v3.10.0.1
Tax Matters - Narrative (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Income Tax Contingency [Line Items]      
Unrecognized tax benefits excluding associated interest $ 5,100 $ 5,400  
Deferred tax assets associated with unrecognized tax benefits 1,100 1,200  
Unrecognized tax benefits, interest on income taxes expense 103 208 $ 72
Unrecognized accrued interest decrease as a result of cash payments 16 4  
Unrecognized tax benefits, interest on income taxes accrued 1,100 975  
Decrease in unrecognized tax benefits is reasonably possible, amount of unrecorded benefit 75    
Unremitted earnings of international subsidiaries 31,000    
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 128 118  
Income Taxes Payable [Member]      
Income Tax Contingency [Line Items]      
Unrecognized tax benefits, interest on income taxes accrued 6    
Other Taxes Payable [Member]      
Income Tax Contingency [Line Items]      
Unrecognized tax benefits, interest on income taxes accrued $ 1,100 $ 975