Derivative Instruments - Summary of Gross Fair Values of Individual Derivative Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	$ 81,911	$ 77,711
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	300,840	253,898
Successor Ambac [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	134,986	134,587
Gross Amounts of Recognized Liabilities, Derivative Liabilities	353,915	310,774
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	53,075	56,876
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	53,075	56,876
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	81,911	77,711
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	300,840	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	75,964	42,555
Net Amount, Derivative Assets	81,911	77,021
Net Amount, Derivative Liabilities	224,876	211,343
Successor Ambac [Member] | Variable Interest Entities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities, Derivative Liabilities	1,844,690	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	1,844,690	1,772,306
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities
Net Amount, Derivative Liabilities	1,844,690	1,772,306
Successor Ambac [Member] | Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	134,556	132,250
Gross Amounts of Recognized Liabilities, Derivative Liabilities	266,051	216,287
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	53,075	56,876
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	53,075	56,876
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	81,481	75,374
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	212,976	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	75,964	42,555
Net Amount, Derivative Assets	81,481	75,374
Net Amount, Derivative Liabilities	137,012	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	1,758,626	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	1,758,626	1,680,834
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities
Net Amount, Derivative Liabilities	1,758,626	1,680,834
Successor Ambac [Member] | Futures Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	430	2,337
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 Assets Presented in the Consolidated Balance Sheet, Derivative Assets	430	2,337
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Assets		690
Net Amount, Derivative Assets	430	1,647
Successor Ambac [Member] | Credit Derivatives [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities, Derivative Liabilities	87,715	94,322
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	87,715	94,322
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities
Net Amount, Derivative Liabilities	87,715	94,322
Successor Ambac [Member] | Other Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities, Derivative Liabilities	149	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	149	165
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities
Net Amount, Derivative Liabilities	149	165
Successor Ambac [Member] | Currency Swaps [Member] | Variable Interest Entities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities, Derivative Liabilities	86,064	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	86,064	91,472
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities
Net Amount, Derivative Liabilities	$ 86,064	$ 91,472