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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Details) $ in Thousands | 1 Months Ended | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | ---
Feb. 29, 2016 USD ($) investment | Dec. 31, 2015 USD ($) Segment | Mar. 02, 2016 USD ($) | Dec. 31, 2014 USD ($) | Dec. 31, 2013 USD ($)
Property, Plant and Equipment [Line Items] |  |  |  |  |
Period of delinquency after which a loan is placed on non-accrual status |  | 90 days |  |  |
Number of consecutive months for which loans remain current before non-accrual loans are returned to accrual status |  | 6 months |  |  |
Rolling historical period of net losses used in evaluating general component of valuation allowance for loans not impaired but classified as substandard and special mention |  | 5 years |  |  |
Number of most recent years of actual loss history used in determining historical loss experience for all other unclassified loans |  | 2 years |  |  |
Assets under management |  |  |  | $ 1,856,000 | $ 1,956,000
Number of operating segments | Segment |  | 2 |  |  |
Subsequent Events |  |  |  |  |
Deposits |  | $ 1,400,295 |  | 1,280,014 |
Buildings | Minimum |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated useful lives |  | 15 years |  |  |
Buildings | Maximum |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated useful lives |  | 50 years |  |  |
Equipment and Furniture | Minimum |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated useful lives |  | 3 years |  |  |
Equipment and Furniture | Maximum |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated useful lives |  | 10 years |  |  |
Facility Closing | Subsequent Event |  |  |  |  |
Subsequent Events |  |  |  |  |
Deposits |  |  | $ 20,600 |  |
Expected cost |  |  | $ 450 |  |
US Treasury Notes Securities | Subsequent Event |  |  |  |  |
Subsequent Events |  |  |  |  |
Number of investments sold | investment | 2 |  |  |  |
Notional value of investment | $ 14,500 |  |  |  |
Gain on sale of investments | $ 908 |  |  |  |
Chemung Financial Corporation |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |
Assets under management |  |  |  | $ 304,100 | $ 287,100

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