Fair Value Of Financial Instruments (Gains And Losses On Fair Value Option Included In The Company's Consolidated Statements Of Operations) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014	Jun. 30, 2013
Accounts Notes And Loans Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	$ 61		$ (6)		$ 6	$ 57
Non Variable Interest Entity [Member]
Accounts Notes And Loans Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	61		(6)		6	57
Variable Interest Entity [Member]
Accounts Notes And Loans Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	23		78		26	111
Loan Repurchase Commitments [Member] | Variable Interest Entity [Member]
Accounts Notes And Loans Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	0	[1]	50	[1]	5	139
Investments Carried At Fair Value [Member] | Non Variable Interest Entity [Member]
Accounts Notes And Loans Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	1	[2]	2	[2]	2	6
Fixed Maturity Securities Held At Fair Value - VIE [Member] | Variable Interest Entity [Member]
Accounts Notes And Loans Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	(30)	[1]	(16)	[1]	(68)	2
Residential Mortgage Loans [Member] | Variable Interest Entity [Member]
Accounts Notes And Loans Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	(17)	[1]	145	[1]	(73)	71
Other Loans [Member] | Variable Interest Entity [Member]
Accounts Notes And Loans Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	0	[1]	0	[1]	0	13
Other Assets [Member] | Variable Interest Entity [Member]
Accounts Notes And Loans Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	0		0		0	0
Medium Term Notes [Member] | Non Variable Interest Entity [Member]
Accounts Notes And Loans Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	(2)	[2]	(7)	[2]	(14)	(23)
Variable Interest Entity Notes [Member] | Variable Interest Entity [Member]
Accounts Notes And Loans Receivable [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	$ 48		$ (160)		$ 169	$ (79)

[1] Reported within "Net gains (losses) of financial instruments at fair value and foreign exchange-VIE" on MBIA's consolidated statements of operations.

[2] Reported within "Net gains (losses) of financial instruments at fair value and foreign exchange" on MBIA's consolidated statements of operations.