Derivative Instruments And Hedging Activities Derivatives and Hedging Instruments Gains Losses due to Settlements Hedge Ineffectiveness (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Trading Activity, Gains and Losses, Net [Line Items]
Change in fair value, effective portion	$ 430	$ 4,580	$ (5,217)	$ 145,046
Gain reclassified to earnings due to settlements	(9,774)	(14,400)	(29,268)	(33,357)
Amortization of discontinued hedges reclassified to earnings	270	270	810	810
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	(9,074)	(9,550)	(33,675)	112,499
Gain (Loss) Recognized in Earnings due to Settlements	9,504	14,130	28,458	32,547
Gain (Loss) Attributable to Hedge Ineffectiveness Recognized in Earnings	638	(4,790)	4,649	(5,596)
Sales [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Gain (Loss) Recognized in Earnings due to Settlements	57,513	(6,202)	156,445	(80,475)
Gain (Loss) Attributable to Hedge Ineffectiveness Recognized in Earnings		1,498	(274)	1,498
Cost of Sales [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Gain (Loss) Recognized in Earnings due to Settlements	(44,023)	20,776	(115,756)	111,217
Gain (Loss) Attributable to Hedge Ineffectiveness Recognized in Earnings	638	(6,189)	4,376	(6,189)
Operating Expense [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Gain (Loss) Recognized in Earnings due to Settlements	$ (3,986)	(444)	(12,231)	1,805
Gain (Loss) Attributable to Hedge Ineffectiveness Recognized in Earnings		$ (99)	$ 547	$ (905)