Leases Lease-related Assets and Weighted Average Life and Discount Rate (Details) $ in Millions	Mar. 31, 2019 USD ($)
Lease-related Assets [Abstract]
Operating Lease, Right-of-Use Asset	$ 244
Operating Lease, Liability	$ 252
Operating Lease, Weighted Average Remaining Lease Term	9 years 4 months 24 days
Finance Lease, Weighted Average Remaining Lease Term	1 year 1 month 7 days
Operating Lease, Weighted Average Discount Rate, Percent	3.20%
Finance Lease, Weighted Average Discount Rate, Percent	13.10%