XML 67 R51.htm IDEA: XBRL DOCUMENT v3.21.1
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Property, Plant and Equipment [Line Items]        
Adjustments due to new accounting pronouncements $ 199,699 $ 182,627 $ 165,029 $ 149,813
Period of delinquency after which a loan is placed on non-accrual status (days) 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 (years) 5 years      
Number of most recent years of actual loss history used in determining historical loss experience for all other unclassified loans (years) 2 years      
Assets under management $ 2,091,000 1,915,000    
Buildings | Minimum        
Property, Plant and Equipment [Line Items]        
Estimated useful lives (years) 15 years      
Buildings | Maximum        
Property, Plant and Equipment [Line Items]        
Estimated useful lives (years) 50 years      
Equipment and Furniture | Minimum        
Property, Plant and Equipment [Line Items]        
Estimated useful lives (years) 3 years      
Equipment and Furniture | Maximum        
Property, Plant and Equipment [Line Items]        
Estimated useful lives (years) 10 years      
Chemung Financial Corporation        
Property, Plant and Equipment [Line Items]        
Assets under management $ 305,500 289,700    
Retained Earnings        
Property, Plant and Equipment [Line Items]        
Adjustments due to new accounting pronouncements 168,006 153,701 143,129 128,453
Accumulated Other Comprehensive Income (Loss)        
Property, Plant and Equipment [Line Items]        
Adjustments due to new accounting pronouncements $ 2,401 $ (5,799) $ (11,411) (10,340)
Accumulated Other Comprehensive Income (Loss) | Cumulative Effect, Period of Adoption, Adjustment        
Property, Plant and Equipment [Line Items]        
Adjustments due to new accounting pronouncements       (202)
Accounting Standards Update 2016-01 | Cumulative Effect, Period of Adoption, Adjustment        
Property, Plant and Equipment [Line Items]        
Adjustments due to new accounting pronouncements [1]       (162)
Accounting Standards Update 2016-01 | Retained Earnings | Cumulative Effect, Period of Adoption, Adjustment        
Property, Plant and Equipment [Line Items]        
Adjustments due to new accounting pronouncements [1]       40
Accounting Standards Update 2016-01 | Accumulated Other Comprehensive Income (Loss) | Cumulative Effect, Period of Adoption, Adjustment        
Property, Plant and Equipment [Line Items]        
Adjustments due to new accounting pronouncements [1]       $ (202)
[1] Due to implementation of ASC 2016-01. See "Adoption of New Accounting Standards" discussion in Note 1.