CREDIT FACILITY (Narrative) (Details) - Unsecured Revolving Credit Facility [Member] - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Nov. 06, 2015
Line Of Credit Facility [Line Items]
Revolving credit facility, initiation date (Date)	Nov. 06, 2015
Revolving credit facility, expiration date (Date)	Nov. 06, 2020
Revolving credit facility, borrowing capacity, maximum				$ 50,000,000
Revolving credit facility, amount outstanding	$ 0	$ 0
Amount above Federal Funds rate, used as base rate, if higher than prime and LIBOR plus 1.50% (in Percent)	0.50%
Amount above one month LIBOR rate as determine three days prior, used as base rate, if higher than prime or federal funds rate plus 0.50% (in Percent)	1.50%
Revolving credit facility, unused commitment fee annual percentage (in Percent)	0.25%
Revolving credit facility, interest on borrowed funds	$ 0	0	$ 0
Revolving credit facility, commitment fee	127,000	$ 127,000	$ 118,000
Revolving credit facility, unamortized debt issuance costs	$ 13,000
Base Rate [Member] | Minimum [Member]
Line Of Credit Facility [Line Items]
Revolving credit facility, basis spread on variable rate (in Percent)	0.00%
Base Rate [Member] | Maximum [Member]
Line Of Credit Facility [Line Items]
Revolving credit facility, basis spread on variable rate (in Percent)	0.50%
London Interbank Offered Rate "LIBOR" [Member] | Minimum [Member]
Line Of Credit Facility [Line Items]
Revolving credit facility, basis spread on variable rate (in Percent)	1.25%
London Interbank Offered Rate "LIBOR" [Member] | Maximum [Member]
Line Of Credit Facility [Line Items]
Revolving credit facility, basis spread on variable rate (in Percent)	1.75%