CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities
Net loss	$ (140,721)	$ (50,148)
Adjustments to reconcile net loss to net cash provided by operating activities:
Gain Loss On Extinguishment Of Debt Before Transaction Costs	29,157	3,144
Loss on long-term purchase commitment	0	17,332
Depreciation, depletion and amortization	178,355	151,888
Impairments	132,224	29,316
Derivative contracts:
Net losses (gains)	23,208	(31,250)
Cash settlements	1,625	24,189
Deferred income tax benefit	(75,577)	(32,444)
Loss (gain) on sales of assets, net	479	(2,407)
Non-cash exploration expense	14,167	24,765
Non-cash interest expense	2,846	3,107
Share-based compensation (equity-classified)	4,781	4,233
Other, net	1,461	302
Changes in operating assets and liabilities	52,829	48,187
Net cash provided by operating activities	224,834	190,214
Payments to Acquire Businesses, Net of Cash Acquired	(358,239)	0
PaymentsToSettleObligationsAssumedInAcquisitionNet	(43,023)	0
Cash flows from investing activities
Capital expenditures - property and equipment	(356,964)	(257,194)
Proceeds from sales of assets, net	653	93,276
Payments for (Proceeds from) Other Investing Activities	0	180
Net cash used in investing activities	(757,573)	(163,738)
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	219,000	181,000
Repayment of revolving credit facility borrowings	(91,000)	(203,000)
Payments of Debt Issuance Costs	(25,199)	(1,779)
Dividends paid on preferred stock	(5,137)	0
Dividends paid on common stock	0	(5,176)
Other, net	(164)	0
Net cash provided by (used in) financing activities	553,410	(28,955)
Net increase (decrease) in cash and cash equivalents	20,671	(2,479)
Cash and cash equivalents - beginning of period	17,650	7,512
Cash and cash equivalents - end of period	38,321	5,033
Cash paid for:
Interest (net of amounts capitalized)	20,671	27,865
Income taxes (net of refunds received)	0	(32,574)
Noncash or Part Noncash Acquisition, Other Assets Acquired	52,794	0
Noncash or Part Noncash Acquisition, Other Liabilities Assumed	63,952	0
Stock Issued During Period, Value, Acquisitions	$ 42,300	$ 0