Segment Information Reconciliation of Segment Information, Income (Loss) From Continuing Operations Before Income Tax (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Segment Income (Loss) Before Income Taxes for reportable business segments	$ 759,240	$ (138,429)
Other Income (Expense)	6,493	(4,075)
Gain on Sale of Assets	11,342	3,996
Loss on debt extinguishment	(15,635)	822
Income (Loss) From Continuing Operations Before Income Tax	759,240	(138,429)
Operating Segments [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Segment Income (Loss) Before Income Taxes for reportable business segments	135,343	(135,176)
Income (Loss) From Continuing Operations Before Income Tax	135,343	(135,176)
Operating Segments [Member] \| Marcellus Shale [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Segment Income (Loss) Before Income Taxes for reportable business segments	44,242	29,969
Income (Loss) From Continuing Operations Before Income Tax	44,242	29,969
Operating Segments [Member] \| Utica Shale [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Segment Income (Loss) Before Income Taxes for reportable business segments	56,107	17,807
Income (Loss) From Continuing Operations Before Income Tax	56,107	17,807
Operating Segments [Member] \| Coalbed Methane [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Segment Income (Loss) Before Income Taxes for reportable business segments	13,117	3,608
Income (Loss) From Continuing Operations Before Income Tax	13,117	3,608
Operating Segments [Member] \| Other Gas [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Segment Income (Loss) Before Income Taxes for reportable business segments	(13,657)	(186,560)
Income (Loss) From Continuing Operations Before Income Tax	(13,657)	(186,560)
Corporate, Non-Segment [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Segment Income (Loss) Before Income Taxes for reportable business segments	623,897
Other Income (Expense)	6,493	(4,075)
Gain on Sale of Assets	9,376	0
Gain on Previously Held Equity Interest	623,663	0
Loss on debt extinguishment	(15,635)	822
Income (Loss) From Continuing Operations Before Income Tax	623,897
Total E&P [Member] \| Operating Segments [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Segment Income (Loss) Before Income Taxes for reportable business segments	99,809	(135,176)
Income (Loss) From Continuing Operations Before Income Tax	99,809	(135,176)
Midstream [Member] \| Operating Segments [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Segment Income (Loss) Before Income Taxes for reportable business segments	35,534	0
Income (Loss) From Continuing Operations Before Income Tax	$ 35,534	0
Midstream [Member] \| Corporate, Non-Segment [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total Segment Income (Loss) Before Income Taxes for reportable business segments		(3,253)
Income (Loss) From Continuing Operations Before Income Tax		$ (3,253)

Amount of gain (loss) on sale or disposal of an equity method investment.

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Amount of gain (loss) on sale or disposal of assets, including but not limited to property plant and equipment, intangible assets and equity in securities of subsidiaries or equity method investee.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
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-Section 45
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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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The portion of earnings or loss from continuing operations before income taxes that is attributable to domestic operations.

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-Name Accounting Standards Codification
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Amount of income (expense) related to nonoperating activities, classified as other.

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