Financial Guarantee Insurance Contracts - Summary of Information Related to Policies Currently Included in Ambac's Loss Reserves or Subrogation Recoverable (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items]
Losses and loss expense reserve	$ 5,826,168	$ 5,968,712
Subrogation recoverable	(512,235)	(498,478)
Successor Ambac [Member]
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items]
Unpaid claims on policies allocated to segregated account	3,962,531	3,904,315
Losses and loss expense reserve	5,826,168	5,968,712
Losses and loss expense reserves included in subrogation recoverable	1,803,582	1,797,805
Subrogation recoverable	(512,235)	(498,478)
Subrogation recoveries included in subrogation recoverable	1,168,929	1,164,179
Liability for Claims	$ 5,313,933	$ 5,470,234