Summary of Related Party Costs (Detail) - USD ($)		9 Months Ended	12 Months Ended
		Sep. 30, 2016	Dec. 31, 2015
Related Party Transaction [Line Items]
Related party costs, Incurred		$ 38,050,884	$ 25,164,607
Related party costs, Paid		35,487,164	29,280,359
Related party costs, Payable		2,772,203	208,483
Operating expenses (including organizational costs)
Related Party Transaction [Line Items]
Related party costs, Incurred		532,516	1,200,003
Related party costs, Paid		289,790	1,988,533
Related party costs, Payable		290,697	47,971
Asset management fees
Related Party Transaction [Line Items]
Related party costs, Incurred		1,930,642	865,757
Related party costs, Paid		1,838,664	888,011
Related party costs, Payable		91,978	0
Property management fees
Related Party Transaction [Line Items]
Related party costs, Incurred	[1]	1,845,551	1,259,135
Related party costs, Paid	[1]	1,762,972	1,306,422
Related party costs, Payable	[1]	82,579	0
Acquisition expenses
Related Party Transaction [Line Items]
Related party costs, Incurred		9,007,362	2,776,679
Related party costs, Paid		9,007,362	3,479,712
Related party costs, Payable		0	0
Deferred financing costs
Related Party Transaction [Line Items]
Related party costs, Incurred		0	214,006
Related party costs, Paid		0	655,879
Related party costs, Payable		0	0
Other assets
Related Party Transaction [Line Items]
Related party costs, Incurred		0	77,556
Related party costs, Paid		0	539,048
Related party costs, Payable		0	0
Selling commissions
Related Party Transaction [Line Items]
Related party costs, Incurred	[2]	19,167,697	14,761,271
Related party costs, Paid	[2]	16,955,794	14,761,271
Related party costs, Payable	[2]	2,211,903	0
Dealer Manager fee
Related Party Transaction [Line Items]
Related party costs, Incurred		5,225,303	3,690,318
Related party costs, Paid		5,290,769	3,535,685
Related party costs, Payable		95,046	160,512
Offering costs
Related Party Transaction [Line Items]
Related party costs, Incurred		341,813	319,882
Related party costs, Paid		341,813	2,125,798
Related party costs, Payable		$ 0	$ 0

[1] During the year ended December 31, 2015, property management fees included approximately $0.3 million of fees paid to the sub-property manager of our properties. During the nine months ended September 30, 2016, property management fees included approximately $1.3 million of fees paid to the sub-property manager of our properties.

[2] The Company pays our Dealer Manager an ongoing stockholder servicing fee that is payable monthly and accrues daily in an amount equal to 1/365th of 1% of the purchase price per share of the Class T Shares sold in the Primary Offering. As of September 30, 2016, we had incurred approximately $2.5 million and paid approximately $0.3 million of such stockholder servicing fees.