FEDERAL HOME LOAN BANK ADVANCES - Contractual Maturities and Weighted Average Interest Rates of FHLB Advances (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Contractual Maturity, Amount
Overnight	$ 195,000
Due within a year	240,000	$ 240,433
Total FHLB advances	$ 435,000	$ 240,433
Weighted Average Rate
Overnight (as a percent)	1.81%
2019		2.72%
2020	1.84%
Weighted Average Rate for total FHLB advances (as a percent)	1.82%	2.72%