Earnings Per Share (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net loss	$ (2,601,903)	$ (1,388,450)	$ (5,387,310)	$ (2,214,605)
Undistributed net loss attributable to common stockholders	(3,954,981)	(2,145,570)	(7,997,432)	(3,559,537)
Common stock cash distributions declared	1,353,000	757,120	2,610,043	1,344,932
Class A Common Stock
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Undistributed net loss attributable to common stockholders	(222,354)	(236,156)	(475,477)	(437,649)
Common stock cash distributions declared	84,122	81,956	169,363	165,068
Net loss attributable to common stockholders	$ (138,232)	$ (154,200)	$ (306,114)	$ (272,581)
Net loss per common share, basic and diluted (in dollars per share)	$ (0.22)	$ (0.25)	$ (0.48)	$ (0.44)
Weighted-average shares outstanding, basic and diluted (in shares)	635,764	626,103	635,630	624,518
Class T Common Stock
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Undistributed net loss attributable to common stockholders	$ (391,026)	$ (411,109)	$ (834,933)	$ (761,725)
Common stock cash distributions declared	121,545	119,360	244,076	235,694
Net loss attributable to common stockholders	$ (269,481)	$ (291,749)	$ (590,857)	$ (526,031)
Net loss per common share, basic and diluted (in dollars per share)	$ (0.24)	$ (0.27)	$ (0.53)	$ (0.48)
Weighted-average shares outstanding, basic and diluted (in shares)	1,118,038	1,089,943	1,116,159	1,086,970
Class R Common Stock
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Undistributed net loss attributable to common stockholders	$ (3,136,689)	$ (1,451,507)	$ (6,325,262)	$ (2,295,752)
Common stock cash distributions declared	1,047,968	530,248	2,034,919	908,929
Net loss attributable to common stockholders	$ (2,088,721)	$ (921,259)	$ (4,290,343)	$ (1,386,823)
Net loss per common share, basic and diluted (in dollars per share)	$ (0.23)	$ (0.24)	$ (0.51)	$ (0.42)
Weighted-average shares outstanding, basic and diluted (in shares)	8,968,558	3,848,272	8,455,769	3,280,470
Class I Common Stock
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Undistributed net loss attributable to common stockholders	$ (204,912)	$ (46,798)	$ (361,760)	$ (64,411)
Common stock cash distributions declared	99,443	25,556	161,764	35,241
Net loss attributable to common stockholders	$ (105,469)	$ (21,242)	$ (199,996)	$ (29,170)
Net loss per common share, basic and diluted (in dollars per share)	$ (0.18)	$ (0.16)	$ (0.41)	$ (0.32)
Weighted-average shares outstanding, basic and diluted (in shares)	585,893	133,309	483,610	91,914