Revenue - Disaggregated Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 1,051	$ 1,158
Point in time
Disaggregation of Revenue [Line Items]
Revenue	30	39
Over time
Disaggregation of Revenue [Line Items]
Revenue	1,021	1,119
Commercial Industries
Disaggregation of Revenue [Line Items]
Revenue	572	612
Commercial Industries | Customer Experience Management
Disaggregation of Revenue [Line Items]
Revenue	168	171
Commercial Industries | Business Operations Solutions
Disaggregation of Revenue [Line Items]
Revenue	153	166
Commercial Industries | Commercial Healthcare Solutions
Disaggregation of Revenue [Line Items]
Revenue	113	122
Commercial Industries | Human Resource Services
Disaggregation of Revenue [Line Items]
Revenue	138	153
Government services
Disaggregation of Revenue [Line Items]
Revenue	290	325
Government services | Government Healthcare Solutions
Disaggregation of Revenue [Line Items]
Revenue	152	177
Government services | Government Services Solutions
Disaggregation of Revenue [Line Items]
Revenue	138	148
Transportation Services
Disaggregation of Revenue [Line Items]
Revenue	189	184
Transportation Services | Roadway Charging & Management Services
Disaggregation of Revenue [Line Items]
Revenue	78	79
Transportation Services | Transit Solutions
Disaggregation of Revenue [Line Items]
Revenue	67	54
Transportation Services | Curbside Management Solutions
Disaggregation of Revenue [Line Items]
Revenue	22	27
Transportation Services | Public Safety Solutions
Disaggregation of Revenue [Line Items]
Revenue	20	21
Transportation Services | Commercial Vehicles
Disaggregation of Revenue [Line Items]
Revenue	2	3
Other
Disaggregation of Revenue [Line Items]
Revenue	0	37
Other | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Disaggregation of Revenue [Line Items]
Revenue	0	36
Other | Education
Disaggregation of Revenue [Line Items]
Revenue	$ 0	$ 1