Natural Gas And Oil Producing Activities (Unaudited) (Schedule Of Capitalized Costs Of Unproved Properties Excluded From Amortization) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended	96 Months Ended	132 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2014
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Property aquisition costs	$ 3,892us-gaap_AcquisitionCosts	$ 87us-gaap_AcquisitionCosts	$ 75us-gaap_AcquisitionCosts	$ 142us-gaap_AcquisitionCosts	$ 4,196us-gaap_AcquisitionCosts
Exploration and Development Costs	239swn_ExplorationAndDevelopmentCosts	40swn_ExplorationAndDevelopmentCosts	26swn_ExplorationAndDevelopmentCosts	61swn_ExplorationAndDevelopmentCosts	366swn_ExplorationAndDevelopmentCosts
Capitalized interest	13	10	14	47	84
Capitalized Costs of Unproved Properties Excluded from Amortization, Period Cost, Total	4,144	137	115	250	4,646
Exploration Program in Canada [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Capitalized Costs of Unproved Properties Excluded from Amortization, Period Cost, Total	76
Composition of Net Unevaluated Costs [Member] \| Exploration Program in Canada [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Property aquisition costs					36
Exploration and Development Costs					31
Capitalized interest					$ 9

Capitalized Interest of Net Unevaluated Costs Excluded From Amortization

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- Definition

Costs incurred related to Exploration and Development activities.

+ References

No definition available.

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- Definition

The capitalized costs incurred during the period (excluded from amortization) to purchase, lease or otherwise acquire an unproved property, including costs of lease bonuses and options to purchase or lease properties, the portion of costs applicable to minerals when land including mineral rights is purchased in fee, brokers' fees, recording fees, legal costs, and other costs incurred in acquiring properties.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 932

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-10.(c)(7)(ii))

-URI http://asc.fasb.org/extlink&oid=27015464&loc=d3e511914-122862

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 10

-Paragraph c

-Subparagraph 3(ii)(A)

-Article 4

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- Definition

The sum of the capitalized costs incurred during the period of unproved properties excluded from amortization including acquisition costs, exploration costs, development costs, and production costs.

+ References

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