Divestitures (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales Proceeds				$ 151	$ 312
Asset Retirement Obligations Associated with Assets Sold				29	77
Gain on Divestitures		$ 0	$ (30)	0	(72)
US Onshore Assets Sold [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales Proceeds			16	$ 151	126
Net Book Value of Assets Sold			0		(118)
Goodwill Allocated to Assets Sold			(1)		(7)
Asset Retirement Obligations Associated with Assets Sold			14		34
Other Closing Adjustments			1		2
Gain on Divestitures			$ 30		37
China [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales Proceeds	[1]				186
Net Book Value of Assets Sold					(149)
Other Closing Adjustments					(2)
Gain on Divestitures					$ 35

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