Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Detail) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023
Basic and diluted earnings per share:
Net Income (Loss) Available to Common Stockholders, Basic, Total		$ (87)	$ (83)
Income (loss) from discontinued operations, net of income taxes		1	(3)
Less: Net income (loss) from discontinued operations attributable to noncontrolling interests		0	7
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent, Total		1	(10)
Net income (loss)		$ (86)	$ (93)
Basic weighted average shares	[1]	46,820,922	49,945,917
Diluted weighted average shares	[1]	46,820,922	49,945,917
Continuing operations - Basic		$ (1.88)	$ (1.67)
Continuing operations - Diluted		(1.88)	(1.67)
Discontinued operations - Basic		0.04	(0.19)
Discontinued operations - Diluted		0.04	(0.19)
Net income (loss) per share attributable to MBIA Inc. - basic		(1.84)	(1.86)
Earnings Per Share, Diluted		$ (1.84)	$ (1.86)
Potentially dilutive securities excluded from the calculation of diluted EPS because of antidilutive affect		4,000,000	4,900,000

[1] Includes approximately 1 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, 2024 and 2023.