Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2013

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]

Fair value hierarchy of financial assets and liabilities

The following table sets forth by level within the fair value hierarchy our financial assets and liabilities that were accounted for at fair value on a recurring basis as of the periods indicated:

	Fair Value Measurements Using:
In thousands	Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (Level 3)		Total
March 31, 2013
Assets:
Oil derivative contracts	$	—	$	4,376		$	—	$	4,376
Liabilities:
Oil derivative contracts	—		(23,232		)	—		(23,232		)
Total	$	—	$	(18,856	)	$	—	$	(18,856	)
December 31, 2012
Assets:
Oil derivative contracts	$	—	$	19,513		$	—	$	19,513
Liabilities:
Oil derivative contracts	—		(26,440		)	—		(26,440		)
Total	$	—	$	(6,927	)	$	—	$	(6,927	)