Property and Equipment, net - Schedule of Property and Equipment Net (Detail) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 2,328	$ 2,280
Less: Accumulated depreciation and amortization	(1,631)	(1,561)
Property and equipment, net	697	719
Land
Property, Plant and Equipment [Line Items]
Property and equipment, gross	61	61
Buildings and leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	616	574
Capitalized software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	981	957
Furniture, fixtures & equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	484	440
Projects in process
Property, Plant and Equipment [Line Items]
Property and equipment, gross	92	154
Buses and support vehicles
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 94	$ 94