Discontinued Operations - Additional Information (Detail) - HighMount [Member] $ in Millions	12 Months Ended
Dec. 31, 2014 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment of natural gas and oil properties	$ 29
Impairment of natural gas and oil properties after tax	19
Effects of cash flow hedges not considered in calculating ceiling limitation, impairments	29
Effects of cash flow hedges not considered in calculating ceiling limitation after tax, impairments	$ 18

Disposal Group Including Discontinued Operation Expenses Impairment Of Natural Gas And Oil Properties

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- Definition

Disposal Group Including Discontinued Operation Expenses Impairment Of Natural Gas And Oil Properties Net Of Tax

+ References

No definition available.

+ Details

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- Definition

Effects Of Cash Flow Hedges Not Considered In Calculating Ceiling Limitation Amount Net Of Tax

+ References

No definition available.

+ Details

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- Definition

Amount that would have been charged to income had the effects of the cash flow hedges not been considered in calculating the ceiling limitation at an oil and gas producing company subject to the full cost rules.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 360
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 12.D.3(b))
-URI http://asc.fasb.org/extlink&oid=27015634&loc=d3e516453-122869

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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