Consolidated Statement Of Changes In Shareholders' Equity (USD $) In Millions, except Share data	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Total Shareholders' Equity Of MBIA Inc. [Member]	Preferred Stock Of Subsidiary And Noncontrolling Interest [Member]
Beginning Balance at Dec. 31, 2011	$ 1,723	$ 275	$ 3,072	$ 805	$ (176)	$ (2,276)	$ 1,700	$ 23
Beginning Balance (in shares) at Dec. 31, 2011		274,896,162				(81,752,966)		1,315
Net income	598			598			598
Other comprehensive income (loss)	266				266		266
Share-based compensation net of tax of $0 (In Shares)		558,937				23,174
Share-based compensation net of tax of $0	1					1	1
Change in noncontrolling interest in subsidiary	(1)							(1)
Ending Balance at Sep. 30, 2012	$ 2,587	$ 275	$ 3,072	$ 1,403	$ 90	$ (2,275)	$ 2,565	$ 22
Ending Balance (in shares) at Sep. 30, 2012		275,455,099				(81,729,792)		1,315