Special Purpose Entities, Including Variable Interest Entities - Additional Information (Detail) (USD $)			3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013 Predecessor Ambac [Member]	Mar. 31, 2014 Asset-Backed Securities and Utility Obligations [Member]	Mar. 31, 2014 Sponsored Variable Interest Entities [Member] Transactions	Dec. 31, 2013 Sponsored Variable Interest Entities [Member]	Mar. 31, 2014 Variable Interest Entity, Primary Beneficiary [Member]	Mar. 31, 2014 Variable Interest Entities [Member]	Dec. 31, 2013 Variable Interest Entities [Member]	Mar. 31, 2014 Consolidated Entities [Member] Entity	Dec. 31, 2013 Consolidated Entities [Member] Entity
Variable Interest Entities [Line Items]
Secured Debt							$ 0
Securities fair value	236,674,000	240,150,000						236,674,000	240,150,000
Fair value of special purpose entities	13,122,000	13,384,000
Number of individual transactions with special purpose entities					15
Number of transactions outstanding with special purpose entities					3
Total principal amount of debt outstanding					461,355,000	461,355,000
Weighted average life				7 years 9 months 12 days
Average rating of assets held by sponsored special purpose entities				BBB
Claims on insurance policies issued to these entities			1,455,000
Number of consolidated Variable Interest Entities										18	18
Consolidated VIE assets	15,832,337,000	15,988,697,000
Consolidated VIE liabilities	$ 15,727,102,000	$ 15,872,770,000