Investments in Real Estate Subsidiaries - Schedule of Investments in SPEs Properties (Details)	Sep. 30, 2023 a
Special Purpose Entities Directly Owned Companies
Summary of Investment Holdings [Line Items]
Effective ownership (as a percent)	100.00%
White Rock Center | Special Purpose Entities Directly Owned Companies
Summary of Investment Holdings [Line Items]
Effective ownership (as a percent)	100.00%
5916 W Loop 289 | Special Purpose Entities Directly Owned Companies
Summary of Investment Holdings [Line Items]
Effective ownership (as a percent)	100.00%
Cityplace Tower | Special Purpose Entities Directly Owned Companies
Summary of Investment Holdings [Line Items]
Effective ownership (as a percent)	100.00%
NexPoint Dominion Land, LLC | Special Purpose Entities Directly Owned Companies
Summary of Investment Holdings [Line Items]
Effective ownership (as a percent)	100.00%
NexPoint Dominion Land, LLC | Undeveloped Land in Plano, Texas
Summary of Investment Holdings [Line Items]
Area of land (acre)	21.5