EMPLOYEE BENEFIT PLAN - SERP (Details) - Supplemental Retirement Plan ('SERP') - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 27,520,000		$ 27,520,000		$ 28,476,000
Trading gains (losses), net	$ 4,029,000	$ 785,000	$ (958,000)	$ 3,636,000