REAL ESTATE HELD FOR INVESTMENT (Schedule of Real Estate Investments) (Details) $ in Thousands			12 Months Ended
	Jan. 08, 2019 USD ($) shares	Sep. 07, 2016 USD ($) unit	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 824,860	$ 591,026
Accumulated Depreciation and Amortization			(65,381)	(38,052)
Total Real Estate, Net			759,479	552,974
Subsidiary of Common Parent
Real Estate Properties [Line Items]
Interest rate on Class A non-voting preferred membership units		10.00%
Proceeds from sale of units		$ 800
Subsidiary of Common Parent | Preferred Class A-2
Real Estate Properties [Line Items]
Interest rate on Class A non-voting preferred membership units	10.00%
Proceeds from sale of units	$ 1,900
Non-voting preferred membership units sold | shares	1,927
Disposed of by Sale | Subsidiary of Common Parent
Real Estate Properties [Line Items]
Number of real estate units | unit		820
Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			175,317	141,950
Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			618,974	426,604
Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			30,569	$ 22,472
Total Richardson Portfolio
Real Estate Properties [Line Items]
Total Real Estate, at Cost			45,420
Accumulated Depreciation and Amortization			(11,273)
Total Real Estate, Net			34,147
Total Richardson Portfolio | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			6,244
Total Richardson Portfolio | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			39,176
Total Richardson Portfolio | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 0
Palisades Central I
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Nov. 23, 2011
Total Real Estate, at Cost			$ 13,295
Accumulated Depreciation and Amortization			(3,565)
Total Real Estate, Net			$ 9,730
Ownership %			90.00%
Palisades Central I | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 1,037
Palisades Central I | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			12,258
Palisades Central I | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 0
Palisades Central II
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Nov. 23, 2011
Total Real Estate, at Cost			$ 21,816
Accumulated Depreciation and Amortization			(5,486)
Total Real Estate, Net			$ 16,330
Ownership %			90.00%
Palisades Central II | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 810
Palisades Central II | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			21,006
Palisades Central II | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 0
Greenway I
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Nov. 23, 2011
Total Real Estate, at Cost			$ 2,708
Accumulated Depreciation and Amortization			(901)
Total Real Estate, Net			$ 1,807
Ownership %			90.00%
Greenway I | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 561
Greenway I | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			2,147
Greenway I | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 0
Greenway III
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Nov. 23, 2011
Total Real Estate, at Cost			$ 4,467
Accumulated Depreciation and Amortization			(1,321)
Total Real Estate, Net			$ 3,146
Ownership %			90.00%
Greenway III | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 702
Greenway III | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			3,765
Greenway III | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 0
Undeveloped Land
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Nov. 23, 2011
Total Real Estate, at Cost			$ 3,134
Accumulated Depreciation and Amortization			0
Total Real Estate, Net			$ 3,134
Ownership %			90.00%
Undeveloped Land | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 3,134
Undeveloped Land | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			0
Undeveloped Land | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 0
Park Highlands
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Dec. 30, 2011
Total Real Estate, at Cost			$ 34,167
Accumulated Depreciation and Amortization
Total Real Estate, Net			$ 34,167
Ownership %			100.00%
Park Highlands | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 34,167
Park Highlands | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			0
Park Highlands | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 0
Park Centre
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Mar. 28, 2013
Total Real Estate, at Cost			$ 37,703
Accumulated Depreciation and Amortization			(6,334)
Total Real Estate, Net			$ 31,369
Ownership %			100.00%
Park Centre | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 3,251
Park Centre | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			34,452
Park Centre | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 0
1180 Raymond
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Aug. 20, 2013
Total Real Estate, at Cost			$ 47,420
Accumulated Depreciation and Amortization			(7,897)
Total Real Estate, Net			$ 39,523
Ownership %			100.00%
1180 Raymond | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 8,292
1180 Raymond | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			39,128
1180 Raymond | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 0
Park Highlands II
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Dec. 10, 2013
Total Real Estate, at Cost			$ 27,078
Accumulated Depreciation and Amortization			0
Total Real Estate, Net			27,078
Park Highlands II | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			27,078
Park Highlands II | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			0
Park Highlands II | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 0
Richardson Land II
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Sep. 04, 2014
Total Real Estate, at Cost			$ 3,418
Accumulated Depreciation and Amortization			0
