Variable Interest Entities (Summary Of Nonconsolidated VIEs Assets And Liabilities) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Variable Interest Entity [Line Items]
Premiums receivable	$ 1,051		$ 1,228		$ 1,360
Derivative liabilities	1,200		2,900
Collateralized Debt Obligations [Member]
Variable Interest Entity [Line Items]
VIE Assets	12,565		16,925
Maximum Exposure to Loss	7,693		10,873
Investments	120	[1]	0	[1]
Premiums receivable	43	[2]	62	[2]
Insurance loss recoverable	0	[3]	5	[3]
Unearned premium revenue	37	[4]	55	[4]
Loss and loss adjustment expense reserves	21	[5]	37	[5]
Derivative liabilities	108	[6]	74	[6]
Residential Mortgage Backed Securities [Member]
Variable Interest Entity [Line Items]
VIE Assets	21,738		34,061
Maximum Exposure to Loss	9,251		13,075
Investments	10	[1]	11	[1]
Premiums receivable	53	[2]	77	[2]
Insurance loss recoverable	658	[3]	3,278	[3]
Unearned premium revenue	51	[4]	75	[4]
Loss and loss adjustment expense reserves	327	[5]	440	[5]
Derivative liabilities	5	[6]	4	[6]
Commercial Mortgage Backed Securities [Member]
Variable Interest Entity [Line Items]
VIE Assets	1,367		4,801
Maximum Exposure to Loss	447		2,432
Investments	0	[1]	0	[1]
Premiums receivable	1	[2]	2	[2]
Insurance loss recoverable	0	[3]	0	[3]
Unearned premium revenue	1	[4]	2	[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	7,830		5,820
Maximum Exposure to Loss	2,740		3,086
Investments	9	[1]	10	[1]
Premiums receivable	19	[2]	19	[2]
Insurance loss recoverable	0	[3]	0	[3]
Unearned premium revenue	19	[4]	19	[4]
Loss and loss adjustment expense reserves	13	[5]	21	[5]
Derivative liabilities	0	[6]	0	[6]
Corporate Asset Backed [Member]
Variable Interest Entity [Line Items]
VIE Assets	13,028		19,980
Maximum Exposure to Loss	7,248		9,981
Investments	2	[1]	0	[1]
Premiums receivable	80	[2]	123	[2]
Insurance loss recoverable	18	[3]	13	[3]
Unearned premium revenue	96	[4]	140	[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	56,528		81,587
Maximum Exposure to Loss	27,379		39,447
Investments	141	[1]	21	[1]
Premiums receivable	196	[2]	283	[2]
Insurance loss recoverable	676	[3]	3,296	[3]
Unearned premium revenue	204	[4]	291	[4]
Loss and loss adjustment expense reserves	361	[5]	498	[5]
Derivative liabilities	113	[6]	78	[6]
Global Public Finance [Member]
Variable Interest Entity [Line Items]
VIE Assets	52,317		39,259
Maximum Exposure to Loss	20,162		21,346
Investments	0	[1]	0	[1]
Premiums receivable	206	[2]	220	[2]
Insurance loss recoverable	0	[3]	0	[3]
Unearned premium revenue	248	[4]	267	[4]
Loss and loss adjustment expense reserves	5	[5]	4	[5]
Derivative liabilities	0	[6]	0	[6]
Total Insurance [Member]
Variable Interest Entity [Line Items]
VIE Assets	108,845		120,846
Maximum Exposure to Loss	47,541		60,793
Investments	141	[1]	21	[1]
Premiums receivable	402	[2]	503	[2]
Insurance loss recoverable	676	[3]	3,296	[3]
Unearned premium revenue	452	[4]	558	[4]
Loss and loss adjustment expense reserves	366	[5]	502	[5]
Derivative liabilities	$ 113	[6]	$ 78	[6]

[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.