Provision (Benefit) for Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended					1 Months Ended			3 Months Ended
	Sep. 30, 2011	Dec. 31, 2010	Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010	Sep. 30, 2012	Aug. 31, 2011 Internal Revenue Service (IRS) [Member]	Jul. 31, 2011 Internal Revenue Service (IRS) [Member]	Dec. 31, 2012 Internal Revenue Service (IRS) [Member]	Mar. 31, 2012 Foreign Tax Authority [Member]
Current :
Federal			$ 91		$ 181	$ (21)
State			17		13	(2)
Foreign			40		(6)	29
Total			148		188	6
Deferred:
Federal			220		(61)	144
State			(13)		(14)	(48)
Foreign			5		11	12
Total			212		(64)	108
Provision (benefit) for income taxes			360		124	114
Provision (benefit) for income taxes from continuing operations at federal statutory rate:
Provision (benefit) at statutory rate			451		421	135
Increases (decreases) in taxes resulting from:
Impact of nontaxable noncontrolling interests			(72)		(96)	(58)
State income taxes (net of federal benefit)			2		11	(35)
Foreign operations - net			(36)		(14)	(22)
Federal settlements			0		(109)	0
International revised assessments			0		(38)	0
Deferred taxes on undistributed earnings of certain foreign operations	(66)	66	0		(66)	66
Reduction of tax benefits on Medicare Part D federal subsidy			0		0	11
Other - net			15		15	17
Provision (benefit) for income taxes			360		124	114
Deferred tax liabilities:
Property, plant, and equipment			72		65
Investments			3,146		2,560
Other			34		46
Total deferred tax liabilities			3,252		2,671
Deferred tax assets:
Accrued liabilities			313		324
Minimum tax credits			74	[1]	119
State loss and credit carryovers			195		170
Other			90		98
Total deferred tax assets			672		711
Less valuation allowance			144		145
Net deferred tax assets			528		566
Overall net deferred tax liabilities			2,724		2,105
Reconciliation of beginning and ending amount of unrecognized tax benefits
Balance at beginning of period			38		91
Additions based on tax positions related to the current year			4		26
Additions for tax positions of prior years			22		4
Reductions for tax positions of prior years			(6)		(39)
Settlement with taxing authorities			0		(44)
Balance at end of period		91	58		38	91
Income Tax Contingency [Line Items]
Reductions in state income taxes (net of federal benefit) due to a reduction in our estimate of the effective deferred state rate						43
Foreign income (loss) in Income from continuing operations before income taxes			196		173	144
Adjustment to deferred tax asset for AMT allocable to WPX			15
Deferred taxes on undistributed earnings of certain foreign operations that are no longer considered permanently invested	(66)	66	0		(66)	66
Undistributed earnings from foreign subsidiaries considered to be permanently reinvested			630
Cash payments for income taxes (net of refunds and including discontinued operations)			198		296	40
Unrecognized tax benefits		91	58		38	91
Reduction of income tax expense, net of federal tax expense, if recognized			62
Total interest and penalties recognized as part of income tax expense (benefit)			(7)		(56)	11
Total interest and penalties accrued as uncertain tax positions			7		15
Tax benefit from finalized settlements			0		109	0
Tax benefit from international revised assessments			0		38	0
Cash payments (refunds) related to the settlements/revised assessments								77	82		(21)
Tax provision (benefit) from income tax examination							2
Cash payment (refund) from income tax examination										12
Tax settlements with WPX			$ 2

[1] In conjunction with the 2011 spin-off of WPX, alternative minimum tax credits were allocated between us and WPX. In 2012, adjustments of $15 million were made to this component of the deferred tax asset for the 2009 to 2010 Internal Revenue Service (IRS) audit adjustments and finalization of the 2011 income tax return, reducing the alternative minimum tax credit allocated to WPX.