designated or Not Qualifying as hedging Instruments | Interest rate swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	7,559	10,747
Derivative assets	878	528
Derivative liabilities	29	558
Derivatives Not Designated or Not Qualifying as hedging Instruments | Interest rate caps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,350	3,350
Derivative assets	2	21
Derivative liabilities	0	0
Derivatives Not Designated or Not Qualifying as hedging Instruments | Interest rate futures
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	0	53
Derivative assets	0	0
Derivative liabilities	0	0
Derivatives Not Designated or Not Qualifying as hedging Instruments | Interest rate options
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	29,750	17,168
Derivative assets	782	168
Derivative liabilities	187	61
Derivatives Not Designated or Not Qualifying as hedging Instruments | Interest rate forwards
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	5,418	0
Derivative assets	94	0
Derivative liabilities	114	0
Derivatives Not Designated or Not Qualifying as hedging Instruments | Foreign currency swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,040	1,398
Derivative assets	94	99
Derivative liabilities	15	18
Derivatives Not Designated or Not Qualifying as hedging Instruments | Foreign currency forwards
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	138	125
Derivative assets	0	0
Derivative liabilities	1	0
Derivatives Not Designated or Not Qualifying as hedging Instruments | Credit default swaps — purchased
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	18	98
Derivative assets	0	3
Derivative liabilities	0	0
Derivatives Not Designated or Not Qualifying as hedging Instruments | Credit default swaps — written
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,613	1,798
Derivative assets	36	14
Derivative liabilities	0	3
Derivatives Not Designated or Not Qualifying as hedging Instruments | Equity futures
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	0	169
Derivative assets	0	0
Derivative liabilities	0	0
Derivatives Not Designated or Not Qualifying as hedging Instruments | Equity index options
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	51,509	45,815
Derivative assets	850	1,372
Derivative liabilities	1,728	1,207
Derivatives Not Designated or Not Qualifying as hedging Instruments | Equity variance swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	2,136	5,574
Derivative assets	69	80
Derivative liabilities	69	232
Derivatives Not Designated or Not Qualifying as hedging Instruments | Equity total return swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	7,723	3,920
Derivative assets	2	280
Derivative liabilities	367	3
Ceded guaranteed minimum income benefits
Derivatives, Fair Value [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Asset	217	228
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	1,548	1,546
Assumed 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	442	386
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	2,253	488
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	339	96
Cash Flow Hedging | Derivatives Designated as Hedging Instruments | Interest rate forwards
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	420	0
Derivative assets	22	0
Derivative liabilities	0	0
Cash Flow Hedging | Derivatives Designated as Hedging Instruments | Foreign currency swaps
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	2,701	2,461
Derivative assets	176	200
Derivative liabilities	$ 27	$ 30