Derivatives (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011 Natural Gas Derivative Instruments [Member] Fixed price swaps [Member] 2011 [Member]	Jun. 30, 2011 Natural Gas Derivative Instruments [Member] Puts [Member] 2011 [Member]	Jun. 30, 2011 Natural Gas Derivative Instruments [Member] PEPL puts [Member] 2011 [Member]		Jul. 15, 2011 Natural Gas Derivative Instruments [Member] 2011 [Member]	Jun. 30, 2011 Natural Gas Derivative Instruments [Member] 2011 [Member]	Jun. 30, 2011 Oil Derivative Instruments [Member] Fixed price swaps [Member] 2011 [Member]		Jun. 30, 2011 Oil Derivative Instruments [Member] Puts [Member] 2011 [Member]	Jun. 30, 2011 Oil Derivative Instruments [Member] Collars [Member] 2011 [Member]	Jul. 15, 2011 Oil Derivative Instruments [Member] 2011 [Member]	Jun. 30, 2011 Oil Derivative Instruments [Member] 2011 [Member]	Jun. 30, 2011 Natural Gas Basis Differential Positions [Member] PEPL basis swaps [Member] 2011 [Member]		Jun. 30, 2011 Oil Timing Differential Positions [Member] Trade month roll swaps [Member] 2011 [Member]		Jun. 30, 2011 Natural Gas Derivative Instruments [Member] Fixed price swaps [Member] 2012 [Member]	Jun. 30, 2011 Natural Gas Derivative Instruments [Member] Puts [Member] 2012 [Member]	Jun. 30, 2011 Natural Gas Derivative Instruments [Member] PEPL puts [Member] 2012 [Member]		Jul. 15, 2011 Natural Gas Derivative Instruments [Member] 2012 [Member]	Jun. 30, 2011 Natural Gas Derivative Instruments [Member] 2012 [Member]	Jun. 30, 2011 Oil Derivative Instruments [Member] Fixed price swaps [Member] 2012 [Member]		Jun. 30, 2011 Oil Derivative Instruments [Member] Puts [Member] 2012 [Member]	Jun. 30, 2011 Oil Derivative Instruments [Member] Collars [Member] 2012 [Member]	Jul. 15, 2011 Oil Derivative Instruments [Member] 2012 [Member]	Jun. 30, 2011 Oil Derivative Instruments [Member] 2012 [Member]	Jun. 30, 2011 Natural Gas Basis Differential Positions [Member] PEPL basis swaps [Member] 2012 [Member]		Jun. 30, 2011 Oil Timing Differential Positions [Member] Trade month roll swaps [Member] 2012 [Member]		Jun. 30, 2011 Natural Gas Derivative Instruments [Member] Fixed price swaps [Member] 2013 [Member]	Jun. 30, 2011 Natural Gas Derivative Instruments [Member] Puts [Member] 2013 [Member]	Jun. 30, 2011 Natural Gas Derivative Instruments [Member] PEPL puts [Member] 2013 [Member]		Jun. 30, 2011 Natural Gas Derivative Instruments [Member] 2013 [Member]	Jun. 30, 2011 Oil Derivative Instruments [Member] Fixed price swaps [Member] 2013 [Member]		Jun. 30, 2011 Oil Derivative Instruments [Member] Puts [Member] 2013 [Member]	Jun. 30, 2011 Oil Derivative Instruments [Member] Collars [Member] 2013 [Member]	Jun. 30, 2011 Oil Derivative Instruments [Member] 2013 [Member]	Jun. 30, 2011 Natural Gas Basis Differential Positions [Member] PEPL basis swaps [Member] 2013 [Member]		Jun. 30, 2011 Oil Timing Differential Positions [Member] Trade month roll swaps [Member] 2013 [Member]		Jun. 30, 2011 Natural Gas Derivative Instruments [Member] Fixed price swaps [Member] 2014 [Member]	Jun. 30, 2011 Natural Gas Derivative Instruments [Member] Puts [Member] 2014 [Member]	Jun. 30, 2011 Natural Gas Derivative Instruments [Member] PEPL puts [Member] 2014 [Member]		Jun. 30, 2011 Natural Gas Derivative Instruments [Member] 2014 [Member]	Jun. 30, 2011 Oil Derivative Instruments [Member] Fixed price swaps [Member] 2014 [Member]		Jun. 30, 2011 Oil Derivative Instruments [Member] Puts [Member] 2014 [Member]	Jun. 30, 2011 Oil Derivative Instruments [Member] Collars [Member] 2014 [Member]	Jun. 30, 2011 Oil Derivative Instruments [Member] 2014 [Member]	Jun. 30, 2011 Natural Gas Basis Differential Positions [Member] PEPL basis swaps [Member] 2014 [Member]		Jun. 30, 2011 Oil Timing Differential Positions [Member] Trade month roll swaps [Member] 2014 [Member]		Jun. 30, 2011 Natural Gas Derivative Instruments [Member] Fixed price swaps [Member] 2015 [Member]	Jun. 30, 2011 Natural Gas Derivative Instruments [Member] Puts [Member] 2015 [Member]	Jun. 30, 2011 Natural Gas Derivative Instruments [Member] PEPL puts [Member] 2015 [Member]		Jun. 30, 2011 Natural Gas Derivative Instruments [Member] 2015 [Member]	Jun. 30, 2011 Oil Derivative Instruments [Member] Fixed price swaps [Member] 2015 [Member]		Jun. 30, 2011 Oil Derivative Instruments [Member] Puts [Member] 2015 [Member]	Jun. 30, 2011 Oil Derivative Instruments [Member] Collars [Member] 2015 [Member]	Jun. 30, 2011 Oil Derivative Instruments [Member] 2015 [Member]	Jun. 30, 2011 Natural Gas Basis Differential Positions [Member] PEPL basis swaps [Member] 2015 [Member]		Jun. 30, 2011 Oil Timing Differential Positions [Member] Trade month roll swaps [Member] 2015 [Member]		Jun. 30, 2011 Natural Gas Derivative Instruments [Member] Fixed price swaps [Member] Year 2016 [Member]	Jun. 30, 2011 Natural Gas Derivative Instruments [Member] Puts [Member] Year 2016 [Member]	Jun. 30, 2011 Natural Gas Derivative Instruments [Member] PEPL puts [Member] Year 2016 [Member]		Jun. 30, 2011 Natural Gas Derivative Instruments [Member] Year 2016 [Member]	Jun. 30, 2011 Oil Derivative Instruments [Member] Fixed price swaps [Member] Year 2016 [Member]		Jun. 30, 2011 Oil Derivative Instruments [Member] Puts [Member] Year 2016 [Member]	Jun. 30, 2011 Oil Derivative Instruments [Member] Collars [Member] Year 2016 [Member]	Jun. 30, 2011 Oil Derivative Instruments [Member] Year 2016 [Member]	Jun. 30, 2011 Natural Gas Basis Differential Positions [Member] PEPL basis swaps [Member] Year 2016 [Member]		Jun. 30, 2011 Oil Timing Differential Positions [Member] Trade month roll swaps [Member] Year 2016 [Member]		Jun. 30, 2011 Oil Derivative Instruments [Member] Fixed price swaps [Member] Year 2017 [Member]	Jun. 30, 2011 Oil Derivative Instruments [Member] Fixed price swaps [Member] Year 2018 [Member]	Jun. 30, 2011 Commodity derivatives [Member]	Dec. 31, 2010 Commodity derivatives [Member]
Derivative [Line Items]
Annual Hedged Volume					15,950	9,699	6,630	[1]		32,279	2,932	[2]	1,176	138		4,246	17,770	[1]	1,380	[3]	49,410	25,364	0	[1]		74,774	7,741	[2]	2,196	0		9,937	37,735	[1]	5,490	[3]	57,067	25,295	0	[1]	82,362	8,413	[2]	2,190	0	10,603	38,854	[1]	5,475	[3]	66,156	23,178	0	[1]	89,334	9,034	[2]	0	0	9,034	42,194	[1]	5,475	[3]	75,190	23,178	0	[1]	98,368	9,216	[2]	0	0	9,216	42,194	[1]	0	[3]	18,300	0	0	[1]	18,300	549	[2]	0	0	549	0	[1]	0	[3]
Weighted Average Fixed Price					9.50				8.24	8.24	91.82	[2]			87.10	87.10					5.97				6.07	6.07	94.67	[2]			90.33	90.33					5.88				6.00	98.27	[2]			93.46					5.86				5.64	95.39	[2]			95.39					5.90				5.69	98.18	[2]			98.18					6.01				6.01	100.58	[2]			100.58
Weighted Average Short Put Price						5.97	8.50	[1]					75.00									6.25	0	[1]					75.00									6.25	0	[1]				75.00								5.00	0	[1]				0								5.00	0	[1]				0								0	0	[1]				0
Weighted Average Floor Price														90.00																0															0														0														0														0
Weighted Average Ceiling Price														112.25																0															0														0														0														0
