OTHER REAL ESTATE OWNED - Summary of Activity in Purchased Other Real Estate Owned (Details) - Purchased other real estate owned - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Purchased Other Real Estate [Roll Forward]
Balance, January 1	$ 12,540	$ 19,344
Loans transferred to other real estate owned	5,023	7,229
Acquired in acquisitions	0	1,927
Portion of gains (losses) on sale and write-downs payable to (receivable from) the FDIC under loss-sharing agreements	86	0
Net gains (losses) on sale and write-downs recorded in statement of income	362	(615)
Sales proceeds	(9,000)	(15,345)
Ending balance	$ 9,011	$ 12,540