Dispositions Dispositions - Discontinued Ops (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Mar. 31, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Sale of Oil and Gas Property and Equipment			$ 105	$ 2,237
NORWAY
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Revenue	$ 528			1,901
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, before Income Tax	487			1,617
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, Net of Tax	$ 127			449	[1]
ANGOLA
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Interest Percentage		10.00%
Proceeds from Sale of Oil and Gas Property and Equipment		$ 2,000
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax		$ 576
Disposal Group, Including Discontinued Operation, Revenue				58
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, before Income Tax				51
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax				470
Discontinued Operations, Income (Loss) from Discontinued Operations During Phase-out Period Plus Gain (Loss) from Disposal, Net of Tax				$ 609

[1] Includes a tax benefit of $26 million related to a decrease in the valuation allowance on U.S. foreign tax credits from the Norway operations.