Property and Equipment - Schedule of Property and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Right-of-use lease assets	$ 278	$ 339
Total property and equipment	3,632	3,464
Less accumulated depreciation and amortization	(1,933)	(1,751)
Property and equipment, net	$ 1,699	1,713
Minimum
Property, Plant and Equipment [Line Items]
Right-of-use lease assets, useful life	1 year
Maximum
Property, Plant and Equipment [Line Items]
Right-of-use lease assets, useful life	20 years
Software and internally developed software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,407	1,223
Software and internally developed software | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	3 years
Software and internally developed software | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	7 years
Computer and network equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 792	803
Computer and network equipment | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	3 years
Computer and network equipment | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	5 years
Land
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 156	146
Buildings and building improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 342	322
Buildings and building improvements | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	15 years
Buildings and building improvements | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	40 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 322	314
Leasehold improvements | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	4 years
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	15 years
Equipment, aircraft and office furniture
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 335	$ 317
Equipment, aircraft and office furniture | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	4 years
Equipment, aircraft and office furniture | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	12 years