Divestitures (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales Proceeds	$ 92	$ 76
Asset Retirement Obligations Associated with Assets Sold	14	10
Loss on Divestitures	(1)	15
Discontinued Operation, Income (Loss) from Discontinued Operation Disclosures [Abstract]
Discontinued Operations, Net of Tax	0	29
North Sea Assets Sold [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales Proceeds		38
Discontinued Operation, Income (Loss) from Discontinued Operation Disclosures [Abstract]
Oil and Gas Sales		10
Income Before Income Taxes		(1)
Income Tax Expense		7
Operating Income (Loss), Net of Tax		(8)
Gain on Sale, Net of Tax		37
Discontinued Operations, Net of Tax		29
US Onshore Assets Sold [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales Proceeds	92
Net Book Value of Assets Sold	(106)
Goodwill Allocated to Assets Sold	(6)
Asset Retirement Obligations Associated with Assets Sold	20
Other Closing Adjustments	(1)
Loss on Divestitures	$ (1)