Derivative Commodity Instruments Derivative Commodity instruments not designated as hedging instruments on the Income Statement (Details) (Gain (loss) on derivative instruments, net, USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Gain (loss) on derivative instruments, net
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Open non-cash mark-to-market gains (losses) on derivative instruments	$ 141,743	$ (92,313)	$ (6,283)	$ (70,735)