Leases - Major Tenants - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2017 Property Tenant Lease	Sep. 30, 2016
Leases [Line Items]
Number of significant tenants | Tenant	3
Subsidiaries of Global Partners LP (NYSE GLP) [Member]
Leases [Line Items]
Number of leased properties | Property	163
Lease revenue percentage	21.00%	21.00%
Number of leased properties guaranteed	3
Subsidiaries of Chestnut Petroleum Dist. Inc.[Member]
Leases [Line Items]
Number of leased properties | Property	76
Lease revenue percentage	16.00%	14.00%
Number of unitary leases	2
Number of leased properties guaranteed	57
Apro, LLC (d/b/a United Oil) [Member]
Leases [Line Items]
Number of leased properties | Property	77
Lease revenue percentage	15.00%	15.00%
Number Of Unitary Leases To Tenant	3