Derivative Financial Instruments Gains and Losses (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2013 Crude oil	Dec. 31, 2012 Crude oil	Dec. 31, 2011 Crude oil	Dec. 31, 2013 Natural Gas [Member]	Dec. 31, 2012 Natural Gas [Member]	Dec. 31, 2011 Natural Gas [Member]	Dec. 31, 2013 Natural Gas Liquids [Member]	Dec. 31, 2012 Natural Gas Liquids [Member]	Dec. 31, 2011 Natural Gas Liquids [Member]	Dec. 31, 2013 Convertible Debt [Member]	Dec. 31, 2012 Convertible Debt [Member]	Dec. 31, 2010 Convertible Debt [Member]
Derivative, (Gain) Loss on Derivative, Net [Abstract]
Derivative cash settlement (gain) loss:	$ (22,062)	[1]	$ (44,264)	[1]	$ 25,671	[1]	$ 15,161	$ 11,893	$ 22,633	$ (30,338)	$ (47,270)	$ (10,711)	$ (6,885)	$ (8,887)	$ 13,749
Derivative (gain) loss	(3,080)		(55,630)		(37,086)		(496)	(31,981)	(3,391)	16,285	31,777	(64,310)	3,193	(11,162)	4,944
Total derivative gain (2)	(3,080)	[2]	(55,630)	[2]	(37,086)	[2]
Amount reclassified from AOCIL	1,115		(2,264)		12,997
Gain (Loss) on Hedging Activity	$ (1,777)		$ 3,866		$ (20,707)
Debt Instrument, Interest Rate, Stated Percentage																3.50%	3.50%	3.50%

[1] Total derivative cash settlement gain (loss) is reported in the derivative cash settlement gain (loss) line item on the consolidated statements of cash flows within net cash provided by operating activities.

[2] Total derivative gain is reported in the derivative gain line item on the consolidated statements of cash flows within net cash provided by operating activities.