Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2012

Fair Value Measurements [Abstract]

Schedule of Fair Value Measurements of Assets and Liabilities

	December 31,
	2012		2011
	(in thousands)
Assets:
Fair value of commodity derivative instruments	$	3,513	$	587
Liabilities:
Fair value of commodity derivative instruments	$	13,663	$	1,246

Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block]

	December 31, 2012					December 31, 2011
	(In thousands)
		Carrying Value		Estimated Fair Value		Carrying Value		Estimated Fair Value
2011 Notes	$	205,125	$	214,700	$	204,390	$	202,700
2012 Notes		289,786		309,900		-		-
Senior Credit Facility		195,000		195,000		-		-
Total	$	689,911	$	719,600	$	204,390	$	202,700