Leases Narrative (Details) $ in Millions	Mar. 31, 2019 USD ($)
Operating Leased Assets [Line Items]
Operating Lease, Right-of-Use Asset	$ 797
Operating Lease, Liability, Current	195
Operating Lease, Liability, Noncurrent	$ 622
Minimum [Member]
Operating Leased Assets [Line Items]
Lessee, Operating Lease, Renewal Term	1 month
Maximum [Member]
Operating Leased Assets [Line Items]
Lessee, Operating Lease, Renewal Term	49 years