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Loss And Loss Adjustment Expense Reserves (RMBS Reserves) (Narrative) (Detail) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2016 | Jun. 30, 2015 | Jun. 30, 2016 | Jun. 30, 2015 | Dec. 31, 2015
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |  |  |
Insurance loss recoverable |  | $ 365 |  | $ 365 |  | $ 577
Schedule Of Insured Financial Obligations With Credit Deterioration Insured Contractual Payments Outstanding Principal | [1] | 10,642 |  | 10,642 |  | 11,160
Policyholder (Benefits) And Claims Incurred Net |  | 77 | $ 46 | 99 | $ 40 |
Total excess spread recoveries |  | 363 |  | 363 |  | 571
Contract claims on ineligible mortgage loans inception to date, incurred loss on transactions |  | 430 |  | 430 |  |
Loss And Lae Reserves [Member] |  |  |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |  |  |
Loss and loss adjustment expense reserves |  | 546 |  | 546 |  | 516
Expected recoveries of future payments |  | 91 |  | 91 |  | 100
First Lien R M B S Reserves [Member] | Loss And Lae Reserves [Member] |  |  |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |  |  |
Loss and loss adjustment expense reserves |  | 327 |  | 327 |  | 277
First Lien R M B S Reserves [Member] | Variable Interest Entity Primary Beneficiary [Member] | Loss And Lae Reserves [Member] |  |  |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |  |  |
Loss and loss adjustment expense reserves |  | 18 |  | 18 |  | 5
Second Lien Rmbs And Heloc And Ces [Member] |  |  |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |  |  |
Addition to case basis reserves if losses remain at peak levels |  |  |  | 26 |  |
Second Lien Rmbs And Heloc And Ces [Member] | Excess Spread [Member] |  |  |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |  |  |
Insurance loss recoverable |  | 319 |  | 319 |  | 382
Total excess spread recoveries |  | 408 |  | 408 |  | 499
Expected recoveries of future payments |  | 13 |  | 13 |  | 24
Second Lien Rmbs And Heloc And Ces [Member] | Excess Spread [Member] | Variable Interest Entity Primary Beneficiary [Member] |  |  |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |  |  |
Insurance loss recoverable |  | 75 |  | 75 |  | 87
Total excess spread recoveries |  | 76 |  | 76 |  | 93
Expected recoveries of future payments |  | 1 |  | 1 |  | 6
U S Public Finance Insurance [Member] |  |  |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |  |  |
Loss and loss adjustment expense reserves |  | 58 |  | 58 |  | 45
Insurance loss recoverable |  | 2 |  | 2 |  | 4
Policyholder (Benefits) And Claims Incurred Net |  | 9 | $ 8 | 18 | $ 2 |
U S Public Finance Insurance [Member] | General obligations |  |  |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |  |  |
Schedule Of Insured Financial Obligations With Credit Deterioration Insured Contractual Payments Outstanding Principal |  | 59,900 |  | 59,900 |  | 70,000
U S Public Finance Insurance [Member] | General obligations | Classified [Member] |  |  |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |  |  |
Schedule Of Insured Financial Obligations With Credit Deterioration Insured Contractual Payments Outstanding Principal |  | 1,100 |  | 1,100 |  | 79
Second Lien R M B S Securitizations [Member] | Loss And Lae Reserves [Member] |  |  |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |  |  |
Loss and loss adjustment expense reserves |  | 47 |  | 47 |  | 51
Second Lien R M B S Securitizations [Member] | Variable Interest Entity Primary Beneficiary [Member] |  |  |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |  |  |
Loss and loss adjustment expense reserves |  | $ 16 |  | $ 16 |  | $ 16
[1] | Represents contractual principal and interest payments due by the issuer of the obligations insured by MBIA.

X
- Definition Contract Claims On Ineligible Mortgage Loans Inception To Date Incurred Loss On Transactions + References No definition available. + Details
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- Definition Gross reserve, recoveries on unpaid losses + 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
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- Definition Carrying amount as of the balance sheet date of amounts expected to be recovered under the terms of insurance contracts. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.17) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition The amount needed to reflect the estimated ultimate cost of settling claims relating to insured events that have occurred on or before the balance sheet date, whether or not reported to the insurer at that date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (a),(b),(c) -URI http://asc.fasb.org/extlink&oid=6482485&loc=d3e14764-158437 + Details
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- Definition Amount, after effects of policies assumed or ceded, of expense related to the provision for policy benefits and costs incurred. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.5) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6480758&loc=d3e6811-158387 + Details
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- Definition This element represents the amount of insured contractual payments outstanding attributable to the principal of the underlying insured obligations for financial guarantee insurance contracts presented in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 9 -Subparagraph (a)(5)(iii) -URI http://asc.fasb.org/extlink&oid=6933314&loc=SL5749324-161292 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 55 -Paragraph 32 -URI http://asc.fasb.org/extlink&oid=34726416&loc=SL5751133-161288 + Details
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- Details
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