Lessee - Components of Lease Expense (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 expense	$ 28	$ 33	$ 56	$ 66
Short-term lease expense	5	5	10	10
Variable lease expense	10	12	22	25
Sublease income	(1)	(1)	(1)	(1)
Total Lease expense	$ 42	$ 49	$ 87	$ 100