Other Financial Data - Components of Fixed Assets, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Fixed Assets, net [Line Items]
Fixed assets, gross	$ 1,949	$ 1,847
Less: Accumulated depreciation	1,391	1,318
Fixed assets, net	558	529
Depreciation of fixed assets	151	179	$ 167
Software
Fixed Assets, net [Line Items]
Fixed assets, gross	861	797
Leasehold improvements
Fixed Assets, net [Line Items]
Fixed assets, gross	409	425
Computer equipment
Fixed Assets, net [Line Items]
Fixed assets, gross	269	268
Furniture, fixtures and equipment
Fixed Assets, net [Line Items]
Fixed assets, gross	267	279
Construction in progress
Fixed Assets, net [Line Items]
Fixed assets, gross	109	45
Other
Fixed Assets, net [Line Items]
Fixed assets, gross	$ 34	$ 33