Preferred Equity in our Operating Partnership - Additional Information (Detail) - USD ($)		1 Months Ended	3 Months Ended	12 Months Ended
	Jun. 28, 2017	Oct. 31, 2018	Aug. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Sep. 28, 2017
Preferred Units [Line Items]
Distribution description				The holders of Preferred Units receive distributions at a rate of 9.0% per annum (the “Pay Rate”), payable monthly and calculated on an actual/360 day basis. Accumulated but unpaid distributions, if any, accrue at the Pay Rate. The preferred units of limited partnership interests in our Operating Partnership rank senior to all classes or series of partnership interests in our Operating Partnership and therefore, any cash we have to pay distributions otherwise may be used to pay distributions to the holder of such preferred units first.
Distribution rate				9.00%
Repayments of bridge loan				$ 12,304,891	$ 39,896,363
Second Amended and Restated Limited Partnership Agreement [Member]
Preferred Units [Line Items]
Preferred investor investment in operating partnership	$ 5,650,000
SAM Preferred Investor Limited Liability Company [Member]
Preferred Units [Line Items]
Preferred investor investment in operating partnership			$ 6,300,000
Preferred investor received			252,000
Additional preferred units			2,520			40,220
Percentage of first tranche of investment			1.00%
Acquisition and loan deposits related to the acquisition	$ 1,010,000
Preferred units outstanding value				$ 10,200,000
SAM Preferred Investor Limited Liability Company [Member] | Power 5 Conference Student Housing [Member]
Preferred Units [Line Items]
Preferred investor investment in operating partnership		$ 800,000
SAM Preferred Investor Limited Liability Company [Member] | Utah Bridge Loan [Member]
Preferred Units [Line Items]
Preferred investor investment in operating partnership		$ 3,000,000
Preferred investor received		150,550
Additional preferred units		1,505
Percentage of first tranche of investment		1.00%
Repayments of bridge loan			$ 2,900,000
SAM Preferred Investor Limited Liability Company [Member] | Portland Property [Member]
Preferred Units [Line Items]
Closing of property			$ 3,400,000
SAM Preferred Investor Limited Liability Company [Member] | Unit Purchase Agreement [Member]
Preferred Units [Line Items]
Liquidation preference per Preferred Unit	$ 25.00
Additional preferred units				402
Percentage of previously funded amounts issued				1.00%
SAM Preferred Investor Limited Liability Company [Member] | Unit Purchase Agreement [Member] | Maximum [Member]
Preferred Units [Line Items]
Redeemable preferred equity	$ 12,000,000
Preferred investor received	480,000
SAM Preferred Investor Limited Liability Company [Member] | Second Amended and Restated Limited Partnership Agreement [Member]
Preferred Units [Line Items]
Preferred investor received	226,000
Additional preferred units	2,260
Percentage of first tranche of investment	1.00%