Variable Interest Entities (Summary Of Nonconsolidated VIEs Assets And Liabilities) (Detail) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Variable Interest Entity [Line Items]
Premiums receivable		$ 792	$ 875	$ 1,051
Insurance loss recoverable		577	533	$ 694
Derivative liabilities		88	246
Global Structured Finance [Member]
Variable Interest Entity [Line Items]
VIE Assets		28,311	35,940
Maximum Exposure to Loss		14,495	19,958
Investments	[1]	74	119
Premiums receivable	[2]	80	123
Insurance loss recoverable	[3]	418	524
Unearned premium revenue	[4]	78	121
Loss and loss adjustment expense reserves	[5]	418	389
Derivative liabilities	[6]	6	102
Global Structured Finance [Member] | Collateralized Debt Obligations [Member]
Variable Interest Entity [Line Items]
VIE Assets		5,712	8,613
Maximum Exposure to Loss		3,046	5,623
Investments	[1]	51	110
Premiums receivable	[2]	9	24
Unearned premium revenue	[4]	6	20
Loss and loss adjustment expense reserves	[5]	108	70
Derivative liabilities	[6]	6	102
Global Structured Finance [Member] | Residential Mortgage Backed Securities [Member]
Variable Interest Entity [Line Items]
VIE Assets		11,524	14,136
Maximum Exposure to Loss		6,072	7,459
Investments	[1]	23	9
Premiums receivable	[2]	31	41
Insurance loss recoverable	[3]	416	518
Unearned premium revenue	[4]	30	39
Loss and loss adjustment expense reserves	[5]	306	307
Global Structured Finance [Member] | Commercial Mortgage Backed Securities [Member]
Variable Interest Entity [Line Items]
VIE Assets		319	571
Maximum Exposure to Loss		219	279
Premiums receivable	[2]	1	1
Unearned premium revenue	[4]	1	1
Global Structured Finance [Member] | Consumer Asset Backed [Member]
Variable Interest Entity [Line Items]
VIE Assets		5,538	6,008
Maximum Exposure to Loss		1,712	1,989
Premiums receivable	[2]	13	16
Unearned premium revenue	[4]	11	14
Loss and loss adjustment expense reserves	[5]	4	12
Global Structured Finance [Member] | Corporate Asset Backed [Member]
Variable Interest Entity [Line Items]
VIE Assets		5,218	6,612
Maximum Exposure to Loss		3,446	4,608
Premiums receivable	[2]	26	41
Insurance loss recoverable	[3]	2	6
Unearned premium revenue	[4]	30	47
Global Public Finance [Member]
Variable Interest Entity [Line Items]
VIE Assets		44,162	49,686
Maximum Exposure to Loss		14,579	16,698
Premiums receivable	[2]	160	179
Unearned premium revenue	[4]	186	211
Total Insurance [Member]
Variable Interest Entity [Line Items]
VIE Assets		72,473	85,626
Maximum Exposure to Loss		29,074	36,656
Investments	[1]	74	119
Premiums receivable	[2]	240	302
Insurance loss recoverable	[3]	418	524
Unearned premium revenue	[4]	264	332
Loss and loss adjustment expense reserves	[5]	418	389
Derivative liabilities	[6]	$ 6	$ 102

[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.