GOODWILL AND INTANGIBLE ASSETS - Estimated annual amortization expense of core deposit intangibles (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Goodwill and Intangible Assets Disclosure [Abstract]
CDI amortization	$ 58	$ 154	$ 154	$ 196	$ 222	$ 222	$ 222	$ 222