INCOME PROPERTY PORTFOLIO - General Information (Details) ft² in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2020 USD ($) ft² property	Jun. 30, 2020 USD ($) ft² property	Jun. 30, 2019 USD ($)
Acquisitions of Income Properties
Number of real estate properties | property	31	31
Payments to Acquire Commercial Real Estate	$ 28,600,000
Area of real estate property | ft²	1,350	1,350
Number of properties sold	0	0
Amount allocated of total acquisition cost
Weighted average amortization period of intangible liabilities		8 years 7 months 6 days
2020 acquisitions of income property subject to lease
Acquisitions of Income Properties
Number of real estate properties	11	11
Payments to Acquire Commercial Real Estate		$ 75,400,000
Aggregate acquisition cost including capitalized acquisition costs		76,000,000
Land	$ 22,500,000	22,500,000
Buildings and improvements	42,200,000	42,200,000
Intangible assets pertaining to the in-place lease value, leasing fees and above market lease value	12,400,000	12,400,000
Intangible liabilities for below market lease value	$ 1,100,000	$ 1,100,000
Amount allocated of total acquisition cost
Weighted average amortization period of intangible liabilities		9 years 3 months 18 days
2019 acquisitions of income property subject to lease
Acquisitions of Income Properties
Number of real estate properties			4
Payments to Acquire Commercial Real Estate			$ 19,300,000
Aggregate acquisition cost including capitalized acquisition costs			19,500,000
Land			9,000,000
Buildings and improvements			9,000,000
Intangible assets pertaining to the in-place lease value, leasing fees and above market lease value			1,900,000
Intangible liabilities for below market lease value			$ 400,000
Number of properties sold			0
Amount allocated of total acquisition cost
Weighted average amortization period of intangible liabilities			10 years 4 months 24 days