Derivatives and Risk Management (Tables)

12 Months Ended

Dec. 31, 2011

Derivatives And Risk Management [Abstract]

Balance Sheet Classification of Derivative Financial Instruments

	Derivative Assets
	December 31, 2011		December 31, 2010
	Balance Sheet Classification	Fair Value	Balance Sheet Classification	Fair Value
	(in thousands)
Derivatives designated as hedging instruments:
Fixed and floating price swaps	Hedging asset	$        333,479	Hedging asset	$          81,797
Costless-collars	Hedging asset	179,080	Hedging asset	48,582
Fixed and floating price swaps	Other assets	201,081	Other assets	5,086
Costless-collars	Other assets	0	Other assets	72,827
Total derivatives designated as hedging instruments		$        713,640		$        208,292
Derivatives not designated as hedging instruments:
Basis swaps	Hedging asset	$             1,906	Hedging asset	$                 33
Basis swaps	Other assets	1,797	Other assets	0
Total derivatives not designated as hedging instruments		$             3,703		$                 33
Total derivative assets		$        717,343		$        208,325
	Derivative Liabilities
	December 31, 2011		December 31, 2010
	Balance Sheet Classification	Fair Value	Balance Sheet Classification	Fair Value
	(in thousands)
Derivatives designated as hedging instruments:
Fixed and floating price swaps	Hedging liability	$          11,849	Hedging liability	$            1,774
Costless-collars	Hedging liability	209	Hedging liability	3,903
Fixed and floating price swaps	Long-term hedging liability	0	Long-term hedging liability	22,334
Costless-collars	Long-term hedging liability	0	Long-term hedging liability	17,854
Total derivatives designated as hedging instruments		$          12,058		$          45,865
Derivatives not designated as hedging instruments:
Basis swaps	Hedging liability	$               400	Hedging liability	$            2,008
Basis swaps	Long-term hedging liability	55	Long-term hedging liability	0
Total derivatives not designated as hedging instruments		$               455		$            2,008
Total derivative liabilities		$          12,513		$          47,873

Cash Flow Hedges, Volumes of Natural Gas Production (in Bcf)

Year:	Fixed price swaps	Costless-collars
2012	185.9	80.5
2013	185.2	0

Before Tax Effect of Cash Flow Hedges on Consolidated Financial Statements

		Gain Recognized in Other Comprehensive Income (Effective Portion)
		For the years ended
		December 31,
Derivative Instrument		2011	2010
		(in thousands)
Fixed price swaps		$    714,740	$    166,722
Costless-collars		$    144,126	$    132,438
	Classification of Gain Reclassified from Accumulated Other	Gain Reclassified from Accumulated Other Comprehensive Income into Earnings (Effective Portion)
	Comprehensive Income	For the years ended
	into Earnings	December 31,
Derivative Instrument	(Effective Portion)	2011	2010
		(in thousands)
Fixed price swaps	Gas Sales	$    256,229	$    230,707
Costless-collars	Gas Sales	$      65,047	$      70,775
		Loss Recognized in Earnings (Ineffective Portion)
	Classification of Loss	For the years ended
	Recognized in Earnings	December 31,
Derivative Instrument	(Ineffective Portion)	2011	2010
		(in thousands)
Fixed price swaps	Gas Sales	$      (4,018)	$       (4,769)
Costless-collars	Gas Sales	$         (137)	$       (1,999)

Before Tax Effect of Basis Swaps Not Qualifying for Hedge Accounting

		Unrealized Gain Recognized in Earnings
	Income Statement	For the years ended
	Classification	December 31,
Derivative Instrument	of Unrealized Gain	2011	2010
		(in thousands)
Basis swaps	Gas Sales	$        5,222	$      11,434
		Realized Loss Recognized in Earnings
	Income Statement	For the years ended
	Classification	December 31,
Derivative Instrument	of Realized Loss	2011	2010
		(in thousands)
Basis swaps	Gas Sales	$      (2,135)	$     (12,098)