Mortgages and Other Notes Payable - Schedule of Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 169,205	$ 183,392
Mortgages and other notes payable | 770 South Post Oak
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 11,596	11,635
Effective Interest Rate	4.40%
Mortgages and other notes payable | Athens
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 1,155	1,155
Effective Interest Rate	4.00%
Mortgages and other notes payable | Chelsea
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 7,996	8,037
Effective Interest Rate	3.40%
Mortgages and other notes payable | EQK Portage - Land
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 3,350	3,350
Effective Interest Rate	10.00%
Mortgages and other notes payable | Forest Grove
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 7,220	7,263
Effective Interest Rate	3.75%
Mortgages and other notes payable | Landing Bayou
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 14,345	14,407
Effective Interest Rate	3.50%
Mortgages and other notes payable | Legacy at Pleasant Grove
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 13,275	13,352
Effective Interest Rate	3.60%
Mortgages and other notes payable | New Concept Energy
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 3,542	3,542
Effective Interest Rate	6.00%
Mortgages and other notes payable | Parc at Denham Springs Phase II
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 15,919	15,962
Effective Interest Rate	4.10%
Mortgages and other notes payable | RCM HC Enterprises
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 5,086	5,086
Effective Interest Rate	9.50%
Mortgages and other notes payable | Standford Center
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 38,844	38,979
Effective Interest Rate	6.00%
Mortgages and other notes payable | Sugar Mill Phase III
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 9,196	9,216
Effective Interest Rate	4.50%
Mortgages and other notes payable | Toulon
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 0	13,697
Effective Interest Rate	3.20%
Mortgages and other notes payable | Villas at Bon Secour
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 19,496	19,492
Effective Interest Rate	3.08%
Mortgages and other notes payable | Vista Ridge
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 9,792	9,830
Effective Interest Rate	4.00%
Mortgages and other notes payable | Windmill Farms
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 8,393	$ 8,389
Effective Interest Rate	5.00%