CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 184	$ 119,194
Accounts receivable	209,633	210,368
Refundable income taxes	2,603	5,581
Prepaid expenses and other	46,812	68,026
Derivative asset	69,207	55,813
Deferred income taxes	5,798	4,222
Total current assets	334,237	463,204
Property and equipment (successful efforts method), at cost:
Land	1,845	1,548
Proved Oil and Gas Property, Successful Effort Method	4,869,603	4,378,987
Less - accumulated depletion, depreciation, and amortization	(2,034,929)	(1,766,445)
Unproved Oil and Gas Property, Successful Effort Method	122,005	120,966
Wells in progress	274,690	273,428
Materials inventory, at lower of cost or market	12,966	16,537
Oil and gas properties held for sale (note 3)	60,711	246
Other property and equipment, net of accumulated depreciation	120,058	71,369
Total property and equipment, net	3,426,949	3,096,636
Other noncurrent assets:
Derivative asset	44,270	31,062
Restricted Cash and Cash Equivalents, Noncurrent	109,486	124,703
Other noncurrent assets	84,629	83,375
Total other noncurrent assets	238,385	239,140
Total Assets	3,999,571	3,798,980
Current liabilities:
Accounts payable and accrued expenses	460,611	456,999
Derivative liability	9,150	42,806
Deposit associated with oil and gas properties held for sale	6,000	6,000
Total current liabilities	475,761	505,805
Noncurrent liabilities:
Long-term credit facility	61,000	0
3.50% Senior Convertible Notes, net of unamortized discount	0	285,069
6.625% Senior Notes due 2019	350,000	350,000
6.50% Senior Notes due 2021	350,000	350,000
6.50% Senior Notes due 2023	400,000	0
Asset retirement obligation	89,027	87,167
Asset retirement obligation associated with oil and gas properties held for sale (note 3)	1,732	1,277
Net Profits Plan liability	89,591	107,731
Deferred income taxes	596,725	568,263
Derivative liability	956	12,875
Other noncurrent liabilities	57,083	67,853
Total noncurrent liabilities	1,996,114	1,830,235
Commitments and contingencies (note 7)
Stockholders' equity:
Common stock, $0.01 par value	652	641
Additional paid-in capital	234,562	216,966
Treasury stock at cost	(1,263)	(1,544)
Retained earnings	1,299,175	1,251,157
Accumulated other comprehensive loss	(5,430)	(4,280)
Total stockholders' equity	1,527,696	1,462,940
Total Liabilities and Stockholders' Equity	$ 3,999,571	$ 3,798,980