XML 81 R72.htm IDEA: XBRL DOCUMENT ﻿
v2.3.0.11

Investment Income And Gains And Losses (Significant Inputs Used In Schedule Of Measurement Of Credit Loss Component Recognized In Earnings For Each Significant Class Of ABS) (Details) | 6 Months Ended
--- | ---
Jun. 30, 2011 | Jun. 30, 2010
Expected size of losses, Weighted average | 67.10% | [1],[2] | 64.68% | [1],[2]
Current subordination levels, Weighted average | 0.29% | [1],[3] | 5.91% | [1],[3]
Prepayment speed (annual CPR), Weighted average | 19.40 | [1],[4] | 9.83 | [1],[4]
Minimum Range [Member] |  |  |  |
Expected size of losses, Range | 0.00% | [2],[5] | 0.31% | [2],[5]
Current subordination levels, Range | 0.00% | [3],[5] | 0.00% | [3],[5]
Prepayment speed (annual CPR), Range | 0.00 | [4],[5] | 0.00 | [4],[5]
Maximum Range [Member] |  |  |  |
Expected size of losses, Range | 100.00% | [2],[5] | 100.00% | [2],[5]
Current subordination levels, Range | 14.19% | [3],[5] | 42.16% | [3],[5]
Prepayment speed (annual CPR), Range | 100.00 | [4],[5] | 51.77 | [4],[5]
[1] | Calculated by weighting the relevant input/assumption for each individual security by the outstanding notional of the security.
[2] | Represents future expected credit losses on impaired assets expressed as a percentage of total outstanding balance.
[3] | Represents current level of credit protection (subordination) for the securities, expressed as a percentage of the balance of the collateral group backing the bond.
[4] | Values represent high and low points of lifetime vectors of constant prepayment rates.
[5] | Represents the range of inputs/assumptions based upon the individual securities within each category.

X
- Definition Represents the range of inputs/assumptions used to calculate current level of credit protection (subordination) for the securities, expressed as a percentage of total current underlying loan balance + Details
Name: | mbi_AssumptionForMeasurementOfCurrentSubordinationLevelsRange
Namespace Prefix: | mbi
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the range of inputs/assumptions used to calculate future expected credit losses on impaired assets expressed as a percentage of total current outstanding balance + Details
Name: | mbi_AssumptionForMeasurementOfExpectedSizeOfLossesRange
Namespace Prefix: | mbi
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the range of inputs/assumptions used to calculate the high and low points of lifetime vectors of constant prepayment rates + Details
Name: | mbi_AssumptionForMeasurementOfPrepaymentSpeedRange
Namespace Prefix: | mbi
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted average current subordination levels represents current level of credit protection (subordination) for the securities, expressed as a percentage of total current underlying loan balance calculated by weighting the relevant assumption for each individual security by current outstanding notional of the security. + Details
Name: | mbi_WeightedAverageAssumptionForMeasurementOfCurrentSubordinationLevels
Namespace Prefix: | mbi
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted average expected size of losses represents future expected credit losses on impaired assets expressed as a percentage of total current outstanding balance calculated by weighting the relevant assumption for each individual security by current outstanding notional of the security. + Details
Name: | mbi_WeightedAverageAssumptionForMeasurementOfExpectedSizeOfLosses
Namespace Prefix: | mbi
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted average prepayment speed represents high and low points of lifetime vectors of constant prepayment rates calculated by weighting the relevant assumption for each individual security by current outstanding notional of the security. + Details
Name: | mbi_WeightedAverageAssumptionForMeasurementOfPrepaymentSpeedAnnualCpr
Namespace Prefix: | mbi
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | duration