REAL ESTATE HELD FOR INVESTMENT - Schedule of Real Estate Investments (Details) - USD ($) $ in Thousands			3 Months Ended
	Jan. 08, 2019	Sep. 07, 2016	Mar. 31, 2020	Dec. 31, 2019
Real Estate Properties [Line Items]
Total real estate, cost			$ 829,588	$ 824,860
Accumulated depreciation and amortization			(74,128)	(65,381)
Total real estate, net			755,460	759,479
Preferred Class A | Subsidiary of Common Parent
Real Estate Properties [Line Items]
Non-voting preferred membership units sold		820
Interest rate on Class A non-voting preferred membership units		10.00%
Proceeds from sale of units		$ 800
Preferred Class A-2 | Subsidiary of Common Parent
Real Estate Properties [Line Items]
Non-voting preferred membership units sold	1,927
Interest rate on Class A non-voting preferred membership units	10.00%
Proceeds from sale of units	$ 1,900
Total Richardson Portfolio
Real Estate Properties [Line Items]
Total real estate, cost			46,275
Accumulated depreciation and amortization			(12,300)
Total real estate, net			$ 33,975
Palisades Central I
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Nov. 23, 2011
Total real estate, cost			$ 13,374
Accumulated depreciation and amortization			(3,787)
Total real estate, net			$ 9,587
Ownership %			90.00%
Palisades Central II
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Nov. 23, 2011
Total real estate, cost			$ 22,215
Accumulated depreciation and amortization			(5,894)
Total real estate, net			$ 16,321
Ownership %			90.00%
Greenway I
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Nov. 23, 2011
Total real estate, cost			$ 2,954
Accumulated depreciation and amortization			(1,118)
Total real estate, net			$ 1,836
Ownership %			90.00%
Greenway III
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Nov. 23, 2011
Total real estate, cost			$ 4,598
Accumulated depreciation and amortization			(1,501)
Total real estate, net			$ 3,097
Ownership %			90.00%
Undeveloped Land
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Nov. 23, 2011
Total real estate, cost			$ 3,134
Accumulated depreciation and amortization			0
Total real estate, net			$ 3,134
Ownership %			90.00%
Park Highlands
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Dec. 30, 2011
Total real estate, cost			$ 35,802
Accumulated depreciation and amortization			0
Total real estate, net			$ 35,802
Ownership %			100.00%
Park Centre
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Mar. 28, 2013
Total real estate, cost			$ 38,017
Accumulated depreciation and amortization			(7,091)
Total real estate, net			$ 30,926
Ownership %			100.00%
1180 Raymond
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Aug. 20, 2013
Total real estate, cost			$ 47,470
Accumulated depreciation and amortization			(8,216)
Total real estate, net			$ 39,254
Ownership %			100.00%
Park Highlands II
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Dec. 10, 2013
Total real estate, cost			$ 27,373
Accumulated depreciation and amortization			0
Total real estate, net			$ 27,373
Ownership %			100.00%
Richardson Land II
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Sep. 04, 2014
Total real estate, cost			$ 3,418
Accumulated depreciation and amortization			0
Total real estate, net			$ 3,418
Ownership %			90.00%
Crown Pointe
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Feb. 14, 2017
Total real estate, cost			$ 95,902
Accumulated depreciation and amortization			(12,558)
Total real estate, net			$ 83,344
Ownership %			100.00%
The Marq
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Mar. 01, 2018
Total real estate, cost			$ 95,664
Accumulated depreciation and amortization			(8,206)
Total real estate, net			$ 87,458
Ownership %			100.00%
City Tower
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Mar. 06, 2018
Total real estate, cost			$ 157,393
Accumulated depreciation and amortization			(14,570)
Total real estate, net			$ 142,823
Ownership %			100.00%
Eight & Nine Corporate Centre
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Jun. 08, 2018
Total real estate, cost			$ 79,840
Accumulated depreciation and amortization			(5,137)
Total real estate, net			$ 74,703
Ownership %			100.00%
Georgia 400 Center
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			May 23, 2019
Total real estate, cost			$ 91,929
Accumulated depreciation and amortization			(4,253)
Total real estate, net			$ 87,676
Ownership %			100.00%
Birmingham Homes
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Nov. 04, 2019
Total real estate, cost			$ 13,711
Accumulated depreciation and amortization			(206)
Total real estate, net			$ 13,505
Ownership %			100.00%
Houston Homes
