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	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Apr. 30, 2013
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items]
Loss and loss expense reserves	$ 6,072,323	$ 5,968,712
Subrogation recoverable	(484,152)	(498,478)
Successor Ambac [Member]
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items]
Liability for Claims	$ 5,588,171	$ 5,470,234	$ 5,541,562	$ 5,572,672