Natural Gas And Oil Producing Activities (Unaudited) (Schedule Of Analysis Of Changes In Standardized Measure) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Natural Gas And Oil Producing Activities (Unaudited) [Abstract]
Standardized measure, beginning of year	$ 3,736	$ 2,051	$ 3,451
Sales and transfers of natural gas and oil produced, net of production costs	(2,084)	(1,774)	(1,444)
Net changes in prices and production costs	1,192	1,853	(2,605)
Extensions, discoveries, and other additions, net of future production and development costs	1,049	1,454	550
Acquisition of reserves in place	1,897	5
Sales of reserves in place			(157)
Revisions of previous quantity estimates	622	349	(1,109)
Accretion of discount	513us-gaap_AccretionOfDiscount	232us-gaap_AccretionOfDiscount	480us-gaap_AccretionOfDiscount
Net change in income taxes	(522)	(1,120)	1,079
Changes in estimated future development costs	110	(196)	2,476
Previously estimated development costs incurred during the year	815	223	62
Changes in production rates (timing) and other	215swn_ChangesInProductionRatesAndOther	659swn_ChangesInProductionRatesAndOther	(732)swn_ChangesInProductionRatesAndOther
Standardized measure, end of year	$ 7,543	$ 3,736	$ 2,051

Changes In Production Rates (Timing) and Other.

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