Insurance Contracts Financial Guarantee Insurance Contracts - Components of Loss and Loss Expense Reserves and Subrogation Recoverable (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024	Dec. 31, 2023
Components of Loss and Loss Expense Reserves and Subrogation Recoverable [Line Items]
Ceded Loss And Loss Expenses Paid Not Yet Recovered		$ 15,088
Policyholder Benefits and Claims Incurred, Ceded	$ (45,778)	(34,411)
Liability for Claims and Claims Adjustment Expense	373,105		$ 349,062
Liability for Claim and Claim Adjustment Expenses Net of Subrogation recoverables	$ 373,105	$ 237,014	$ 349,062	$ 197,089