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RELATED PARTY TRANSACTIONS - Other (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Chairman | General and administrative expense
RELATED PARTY TRANSACTIONS
Fees under compensation and services agreement	$ 289,000	$ 276,000	$ 276,000
Vice Chairman | General and administrative expense
RELATED PARTY TRANSACTIONS
Fees under compensation and services agreement	$ 116,000	$ 110,000	110,000
Gould Investors L.P.
RELATED PARTY TRANSACTIONS
Number of common stock shares owned by the related party	1,785,976	1,785,976
Ownership percentage held by the related party	9.00%	9.20%
Amount of insurance reimbursed	$ 1,025,000	$ 912,000	790,000
Gould Investors L.P. | Real estate expenses
RELATED PARTY TRANSACTIONS
Insurance expense recognized of amounts reimbursed to related party	$ 927,000	$ 877,000	$ 757,000

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