Other Finance Income (Costs) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Other Nonoperating Income (Expense) [Abstract]
Pension interest cost	$ (0.7)	$ (0.7)	$ (1.4)	$ (1.5)
Expected return on pension plan assets	0.9	0.9	1.8	1.9
Foreign currency translation on senior bank debt	(3.2)		(0.3)
Foreign currency remeasurement on hedging instrument	2.1		0.2
Other finance income (costs)	$ (0.9)	$ 0.2	$ 0.3	$ 0.4