Leases - Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Operating leases:
Operating lease right-of-use assets	$ 20,757	$ 20,987	$ 0
Current portion of operating lease liabilities	1,798	1,803	0
Long-term operating lease liabilities	18,826	$ 18,832	$ 0
Total operating lease liabilities	20,624
Finance leases:
Property and equipment, net	560
Current portion of long-term debt	27
Long-term debt	591
Total finance lease liabilities	$ 618
Weighted average remaining lease term
Operating leases	13 years 9 months 18 days
Finance leases	20 years 7 months 6 days
Weighted average discount rate
Operating leases	4.60%
Finance leases	7.30%