CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Current assets
Cash and cash equivalents	$ 3,577	$ 120,911
Accounts receivable, net of allowance for doubtful accounts	75,736	72,378
Derivative assets	18,336	16,818
Other current assets	4,206	4,233
Total current assets	101,855	214,340
Property and equipment, net (successful efforts method)	1,752,261	1,705,584
Derivative assets	1,508	3,889
Other assets	21,383	20,787
Total assets	1,877,007	1,944,600
Current liabilities
Accounts payable and accrued liabilities	98,303	99,661
Derivative liabilities		388
Deferred income taxes	3,113	4,318
Income taxes payable	3,506	2,627
Total current liabilities	104,922	106,994
Other liabilities	15,657	19,958
Deferred income taxes	269,082	330,836
Long-term debt	612,983	506,536
Commitments and contingencies (Note 10)
Shareholders' equity:
Preferred stock of $100 par value - 100,000 shares authorized; none issued
Common stock of $0.01 par value - 128,000,000 shares authorized; shares issued of 45,706,545 and 45,556,854 as of September 30, 2011 and December 31, 2010, respectively	269	267
Paid-in capital	687,552	680,981
Retained earnings	187,761	300,473
Deferred compensation obligation	3,428	2,743
Accumulated other comprehensive loss	(836)	(938)
Treasury stock - 195,307 and 125,357 shares of common stock, at cost, as of September 30, 2011 and December 31, 2010, respectively	(3,811)	(3,250)
Total shareholders' equity	874,363	980,276
Total liabilities and shareholders' equity	$ 1,877,007	$ 1,944,600