| Document and Entity Information | Feb. 11, 2021 |
| Cover [Abstract] | |
| Entity Registrant Name | MBIA INC |
| Amendment Flag | false |
| Entity Central Index Key | 0000814585 |
| Document Type | 8-K |
| Document Period End Date | Feb. 11, 2021 |
| Entity Incorporation State Country Code | CT |
| Entity File Number | 001-9583 |
| Entity Tax Identification Number | 06-1185706 |
| Entity Address, Address Line One | 1 Manhattanville Road |
| Entity Address, Address Line Two | Suite 301 |
| Entity Address, City or Town | Purchase |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10577 |
| City Area Code | 914 |
| Local Phone Number | 273-4545 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, par value $1 per share |
| Trading Symbol | MBI |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
