Segment and Geographic Information - Narrative (Details)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Segment Reporting Information [Line Items]
Number of geographical areas	2
Number of distribution centers	28
Number of distribution facilities operated as a third party logistics provider	2
Number of reportable segments	1
United States
Segment Reporting Information [Line Items]
Number of distribution centers	24
Number of consolidating warehouses	3
Canada
Segment Reporting Information [Line Items]
Number of distribution centers	4
Customer Concentration Risk [Member] | Couche-Tard [Member]
Segment Reporting Information [Line Items]
Major customer percentage of net sales	13.40%	13.50%