Weighted Average PEPL basis swaps hedged differential																	(0.96)	[1]															(0.89)	[1]													(0.89)	[1]													(0.39)	[1]													(0.39)	[1]													0	[1]
Weighted Average Trade Month Roll Swaps Hedged Differential																			0.22	[3]															0.22	[3]													0.22	[3]													0.22	[3]													0	[3]													0	[3]
Amount of outstanding extendible fixed price oil swaps of daily production																																																																						1,000														14,750									14,750	13,750
Fixed price for the outstanding extendible oil swaps of daily production per Bbl	$ 100.00		$ 100.00
Volumes of natural gas production on settled derivatives	16,106		32,178
Average contract price per MMBtu on settled derivatives	8.24		8.25
Volumes of oil production on settled derivatives	1,839		3,671
Average contract price per barrel on settled derivatives	84.08		84.08
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value																																																																																															440,485,000	637,836,000
Derivative Liability, Fair Value																																																																																															470,024,000	398,902,000
Realized gains (losses): [Abstract]
Commodity derivatives [Member]	42,081,000	83,160,000	97,890,000	145,663,000
Interest rate swaps	0	0	0	(8,021,000)
Canceled derivatives	0	(74,275,000)	0	(74,275,000)
Total realized gains (losses)	42,081,000	8,885,000	97,890,000	63,367,000
Unrealized gains (losses): [Abstract]
Commodity derivatives	163,434,000	40,631,000	(261,851,000)	74,131,000
Interest rate swaps	0	41,030,000	0	25,889,000
Total unrealized gains (losses)	163,434,000	81,661,000	(261,851,000)	100,020,000
Total gains (losses): [Abstract]
Gains (losses) on oil and natural gas derivatives	205,515,000	123,791,000	(163,961,000)	219,794,000
Gains (losses) on interest rate swaps	0	(33,245,000)	0	(56,407,000)
Total gains (losses) on derivative instruments	$ 205,515,000	$ 90,546,000	$ (163,961,000)	$ 163,387,000

[1] Settle on the Panhandle Eastern Pipeline ("PEPL") spot price of natural gas to hedge basis differential associated with natural gas production in the Mid-Continent Deep and Mid-Continent Shallow regions.

[2] As presented in the table above, the Company has certain outstanding fixed price oil swaps on 1,000 Bbls of daily production for the year ending December 31, 2015, 14,750 Bbls of daily production for the years ending December 31, 2016, and December 31, 2017, and 13,750 Bbls of daily production for the year ending December 31, 2018, which may be extended annually at a price of $100.00 per Bbl if the counterparties determine that the strike prices are in-the-money on a designated date in each respective preceding year. The extension for each year is exercisable without respect to the other years.

[3] The Company hedges the timing risk associated with the sales price of oil in the Mid-Continent Deep, Mid-Continent Shallow and Permian Basin regions. In these regions, the Company generally sells oil for the delivery month at a sales price based on the average NYMEX price of light oil during that month, plus an adjustment calculated as a spread between the weighted average prices of the delivery month, the next month and the following month during the period when the delivery month is prompt (the "trade month roll"). The 2011 swaps hedge production volumes for October through December.