Consolidated Statements of Cash Flows (Audited) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:	$ (22,301)	$ (130,712)	$ 13,437
Net income (loss)	(22,301)	(130,712)	13,437
Adjustments to net income (loss) to reconcile to net cash provided by operating activities:
Net change in fair value of unsettled derivatives	36,801	17,134	(28,601)
Depreciation, depletion and amortization	129,518	146,879	135,154
Impairment of natural gas and crude oil properties	53,438	168,149	25,159
Prepaid well write-offs	74	3,916	1,359
Loss on extinguishment of debt	0	23,283	0
Exploratory dry hole costs	0	15,347	177
Accretion of asset retirement obligation	4,747	4,060	1,897
Stock-based compensation	12,880	8,495	8,781
Excess tax benefits from stock-based compensation	(2,489)	0	(1,311)
(Gain) loss from sale of properties and equipment	(3,722)	24,273	4,263
Amortization of debt discount and issuance costs	6,783	7,864	6,265
Deferred income taxes	(15,883)	(80,379)	9,530
Inventory adjustment and other	460	4,123	135
Total adjustments to net income (loss) to reconcile to net cash provided by operating activities:	230,051	294,598	154,282
Changes in current assets and liabilities:
Accounts receivable	(41,509)	6,843	(3,451)
Other assets	3,461	(2,908)	(3,893)
Restricted cash	(8)	8,859	(8,603)
Production tax liability	4,121	2,499	5,436
Accounts payable and accrued expenses	(11,485)	(5,050)	12,422
Other liabilities	(3,165)	592	(2,796)
Total changes in current assets and liabilities	(48,585)	10,835	(885)
Net cash provided by operating activities	159,165	174,721	166,834
Cash flows from investing activities:
Capital expenditures	(394,948)	(347,729)	(334,496)
Acquisition of natural gas and crude oil properties, net of cash acquired	(9,658)	(312,223)	(145,894)
Proceeds from acquisition adjustments	7,579	14,469	0
Proceeds from sale of properties and equipment	179,919	193,544	23,140
Other	0	0	849
Net cash used in investing activities	(217,108)	(451,939)	(456,401)
Cash flows from financing activities:
Proceeds from credit facility	260,250	682,000	417,194
Payment of credit facility	283,500	839,750	183,713
Proceeds from senior notes	0	500,000	0
Repurchase of senior notes	0	(221,840)	0
Payment of debt issuance costs	(2,352)	(11,969)	(680)
Proceeds from sale of equity, net of issuance costs	275,847	164,496	0
Excess tax benefits from stock-based compensation	2,489	0	1,311
Contribution by investing partner in PDCM	0	0	12,464
Purchase of treasury stock	(4,133)	(1,500)	(3,143)
Proceeds from exercise of stock options	128	0	0
Net cash provided by (used in) financing activities	248,729	271,437	243,433
Net increase (decrease) in cash and cash equivalents	190,786	(5,781)	(46,134)
Cash and cash equivalents, beginning of period	2,457	8,238	54,372
Cash and cash equivalents, end of period	193,243	2,457	8,238
Cash payments (receipts) for:
Interest, net of capitalized interest	48,844	41,768	29,429
Income taxes	(3,014)	1,845	(1,498)
Non-cash investing activities:
Change in accounts payable related to purchases of properties and equipment	33,328	288	23,837
Change in asset retirement obligation, with a corresponding increase to natural gas and crude oil properties, net of disposals	2,112	11,967	17,538
Change in accounts receivable related to disposition of properties and equipment	808	0	0
Change in other assets related to disposition of properties and equipment	$ 3,350	$ 0	$ 0