Leasing (Depreciation Expense on Operating Lease Assets) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Leases, Operating [Abstract]
Operating Lease, Lease Income	$ 343	$ 363	$ 710	$ 724
Depreciation expense on operating lease assets	241	262	491	523
Remarketing losses (gains), net	11	(23)	9	(38)
Net depreciation expense on operating lease assets	252	239	500	485
Variable lease payments, excessive wear and tear	$ 5	$ 5	$ 12	$ 9