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Fair Value Of Financial Instruments (Changes In Level 3 Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Detail) - Fair Value Inputs Level 3 [Member] - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019
Accounts Notes And Loans Receivable [Line Items] |  |  |  |  |  |  |  |  |
Beginning balance, fair value assets |  | $ 638 |  | $ 669 |  | $ 649 |  | $ 637 |
Total gains/(losses) included in earnings, assets |  | 35 |  | 5 |  | 27 |  | 47 |
Unrealized gains/(losses) included in OCI, assets |  | 0 |  | 0 |  | 0 | [1] | 0 |
Purchases, assets |  | 0 |  | 0 |  | 0 |  | 0 |
Issuances, assets |  | 0 |  | 0 |  | 0 |  | 0 |
Settlements, assets |  | (4) |  | (9) |  | (7) |  | (19) |
Sales, assets |  | 0 |  | (49) |  | 0 |  | (49) |
Transfers into level 3, assets |  | 0 |  | 0 | [2] | 0 |  | 0 | [2]
Transfers out of level 3, assets |  | 0 |  | (3) | [2] | 0 |  | (3) | [2]
Ending balance, fair value assets |  | 669 |  | 613 |  | 669 |  | 613 |
Change in unrealized gains/(losses) for the period included in earnings for assets still held, assets |  | 33 |  | 4 |  | 26 |  | 43 |
Change in unrealized gains/(losses) for the period included in OCI for Liabilities still held | [1] | 0 |  |  |  | 0 |  |  |
Beginning balance, fair value liabilities |  | 424 |  | 532 |  | 500 |  | 513 |
Total gains/(losses) included in earnings, liabilities |  | 15 |  | 16 |  | (4) |  | 52 |
Unrealized gains/(losses) included in OCI, liabilities |  | (4) |  | 9 |  | (51) | [3] | (1) |
Purchases, liabilities |  | 0 |  | 0 |  | 0 |  | 0 |
Issuances, liabilities |  | 0 |  | 0 |  | 0 |  | 4 |
Settlements, liabilities |  | (3) |  | (8) |  | (13) |  | (19) |
Sales, liabilities |  | 0 |  | (60) |  | 0 |  | (60) |
Transfers into Level 3, liabilities |  | 0 |  | 0 | [2] | 0 |  | 0 | [2]
Transfers out of Level 3, liabilities |  | 0 |  | 0 | [2] | 0 |  | 0 | [2]
Ending balance, fair value liabilities |  | 432 |  | 489 |  | 432 |  | 489 |
Change in unrealized gains/(losses) for the period included in earnings for liabilities still held, liabilities |  | 14 |  | 17 |  | (7) |  | 43 |
Change in Unrealized (Gains)/ Losses for the Period Included in OCI for Liabilities still held |  | (4) | [4] |  |  | (50) | [3] |  |
Residential Prime Financing Receivable [Member] | Variable Interest Entity Primary Beneficiary [Member] |  |  |  |  |  |  |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |  |  |  |  |  |  |
Beginning balance, fair value assets |  | 98 |  | 206 |  | 136 |  | 172 |
Total gains/(losses) included in earnings, assets |  | 22 |  | 1 |  | (13) |  | 43 |
Unrealized gains/(losses) included in OCI, assets |  | 0 |  | 0 |  | 0 | [1] | 0 |
Purchases, assets |  | 0 |  | 0 |  | 0 |  | 0 |
Issuances, assets |  | 0 |  | 0 |  | 0 |  | 0 |
Settlements, assets |  | (4) |  | (5) |  | (7) |  | (13) |
Sales, assets |  | 0 |  | (48) |  | 0 |  | (48) |
Transfers into level 3, assets |  | 0 |  | 0 | [2] | 0 |  | 0 | [2]
Transfers out of level 3, assets |  | 0 |  | 0 | [2] | 0 |  | 0 | [2]
Ending balance, fair value assets |  | 116 |  | 154 |  | 116 |  | 154 |
Change in unrealized gains/(losses) for the period included in earnings for assets still held, assets |  | 20 |  | (1) |  | (14) |  | 38 |
Change in unrealized gains/(losses) for the period included in OCI for Liabilities still held | [1] | 0 |  |  |  | 0 |  |  |
Loan Repurchase Commitments [Member] | Variable Interest Entity Primary Beneficiary [Member] |  |  |  |  |  |  |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |  |  |  |  |  |  |
