Derivatives Derivates Impact on Income (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax [Roll Forward]
Price Risk Cash Flow Hedge Unrealized Gain (Loss) to be Reclassified During Next 12 Months	$ 30,333
Commodity Contract [Member] | Cash Flow Hedging [Member]
Accumulated Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax [Roll Forward]
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion	(79,899,000)	(189,259,000)	(95,007,000)
Commodity Contract [Member] | Sales [Member] | Cash Flow Hedging [Member]
Accumulated Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax [Roll Forward]
Derivative, Net Hedge Ineffectiveness Gain (Loss)	(4,645,000)	579,000	1,034,000
Accumulated Other Comprehensive Income (Loss) | Commodity Contract [Member] | Cash Flow Hedging [Member]
Accumulated Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax [Roll Forward]
Derivative Component Of Accumulated Other Comprehensive Income (Loss), Beginning of Period	76,761,000	151,780,000	46,087,000
Derivative Instruments, Gain Recognized in Other Comprehensive Income (Loss), Effective Portion	45,631,000	114,240,000	200,700,000
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion	79,899,000	189,259,000	95,007,000
Derivative Component Of Accumulated Other Comprehensive Income (Loss), End of Period	$ 42,493,000	$ 76,761,000	$ 151,780,000