Total Real Estate, Net			$ 3,418
Ownership %			90.00%
Richardson Land II | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 3,418
Richardson Land II | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			0
Richardson Land II | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 0
Crown Pointe
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Feb. 14, 2017
Total Real Estate, at Cost			$ 95,526
Accumulated Depreciation and Amortization			(11,753)
Total Real Estate, Net			$ 83,773
Ownership %			100.00%
Crown Pointe | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 22,590
Crown Pointe | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			68,106
Crown Pointe | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 4,830
Marquette Plaza
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Mar. 01, 2018
Total Real Estate, at Cost			$ 95,631
Accumulated Depreciation and Amortization			(7,119)
Total Real Estate, Net			$ 88,512
Ownership %			100.00%
Marquette Plaza | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 10,387
Marquette Plaza | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			81,065
Marquette Plaza | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 4,179
City Tower
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Mar. 06, 2018
Total Real Estate, at Cost			$ 157,257
Accumulated Depreciation and Amortization			(12,823)
Total Real Estate, Net			$ 144,434
Ownership %			100.00%
City Tower | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 13,930
City Tower | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			135,390
City Tower | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 7,937
Eight & Nine Corporate Centre
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Jun. 08, 2018
Total Real Estate, at Cost			$ 79,568
Accumulated Depreciation and Amortization			(4,356)
Total Real Estate, Net			$ 75,212
Ownership %			100.00%
Eight & Nine Corporate Centre | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 17,401
Eight & Nine Corporate Centre | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			57,595
Eight & Nine Corporate Centre | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 4,572
Georgia 400 Center
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			May 23, 2019
Total Real Estate, at Cost			$ 91,534
Accumulated Depreciation and Amortization			(3,053)
Total Real Estate, Net			$ 88,481
Ownership %			100.00%
Georgia 400 Center | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 11,431
Georgia 400 Center | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			72,529
Georgia 400 Center | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			7,574
Total Single-Family Homes Portfolio
Real Estate Properties [Line Items]
Total Real Estate, at Cost			110,138
Accumulated Depreciation and Amortization			(773)
Total Real Estate, Net			109,365
Total Single-Family Homes Portfolio | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			17,128
Total Single-Family Homes Portfolio | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			91,533
Total Single-Family Homes Portfolio | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			1,477
Birmingham Homes
Real Estate Properties [Line Items]
Total Real Estate, at Cost			13,650
Accumulated Depreciation and Amortization			(90)
Total Real Estate, Net			$ 13,560
Ownership %			100.00%
Birmingham Homes | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 2,444
Birmingham Homes | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			11,044
Birmingham Homes | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			162
Houston Homes
Real Estate Properties [Line Items]
Total Real Estate, at Cost			29,195
Accumulated Depreciation and Amortization			(191)
Total Real Estate, Net			$ 29,004
Ownership %			100.00%
Houston Homes | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 6,154
Houston Homes | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			22,609
Houston Homes | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			432
Jacksonville Homes
Real Estate Properties [Line Items]
Total Real Estate, at Cost			27,397
Accumulated Depreciation and Amortization			(210)
Total Real Estate, Net			$ 27,187
Ownership %			100.00%
Jacksonville Homes | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 2,986
Jacksonville Homes | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			24,058
Jacksonville Homes | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			353
Memphis Homes
Real Estate Properties [Line Items]
Total Real Estate, at Cost			18,609
Accumulated Depreciation and Amortization			(131)
Total Real Estate, Net			$ 18,478
Ownership %			100.00%
Memphis Homes | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 2,679
Memphis Homes | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			15,664
Memphis Homes | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			266
Atlanta Homes
Real Estate Properties [Line Items]
Total Real Estate, at Cost			4,687
Accumulated Depreciation and Amortization			(38)
Total Real Estate, Net			$ 4,649
Ownership %			100.00%
Atlanta Homes | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 783
Atlanta Homes | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			3,839
Atlanta Homes | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			65
Oklahoma Homes
Real Estate Properties [Line Items]
Total Real Estate, at Cost			16,600
Accumulated Depreciation and Amortization			(113)
Total Real Estate, Net			$ 16,487
Ownership %			100.00%
Oklahoma Homes | Land
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 2,082
Oklahoma Homes | Buildings and improvements
Real Estate Properties [Line Items]
Total Real Estate, at Cost			14,319
Oklahoma Homes | Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total Real Estate, at Cost			$ 199