Financial Guarantee Insurance Contracts - Summary of Loss Reserve Roll-Forward, Net of Subrogation Recoverable and Reinsurance (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014 Successor Ambac [Member]	Mar. 31, 2013 Predecessor Ambac [Member]
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Beginning loss and loss expense reserves, net of subrogation recoverable, gross of reinsurance	$ 5,470,234	$ 6,122,140
Less reinsurance on loss and loss expense reserves	122,357	147,409
Beginning balance of loss and loss expense reserves, net of subrogation recoverable and reinsurance	5,347,877	5,974,731
Current year:
Establishment of new loss and loss expense reserves, gross of RMBS subrogation and net of reinsurance	151	4,083
Claim and loss expense payments, net of subrogation and reinsurance	0	(58)
Establishment of RMBS subrogation recoveries, net of reinsurance	0	(188)
Total current year	151	3,837
Prior years:
Change in previously established loss and loss expense reserves, gross of RMBS subrogation and net of reinsurance	(117,692)	(129,090)
Claim and loss expense (payments)recoveries, net of subrogation and reinsurance	(9,375)	12,365
Change in previously established RMBS subrogation recoveries, net of reinsurance	(18,331)	34,617
Total prior years	(145,398)	(82,108)
Net change in loss and loss expense reserves	(145,247)	(78,271)
Ending loss and loss expense reserves, net of subrogation recoverable and reinsurance	5,202,630	5,896,460
Add reinsurance on loss and loss expense reserves	111,303	148,749
Ending loss and loss expense reserves, net of subrogation recoverable, gross of reinsurance	$ 5,313,933	$ 6,045,209