XML 51 R40.htm IDEA: XBRL DOCUMENT
v3.20.2

Loss And Loss Adjustment Expense Reserves (Schedule Of Insurance Loss Recoverable) (Detail) - Insurance Loss Recoverable [Member] $ in Millions | 9 Months Ended
--- | ---
Sep. 30, 2020 USD ($)
Roll forward of Insurance Loss Recoverable [Line Items] |
Gross Reserve beginning balance, Insurance loss recoverable | $ 1,694
Collections for Cases | (35)
Accretion of Recoveries | 11
Changes in Discount Rates | 152
Changes in Assumptions | (21)
Other | (3)
Gross Reserve ending balance, Insurance loss recoverable | $ 1,798

X
- Definition Cash receipts related to recoveries of previously paid claims + References No definition available. + Details
Name: | mbi_CollectionsForCases
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- 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
Period Type: | instant

X
- Definition Insurance Loss Recoverable And Changes In Recoveries Of Unpaid Losses Accretion Of Recoveries + References No definition available. + Details
Name: | mbi_InsuranceLossRecoverableAndChangesInRecoveriesOfUnpaidLossesAccretionOfRecoveries
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Insurance Loss Recoverable And Changes In Recoveries Of Unpaid Losses Change In Assumptions + References No definition available. + Details
Name: | mbi_InsuranceLossRecoverableAndChangesInRecoveriesOfUnpaidLossesChangeInAssumptions
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Insurance Loss Recoverable And Changes In Recoveries Of Unpaid Losses Change In Discount Rate + References No definition available. + Details
Name: | mbi_InsuranceLossRecoverableAndChangesInRecoveriesOfUnpaidLossesChangeInDiscountRate
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Changes in the timing and amount of net collections on financial guarantee contracts. + References No definition available. + Details
Name: | mbi_InsuranceLossRecoverableAndChangesInRecoveriesOfUnpaidLossesOther
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Roll forward of Insurance Loss Recoverable [Line Items] + References No definition available. + Details
Name: | mbi_RollForwardOfInsuranceLossRecoverableLineItems
Namespace Prefix: | mbi_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | mbi_ClaimLiabilityAxis=mbi_InsuranceLossRecoverableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |