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USD ($)
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USD ($)
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USD ($)
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USD ($)
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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USD ($)
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As of December 31, 2010, there was an additional allowance for loan losses of $31 million associated with loans and leases that were not impaired. 136Loans and Leases (Impaired Loans) (Details) (USD $)MillionsUnKnownUnKnownUnKnownfalsetrue