Variable Interest Entities (Summary Of Nonconsolidated VIEs Assets And Liabilities) (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014		Dec. 31, 2013
Collateralized Debt Obligations [Member]
Variable Interest Entity [Line Items]
VIE Assets	$ 8,399		$ 12,565
Maximum Exposure to Loss	6,267		7,693
Investments	117	[1]	120	[1]
Premiums receivable	30	[2]	43	[2]
Insurance loss recoverable	0	[3]	0	[3]
Unearned premium revenue	25	[4]	37	[4]
Loss and loss adjustment expense reserves	8	[5]	21	[5]
Derivative liabilities	96	[6]	108	[6]
Residential Mortgage Backed Securities [Member]
Variable Interest Entity [Line Items]
VIE Assets	15,622		21,738
Maximum Exposure to Loss	8,274		9,251
Investments	9	[1]	10	[1]
Premiums receivable	48	[2]	53	[2]
Insurance loss recoverable	587	[3]	658	[3]
Unearned premium revenue	46	[4]	51	[4]
Loss and loss adjustment expense reserves	322	[5]	327	[5]
Derivative liabilities	5	[6]	5	[6]
Commercial Mortgage Backed Securities [Member]
Variable Interest Entity [Line Items]
VIE Assets	617		1,367
Maximum Exposure to Loss	322		447
Investments	0	[1]	0	[1]
Premiums receivable	1	[2]	1	[2]
Insurance loss recoverable	0	[3]	0	[3]
Unearned premium revenue	1	[4]	1	[4]
Loss and loss adjustment expense reserves	0	[5]	0	[5]
Derivative liabilities	0	[6]	0	[6]
Consumer Asset Backed [Member]
Variable Interest Entity [Line Items]
VIE Assets	6,372		7,830
Maximum Exposure to Loss	2,450		2,740
Investments	0	[1]	9	[1]
Premiums receivable	18	[2]	19	[2]
Insurance loss recoverable	0	[3]	0	[3]
Unearned premium revenue	16	[4]	19	[4]
Loss and loss adjustment expense reserves	10	[5]	13	[5]
Derivative liabilities	0	[6]	0	[6]
Corporate Asset Backed [Member]
Variable Interest Entity [Line Items]
VIE Assets	10,414		13,028
Maximum Exposure to Loss	6,414		7,248
Investments	1	[1]	2	[1]
Premiums receivable	62	[2]	80	[2]
Insurance loss recoverable	18	[3]	18	[3]
Unearned premium revenue	75	[4]	96	[4]
Loss and loss adjustment expense reserves	0	[5]	0	[5]
Derivative liabilities	0	[6]	0	[6]
Global Structured Finance [Member]
Variable Interest Entity [Line Items]
VIE Assets	41,424		56,528
Maximum Exposure to Loss	23,727		27,379
Investments	127	[1]	141	[1]
Premiums receivable	159	[2]	196	[2]
Insurance loss recoverable	605	[3]	676	[3]
Unearned premium revenue	163	[4]	204	[4]
Loss and loss adjustment expense reserves	340	[5]	361	[5]
Derivative liabilities	101	[6]	113	[6]
Global Public Finance [Member]
Variable Interest Entity [Line Items]
VIE Assets	56,176		52,317
Maximum Exposure to Loss	20,609		20,162
Investments	0	[1]	0	[1]
Premiums receivable	203	[2]	206	[2]
Insurance loss recoverable	0	[3]	0	[3]
Unearned premium revenue	243	[4]	248	[4]
Loss and loss adjustment expense reserves	5	[5]	5	[5]
Derivative liabilities	0	[6]	0	[6]
Total Insurance [Member]
Variable Interest Entity [Line Items]
VIE Assets	97,600	[7]	108,845
Maximum Exposure to Loss	44,336	[7]	47,541
Investments	127	[1],[7]	141	[1]
Premiums receivable	362	[2],[7]	402	[2]
Insurance loss recoverable	605	[3],[7]	676	[3]
Unearned premium revenue	406	[4],[7]	452	[4]
Loss and loss adjustment expense reserves	345	[5],[7]	366	[5]
Derivative liabilities	101	[6],[7]	113	[6]
Collateral Loan Obligations [Member]
Variable Interest Entity [Line Items]
VIE Assets	179
Trading Securities	$ 4

[1] Reported within "Investments" on MBIA's consolidated balance sheets.

[2] Reported within "Premiums receivable" on MBIA's consolidated balance sheets.

[3] Reported within "Insurance loss recoverable" on MBIA's consolidated balance sheets.

[4] Reported within "Unearned premium revenue" on MBIA's consolidated balance sheets.

[5] Reported within "Loss and loss adjustment expense reserves" on MBIA's consolidated balance sheets.

[6] Reported within "Derivative liabilities" on MBIA's consolidated balance sheets.

[7] In addition, the Company holds a $4 million variable interest in a non-insurance VIE that invested in loans that totaled $179 million.