LOANS AND ALLOWANCE FOR LOAN LOSSES - Internal Risk Rating (Details)	12 Months Ended
	Dec. 31, 2017 USD ($) category
Average recorded investment in impaired loans and related interest income recognized
Number of points in internal risk rating system	9
Number of categories in internal risk rating system considered as not criticized	6
Commercial relationship credit review threshold amount | $	$ 1,000,000
Past due period before loans placed in non-accrual status	90 days
Recent loan payment history before removal from non-accrual status	6 months