Notes Payable - Summary of Mortgage Notes Payable (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term debt, gross	$ 306,793	$ 310,686
Less unamortized deferred loan costs	(3,754)	(4,779)
Total	$ 303,039	305,907
Richardson Heights
Debt Instrument [Line Items]
Rate	4.61%
Long-term debt, gross	$ 17,260	17,760
Cooper Street
Debt Instrument [Line Items]
Rate	4.61%
Long-term debt, gross	$ 7,435	7,632
Bent Tree Green
Debt Instrument [Line Items]
Rate	4.61%
Long-term debt, gross	$ 7,435	7,632
Mitchelldale
Debt Instrument [Line Items]
Rate	4.61%
Long-term debt, gross	$ 11,263	11,560
Promenade
Debt Instrument [Line Items]
Long-term debt, gross	$ 0	7,102
Hartman SPE LLC
Debt Instrument [Line Items]
Rate	3.60%
Long-term debt, gross	$ 259,000	259,000
Hartman XXI
Debt Instrument [Line Items]
Rate	10.00%
Long-term debt, gross	$ 4,400	$ 0

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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