Fair Value Of Financial Instruments (Fair Value Hierarchy Table Presents The Company's Assets And Liabilities At Fair Value Not Recorded On The Company's Consolidated Balance Sheet) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Investments held-to-maturity, fair value	$ 2,651		$ 2,674
Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Inputs Level 1 [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Other investments	0		0
Accrued investment income	0	[1]	0	[1]
Receivable for investments sold	0	[1]	0	[1]
Net cash collateral pledged	24	[1]	66	[1]
Total assets	24		66
Investment agreements	0		0
Medium-term notes	0		0
Securities Loaned Or Sold Under Agreements To Repurchase	0		0
Long-term debt	0		0
Payable for investments purchased	0	[2]	0	[2]
Secured loan	0
Total liabilities	0		0
Gross	0		0
Ceded	0		0
Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Inputs Level 1 [Member] | Variable Interest Entity Primary Beneficiary [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Variable interest entity notes	0		0
Investments held-to-maturity, fair value	0		0
Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Inputs Level 2 [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Other investments	0		0
Accrued investment income	52	[1]	43	[1]
Receivable for investments sold	22	[1]	17	[1]
Net cash collateral pledged	0	[1]	0	[1]
Total assets	74		60
Investment agreements	0		0
Medium-term notes	0		0
Securities Loaned Or Sold Under Agreements To Repurchase	0		0
Long-term debt	1,412		711
Payable for investments purchased	31	[2]	50	[2]
Secured loan	0
Total liabilities	1,443		761
Gross	0		0
Ceded	0		0
Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Inputs Level 2 [Member] | Variable Interest Entity Primary Beneficiary [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Variable interest entity notes	0		0
Investments held-to-maturity, fair value	0		0
Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Inputs Level 3 [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Other investments	4		9
Accrued investment income	0	[1]	0	[1]
Receivable for investments sold	0	[1]	0	[1]
Net cash collateral pledged	0	[1]	0	[1]
Total assets	2,655		2,683
Investment agreements	814		1,175
Medium-term notes	927		860
Securities Loaned Or Sold Under Agreements To Repurchase	0		0
Long-term debt	0		0
Payable for investments purchased	0	[2]	0	[2]
Secured loan	0
Total liabilities	4,492		5,182
Gross	2,843		650
Ceded	71		97
Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Inputs Level 3 [Member] | Variable Interest Entity Primary Beneficiary [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Variable interest entity notes	2,751		3,147
Investments held-to-maturity, fair value	2,651		2,674
Carrying Reported Amount Fair Value Disclosure [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Other investments	5		9
Accrued investment income	52	[1]	43	[1]
Receivable for investments sold	22	[1]	17	[1]
Net cash collateral pledged	24	[1]	66	[1]
Total assets	2,904		2,964
Investment agreements	700		944
Medium-term notes	1,224		1,433
Securities Loaned Or Sold Under Agreements To Repurchase	0		0
Long-term debt	1,702		1,732
Payable for investments purchased	31	[2]	50	[2]
Secured loan	0
Total liabilities	6,587		7,624
Gross	2,388		143
Ceded	76		91
Carrying Reported Amount Fair Value Disclosure [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Variable Interest Entity Primary Beneficiary [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Variable interest entity notes	2,930		3,465
Investments held-to-maturity, fair value	2,801		2,829
Fair Value [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Other investments	4		9
Accrued investment income	52	[1]	43	[1]
Receivable for investments sold	22	[1]	17	[1]
Net cash collateral pledged	24	[1]	66	[1]
Total assets	2,753		2,809
Investment agreements	814		1,175
Medium-term notes	927		860
Securities Loaned Or Sold Under Agreements To Repurchase	0		0
Long-term debt	1,412		711
Payable for investments purchased	31	[2]	50	[2]
Secured loan	0
Total liabilities	5,935		5,943
Gross	2,843		650
Ceded	71		97
Fair Value [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Variable Interest Entity Primary Beneficiary [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Variable interest entity notes	2,751		3,147
Investments held-to-maturity, fair value	$ 2,651		$ 2,674

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

[2] Reported within "Other liabilities" on MBIA's consolidated balance sheets.