XML 62 R33.htm IDEA: XBRL DOCUMENT ﻿
v2.3.0.11

Earnings Per Share (Tables) | 6 Months Ended
--- | ---
Jun. 30, 2011
Earnings Per Share |
Schedule Of Basic And Diluted Earnings Per Share |
|  | Three Months Ended June 30, |  |  | Six Months Ended June 30, |
$ in millions except share and per share amounts |  | 2011 |  |  | 2010 |  |  | 2011 |  |  | 2010 |
Net income (loss) |  | $ | 137 |  |  | $ | 1,295 |  |  | $ | (1,138) |  |  | $ | (185) |
Basic weighted average shares(1) |  |  | 199,295,797 |  |  |  | 204,377,833 |  |  |  | 199,602,865 |  |  |  | 204,639,226 |
Effect of common stock equivalents: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock options |  |  | 768,882 |  |  |  | 543,840 |  |  |  | - |  |  |  | - |
Diluted weighted average shares |  |  | 200,064,679 |  |  |  | 204,921,673 |  |  |  | 199,602,865 |  |  |  | 204,639,226 |
Net income (loss) per common share: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basic |  | $ | 0.69 |  |  | $ | 6.34 |  |  | $ | (5.70) |  |  | $ | (0.90) |
Diluted |  | $ | 0.68 |  |  | $ | 6.32 |  |  | $ | (5.70) |  |  | $ | (0.90) |
(1) - Includes 5,035,256 and 5,463,932 of unvested restricted stock and units that receive nonforfeitable dividends or dividend equivalents for the three months ended June 30, 2011 and 2010, respectively. Includes 5,102,013 and 5,424,146 of unvested restricted stock and units that receive nonforfeitable dividends or dividend equivalents for the six months ended June 30, 2011 and 2010, respectively.

X
- Definition Earnings Per Share Disclosure [Abstract] + Details
Name: | mbi_EarningsPerShareDisclosureAbstract
Namespace Prefix: | mbi
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Schedule of Basic and Diluted Earnings Per Share [Text Block] + Details
Name: | mbi_ScheduleOfBasicAndDilutedEarningsPerShareTextBlock
Namespace Prefix: | mbi
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration