Financial Guarantee Insurance Contracts - Summary of Information Related to Policies Currently Included in Ambac's Loss Reserves or Subrogation Recoverable (Phantom) (Detail) - Successor [Member] - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items]
Loss Reserves Ceded To Reinsurers	$ 30,108	$ 44,059	$ 71,031	$ 100,355
Loss and loss expense reserves	4,327,938	4,088,106
Subrogation recoverable	(677,157)	(1,229,293)
Liability for Claims	3,650,781	2,858,813	3,386,012	$ 3,798,733
Ceded Loss And Loss Expenses Paid Not Yet Recovered	$ (1,404)	$ (60)	$ 4,974