Lease Financing Obligations (Details) (USD $)			1 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Apr. 30, 2013 Subsequent event item	Mar. 31, 2013 Fuel stations
Future minimum lease payments under these financing obligations
Remaining in 2013				$ 5,006,000
2014				6,876,000
2015				6,992,000
2016				7,007,000
2017				6,979,000
Thereafter				89,113,000
Total future minimum lease payments				121,973,000
Less Interest component				46,364,000
Present value of minimum lease payments				75,609,000
Current portion	2,462,000	2,187,000		2,462,000
Long-term portion	73,147,000	73,793,000		73,147,000
Number of sites related to which a right of first offer with respect to the re-purchase was executed			4
Re-purchase price of sites			7,100,000
Remaining lease finance obligation balance			$ 5,100,000