Organization and Basis of Presentation - Additional Information (Detail) (USD $)	1 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013
Organization And Basis Of Presentation [Line Items]
Payment to affiliate for commission sites	$ 3,500,000	$ 3,508,000
Payments to affiliates for motor fuel inventory	1,700,000
Accounts Receivable [Member]
Organization And Basis Of Presentation [Line Items]
Reconciliation of accounts receivable and accounts payable		2,000,000
Accounts Payable [Member]
Organization And Basis Of Presentation [Line Items]
Reconciliation of accounts receivable and accounts payable		$ 2,000,000