Segment Reporting (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($) level3FinancialInstruments	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Segment Reporting, Revenue Reconciling Item [Line Items]
Number of Reportable Segments | level3FinancialInstruments			3
Revenues	$ 80	$ 51	$ 286	$ 229
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	342	19	352	21
Provision for income taxes	2	2	4	15
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	340	17	348	6
Premiums Earned, Net	11	11	39	36
Net Investment Income	11	21	(6)	112
Amortization of intangible assets	6	11	34	44
Interest Expense	49	44	138	144
Total assets	9,412	12,228	9,412	12,228	$ 12,303
Premiums Written, Net	0	(15)	21	(36)
Derivative, Gain (Loss) on Derivative, Net	37	5	124	19
Net realized gains (losses) on extinguishment of debt	0	0	57	33
Insurance Commissions and Fees	7	7	22	20
Other revenues, operating	14	7	50	9
Losses and loss expenses (benefit)	(353)	(55)	(341)	(73)
Other Cost and Expense, Operating	32	28	90	82
Insurance Commissions	4	4	13	11
Depreciation	0	0	1	1
Benefits, Losses and Expenses	(262)	32	(66)	208
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest		0	(1)	(1)
Net income attributable to common shareholders	340	17	347	5
Financial Guarantee
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	67	44	250	204
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	349	27	362	35
Premiums Earned, Net	7	11	31	36
Net Investment Income	9	21	(9)	111
Amortization of intangible assets	5	10	32	42
Interest Expense	49	44	138	144
Total assets	8,902	11,837	8,902	11,837
Derivative, Gain (Loss) on Derivative, Net	37	5	123	19
Net realized gains (losses) on extinguishment of debt		0	57	33
Other revenues, operating	13	7	48	5
Losses and loss expenses (benefit)	(356)	(55)	(347)	(73)
Other Cost and Expense, Operating	20	18	64	56
Depreciation	0	0	1	1
Benefits, Losses and Expenses	(282)	17	(112)	169
Specialty Property & Casualty Program
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	6	0	11	1
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(1)	(2)	(5)	(4)
Premiums Earned, Net	4	0	8	0
Net Investment Income	0	0	1	1
Total assets	259	113	259	113
Other revenues, operating	1	0	2	0
Losses and loss expenses (benefit)	3	0	5	0
Other Cost and Expense, Operating	4	2	11	5
Depreciation	0	0	0	0
Benefits, Losses and Expenses	7	2	16	5
Managing General Agency Underwriter
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	7	7	22	20
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	1	1	3	3
Amortization of intangible assets	1	1	2	2
Total assets	94	96	94	96
Insurance Commissions and Fees	7	7	22	20
Other revenues, operating	0	0	0	0
Other Cost and Expense, Operating	1	1	4	4
Insurance Commissions	4	4	13	11
Depreciation	0	0	0	0
Benefits, Losses and Expenses	6	6	19	17
Corporate and Other
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1	0	2	4
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(6)	(6)	(8)	(12)
Net Investment Income	1	0	2	0
Total assets	157	183	157	183
Derivative, Gain (Loss) on Derivative, Net	0		1
Other revenues, operating	0	0	0	4
Other Cost and Expense, Operating	6	6	11	17
Depreciation	0	0	0	0
Benefits, Losses and Expenses	6	6	11	17
Surplus Notes	$ 69	$ 103	$ 69	$ 103