Mortgages and Other Notes Payable - Schedule of Debt (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Aug. 25, 2021	Jun. 04, 2021	Mar. 04, 2021	Dec. 31, 2020
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 176,750				$ 236,069
Mortgages and Other Notes Payable
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	176,750				236,069
Mortgages and Other Notes Payable | 600 Las Colinas
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 0				35,589
Interest Rate	5.30%
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	$ 11,635				11,871
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
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	$ 8,037				8,194
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
Interest Rate	10.00%
Mortgages and Other Notes Payable | HSW Partners
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 0				14,690
Interest Rate	9.50%
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	$ 7,263				7,333
Interest Rate	3.75%
Mortgages and Other Notes Payable | Forest Grove | Prime Rate
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Variable interest rate	0.50%
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	$ 14,407				14,643
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	$ 13,352				13,653
Interest Rate	3.60%
Mortgages and Other Notes Payable | McKinney 36 Land
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 0				820
Interest Rate	8.00%
Mortgages and Other Notes Payable | Overlook at Allensville Phase II
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 0				15,621
Interest Rate	3.80%
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	$ 15,962				16,128
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	$ 1,986		$ 1,986		0
Interest Rate	9.50%
Mortgages and Other Notes Payable | Stanford Center
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Mortgages and other notes payable	$ 38,979				39,093
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	$ 9,216				9,298
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	$ 13,697				13,975
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	$ 19,492	$ 20,015			10,280
Interest Rate	3.08%	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	$ 9,830				9,979
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	$ 8,389				$ 10,397
Interest Rate	5.00%			5.00%