Investments - Net Investment Income and Equity in Earnings of Investees (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Net Investment Income
Gross investment income	$ 64	$ 70	$ 127	$ 141
Investment expenses	(2)	(2)	(3)	(3)
Net investment income	62	68	124	138
Fair value gains (losses) on trading securities	(18)	0	(22)	0
Fair value loss on trading securities still held	(12)		(16)
Segment equity in earnings (losses) of investees	0	34	(11)	43
Fair Value Measured at Net Asset Value Per Share
Net Investment Income
Segment equity in earnings (losses) of investees		26	3	26
Dividends received			5
Externally managed
Net Investment Income
Gross investment income	47	52	95	103
Loss mitigation securities and other
Net Investment Income
Gross investment income	12	14	23	30
AssuredIM managed fixed-maturity securities
Net Investment Income
Gross investment income	$ 5	$ 4	$ 9	$ 8

Amount of unrealized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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Amount of dividend income on investment in equity security, classified as operating.

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

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Amount of income (loss) for proportionate share of equity method investee's income (loss).

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Represents the total of interest and dividend income, including any amortization and accretion (as applicable) of discounts and premiums, earned from (1) loans and leases whether held-for-sale or held-in-portfolio; (2) investment securities; (3) federal funds sold; (4) securities purchased under agreements to resell; (5) investments in banker's acceptances, commercial paper, or certificates of deposit; (6) dividend income; or (7) other investments not otherwise specified herein.

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Amount of expenses related to the generation of investment income.

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Amount, after investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

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