Beginning balance, fair value assets |  | 506 |  | 420 |  | 486 |  | 418 |
Total gains/(losses) included in earnings, assets |  | 18 |  | 8 |  | 38 |  | 10 |
Unrealized gains/(losses) included in OCI, assets |  | 0 |  | 0 |  | 0 | [1] | 0 |
Purchases, assets |  | 0 |  | 0 |  | 0 |  | 0 |
Issuances, assets |  | 0 |  | 0 |  | 0 |  | 0 |
Settlements, assets |  | 0 |  | 0 |  | 0 |  | 0 |
Sales, assets |  | 0 |  | 0 |  | 0 |  | 0 |
Transfers into level 3, assets |  | 0 |  | 0 | [2] | 0 |  | 0 | [2]
Transfers out of level 3, assets |  | 0 |  | 0 | [2] | 0 |  | 0 | [2]
Ending balance, fair value assets |  | 524 |  | 428 |  | 524 |  | 428 |
Change in unrealized gains/(losses) for the period included in earnings for assets still held, assets |  | 18 |  | 8 |  | 38 |  | 10 |
Change in unrealized gains/(losses) for the period included in OCI for Liabilities still held | [1] | 0 |  |  |  | 0 |  |  |
Corporate Obligations [Member] | Variable Interest Entity Primary Beneficiary [Member] |  |  |  |  |  |  |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |  |  |  |  |  |  |
Beginning balance, fair value assets |  |  |  | 5 |  |  |  | 5 |
Total gains/(losses) included in earnings, assets |  |  |  | 0 |  |  |  | 0 |
Unrealized gains/(losses) included in OCI, assets |  |  |  | 0 |  |  |  | 0 |
Purchases, assets |  |  |  | 0 |  |  |  | 0 |
Issuances, assets |  |  |  | 0 |  |  |  | 0 |
Settlements, assets |  |  |  | (2) |  |  |  | (2) |
Sales, assets |  |  |  | 0 |  |  |  | 0 |
Transfers into level 3, assets | [2] |  |  | 0 |  |  |  | 0 |
Transfers out of level 3, assets | [2] |  |  | (3) |  |  |  | (3) |
Ending balance, fair value assets |  |  |  | 0 |  |  |  | 0 |
Change in unrealized gains/(losses) for the period included in earnings for assets still held, assets |  |  |  | 0 |  |  |  | 0 |
Commercial Mortgage Backed Securities [Member] |  |  |  |  |  |  |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |  |  |  |  |  |  |
Beginning balance, fair value assets |  |  |  | 6 |  |  |  | 7 |
Total gains/(losses) included in earnings, assets |  |  |  | 0 |  |  |  | 0 |
Unrealized gains/(losses) included in OCI, assets |  |  |  | 0 |  |  |  | 0 |
Purchases, assets |  |  |  | 0 |  |  |  | 0 |
Issuances, assets |  |  |  | 0 |  |  |  | 0 |
Settlements, assets |  |  |  | (2) |  |  |  | (3) |
Sales, assets |  |  |  | 0 |  |  |  | 0 |
Transfers into level 3, assets | [2] |  |  | 0 |  |  |  | 0 |
Transfers out of level 3, assets | [2] |  |  | 0 |  |  |  | 0 |
Ending balance, fair value assets |  |  |  | 4 |  |  |  | 4 |
Change in unrealized gains/(losses) for the period included in earnings for assets still held, assets |  |  |  | 0 |  |  |  | 0 |
Collateralized Debt Obligations [Member] | Variable Interest Entity Primary Beneficiary [Member] |  |  |  |  |  |  |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |  |  |  |  |  |  |
Beginning balance, fair value assets |  |  |  | 1 |  |  |  | 1 |
Total gains/(losses) included in earnings, assets |  |  |  | 0 |  |  |  | 0 |
Unrealized gains/(losses) included in OCI, assets |  |  |  | 0 |  |  |  | 0 |
Purchases, assets |  |  |  | 0 |  |  |  | 0 |
Issuances, assets |  |  |  | 0 |  |  |  | 0 |
Settlements, assets |  |  |  | 0 |  |  |  | 0 |
Sales, assets |  |  |  | (1) |  |  |  | (1) |
Transfers into level 3, assets | [2] |  |  | 0 |  |  |  | 0 |
Transfers out of level 3, assets | [2] |  |  | 0 |  |  |  | 0 |
Ending balance, fair value assets |  |  |  | 0 |  |  |  | 0 |
Change in unrealized gains/(losses) for the period included in earnings for assets still held, assets |  |  |  | 0 |  |  |  | 0 |
