Background and Basis of Presentation - Surplus Note Exchange (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
Insurance [Line Items]
Net realized gains on extinguishment of debt									$ (497)	$ 19	$ (13,710)
Realized Investment Gains (Losses)	$ (4,455)	$ (577)	$ 4,535	$ 0	$ 1	$ 0	$ (20)	$ 38	(497)	19	(62)
Parent Company [Member]
Insurance [Line Items]
Realized Investment Gains (Losses)									$ (498)	$ 55	$ (13,664)
Ambac Assurance Corporation | 5.1% Surplus Notes, General Account, Due 2020
Insurance [Line Items]
Debt instrument, interest rate	5.10%								5.10%