Real Estate - Additional Information (Details) ft² in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) ft² property	Dec. 31, 2018 USD ($)
Related Party Transaction [Line Items]
Depreciation expense | $	$ 16,917,000	$ 8,900,000
Amortization expense | $	$ 10,895,000	7,799,000
Area of property (in square feet) | ft²	6.7
Commercial properties | property	43
Number of real estate properties | property	39
Acquisition fees | $	$ 0	0
Asset management fees to advisor | $	$ 1,760,000	1,760,000
Economic development incentive agreement, annual grants, term	5 years
Economic development incentive agreement, annual grants, maximum amount | $	$ 1,500,000
Economic development incentive agreement, annual sales tax grants, term	10 years
Economic development incentive agreement, annual sales tax grants, application amount | $	$ 66,000	$ 82,000
Richardson, Arlington And Dallas, Texas
Related Party Transaction [Line Items]
Number of real estate properties | property	15
Houston, Texas
Related Party Transaction [Line Items]
Number of real estate properties | property	25
San Antonio, Texas
Related Party Transaction [Line Items]
Number of real estate properties | property	3
TEXAS
Related Party Transaction [Line Items]
Number of real estate properties | property	3