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SALES OF PROPERTIES (Details)												12 Months Ended
	Dec. 15, 2020 USD ($) property	Jul. 01, 2020 USD ($)	Feb. 11, 2020 USD ($)	Dec. 10, 2019 USD ($)	Oct. 21, 2019 USD ($)	Aug. 29, 2019 USD ($)	Aug. 23, 2019 USD ($)	Jun. 20, 2019 USD ($)	Dec. 13, 2018 USD ($)	Sep. 14, 2018 USD ($)	Jan. 30, 2018 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Nov. 30, 2017 USD ($)
Sale of Property
Gross Sales Price												$ 34,340,000	$ 41,891,000	$ 27,659,000
Gain (Loss) on Sale of Real Estate, Net												17,280,000	4,327,000	5,262,000
Mortgage Prepaid on Sale												11,815,000	17,507,000	$ 4,423,000
Prepayment costs on debt related to real estate												1,123,000	$ 827,000
Hobby Lobby retail property, Onalaska, Wisconsin
Sale of Property
Gross Sales Price			$ 7,115,000
Gain (Loss) on Sale of Real Estate, Net			4,252,000
Mortgage Prepaid on Sale			3,332,000
Prepayment costs on debt related to real estate			$ 290,000
CarMax retail property, Knoxville, Tennessee
Sale of Property
Gross Sales Price		$ 18,000,000
Gain (Loss) on Sale of Real Estate, Net		10,316,000
Mortgage Prepaid on Sale		8,483,000
Prepayment costs on debt related to real estate		$ 833,000
Pet Smart and Guitar Center retail properties, Houston, Texas
Sale of Property
Number of properties sold | property	2
Gross Sales Price	$ 9,225,000
Seller-financing provided by the Company												$ 4,613,000
Loan receivable interest rate	4.0
Pet Smart retail property, Houston, Texas
Sale of Property
Gross Sales Price	4,013,000
Gain (Loss) on Sale of Real Estate, Net	1,067,000
Guitar Center retail property, Houston, Texas
Sale of Property
Gross Sales Price	5,212,000
Gain (Loss) on Sale of Real Estate, Net	$ 1,645,000
Kmart retail property, Clemmons, North Carolina
Sale of Property
Gross Sales Price								$ 5,500,000
Gain (Loss) on Sale of Real Estate, Net								1,099,000
Mortgage Prepaid on Sale								1,705,000
Prepayment costs on debt related to real estate								$ 41,000
Multi-tenant retail property, Athens, Georgia
Sale of Property
Gross Sales Price							$ 6,050,000
Gain (Loss) on Sale of Real Estate, Net							1,045,000
Mortgage Prepaid on Sale							2,645,000
Prepayment costs on debt related to real estate							$ 161,000
Land - The Briarbrook Village Apartments, Wheaton, Illinois
Sale of Property
Gross Sales Price						$ 12,066,000
Gain (Loss) on Sale of Real Estate, Net						$ 1,530,000
Aaron's retail property, Houston, Texas
Sale of Property
Gross Sales Price					$ 1,675,000
Gain (Loss) on Sale of Real Estate, Net					$ 218,000
Assisted living facility, Round Rock, Texas
Sale of Property
Gross Sales Price				$ 16,600,000
Gain (Loss) on Sale of Real Estate, Net				435,000
Mortgage Prepaid on Sale				13,157,000
Prepayment costs on debt related to real estate				$ 625,000
Multi-tenant retail property, Fort Bend, Texas
Sale of Property
Gross Sales Price											$ 9,200,000
Gain (Loss) on Sale of Real Estate, Net											2,408,000
Mortgage Prepaid on Sale											$ 4,423,000
Land - The Meadows Apartments, Lakemoor, Illinois
Sale of Property
Gross Sales Price										$ 8,459,000
Gain (Loss) on Sale of Real Estate, Net										4,585,000
Unamortized balance, fixed rent										$ 5,717,000
Deferred income															$ 5,906,000
Shopko retail property, Lincoln, Nebraska
Sale of Property
Gross Sales Price									$ 10,000,000
Gain (Loss) on Sale of Real Estate, Net									$ (1,731,000)
Consolidated Joint Venture | Kmart retail property, Clemmons, North Carolina
Sale of Property
Ownership interest in consolidated joint venture of the company (as a percent)								90.00%
Non-controlling interest's share of the gain								$ 422,000
Consolidated Joint Venture | Multi-tenant retail property, Fort Bend, Texas
Sale of Property
Ownership interest in consolidated joint venture of the company (as a percent)											85.00%
Non-controlling interest's share of the gain											$ 776,000

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