Related Party Transactions - Additional Information (Detail) - USD ($)					1 Months Ended	3 Months Ended		12 Months Ended
	Apr. 17, 2020	Jul. 10, 2019	May 01, 2018	Oct. 20, 2017	Oct. 31, 2018	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Sep. 06, 2018
Related Party Transaction [Line Items]
Dealer manager agreement termination notice period	60 days
Dealer manager agreement termination date	Jun. 16, 2020
Maximum period for reimbursement of offering cost						60 days
Reduction in due to affiliates						$ (618,224)	$ (495,291)
Acquisition fee as percentage of contract purchase price						2.00%
Monthly asset management fee						0.05417%
Monthly asset management fee one twelfth of less than one percentage of average invested assets						one twelfth of 0.65%
Gross proceeds from issuance of common stock							$ 3,313,677
Liability for future payment						$ 9,661,657		$ 9,043,433
Reno Student Housing, DST [Member]
Related Party Transaction [Line Items]
Proceeds from Private Offering				$ 1,030,000.00
Beneficial interest percentage				2.60%
Power 5 Conference Student Housing [Member]
Related Party Transaction [Line Items]
Beneficial interest percentage					1.40%	1.40%
Proceeds from issuance of preferred units in operating partnership					$ 800,000
Advisory Agreements [Member]
Related Party Transaction [Line Items]
Gross proceeds from offering, threshold percentage of expenses for reimbursement						15.00%
Acquisition fee as percentage of contract purchase price										1.75%
Monthly asset management fee			0.05208%
Monthly asset management fee one twelfth of less than one percentage of average invested assets						one twelfth of 0.625%
Increase in monthly asset management fee			0.66667%
Increase in monthly asset management fee one twelfth of less than one percentage of average invested assets						one twelfth of 0.8%
Operating expenses reimbursement percentage of average investment in assets						2.00%
Operating expenses reimbursement percentage of net income						25.00%
Operating expenses exceed limitation						12 months
Maximum days for disclosure fact						60 days
Advisory Agreement [Member]
Related Party Transaction [Line Items]
Acquisition fee as percentage of contract purchase price		1.00%
Percentage of cumulative non-compounded annual return on invested capital to shareholders distributions		6.00%
Additional Percentage Of Cumulative Non Compounded Annual Return On Invested Capital To Shareholders Distributions		13.00%
Additional Acquisition Fee As Percentage Of Contract Purchase Price		2.00%
Disposition fees percentage of sale price of property		1.00%
Percentage of competitive real estate commission		50.00%
Select Capital Corporation (Dealer Manager) [Member]
Related Party Transaction [Line Items]
Underwriting compensation						10.00%
Percentage of non-voting equity interest						15.00%
Percentage owned by affiliate in advisor						2.50%
SSSHT Property Management, LLC (Property Manager) [Member]
Related Party Transaction [Line Items]
Property Managers fee percentage description						We pay our Property Manager an oversight fee equal to 1% of the gross revenues attributable to such properties; provided, however, that our Property Manager will receive an oversight fee equal to 1.5% of the gross revenues attributable to any senior housing property other than such properties that are leased to third party tenants under triple-net or similar lease structures. In the event any of our properties are managed directly by our Property Manager, we will pay our Property Manager a property management fee that is approved by a majority of our board of directors, including a majority of our independent directors not otherwise interested in such transaction, as being fair and reasonable to us and on terms and conditions not less favorable to us than those available from unaffiliated third parties.
