Restructuring Restructuring (Details) $ in Millions	3 Months Ended
Restructuring Restructuring (Details) $ in Millions	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Restructuring Cost and Reserve [Line Items]
Severance Costs	$ 10.7
Restructuring Reserve	3.8
2018 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	$ 5.0
Employees affected	350
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	$ 0.9
Employees affected	345
Facility Charge [Domain]
Restructuring Cost and Reserve [Line Items]
Severance Costs	$ 5.7
Restructuring Reserve	1.8
CEO Transition [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	7.3
2017 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs		$ 12.8
Employees affected		315
Restructuring Reserve	$ 3.3		$ 5.8
buw Acquisition [Member] [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs		$ 0.9
Other Restructuring [Member] \| 2017 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs		$ 2.2
Employees affected		150

CONVERGYS CORP 10-Q