Fair Value Measurement - Fair Value Level 3 Rollforward Recurring Basis (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023
FG VIEs’ Assets
Fair Value Level 3 Rollforward
Fair value at beginning of period	$ 174	$ 204
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	(2)	1
Other comprehensive income (loss)	1	0
Purchases	0	0
Sales	0	0
Settlements	(6)	(8)
Transfers into Level 3	0
Fair value at end of period	167	197
Change in unrealized gains/(losses) related to financial instruments held	(3)	0
Consolidated Investment Vehicles \| Equity securities and warrants
Fair Value Level 3 Rollforward
Fair value at beginning of period	80
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	8
Other comprehensive income (loss)	0
Purchases	0
Sales	(2)
Settlements	0
Transfers into Level 3	3
Fair value at end of period	89
Change in unrealized gains/(losses) related to financial instruments held	7
Consolidated Investment Vehicles \| Equity Securities and Warrants
Fair Value Level 3 Rollforward
Fair value at beginning of period		297
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)		33
Other comprehensive income (loss)		0
Purchases		4
Sales		(5)
Settlements		0
Fair value at end of period		329
Change in unrealized gains/(losses) related to financial instruments held		32
Consolidated Investment Vehicles \| Corporate securities
Fair Value Level 3 Rollforward
Fair value at beginning of period		96
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)		(2)
Other comprehensive income (loss)		0
Purchases		4
Sales		(5)
Settlements		0
Fair value at end of period		93
Change in unrealized gains/(losses) related to financial instruments held		(3)
Consolidated Investment Vehicles \| Structured products
Fair Value Level 3 Rollforward
Fair value at beginning of period	189	46
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	4	2
Other comprehensive income (loss)	0	0
Purchases	29	0
Sales	(12)	(31)
Settlements	0	0
Transfers into Level 3	10
Fair value at end of period	220	17
Change in unrealized gains/(losses) related to financial instruments held	5	0
Other
Fair Value Level 3 Rollforward
Fair value at beginning of period	14	50
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	(10)	(16)
Other comprehensive income (loss)	1	0
Purchases	0	0
Sales	0	0
Settlements	0	0
Transfers into Level 3	0
Fair value at end of period	5	34
Change in unrealized gains/(losses) related to financial instruments held	(10)	(16)
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	1	0
Financial Guaranty Variable Interest Entities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value at start of period	(554)	(715)
Total Pretax Realized And Unrealized Gains (Losses) Recorded As Liabilities [Abstract]
Net income (loss)	9	3
Other comprehensive income (loss)	(2)	(1)
Settlements	148	9
Fair value at end of period	(399)	(704)
Change in unrealized gains/(losses) included in earnings related to financial instruments	2	(2)
Change in unrealized gains/(losses) included in OCI related to financial instruments	(2)	(1)
Liabilities of CIVs (9)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value at start of period		(4,154)
Total Pretax Realized And Unrealized Gains (Losses) Recorded As Liabilities [Abstract]
Net income (loss)		(62)
Other comprehensive income (loss)		(8)
Settlements		4
Fair value at end of period		(4,220)
Change in unrealized gains/(losses) included in earnings related to financial instruments		(65)
Change in unrealized gains/(losses) included in OCI related to financial instruments		(8)
Obligations of state and political subdivisions \| Fixed-maturity securities, available-for-sale
Fair Value Level 3 Rollforward
Fair value at beginning of period	6	47
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	0	0
Other comprehensive income (loss)	0	1
Purchases	0	0
Sales	0	0
Settlements	0	(1)
Transfers into Level 3	0
Fair value at end of period	6	47
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	0	1
RMBS \| Fixed-maturity securities, available-for-sale
Fair Value Level 3 Rollforward
Fair value at beginning of period	154	179
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	3	3
Other comprehensive income (loss)	1	(1)
Purchases	0	0
Sales	0	0
Settlements	(5)	(7)
Transfers into Level 3	0
Fair value at end of period	153	174
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	1	(1)
Asset-backed securities \| Fixed-maturity securities, available-for-sale
Fair Value Level 3 Rollforward
Fair value at beginning of period	803	794
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	16	3
Other comprehensive income (loss)	2	(3)
Purchases	10	5
Sales	0	0
Settlements	(30)	(4)
Transfers into Level 3	20
Fair value at end of period	821	795
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	2	(3)
Credit Risk Contract
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair value at start of period	(50)	(162)
Total pre-tax realized and unrealized gains (losses) recorded in:
Net income (loss)	10	15
Other comprehensive income (loss)	0	0
Settlements	1	(1)
Fair value at end of period	(39)	(148)
Change in unrealized gains/(losses) included in earnings related to financial instruments	$ 4	$ 14

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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