Consolidated Statement Of Changes In Shareholders' Equity (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Beginning Balance			$ 1,723
Net income	581	137	591	(1,138)
Other comprehensive income (loss)	62	146	212	211
Change in noncontrolling interest in subsidiary			(1)
Ending Balance	2,525		2,525
Common Stock [Member]
Beginning Balance			275
Beginning Balance (in shares)			274,896,162
Share-based compensation net of tax of $6 (In Shares)			583,480
Ending Balance	275		275
Ending Balance (in shares)	275,479,642		275,479,642
Additional Paid-In Capital [Member]
Beginning Balance			3,072
Share-based compensation net of tax of $6			(1)
Ending Balance	3,071		3,071
Retained Earnings [Member]
Beginning Balance			805
Net income			591
Ending Balance	1,396		1,396
Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance			(176)
Other comprehensive income (loss)			212
Ending Balance	36		36
Treasury Stock [Member]
Beginning Balance			(2,276)
Beginning Balance (in shares)			(81,752,966)
Share-based compensation net of tax of $6 (In Shares)			20,692
Share-based compensation net of tax of $6			1
Ending Balance	(2,275)		(2,275)
Ending Balance (in shares)	(81,732,274)		(81,732,274)
Total Shareholders' Equity Of MBIA Inc. [Member]
Beginning Balance			1,700
Net income			591
Other comprehensive income (loss)			212
Ending Balance	2,503		2,503
Preferred Stock Of Subsidiary And Noncontrolling Interest [Member]
Beginning Balance			23
Beginning Balance (in shares)			1,315
Change in noncontrolling interest in subsidiary			(1)
Ending Balance	$ 22		$ 22
Ending Balance (in shares)	1,315		1,315