v3.19.3.a.u2
Tax Matters - Narrative (Details) - USD ($)
$ in Millions
 3 Months Ended 12 Months Ended
Jun. 30, 2019
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Income Tax Contingency [Line Items]        
Unremitted earnings of international subsidiaries   $ 29,000    
Unrecognized tax benefits excluding associated interest   4,200 $ 5,100  
Deferred tax assets associated with unrecognized tax benefits   1,200 1,100  
Unrecognized tax benefits, interest on income taxes expense   564 (103) $ (208)
Unrecognized tax benefits, interest on income taxes accrued   485 1,100  
Unrecognized accrued interest decrease as a result of cash payments   13 16  
Effective Income Tax Rate Reconciliation, Tax Settlement, Amount $ (1,400)      
Decrease in unrecognized tax benefits is reasonably possible, amount of unrecorded benefit   200    
Noncurrent Deferred Tax Assets And Other Noncurrent Tax Assets [Member]        
Income Tax Contingency [Line Items]        
Deferred tax assets associated with unrecognized tax benefits   1,000 1,000  
Deferred Tax Liabilities, Net, Noncurrent [Member]        
Income Tax Contingency [Line Items]        
Deferred tax assets associated with unrecognized tax benefits   109 128  
Income Taxes Payable [Member]        
Income Tax Contingency [Line Items]        
Unrecognized tax benefits, interest on income taxes accrued   20 6  
Other Taxes Payable [Member]        
Income Tax Contingency [Line Items]        
Unrecognized tax benefits, interest on income taxes accrued   $ 465 $ 1,100