Background and Business Description - Additional Information (Detail) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2014 Rate	Dec. 31, 2010 Ambac Assurance [Member]	Jun. 30, 2014 Ambac Assurance [Member]	Jun. 30, 2014 Ambac Assurance [Member] Minimum [Member]
Background And Basis Of Presentation [Line Items]
Net par exposure for policies allocated to the Segregated Account			$ 20,898,745,000
Issuance of secured note to segregated account		2,000,000,000
Secured note maturity year		2050
Interest on the secured note accrues		4.50%
Available secured notes including capitalized interest			0
Minimum surplus amount				100,000,000
Policyholders surplus			$ 945,661,000
Accrued rate of interest on outstanding policy obligations (percent)	5.10%
Payment of permitted policy claim (percent)	25.00%
Future payment of permitted policy claim (percent)	45.00%
Future unpaid permitted policy claims (percent)	55.00%
Equalizing payment on unpaid permitted policy claim (percent)	26.67%