Quarterly Financial Data (Unaudited) Quarterly Financial Data (Immaterial Restatement) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Supply and logistics		$ 974,696	$ 947,890	$ 893,263					$ 3,797,750	$ 2,825,768	$ 1,894,612
Revenues	1,054,072	1,041,837	1,013,431	960,717	806,881	830,200	762,790	689,798	4,070,057	3,089,669	2,101,324
Supply and logistics costs		911,399	883,176	835,869					3,707,411	2,766,808	1,858,862
Costs and Expenses		1,012,719	985,762	933,987					3,956,367	3,007,217	2,128,708
Operating income (loss)	30,173	29,118	27,669	26,730	15,057	28,632	25,931	12,832	113,690	82,452	(27,384)
As Reported [Member]
Supply and logistics		875,193	857,127	865,489
Revenues		942,334	922,668	932,943
Supply and logistics costs		811,896	792,413	808,095
Costs and Expenses		913,216	894,999	906,213
Operating income (loss)		$ 29,118	$ 27,669	$ 26,730