Organization - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Mar. 02, 2016
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Aggregate offering proceeds	$ 19,009,962	$ 16,448,354
Common stock, shares sold	4,900,000	2,200,000
Initial Public Offering
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Common stock, value authorized			$ 1,750,000,000
Aggregate offering proceeds	$ 51,200,000
Common stock, shares sold	4,900,000
Reinvestment Plan
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Common stock, value authorized			$ 250,000,000
Aggregate offering proceeds	$ 1,200,000
Common stock, shares sold	100,000