Leases - Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Dec. 31, 2019	Jan. 01, 2019
Operating leases:
Operating lease right-of-use assets	$ 20,860	$ 20,987
Current portion of operating lease liabilities	1,596	1,803
Long-term operating lease liabilities	18,926	$ 18,832
Total operating lease liabilities	20,522
Finance leases:
Property and equipment, gross	790
Accumulated depreciation	(38)
Property and equipment, net	752
Current portion of long-term debt	27
Long-term debt	781
Total finance lease liabilities	$ 808
Weighted average remaining lease term (in years)
Operating leases	13 years 9 months 18 days
Finance leases	20 years 6 months
Weighted average discount rate
Operating leases	4.60%
Finance leases	6.70%