Suspended Wells-Exploratory Capitalized Well Costs (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	$ 852		$ 922	$ 793
2009-2011 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	461
2006-2008 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	260
2001-2005 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	131
Aktote-Kazakhstan [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	19	[1],[2]
Aktote-Kazakhstan [Member] | 2001-2005 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	19	[1],[2]
Alpine Satellite-Alaska [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	23	[1]
Alpine Satellite-Alaska [Member] | 2001-2005 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	23	[1]
Browse Basin-Australia[Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	216	[3]
Browse Basin-Australia[Member] | 2009-2011 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	216	[3]
Caldita/Barossa-Australia [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	78	[3]
Caldita/Barossa-Australia [Member] | 2006-2008 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	44	[3]
Caldita/Barossa-Australia [Member] | 2001-2005 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	34	[3]
Clair SW-UK [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	14	[3]
Clair SW-UK [Member] | 2009-2011 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	14	[3]
Fiord West-Alaska [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	16	[1]
Fiord West-Alaska [Member] | 2006-2008 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	16	[1]
Kairan-Kazakhstan [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	27	[1],[2]
Kairan-Kazakhstan [Member] | 2006-2008 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	14	[1],[2]
Kairan-Kazakhstan [Member] | 2001-2005 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	13	[1],[2]
Kalamkas-Kazakhstan Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	14	[1],[2]
Kalamkas-Kazakhstan Member] | 2009-2011 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	5	[1],[2]
Kalamkas-Kazakhstan Member] | 2006-2008 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	5	[1],[2]
Kalamkas-Kazakhstan Member] | 2001-2005 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	4	[1],[2]
Kashagan II-Kazakhstan [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	45	[1],[2]
Kashagan II-Kazakhstan [Member] | 2009-2011 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	9	[1],[2]
Kashagan II-Kazakhstan [Member] | 2006-2008 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	26	[1],[2]
Kashagan II-Kazakhstan [Member] | 2001-2005 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	10	[1],[2]
Muskwa-Canada [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	56	[3]
Muskwa-Canada [Member] | 2009-2011 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	56	[3]
NPR-A-Alaska [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	17	[1]
NPR-A-Alaska [Member] | 2009-2011 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	17	[1]
Pisagon-Malaysia [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	10	[1]
Pisagon-Malaysia [Member] | 2001-2005 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	10	[1]
Saleski-Canada [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	18	[3]
Saleski-Canada [Member] | 2006-2008 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	18	[3]
Shenandoah-Lower 48 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	43	[3]
Shenandoah-Lower 48 [Member] | 2009-2011 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	43	[3]
Sunrise 3-Australia[Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	13	[1]
Sunrise 3-Australia[Member] | 2006-2008 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	13	[1]
Surmont III and beyond-Canada [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	45	[3]
Surmont III and beyond-Canada [Member] | 2009-2011 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	21	[3]
Surmont III and beyond-Canada [Member] | 2006-2008 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	22	[3]
Surmont III and beyond-Canada [Member] | 2001-2005 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	2	[3]
Thornbury-Canada [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	21	[3]
Thornbury-Canada [Member] | 2006-2008 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	21	[3]
Tiber-Lower 48 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	40	[3]
Tiber-Lower 48 [Member] | 2009-2011 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	40	[3]
Titan-Norway [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	12	[1]
Titan-Norway [Member] | 2009-2011 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	12	[1]
Ubah-Malaysia [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	36	[1]
Ubah-Malaysia [Member] | 2009-2011 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	11	[1]
Ubah-Malaysia [Member] | 2006-2008 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	25	[1]
Uge-Nigeria [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	30	[1],[2]
Uge-Nigeria [Member] | 2006-2008 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	16	[1],[2]
Uge-Nigeria [Member] | 2001-2005 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	14	[1],[2]
Other of $10 million or less each [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	59	[1],[3]
Other of $10 million or less each [Member] | 2009-2011 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	17	[1],[3]
Other of $10 million or less each [Member] | 2006-2008 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	40	[1],[3]
Other of $10 million or less each [Member] | 2001-2005 [Member]
Aging of exploratory well costs that have been capitalized for more than one year
Aging of Exploratory Well Cost that have been capitalized for more than one year	$ 2	[1],[3]

[1] Appraisal drilling complete; costs being incurred to assess development.

[2] Assets held for sale as of December 31, 2012.

[3] Additional appraisal wells planned.