Financial Guarantee Insurance Contracts Financial Guarantee Insurance Contracts - Components of Loss and Loss Expense Reserves and Subrogation Recoverable (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Components of Loss and Loss Expense Reserves and Subrogation Recoverable [Line Items]
Policyholder Benefits and Claims Incurred, Ceded									$ 191,151	$ 113,622	$ 52,960
Liability for Unpaid Claims and Claims Adjustment Expense, Net	$ 78,981				$ 40,788				78,981	40,788	9,752	$ 474
Liability for Claims and Claims Adjustment Expense	349,062				197,089				349,062	197,089
Liabillity for Claim and Claim Adjustment Expense, with Impact of VIE Consolidation	349,062				197,089				349,062	197,089	89,907	$ 32,169
Net premiums earned	$ 18,931	$ 27,441	$ 27,054	$ 25,579	$ 24,945	$ 12,187	$ 7,785	$ 6,995	$ 99,005	$ 51,911	$ 13,869