v3.19.3.a.u2
Income Taxes (Narrative) (Details)
$ in Millions
12 Months Ended
Dec. 31, 2019
USD ($)
jurisdiction
Dec. 31, 2018
USD ($)
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Income Taxes [Line Items]        
Provisional amount for one-time transitional tax liability     $ 10,200  
Deferred tax benefit reflecting reduced U.S. tax rate     376  
Cumulative net tax benefit reversal $ 5,282 $ 4,177 14,531  
Net tax credit carryforwards 3,000      
Total unrecognized tax benefits 3,377 4,652 4,696 $ 5,393
Total unrecognized tax benefits that, if recognized, would affect our effective tax rate 2,300 2,900 $ 3,000  
Uncertain tax positions, accrued interest and penalties $ 130 $ 490    
Number of tax jurisdictions | jurisdiction 2      
Cost Sharing Arrangement, Income Tax Expense        
Income Taxes [Line Items]        
Cumulative net tax benefit reversal $ 418      
Federal        
Income Taxes [Line Items]        
Net operating loss carryforwards 1,800      
State        
Income Taxes [Line Items]        
Net operating loss carryforwards 3,100      
Foreign Tax Authority        
Income Taxes [Line Items]        
Net operating loss carryforwards $ 1,900