REAL ESTATE PROPERTIES HELD FOR INVESTMENT - Narrative (Details)	3 Months Ended
	Mar. 31, 2016 USD ($) acquisition Customer	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)
Real Estate Properties [Line Items]
Number of acquired properties | acquisition	4
Estimated earn-out value	$ 3,200,000
Change in fair value of contingent consideration	$ 0	$ (100,000)
Weighted average lease expiration period	10 years
Security deposit liability	$ 1,400,000		$ 1,300,000
Reserve for unpaid cash rents	3,500,000		3,500,000
Allowance for straight-line rental income	$ 5,500,000		$ 5,300,000
Sales Revenue, Net [Member] | Customer Concentration Risk [Member]
Real Estate Properties [Line Items]
Number of major customers | Customer	3
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Genesis [Member]
Real Estate Properties [Line Items]
Concentration risk percent	33.90%
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Holiday [Member]
Real Estate Properties [Line Items]
Concentration risk percent	16.70%
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	17 years
Accounts Payable and Accrued Liabilities [Member]
Real Estate Properties [Line Items]
Contingent consideration liability	$ 2,700,000
Prepaid expenses, deferred financing costs and other assets, net [Member]
Real Estate Properties [Line Items]
Contingent consideration asset	$ 300,000