CREDIT FACILITY (Narrative) (Details) - Unsecured Revolving Credit Facility [Member] - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	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, amount outstanding	$ 0		$ 0		$ 0
Revolving credit facility, borrowing capacity, maximum						$ 50,000,000
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	$ 0
Revolving credit facility, commitment fees, classified within interest (expense) income, net	32,000	$ 32,000	95,000	$ 95,000
Revolving credit facility, unamortized debt issuance costs	$ 10,000		$ 10,000
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%