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    <Log type="Info">'Monetary' elements on report '162 - Disclosure - Loans and Leases - Additional Information (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '169 - Disclosure - Pledged Assets - Additional Information (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '186 - Disclosure - Contingent Liabilities - Additional Information (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">Process Flow-Through: 103 - Statement - Consolidated Balance Sheet</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Mar. 31, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2011'</Log>
    <Log type="Info">Process Flow-Through: 104 - Statement - Consolidated Balance Sheet (Parenthetical)</Log>
    <Log type="Info">Process Flow-Through: 105 - Statement - Consolidated Statement Of Income</Log>
    <Log type="Info">Process Flow-Through: 106 - Statement - Consolidated Statement Of Comprehensive Income</Log>
    <Log type="Info">Process Flow-Through: 107 - Statement - Consolidated Statement Of Income (Parenthetical)</Log>
    <Log type="Info">Process Flow-Through: 109 - Statement - Consolidated Statement Of Cash Flows</Log>
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    <File>ntrs-20130331_def.xml</File>
    <File>ntrs-20130331_lab.xml</File>
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  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
