Leases - Lease Position (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Assets
Operating lease assets	$ 5,627	$ 5,994
Finance lease assets	1,062	490
Total lease assets	6,689	6,484
Liabilities
Current operating lease liabilities	801	955
Current finance lease liabilities	233	109
Noncurrent operating lease liabilities	5,294	5,801
Noncurrent finance lease liabilities	821	294
Total lease liabilities	$ 7,149	$ 7,159
Operating leases, weighted-average remaining lease term	12 years	12 years
Finance leases, Operating leases, weighted-average remaining lease term	5 years	7 years
Operating leases, weighted-average discount rate	3.73%	3.69%
Finance leases, weighted-average discount rate	3.46%	5.23%