Summary of Significant Accounting Policies - Additional Information (Detail)		3 Months Ended		6 Months Ended		12 Months Ended
	Feb. 28, 2018 USD ($)	Jun. 30, 2021 USD ($) Lease	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) Segment Lease shares	Jun. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Summary of Significant Accounting Policies [Line Items]
Redemptions of shares | shares				0
Net impact to rental revenues due to the amortization of above market and below market leases				$ 100,000	$ 300,000
Amortization to below market leases		$ 2,886,000		2,886,000		$ 3,247,000
Income (loss) from investment		30,000	$ 33,000	61,000	56,000
Assets		506,571,000		506,571,000		512,093,000
Liabilities		425,672,000		425,672,000		427,796,000
Revenues		15,571,000	14,398,000	31,139,000	28,715,000
Expenses		9,717,000	$ 8,756,000	18,460,000	16,782,000
Impairment related to long-lived assets				$ 0		0
Number of reportable segments | Segment				1
Operating lease, right-of-use asset		$ 0		$ 0		$ 0
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]		us-gaap:OtherAssetsMember		us-gaap:OtherAssetsMember		us-gaap:OtherAssetsMember
Operating lease, right-of-use liability		$ 0		$ 0		$ 0
Operating Lease Liability Statement Of Financial Position Extensible List		us-gaap:OtherLiabilitiesMember		us-gaap:OtherLiabilitiesMember		us-gaap:OtherLiabilitiesMember
Income Tax Holiday, Description				The Company is organized and conducts its operations to qualify as a REIT for federal income tax purposes. Accordingly, the Company is generally not subject to federal income taxation on the portion of its distributable income that qualifies as REIT taxable income, to the extent that it distributes at least 90% of its REIT taxable income to its stockholders and complies with certain other requirements as defined in the Code.
Uncertain tax positions		$ 0		$ 0		$ 0
Standard maximum deposit insurance amount		$ 250,000		$ 250,000
Customer Concentration Risk [Member] | Sales Revenue Net [Member]
Summary of Significant Accounting Policies [Line Items]
Number of operating leases | Lease		5		5
Rental income				$ 4,800,000
Percentage of rental income				15.00%
Accounting Standards Update 2016-02 [Member]
Summary of Significant Accounting Policies [Line Items]
Monthly base rent		$ 24,000		$ 24,000
Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
Proportion Of Taxable Income Distributed to stockholders				90.00%		90.00%
Minimum [Member] | Properties and Property Improvements [Member]
Summary of Significant Accounting Policies [Line Items]
Estimated useful life				5 years
Minimum [Member] | Furniture, Fixtures and Equipment [Member]
Summary of Significant Accounting Policies [Line Items]
Estimated useful life				5 years
Maximum [Member] | Properties and Property Improvements [Member]
Summary of Significant Accounting Policies [Line Items]
Estimated useful life				40 years
Maximum [Member] | Furniture, Fixtures and Equipment [Member]
Summary of Significant Accounting Policies [Line Items]
Estimated useful life				10 years
Two CPS Developers LLC [Member]
Summary of Significant Accounting Policies [Line Items]
Percentage of interest purchased	50.00%
Business combination, consideration transferred	$ 5,250,000
Income (loss) from investment				$ 100,000	100,000
Above Market Lease [Member]
Summary of Significant Accounting Policies [Line Items]
Acquired lease intangible assets, net		400,000		400,000		$ 600,000
In-place Lease [Member]
Summary of Significant Accounting Policies [Line Items]
Acquired lease intangible assets, net		6,504,000		6,504,000		7,300,000
Buildings and Improvements [Member]
Summary of Significant Accounting Policies [Line Items]
Real estate under development		0		0		0
Investments in Unconsolidated Affiliates [Member]
Summary of Significant Accounting Policies [Line Items]
Assets		17,600,000		17,600,000		17,900,000
Liabilities		$ 10,000,000.0		10,000,000.0		$ 10,000,000.0
Revenues				800,000	800,000
Expenses				$ 700,000	$ 700,000