Summary of Significant Accounting Policies (Details)		3 Months Ended		9 Months Ended		12 Months Ended
	Oct. 01, 2018 extension	Sep. 30, 2020 USD ($) monthlyPayment	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) extension monthlyPayment	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2020
Property, Plant and Equipment [Line Items]
Impairment of real estate				$ 0		$ 0
Goodwill impairment loss		$ 0	$ 0	0	$ 0
Net income		$ (2,173,000)	$ (333,000)	$ 2,417,000	$ (904,000)
Number of lease payments remaining | monthlyPayment		60		60
Total payments under lease		$ 240,000		$ 240,000
Through September 30, 2020
Property, Plant and Equipment [Line Items]
Monthly payment due		3,500		3,500
October 1, 2020 through September 30, 2025
Property, Plant and Equipment [Line Items]
Monthly payment due		$ 4,000		$ 4,000
Notes Payable to Banks | Hartman SPE, LLC
Property, Plant and Equipment [Line Items]
Number of extensions | extension	3			3
Extension term	1 year			1 year
Debt yield, minimum				12.50%
Debt yield							13.25%
Building and Building Improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life				5 years
Building and Building Improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life				39 years