Other Asset Backed [Member] |  |  |  |  |  |  |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |  |  |  |  |  |  |
Beginning balance, fair value assets |  | 1 |  | 2 |  | 1 |  | 3 |
Total gains/(losses) included in earnings, assets |  | 0 |  | (1) |  | 0 |  | (1) |
Unrealized gains/(losses) included in OCI, assets |  | 0 |  | 0 |  | 0 | [1] | 0 |
Purchases, assets |  | 0 |  | 0 |  | 0 |  | 0 |
Issuances, assets |  | 0 |  | 0 |  | 0 |  | 0 |
Settlements, assets |  | 0 |  | 0 |  | 0 |  | (1) |
Sales, assets |  | 0 |  | 0 |  | 0 |  | 0 |
Transfers into level 3, assets |  | 0 |  | 0 | [2] | 0 |  | 0 | [2]
Transfers out of level 3, assets |  | 0 |  | 0 | [2] | 0 |  | 0 | [2]
Ending balance, fair value assets |  | 1 |  | 1 |  | 1 |  | 1 |
Change in unrealized gains/(losses) for the period included in earnings for assets still held, assets |  | 0 |  | 0 |  | 0 |  | 0 |
Change in unrealized gains/(losses) for the period included in OCI for Liabilities still held | [1] | 0 |  |  |  | 0 |  |  |
Medium Term Notes [Member] |  |  |  |  |  |  |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |  |  |  |  |  |  |
Beginning balance, fair value liabilities |  | 98 |  | 106 |  | 108 |  | 102 |
Total gains/(losses) included in earnings, liabilities |  | (1) |  | (3) |  | 1 |  | 5 |
Unrealized gains/(losses) included in OCI, liabilities |  | (1) |  | 10 |  | (13) | [3] | 6 |
Purchases, liabilities |  | 0 |  | 0 |  | 0 |  | 0 |
Issuances, liabilities |  | 0 |  | 0 |  | 0 |  | 0 |
Settlements, liabilities |  | 0 |  | (3) |  | 0 |  | (3) |
Sales, liabilities |  | 0 |  | 0 |  | 0 |  | 0 |
Transfers into Level 3, liabilities |  | 0 |  | 0 | [2] | 0 |  | 0 | [2]
Transfers out of Level 3, liabilities |  | 0 |  | 0 | [2] | 0 |  | 0 | [2]
Ending balance, fair value liabilities |  | 96 |  | 110 |  | 96 |  | 110 |
Change in unrealized gains/(losses) for the period included in earnings for liabilities still held, liabilities |  | (1) |  | (2) |  | 1 |  | 4 |
Change in Unrealized (Gains)/ Losses for the Period Included in OCI for Liabilities still held |  | (1) | [4] |  |  | (13) | [3] |  |
Credit Derivatives [Member] |  |  |  |  |  |  |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |  |  |  |  |  |  |
Beginning balance, fair value liabilities |  | 8 |  | 19 |  | 7 |  | 33 |
Total gains/(losses) included in earnings, liabilities |  | 0 |  | 1 |  | 1 |  | (13) |
Unrealized gains/(losses) included in OCI, liabilities |  | 0 |  | 0 |  | 0 | [3] | 0 |
Purchases, liabilities |  | 0 |  | 0 |  | 0 |  | 0 |
Issuances, liabilities |  | 0 |  | 0 |  | 0 |  | 0 |
Settlements, liabilities |  | 0 |  | (2) |  | 0 |  | (2) |
Sales, liabilities |  | 0 |  | 0 |  | 0 |  | 0 |
Transfers into Level 3, liabilities |  | 0 |  | 0 | [2] | 0 |  | 0 | [2]
Transfers out of Level 3, liabilities |  | 0 |  | 0 | [2] | 0 |  | 0 | [2]
Ending balance, fair value liabilities |  | 8 |  | 18 |  | 8 |  | 18 |
Change in unrealized gains/(losses) for the period included in earnings for liabilities still held, liabilities |  | 0 |  | 0 |  | 1 |  | (14) |
Change in Unrealized (Gains)/ Losses for the Period Included in OCI for Liabilities still held |  | 0 | [4] |  |  | 0 | [3] |  |
Other Derivatives Liabilities [Member] |  |  |  |  |  |  |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |  |  |  |  |  |  |
Beginning balance, fair value liabilities |  | 37 |  | 7 |  | 34 |  | 7 |
Total gains/(losses) included in earnings, liabilities |  | 0 |  | 9 |  | 3 |  | 9 |
Unrealized gains/(losses) included in OCI, liabilities |  | 0 |  | 0 |  | 0 | [3] | 0 |
Purchases, liabilities |  | 0 |  | 0 |  | 0 |  | 0 |
