INVESTMENT SECURITIES - Narrative (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018 USD ($) security	Dec. 31, 2018 USD ($) security	Dec. 31, 2017 USD ($)
Investments, Debt and Equity Securities [Abstract]
Number of securities in unrealized loss positions | security	107	107
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Transfer of held-to-maturity securities to available-for-sale		$ 23,945	$ 0
Securities pledged as collateral for public funding	$ 162,500	162,500	$ 177,900
ASU 2017-12
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Transfer of held-to-maturity securities to available-for-sale	23,900	$ 23,900
Transfer of held-to-maturity securities to available-for-sale, fair value	$ 24,000