XML 119 R84.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Investments (Credit Ratings Of Asset-Backed And Mortgage-Backed Securities And Corporate Obligations In Available-For-Sale Investments For Which Fair Value Was Less Than Amortized Cost) (Detail) (USD $) In Millions, unless otherwise specified | Dec. 31, 2013 | Dec. 31, 2012
--- | --- | ---
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | $ 3,457 | $ 1,284
Gross unrealized losses | (229) | (152)
Asset-backed [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 208 |
Gross unrealized losses | (72) |
Mortgage-backed [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 907 |
Gross unrealized losses | (37) |
Corporate Obligations [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 870 |
Gross unrealized losses | (38) |
Total ABS MBS and Corporate Obligations [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 1,985 |
Gross unrealized losses | (147) |
Moody's Aaa [Member] | Asset-backed [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 16 |
Gross unrealized losses | 0 |
Moody's Aaa [Member] | Mortgage-backed [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 868 |
Gross unrealized losses | (31) |
Moody's Aaa [Member] | Corporate Obligations [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 151 |
Gross unrealized losses | (1) |
Moody's Aaa [Member] | Total ABS MBS and Corporate Obligations [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 1,035 |
Gross unrealized losses | (32) |
Moodys Aa 1 Rating [Member] | Asset-backed [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 62 |
Gross unrealized losses | (4) |
Moodys Aa 1 Rating [Member] | Mortgage-backed [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 7 |
Gross unrealized losses | 0 |
Moodys Aa 1 Rating [Member] | Corporate Obligations [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 238 |
Gross unrealized losses | (9) |
Moodys Aa 1 Rating [Member] | Total ABS MBS and Corporate Obligations [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 307 |
Gross unrealized losses | (13) |
Moody's A1 [Member] | Asset-backed [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 1 |
Gross unrealized losses | 0 |
Moody's A1 [Member] | Mortgage-backed [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 4 |
Gross unrealized losses | 0 |
Moody's A1 [Member] | Corporate Obligations [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 275 |
Gross unrealized losses | (12) |
Moody's A1 [Member] | Total ABS MBS and Corporate Obligations [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 280 |
Gross unrealized losses | (12) |
Moody's Baa 1 Rating [Member] | Asset-backed [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 2 |
Gross unrealized losses | 0 |
Moody's Baa 1 Rating [Member] | Mortgage-backed [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 6 |
Gross unrealized losses | (1) |
Moody's Baa 1 Rating [Member] | Corporate Obligations [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 76 |
Gross unrealized losses | (5) |
Moody's Baa 1 Rating [Member] | Total ABS MBS and Corporate Obligations [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 84 |
Gross unrealized losses | (6) |
Below Investment Grade [Member] | Asset-backed [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 126 |
Gross unrealized losses | (68) |
Below Investment Grade [Member] | Mortgage-backed [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 7 |
Gross unrealized losses | (1) |
Below Investment Grade [Member] | Corporate Obligations [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 17 |
Gross unrealized losses | (1) |
Below Investment Grade [Member] | Total ABS MBS and Corporate Obligations [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 150 |
Gross unrealized losses | (70) |
Not Rated [Member] | Asset-backed [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 1 |
Gross unrealized losses | 0 |
Not Rated [Member] | Mortgage-backed [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 15 |
Gross unrealized losses | (4) |
Not Rated [Member] | Corporate Obligations [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 113 |
Gross unrealized losses | (10) |
Not Rated [Member] | Total ABS MBS and Corporate Obligations [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Fair value | 129 |
Gross unrealized losses | $ (14) |

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_AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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