Retirement Plans - Components of Net Periodic Pension (Credit) Cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Settlement loss	$ 0.0	$ 0.8	$ 0.0	$ 0.8
United States
Defined Benefit Plan Disclosure [Line Items]
Interest cost	0.5	0.7	1.6	1.9
Expected return on plan assets	(0.8)	(0.9)	(2.4)	(2.5)
Amortization of net actuarial loss	0.1	0.1	0.3	0.3
Net periodic pension credit	(0.2)	(0.1)	(0.5)	(0.3)
Settlement loss	0.0	0.8	0.0	0.8
Total pension (credit) cost	$ (0.2)	$ 0.7	$ (0.5)	$ 0.5