REAL ESTATE PROPERTIES HELD FOR INVESTMENT - Narrative (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) Customer Property acquisition	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Real Estate Properties [Line Items]
Change in fair value of contingent consideration	$ 1,526,000	$ 1,550,000	$ 1,560,000
Security deposit liability	2,700,000	1,300,000
Reserve for unpaid cash rents	3,200,000	3,500,000
Reserve associated with straight-line rental income	$ 3,700,000	$ 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	32.30%
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Holiday [Member]
Real Estate Properties [Line Items]
Concentration risk percent	16.20%
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | NMS [Member]
Real Estate Properties [Line Items]
Concentration risk percent	12.40%
Minimum [Member]
Real Estate Properties [Line Items]
Operating lease expiration period	4 years
Maximum [Member]
Real Estate Properties [Line Items]
Operating lease expiration period	16 years
Weighted Average [Member]
Real Estate Properties [Line Items]
Operating lease expiration period	9 years
Accounts Payable and Accrued Liabilities [Member]
Real Estate Properties [Line Items]
Contingent consideration liability	$ 800,000
Genesis [Member]
Real Estate Properties [Line Items]
Number of properties marketed | Property	35
Number of properties remaining | Property	43
Acquisitions With Contingent Consideration Arrangements [Member]
Real Estate Properties [Line Items]
Number of real estate acquisitions | acquisition	4
Estimated earn-out value	$ 3,200,000
Contingent consideration asset	$ 0