CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
ASSETS
Cash and cash equivalents	$ 119,194	$ 5,077
Accounts receivable (Note 2)	210,368	163,190
Refundable income taxes	5,581	8,482
Prepaid expenses and other	68,026	45,522
Derivative asset	55,813	43,491
Deferred income taxes	4,222	8,883
Total current assets	463,204	274,645
Land	1,548	1,491
Proved oil and gas properties	4,378,987	3,389,158
Less - accumulated depletion, depreciation, and amortization	(1,766,445)	(1,326,932)
Unproved oil and gas properties	120,966	94,290
Wells in progress	273,428	145,327
Materials inventory, at lower of cost or market	16,537	22,542
Other Assets Held-for-sale	246	86,811
Other property and equipment, net of accumulated depreciation of $18,394 in 2011 and $15,480 in 2010	71,369	21,365
Total property and equipment, net	3,096,636	2,434,052
Derivative Instruments and Hedges, Noncurrent	31,062	18,841
Restricted Cash and Cash Equivalents, Noncurrent	124,703	0
Other noncurrent assets	83,375	16,783
Total other noncurrent assets	239,140	35,624
Total Assets	3,798,980	2,744,321
LIABILITIES
Accounts payable and accrued expenses	456,999	417,654
Derivative liability	42,806	82,044
Deposit associated with oil and gas properties held for sale	6,000	2,355
Total current liabilities	505,805	502,053
Long-term credit facility	0	48,000
3.50% Senior Convertible Notes, net of unamortized discount of $4,861 in 2011 and $11,827 in 2010	285,069	275,673
Senior Notes, 6.625%, Noncurrent	350,000	0
Senior Notes, 6.50%, Noncurrent	350,000	0
Asset retirement obligation	87,167	69,052
Asset retirement obligation associated with oil and gas properties held for sale	1,277	2,119
Net Profits Plan Liability (Note 11)		135,850
Deferred income taxes	568,263	443,135
Derivative Liabilities, Noncurrent	12,875	32,557
Other noncurrent liabilities	67,853	17,356
Total noncurrent liabilities	1,830,235	1,023,742
STOCKHOLDERS' EQUITY
Common stock, $0.01 par value - authorized: 200,000,000 shares; issued: 64,079,885 shares in 2011 and 63,412,800 shares in 2010; outstanding, net of treasury shares: 63,998,818 shares in 2011 and 63,310,165 shares in 2010	641	634
Additional paid-in capital	216,966	191,674
Treasury stock, at cost: 81,067 shares in 2011 and 102,635 shares in 2010	(1,544)	(423)
Retained earnings	1,251,157	1,042,123
Accumulated other comprehensive loss	(4,280)	(15,482)
Total stockholders' equity	1,462,940	1,218,526
Total Liabilities and Stockholders' Equity	$ 3,798,980	$ 2,744,321