Divestitures VPP Volume Remaining to Be Delivered Table (Details)	Sep. 30, 2013 Corporate VPP [Member] Reserve Volume Remaining Mcfe	Sep. 30, 2013 Corporate VPP [Member] Natural Gas [Member] Reserve Volume Remaining Mcf	Sep. 30, 2013 Corporate VPP [Member] Oil [Member] Reserve Volume Remaining MBbls	Sep. 30, 2013 Corporate VPP [Member] NGL Reserves Reserve Volume Remaining MBbls	Sep. 30, 2013 VPP 10 Anadarko Basin Granite Wash [Member] Reserve Volume Remaining Mcfe	Sep. 30, 2013 VPP 10 Anadarko Basin Granite Wash [Member] Natural Gas [Member] Reserve Volume Remaining Mcf	Sep. 30, 2013 VPP 10 Anadarko Basin Granite Wash [Member] Oil [Member] Reserve Volume Remaining MBbls	Sep. 30, 2013 VPP 10 Anadarko Basin Granite Wash [Member] NGL Reserves Reserve Volume Remaining MBbls	Sep. 30, 2013 VPP 9 Mid-Continent [Member] Reserve Volume Remaining Mcfe	May 31, 2011 VPP 9 Mid-Continent [Member] Natural Gas [Member] Mcf	Sep. 30, 2013 VPP 9 Mid-Continent [Member] Natural Gas [Member] Reserve Volume Remaining Mcf	May 31, 2011 VPP 9 Mid-Continent [Member] Oil [Member] MBbls	Sep. 30, 2013 VPP 9 Mid-Continent [Member] Oil [Member] Reserve Volume Remaining MBbls	May 31, 2011 VPP 9 Mid-Continent [Member] NGL Reserves MBbls	Sep. 30, 2013 VPP 9 Mid-Continent [Member] NGL Reserves Reserve Volume Remaining MBbls	Sep. 30, 2013 VPP 8 Barnett Shale [Member] Reserve Volume Remaining Mcfe	Sep. 30, 2010 VPP 8 Barnett Shale [Member] Natural Gas [Member] Mcf	Sep. 30, 2013 VPP 8 Barnett Shale [Member] Natural Gas [Member] Reserve Volume Remaining Mcf	Sep. 30, 2010 VPP 8 Barnett Shale [Member] Oil [Member] MBbls	Sep. 30, 2013 VPP 8 Barnett Shale [Member] Oil [Member] Reserve Volume Remaining MBbls	Sep. 30, 2010 VPP 8 Barnett Shale [Member] NGL Reserves MBbls	Sep. 30, 2013 VPP 8 Barnett Shale [Member] NGL Reserves Reserve Volume Remaining MBbls	Sep. 30, 2013 VPP 6 East Texas and Texas Gulf Coast [Member] Reserve Volume Remaining Mcfe	Feb. 28, 2010 VPP 6 East Texas and Texas Gulf Coast [Member] Natural Gas [Member] Mcf	Sep. 30, 2013 VPP 6 East Texas and Texas Gulf Coast [Member] Natural Gas [Member] Reserve Volume Remaining Mcf	Feb. 28, 2010 VPP 6 East Texas and Texas Gulf Coast [Member] Oil [Member] MBbls	Sep. 30, 2013 VPP 6 East Texas and Texas Gulf Coast [Member] Oil [Member] Reserve Volume Remaining MBbls	Feb. 28, 2010 VPP 6 East Texas and Texas Gulf Coast [Member] NGL Reserves MBbls	Sep. 30, 2013 VPP 6 East Texas and Texas Gulf Coast [Member] NGL Reserves Reserve Volume Remaining MBbls	Sep. 30, 2013 VPP 5 South Texas [Member] Reserve Volume Remaining Mcfe	Aug. 31, 2009 VPP 5 South Texas [Member] Natural Gas [Member] Mcf	Sep. 30, 2013 VPP 5 South Texas [Member] Natural Gas [Member] Reserve Volume Remaining Mcf	Aug. 31, 2009 VPP 5 South Texas [Member] Oil [Member] MBbls	Sep. 30, 2013 VPP 5 South Texas [Member] Oil [Member] Reserve Volume Remaining MBbls	Aug. 31, 2009 VPP 5 South Texas [Member] NGL Reserves MBbls	Sep. 30, 2013 VPP 5 South Texas [Member] NGL Reserves Reserve Volume Remaining MBbls	Sep. 30, 2013 VPP 4 Anadarko and Arkoma Basins [Member] Reserve Volume Remaining Mcfe	Dec. 31, 2008 VPP 4 Anadarko and Arkoma Basins [Member] Natural Gas [Member] Mcf	Sep. 30, 2013 VPP 4 Anadarko and Arkoma Basins [Member] Natural Gas [Member] Reserve Volume Remaining Mcf	Dec. 31, 2008 VPP 4 Anadarko and Arkoma Basins [Member] Oil [Member] MBbls	Sep. 30, 2013 VPP 4 Anadarko and Arkoma Basins [Member] Oil [Member] Reserve Volume Remaining MBbls	Dec. 31, 2008 VPP 4 Anadarko and Arkoma Basins [Member] NGL Reserves MBbls	Sep. 30, 2013 VPP 4 Anadarko and Arkoma Basins [Member] NGL Reserves Reserve Volume Remaining MBbls	Sep. 30, 2013 VPP 