v3.19.3.a.u2
Income And Other Taxes (Narrative) (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Income And Other Taxes [Abstract]      
Reconciliation between income tax expense and theoretical U.S. tax rate, statutory rate 21.00% 21.00% 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 $ 0 $ 3 $ 36
Interest payable on income tax reserves 71 169  
Valuation Allowance [Abstract]      
Valuation allowance change from 2018 to 2019 98    
Asset valuation allowances 1,924 1,826  
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)
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 (740) $ (289) $ (5,920)
Change in net provisions [Member]      
Valuation Allowance [Abstract]      
Valuation allowance change from 2018 to 2019 113    
Effects of foreign currency translation [Member]      
Valuation Allowance [Abstract]      
Valuation allowance change from 2018 to 2019 $ (15)