Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Operating Activities
Net Income (Loss)	$ (354,925)	$ 502,614
Income from discontinued operations	0	(469,490)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	434,005	399,568
Asset impairment	466,390	181,500
Accretion of discount on asset retirement obligations	5,379	5,650
Deferred income taxes	(217,943)	287,855
Change in derivative fair value	139,490	(53,928)
(Gain) loss on sale of assets	(27,558)	105
Stock-based compensation expense	7,158	10,837
Exploration, including dry holes	6,967	8,382
Discontinued operations	0	112,180
Other, net	7,080	(1,972)
Net change in:
Accounts receivable	81,285	(28,486)
Inventories	(3,933)	(3,243)
Accounts payable	(30,871)	27,967
Accrued taxes/income tax receivable	25,339	(264,108)
Pension and other postretirement benefit contributions	(10,932)	(2,397)
Other current assets and liabilities	(4,996)	(3,746)
Net cash provided by operating activities	521,935	709,288
Investing Activities
Additions to oil and natural gas properties	(960,966)	(906,166)
Acquisitions, net of cash acquired	(62,805)	(26,371)
Proceeds from the sale of assets	393,174	1,347,904
Purchase of short-term investments	(919,000)	(377,000)
Sale of short-term investments	919,000	359,000
Discontinued operations	0	(51,850)
Net cash provided by (used in) investing activities	(630,597)	345,517
Financing Activities
Payment of dividends on common stock	(4,499)	(32,840)
Issuance of common stock	399,593	23,053
Reduction of long-term debt	0	(600,000)
Payment of debt issuance costs	0	(7,912)
Net change in credit facility	(288,500)	(410,100)
Tax benefit on stock compensation	917	3,873
Discontinued operations	0	(35,113)
Net cash provided by (used in) financing activities	107,511	(1,059,039)
Net change in cash and cash equivalents	(1,151)	(4,234)
Cash and cash equivalents at beginning of period	1,852	5,555
Cash and cash equivalents at end of period	$ 701	$ 1,321