Divestitures (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales Proceeds				$ 151	$ 146
Asset Retirement Obligations Associated with Assets Sold				15	43
Gain on Divestitures		$ (1)	$ (44)	0	(42)
US Onshore Assets Sold [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales Proceeds				$ 151	110
Net Book Value of Assets Sold					(118)
Goodwill Allocated to Assets Sold					(6)
Asset Retirement Obligations Associated with Assets Sold					20
Gain on Divestitures					6
CHINA
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Other Significant Noncash Transaction, Value of Consideration Given					150
Sales Proceeds	[1]				186
Net Book Value of Assets Sold					149
Other Closing Adjustments					2
Gain on Divestitures					$ (35)

[1] Includes $150 million cash received on July 2, 2014, which was recorded as accounts receivable at June 30, 2014.