REAL ESTATE AND RELATED LEASE INTANGIBLES, NET - Schedule of Real Estate Properties Acquired (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Purchase Price	$ 122,707	$ 236,932	$ 62,495
Diversified | Lithia Springs, GA
Business Acquisition [Line Items]
Purchase Price	$ 24,466
Ownership Interest (percent)	70.60%
Diversified | Lithia Springs, GA | Consolidated Joint Venture
Business Acquisition [Line Items]
Purchase Price	$ 2,900
Diversified | Isla Vista, CA
Business Acquisition [Line Items]
Purchase Price	$ 85,087
Ownership Interest (percent)	75.00%
Diversified | Isla Vista, CA | Consolidated Joint Venture
Business Acquisition [Line Items]
Purchase Price	$ 4,600
Diversified | Peoria, IL
Business Acquisition [Line Items]
Purchase Price			$ 2,760
Ownership Interest (percent)			100.00%
Diversified | El Monte, CA
Business Acquisition [Line Items]
Purchase Price		$ 54,110
Ownership Interest (percent)		70.00%
Diversified | El Monte, CA | Consolidated Joint Venture
Business Acquisition [Line Items]
Purchase Price		$ 5,300
Diversified | Miami, FL
Business Acquisition [Line Items]
Purchase Price		$ 38,145
Ownership Interest (percent)		80.00%
Diversified | Miami, FL | Consolidated Joint Venture
Business Acquisition [Line Items]
Purchase Price		$ 1,600
Diversified | Crum Lynne, PA
Business Acquisition [Line Items]
Purchase Price		$ 9,196
Ownership Interest (percent)		100.00%
Diversified | Ewing, NJ
Business Acquisition [Line Items]
Purchase Price			$ 30,640
Ownership Interest (percent)			100.00%
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 | Ogden, IA
Business Acquisition [Line Items]
Purchase Price	$ 1,137
Ownership Interest (percent)	100.00%
Net Lease | New Hampton, IA
Business Acquisition [Line Items]
Purchase Price	$ 1,317
Ownership Interest (percent)	100.00%
Net Lease | Pinconning, MI
Business Acquisition [Line Items]
Purchase Price	$ 1,235
Ownership Interest (percent)	100.00%
Net Lease | Bolivar, MO
Business Acquisition [Line Items]
Purchase Price	$ 1,175
Ownership Interest (percent)	100.00%
Net Lease | Carthage, MO
Business Acquisition [Line Items]
Purchase Price	$ 1,099
Ownership Interest (percent)	100.00%
Net Lease | Pelican Rapids, MN
Business Acquisition [Line Items]
Purchase Price	$ 1,196
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%
Net Lease | Milford, IA
Business Acquisition [Line Items]
Purchase Price		$ 1,298
Ownership Interest (percent)		100.00%
Net Lease | Kawkawlin, MI
Business Acquisition [Line Items]
Purchase Price		$ 1,234
Ownership Interest (percent)		100.00%
Net Lease | Aroma Park, IL
Business Acquisition [Line Items]
Purchase Price		$ 1,218
Ownership Interest (percent)		100.00%
Net Lease | East Peoria, IL
Business Acquisition [Line Items]
Purchase Price		$ 1,350
Ownership Interest (percent)		100.00%
Net Lease | Winterset, IA
Business Acquisition [Line Items]
Purchase Price		$ 1,258
Ownership Interest (percent)		100.00%
Net Lease | Rockford, MN
Business Acquisition [Line Items]
Purchase Price		$ 1,195
Ownership Interest (percent)		100.00%
Net Lease | Dimmitt, TX
Business Acquisition [Line Items]
Purchase Price			$ 1,319
Ownership Interest (percent)			100.00%
Net Lease | Philo, IL
Business Acquisition [Line Items]
Purchase Price			$ 1,156
Ownership Interest (percent)			100.00%
Net Lease | St. Charles, MN
Business Acquisition [Line Items]
Purchase Price			$ 1,198
Ownership Interest (percent)			100.00%
Net Lease | San Antonio, TX
Business Acquisition [Line Items]
Purchase Price			$ 1,096
Ownership Interest (percent)			100.00%
Net Lease | Borger, TX
Business Acquisition [Line Items]
Purchase Price			$ 978
Ownership Interest (percent)			100.00%
Net Lease | Champaign, IL
Business Acquisition [Line Items]
Purchase Price			$ 1,324
Ownership Interest (percent)			100.00%
Net Lease | Decatur-Sunnyside, IL
Business Acquisition [Line Items]
Purchase Price			$ 1,181
Ownership Interest (percent)			100.00%
Net Lease | Flora Vista, NM
Business Acquisition [Line Items]
Purchase Price			$ 1,305
Ownership Interest (percent)			100.00%
Net Lease | Mountain Grove, MO
Business Acquisition [Line Items]
Purchase Price			$ 1,279
Ownership Interest (percent)			100.00%
Net Lease | Rantoul, IL
Business Acquisition [Line Items]
Purchase Price			$ 1,204
Ownership Interest (percent)			100.00%
Net Lease | Decatur-Pershing, IL
Business Acquisition [Line Items]
Purchase Price			$ 1,365
Ownership Interest (percent)			100.00%
Net Lease | Cape Girardeau, MO
Business Acquisition [Line Items]
Purchase Price			$ 1,281
Ownership Interest (percent)			100.00%
Net Lease | Linn, MO
Business Acquisition [Line Items]
Purchase Price			$ 1,122
Ownership Interest (percent)			100.00%
Net Lease | Union, MO
Business Acquisition [Line Items]
Purchase Price			$ 1,227
Ownership Interest (percent)			100.00%
Net Lease | Pawnee, IL
Business Acquisition [Line Items]
Purchase Price			$ 1,201
Ownership Interest (percent)			100.00%
Net Lease | Lamar, MO
Business Acquisition [Line Items]
Purchase Price			$ 1,176
Ownership Interest (percent)			100.00%
Net Lease | Dryden Township, MI
Business Acquisition [Line Items]
Purchase Price			$ 1,190
Ownership Interest (percent)			100.00%
Net Lease | Fayetteville, NC
Business Acquisition [Line Items]
Purchase Price			$ 6,971
Ownership Interest (percent)			100.00%
Net Lease | Springfield, IL
Business Acquisition [Line Items]
Purchase Price			$ 1,322
Ownership Interest (percent)			100.00%
Land | St. Paul, MN
Business Acquisition [Line Items]
Purchase Price			$ 200
Ownership Interest (percent)			100.00%