Debt (Narrative) (Detail) (USD $)	0 Months Ended					9 Months Ended		0 Months Ended		0 Months Ended	3 Months Ended	9 Months Ended	0 Months Ended					9 Months Ended
	May 06, 2013 MBIA Inc Senior Notes [Member]	Sep. 30, 2013 MBIA Inc Senior Notes [Member]	Dec. 31, 2012 MBIA Inc Senior Notes [Member]	Sep. 30, 2013 MBIA Corp Surplus Notes [Member]	Dec. 31, 2012 MBIA Corp Surplus Notes [Member]	Sep. 30, 2013 Medium Term Notes [Member] Conduits [Member]	Sep. 30, 2013 Medium Term Notes [Member] Global Funding Limited [Member]	May 06, 2013 Bank Of America [Member]	Sep. 30, 2013 Mbia Inc [Member]	May 06, 2013 Blue Ridge [Member]	Sep. 30, 2013 Blue Ridge [Member]	Sep. 30, 2013 Blue Ridge [Member]	May 06, 2013 Blue Ridge [Member] Libor Rate Loans [Member] Applicable Margin [Member]	May 06, 2013 Blue Ridge [Member] Base Rate Loans [Member] Applicable Margin [Member]	May 06, 2013 Blue Ridge [Member] Base Rate Loans [Member] Federal Funds Rate Margin [Member]	May 06, 2013 Blue Ridge [Member] Base Rate Loans [Member] Adjusted Libor Rate Margin [Member]	May 06, 2013 Maximum [Member] Blue Ridge [Member]	Sep. 30, 2013 Maximum [Member] Blue Ridge [Member]	May 06, 2013 Minimum [Member] Blue Ridge [Member]	May 06, 2013 Fair Value [Member] Blue Ridge [Member]
Debt Instrument [Line Items]
14% Surplus Notes due 2033				$ 940,000,000	$ 940,000,000
Accrued interest		10,000,000	9,000,000	143,000,000	61,000,000
MBIA debt coupon rate				14.00%					5.70%
Long-term debt		584,000,000	723,000,000
Amount received on litigation settlement	136,000,000							1,700,000,000
Par value redeemed						486,000,000	80,000,000
Weighted average percent of par						100.00%	92.00%
Line of credit maximum amount										500,000,000
Line of credit amount outstanding											50,000,000	50,000,000
Line of credit interest rate											7.76%		7.50%	6.50%	0.50%	1.00%
General corporate purposes limit																	50,000,000
Liquidity requirements period										0 years 0 months 30 days
Equity interest collateral pledged percentage										65.00%
Secured line of credit collateral																			1,000,000,000	2,500,000,000
Line of credit commitment fee percentage										2.00%
Line of credit interest and commitment fee												4,000,000
Line of credit term										3 years
Putback recoveries collateral percentage										100.00%
Other prepayment collateral percentage after year one to year two										50.00%
Other prepayment collateral percentage after year two to year three										100.00%
Disposal of assets collateral percentage										100.00%
Disposal of assets maximum collateral																	1,000,000
Liquidity borrowings repayment period										0 years 0 months 30 days
Minimum statutory capital required																			750,000,000
Remediation efforts maximum amount																		260,000,000
Remediation efforts loans outstanding maximum amount																	200,000,000
Remediation efforts statutory capital reduction maximum																	$ 100,000,000