Consolidated Statements of Cash Flows (Audited) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash flows from operating activities:
Net income (loss)	$ 13,437	$ 5,934	$ (81,093)
Adjustments to net income (loss) to reconcile to net cash provided by operating activities:
Unrealized loss (gain) loss on derivatives, net	(28,601)	(12,625)	116,623
Depreciation, depletion and amortization	135,154	111,062	131,004
Impairment of natural gas and crude oil properties	25,159	11,147	8,205
Exploratory dry hole costs	177	4,199	1,059
Accretion of asset retirement obligation	1,897	1,423	1,368
Stock-based compensation	8,781	5,314	5,935
Excess tax benefits from stock-based compensation	(1,311)	(293)	0
Loss (gain) from sale of properties and equipment	(4,263)	299	(105)
Amortization of debt discount and issuance costs	6,265	4,618	5,302
Deferred income taxes	9,530	1,179	(18,084)
Total adjustments to net income (loss) to reconcile to net cash provided by operating activities:	152,788	126,323	251,307
Changes in current assets and liabilities:
Decrease (increase) in restricted cash	(8,603)	219	15,564
Decrease (increase) in accounts receivable	(3,451)	2,122	13,197
Decrease (increase) in other current assets	(2,399)	23,591	3,032
Increase (decrease) in production tax liability	5,436	(6,818)	(4,541)
Increase (decrease) in accounts payable and accrued expenses	12,422	1,172	(22,482)
Decrease in other current liabilities	(2,796)	(730)	(31,089)
Total changes in current assets and liabilities	609	19,556	(26,319)
Net cash provided by operating activities	166,834	151,813	143,895
Cash flows from investing activities:
Capital expenditures	(334,496)	(162,723)	(143,033)
Acquisition of natural gas and crude oil properties, net of cash acquired	(145,894)	(158,051)	0
Proceeds from sale of properties and equipment	23,140	23,369	755
Other	849	(3,527)	0
Net cash used in investing activities	(456,401)	(300,932)	(142,278)
Cash flows from financing activities:
Proceeds from credit facility	417,194	414,500	285,086
Proceeds from senior notes	0	115,000	0
Payment of credit facility	(183,713)	(494,500)	(399,586)
Payment of debt issuance costs	(680)	(8,541)	(9,249)
Proceeds from sale of equity, net of issuance costs	0	125,506	48,490
Excess tax benefits from stock-based compensation	1,311	293	0
Contribution by investing partner in PDCM	12,464	20,077	55,000
Purchase of treasury stock	(3,143)	(788)	(364)
Net cash provided by (used in) financing activities	243,433	171,547	(20,623)
Net increase (decrease) in cash and cash equivalents	(46,134)	22,428	(19,006)
Cash and cash equivalents, beginning of period	54,372	31,944	50,950
Cash and cash equivalents, end of period	8,238	54,372	31,944
Cash payments (receipts) for:
Interest, net of capitalized interest	29,429	28,335	32,014
Income tax refunds, net of income taxes	(1,498)	(27,322)	(3,355)
Non-cash investing activities:
Change in accounts payable related to purchases of properties and equipment	23,837	15,787	(36,765)
Change in asset retirement obligation, with a corresponding increase to natural gas and crude oil properties, net of disposals	17,538	3,624	5,110
Change in paid-in capital related to convertible debt, net of tax	$ 0	$ 12,850	$ 0