Issuances, liabilities |  | 0 |  | 0 |  | 0 |  | 0 |
Settlements, liabilities |  | 0 |  | 0 |  | 0 |  | 0 |
Sales, liabilities |  | 0 |  | 0 |  | 0 |  | 0 |
Transfers into Level 3, liabilities |  | 0 |  | 0 | [2] | 0 |  | 0 | [2]
Transfers out of Level 3, liabilities |  | 0 |  | 0 | [2] | 0 |  | 0 | [2]
Ending balance, fair value liabilities |  | 37 |  | 16 |  | 37 |  | 16 |
Change in unrealized gains/(losses) for the period included in earnings for liabilities still held, liabilities |  | 0 |  | 9 |  | 3 |  | 9 |
Change in Unrealized (Gains)/ Losses for the Period Included in OCI for Liabilities still held |  | 0 | [4] |  |  | 0 | [3] |  |
Variable Interest Entity Notes [Member] |  |  |  |  |  |  |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |  |  |  |  |  |  |
Change in Unrealized (Gains)/ Losses for the Period Included in OCI for Liabilities still held |  | (3) | [4] |  |  | (37) | [3] |  |
Variable Interest Entity Notes [Member] | Variable Interest Entity Primary Beneficiary [Member] |  |  |  |  |  |  |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |  |  |  |  |  |  |
Beginning balance, fair value liabilities |  | 281 |  | 397 |  | 347 |  | 366 |
Total gains/(losses) included in earnings, liabilities |  | 16 |  | 9 |  | (9) |  | 50 |
Unrealized gains/(losses) included in OCI, liabilities |  | (3) |  | (1) |  | (38) | [3] | (7) |
Purchases, liabilities |  | 0 |  | 0 |  | 0 |  | 0 |
Issuances, liabilities |  | 0 |  | 0 |  | 0 |  | 4 |
Settlements, liabilities |  | (3) |  | (3) |  | (9) |  | (11) |
Sales, liabilities |  | 0 |  | (60) |  | 0 |  | (60) |
Transfers into Level 3, liabilities |  | 0 |  | 0 | [2] | 0 |  | 0 | [2]
Transfers out of Level 3, liabilities |  | 0 |  | 0 | [2] | 0 |  | 0 | [2]
Ending balance, fair value liabilities |  | 291 |  | 342 |  | 291 |  | 342 |
Change in unrealized gains/(losses) for the period included in earnings for liabilities still held, liabilities |  | 15 |  | 10 |  | (12) |  | 43 |
Currency Derivatives [Member] | Variable Interest Entity Primary Beneficiary [Member] |  |  |  |  |  |  |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |  |  |  |  |  |  |
Beginning balance, fair value assets |  | 18 |  | 14 |  | 8 |  | 17 |
Total gains/(losses) included in earnings, assets |  | (4) |  | (3) |  | 6 |  | (6) |
Unrealized gains/(losses) included in OCI, assets |  | 0 |  | 0 |  | 0 | [1] | 0 |
Purchases, assets |  | 0 |  | 0 |  | 0 |  | 0 |
Issuances, assets |  | 0 |  | 0 |  | 0 |  | 0 |
Settlements, assets |  | 0 |  | 0 |  | 0 |  | 0 |
Sales, assets |  | 0 |  | 0 |  | 0 |  | 0 |
Transfers into level 3, assets |  | 0 |  | 0 | [2] | 0 |  | 0 | [2]
Transfers out of level 3, assets |  | 0 |  | 0 | [2] | 0 |  | 0 | [2]
Ending balance, fair value assets |  | 14 |  | 11 |  | 14 |  | 11 |
Change in unrealized gains/(losses) for the period included in earnings for assets still held, assets |  | (4) |  | (3) |  | 6 |  | (6) |
Change in unrealized gains/(losses) for the period included in OCI for Liabilities still held | [1] | 0 |  |  |  | 0 |  |  |
Other Assets [Member] | Variable Interest Entity Primary Beneficiary [Member] |  |  |  |  |  |  |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |  |  |  |  |  |  |
Beginning balance, fair value assets |  | 15 |  | 15 |  | 18 |  | 14 |
Total gains/(losses) included in earnings, assets |  | (1) |  | 0 |  | (4) |  | 1 |
Unrealized gains/(losses) included in OCI, assets |  | 0 |  | 0 |  | 0 | [1] | 0 |
Purchases, assets |  | 0 |  | 0 |  | 0 |  | 0 |
Issuances, assets |  | 0 |  | 0 |  | 0 |  | 0 |
Settlements, assets |  | 0 |  | 0 |  | 0 |  | 0 |
