Interest Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Financing agreements
Interest on borrowings(1)	$ 57	$ 57	$ 171	$ 171
Fees on financing agreements(1)	4	3	10	10
Interest on tax liabilities	3	(1)	3	0
Interest capitalized	(1)	0	(2)	(1)
Interest expense	$ 63	$ 59	$ 182	$ 180