Leases - Getty Petroleum Marketing Inc. - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2021 USD ($) Property Portfolio
Leases [Line Items]
Number of leased properties subject to long-term triple-net leases | Property	317
Number of long-term triple-net leases during the period | Portfolio	14
Number of leased properties as single unit triple net leases | Portfolio	26
Maximum lease commitment for capital expenditure	$ 6,772,000
Unitary triple-net lease agreements initial terms	15 years
USTs [Member]
Leases [Line Items]
Asset retirement obligations removed from balance sheet	$ 13,813,000
Net asset retirement costs related to USTs removed from balance sheet	10,808,000
Deferred rental revenue	1,264,000
Deferred rental revenue accumulated amortization	$ 1,741,000
Maximum [Member]
Leases [Line Items]
Unitary triple-net lease agreements successive terms	20 years
Getty Petroleum Marketing Inc [Member]
Leases [Line Items]
Number of properties previously leased | Property	350