INTEREST RATE SWAPS - CASH FLOW HEDGES (Details) - Interest rate swap - Cash flow hedge $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2013 DerivativeInstrument
Information about derivatives and swaps
Number of derivative agreements | DerivativeInstrument			2
Summary information about interest rate swaps
Notional amount	$ 20,000
Assets / (Liabilities)	26	$ 115
Unrealized Gain (Loss) in AOCI	20	90
1-month LIBOR
Summary information about interest rate swaps
Notional amount	$ 10,000
Pay rate (as a percent)	2.17%
Assets / (Liabilities)	$ 16	58
Unrealized Gain (Loss) in AOCI	12	45
3-month LIBOR
Summary information about interest rate swaps
Notional amount	$ 10,000
Pay rate (as a percent)	2.33%
Assets / (Liabilities)	$ 10	57
Unrealized Gain (Loss) in AOCI	$ 8	$ 45