Consolidated Statements 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, 2012	$ 3,194	$ 277	$ 3,076	$ 2,039	$ 56	$ (2,275)	$ 3,173	$ 21
Beginning Balance (in shares) at Dec. 31, 2012		277,405,039				(81,733,530)		1,315
Net income	164			164			164
Other comprehensive income (loss)	(47)				(47)		(47)
Share-based compensation, net of tax (in shares)		388,657				(3,102,480)
Share-based compensation, net of tax	(2)	1	31			(34)	(2)
Ending Balance at Mar. 31, 2013	$ 3,309	$ 278	$ 3,107	$ 2,203	$ 9	$ (2,309)	$ 3,288	$ 21
Ending Balance (in shares) at Mar. 31, 2013		277,793,696				(84,836,010)		1,315