Leases - Lease Cost (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Leases [Abstract]
Operating lease cost	$ 61	$ 38	$ 123	$ 77
Finance lease cost
Amortization of right-of-use assets	30	1	89	2
Interest on lease liabilities	6	0	9	0
Lease, cost	97	39	221	79
Variable lease cost included within operating lease cost	8	$ 15	19	$ 28
Accelerated amortization expense included within finance lease expense	$ 7		$ 45