Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Detail) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Basic and diluted earnings per share:
Net Income (Loss) Available to Common Stockholders, Basic, Total		$ (484)	$ (149)	$ (445)
Income (loss) from discontinued operations, net of income taxes		(3)	(54)	0
Less: Net income (loss) from discontinued operations attributable to noncontrolling interests		4	(8)	0
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent, Total		(7)	(46)	0
Net income (loss)		$ (491)	$ (195)	$ (445)
Basic weighted average shares	[1]	48,207,574	49,803,739	49,472,281
Diluted weighted average shares	[1]	48,207,574	49,803,739	49,472,281
Continuing operations - Basic		$ (10.03)	$ (3)	$ (8.99)
Continuing operations - Diluted		(10.03)	(3)	(8.99)
Discontinued operations - Basic		(0.15)	(0.92)	0
Discontinued operations - Diluted		(0.15)	(0.92)	0
Net income (loss) per share attributable to MBIA Inc. - basic		(10.18)	(3.92)	(8.99)
Earnings Per Share, Diluted		$ (10.18)	$ (3.92)	$ (8.99)
Potentially dilutive securities excluded from the calculation of diluted EPS because of antidilutive affect		4,300,000	5,000,000	5,100,000

[1] Includes 0.6 million, 0.8 million and 0.9 million of participating securities that met the service condition and were eligible to receive nonforfeitable dividends or dividend equivalents for each of the years ended December 31, 2023, 2022 and 2021 respectively.