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Income And Other Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income And Other Taxes [Abstract]
Reconciliation between income tax expense and theoretical U.S. tax rate, statutory rate	21.00%	35.00%	35.00%
Potential percentage decrease in unrecognized tax benefits	10.00%
Potential percentage increase in unrecognized tax benefits	10.00%
Interest expense on income tax reserves	$ 3	$ 36	$ 4
Interest payable on income tax reserves	169	168
Valuation Allowance [Abstract]
Valuation allowance change from 2017 to 2018	(739)
Asset valuation allowances	1,826	2,565
US Tax Reform [Member]
Income And Other Taxes [Abstract]
Net deferred income tax expense (credits)/charges for tax rate and law changes	(291)	(5,942)
Valuation Allowance [Abstract]
Valuation allowance change from 2017 to 2018	(234)
Changes in Non U.S. tax laws and rates
Income And Other Taxes [Abstract]
Net deferred income tax expense (credits)/charges for tax rate and law changes		22
Total US and Non US
Income And Other Taxes [Abstract]
Net deferred income tax expense (credits)/charges for tax rate and law changes	(289)	$ (5,920)	$ 180
Increase Reduction In Deferred Tax Assets [Member] \| U.S. [Member]
Valuation Allowance [Abstract]
Valuation allowance change from 2017 to 2018	$ (333)