Leasing Leasing (Lessor, Operating Lease, Payments to be Received, Maturity) (Details) $ in Millions	Mar. 31, 2019 USD ($)
Operating Leases, Future Minimum Payments Receivable [Abstract]
Operating lease, future minimum payments receivable, current	$ 1,024
Operating leases, future minimum payments receivable, in two years	933
Operating leases, future minimum payments receivable, in three years	402
Operating leases, future minimum payments receivable, in four years	57
Operating leases, future minimum payments receivable, in five years	5
Operating leases, future minimum payments receivable, thereafter	0
Total lease payments from operating leases	$ 2,421