Sales, assets |  | 0 |  | 0 |  | 0 |  | 0 |
Transfers into level 3, assets |  | 0 |  | 0 | [2] | 0 |  | 0 | [2]
Transfers out of level 3, assets |  | 0 |  | 0 | [2] | 0 |  | 0 | [2]
Ending balance, fair value assets |  | 14 |  | 15 |  | 14 |  | 15 |
Change in unrealized gains/(losses) for the period included in earnings for assets still held, assets |  | (1) |  | 0 |  | (4) |  | 1 |
Change in unrealized gains/(losses) for the period included in OCI for Liabilities still held | [1] | 0 |  |  |  | 0 |  |  |
Other Payable [Member] |  |  |  |  |  |  |  |  |
Accounts Notes And Loans Receivable [Line Items] |  |  |  |  |  |  |  |  |
Beginning balance, fair value liabilities |  |  |  | 3 |  | 4 |  | 5 |
Total gains/(losses) included in earnings, liabilities |  |  |  | 0 |  | 0 |  | 1 |
Unrealized gains/(losses) included in OCI, liabilities |  |  |  | 0 |  | 0 | [3] | 0 |
Purchases, liabilities |  |  |  | 0 |  | 0 |  | 0 |
Issuances, liabilities |  |  |  | 0 |  | 0 |  | 0 |
Settlements, liabilities |  |  |  | 0 |  | (4) |  | (3) |
Sales, liabilities |  |  |  | 0 |  | 0 |  | 0 |
Transfers into Level 3, liabilities |  |  |  | 0 | [2] | 0 |  | 0 | [2]
Transfers out of Level 3, liabilities |  |  |  | 0 | [2] | 0 |  | 0 | [2]
Ending balance, fair value liabilities |  | $ 0 |  | 3 |  | 0 |  | 3 |
Change in unrealized gains/(losses) for the period included in earnings for liabilities still held, liabilities |  |  |  | $ 0 |  | 0 |  | $ 1 |
Change in Unrealized (Gains)/ Losses for the Period Included in OCI for Liabilities still held | [3] |  |  |  |  | $ 0 |  |  |
[1] | Reported within the “Unrealized gains (losses) on available-for-sale securities” on MBIA’s Consolidated Statement of Comprehensive Income/Loss.
[2] | Transferred in and out at the end of the period.
[3] | Reported within the “Instrument-specific credit risk of liabilities measured at fair value” on MBIA’s Consolidated Statement of Comprehensive Income/Loss.
[4] | Reported within the “Instrument-specific credit risk of liabilities measured at fair value” on MBIA’s Consolidated Statement of Comprehensive Income/Loss

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- Definition Amount of unrealized gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3) and still held. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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- Definition Amount of unrealized gain (loss) recognized in other comprehensive income (OCI) from liability measured at fair value on recurring basis using unobservable input (level 3) and still held. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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- Definition Amount of transfers of financial instrument classified as a liability into level 3 of the fair value hierarchy. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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- Definition Amount of transfers of financial instrument classified as a liability out of level 3 of the fair value hierarchy. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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- Definition Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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- Definition Amount of gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1a) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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- Definition Amount of issuances of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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