Loss And Loss Adjustment Expense Reserves (Schedule Of Financial Guarantees And Related Claim Liability) (Detail) $ in Millions		12 Months Ended
		Dec. 31, 2015 USD ($) issue policy	Dec. 31, 2014 USD ($) issue policy
Loss And Loss Adjustment Expense Reserves [Line Items]
Number of policies | policy		411	315
Number of issues | issue	[1]	140	147
Remaining weighted average contract period (in years)		7 years 4 months 24 days	7 years 8 months 12 days
Principal	[2]	$ 11,160	$ 11,263
Interest	[2]	6,247	4,620
Total	[2]	17,407	15,883
Gross claim liability		797	850
Less: Gross potential recoveries		752	860
Discount, net	[3]	116	14
Net claim liability (recoverable)		(71)	(24)
Unearned premium revenue		$ 98	$ 167
Caution List Low [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Number of policies | policy		57	38
Number of issues | issue	[1]	12	18
Remaining weighted average contract period (in years)		7 years 7 months 6 days	7 years 2 months 12 days
Principal	[2]	$ 2,591	$ 1,757
Interest	[2]	2,733	696
Total	[2]	5,324	2,453
Gross claim liability		0	0
Less: Gross potential recoveries		0	0
Discount, net	[3]	0	0
Net claim liability (recoverable)		0	0
Unearned premium revenue		$ 8	$ 63
Caution List Medium [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Number of policies | policy		18	98
Number of issues | issue	[1]	6	7
Remaining weighted average contract period (in years)		6 years 8 months 12 days	12 years
Principal	[2]	$ 147	$ 1,372
Interest	[2]	57	819
Total	[2]	204	2,191
Gross claim liability		0	0
Less: Gross potential recoveries		0	0
Discount, net	[3]	0	0
Net claim liability (recoverable)		0	0
Unearned premium revenue		$ 2	$ 19
Caution List High [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Number of policies | policy		171	4
Number of issues | issue	[1]	5	3
Remaining weighted average contract period (in years)		9 years 7 months 6 days	10 years 1 month 6 days
Principal	[2]	$ 1,996	$ 133
Interest	[2]	1,038	68
Total	[2]	3,034	201
Gross claim liability		0	0
Less: Gross potential recoveries		0	0
Discount, net	[3]	0	0
Net claim liability (recoverable)		0	0
Unearned premium revenue		$ 33	$ 5
Classified List [Member]
Loss And Loss Adjustment Expense Reserves [Line Items]
Number of policies | policy		165	175
Number of issues | issue	[1]	117	119
Remaining weighted average contract period (in years)		6 years 8 months 12 days	7 years
Principal	[2]	$ 6,426	$ 8,001
Interest	[2]	2,419	3,037
Total	[2]	8,845	11,038
Gross claim liability		797	850
Less: Gross potential recoveries		752	860
Discount, net	[3]	116	14
Net claim liability (recoverable)		(71)	(24)
Unearned premium revenue		$ 55	$ 80

[1] An issue represents the aggregate of financial guarantee policies that share the same revenue source for purposes of making debt service payments.

[2] Represents contractual principal and interest payments due by the issuer of the obligations insured by MBIA.

[3] Represents discount related to Gross Claim Liability and Gross Potential Recoveries.