Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2010		Sep. 30, 2010		Jun. 30, 2010		Mar. 31, 2010		Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Components of income (loss) before income taxes [Abstract]
Domestic																	$ (537)		$ 235		$ (808)
Foreign																	1,252		796		544
Income (Loss) Before Income Taxes	(470)	[1]	722	[1]	425	[1]	37	[1]	69	[2]	298	[2]	320	[2]	343	[2]	715	[1]	1,031	[2]	(264)
Current Taxes [Abstract]
Federal																	11		25		45
State																	2		2		1
Foreign																	330		208		117
Total Current																	343		235		163
Deferred Taxes [Abstract]
Federal																	(130)		86		(320)
State																	(3)		1		(5)
Foreign																	52		(16)		29
Total Deferred																	(81)		71		(296)
Total Income Tax Provision (Benefit)																	262		306		(133)
Effective Tax Rate (in hundredths)																	36.60%		29.70%		50.40%
Federal statutory tax rate reconciliation [Abstract]
Federal Statutory Rate (in hundredths)																	35.00%		35.00%		35.00%
Effect of
Earnings of Equity Method Investees (in hundredths)																	(9.30%)		(4.00%)		11.30%
State Taxes, Net of Federal Benefit (in hundredths)																	(0.10%)		0.30%		1.50%
Difference Between US and Foreign Rates (in hundredths)																	2.10%		1.70%		(1.40%)
Percentage Depletion in Excess of Basis (in hundredths)																	(0.60%)		(1.60%)		4.50%
Change in Valuation Allowance (in hundredths)																	4.60%		(2.20%)		1.50%
Oil Profits Tax - Israel (in hundredths)																	2.50%		0.00%		0.00%
Statutory Rate Change - UK (in hundredths)																	4.80%		0.00%		0.00%
Other, Net (in hundredths)																	(2.40%)		0.50%		(2.00%)
Effective Rate (in hundredths)																	36.60%		29.70%		50.40%
Deferred Tax Assets [Abstract]
Loss Carryforwards	66								72								66		72
Ecuador Investment	0								12								0		12
Accrued Expenses	11								10								11		10
Allowance for Doubtful Accounts	0								5								0		5
Net Pension Obligation	42								35								42		35
Postretirement Benefits	36								35								36		35
Deferred Compensation	86								94								86		94
Foreign Tax Credits	57								25								57		25
Commodity Derivative Assets	37								38								37		38
Other	39								32								39		32
Total Deferred Tax Assets	374								358								374		358
Valuation Allowance - Foreign Loss Carryforwards	(65)								(58)								(65)		(58)
Valuation Allowance - Foreign Tax Credits	(57)								0								(57)		0
Valuation Allowance - Ecuador Investment	0								(12)								0		(12)
Net Deferred Tax Assets	252								288								252		288
Deferred Tax Liabilities [Abstract]
Property, Plant and Equipment, Principally Due to Differences in Depreciation, Amortization, Lease Impairment and Abandonments	(2,276)								(2,389)								(2,276)		(2,389)
Total Deferred Tax Liability	(2,276)								(2,389)								(2,276)		(2,389)
Net Deferred Tax Liability	(2,024)								(2,101)								(2,024)		(2,101)
Deferred Tax Asset and Liability Classification [Abstract]
Deferred Income Tax Asset - Current	41								9								41		9
Deferred Income Tax Liability - Current	(6)								0								(6)		0
Deferred Income Tax Liability - Noncurrent	(2,059)								(2,110)								(2,059)		(2,110)
Net Deferred Tax Liability	(2,024)								(2,101)								(2,024)		(2,101)
Deferred Tax Assets [Abstract]
Total tax effect of foreign loss carryforwards	65								70								65		70		47
Valuation allowance amount on deferred tax asset related to foreign tax credits, increase (decrease)																	57		(28)
Percentage point change in 2011 consolidated effective tax rate due to changes in Israeli Oil Profits Taxation Law (in hundredths)																	4.00%
UK supplementary charge levied on oil and gas income prior to March 2011 increase (in hundredths)																	20.00%
UK supplementary charge levied on oil and gas income following March 2011 increase (in hundredths)																	32.00%
UK oil and gas income tax rate prior to March 2011 (in hundredths)																	50.00%
