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Commitments And Contingencies (Details) (USD $) In Millions, unless otherwise specified	Jul. 31, 2011	Mar. 15, 2011	Jan. 26, 2011
Commitments And Contingencies
Number of causes of actions purported			7
Plaintiffs, number of domestic and international financial institutions		19
Securities litigation settlement	$ 68

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Number of causes of actions purported.

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Plaintiffs, number of domestic and international financial institutions.

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Securities Litigation Settlement

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