DERIVATIVES - Interest Rate Swaps Designated as Cash Flow Hedges (Details) - Interest rate swaps - Derivative designated as a cash flow hedge - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Derivatives
Notional amounts	$ 290,000	$ 240,000
Weighted average pay rates (as a percent)	1.82%	1.84%
Weighted average receive rates (as a percent)	2.39%	2.77%
Weighted average maturity	2 years 3 months 18 days	2 years 11 days