Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash flows from operating activities:
Net (loss) earnings	$ (228,063)	$ 82,524	$ 54,030
Depreciation, depletion and amortization	215,822	182,657	145,788
Gain on purchase	(1,046)	0	0
Extinguishment of debt	4,072	573	10,823
Amortization of debt issuance costs and net discount	8,243	8,481	6,827
Impairment of oil and natural gas properties	625,564	0	10,654
Dry hole and impairment	4,616	1,478	4,205
Derivatives	(29,094)	42,609	247
Stock-based compensation expense	9,636	9,386	8,626
Deferred income taxes	(149,279)	54,698	19,998
Loss on sale of asset	0	0	79
Other, net	3,223	(12)	(4,016)
Cash paid for abandonment	(1,803)	(1,832)	(1,030)
Bad debt recovery	0	(38,508)	0
Change in book overdraft	(156)	528	(16,018)
Changes in operating assets and liabilities:
Accounts receivable	(23,526)	20,055	(11,816)
Inventories, prepaid expenses, and other current assets	(2,768)	(7,553)	1,761
Accounts payable and revenue and royalties payable	25,019	5,273	(49,119)
Accrued interest and other accrued liabilities	(4,561)	6,880	31,537
Net cash provided by operating activities	455,899	367,237	212,576
Cash flows from investing activities:
Exploration and development of oil and natural gas properties	(527,112)	(310,139)	(134,946)
Property acquisitions	(158,090)	(334,409)	(13,497)
Capitalized interest	(29,117)	(28,321)	(30,107)
Proceeds from sale of assets	0	0	139,796
Deposits on asset sales	3,300	0	0
Net cash used in investing activities	(711,019)	(672,869)	(38,754)
Cash flows from financing activities:
Proceeds from issuances on line of credit	406,600	316,000	387,700
Payments on line of credit	(411,900)	(310,700)	(413,000)
Proceeds from issuance of 10.25% senior notes due 2014	0	0	434,962
Proceeds from issuance of 6.75% senior notes due 2020	0	300,000	0
Repurchase of 10.25% Senior notes due 2014	(94,744)	0	0
Proceeds from long-term borrowings under credit facility	719,700	363,000	655,300
Repayments of long-term borrowings under credit facility	(358,200)	(565,000)	(1,215,100)
Financing obligation	(380)	(346)	18,214
Debt issuance costs	(2,250)	(15,173)	(23,955)
Dividends paid	(16,846)	(16,181)	(13,664)
Proceeds from issuance of stock	0	224,313	0
Proceeds from stock option exercises	10,113	4,402	890
Excess income tax benefit (expense)	3,047	284	(98)
Net cash provided by (used in) financing activities	255,140	300,599	(168,751)
Net increase (decrease) in cash and cash equivalents	20	(5,033)	5,071
Cash and cash equivalents at beginning of year	278	5,311	240
Cash and cash equivalents at end of year	298	278	5,311
Supplemental disclosures of cash flow information:
Interest paid, net of capitalized interest	59,853	40,773	36,854
Incomes taxes paid (refunded)	7,914	(285)	8,769
Noncash investing activities:
Accrued capital expenditures	61,098	51,095	5,059
Asset retirement obligations	$ 7,448	$ 3,721	$ 1,407