Derivative instruments (Tables)

12 Months Ended

Dec. 31, 2012

Derivative Instruments, Gain (Loss) [Line Items]

Schedule of derivative instruments, gain (losses) [Table Text Block]

The gains and losses on derivative instruments for the years ended December 31 were as follows:

	2012			2011			2010
	(In thousands)
Commodity derivatives designated as cash flow hedges:
Amount of gain (loss) recognized in accumulated other comprehensive loss (effective portion), net of tax	$	10,209		$	10,806		$	(3,077	)
Amount of gain (loss) reclassified from accumulated other comprehensive loss into operating revenues (effective portion), net of tax	8,788			—			(3,720		)
Amount of gain (loss) recognized in operating revenues (ineffective portion), before tax	(730		)	1,827			—
Interest rate derivatives designated as cash flow hedges:
Amount of loss recognized in accumulated other comprehensive loss (effective portion), net of tax	(1,712		)	(2,906		)	—
Amount of loss reclassified from accumulated other comprehensive loss into interest expense (effective portion), net of tax	(34		)	—			(30		)
Amount of gain (loss) recognized in interest expense (ineffective portion), before tax	—			—			—
Commodity derivatives not designated as hedging instruments:
Amount of gain recognized in operating revenues, before tax	106			—			—

Derivative instruments (Tables)

The location and fair value of the Company's derivative instruments on the Consolidated Balance Sheets were as follows:

Asset Derivatives	Location on Consolidated Balance Sheets	Fair Value at December 31, 2012		Fair Value at December 31, 2011
		(In thousands)
Designated as hedges:
Commodity derivatives	Commodity derivative instruments	$	18,084	$	27,687
	Other assets - noncurrent	—		2,768
		18,084		30,455
Not designated as hedges:
Commodity derivatives	Commodity derivative instruments	220		—
		220		—
Total asset derivatives		$	18,304	$	30,455

Liability Derivatives	Location on Consolidated Balance Sheets	Fair Value at December 31, 2012		Fair Value at December 31, 2011
		(In thousands)
Designated as hedges:
Commodity derivatives	Commodity derivative instruments	$	—	$	12,727
	Other liabilities - noncurrent	—		937
Interest rate derivatives	Other accrued liabilities	6,255		827
	Other liabilities - noncurrent	—		3,935
		6,255		18,426
Not designated as hedges:
Commodity derivatives	Commodity derivative instruments	—		437
		—		437
Total liability derivatives		$	6,255	$	18,863