Derivative Instruments - Summary of Gross Fair Values of Individual Derivative Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	$ 89,680	$ 77,711
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	342,273	253,898
Successor Ambac [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	141,002	134,587
Gross Amounts of Recognized Liabilities, Derivative Liabilities	393,595	310,774
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	51,322	56,876
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	51,322	56,876
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	89,680	77,711
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	342,273	253,898
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Assets		690
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities	103,157	42,555
Net Amount, Derivative Assets	89,680	77,021
Net Amount, Derivative Liabilities	239,116	211,343
Successor Ambac [Member] | Variable Interest Entities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities, Derivative Liabilities	1,927,460	1,772,306
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	1,927,460	1,772,306
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities
Net Amount, Derivative Liabilities	1,927,460	1,772,306
Successor Ambac [Member] | Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	140,683	132,250
Gross Amounts of Recognized Liabilities, Derivative Liabilities	303,317	216,287
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	51,322	56,876
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	51,322	56,876
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	89,361	75,374
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	251,995	159,411
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Assets
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities	102,977	42,555
Net Amount, Derivative Assets	89,361	75,374
Net Amount, Derivative Liabilities	149,018	116,856
Successor Ambac [Member] | Interest Rate Swaps [Member] | Variable Interest Entities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities, Derivative Liabilities	1,840,399	1,680,834
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	1,840,399	1,680,834
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities
Net Amount, Derivative Liabilities	1,840,399	1,680,834
Successor Ambac [Member] | Futures Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets		2,337
Gross Amounts of Recognized Liabilities, Derivative Liabilities	180
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	0
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets		2,337
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	180
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Assets		690
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities	180
Net Amount, Derivative Assets		1,647
Net Amount, Derivative Liabilities	0
Successor Ambac [Member] | Credit Derivatives [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	319
Gross Amounts of Recognized Liabilities, Derivative Liabilities	89,970	94,322
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	0
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	319
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	89,970	94,322
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Assets
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities
Net Amount, Derivative Assets	319
Net Amount, Derivative Liabilities	89,970	94,322
Successor Ambac [Member] | Other Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities, Derivative Liabilities	128	165
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	128	165
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities
Net Amount, Derivative Liabilities	128	165
Successor Ambac [Member] | Currency Swaps [Member] | Variable Interest Entities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities, Derivative Liabilities	87,061	91,472
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	87,061	91,472
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities
Net Amount, Derivative Liabilities	$ 87,061	$ 91,472