Natural Gas And Oil Producing Activities (Unaudited) (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended				96 Months Ended	132 Months Ended
	Dec. 31, 2014 ft3 acre	Dec. 31, 2013 ft3 acre	Dec. 31, 2012 ft3	Dec. 31, 2011 ft3	Dec. 31, 2011	Dec. 31, 2014
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Discount rate of natural gas and oil reserves	10.00%
Net unevaluated costs excluded from amortization	$ 4,144	$ 137	$ 115		$ 250	$ 4,646
Percentage of present worth of proved reserves evaluated in audit	97.00%	95.00%	93.00%
Capitalized interest based on weighted average cost of borrowings	55	62	62
Capitalized internal costs related to acquisition, exploration and development	320	264	237
Capitalized internal costs related to acquisition, exploration and development activities - subsidiaries	123	103	82
Area of land purchased		26
Production	768,000,000,000	657,000,000,000	565,000,000,000	500,000,000,000
Production volumes replaced with proved reserve additions, percentage	591.00%	550.00%				591.00%
Additions	1,693,000,000,000	3,285,000,000,000	920,000,000,000
Revisions		326,000,000,000
Period of time needed to calculate ceiling value of reserves	12 months	12 months	12 months
Performance [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Revisions			(336,000,000,000)
Decrease Natural Gas Price [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Revisions			(2,088,000,000,000)
Seismic Costs Fayetteville Shale Play [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Net unevaluated costs excluded from amortization	12
Undeveloped Properties Fayetteville Shale [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Net unevaluated costs excluded from amortization	34
Additions	573,000,000,000	1,530,000,000,000	32,000,000,000
Undeveloped Properties Marcellus Shale [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Net unevaluated costs excluded from amortization	138
Undeveloped Properties New Ventures - Excluding Canada [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Net unevaluated costs excluded from amortization	367
Exploration Program in Canada [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Net unevaluated costs excluded from amortization	76
Wells In Progress [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Net unevaluated costs excluded from amortization	267
Northeast Appalachia [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Net increase (decrease) in production	103,000,000,000	97,000,000,000	30,000,000,000			103,000,000,000
Additions		4,000,000,000
Northeast Appalachia [Member] | Higher Gas Prices [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Revisions	10,000,000,000	35,000,000,000
Northeast Appalachia [Member] | Performance [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Revisions	636,000,000,000	62,000,000,000	36,000,000,000
Northeast Appalachia [Member] | Lower Gas Prices [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Revisions			(9,000,000,000)
Southwest Appalachia [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Net increase (decrease) in production	3,000,000,000					3,000,000,000
Additions	2,304,000,000,000
Revisions	543,000,000,000
Fayetteville Shale [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Net increase (decrease) in production	8,000,000,000	1,000,000,000	49,000,000,000			8,000,000,000
Fayetteville Shale [Member] | Higher Gas Prices [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Revisions	38,000,000,000	191,000,000,000
Fayetteville Shale [Member] | Performance [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Revisions	(126,000,000,000)	16,000,000,000	(362,000,000,000)
Fayetteville Shale [Member] | Lower Gas Prices [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Revisions			(1,684,000,000,000)
East Texas and Arkoma Basin [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Net increase (decrease) in production	(3,000,000,000)	(7,000,000,000)	(14,000,000,000)			(3,000,000,000)
Developed Properties Fayetteville Shale [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Additions	283,000,000,000	557,000,000,000	383,000,000,000
Developed Properties Northeast Appalachia [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Additions	246,000,000,000	386,000,000,000	195,000,000,000
Developed Properties Brown Dense [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Additions	2,000,000,000	2,000,000,000
Undeveloped Properties Northeast Appalachia [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Additions	589,000,000,000	810,000,000,000	305,000,000,000
Ark-La-Tex [Member] | Higher Gas Prices [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Revisions	6,000,000,000	21,000,000,000
Ark-La-Tex [Member] | Performance [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Revisions	(21,000,000,000)		(10,000,000,000)
Ark-La-Tex [Member] | Lower Gas Prices [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Revisions			(59,000,000,000)
Undeveloped Properties, Various Locations [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Discount rate of natural gas and oil reserves	10.00%	10.00%	10.00%
Proved undeveloped reserves	181,000,000,000	662,000,000,000	355,000,000,000			181,000,000,000
Number of locations	60	268	198			60
Present value of proved reserves, discounted basis	(28)	(97)	(71)			(28)
New Ventures [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Net increase (decrease) in production		1,000,000,000
New Ventures [Member] | Performance [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Revisions		1,000,000,000
Developed Properties Ark-La-Tex [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Additions			3,000,000,000
Developed Properties New Ventures [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Additions			2,000,000,000
Overton Field in East Texas [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Proved developed and undeveloped reserves			(141,000,000,000)
Chesapeake Property Acquisition [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Net unevaluated costs excluded from amortization	$ 3,600
Area of land purchased	413,000					413,000
Natural Gas [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Proved developed and undeveloped reserves	9,809,000,000,000	6,974,000,000,000	4,017,000,000,000	5,887,000,000,000	5,887,000,000,000	9,809,000,000,000
Production	(765,000,000,000)	(655,000,000,000)	(564,000,000,000)
Additions	1,691,000,000,000	3,283,000,000,000	918,000,000,000
Revisions	542,000,000,000	325,000,000,000	(2,088,000,000,000)
Proved undeveloped reserves	4,134,000,000,000	2,737,000,000,000	821,000,000,000	2,633,000,000,000	2,633,000,000,000	4,134,000,000,000
Average market prices used in reserves	4.35	3.67	2.76
Oil [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Proved developed and undeveloped reserves	37,615	373	244	996	996	37,615
Production	(235)	(138)	(83)
Additions	250	229	154
Revisions	(14)	38	(44)
Proved undeveloped reserves	30,170	1	1	13	13	30,170
Average market prices used in reserves	91.48	93.42	91.21
NGL [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Full cost ceiling test, price	23.79	43.45
Proved developed and undeveloped reserves	118,699					118,699
Production	(231)	(50)
Additions	48
Revisions	66	50
Proved undeveloped reserves	80,067					80,067
Average market prices used in reserves	23.79	43.45
Natural Gas and Oil [Member] | Estimated [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Proved developed and undeveloped reserves	10,747,000,000,000	6,976,000,000,000	4,018,000,000,000	5,893,000,000,000	5,893,000,000,000	10,747,000,000,000
Synthetic Gas, Synthetic Oil or Nonrenewable Natural Resources [Member]
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Proved developed and undeveloped reserves	0					0