Summary of Significant Accounting Policies - Property and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 4,844	$ 4,166
Less: Accumulated depreciation	(2,683)	(2,208)
Total	2,161	1,958
Depreciation expense	566	555	$ 498
Land
Property, Plant and Equipment [Line Items]
Property and equipment, gross	48	47
Data processing equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 3,630	3,025
Data processing equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	3 years
Data processing equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Buildings and leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 801	724
Buildings and leasehold improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Buildings and leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	40 years
Furniture and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 365	$ 370
Furniture and equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Furniture and equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	8 years