Property Acquisitions - Additional Information (Detail)					3 Months Ended	12 Months Ended
	Feb. 26, 2020 USD ($) Property Option	Feb. 04, 2020 USD ($) Property Option	Nov. 22, 2019 USD ($) Property Option	Jun. 17, 2019 USD ($) Property Option	Mar. 31, 2020 USD ($) Property	Dec. 31, 2019 USD ($) Property	Mar. 31, 2019 Property
Business Acquisition [Line Items]
Number of car wash properties acquired during the period | Property					12
Aggregate purchase price of the car wash properties acquired during the period					$ 57,321,000
Number of gasoline stations and convenience stores acquired during the period | Property	10	10				27	0
Aggregate purchase price of the gasoline stations and convenience stores acquired during the period	$ 50,303,000	$ 50,303,000				$ 87,157,000
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	15 years		15 years
Number of unitary lease renewal options | Option	5	5		2
Unitary lease renewal term	5 years	5 years
Purchase price allocation, land acquired	$ 4,775,000	$ 4,775,000
Purchase price allocation, buildings and improvements acquired	41,093,000	41,093,000
Purchase price allocated to in-place leases	3,727,000	3,727,000
Purchase price allocated to above market leases	1,955,000	1,955,000
Purchase price allocated to below market leases	$ 1,247,000	$ 1,247,000
Gasoline Stations and Convenience Store Properties [Member]
Business Acquisition [Line Items]
Number of gasoline stations and convenience stores acquired during the period | Property					2	17
Aggregate purchase price of the gasoline stations and convenience stores acquired during the period					$ 7,018,000	$ 48,290,000
Other Acquisition [Member]
Business Acquisition [Line Items]
Purchase price allocation, land acquired					1,414,000	18,820,000
Purchase price allocation, buildings and improvements acquired					5,076,000	26,790,000
Purchase price allocated to in-place leases					$ 528,000	2,744,000
Purchase price allocated to above market leases						277,000
Purchase price allocated to below market leases						$ 341,000
1234M Division Street Inc [Member]
Business Acquisition [Line Items]
Number of gasoline stations and convenience stores acquired during the period | Property				6
Aggregate purchase price of the gasoline stations and convenience stores acquired during the period				$ 24,724,000
Unitary lease description					The unitary lease provides for an initial term of 15 years, with two ten-year renewal options. The unitary lease requires 1234 M 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 renewal term				10 years
Purchase price allocation, land acquired				$ 18,086,000
Purchase price allocation, buildings and improvements acquired				4,789,000
Purchase price allocated to in-place leases				$ 1,849,000
QNC OpCo Inc [Member]
Business Acquisition [Line Items]
Number of gasoline stations and convenience stores acquired during the period | Property			4
Aggregate purchase price of the gasoline stations and convenience stores acquired during the period			$ 14,144,000
Unitary lease description					The unitary lease requires QNC 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 allocation, land acquired			$ 2,663,000
Purchase price allocation, buildings and improvements acquired			10,469,000
Purchase price allocated to in-place leases			$ 1,012,000