Debt, Description of short-term debt (Details) - USD ($) $ in Millions	1 Months Ended		6 Months Ended
	Apr. 30, 2020	Mar. 31, 2020	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Description of short-term debt [Line Items]
Weighted average interest rate, short-term debt (in hundredths)			1.30%		3.30%
Issuance of short-term debt			$ 521	$ 2,000
Outstanding short-term borrowings			659
Repayment of short-term debt			$ 500
U.S. Receivables Facility [Member]
Description of short-term debt [Line Items]
Expiration date			July 2021
Maximum borrowing capacity			$ 900
Additional borrowing capacity, uncommitted loans			300
Maximum allowed letters of credit			$ 200
Terms of debt covenants			We are required to maintain a leverage ratio at the end of every fiscal quarter of 3.50 to 1.00, or less, for the period covering the most recent four quarters.
Issuance of short-term debt		$ 500
Outstanding short-term borrowings			$ 0
Outstanding letters of credit			0
Unused availability			524
Repayment of short-term debt	$ 500
Commercial paper [Member]
Description of short-term debt [Line Items]
Maximum borrowing capacity			$ 2,500
Description of interest rate			Interest rates on the commercial paper outstanding at June 30, 2020 are based on the terms of the notes and range from 0.23% to 0.35%
Outstanding short-term borrowings			$ 473