Segment Reporting (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) level3FinancialInstruments	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)
Segment Reporting, Revenue Reconciling Item [Line Items]
Number of Reportable Segments | level3FinancialInstruments			3
Revenues	$ 114,000	$ 74,000	$ 321,000	$ 194,000
Policyholder Benefits and Claims Incurred, Net	38,000	(76,000)	54,000	(51,000)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(27,000)	68,000	1,000	28,000
Provision for income taxes	3,000	1,000	10,000	7,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(29,000)	66,000	(9,000)	21,000
Premiums Earned, Net	33,000	18,000	99,000	47,000
Net Investment Income	38,000	30,000	116,000	100,000
Amortization of Intangible Assets	13,000	7,000	33,000	21,000
Interest Expense	20,000	16,000	51,000
Total assets	9,256,000	7,847,000	9,256,000	7,847,000	$ 8,428,000
Premiums Written, Net	31,000	27,000	92,000	0
Derivative, Gain (Loss) on Derivative, Net	5,000	4,000	7,000	1,000
Insurance Commissions and Fees	23,000	15,000	54,000	39,000
Losses and loss adjustment expenses (benefit)			54,000	(51,000)
Other Cost and Expense, Operating	55,000	49,000	137,000	120,000
Insurance Commissions	9,000	8,000	27,000	22,000
Depreciation	1,000	0	2,000	1,000
Benefits, Losses and Expenses	141,000	6,000	320,000	166,000
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest	2,000	0	1,000	(1,000)
Net income attributable to common shareholders	(28,000)	66,000	(8,000)	19,000
Realized Investment Gains (Losses)	(1,000)	1,000	3,000	(7,000)
Contractually Specified Servicing Fee, Late Fee, and Ancillary Fee Earned in Exchange for Servicing Financial Asset	4,000	2,000	10,000	6,000
Other income Items	13,000	3,000	33,000	7,000
Deferred Policy Acquisition Costs, Amortization Expense	6,000	2,000	16,000	5,000
Financial Guarantee
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	44,000	41,000	151,000	112,000
Policyholder Benefits and Claims Incurred, Net	17,000	(86,000)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(9,000)	69,000	28,000	29,000
Premiums Earned, Net	6,000	6,000	19,000	20,000
Net Investment Income	34,000	27,000	105,000	90,000
Amortization of Intangible Assets	6,000	6,000	25,000	18,000
Interest Expense	16,000	16,000	48,000	48,000
Total assets	7,358,000	7,018,000	7,358,000	7,018,000
Derivative, Gain (Loss) on Derivative, Net	(1,000)	4,000	1,000	2,000
Losses and loss adjustment expenses (benefit)			(9,000)	(71,000)
Other Cost and Expense, Operating	14,000	35,000	58,000	87,000
Depreciation	0	0	1,000	1,000
Benefits, Losses and Expenses	54,000	(28,000)	122,000	83,000
Realized Investment Gains (Losses)	(1,000)	1,000	(1,000)	(7,000)
Other income Items	6,000	3,000	27,000	7,000
Deferred Policy Acquisition Costs, Amortization Expense	0	0	0	0
Specialty Property & Casualty Program
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	40,000	16,000	102,000	35,000
Policyholder Benefits and Claims Incurred, Net	20,000	10,000
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	9,000	0	10,000	(1,000)
Premiums Earned, Net	27,000	12,000	80,000	27,000
Net Investment Income	2,000	1,000	5,000	3,000
Total assets	812,000	457,000	812,000	457,000
Losses and loss adjustment expenses (benefit)			63,000	20,000
Other Cost and Expense, Operating	5,000	4,000	13,000	12,000
Depreciation	0	0	0	0
Benefits, Losses and Expenses	31,000	15,000	92,000	36,000
Realized Investment Gains (Losses)	0	0	0	0
Managing General Agency Underwriter
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	24,000	15,000	55,000	39,000
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(8,000)	2,000	(3,000)	7,000
Net Investment Income	0	0	0
Amortization of Intangible Assets	6,000	1,000	9,000	3,000
Interest Expense	4,000		4,000
Total assets	937,000	160,000	937,000	160,000
Derivative, Gain (Loss) on Derivative, Net	2,000		2,000
Insurance Commissions and Fees	23,000	15,000	54,000	39,000
Other Cost and Expense, Operating	12,000	3,000	18,000	7,000
Insurance Commissions	9,000	8,000	27,000	22,000
Depreciation	0	0	0	0
Benefits, Losses and Expenses	32,000	12,000	58,000	33,000
Corporate and Other
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	6,000	3,000	14,000	7,000
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(18,000)	(4,000)	(34,000)	(8,000)
Net Investment Income	2,000	3,000	6,000	7,000
Total assets	150,000	213,000	150,000	213,000
Derivative, Gain (Loss) on Derivative, Net	5,000	0	4,000	0
Other Cost and Expense, Operating	24,000	7,000	47,000	14,000
Depreciation	0	0	1,000	0
Benefits, Losses and Expenses	24,000	7,000	48,000	14,000
Realized Investment Gains (Losses)	(1,000)	0	4,000	0
Other income Items	0	0	0	0
Property and Casualty, Commercial Insurance
Segment Reporting, Revenue Reconciling Item [Line Items]
Contractually Specified Servicing Fee, Late Fee, and Ancillary Fee Earned in Exchange for Servicing Financial Asset	4,000	2,000	10,000	6,000
Other income Items	7,000	0	7,000	0
Deferred Policy Acquisition Costs, Amortization Expense	6,000	2,000	16,000	5,000
Insurance Distribution
Segment Reporting, Revenue Reconciling Item [Line Items]
Other income Items	$ (1,000)	$ 0	$ (1,000)	$ 0