Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 22, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Central Index Key	0000814585
Current Fiscal Year End Date	--12-31
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2020
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Trading Symbol	MBI
Entity Registrant Name	MBIA INC
Entity Filer Category	Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Public Float			$ 404,974,161
Entity Common Stock, Shares Outstanding		53,726,305
Title of 12(b) Security	Common Stock
Security Exchange Name	NYSE
Entity File Number	1-9583
Entity Tax Identification Number	06-1185706
Entity Address, Address Line One	1 Manhattanville Road, Suite 301
Entity Address, City or Town	Purchase
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10577
Entity Incorporation, State or Country Code	CT
City Area Code	914
Local Phone Number	273-4545
ICFR Auditor Attestation Flag	true