Financing Arrangements - Notes Payable (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Short-term Debt [Line Items]
Total notes payable	$ 2,157	$ 1,034
Commercial paper
Short-term Debt [Line Items]
Total notes payable	947	0
Short-term borrowings to banks
Short-term Debt [Line Items]
Total notes payable	$ 1,210	$ 1,034