3 Anadarko Basin [Member] Reserve Volume Remaining Mcfe	Aug. 31, 2008 VPP 3 Anadarko Basin [Member] Natural Gas [Member] Mcf	Sep. 30, 2013 VPP 3 Anadarko Basin [Member] Natural Gas [Member] Reserve Volume Remaining Mcf	Aug. 31, 2008 VPP 3 Anadarko Basin [Member] Oil [Member] MBbls	Sep. 30, 2013 VPP 3 Anadarko Basin [Member] Oil [Member] Reserve Volume Remaining MBbls	Aug. 31, 2008 VPP 3 Anadarko Basin [Member] NGL Reserves MBbls	Sep. 30, 2013 VPP 3 Anadarko Basin [Member] NGL Reserves Reserve Volume Remaining MBbls	Sep. 30, 2013 VPP 2 Texas, Oklahoma and Kansas [Member] Reserve Volume Remaining Mcfe	May 31, 2008 VPP 2 Texas, Oklahoma and Kansas [Member] Natural Gas [Member] Mcf	Sep. 30, 2013 VPP 2 Texas, Oklahoma and Kansas [Member] Natural Gas [Member] Reserve Volume Remaining Mcf	May 31, 2008 VPP 2 Texas, Oklahoma and Kansas [Member] Oil [Member] MBbls	Sep. 30, 2013 VPP 2 Texas, Oklahoma and Kansas [Member] Oil [Member] Reserve Volume Remaining MBbls	May 31, 2008 VPP 2 Texas, Oklahoma and Kansas [Member] NGL Reserves MBbls	Sep. 30, 2013 VPP 2 Texas, Oklahoma and Kansas [Member] NGL Reserves Reserve Volume Remaining MBbls	Sep. 30, 2013 VPP 1 Kentucky and West Virginia [Member] Reserve Volume Remaining Mcfe	Dec. 31, 2007 VPP 1 Kentucky and West Virginia [Member] Natural Gas [Member] Mcf	Sep. 30, 2013 VPP 1 Kentucky and West Virginia [Member] Natural Gas [Member] Reserve Volume Remaining Mcf	Dec. 31, 2007 VPP 1 Kentucky and West Virginia [Member] Oil [Member] MBbls	Sep. 30, 2013 VPP 1 Kentucky and West Virginia [Member] Oil [Member] Reserve Volume Remaining MBbls	Dec. 31, 2007 VPP 1 Kentucky and West Virginia [Member] NGL Reserves MBbls	Sep. 30, 2013 VPP 1 Kentucky and West Virginia [Member] NGL Reserves Reserve Volume Remaining MBbls
Acquisitions, Divestitures, Joint Ventures, VPP's [Line Items]
Contract Term					101 months				89 months							23 months							76 months							40 months							39 months							70 months							67 months							111 months
Proved Developed Reserves (Volume)		492,200,000,000	3,300,000	9,400,000		57,100,000,000	1,800,000	6,300,000		138,000,000,000	89,500,000,000	1,700,000	1,100,000	4,800,000	3,100,000		390,000,000,000	112,000,000,000	0	0	0	0		44,000,000,000	22,600,000,000	300,000	200,000	0	0		67,000,000,000	18,700,000,000	200,000	100,000	0	0		95,000,000,000	27,200,000,000	500,000	100,000	0	0		93,000,000,000	33,000,000,000	0	0	0	0		94,000,000,000	23,100,000,000	0	0	0	0		208,000,000,000	109,000,000,000	0	0	0	0
Proved Developed Reserves (Energy)	568,300,000,000				106,100,000,000				114,400,000,000							112,000,000,000							23,600,000,000							19,000,000,000							28,100,000,000							33,000,000,000							23,100,000,000							109,000,000,000

Net quantities of an enterprise's interests in proved developed reserves of either crude oil (including condensate and natural gas liquids), natural gas, synthetic oil and gas, or other nonrenewable natural resource that is intended to be upgraded into synthetic oil and gas as of the beginning and the end of the year. "Net" quantities of reserves include those relating to the enterprise's operating and nonoperating interests in properties. Quantities of reserves relating to royalty interests owned are included in "net" quantities if the necessary information is available to the enterprise. "Net" quantities does not include reserves relating to interests of others in properties owned by the enterprise. The unit of measure for reserve quantities is defined as "barrels" for oil and synthetic oil reserves or "cubic feet" or "cubic meters" for natural gas and synthetic gas reserves.

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