XML 103 R61.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Investments (Gross Unrealized Losses Related To Available-For-Sale And Held-To-Maturity Investments) (Detail) (USD $) In Millions, unless otherwise specified | Sep. 30, 2013 | Dec. 31, 2012
--- | --- | ---
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value | $ 2,150 | $ 702
Less than 12 months, unrealized losses | (99) | (4)
12 months or longer, fair value | 320 | 582
12 months or longer, unrealized losses | (86) | (148)
Total available-for-sale, fair value | 2,470 | 1,284
Total available-for-sale, unrealized losses | (185) | (152)
Held To Maturity Securities [Abstract] |  |
Less than 12 months, fair value | 0 | 297
Less than 12 months, unrealized losses | 0 | (19)
12 months or longer, fair value | 1,174 | 1,287
12 months or longer, unrealized losses | (251) | (138)
Total held-to-maturity, fair value | 1,174 | 1,584
Total held-to-maturity, unrealized losses | (251) | (157)
Corporate Obligations [Member] | Variable Interest Entity Primary Beneficiary [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value |  | 0
Less than 12 months, unrealized losses |  | 0
12 months or longer, fair value |  | 31
12 months or longer, unrealized losses |  | (6)
Total available-for-sale, fair value |  | 31
Total available-for-sale, unrealized losses |  | (6)
Held To Maturity Securities [Abstract] |  |
Less than 12 months, fair value | 0 | 297
Less than 12 months, unrealized losses | 0 | (19)
12 months or longer, fair value | 1,174 | 1,287
12 months or longer, unrealized losses | (251) | (138)
Total held-to-maturity, fair value | 1,174 | 1,584
Total held-to-maturity, unrealized losses | (251) | (157)
Residential Mortgage Backed Non Agency [Member] | Variable Interest Entity Primary Beneficiary [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value |  | 0
Less than 12 months, unrealized losses |  | 0
12 months or longer, fair value |  | 82
12 months or longer, unrealized losses |  | (10)
Total available-for-sale, fair value |  | 82
Total available-for-sale, unrealized losses |  | (10)
Collateralized Debt Obligations [Member] | Variable Interest Entity Primary Beneficiary [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value |  | 0
Less than 12 months, unrealized losses |  | 0
12 months or longer, fair value |  | 85
12 months or longer, unrealized losses |  | (8)
Total available-for-sale, fair value |  | 85
Total available-for-sale, unrealized losses |  | (8)
Other Asset Backed [Member] | Variable Interest Entity Primary Beneficiary [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value |  | 0
Less than 12 months, unrealized losses |  | 0
12 months or longer, fair value |  | 0
12 months or longer, unrealized losses |  | 0
Total available-for-sale, fair value |  | 0
Total available-for-sale, unrealized losses |  | 0
Perpetual Debt And Equity Securities [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value | 4 | 1
Less than 12 months, unrealized losses | 0 | 0
12 months or longer, fair value | 0 | 1
12 months or longer, unrealized losses | 0 | 0
Total available-for-sale, fair value | 4 | 2
Total available-for-sale, unrealized losses | 0 | 0
Fixed Maturities [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value | 2,146 | 701
Less than 12 months, unrealized losses | (99) | (4)
12 months or longer, fair value | 320 | 383
12 months or longer, unrealized losses | (86) | (124)
Total available-for-sale, fair value | 2,466 | 1,084
Total available-for-sale, unrealized losses | (185) | (128)
Fixed Maturities [Member] | U S Treasury And Government [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value | 208 | 234
Less than 12 months, unrealized losses | (8) | (1)
12 months or longer, fair value | 2 | 0
12 months or longer, unrealized losses | 0 | 0
Total available-for-sale, fair value | 210 | 234
Total available-for-sale, unrealized losses | (8) | (1)
Fixed Maturities [Member] | US States And Political Subdivisions [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value | 730 | 69
Less than 12 months, unrealized losses | (48) | 0
12 months or longer, fair value | 58 | 87
12 months or longer, unrealized losses | (4) | (12)
Total available-for-sale, fair value | 788 | 156
Total available-for-sale, unrealized losses | (52) | (12)
Fixed Maturities [Member] | Foreign Government Debt [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value | 12 | 11
Less than 12 months, unrealized losses | 0 | 0
12 months or longer, fair value | 0 | 1
12 months or longer, unrealized losses | 0 | 0
Total available-for-sale, fair value | 12 | 12
Total available-for-sale, unrealized losses | 0 | 0
Fixed Maturities [Member] | Corporate Obligations [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value | 610 | 202
Less than 12 months, unrealized losses | (23) | (2)
12 months or longer, fair value | 20 | 57
12 months or longer, unrealized losses | (3) | (18)
Total available-for-sale, fair value | 630 | 259
Total available-for-sale, unrealized losses | (26) | (20)