UK oil and gas income tax rate after March 2011 (in hundredths)																	62.00%
Increase in consolidated effective income tax rate due to changes in tax laws in the UK (in hundredths)																	7.00%
Increase in UK deferred tax liability due to change in UK tax law																	34
Increase in UK income tax expense due to change in UK tax law																	34
Accumulated undistributed earnings of foreign subsidiaries	2,000																2,000
Estimated future US taxes on the eventual remittance of accumulated undistributed foreign subsidiary earnings	329																329
Repatriated Accumulated Earnings of Foreign Subsidiaries																					180
Increase in US Income Tax Expense Due to Repatriation in 2009 and 2008																					13
Increase in US Income Tax Expense Due to Repatriation Recorded in 2008																					$ 9
US [Member]
Years Remaining Open to Examination [Abstract]
Earliest years remaining open to examinations																	2008
Equatorial Guinea [Member]
Years Remaining Open to Examination [Abstract]
Earliest years remaining open to examinations																	2007
Israel [Member]
Years Remaining Open to Examination [Abstract]
Earliest years remaining open to examinations																	2008
UK [Member]
Years Remaining Open to Examination [Abstract]
Earliest years remaining open to examinations																	2007
Netherlands [Member]
Years Remaining Open to Examination [Abstract]
Earliest years remaining open to examinations																	2009
China [Member]
Years Remaining Open to Examination [Abstract]
Earliest years remaining open to examinations																	2006

[1] First quarter 2011 included the following: $8 million asset impairment charges (See Note 4. Asset Impairments); and $286 million loss on commodity derivative instruments, including unrealized mark-to-market loss of $303 million (See Note 10. Derivative Instruments and Hedging Activities). Second quarter 2011 included the following: $143 million gain on commodity derivative instruments, including unrealized mark-to-market gain of $142 million (See Note 10. Derivative Instruments and Hedging Activities); $25 million pre-tax gain on divestitures due to the completed transfer of assets and exit from Ecuador (See Note 3. Acquisitions and Divestitures); and $131 million asset impairment charges (See Note 4. Asset Impairments). Third quarter 2011 included the following: $322 million gain on commodity derivative instruments, including unrealized mark-to-market gain of $300 million (See Note 10. Derivative Instruments and Hedging Activities). Fourth quarter 2011 included the following: $620 million asset impairment charges (See Note 4. Asset Impairments); and $137 million loss on commodity derivative instruments, including unrealized mark-to-market loss of $162 million (See Note 10. Derivative Instruments and Hedging Activities).

[2] First quarter 2010 included the following: $145 million gain on commodity derivative instruments, including unrealized mark-to-market gain of $147 million (See Note 10. Derivative Instruments and Hedging Activities). Second quarter 2010 included the following: $96 million gain on commodity derivative instruments, including unrealized mark-to-market gain of $63 million (See Note 10. Derivative Instruments and Hedging Activities); and $26 million rig contract termination expense due to the Deepwater Moratorium. Third quarter 2010 included the following: $38 million gain on commodity derivative instruments, including unrealized mark-to-market gain of $5 million (See Note 10. Derivative Instruments and Hedging Activities); $114 million gain on sale of non-core onshore US assets (See Note 3. Acquisitions and Divestitures); and $100 million asset impairment charges (See Note 4. Asset Impairments). Fourth quarter 2010 included the following: $122 million loss on commodity derivative instruments, including unrealized mark-to-market loss of $145 million (See Note 10. Derivative Instruments and Hedging Activities); and $44 million asset impairment charges (See Note 4. Asset Impairments).