Fair Value Measurement - Fair Value Level 3 Rollforward Recurring Basis (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
FG VIEs’ Assets
Fair Value Level 3 Rollforward
Fair value at beginning of period	$ 197	$ 267	$ 204	$ 260
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	(2)	1	(1)	(3)
Other comprehensive income (loss)	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	(7)	(26)	(15)	(34)
Consolidations				15
Deconsolidations		15		(15)
Transfers out of Level 3		4
Fair value at end of period	188	223	188	223
Change in unrealized gains/(losses) related to financial instruments held	(3)	2	(3)	(2)
Consolidated Investment Vehicles \| Equity securities and warrants
Fair Value Level 3 Rollforward
Fair value at beginning of period	329	243	297
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	7	16	40
Other comprehensive income (loss)	0	0	0
Purchases	34	5	38
Sales	(80)	(6)	(85)
Settlements	0	0	0
Deconsolidations		0
Transfers out of Level 3		0
Fair value at end of period	290	258	290	258
Change in unrealized gains/(losses) related to financial instruments held	(33)	10	(1)
Consolidated Investment Vehicles \| Equity Securities
Fair Value Level 3 Rollforward
Fair value at beginning of period				239
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)				26
Other comprehensive income (loss)				0
Purchases				5
Sales				(12)
Settlements				0
Consolidations				0
Deconsolidations				0
Fair value at end of period		258		258
Change in unrealized gains/(losses) related to financial instruments held				18
Consolidated Investment Vehicles \| Corporate securities
Fair Value Level 3 Rollforward
Fair value at beginning of period	93	83	96	91
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	(1)	7	(3)	6
Other comprehensive income (loss)	0	0	0	0
Purchases	2	0	6	1
Sales	(10)	0	(15)	(8)
Settlements	0	0	0	0
Consolidations				0
Deconsolidations		0		0
Transfers out of Level 3		0
Fair value at end of period	84	90	84	90
Change in unrealized gains/(losses) related to financial instruments held	0	7	(3)	5
Consolidated Investment Vehicles \| Structured products
Fair Value Level 3 Rollforward
Fair value at beginning of period	17	0	46	0
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	0	(3)	2	(3)
Other comprehensive income (loss)	0	0	0	0
Purchases	0	42	0	42
Sales	(17)	(21)	(48)	(21)
Settlements	0	0	0	0
Consolidations				0
Deconsolidations		(20)		20
Transfers out of Level 3		0
Fair value at end of period	0	38	0	38
Change in unrealized gains/(losses) related to financial instruments held	0	(3)	0	(3)
Other
Fair Value Level 3 Rollforward
Fair value at beginning of period	34	28	50	27
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	3	10	(13)	11
Other comprehensive income (loss)	0	(1)	0	(1)
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	(4)	0	(4)	0
Consolidations				0
Deconsolidations		0		0
Transfers out of Level 3		0
Fair value at end of period	33	37	33	37
Change in unrealized gains/(losses) related to financial instruments held	3	10	(13)	11
Other \| Other Comprehensive Income (Loss)
Total pre-tax realized and unrealized gains (losses) recorded in:
Change in unrealized gains/(losses) related to financial instruments held	0	(1)	0	(1)
Financial Guaranty Variable Interest Entities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value at start of period	(704)	(335)	(715)	(289)
Total Pretax Realized And Unrealized Gains (Losses) Recorded As Liabilities [Abstract]
Net income (loss)	(2)	11	1	26
Other comprehensive income (loss)	2	3	1	3
Issuances		0		0
Settlements	5	24	14	65
Consolidations				(102)
Deconsolidations		15		15
Fair value at end of period	(699)	(282)	(699)	(282)
Change in unrealized gains/(losses) included in earnings related to financial instruments	4	11	2	49
Change in unrealized gains/(losses) included in OCI related to financial instruments	2	3	1	3
Liabilities of CIVs
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value at start of period	(4,220)	(3,650)	(4,154)	(3,705)
Total Pretax Realized And Unrealized Gains (Losses) Recorded As Liabilities [Abstract]
Net income (loss)	17	250	(45)	295
Other comprehensive income (loss)	(5)	37	(13)	56
Issuances		(1,027)		(1,408)
Settlements	9	29	13	401
Consolidations				0
Deconsolidations		374		374
Fair value at end of period	(4,199)	(3,987)	(4,199)	(3,987)
Change in unrealized gains/(losses) included in earnings related to financial instruments	(2)	262	(67)	303
Change in unrealized gains/(losses) included in OCI related to financial instruments	(5)	37	(13)	56
Obligations of state and political subdivisions \| Fixed-maturity securities, available-for-sale
Fair Value Level 3 Rollforward
Fair value at beginning of period	47	70	47	72
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	1	(1)	1	0
Other comprehensive income (loss)	(1)	(3)	0	(8)
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	(1)	(14)	(2)	(13)
Consolidations				0
Deconsolidations		0		0
Transfers out of Level 3		1
Fair value at end of period	46	51	46	51
Obligations of state and political subdivisions \| Fixed-maturity securities, available-for-sale \| Other Comprehensive Income (Loss)
Total pre-tax realized and unrealized gains (losses) recorded in:
Change in unrealized gains/(losses) related to financial instruments held	(1)	(4)	0	(10)
RMBS \| Fixed-maturity securities, available-for-sale
Fair Value Level 3 Rollforward
Fair value at beginning of period	174	200	179	216
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	4	6	7	10
Other comprehensive income (loss)	(7)	(11)	(8)	(19)
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	(9)	(11)	(16)	(23)
Consolidations				0
Deconsolidations		0		0
Transfers out of Level 3		0
Fair value at end of period	162	184	162	184
RMBS \| Fixed-maturity securities, available-for-sale \| Other Comprehensive Income (Loss)
Total pre-tax realized and unrealized gains (losses) recorded in:
Change in unrealized gains/(losses) related to financial instruments held	(7)	(10)	(8)	(17)
Asset-backed securities \| Fixed-maturity securities, available-for-sale
Fair Value Level 3 Rollforward
Fair value at beginning of period	795	842	794	863
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	(3)	(3)	0	0
Other comprehensive income (loss)	(5)	(30)	(8)	(37)
Purchases	18	10	23	35
Sales	(2)	(9)	(2)	(12)
Settlements	(3)	(5)	(7)	(44)
Consolidations				0
Deconsolidations		0		0
Transfers out of Level 3		0
Fair value at end of period	800	805	800	805
Asset-backed securities \| Fixed-maturity securities, available-for-sale \| Other Comprehensive Income (Loss)
Total pre-tax realized and unrealized gains (losses) recorded in:
Change in unrealized gains/(losses) related to financial instruments held	(4)	(29)	(7)	(36)
Credit Risk Contract
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair value at start of period	(148)	(156)	(162)	(154)
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	91	9	106	6
Other comprehensive income (loss)	0	0	0	0
Issuances		0		0
Settlements	0	0	(1)	1
Consolidations				0
Deconsolidations		0		0
Fair value at end of period	(57)	(147)	(57)	(147)
Change in unrealized gains/(losses) included in earnings related to financial instruments	$ 91	$ 8	$ 105	$ 5

Fair Value, Measured with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Deconsolidation

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Total Pretax Realized And Unrealized Gains (Losses) Recorded As Assets [Abstract]

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

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

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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 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 gain (loss) recognized in income from liability 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 (OCI) from liability measured at fair value on recurring basis using unobservable input (level 3).

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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 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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