NOTES PAYABLE TO BANKS - Interest incurred including facility fees on unused portion of revolving credit facility and amortization of loan costs (Details) - Revolving credit facility - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Line of Credit Facility [Line Items]
Interest incurred	$ 89	$ 103
Interest paid	$ 62	$ 62