Leases - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Lessee, Lease, Description [Line Items]
Option to extend lease period	30 years
Option to terminate lease period	1 year
Percentage of leased real estate of total lease obligation	75.00%
Operating lease expense under ASC Topic 840		$ 380	$ 309
Gross amounts of capital lease assets under ASC 840 Topic		485
Accumulated depreciation of assets recorded as capital leases under ASC 840 Topic	$ 5,286	4,994
Additional leases that have not yet commenced	$ 116
Assets Held under Capital Leases
Lessee, Lease, Description [Line Items]
Accumulated depreciation of assets recorded as capital leases under ASC 840 Topic		$ 61
Minimum
Lessee, Lease, Description [Line Items]
Term of leases that have not yet commenced	1 year
Maximum
Lessee, Lease, Description [Line Items]
Term of leases that have not yet commenced	20 years