REAL ESTATE AND RELATED LEASE INTANGIBLES, NET - Schedule of Real Estate Properties Acquired (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Business Acquisition [Line Items]
Purchase Price	$ 230,677	$ 50,252
Land | St. Paul, MN
Business Acquisition [Line Items]
Purchase Price		$ 200
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 | 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 | 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%
Other | El Monte, CA
Business Acquisition [Line Items]
Purchase Price	$ 54,110
Ownership Interest (percent)	70.00%
Other | Jacksonville, FL
Business Acquisition [Line Items]
Purchase Price	$ 115,641
Ownership Interest (percent)	100.00%
Other | Miami, FL
Business Acquisition [Line Items]
Purchase Price	$ 38,145
Ownership Interest (percent)	80.00%
Other | Crum Lynne, PA
Business Acquisition [Line Items]
Purchase Price	$ 9,196
Ownership Interest (percent)	100.00%
Other | Ewing, NJ
Business Acquisition [Line Items]
Purchase Price		$ 30,640
Ownership Interest (percent)		100.00%
Consolidated Joint Venture | Other | El Monte, CA
Business Acquisition [Line Items]
Purchase Price	$ 5,300
Consolidated Joint Venture | Other | Miami, FL
Business Acquisition [Line Items]
Purchase Price	$ 1,600