Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Current Assets:
Cash and cash equivalents	$ 126,789	$ 251,696
Accounts receivable	61,199	64,392
Deferred tax asset	2,600	6,603
Other current assets	9,437	5,460
Total Current Assets	200,025	328,151
Property and Equipment:
Property and Equipment	4,648,687	4,466,845
Less - Accumulated depreciation, depletion, and amortization	(2,660,839)	(2,599,079)
Property and Equipment, Net	1,987,848	1,867,766
Other Long-Term Assets	15,752	16,552
Total Assets	2,203,625	2,212,469
Current Liabilities:
Accounts payable and accrued liabilities	78,798	95,966
Accrued capital costs	95,566	98,844
Accrued interest	11,865	12,459
Undistributed oil and gas revenues	6,448	4,525
Total Current Liabilities	192,677	211,794
Long-Term Debt	719,875	719,775
Deferred Tax Liabilities	205,025	206,567
Asset Retirement Obligation	69,552	67,115
Other Long-Term Liabilities	10,853	10,709
Commitments and Contingencies
Stockholders' Equity:
Preferred stock, $.01 par value, 5,000,000 shares authorized, none outstanding
Common stock, $.01 par value, 150,000,000 shares authorized, 43,341,063 and 42,969,546 shares issued, and 42,828,821 and 42,485,075 shares outstanding, respectively	433	430
Additional paid-in capital	733,592	726,956
Treasury stock held, at cost, 512,242 and 484,471 shares, respectively	(13,686)	(12,350)
Retained earnings	285,043	281,473
Accumulated other comprehensive income, net of income tax	261
Total Stockholders' Equity	1,005,643	996,509
Total Liabilities and Stockholders' Equity	$ 2,203,625	$ 2,212,469