Schedule II (Condensed Balance Sheets) (Detail) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash and cash equivalents	$ 990	$ 633	$ 1,130	$ 803
Deferred income taxes, net	1,200
Total assets	21,724	26,873	32,279
Total liabilities	18,530	25,150
Preferred stock, par value $1 per share; authorized shares-10,000,000; issued and outstanding-none
Common stock, par value $1 per share; authorized shares-400,000,000; issued shares-277,405,039 and 274,896,162	277	275
Additional paid-in capital	3,076	3,072
Retained earnings	2,039	805
Accumulated other comprehensive income (loss), net of deferred tax of $26 and $134	56	(176)
Treasury stock, at cost-81,733,530 and 81,752,966 shares	(2,275)	(2,276)
Total shareholders' equity of MBIA Inc.	3,173	1,700
Total liabilities and equity	21,724	26,873
Preferred stock, par value	$ 1	$ 1
Preferred stock, authorized shares	10,000,000	10,000,000
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0
Common stock, par value	$ 1	$ 1
Common stock, authorized shares	400,000,000	400,000,000
Common stock, issued shares	277,405,039	274,896,162
Accumulated other comprehensive income (loss), deferred tax	21	105
Treasury stock, shares	81,733,530	81,752,966
Parent Company [Member]
Fixed-maturity securities held as available-for-sale, at fair value (amortized cost $825 and $1,989)	843	1,809
Fixed-maturity securities at fair value	13	96
Investments pledged as collateral, at fair value (amortized cost $510 and $623)	443	543
Short-term investments held as available-for-sale, at fair value (amortized cost $235 and $648)	236	643
Other investments	4	83
Total investments	1,539	3,174
Cash and cash equivalents	92	132	83	149
Investment in wholly-owned subsidiaries	4,127	3,410
Deferred income taxes, net	581	114
Other assets	183	137
Total assets	6,522	6,967
Investment agreements	893	1,523
Securities sold under agreements to repurchase	32	669
Long-term debt	723	900
Affiliate loans payable	1,681	1,738
Derivative liabilities		356
Other liabilities	20	81
Total liabilities	3,349	5,267
Preferred stock, par value $1 per share; authorized shares-10,000,000; issued and outstanding-none
Common stock, par value $1 per share; authorized shares-400,000,000; issued shares-277,405,039 and 274,896,162	277	275
Additional paid-in capital	3,076	3,072
Retained earnings	2,039	805
Accumulated other comprehensive income (loss), net of deferred tax of $26 and $134	56	(176)
Treasury stock, at cost-81,733,530 and 81,752,966 shares	(2,275)	(2,276)
Total shareholders' equity of MBIA Inc.	3,173	1,700
Total liabilities and equity	6,522	6,967
Fixed-maturity securities held as available-for-sale, amortized cost	825	1,989
Investments pledged as collateral, amortized cost	510	623
Short-term investments held as available-for-sale, amortized cost	235	648
Preferred stock, par value	$ 1	$ 1
Preferred stock, authorized shares	10,000,000	10,000,000
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0
Common stock, par value	$ 1	$ 1
Common stock, authorized shares	400,000,000	400,000,000
Common stock, issued shares	277,405,039	274,896,162
Accumulated other comprehensive income (loss), deferred tax	$ 26	$ 134
Treasury stock, shares	81,733,530	81,752,966