Fixed Maturities [Member] | Residential Mortgage Backed Agency [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value | 528 | 173
Less than 12 months, unrealized losses | (18) | (1)
12 months or longer, fair value | 32 | 38
12 months or longer, unrealized losses | 0 | 0
Total available-for-sale, fair value | 560 | 211
Total available-for-sale, unrealized losses | (18) | (1)
Fixed Maturities [Member] | Residential Mortgage Backed Non Agency [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value | 5 | 4
Less than 12 months, unrealized losses | 0 | 0
12 months or longer, fair value | 23 | 28
12 months or longer, unrealized losses | (6) | (8)
Total available-for-sale, fair value | 28 | 32
Total available-for-sale, unrealized losses | (6) | (8)
Fixed Maturities [Member] | Commercial Mortgage Backed Securities [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value | 22 | 3
Less than 12 months, unrealized losses | (1) | 0
12 months or longer, fair value | 1 | 27
12 months or longer, unrealized losses | 0 | (4)
Total available-for-sale, fair value | 23 | 30
Total available-for-sale, unrealized losses | (1) | (4)
Fixed Maturities [Member] | Collateralized Debt Obligations [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value | 9 | 1
Less than 12 months, unrealized losses | (1) | 0
12 months or longer, fair value | 128 | 80
12 months or longer, unrealized losses | (56) | (71)
Total available-for-sale, fair value | 137 | 81
Total available-for-sale, unrealized losses | (57) | (71)
Fixed Maturities [Member] | Other Asset Backed [Member] |  |
Available For Sale Securities [Abstract] |  |
Less than 12 months, fair value | 22 | 4
Less than 12 months, unrealized losses | 0 | 0
12 months or longer, fair value | 56 | 65
12 months or longer, unrealized losses | (17) | (11)
Total available-for-sale, fair value | 78 | 69
Total available-for-sale, unrealized losses | $ (17) | $ (11)

X
- Definition Amount of accumulated pre-tax unrealized loss on investments classified as available-for-sale that have been in a loss position fortwelve months or longer impacting investments. + References No definition available. + Details
Name: | mbi_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLossesAccumulatedInInvestments
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of accumulated pre-tax unrealized losses before deducting pre-tax unrealized gains on investments in available-for-sale securities impacting investments. + References No definition available. + Details
Name: | mbi_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAggregateLossesAccumulatedInInvestments
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of accumulated pre-tax unrealized loss on investments classified as available-for-sale that have been in a loss position for less than twelve months impacting investments. + References No definition available. + Details
Name: | mbi_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLossesAccumulatedInInvestments
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition This item represents the excess of amortized cost basis over fair value of securities that have been in a loss position twelve months or longer for those securities which are categorized as held-to-maturity. + References No definition available. + Details
Name: | mbi_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition This item represents the excess of amortized cost over fair value of securities in a loss position and which are categorized as held-to-maturity. + References No definition available. + Details
Name: | mbi_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionAccumulatedLoss
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition This item represents the excess of amortized cost basis over fair value of securities that have been in a loss position for less than twelve months for those securities which are categorized as held-to-maturity. + References No definition available. + Details
Name: | mbi_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_AvailableForSaleSecuritiesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for twelve months or longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents the fair value of securities categorized as held-to-maturity which are in an unrealized loss position. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
Name: | us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents the fair value of securities categorized as held-to-maturity that have been in a continuous unrealized loss position for less than twelve months. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
Name: | us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents the fair value of securities categorized as held-to-maturity securities that have been in a continuous unrealized loss position for twelve months or longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
Name: | us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_HeldToMaturitySecuritiesUnclassifiedAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration