Net Income Per Share - Reconciliation of Net Income (Loss) Attributable to Common Stockholders to the Numerator in the Basic and Diluted Earnings Per Share Calculation (Details) - USD ($) $ / shares in Units, $ 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
Earnings Per Share [Abstract]
Net income (loss) attributable to Ambac common stockholders									$ (59,282)	$ (24,551)	$ (36,115)
Adjustment to redemption value (ASC 480)	$ 55,762	$ (2,402)	$ (184)	$ 53	$ 4,855	$ 19	$ (294)	$ 212	$ 53,210	$ 4,792	$ 2,469
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.70	$ (0.43)	$ (0.33)	$ (0.09)	$ (0.10)	$ (0.11)	$ (0.20)	$ (0.03)	$ (0.13)	$ (0.43)	$ (0.74)
Income (Loss) from Continuing Operations, Per Diluted Share	$ 0.70	$ (0.43)	$ (0.33)	$ (0.09)	$ (0.10)	$ (0.11)	$ (0.20)	$ (0.03)	$ (0.13)	$ (0.43)	$ (0.74)
Numerator of basic and diluted EPS	$ (492,503)	$ (29,906)	$ (934)	$ 20,123	$ (10,833)	$ 65,888	$ (13,426)	$ (33,205)	$ (6,072)	$ (19,759)	$ (33,646)