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Loss and Loss Adjustment Expense Reserves (Schedule of Insurance Loss Recoverable) (Detail) - Insurance Loss Recoverable [Member] - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2023 | Dec. 31, 2022
Roll forward of Insurance Loss Recoverable [Line Items] |  |
Gross Reserve beginning balance, Insurance loss recoverable | $ 137 | $ 1,296
Collections for Cases | (8) | (1,608)
Accretion of Recoveries | 6 | 7
Changes in Discount Rates | 0 | (22)
Changes in Assumptions | 48 | 464
Gross Reserve ending balance, Insurance loss recoverable | $ 183 | $ 137

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- Definition Cash receipts related to recoveries of previously paid claims + References No definition available. + Details
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- Definition Carrying amount as of the balance sheet date of paid insurance policy claims and LAE expense expected to be recovered. + References No definition available. + Details
Name: | mbi_InsuranceLossRecoverable
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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- Definition Insurance Loss Recoverable And Changes In Recoveries Of Unpaid Losses Accretion Of Recoveries + References No definition available. + Details
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- Definition Insurance Loss Recoverable And Changes In Recoveries Of Unpaid Losses Change In Assumptions + References No definition available. + Details
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- Definition Insurance Loss Recoverable And Changes In Recoveries Of Unpaid Losses Change In Discount Rate + References No definition available. + Details
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- Definition Roll forward of Insurance Loss Recoverable [Line Items] + References No definition available. + Details
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Balance Type: | na
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- Details
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Period Type: |