Derivative Instruments (Gross Notional Amount and Fair Value of Derivatives Contracts) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Notional Amount	$ 20,302	$ 19,446
Carrying Value / Fair Value of Assets	307	258
Derivative Liability, Fair Value, Gross Liability	1,330	1,003
Not Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	18,433	17,475
Carrying Value / Fair Value of Assets	169	212
Derivative Liability, Fair Value, Gross Liability	1,253	970
Not Designated as Hedging Instrument \| Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount	1,057	909
Carrying Value / Fair Value of Assets	104	70
Derivative Liability, Fair Value, Gross Liability	8	3
Not Designated as Hedging Instrument \| Financial Futures
Derivative [Line Items]
Notional Amount	323	307
Carrying Value / Fair Value of Assets	0	0
Derivative Liability, Fair Value, Gross Liability	0	0
Not Designated as Hedging Instrument \| Foreign Currency Forwards
Derivative [Line Items]
Notional Amount	175	175
Carrying Value / Fair Value of Assets	3	1
Derivative Liability, Fair Value, Gross Liability	0	0
Not Designated as Hedging Instrument \| Consumer Price Index Swap [Member]
Derivative [Line Items]
Notional Amount	527	441
Carrying Value / Fair Value of Assets	1	0
Derivative Liability, Fair Value, Gross Liability	65	28
Not Designated as Hedging Instrument \| Credit Default Swaps
Derivative [Line Items]
Notional Amount	1,641	1,306
Carrying Value / Fair Value of Assets	3	5
Derivative Liability, Fair Value, Gross Liability	6	0
Not Designated as Hedging Instrument \| Equity Options
Derivative [Line Items]
Notional Amount	320	364
Carrying Value / Fair Value of Assets	58	15
Derivative Liability, Fair Value, Gross Liability	0	0
Not Designated as Hedging Instrument \| Synthetic Guaranteed Investment Contracts
Derivative [Line Items]
Notional Amount	14,240	13,823
Carrying Value / Fair Value of Assets	0	0
Derivative Liability, Fair Value, Gross Liability	0	0
Not Designated as Hedging Instrument \| Embedded Derivatives In Modified Coinsurance Or Funds Withheld Arrangements
Derivative [Line Items]
Notional Amount	0	0
Carrying Value / Fair Value of Assets	0	121
Derivative Liability, Fair Value, Gross Liability	109	0
Not Designated as Hedging Instrument \| Embedded Derivatives In Indexed Annuity [Member]
Derivative [Line Items]
Notional Amount	0	0
Carrying Value / Fair Value of Assets	0	0
Derivative Liability, Fair Value, Gross Liability	751	767
Not Designated as Hedging Instrument \| Embedded Derivatives In Variable Annuity [Member]
Derivative [Line Items]
Notional Amount	0	0
Carrying Value / Fair Value of Assets	0	0
Derivative Liability, Fair Value, Gross Liability	291	163
Not Designated as Hedging Instrument \| Currency Swap [Member]
Derivative [Line Items]
Notional Amount	150	150
Carrying Value / Fair Value of Assets	0	0
Derivative Liability, Fair Value, Gross Liability	23	9
Designated As Hedging Instrument
Derivative [Line Items]
Notional Amount	1,869	1,971
Carrying Value / Fair Value of Assets	138	46
Derivative Liability, Fair Value, Gross Liability	77	33
Designated As Hedging Instrument \| Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount	435	535
Carrying Value / Fair Value of Assets	5	1
Derivative Liability, Fair Value, Gross Liability	53	29
Designated As Hedging Instrument \| Currency Swap [Member]
Derivative [Line Items]
Notional Amount	322	342
Carrying Value / Fair Value of Assets	31	17
Derivative Liability, Fair Value, Gross Liability	23	2
Designated As Hedging Instrument \| Forward Contracts [Member]
Derivative [Line Items]
Notional Amount	1,112	1,094
Carrying Value / Fair Value of Assets	102	28
Derivative Liability, Fair Value, Gross Liability	$ 1	$ 2

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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- Definition

Nominal or face amount used to calculate payment on derivative.

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