Fair Value (Unobservable Input Reconciliation) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Net Derivatives (2)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance, beginning of period	$ 2	$ 16
Total realized/unrealized gains (losses) included in net income (loss) (5) (6)	8	1
Total realized/unrealized gains (losses) included in AOCI	(1)	31
Purchases (7)	(2)	0
Sales (7)	0	2
Issuances (7)	0	0
Settlements (7)	0	0
Transfers into Level 3 (8)	0	0
Transfers out of Level 3 (8)	1	0
Balance, end of period	8	50
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	8	1
Changes in unrealized gains (losses) included in other comprehensive income for the instruments still held at end of period	(1)	30
Net Embedded Derivatives (3)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance, beginning of period	(7,301)	(4,365)
Total realized/unrealized gains (losses) included in net income (loss) (5) (6)	665	(233)
Total realized/unrealized gains (losses) included in AOCI	0	0
Purchases (7)	0	0
Sales (7)	0	0
Issuances (7)	0	0
Settlements (7)	(138)	(149)
Transfers into Level 3 (8)	0	0
Transfers out of Level 3 (8)	0	0
Balance, end of period	(6,774)	(4,747)
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	663	(242)
Changes in unrealized gains (losses) included in other comprehensive income for the instruments still held at end of period	0	0
Corporate (1)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	684	457
Total realized/unrealized gains (losses) included in net income (loss) (5) (6)	(1)	(2)
Total realized/unrealized gains (losses) included in AOCI	(22)	(44)
Purchases (7)	118	249
Sales (7)	(4)	(11)
Issuances (7)	0	0
Settlements (7)	0	0
Transfers into Level 3 (8)	4	220
Transfers out of Level 3 (8)	(112)	(31)
Balance, end of period	667	838
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(1)	(1)
Changes in unrealized gains (losses) included in other comprehensive income for the instruments still held at end of period	(22)	(44)
Structured Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	67	117
Total realized/unrealized gains (losses) included in net income (loss) (5) (6)	0	0
Total realized/unrealized gains (losses) included in AOCI	0	(8)
Purchases (7)	80	65
Sales (7)	(3)	(6)
Issuances (7)	0	0
Settlements (7)	0	0
Transfers into Level 3 (8)	3	68
Transfers out of Level 3 (8)	(21)	(18)
Balance, end of period	126	218
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0
Changes in unrealized gains (losses) included in other comprehensive income for the instruments still held at end of period	0	(8)
State and Political Subdivision
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	0	73
Total realized/unrealized gains (losses) included in net income (loss) (5) (6)	0	0
Total realized/unrealized gains (losses) included in AOCI	0	0
Purchases (7)	0	0
Sales (7)	0	(1)
Issuances (7)	0	0
Settlements (7)	0	0
Transfers into Level 3 (8)	0	0
Transfers out of Level 3 (8)	0	0
Balance, end of period	0	72
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0
Changes in unrealized gains (losses) included in other comprehensive income for the instruments still held at end of period	0	0
Foreign government
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	0	0
Total realized/unrealized gains (losses) included in net income (loss) (5) (6)	0	0
Total realized/unrealized gains (losses) included in AOCI	0	0
Purchases (7)	0	7
Sales (7)	0	0
Issuances (7)	0	0
Settlements (7)	0	0
Transfers into Level 3 (8)	0	0
Transfers out of Level 3 (8)	0	0
Balance, end of period	0	7
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0
Changes in unrealized gains (losses) included in other comprehensive income for the instruments still held at end of period	0	0
Equity Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	3	8
Total realized/unrealized gains (losses) included in net income (loss) (5) (6)	0	0
Total realized/unrealized gains (losses) included in AOCI	0	0
Purchases (7)	0	0
Sales (7)	0	0
Issuances (7)	0	0
Settlements (7)	0	0
Transfers into Level 3 (8)	0	0
Transfers out of Level 3 (8)	0	(4)
Balance, end of period	3	4
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0
Changes in unrealized gains (losses) included in other comprehensive income for the instruments still held at end of period	0	0
Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	0	5
Total realized/unrealized gains (losses) included in net income (loss) (5) (6)	0	0
Total realized/unrealized gains (losses) included in AOCI	0	0
Purchases (7)	0	0
Sales (7)	0	(3)
Issuances (7)	0	0
Settlements (7)	0	0
Transfers into Level 3 (8)	0	0
Transfers out of Level 3 (8)	0	0
Balance, end of period	0	2
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0
Changes in unrealized gains (losses) included in other comprehensive income for the instruments still held at end of period	0	0
Separate Account Assets (4)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	3	3
Total realized/unrealized gains (losses) included in net income (loss) (5) (6)	0	0
Total realized/unrealized gains (losses) included in AOCI	0	(1)
Purchases (7)	0	1
Sales (7)	(1)	0
Issuances (7)	0	0
Settlements (7)	0	0
Transfers into Level 3 (8)	0	1
Transfers out of Level 3 (8)	0	0
Balance, end of period	2	4
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0
Changes in unrealized gains (losses) included in other comprehensive income for the instruments still held at end of period	$ 0	$ 0

Amount of unrealized gain (loss) recognized in other comprehensive income (OCI) from asset (liability) measured at fair value on recurring basis using unobservable input (level 3) and still held.

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Amount of unrealized gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3) and still held.

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Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of transfer of financial instrument classified as an asset into level 3 of the fair value hierarchy.

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Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of unrealized gain (loss) recognized in income for derivative asset (liability) after deduction of derivative liability (asset), measured at fair value using unobservable input (level 3) and still held.

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Amount of gain (loss) recognized in income from derivative asset (liability) after deduction of derivative liability (asset), measured at fair value on recurring basis using unobservable input (level 3).

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Amount of gain (loss) recognized in other comprehensive income from derivative asset (liability) after deduction of derivative liability (asset), measured at fair value on recurring basis using unobservable input (level 3).

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Amount of issuances of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of purchases of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of sales of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlements of financial instrument classified as a derivative asset (liability) after deduction of derivative liability, measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of transfers of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset) into level 3 of the fair value hierarchy.

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Amount of transfers of financial instrument classified as derivative asset (liability) after deduction of derivative liability (asset) out of level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of unrealized gain (loss) recognized in other comprehensive income (OCI) from derivative asset (liability) after deduction of derivative liability (asset), measured at fair value using unobservable input (level 3) and still held.

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