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BASIS OF PRESENTATION (Policies) | 3 Months Ended
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Mar. 31, 2018
BASIS OF PRESENTATION [Abstract] |
Basis of Presentation | The interim financial data as of and for the three months ended March 31, 2018 is unaudited; however, in the opinion of Community Bank System, Inc. (the “Company”), the interim data includes all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement of the results for the interim periods in conformity with generally accepted accounting principles (“GAAP”). The results of operations for the interim periods are not necessarily indicative of the results that may be expected for the full year or any other interim period.

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