Leases (Lease Income Associated with Operating Leases) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Leases [Abstract]
Fixed payments	$ 17	$ 17	$ 33	$ 34
Variable payments	16	25	39	52
Total lease income under operating leases	$ 33	$ 42	$ 72	$ 86