Leases - Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Operating Leases
Operating Lease ROU Assets	$ 851	$ 855
Operating Lease Liabilities due Within One Year	198	199
Operating Lease Liabilities	684	668
Total Operating Lease Liabilities	882	867
Finance Leases
Property, Plant and Equipment, at cost	262	259
Accumulated Depreciation	(60)	(50)
Property, Plant and Equipment, net	202	209
Long Term Debt and Finance Leases due Within One Year	18	6
Long Term Debt and Finance Leases	232	243
Total Finance Lease Liabilities	$ 250	$ 249
Weighted Average Remaining Lease Term
Operating Leases	7 years 3 months 18 days	7 years 2 months 12 days
Finance Leases	30 years 10 months 24 days	31 years 7 months 6 days
Weighted Average Discount Rate
Operating Leases	6.85%	6.69%
Finance Leases	8.48%	8.46%