Derivative Instruments And Hedging Activities Location of Gain Loss in Income Statement (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Price Risk Derivatives, Net	$ (29,672)	$ 20,473	$ 458	$ 56,184
Cost of Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Price Risk Derivatives, Net	(29,515)	19,869	5,916	55,738
Operating Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Price Risk Derivatives, Net	$ (157)	$ 604	$ (5,458)	$ 446