Property and Equipment, Net (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	$ 1,357	$ 1,206
Less: accumulated depreciation and amortization	(1,010)	(928)
Total property and equipment, net	347	278
Office and Computer Equipment
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	$ 300	260
Office and Computer Equipment | Minimum
Property, Plant and Equipment [Line Items]
Property plant and equipment useful life	3 years
Office and Computer Equipment | Maximum
Property, Plant and Equipment [Line Items]
Property plant and equipment useful life	10 years
Office Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	$ 52	49
Office Furniture and Fixtures | Minimum
Property, Plant and Equipment [Line Items]
Property plant and equipment useful life	3 years
Office Furniture and Fixtures | Maximum
Property, Plant and Equipment [Line Items]
Property plant and equipment useful life	10 years
Internal-use Computer Software
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	$ 771	666
Internal-use Computer Software | Minimum
Property, Plant and Equipment [Line Items]
Property plant and equipment useful life	1 year
Internal-use Computer Software | Maximum
Property, Plant and Equipment [Line Items]
Property plant and equipment useful life	10 years
Leasehold Improvements and Building
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	$ 234	$ 231
Leasehold Improvements and Building | Minimum
Property, Plant and Equipment [Line Items]
Property plant and equipment useful life	1 year
Leasehold Improvements and Building | Maximum
Property, Plant and Equipment [Line Items]
Property plant and equipment useful life	20 years