REAL ESTATE PROPERTIES 4 (Details)	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
State or Province [Line Items]
Leases terms minimum (in years)	40 years
Leases terms maximum (in years)	50 years
Renewal period option minimum (in years)	15 years
Renewal period option maximum (in years)	35 years
Total ground lease expenditures for continuing and discontinued operations	$ 760,000	$ 756,000	$ 756,000
Payment increase interval minimum (in years)	3 years
Payment increase interval maximum (in years)	10 years
Future Total Minimum Ground Lease Payments [Abstract]
2018	$ 761,000
2019	761,000
2020	761,000
2021	761,000
2022	761,000
Thereafter	9,729,000
Total minimum payments	$ 13,534,000
ARIZONA
State or Province [Line Items]
Number of properties subject to ground leases	1
TEXAS
State or Province [Line Items]
Number of properties subject to ground leases	2
FLORIDA
State or Province [Line Items]
Number of properties subject to ground leases	2