REAL ESTATE AND RELATED LEASE INTANGIBLES, NET - Schedule of Real Estate Properties Acquired (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Business Acquisition [Line Items]
Purchase Price	$ 114,184	$ 182,038
Diversified | Lithia Springs, GA
Business Acquisition [Line Items]
Purchase Price	$ 24,466
Ownership Interest (percent)	70.60%
Diversified | Isla Vista, CA
Business Acquisition [Line Items]
Purchase Price	$ 83,723
Ownership Interest (percent)	75.00%
Diversified | El Monte, CA
Business Acquisition [Line Items]
Purchase Price		$ 54,110
Ownership Interest (percent)		70.00%
Net Lease | Kirbyville, MO
Business Acquisition [Line Items]
Purchase Price	$ 1,156
Ownership Interest (percent)	100.00%
Net Lease | Gladwin, MI
Business Acquisition [Line Items]
Purchase Price	$ 1,171
Ownership Interest (percent)	100.00%
Net Lease | Foley, MN
Business Acquisition [Line Items]
Purchase Price	$ 1,176
Ownership Interest (percent)	100.00%
Net Lease | Moscow Mills, MO
Business Acquisition [Line Items]
Purchase Price	$ 1,237
Ownership Interest (percent)	100.00%
Net Lease | Wonder Lake, IL
Business Acquisition [Line Items]
Purchase Price	$ 1,255
Ownership Interest (percent)	100.00%
Net Lease | Carmi, IL
Business Acquisition [Line Items]
Purchase Price		$ 1,411
Ownership Interest (percent)		100.00%
Net Lease | Peoria, IL
Business Acquisition [Line Items]
Purchase Price		$ 1,183
Ownership Interest (percent)		100.00%
Net Lease | Ridgedale, MO
Business Acquisition [Line Items]
Purchase Price		$ 1,298
Ownership Interest (percent)		100.00%
Net Lease | Hanna City, IL
Business Acquisition [Line Items]
Purchase Price		$ 1,141
Ownership Interest (percent)		100.00%
Net Lease | Jessup, IA
Business Acquisition [Line Items]
Purchase Price		$ 1,163
Ownership Interest (percent)		100.00%
Net Lease | Shelbyville, IL
Business Acquisition [Line Items]
Purchase Price		$ 1,132
Ownership Interest (percent)		100.00%
Net Lease | Jacksonville, FL
Business Acquisition [Line Items]
Purchase Price		$ 115,641
Ownership Interest (percent)		100.00%
Net Lease | Wabasha, MN
Business Acquisition [Line Items]
Purchase Price		$ 1,280
Ownership Interest (percent)		100.00%
Net Lease | Port O'Connor, TX
Business Acquisition [Line Items]
Purchase Price		$ 1,255
Ownership Interest (percent)		100.00%
Net Lease | Denver, IA
Business Acquisition [Line Items]
Purchase Price		$ 1,183
Ownership Interest (percent)		100.00%
Net Lease | Jefferson City, MO
Business Acquisition [Line Items]
Purchase Price		$ 1,241
Ownership Interest (percent)		100.00%
Consolidated Joint Venture | Diversified | El Monte, CA
Business Acquisition [Line Items]
Purchase Price		$ 5,300