CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Revenues:
Oil, natural gas, and natural gas liquids sales	$ 118,042	$ 158,901
Interest and other	132	32
Total revenues	118,174	158,933
Costs, expenses, and other:
Lease operating expenses	21,204	27,607
Production and property taxes	2,216	11,153
Transportation and processing costs	3,280	3,972
General and administrative	20,014	15,384
Depreciation, depletion, and amortization	48,543	66,970
Ceiling test write-down of natural gas properties	0	34,817
Interest expense	36,128	33,392
Realized and unrealized losses (gains) on derivative instruments, net	25,580	(29,524)
Other, net	28,820	26,920
Total costs, expenses, and other	185,785	190,691
Loss before income taxes	(67,611)	(31,758)
Income tax	337	915
Net loss	$ (67,948)	$ (32,673)
Basic loss per common share (in dollars per share)	$ (0.59)	$ (0.29)
Diluted loss per common share (in dollars per share)	$ (0.59)	$ (0.29)