Accounts Receivable (Schedule Of Accounts Receivable) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Accounts Receivable, Net [Abstract]
Trade customers	$ 388,949	$ 391,401
Affiliates	258	122
Allowance for doubtful accounts	(11,172)	(10,969)
Receivables from trade customers and affiliates, net	378,035	380,554
Federal and state taxes	4,011	16,113
Other	18,113	10,705
Accounts receivable, net	$ 400,159	$ 407,372