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	$ 6,814	$ 6,389
Less: Allowance for doubtful accounts	(323)	(327)
Total current receivables, net	6,491	6,062
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	570	746
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total current receivables, gross	$ 796	$ 669