Derivative Instruments - Summary of Notional for VIE Derivatives Outstanding (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule Of Loans And Allowance For Loan By Class Individually And Collectively Evaluated For Impairment [Line Items]
Derivative products, Notional Amount	$ 2,202,760	$ 2,776,103
Derivative products, Notional Amount	89,651	94,322
Successor Ambac [Member]
Schedule Of Loans And Allowance For Loan By Class Individually And Collectively Evaluated For Impairment [Line Items]
Derivative products, Notional Amount	2,202,760	2,776,103
Variable Interest Entity, Primary Beneficiary [Member] | Successor Ambac [Member] | Interest Rate Swaps [Member]
Schedule Of Loans And Allowance For Loan By Class Individually And Collectively Evaluated For Impairment [Line Items]
Derivative products, Notional Amount	1,877,383	1,818,118
Variable Interest Entity, Primary Beneficiary [Member] | Successor Ambac [Member] | Interest Rate Swaps-Pay-Fixed/Receive-Variable [Member]
Schedule Of Loans And Allowance For Loan By Class Individually And Collectively Evaluated For Impairment [Line Items]
Derivative products, Notional Amount	3,459,937	3,350,714
Variable Interest Entity, Primary Beneficiary [Member] | Successor Ambac [Member] | Currency Swaps [Member]
Schedule Of Loans And Allowance For Loan By Class Individually And Collectively Evaluated For Impairment [Line Items]
Derivative products, Notional Amount	795,429	770,319
Variable Interest Entity, Primary Beneficiary [Member] | Successor Ambac [Member] | Credit Derivatives [Member]
Schedule Of Loans And Allowance For Loan By Class Individually And Collectively Evaluated For Impairment [Line Items]
Derivative products, Notional Amount	$ 20,063	$ 20,130