Leases - Lease Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating and short-term lease cost	$ 67	$ 43
Lease, Cost [Abstract]
Amortization of right-of-use assets	5	9
Interest on lease liability	0	1
Total finance lease cost	5	10
Total lease cost	$ 72	$ 53