Organization and Business (Details) ft² in Millions	Oct. 01, 2020 USD ($)	Sep. 30, 2020 property	Sep. 30, 2020	Sep. 30, 2020 ft²	Sep. 30, 2020 padSite	Sep. 30, 2020 landDevelopment	Sep. 30, 2019 property	Sep. 30, 2019 ft²	Sep. 30, 2019 padSite	Sep. 30, 2019 landDevelopment	Oct. 01, 2018 USD ($) property
Advisor
Schedule of Equity Method Investments [Line Items]
Ownership percentage acquired			70.00%
Subsequent Event
Schedule of Equity Method Investments [Line Items]
Value of share-based compensation | $	$ 100,000
Texas
Schedule of Equity Method Investments [Line Items]
Number of real estate properties					4	2			3	0
Number of commercial properties		44					43
Area of real estate property (in sq ft) | ft²				6.8				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		26					25
San Antonio, Texas
Schedule of Equity Method Investments [Line Items]
Number of real estate properties		3					3
Variable Interest Entity, Not Primary Beneficiary | 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