Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Detail) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
		Mar. 31, 2023	Mar. 31, 2022
Basic and diluted earnings per share:
Net income (loss) from continuing operations available to common shareholders - Basic		$ (83)	$ (73)
Net income (loss) from continuing operations available to common shareholders - Diluted		(83)	(73)
Income (loss) from discontinued operations, net of income taxes		(3)	0
Less: Net income (loss) from discontinued operations attributable to noncontrolling interests		7	0
Net income (loss) from discontinued operations attributable to MBIA Inc.		(10)	0
Net income (loss) attributable to MBIA Inc.		$ (93)	$ (73)
Basic weighted average shares	[1]	49,945,917	49,631,448
Diluted weighted average shares	[1]	49,945,917	49,631,448
Continuing operations - Basic		$ (1.67)	$ (1.48)
Continuing operations - Diluted		(1.67)	(1.48)
Discontinued operations - Basic		(0.19)	0
Discontinued operations - Diluted		(0.19)	0
Net income (loss) per share attributable to MBIA Inc. - basic		(1.86)	(1.48)
Net income (loss) per share attributable to MBIA Inc. - diluted		$ (1.86)	$ (1.48)
Potentially dilutive securities excluded from the calculation of diluted EPS because of antidilutive affect		4,900,000	5,100,000

[1] Includes 0.7 million and 0.9 million of participating securities that met the service condition and were eligible to receive nonforfeitable dividends or dividend equivalents for the three months ended March 31, 2023 and 2022, respectively.