FAIR VALUE - Quantitative Information (Details) - Significant Unobservable Inputs (Level 3) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Impaired Loans: | Non-recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	$ 2,913	$ 1,456
Other real estate owned: | Non-recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	144	574
Derivative Liabilities | Recurring | Historical trend
Information related to Level 3 non-recurring fair value measurement [Abstract]
Liabilities, fair value disclosure	$ 230	$ 140
Derivative Liabilities | Recurring | Historical trend | Minimum
Information related to Level 3 non-recurring fair value measurement [Abstract]
Credit default rate	7.27%	7.46%
Derivative Liabilities | Recurring | Historical trend | Maximum
Information related to Level 3 non-recurring fair value measurement [Abstract]
Credit default rate	7.27%	7.46%
Derivative Liabilities | Recurring | Historical trend | Weighted Average
Information related to Level 3 non-recurring fair value measurement [Abstract]
Credit default rate	7.27%	7.46%
Commercial and Industrial | Impaired Loans: | Non-recurring | Sales comparison
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure		$ 1,456
Commercial and Industrial | Impaired Loans: | Non-recurring | Sales comparison | Minimum
Information related to Level 3 non-recurring fair value measurement [Abstract]
Discount to appraised value		11.76%
Commercial and Industrial | Impaired Loans: | Non-recurring | Sales comparison | Maximum
Information related to Level 3 non-recurring fair value measurement [Abstract]
Discount to appraised value		11.76%
Commercial and Industrial | Impaired Loans: | Non-recurring | Sales comparison | Weighted Average
Information related to Level 3 non-recurring fair value measurement [Abstract]
Discount to appraised value		11.76%
Commercial and Industrial | Other real estate owned: | Non-recurring | Sales comparison | Minimum
Information related to Level 3 non-recurring fair value measurement [Abstract]
Discount to appraised value	22.00%	10.00%
Commercial and Industrial | Other real estate owned: | Non-recurring | Sales comparison | Maximum
Information related to Level 3 non-recurring fair value measurement [Abstract]
Discount to appraised value	22.00%	24.80%
Commercial and Industrial | Other real estate owned: | Non-recurring | Sales comparison | Weighted Average
Information related to Level 3 non-recurring fair value measurement [Abstract]
Discount to appraised value	22.00%	17.72%
Commercial mortgages, other | Impaired Loans: | Non-recurring | Sales comparison
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	$ 2,913
Commercial mortgages, other | Impaired Loans: | Non-recurring | Sales comparison | Minimum
Information related to Level 3 non-recurring fair value measurement [Abstract]
Discount to appraised value		10.00%
Commercial mortgages, other | Impaired Loans: | Non-recurring | Sales comparison | Maximum
Information related to Level 3 non-recurring fair value measurement [Abstract]
Discount to appraised value		11.76%
Commercial mortgages, other | Impaired Loans: | Non-recurring | Sales comparison | Weighted Average
Information related to Level 3 non-recurring fair value measurement [Abstract]
Discount to appraised value		10.89%
Commercial mortgages, other | Other real estate owned: | Non-recurring | Sales comparison
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	$ 62	$ 213
Residential mortgages | Other real estate owned: | Non-recurring | Minimum
Information related to Level 3 non-recurring fair value measurement [Abstract]
Discount to appraised value	13.14%	20.80%
Residential mortgages | Other real estate owned: | Non-recurring | Maximum
Information related to Level 3 non-recurring fair value measurement [Abstract]
Discount to appraised value	13.14%	39.78%
Residential mortgages | Other real estate owned: | Non-recurring | Weighted Average
Information related to Level 3 non-recurring fair value measurement [Abstract]
Discount to appraised value	13.14%	22.94%
Residential mortgages | Other real estate owned: | Non-recurring | Sales comparison
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	$ 27	$ 204
Home equity lines and loans | Other real estate owned: | Non-recurring | Sales comparison
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	$ 55	$ 157
Home equity lines and loans | Other real estate owned: | Non-recurring | Sales comparison | Minimum
Information related to Level 3 non-recurring fair value measurement [Abstract]
Discount to appraised value	20.80%	20.80%
Home equity lines and loans | Other real estate owned: | Non-recurring | Sales comparison | Maximum
Information related to Level 3 non-recurring fair value measurement [Abstract]
Discount to appraised value	20.80%	20.80%
Home equity lines and loans | Other real estate owned: | Non-recurring | Sales comparison | Weighted Average
Information related to Level 3 non-recurring fair value measurement [Abstract]
Discount to appraised value	20.80%	20.80%