Leases - Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Jun. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Operating Leases
Operating Lease ROU Assets	$ 854	$ 882	$ 0
Operating Lease Liabilities due Within One Year	200	204	0
Operating Lease Liabilities	664	$ 684	0
Total Operating Lease Liabilities	864
Finance Leases
Property, Plant and Equipment, at cost	259
Accumulated Depreciation	(45)
Property, Plant and Equipment, net	214
Long Term Debt and Finance Leases due Within One Year	6
Long Term Debt and Finance Leases	242
Total Finance Lease Liabilities	$ 248		$ 37
Weighted Average Remaining Lease Term
Operating Leases	6 years 10 months 24 days
Finance Leases	32 years 2 months 12 days
Weighted Average Discount Rate
Operating Leases	6.72%
Finance Leases	8.48%