Related Parties (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Related party transactions entered into for the time periods presented
Sales and revenues	$ 864,216	$ 531,452	$ 474,724
Purchases of product	636,144	454,314	411,423
Lease income	6,128	5,431	5,442
Labor and benefits reimbursement	10,784	10,760	10,195
Other expenses	192
Accounts receivable at December 31	14,730	14,991	13,641
Accounts payable at December 31	$ 24,530	$ 13,930	$ 18,069