GOODWILL AND INTANGIBLE ASSETS - Estimated annual amortization expense of core deposit intangibles (Details) (Estimated annual amortization expense of core deposit intangibles, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Estimated annual amortization expense of core deposit intangibles
Core deposit intangibles amortization	$ 66	$ 154	$ 154	$ 202