CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities
Net loss	$ (41,821)	$ (17,537)
Adjustments to reconcile net loss to net cash provided by operating activities:
Gain Loss On Extinguishment Of Debt Before Transaction Costs	29,157	0
Depreciation, depletion and amortization	115,905	102,557
Impairments	0	28,616
Derivative contracts:
Net gains	(827)	(43,521)
Cash settlements	5,790	14,951
Deferred income tax benefit	(22,471)	(10,236)
Loss (gain) on sales of assets, net	293	(834)
Non-cash exploration expense	10,408	16,455
Non-cash interest expense	1,885	2,050
Share-based compensation (equity-classified)	3,771	2,951
Other, net	938	203
Changes in operating assets and liabilities	26,723	20,070
Net cash provided by operating activities	129,751	115,725
Payments to Acquire Businesses, Net of Cash Acquired	(358,239)	0
PaymentsToSettleObligationsAssumedInAcquisitionNet	(36,310)	0
Cash flows from investing activities
Capital expenditures - property and equipment	(229,319)	(188,236)
Proceeds from sales of assets, net	867	527
Payments for (Proceeds from) Other Investing Activities	0	180
Net cash used in investing activities	(623,001)	(187,529)
Proceeds from Issuance of Senior Long-term Debt	775,000	0
Early Repayment of Senior Debt	(319,090)	0
Cash flows from financing activities
Proceeds from revolving credit facility borrowings	153,000	84,000
Repayment of revolving credit facility borrowings	(86,000)	(3,000)
Payments of Debt Issuance Costs	(24,698)	0
Dividends paid on preferred stock	(3,412)	0
Dividends paid on common stock	0	(5,176)
Other, net	(110)	0
Net cash provided by financing activities	494,690	75,824
Net increase in cash and cash equivalents	1,440	4,020
Cash and cash equivalents - beginning of period	17,650	7,512
Cash and cash equivalents - end of period	19,090	11,532
Cash paid for:
Interest (net of amounts capitalized)	23,215	26,656
Income taxes (net of refunds received)	0	(311)
Noncash or Part Noncash Acquisition, Other Assets Acquired	50,826	0
Noncash or Part Noncash Acquisition, Other Liabilities Assumed	20,323	0
Stock Issued During Period, Value, Acquisitions	$ 42,300	$ 0