Related Party Transactions - Summary of Related Party Costs - Related Party Transactions (Detail) - USD ($)		9 Months Ended	12 Months Ended
		Sep. 30, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Related party costs, Incurred		$ 6,784,170	$ 9,285,362
Related party costs, Paid		4,342,373	9,038,404
Related party costs, Payable		2,688,755	246,958
Operating Expenses Including Organizational Costs [Member]
Related Party Transaction [Line Items]
Related party costs, Incurred		498,830	394,654
Related party costs, Paid		550,938	271,229
Related party costs, Payable		71,317	123,425
Transfer Agent Expenses [Member]
Related Party Transaction [Line Items]
Related party costs, Incurred		85,194
Related party costs, Paid		58,000
Related party costs, Payable		27,194
Asset Management Fees [Member]
Related Party Transaction [Line Items]
Related party costs, Incurred	[1]	736,736	135,163
Related party costs, Paid	[1]	262,347	93,492
Related party costs, Payable	[1]	516,060	41,671
Property Management Oversight Fees [Member]
Related Party Transaction [Line Items]
Related party costs, Incurred		129,520
Related party costs, Paid		44,336
Related party costs, Payable		85,184
Acquisition Fees [Member]
Related Party Transaction [Line Items]
Related party costs, Incurred		148,736	2,310,020
Related party costs, Paid		148,736	2,310,020
Debt Issuance Costs Capitalized [Member]
Related Party Transaction [Line Items]
Related party costs, Incurred		357,025	499,382
Related party costs, Paid		390,907	465,500
Related party costs, Payable			33,882
Acquisition Expenses Capitalized [Member]
Related Party Transaction [Line Items]
Related party costs, Incurred		3,180,000
Related party costs, Paid		1,200,000
Related party costs, Payable		1,980,000
Additional Paid In Capital Selling Commissions [Member]
Related Party Transaction [Line Items]
Related party costs, Incurred		839,011	3,947,269
Related party costs, Paid		865,171	3,915,109
Related party costs, Payable		6,000	32,160
Additional Paid-in Capital Dealer Manager Fees [Member]
Related Party Transaction [Line Items]
Related party costs, Incurred		477,481	1,490,524
Related party costs, Paid		490,301	1,474,704
Related party costs, Payable		3,000	15,820
Additional Paid-in Capital Offering Costs [Member]
Related Party Transaction [Line Items]
Related party costs, Incurred		331,637	508,350
Related party costs, Paid		$ 331,637	$ 508,350

[1] For the year ended December 31, 2017 and the four months ended April 30, 2018, the Advisor permanently waived one half of the asset management fee totaling approximately $135,000 and $160,000, respectively. Such amounts were waived permanently and accordingly, will not be paid to the Advisor. Commensurate with our Public Offering being declared effective on May 1, 2018, the Advisor is no longer waiving the asset management fees.