REAL ESTATE PROPERTIES HELD FOR INVESTMENT - Narrative (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2016 USD ($) Customer	Jun. 30, 2016 USD ($) acquisition Customer	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Real Estate Properties [Line Items]
Number of acquired properties | acquisition		4
Estimated earn-out value	$ 3,200	$ 3,200
Contingent consideration asset	0	0
Change in fair value of contingent consideration	50	$ 50	$ (200)
Weighted average lease expiration period		9 years
Security deposit liability	1,600	$ 1,600		$ 1,300
Reserve for unpaid cash rents	3,500	3,500		3,500
Allowance for straight-line rental income	$ 1,300	$ 1,300		$ 5,300
Sales Revenue, Net [Member] | Customer Concentration Risk [Member]
Real Estate Properties [Line Items]
Number of major customers | Customer	3	3
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Genesis [Member]
Real Estate Properties [Line Items]
Concentration risk percent		33.60%
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Holiday [Member]
Real Estate Properties [Line Items]
Concentration risk percent		16.60%
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | NMS [Member]
Real Estate Properties [Line Items]
Concentration risk percent		10.40%
Minimum [Member]
Real Estate Properties [Line Items]
Lease expiration period		1 year
Maximum [Member]
Real Estate Properties [Line Items]
Lease expiration period		16 years
Accounts Payable and Accrued Liabilities [Member]
Real Estate Properties [Line Items]
Contingent consideration liability	$ 2,300	$ 2,300