v3.26.1
Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Detail) - USD ($)
$ / shares in Units, $ in Millions
3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Basic and diluted earnings per share:    
Net income (loss) from continuing operations available to common shareholders $ (41) $ (62)
Less: Net income (loss) from continuing operations attributable to noncontrolling interests (2) 0
Net income (loss) from continuing operations attributable to MBIA Inc. (41) (62)
Net income (loss) from discontinued operations attributable to MBIA Inc. (1) 0
Net income (loss) attributable to MBIA Inc. $ (40) $ (62)
Basic weighted average shares [1] 49,796,216 48,354,307
Diluted weighted average shares [1] 49,796,216 48,354,307
Continuing operations - Basic $ (0.79) $ (1.28)
Continuing operations - Diluted (0.79) (1.28)
Discontinued operations - Basic (0.01) 0
Discontinued operations - Diluted (0.01) (0)
Net income (loss) per share attributable to MBIA Inc. - basic (0.8) (1.28)
Net income (loss) per share attributable to MBIA Inc. - diluted $ (0.8) $ (1.28)
Potentially dilutive securities excluded from the calculation of diluted EPS because of antidilutive affect 800,000 900,000
MBIA Inc. [Member]    
Basic and diluted earnings per share:    
Net income (loss) from continuing operations attributable to MBIA Inc. $ (39) $ (62)
Net income (loss) from discontinued operations attributable to MBIA Inc. $ (1) $ 0
[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, 2026 and 2025.