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, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Trading Activity, Gains and Losses, Net [Line Items]
Change in fair value	$ (2,095)	$ (1,511)	$ 2,620	$ (18,570)
Sales and other revenues	3,719,247	2,847,270	10,258,594	7,580,632
(Gain) loss reclassified to earnings due to settlements	5,179	4,046	5,228	37,012
Amortization of discontinued hedges reclassified to earnings	270	270	810	810
Operating expenses	321,668	256,232	944,437	760,151
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	3,354	2,805	8,658	19,252
Gain (Loss) Recognized in Earnings due to Settlements	(5,449)	(4,316)	(6,038)	(37,822)
Gain (Loss) Attributable to Hedge Ineffectiveness Recognized in Earnings	18	0	0	0
Operating Expense [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Gain (Loss) Attributable to Hedge Ineffectiveness Recognized in Earnings	18	0	0	0
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Commodity Contract [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Sales and other revenues	(488)	228	7,937	(20,425)
Cost of Goods Sold			(299)	0
Operating expenses	$ (4,961)	$ (4,544)	$ (13,676)	$ (17,397)