Current Receivables - Narrative (Details) - USD ($)
$ in Millions
Dec. 31, 2019
Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total current receivables, gross $ 6,739 $ 6,296
Less: Allowance for doubtful accounts (323) (327)
Total current receivables, net 6,416 5,969
Customer receivables    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total current receivables, gross 5,448 4,974
Related parties    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total current receivables, gross 495 653
Other    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Total current receivables, gross $ 796 $ 669