Natural Gas and Oil Property Divestitures - VPP Volumes Produced During Period Table (Details)	12 Months Ended
	Dec. 31, 2013 Mcfe	Dec. 31, 2012 Mcfe	Dec. 31, 2011 Mcfe
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Reserves (Energy) (Duration)	170,900,000,000	202,200,000,000	199,900,000,000
Natural Gas [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	154,000,000,000	178,400,000,000	189,200,000,000
Oil [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	864,300	1,580,800	1,161,500
NGL Reserves
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	1,964,700	2,372,700	615,400
VPP 10 Anadarko Basin Granite Wash [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Reserves (Energy) (Duration)	25,800,000,000	32,800,000,000	0
VPP 10 Anadarko Basin Granite Wash [Member] | Natural Gas [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	13,500,000,000	18,100,000,000	0
VPP 10 Anadarko Basin Granite Wash [Member] | Oil [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	547,000	727,000	0
VPP 10 Anadarko Basin Granite Wash [Member] | NGL Reserves
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	1,509,000	1,729,100	0
VPP 9 Mid-Continent [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Reserves (Energy) (Duration)	21,000,000,000	23,700,000,000	22,500,000,000
VPP 9 Mid-Continent [Member] | Natural Gas [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	17,000,000,000	18,400,000,000	17,300,000,000
VPP 9 Mid-Continent [Member] | Oil [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	213,200	249,300	250,500
VPP 9 Mid-Continent [Member] | NGL Reserves
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	455,700	643,600	615,400
VPP 8 Barnett Shale [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Reserves (Energy) (Duration)	68,100,000,000	79,700,000,000	101,200,000,000
VPP 8 Barnett Shale [Member] | Natural Gas [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	68,100,000,000	79,700,000,000	101,200,000,000
VPP 8 Barnett Shale [Member] | Oil [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	0	0	0
VPP 8 Barnett Shale [Member] | NGL Reserves
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	0	0	0
VPP 7 Permian Basin [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Reserves (Energy) (Duration)		3,400,000,000	5,000,000,000
VPP 7 Permian Basin [Member] | Natural Gas [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)		400,000,000	400,000,000
VPP 7 Permian Basin [Member] | Oil [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)		490,300	773,000
VPP 7 Permian Basin [Member] | NGL Reserves
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)		0	0
VPP 6 East Texas and Texas Gulf Coast [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Reserves (Energy) (Duration)	4,900,000,000	5,500,000,000	6,200,000,000
VPP 6 East Texas and Texas Gulf Coast [Member] | Natural Gas [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	4,800,000,000	5,300,000,000	6,000,000,000
VPP 6 East Texas and Texas Gulf Coast [Member] | Oil [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	24,000	24,000	27,000
VPP 6 East Texas and Texas Gulf Coast [Member] | NGL Reserves
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	0	0	0
VPP 5 South Texas [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Reserves (Energy) (Duration)	7,700,000,000	9,000,000,000	11,200,000,000
VPP 5 South Texas [Member] | Natural Gas [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	7,500,000,000	8,800,000,000	11,000,000,000
VPP 5 South Texas [Member] | Oil [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	25,400	27,400	35,900
VPP 5 South Texas [Member] | NGL Reserves
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	0	0	0
VPP 4 Anadarko and Arkoma Basins [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Reserves (Energy) (Duration)	10,500,000,000	12,200,000,000	14,300,000,000
VPP 4 Anadarko and Arkoma Basins [Member] | Natural Gas [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	10,200,000,000	11,700,000,000	13,800,000,000
VPP 4 Anadarko and Arkoma Basins [Member] | Oil [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	54,700	62,800	75,100
VPP 4 Anadarko and Arkoma Basins [Member] | NGL Reserves
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	0	0	0
VPP 3 Anadarko Basin [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Reserves (Energy) (Duration)	8,100,000,000	9,300,000,000	10,700,000,000
VPP 3 Anadarko Basin [Member] | Natural Gas [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	8,100,000,000	9,300,000,000	10,700,000,000
VPP 3 Anadarko Basin [Member] | Oil [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	0	0	0
VPP 3 Anadarko Basin [Member] | NGL Reserves
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	0	0	0
VPP 2 Texas, Oklahoma and Kansas [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Reserves (Energy) (Duration)	10,300,000,000	11,300,000,000	12,500,000,000
VPP 2 Texas, Oklahoma and Kansas [Member] | Natural Gas [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	10,300,000,000	11,400,000,000	12,500,000,000
VPP 2 Texas, Oklahoma and Kansas [Member] | Oil [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	0	0	0
VPP 2 Texas, Oklahoma and Kansas [Member] | NGL Reserves
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	0	0	0
VPP 1 Kentucky and West Virginia [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Reserves (Energy) (Duration)	14,500,000,000	15,300,000,000	16,300,000,000
VPP 1 Kentucky and West Virginia [Member] | Natural Gas [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	14,500,000,000	15,300,000,000	16,300,000,000
VPP 1 Kentucky and West Virginia [Member] | Oil [Member]
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	0	0	0
VPP 1 Kentucky and West Virginia [Member] | NGL Reserves
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Proved Developed and Undeveloped Reserves (Volume)	0	0	0