Property Acquisitions - Additional Information (Detail)	1 Months Ended		3 Months Ended
	Mar. 31, 2021 USD ($) Property Option	Feb. 29, 2020 USD ($) Property Option	Mar. 31, 2021 USD ($) Property	Mar. 31, 2020 USD ($) Property
Business Acquisition [Line Items]
Number of real estate properties, fee simple | Property	6		6
Aggregate purchase price of properties acquired during the period			$ 21,852,000	$ 57,321,000
Properties Acquired in Separate Transactions [Member]
Business Acquisition [Line Items]
Aggregate purchase price of properties acquired during the period			$ 7,905,000
Number of car wash properties acquired during the period | Property	2		2
Purchase price allocated to land	$ 1,865,000		$ 1,865,000
Purchase price allocated to buildings and improvements	5,396,000		5,396,000
Purchase price allocated to in-place leases	644,000		$ 644,000
Properties Acquired on March 2021 [Member]
Business Acquisition [Line Items]
Aggregate purchase price of properties acquired during the period	$ 13,947,000
Number of car wash properties acquired during the period | Property	4		4
Unitary lease description	The unitary lease requires our tenant to pay a fixed annual rent plus all amounts pertaining to the properties, including environmental expenses, real estate taxes, assessments, license and permit fees, charges for public utilities and all other governmental charges. Rent is scheduled to increase annually during the initial and renewal terms of the lease.
Unitary lease initial term	15 years
Number of unitary lease renewal options | Option	5
Unitary lease renewal term	5 years
Purchase price allocated to land	$ 2,782,000		$ 2,782,000
Purchase price allocated to buildings and improvements	9,997,000		9,997,000
Purchase price allocated to in-place leases	$ 1,168,000		$ 1,168,000
Properties Acquired on February 2020 [Member]
Business Acquisition [Line Items]
Aggregate purchase price of properties acquired during the period		$ 50,303,000
Number of car wash properties acquired during the period | Property		10
Unitary lease description		The unitary lease requires our tenant to pay a fixed annual rent plus all amounts pertaining to the properties, including environmental expenses, real estate taxes, assessments, license and permit fees, charges for public utilities and all other governmental charges. Rent is scheduled to increase annually during the initial and renewal terms of the lease.
Unitary lease initial term		15 years
Number of unitary lease renewal options | Option		5
Unitary lease renewal term		5 years
Purchase price allocated to land		$ 4,775,000
Purchase price allocated to buildings and improvements		41,093,000
Purchase price allocated to in-place leases		3,727,000
Purchase price allocated to above market leases		1,955,000,000
Purchase price allocated to below market leases		$ 1,247,000,000
Properties Acquired in Separate Transactions [Member]
Business Acquisition [Line Items]
Aggregate purchase price of properties acquired during the period				$ 7,018,000
Number of car wash properties acquired during the period | Property				2
Purchase price allocated to land				$ 1,414,000
Purchase price allocated to buildings and improvements				5,076,000
Purchase price allocated to in-place leases				$ 528,000