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Nov. 04, 2019
Total real estate, cost			$ 29,300
Accumulated depreciation and amortization			(468)
Total real estate, net			$ 28,832
Ownership %			100.00%
Jacksonville Homes
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Nov. 04, 2019
Total real estate, cost			$ 27,493
Accumulated depreciation and amortization			(460)
Total real estate, net			$ 27,033
Ownership %			100.00%
Memphis Homes
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Nov. 04, 2019
Total real estate, cost			$ 18,660
Accumulated depreciation and amortization			(299)
Total real estate, net			$ 18,361
Ownership %			100.00%
Atlanta Homes
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Nov. 04, 2019
Total real estate, cost			$ 4,708
Accumulated depreciation and amortization			(84)
Total real estate, net			$ 4,624
Ownership %			100.00%
Oklahoma Homes
Real Estate Properties [Line Items]
Date Acquired or Foreclosed on			Nov. 04, 2019
Total real estate, cost			$ 16,633
Accumulated depreciation and amortization			(280)
Total real estate, net			$ 16,353
Ownership %			100.00%
Total Single-Family Homes Portfolio
Real Estate Properties [Line Items]
Total real estate, cost			$ 110,505
Accumulated depreciation and amortization			(1,797)
Total real estate, net			108,708
Land
Real Estate Properties [Line Items]
Total real estate, cost			177,247	175,317
Land | Total Richardson Portfolio
Real Estate Properties [Line Items]
Total real estate, cost			6,244
Land | Palisades Central I
Real Estate Properties [Line Items]
Total real estate, cost			1,037
Land | Palisades Central II
Real Estate Properties [Line Items]
Total real estate, cost			810
Land | Greenway I
Real Estate Properties [Line Items]
Total real estate, cost			561
Land | Greenway III
Real Estate Properties [Line Items]
Total real estate, cost			702
Land | Undeveloped Land
Real Estate Properties [Line Items]
Total real estate, cost			3,134
Land | Park Highlands
Real Estate Properties [Line Items]
Total real estate, cost			35,802
Land | Park Centre
Real Estate Properties [Line Items]
Total real estate, cost			3,251
Land | 1180 Raymond
Real Estate Properties [Line Items]
Total real estate, cost			8,292
Land | Park Highlands II
Real Estate Properties [Line Items]
Total real estate, cost			27,373
Land | Richardson Land II
Real Estate Properties [Line Items]
Total real estate, cost			3,418
Land | Crown Pointe
Real Estate Properties [Line Items]
Total real estate, cost			22,590
Land | The Marq
Real Estate Properties [Line Items]
Total real estate, cost			10,387
Land | City Tower
Real Estate Properties [Line Items]
Total real estate, cost			13,930
Land | Eight & Nine Corporate Centre
Real Estate Properties [Line Items]
Total real estate, cost			17,401
Land | Georgia 400 Center
Real Estate Properties [Line Items]
Total real estate, cost			11,431
Land | Birmingham Homes
Real Estate Properties [Line Items]
Total real estate, cost			2,444
Land | Houston Homes
Real Estate Properties [Line Items]
Total real estate, cost			6,154
Land | Jacksonville Homes
Real Estate Properties [Line Items]
Total real estate, cost			2,986
Land | Memphis Homes
Real Estate Properties [Line Items]
Total real estate, cost			2,679
Land | Atlanta Homes
Real Estate Properties [Line Items]
Total real estate, cost			783
Land | Oklahoma Homes
Real Estate Properties [Line Items]
Total real estate, cost			2,082
Land | Total Single-Family Homes Portfolio
Real Estate Properties [Line Items]
Total real estate, cost			17,128
Buildings and improvements
Real Estate Properties [Line Items]
Total real estate, cost			622,162	618,974
Buildings and improvements | Total Richardson Portfolio
Real Estate Properties [Line Items]
Total real estate, cost			40,031
Buildings and improvements | Palisades Central I
Real Estate Properties [Line Items]
Total real estate, cost			12,337
Buildings and improvements | Palisades Central II
Real Estate Properties [Line Items]
Total real estate, cost			21,405
Buildings and improvements | Greenway I
Real Estate Properties [Line Items]
Total real estate, cost			2,393
Buildings and improvements | Greenway III
Real Estate Properties [Line Items]
Total real estate, cost			3,896
Buildings and improvements | Undeveloped Land
Real Estate Properties [Line Items]
Total real estate, cost			0
Buildings and improvements | Park Highlands
Real Estate Properties [Line Items]
Total real estate, cost			0
Buildings and improvements | Park Centre
Real Estate Properties [Line Items]
Total real estate, cost			34,766
Buildings and improvements | 1180 Raymond
Real Estate Properties [Line Items]
