Segment and Geographic Area Reporting - Revenue and Long-lived Assets by Geography (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) service_offering	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | service_offering	1
Revenues	$ 7,038	$ 7,022	$ 9,066
Long-lived assets	996	1,131
United States
Segment Reporting Information [Line Items]
Revenues	3,982	4,186	5,429
Long-lived assets	638	692
Europe
Segment Reporting Information [Line Items]
Revenues	2,023	1,883	2,326
Long-lived assets	258	312
Canada
Segment Reporting Information [Line Items]
Revenues	398	393	518
Long-lived assets	68	84
Other areas
Segment Reporting Information [Line Items]
Revenues	635	560	$ 793
Long-lived assets	$ 32	$ 43