INCOME PROPERTIES - Properties Acquired (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) ft² a
Acquisitions of Income Properties
Square-Feet | ft²	502,626
Purchase price	$ 164,670
Winston-Salem, NC | 2019 acquisitions of income property subject to lease - Hobby Lobby Stores, Inc
Acquisitions of Income Properties
Square-Feet | ft²	55,000
Area of land (in acres) | a	7.60
Purchase price	$ 8,075
Percentage Leased	100.00%
Falls Church, VA | 2019 acquisitions of income property subject to lease - 24 Hour Fitness USA, Inc
Acquisitions of Income Properties
Square-Feet | ft²	46,000
Area of land (in acres) | a	3.10
Purchase price	$ 21,250
Percentage Leased	100.00%
Birmingham, AL | 2019 acquisitions of income property subject to lease - Walgreen Co.
Acquisitions of Income Properties
Square-Feet | ft²	14,516
Area of land (in acres) | a	2.10
Purchase price	$ 5,500
Percentage Leased	100.00%
Lynn, MA | 2019 acquisitions of income property subject to lease - Family Dollar Stores of Massachusetts, Inc
Acquisitions of Income Properties
Square-Feet | ft²	9,228
Area of land (in acres) | a	0.70
Purchase price	$ 2,100
Percentage Leased	100.00%
Albany, GA | 2019 acquisitions of income property subject to lease - Walgreen Co.
Acquisitions of Income Properties
Square-Feet | ft²	14,770
Area of land (in acres) | a	3.60
Purchase price	$ 3,634
Percentage Leased	100.00%
Austin, TX | 2019 acquisitions of income property subject to lease - Carpenter Hotel
Acquisitions of Income Properties
Area of land (in acres) | a	1.40
Purchase price	$ 16,250
Percentage Leased	100.00%
Reston, VA | 2019 acquisitions of income property subject to lease - General Dynamics Corporation
Acquisitions of Income Properties
Square-Feet | ft²	64,319
Area of land (in acres) | a	3.00
Purchase price	$ 18,600
Percentage Leased	100.00%
East Troy, WI | 2019 acquisitions of income property subject to lease - Live Nation Entertainment, Inc.
Acquisitions of Income Properties
Area of land (in acres) | a	158.30
Purchase price	$ 7,500
Percentage Leased	100.00%
Oceanside, NY | 2019 acquisitions of income property subject to lease - Party City Corporation
Acquisitions of Income Properties
Square-Feet | ft²	15,500
Area of land (in acres) | a	1.20
Purchase price	$ 7,120
Percentage Leased	100.00%
N. Richland Hills, TX | 2019 acquisitions of income property subject to lease - Burlington Stores, Inc.
Acquisitions of Income Properties
Square-Feet | ft²	70,891
Area of land (in acres) | a	5.30
Purchase price	$ 11,940
Percentage Leased	100.00%
Jacksonville, FL | 2019 acquisitions of income property subject to lease - The Strand
Acquisitions of Income Properties
Square-Feet | ft²	212,402
Area of land (in acres) | a	52.00
Purchase price	$ 62,701
Percentage Leased	95.00%