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LOANS AND ALLOWANCE FOR LOAN LOSSES - Troubled Debt Restructuring (Details) | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2017 USD ($) loan | Sep. 30, 2016 | Sep. 30, 2016 loan | Sep. 30, 2016 USD ($) | Sep. 30, 2017 USD ($) loan | Sep. 30, 2016 USD ($) loan | Dec. 31, 2016 USD ($)
Troubled Debt Restructurings [Abstract] |  |  |  |  |  |  |
Recorded investment in troubled debt restructurings | $ 9,200,000 |  |  |  | $ 9,200,000 |  | $ 10,200,000
Troubled debt restructuring reserve | 1,000,000 |  |  |  | 1,000,000 |  | 900,000
Troubled debt restructurings accruing interest under modified terms | 2,000,000 |  |  |  | 2,000,000 |  | 5,800,000
Troubled debt restructurings on non-accrual status | 7,200,000 |  |  |  | 7,200,000 |  | 4,400,000
Additional amounts committed to customers with loans classified as troubled debt restructurings | $ 0 |  |  |  | $ 0 |  | $ 0
Number of Loans | 0 | 0 | 0 |  | 0 |  |
Troubled debt restructuring, extension of maturity date |  |  |  |  |  | 13 years |
Increase (decrease) in allowance for loan losses | $ 100,000 |  |  | $ 0 | $ 200,000 | $ 0 |
TDR charge-offs | $ 0 |  |  | $ 0 | $ 0 | $ 0 |
Loans by class modified as troubled debt restructurings [Abstract] |  |  |  |  |  |  |
Number of loans | loan | 2 |  | 0 |  | 5 | 8 |
Pre-modification outstanding recorded investment | $ 506,000 |  |  |  | $ 948,000 | $ 681,000 |
Post-modification outstanding recorded investment | $ 506,000 |  |  |  | $ 948,000 | $ 691,000 |
Commercial mortgages |  |  |  |  |  |  |
Troubled Debt Restructurings [Abstract] |  |  |  |  |  |  |
Number of Loans | loan |  |  |  |  |  | 5 |
Troubled debt restructurings, modifications, consolidated loans |  |  |  |  |  | 1 |
Residential mortgages |  |  |  |  |  |  |
Troubled Debt Restructurings [Abstract] |  |  |  |  |  |  |
Number of Loans | loan |  |  |  |  |  | 1 |
Troubled debt restructuring, extension of maturity date |  |  |  |  | 5 years |  |
Troubled debt restructuring, interest capitalized |  |  |  |  |  | $ 4,000 |
Commercial Mortgages | Commercial mortgages |  |  |  |  |  |  |
Troubled Debt Restructurings [Abstract] |  |  |  |  |  |  |
Number of Loans | loan |  |  |  |  |  | 2 |
Loans by class modified as troubled debt restructurings [Abstract] |  |  |  |  |  |  |
Number of loans | loan |  |  |  |  | 1 | 5 |
Pre-modification outstanding recorded investment |  |  |  |  | $ 166,000 | $ 312,000 |
Post-modification outstanding recorded investment |  |  |  |  | $ 166,000 | 310,000 |
Recorded Investment |  |  |  |  |  | $ 2,100,000 |
Residential mortgages |  |  |  |  |  |  |
Loans by class modified as troubled debt restructurings [Abstract] |  |  |  |  |  |  |
Number of loans | loan |  |  |  |  | 1 | 2 |
Pre-modification outstanding recorded investment |  |  |  |  | $ 105,000 | $ 295,000 |
Post-modification outstanding recorded investment |  |  |  |  | $ 105,000 | $ 307,000 |
Consumer loans: | Home equity lines and loans |  |  |  |  |  |  |
Loans by class modified as troubled debt restructurings [Abstract] |  |  |  |  |  |  |
Number of loans | loan |  |  |  |  |  | 1 |
Pre-modification outstanding recorded investment |  |  |  |  |  | $ 74,000 |
Post-modification outstanding recorded investment |  |  |  |  |  | $ 74,000 |
Commercial and industrial |  |  |  |  |  |  |
Troubled Debt Restructurings [Abstract] |  |  |  |  |  |  |
Number of Loans | loan | 2 |  |  |  | 2 |  |
Financing receivable, modifications, release of collateral, number of contracts | 1 |  |  |  |  |  |
Troubled debt restructurings, modifications, consolidated loans |  |  |  |  | 1 |  |
Troubled debt restructuring, extension of maturity date |  |  |  |  | 2 years |  |
Commercial and industrial | Commercial mortgages |  |  |  |  |  |  |
Troubled Debt Restructurings [Abstract] |  |  |  |  |  |  |
Number of Loans | loan |  |  |  |  | 1 |  |
Commercial and industrial | Commercial and agricultural: |  |  |  |  |  |  |
Loans by class modified as troubled debt restructurings [Abstract] |  |  |  |  |  |  |
Number of loans | loan | 2 |  |  |  | 3 |  |
Pre-modification outstanding recorded investment | $ 506,000 |  |  |  | $ 677,000 |  |
Post-modification outstanding recorded investment | $ 506,000 |  |  |  | $ 677,000 |  |

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