Related Party Transactions - Summary of Fees and Expenses Incurred (Detail) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Fees and expenses, Due to related parties	$ 1,861,062	$ 2,057,181	$ 2,742,581
Fees and expenses, Incurred	1,536,164	4,242,081
Fees and expenses, Paid	1,732,283	4,927,481
Asset Management Fees [Member]
Related Party Transaction [Line Items]
Fees and expenses, Due to related parties	137,070	123,179	152,072
Fees and expenses, Incurred	793,437	1,840,152
Fees and expenses, Paid	779,546	1,869,045
Property Management and Oversight Fees [Member]
Related Party Transaction [Line Items]
Fees and expenses, Due to related parties	25,117	20,269	8,647
Fees and expenses, Incurred	72,688	110,415
Fees and expenses, Paid	67,840	98,793
Operating Expenses [Member]
Related Party Transaction [Line Items]
Fees and expenses, Due to related parties	204,253	204,253	1,004,539
Fees and expenses, Incurred		204,253
Fees and expenses, Paid		1,004,539
Organization Expenses [Member]
Related Party Transaction [Line Items]
Fees and expenses, Due to related parties	44,774	71,162	10,860
Fees and expenses, Incurred	444	77,193
Fees and expenses, Paid	26,832	16,891
Offering Costs [Member]
Related Party Transaction [Line Items]
Fees and expenses, Due to related parties	581,856	718,499	732,579
Fees and expenses, Incurred	169,667	287,289
Fees and expenses, Paid	306,310	301,369
Selling Commissions and Dealer Manager Fees, Net [Member]
Related Party Transaction [Line Items]
Fees and expenses, Due to related parties			27,846
Fees and expenses, Incurred	400,293	1,345,353
Fees and expenses, Paid	400,293	1,373,199
Distribution Fees [Member]
Related Party Transaction [Line Items]
Fees and expenses, Due to related parties	867,992	919,819	$ 806,038
Fees and expenses, Incurred	99,635	377,426
Fees and expenses, Paid	$ 151,462	$ 263,645