FEDERAL HOME LOAN BANK ADVANCES - Contractual Maturities and Weighted Average Interest Rates of FHLB Advances (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Contractual Maturity, Amount
Overnight	$ 90,000
2019	240,217	$ 240,433
Total FHLB advances	$ 330,217	$ 240,433
Weighted Average Rate
Overnight (as a percent)	2.66%
2019 (as a percent)	2.68%	2.72%
Weighted Average Rate for total FHLB advances (as a percent)	2.67%	2.72%