Equity - Additional Information (Details) - USD ($)				1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Dec. 01, 2018	Nov. 01, 2018	Oct. 01, 2018	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2016	Jun. 30, 2018	Mar. 31, 2018
Class Of Stock [Line Items]
Aggregate proceeds from public offering							$ 51,200,000	$ 23,300,000
Common stock, shares sold							4,900,000	2,200,000
Subscription proceeds pursuant to the Reinvestment Plan							$ 1,200,000	$ 221,000
Subscription proceeds pursuant to the Reinvestment Plan, shares							100,000	22,100
Cash distributions declared net of class-specific expenses							$ 1,400,000	$ 500,000
Cash distributions paid net of class-specific expenses							$ 1,400,000	$ 500,000
Stock dividends declared							35,000	35,000
Stock dividends issued (in shares)							14,000	14,000
Percentage of cash distributions considered as return on capital for income tax purposes							100.00%	100.00%
Amount of distributions to stockholders considered as return of capital by the company							$ 0	$ 0
Monthly cash distributions less class-specific expenses per share				$ 0.0480	$ 0.0480		$ 0.0480
Distributions to be paid and distributed date				Dec. 31, 2018
Dividends payable, date declared				2018-09	2018-09		2018-09
Redemption of common stock, per share				$ 10.05	$ 10.05		$ 10.05			$ 10.05	$ 10.05
Redemptions of common stock							$ 185,460
Class A Common Stock
Class Of Stock [Line Items]
Common stock, shares sold							93,663	378,053
Stock dividends issued (in shares)							8,021	5,454
Redemptions of common stock							$ 127,000	$ 0
Class T Common Stock
Class Of Stock [Line Items]
Redemptions of common stock							$ 59,000	$ 0
Subsequent Event
Class Of Stock [Line Items]
Cash distribution and stock dividend declared date		Nov. 01, 2018	Oct. 01, 2018
Scenario Forecast
Class Of Stock [Line Items]
Cash distribution and stock dividend declared date	Dec. 01, 2018
Private Placement
Class Of Stock [Line Items]
Aggregate proceeds from public offering									$ 251,250
Common stock, shares sold									25,125
Advisor
Class Of Stock [Line Items]
Stock dividends issued (in shares)					1,000	800	2,000	3,000
Advisor | Prior to Commencement of Offering
Class Of Stock [Line Items]
Aggregate proceeds from public offering							$ 200,000	$ 200,000
Common stock, shares sold							20,000	20,000