DISCONTINUED OPERATION - Net Income (Loss) from Discontinued Operations (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
EXPENSES:
Net income (loss) from discontinued operations	$ (526,102)	$ (9,387)	$ 14,182	$ 24,140	$ 7,169	$ 66,190	$ (9,300)	$ (35,876)	$ (497,167)	$ 28,183	$ 557,364
Net income (loss) attributable to Ambac common shareholders									(497,167)	28,183	558,495
Ambac Assurance Corporation | Discontinued Operations, Held-for-Sale or Disposed of by Sale
REVENUES:
Net premiums earned									23,879	26,040	42,383
Net investment income									133,933	126,957	12,324
Net investment gains (losses), including impairments									4,416	(22,507)	31,538
Net gains (losses) on derivative contracts									3,958	(699)	127,630
Net realized gain on extinguishment of debt									0	0	81,272
Litigation recoveries									0	0	125,869
Other revenues									31,096	14,533	30,266
Total revenues									197,282	144,324	451,282
EXPENSES:
Loss and loss adjustment expenses (benefit)									(45,767)	(69,320)	(405,534)
Intangible amortization									30,508	24,736	43,925
General & administrative and other expenses									57,491	88,306	84,455
Interest expense									63,587	64,025	168,158
Total expenses									105,819	107,747	(108,996)
Pretax income									91,463	36,577	560,278
Provision for income taxes									18,485	8,394	2,914
Loss on disposal									(570,145)	0	0
Net income (loss) from discontinued operations									(497,167)	28,183	557,364
Gain on purchase of AMPS									0	0	1,131
Net income (loss) attributable to Ambac common shareholders									$ (497,167)	$ 28,183	$ 558,495