Debt - Interest Expense and Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Debt Disclosure [Abstract]
Interest expense	$ 59	$ 60	$ 158	$ 179
Interest income	$ 56	$ 62	$ 182	$ 193