LOANS - Troubled debt restructurings (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) Integer	Dec. 31, 2016 USD ($) Integer
Residential real estate
Quantity of troubled debt restructurings | Integer	1	5
Pre-modification balance	$ 222	$ 772
Post-modification balance	$ 222	$ 772
Business Activities Loans - Residential real estate - Land
Quantity of troubled debt restructurings | Integer
Pre-modification balance
Post-modification balance
Commercial and industrial
Quantity of troubled debt restructurings | Integer	1	2
Pre-modification balance	$ 600	$ 2,123
Post-modification balance	$ 600	$ 2,123
Business Activities Loans - Commercial real estate - Construction of commercial
Quantity of troubled debt restructurings | Integer
Pre-modification balance
Post-modification balance
Business Activities Loans - Commercial real estate - Consumer
Quantity of troubled debt restructurings | Integer
Pre-modification balance
Post-modification balance
Business Activities Loans - Commercial and industrial
Quantity of troubled debt restructurings | Integer	2
Pre-modification balance	$ 182
Post-modification balance	$ 182
Business Activities Loans - HELOC
Quantity of troubled debt restructurings | Integer
Pre-modification balance
Post-modification balance
Totals
Quantity of troubled debt restructurings | Integer	4	7
Pre-modification balance	$ 1,004	$ 2,895
Post-modification balance	$ 1,004	$ 2,895
Business Activities Loans - Rate reduction and term extension
Quantity of troubled debt restructurings | Integer	3	2
Pre-modification balance	$ 404	$ 262
Post-modification balance	$ 404	$ 262
Business Activities Loans - Debt consolidation and term extension
Quantity of troubled debt restructurings | Integer		1
Pre-modification balance		$ 260
Post-modification balance		$ 260
Business Activities Loans - Debt consolidation
Quantity of troubled debt restructurings | Integer		1
Pre-modification balance		$ 1,863
Post-modification balance		$ 1,863
Business Activities Loans - Term extension
Quantity of troubled debt restructurings | Integer	1	3
Pre-modification balance	$ 600	$ 510
Post-modification balance	$ 600	$ 510