Debt - Interest Expense and Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Debt Disclosure [Abstract]
Interest expense	$ 48	$ 59	$ 99	$ 119
Interest income	$ 59	$ 64	$ 126	$ 131