Leases - Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Jun. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Operating leases:
Operating lease right-of-use assets	$ 20,865	$ 20,987	$ 0
Current portion of operating lease liabilities	1,793	1,803	0
Long-term operating lease liabilities	18,849	$ 18,832	$ 0
Total operating lease liabilities	20,642
Finance leases:
Property and equipment, net	531
Current portion of long-term debt	26
Long-term debt	559
Total finance lease liabilities	$ 585
Weighted average remaining lease term
Operating leases	14 years
Finance leases	20 years 3 months 18 days
Weighted average discount rate
Operating leases	4.70%
Finance leases	7.40%