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 leases	6 years
Rent expense under prior lease accounting rules (ASC 840)		$ 260	$ 284
Amount of operating lease contracts not yet commenced	$ 45
Term of operating lease contracts not yet commenced	15 years
Minimum
Lessee, Lease, Description [Line Items]
Remaining term of leases	1 year
Maximum
Lessee, Lease, Description [Line Items]
Remaining term of leases	10 years