CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 2,121	$ 1,056
Accounts receivable	63,734	67,516
Derivative instruments	16,461	40,190
Other current assets	8,905	16,318
Total current assets	91,221	125,080
Oil and natural gas properties, full cost method of accounting:
Proved, net of accumulated depletion of $8,369,028 and $8,237,186	1,312,337	1,459,312
Unproved	187,870	277,798
Net oil and natural gas properties	1,500,207	1,737,110
Other property and equipment, net of accumulated depreciation and amortization of $50,412 and $46,908	13,425	17,128
Net property and equipment	1,513,632	1,754,238
Deferred income taxes	6,221	14,681
Goodwill	239,420	239,420
Derivative instruments	3,039	8,335
Other assets	55,784	60,108
TOTAL ASSETS	1,909,317	2,201,862
Current liabilities:
Accounts payable and accrued liabilities	189,362	164,786
Accrued interest	23,567	23,407
Derivative instruments	5,467	9,347
Deferred income taxes	6,221	14,681
Current portion of long-term debt	0	12
Other current liabilities	14,904	14,092
Total current liabilities	239,521	226,325
Long-term debt	1,615,322	1,862,088
Asset retirement obligations	25,323	56,155
Derivative instruments	4,134	7,204
Other liabilities	88,107	92,914
Total liabilities	1,972,407	2,244,686
Shareholders’ equity:
Preferred stock, none issued and outstanding	0	0
Common stock, 119,757,396 and 118,245,320 shares issued and outstanding	11,976	11,825
Capital surplus	2,552,707	2,541,859
Accumulated deficit	(2,608,289)	(2,575,994)
Accumulated other comprehensive loss	(19,484)	(20,514)
Total shareholders’ equity (deficit)	(63,090)	(42,824)
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 1,909,317	$ 2,201,862