Debt - Interest Expense and Income (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Debt Disclosure [Abstract]
Interest expense	[1]	$ 60	$ 61	$ 178	$ 184
Interest income	[2]	$ 62	$ 70	$ 193	$ 216

[1] Includes Cost of financing as well as non-financing interest expense that is included in Other expenses, net in the Condensed Consolidated Statements of Income.

[2] Includes Financing revenue as well as other interest income that is included in Other expenses, net in the Condensed Consolidated Statements of Income.