Special Purpose Entities, Including Variable Interest Entities - Summary of Carrying Amount of Assets, Liabilities and Maximum Exposure to Loss of Ambac's Variable Interests in Non-Consolidated Variable Interest Entities (Detail) (Variable Interest Entity [Member], Successor Ambac [Member], USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Variable Interest Entities [Line Items]
Maximum Exposure To Loss	$ 67,890,086	$ 74,067,088
Insurance Assets	1,623,465	1,728,422
Insurance Liabilities	6,600,331	6,662,385
Derivative Liabilities	75,860	81,432
Global Structured Finance [Member]
Variable Interest Entities [Line Items]
Maximum Exposure To Loss	34,182,212	38,334,230
Insurance Assets	1,124,770	1,196,903
Insurance Liabilities	6,028,597	6,058,046
Derivative Liabilities	45,165	54,320
Global Public Finance [Member]
Variable Interest Entities [Line Items]
Maximum Exposure To Loss	33,707,874	35,732,858
Insurance Assets	498,695	531,519
Insurance Liabilities	571,734	604,339
Derivative Liabilities	30,695	27,112
Collateralized Debt Obligations [Member] | Global Structured Finance [Member]
Variable Interest Entities [Line Items]
Maximum Exposure To Loss	1,503,895	2,092,072
Insurance Assets	1,710	3,867
Insurance Liabilities	5,111	7,119
Derivative Liabilities	5,758	10,092
Residential Mortgage-Backed Securities [Member] | Global Structured Finance [Member]
Variable Interest Entities [Line Items]
Maximum Exposure To Loss	17,825,150	19,231,335
Insurance Assets	553,022	581,498
Insurance Liabilities	3,958,533	3,890,937
Derivative Liabilities
Other Consumer Asset-Backed [Member] | Global Structured Finance [Member]
Variable Interest Entities [Line Items]
Maximum Exposure To Loss	5,256,079	5,425,583
Insurance Assets	67,384	68,511
Insurance Liabilities	913,978	992,177
Derivative Liabilities	0	0
Other Commercial Asset-Backed [Member] | Global Structured Finance [Member]
Variable Interest Entities [Line Items]
Maximum Exposure To Loss	5,339,867	7,237,953
Insurance Assets	400,644	429,559
Insurance Liabilities	524,978	559,600
Derivative Liabilities	35,891	39,916
Other [Member] | Global Structured Finance [Member]
Variable Interest Entities [Line Items]
Maximum Exposure To Loss	4,257,221	4,347,287
Insurance Assets	102,010	113,468
Insurance Liabilities	625,997	608,213
Derivative Liabilities	$ 3,516	$ 4,312