Property Acquisitions - 2014 Activity - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014 Property	Dec. 31, 2013 Property	May 09, 2013
Business Acquisition [Line Items]
Number of gasoline stations and convenience stores acquired during the period	10	3
Aggregate purchase price of the gasoline stations and convenience stores acquired during the period	$ 17,598	$ 750
Land Building And Equipment [Member] | Gasoline Stations and Convenience Store Properties [Member]
Business Acquisition [Line Items]
Purchase price allocation, assets acquired	16,576		62,365
Purchase price allocated to in-place lease and other intangible assets	1,022		3,868
Transaction cost related to acquisition	$ 104		$ 480