INCOME PROPERTIES AND LEASES - Properties Acquired (Details)	6 Months Ended
	Jun. 30, 2020 USD ($) ft²	Jun. 30, 2019 USD ($) ft²
Acquisitions of Income Properties
Square-Feet | ft²	522,681	139,514
Purchase price	$ 137,235,000	$ 40,559,000
Remaining Lease Term	4 years 2 months 12 days	9 years 6 months
2019 acquisitions of income property subject to lease
Acquisitions of Income Properties
Purchase price		$ 40,600,000
2020 acquisitions of income property subject to lease
Acquisitions of Income Properties
Purchase price	$ 137,200,000
Winston-Salem, NC | 2020 acquisitions of income property subject to lease
Acquisitions of Income Properties
Square-Feet | ft²	254,109
Purchase price	$ 61,800,000
Percentage Leased	99.00%
Remaining Lease Term	5 years
Winston-Salem, NC | 2019 acquisitions of income property subject to lease - Hobby Lobby Stores, Inc
Acquisitions of Income Properties
Square-Feet | ft²		55,000
Purchase price		$ 8,075,000
Percentage Leased		100.00%
Remaining Lease Term		10 years 10 months 24 days
Falls Church, VA | 2020 acquisitions of income property subject to lease
Acquisitions of Income Properties
Square-Feet | ft²	268,572
Purchase price	$ 75,435,000
Percentage Leased	80.00%
Remaining Lease Term	3 years 7 months 6 days
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
Purchase price		$ 21,250,000
Percentage Leased		100.00%
Remaining Lease Term		8 years 7 months 6 days
Birmingham, AL | 2019 acquisitions of income property subject to lease - Walgreen Co.
Acquisitions of Income Properties
Square-Feet | ft²		14,516
Purchase price		$ 5,500,000
Percentage Leased		100.00%
Remaining Lease Term		9 years 9 months 18 days
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
Purchase price		$ 2,100,000
Percentage Leased		100.00%
Remaining Lease Term		4 years 9 months 18 days
Albany, GA | 2019 acquisitions of income property subject to lease - Walgreen Co.
Acquisitions of Income Properties
Square-Feet | ft²		14,770
Purchase price		$ 3,634,000
Percentage Leased		100.00%
Remaining Lease Term		13 years 7 months 6 days