Risk Concentrations Rick Concentrations (Schedule of Foreign Revenues) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
foreign revenue [Line Items]
Sales to customers in foreign countries	$ 1,200,000	$ 920,000	$ 471,500
Europe [Member]
foreign revenue [Line Items]
Sales to customers in foreign countries	674,754
South America [Member]
foreign revenue [Line Items]
Sales to customers in foreign countries	57,184
North America [Member]
foreign revenue [Line Items]
Sales to customers in foreign countries	72,542
Asia [Member]
foreign revenue [Line Items]
Sales to customers in foreign countries	203,193
Brokered Sales [Member]
foreign revenue [Line Items]
Sales to customers in foreign countries	145,438
Total [Member]
foreign revenue [Line Items]
Sales to customers in foreign countries	$ 1,153,111