Derivative Instruments (Gross Notional Amount and Fair Value of Derivatives Contracts) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Notional Amount of Derivatives	$ 23,298	$ 19,446
Derivative Asset, Fair Value, Gross Asset	229	258
Derivative Liability, Fair Value, Gross Liability	987	1,003
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional Amount of Derivatives	21,007	17,475
Derivative Asset, Fair Value, Gross Asset	208	212
Derivative Liability, Fair Value, Gross Liability	947	970
Not Designated as Hedging Instrument [Member] \| Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount of Derivatives	1,084	909
Derivative Asset, Fair Value, Gross Asset	93	70
Derivative Liability, Fair Value, Gross Liability	1	3
Not Designated as Hedging Instrument [Member] \| Future [Member]
Derivative [Line Items]
Notional Amount of Derivatives	258	307
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	0	0
Not Designated as Hedging Instrument [Member] \| Foreign Exchange Forward [Member]
Derivative [Line Items]
Notional Amount of Derivatives	347	175
Derivative Asset, Fair Value, Gross Asset	4	1
Derivative Liability, Fair Value, Gross Liability	2	0
Not Designated as Hedging Instrument [Member] \| Consumer Price Index Swap [Member]
Derivative [Line Items]
Notional Amount of Derivatives	612	441
Derivative Asset, Fair Value, Gross Asset	11	0
Derivative Liability, Fair Value, Gross Liability	19	28
Not Designated as Hedging Instrument [Member] \| Credit Default Swap [Member]
Derivative [Line Items]
Notional Amount of Derivatives	1,517	1,306
Derivative Asset, Fair Value, Gross Asset	13	5
Derivative Liability, Fair Value, Gross Liability	0	0
Not Designated as Hedging Instrument [Member] \| Equity [Member]
Derivative [Line Items]
Notional Amount of Derivatives	395	364
Derivative Asset, Fair Value, Gross Asset	29	15
Derivative Liability, Fair Value, Gross Liability	0	0
Not Designated as Hedging Instrument [Member] \| Synthetic Guaranteed Investment Contracts [Member]
Derivative [Line Items]
Notional Amount of Derivatives	16,644	13,823
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	0	0
Not Designated as Hedging Instrument [Member] \| Embedded Derivatives In Modified Coinsurance Or Funds Withheld Arrangements [Member]
Derivative [Line Items]
Notional Amount of Derivatives	0	0
Derivative Asset, Fair Value, Gross Asset	58	121
Derivative Liability, Fair Value, Gross Liability	0	0
Not Designated as Hedging Instrument [Member] \| Embedded Derivatives In Indexed Annuity [Member]
Derivative [Line Items]
Notional Amount of Derivatives	0	0
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	752	767
Not Designated as Hedging Instrument [Member] \| Embedded Derivatives In Variable Annuity [Member]
Derivative [Line Items]
Notional Amount of Derivatives	0	0
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	155	163
Not Designated as Hedging Instrument [Member] \| Currency Swap [Member]
Derivative [Line Items]
Notional Amount of Derivatives	150	150
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	18	9
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional Amount of Derivatives	2,291	1,971
Derivative Asset, Fair Value, Gross Asset	21	46
Derivative Liability, Fair Value, Gross Liability	40	33
Designated as Hedging Instrument [Member] \| Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount of Derivatives	802	535
Derivative Asset, Fair Value, Gross Asset	3	1
Derivative Liability, Fair Value, Gross Liability	24	29
Designated as Hedging Instrument [Member] \| Foreign Exchange Forward [Member]
Derivative [Line Items]
Notional Amount of Derivatives	1,255	1,094
Derivative Asset, Fair Value, Gross Asset	10	28
Derivative Liability, Fair Value, Gross Liability	15	2
Designated as Hedging Instrument [Member] \| Currency Swap [Member]
Derivative [Line Items]
Notional Amount of Derivatives	234	342
Derivative Asset, Fair Value, Gross Asset	8	17
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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