Leases - Components of Lease Cost (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Finance lease cost
Amortization of right-of-use assets	$ 60	$ 42
Interest	3	2
Operating lease cost	340	246
Variable lease cost and other, net	60	49
Total lease cost	$ 463	$ 339
Weighted-average remaining lease term
Operating leases	12 years 9 months 18 days	13 years 1 month 6 days
Finance leases	15 years 2 months 12 days	15 years 1 month 6 days
Weighted-average discount rate
Operating leases	3.20%	3.60%
Finance leases	3.10%	3.20%