CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Current assets
Cash and cash equivalents	$ 7,512	$ 120,911
Accounts receivable, net of allowance for doubtful accounts	72,432	72,378
Derivative assets	18,987	16,818
Income taxes receivable	31,465
Other current assets	14,950	4,233
Total current assets	145,346	214,340
Property and equipment, net (successful efforts method)	1,777,575	1,705,584
Derivative assets		3,889
Other assets	20,132	20,787
Total assets	1,943,053	1,944,600
Current liabilities
Accounts payable and accrued liabilities	94,504	99,661
Derivative liabilities	3,549	388
Deferred income taxes	3,808	4,318
Income taxes payable		2,627
Current portion of long-term debt	4,746
Total current liabilities	106,607	106,994
Other liabilities	15,887	19,958
Derivative liabilities	6,850
Deferred income taxes	274,839	330,836
Long-term debt	692,561	506,536
Commitments and contingencies (Note 12)
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 45,714,191 and 45,556,854 as of December 31, 2011 and December 31, 2010, respectively	270	267
Paid-in capital	690,131	680,981
Retained earnings	157,242	300,473
Deferred compensation obligation	3,620	2,743
Accumulated other comprehensive loss	(1,084)	(938)
Treasury stock - 223,886 and 125,357 shares of common stock, at cost, as of December 31, 2011 and December 31, 2010, respectively	(3,870)	(3,250)
Total shareholders' equity	846,309	980,276
Total liabilities and shareholders' equity	$ 1,943,053	$ 1,944,600