Organization and Business (Details) ft² in Millions	Mar. 31, 2020 ft² property	Dec. 31, 2019 ft²	Mar. 31, 2019 ft² property	Oct. 01, 2018 USD ($) property
Texas
Schedule of Equity Method Investments [Line Items]
Number of commercial properties	43		43
Number of real estate properties	3		3
Area of real estate property (in sq ft) | ft²	6.7	6.7	6.7
Richardson, Arlington And Dallas, Texas
Schedule of Equity Method Investments [Line Items]
Number of real estate properties	15		15
Houston, Texas
Schedule of Equity Method Investments [Line Items]
Number of real estate properties	25		25
San Antonio, Texas
Schedule of Equity Method Investments [Line Items]
Number of real estate properties	3		3
Hartman SPE, LLC
Schedule of Equity Method Investments [Line Items]
Number of real estate properties				39
Hartman SPE, LLC | Notes Payable to Banks
Schedule of Equity Method Investments [Line Items]
Debt instrument, face amount | $				$ 259,000,000