LONG-TERM DEBT - Mortgage Notes Payable (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($) property building
Long-term debt
Face amount of debt	$ 173,300
Number of income properties securing debt | property	6
UBS Mortgage Note Payable
Long-term debt
Number of buildings securing debt | building	2
Face amount of debt	$ 7,300
Interest rate on mortgage loan	3.655%
Wells Fargo Mortgage Note Payable Originated September 30, 2014
Long-term debt
Face amount of debt	$ 30,000
Number of income properties securing debt | property	6
Interest rate on mortgage loan	4.33%
Period of fixed interest rate	10 years
Period of interest only payments	10 years
Period to when loan is pre-payable	10 years
Wells Fargo Mortgage Note Payable Originated April 15, 2016
Long-term debt
Face amount of debt	$ 25,000
Period of interest only payments	2 years
Period of amortization for principal payments	25 years
Term of mortgage loan	5 years
Fixed interest rate through use of interest rate swap (as a percent)	3.17%
Wells Fargo Mortgage Note Payable Originated April 15, 2016 | LIBOR
Long-term debt
Margin added to variable rate basis (as a percent)	1.90%