Insurance in Force (Narrative) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Guarantor Obligations [Line Items]
Transactions guaranteed by MBIA on behalf of various investment management service affiliates	$ 2,600,000,000	$ 3,500,000,000
Guarantees of derivative contracts, maturity range, minimum (Years)	1 year 0 months 0 days
Guarantees of derivative contracts, maturity range, maximum (Years)	68 years 0 months 0 days
Derivative Liabilities	246,000,000	1,200,000,000
Amount available under these letters of credit and trust arrangements	34,000,000
Aggregate amount of insurance in force ceded to reinsurers	11,100,000,000	12,700,000,000
Aggregate amount of insured par outstanding ceded to reinsurers	6,087,000,000	7,100,000,000
Recoveries received on claims for financial guarantee policies under reinsurance contracts	(5,000,000)	4,000,000	4,000,000
Ceding commissions from reinsurance	2,000,000	2,000,000	3,000,000
Guarantees Of Derivative Contracts [Member]
Guarantor Obligations [Line Items]
Guarantee Obligations Maximum Exposure	$ 10,100,000,000
Minimum [Member]
Guarantor Obligations [Line Items]
Insurance in force, expected maturity range, years	1 year 0 months 0 days
Minimum [Member] | Investment Agreement Contracts and MTNs [Member]
Guarantor Obligations [Line Items]
Future guarantee payments, maturity range, (years)	1 year 0 months 0 days
Maximum [Member]
Guarantor Obligations [Line Items]
Insurance in force, expected maturity range, years	43 years 0 months 0 days
Maximum [Member] | Investment Agreement Contracts and MTNs [Member]
Guarantor Obligations [Line Items]
Future guarantee payments, maturity range, (years)	27 years 0 months 0 days