Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Cash flows from operating activities
Net income (loss)	$ 9,782	$ (40,264)
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Depreciation, depletion and amortization	36,932	33,977
Deferred income taxes	6,161	(22,159)
Reclassification adjustment for hedge (gains) losses included in net income (loss)	(12,423)	6,755
Non-hedge derivative losses	10,463	60,926
Loss on extinguishment of debt	0	20,576
Loss on sale of assets	95	5
Other	751	732
Change in assets and liabilities
Accounts receivable	(1,830)	(7,281)
Inventories	(4,367)	1,026
Prepaid expenses and other assets	1,559	1,457
Accounts payable and accrued liabilities	(4,539)	7,942
Revenue distribution payable	(2,792)	2,258
Stock-based compensation	1,089	1,066
Net cash provided by operating activities	40,881	67,016
Cash flows from investing activities
Purchase of property and equipment and oil and natural gas properties	(98,403)	(88,518)
Proceeds from dispositions of property and equipment and oil and natural gas properties	1,856	211
Settlement of non-hedge derivative instruments	2,257	(5,294)
Other	22	0
Net cash used in investing activities	(94,268)	(93,601)
Cash flows from financing activities
Proceeds from long-term debt	42,176	1,059
Repayment of long-term debt and capital lease obligations	(877)	(1,275)
Proceeds from Senior Notes	0	400,000
Repayment of Senior Notes	0	(325,000)
Payment of debt issuance costs and other financing fees	0	(8,597)
Payment of debt extinguishment costs	0	(15,085)
Net cash provided by financing activities	41,299	51,102
Net increase (decrease) in cash and cash equivalents	(12,088)	24,517
Cash and cash equivalents at beginning of period	34,589	55,111
Cash and cash equivalents at end of period	$ 22,501	$ 79,628