Property and Equipment, net - Schedule of Property and Equipment Net (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 2,097	$ 2,122
Less: Accumulated depreciation and amortization	(1,560)	(1,465)
Property and equipment, net	537	657
Land
Property, Plant and Equipment [Line Items]
Property and equipment, gross	50	49
Buildings and leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	525	592
Capitalized software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	932	918
Furniture, fixtures & equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	426	417
Projects in process
Property, Plant and Equipment [Line Items]
Property and equipment, gross	84	60
Buses and support vehicles
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 80	$ 86