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Commitments And Contingencies (Details) (USD $) In Millions, unless otherwise specified | Aug. 08, 2011 | Jul. 31, 2011 | Jun. 13, 2011
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Commitments And Contingencies [Abstract] |  |  |
Number of causes of actions purported |  |  | 7
Plaintiffs, number of domestic and international financial institutions | 10 |  |
Securities litigation settlement |  | $ 68 |

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