Percentage of oversight fee equal to gross revenues						1.00%
SSSHT Property Management, LLC (Property Manager) [Member] | Senior Housing Properties [Member]
Related Party Transaction [Line Items]
Percentage of oversight fee equal to gross revenues						1.50%
Advisor Funding Agreement [Member]
Related Party Transaction [Line Items]
Maximum period for reimbursement of offering cost		60 days				60 days
Maximum period for reimbursement of offering expenses		60 days				60 days
Primary Offering And Termination of Dealer Manager [Member]
Related Party Transaction [Line Items]
Reduction in due to affiliates								$ 600,000
Primary Offering Dealer Manager Agreement [Member] | Select Capital Corporation (Dealer Manager) [Member]
Related Party Transaction [Line Items]
Underwriting compensation						10.00%
Stockholder Servicing Fees and Dealer Manager Servicing Fees [Member]
Related Party Transaction [Line Items]
Liability for future payment						$ 0
Minimum [Member] | Advisor Funding Agreement [Member]
Related Party Transaction [Line Items]
Percentage of organization and offering expenses funded by our advisor		1.00%				1.00%
Minimum [Member] | Primary Offering And Termination of Dealer Manager [Member]
Related Party Transaction [Line Items]
Percentage of organization and offering expenses expected at termination of public offering						1.00%
Percentage of receivable from advisor for organization and offering expenses incurred								1.00%
Underwriting compensation						10.00%
Maximum [Member]
Related Party Transaction [Line Items]
Financing fee percentage			0.50%
Maximum [Member] | Advisor Funding Agreement [Member]
Related Party Transaction [Line Items]
Percentage of organization and offering expenses funded by our advisor		1.00%				1.00%
Class W Common Stock [Member]
Related Party Transaction [Line Items]
Reimbursement of offering cost rate						1.00%
Class W Common Stock [Member] | Advisory Agreements [Member]
Related Party Transaction [Line Items]
Reimbursement of offering cost rate						1.00%
Class Y and Z Common Stock [Member]
Related Party Transaction [Line Items]
Gross proceeds from issuance of common stock									$ 11,900,000
Sales commissions and dealer manager fees									800,000
Organization and offering expenses									$ 800,000
Class Y and Z Common Stock [Member] | Advisor Funding Agreement [Member]
Related Party Transaction [Line Items]
Reimbursement of offering cost rate						1.00%
Class Y and Z Common Stock [Member] | Minimum [Member]
Related Party Transaction [Line Items]
Percentage of organization and offering expenses funded by our advisor						1.00%
Class Y and Z Common Stock [Member] | Minimum [Member] | Primary Offering And Termination of Dealer Manager [Member]
Related Party Transaction [Line Items]
Percentage of organization and offering expenses expected at termination of public offering						1.00%		1.00%
Class Y Common Stock [Member] | Primary Offering [Member]
Related Party Transaction [Line Items]
Estimation of organization and offering expenses for sale of stock		1.00%
Gross proceeds from issuance of common stock		$ 250,000,000
Class Y Common Stock [Member] | Select Capital Corporation (Dealer Manager) [Member]
Related Party Transaction [Line Items]
Sale commission fees percentage of proceed from Primary Offering		3.00%				3.00%
Dealer manager fees percentage of proceed from sales in primary portion of offering		3.00%				3.00%
Class Z Common Stock [Member] | Primary Offering [Member]
Related Party Transaction [Line Items]
Estimation of organization and offering expenses for sale of stock		1.00%
Class A Common Stock [Member] | Select Capital Corporation (Dealer Manager) [Member]
Related Party Transaction [Line Items]
Sale commission fees percentage of proceed from Primary Offering						6.00%
Maximum dealer manager fee percentage of proceeds from sales in Primary Private Offering						3.00%
Class T Common Stock [Member] | Select Capital Corporation (Dealer Manager) [Member]
Related Party Transaction [Line Items]
Sale commission fees percentage of proceed from Primary Offering						3.00%
Maximum dealer manager fee percentage of proceeds from sales in Primary Private Offering						3.00%
Class T and Y Common Stock [Member] | Additional Paid In Capital Selling Commissions [Member] | Select Capital Corporation (Dealer Manager) [Member]
Related Party Transaction [Line Items]
Monthly stockholder servicing fee accrual description						accrued daily in an amount equal to 1/365th of 1% of the purchase price per share
Class W and Z Common Stock [Member] | Additional Paid In Capital Selling Commissions [Member] | Select Capital Corporation (Dealer Manager) [Member]
Related Party Transaction [Line Items]
Monthly stockholder servicing fee accrual description						accrued daily in an amount equal to 1/365th of 0.5% of the purchase price per share
Class W or Z Common Stock [Member] | Select Capital Corporation (Dealer Manager) [Member]
Related Party Transaction [Line Items]
Servicing fee percentage						9.00%