Total real estate, cost			39,178
Buildings and improvements | Park Highlands II
Real Estate Properties [Line Items]
Total real estate, cost			0
Buildings and improvements | Richardson Land II
Real Estate Properties [Line Items]
Total real estate, cost			0
Buildings and improvements | Crown Pointe
Real Estate Properties [Line Items]
Total real estate, cost			68,872
Buildings and improvements | The Marq
Real Estate Properties [Line Items]
Total real estate, cost			81,098
Buildings and improvements | City Tower
Real Estate Properties [Line Items]
Total real estate, cost			135,526
Buildings and improvements | Eight & Nine Corporate Centre
Real Estate Properties [Line Items]
Total real estate, cost			57,867
Buildings and improvements | Georgia 400 Center
Real Estate Properties [Line Items]
Total real estate, cost			72,924
Buildings and improvements | Birmingham Homes
Real Estate Properties [Line Items]
Total real estate, cost			11,105
Buildings and improvements | Houston Homes
Real Estate Properties [Line Items]
Total real estate, cost			22,714
Buildings and improvements | Jacksonville Homes
Real Estate Properties [Line Items]
Total real estate, cost			24,154
Buildings and improvements | Memphis Homes
Real Estate Properties [Line Items]
Total real estate, cost			15,715
Buildings and improvements | Atlanta Homes
Real Estate Properties [Line Items]
Total real estate, cost			3,860
Buildings and improvements | Oklahoma Homes
Real Estate Properties [Line Items]
Total real estate, cost			14,352
Buildings and improvements | Total Single-Family Homes Portfolio
Real Estate Properties [Line Items]
Total real estate, cost			91,900
Tenant origination and absorption costs
Real Estate Properties [Line Items]
Total real estate, cost			30,179	$ 30,569
Tenant origination and absorption costs | Total Richardson Portfolio
Real Estate Properties [Line Items]
Total real estate, cost			0
Tenant origination and absorption costs | Palisades Central I
Real Estate Properties [Line Items]
Total real estate, cost			0
Tenant origination and absorption costs | Palisades Central II
Real Estate Properties [Line Items]
Total real estate, cost			0
Tenant origination and absorption costs | Greenway I
Real Estate Properties [Line Items]
Total real estate, cost			0
Tenant origination and absorption costs | Greenway III
Real Estate Properties [Line Items]
Total real estate, cost			0
Tenant origination and absorption costs | Undeveloped Land
Real Estate Properties [Line Items]
Total real estate, cost			0
Tenant origination and absorption costs | Park Highlands
Real Estate Properties [Line Items]
Total real estate, cost			0
Tenant origination and absorption costs | Park Centre
Real Estate Properties [Line Items]
Total real estate, cost			0
Tenant origination and absorption costs | 1180 Raymond
Real Estate Properties [Line Items]
Total real estate, cost			0
Tenant origination and absorption costs | Park Highlands II
Real Estate Properties [Line Items]
Total real estate, cost			0
Tenant origination and absorption costs | Richardson Land II
Real Estate Properties [Line Items]
Total real estate, cost			0
Tenant origination and absorption costs | Crown Pointe
Real Estate Properties [Line Items]
Total real estate, cost			4,440
Tenant origination and absorption costs | The Marq
Real Estate Properties [Line Items]
Total real estate, cost			4,179
Tenant origination and absorption costs | City Tower
Real Estate Properties [Line Items]
Total real estate, cost			7,937
Tenant origination and absorption costs | Eight & Nine Corporate Centre
Real Estate Properties [Line Items]
Total real estate, cost			4,572
Tenant origination and absorption costs | Georgia 400 Center
Real Estate Properties [Line Items]
Total real estate, cost			7,574
Tenant origination and absorption costs | Birmingham Homes
Real Estate Properties [Line Items]
Total real estate, cost			162
Tenant origination and absorption costs | Houston Homes
Real Estate Properties [Line Items]
Total real estate, cost			432
Tenant origination and absorption costs | Jacksonville Homes
Real Estate Properties [Line Items]
Total real estate, cost			353
Tenant origination and absorption costs | Memphis Homes
Real Estate Properties [Line Items]
Total real estate, cost			266
Tenant origination and absorption costs | Atlanta Homes
Real Estate Properties [Line Items]
Total real estate, cost			65
Tenant origination and absorption costs | Oklahoma Homes
Real Estate Properties [Line Items]
Total real estate, cost			199
Tenant origination and absorption costs | Total Single-Family Homes Portfolio
Real Estate Properties [Line Items]
Total real estate, cost			$ 1,477