Pensions - Schedule of Net Periodic Pension Expense (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Pension settlement charges		$ 6.1	$ 0.0	$ 0.0
U.S. Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost		0.0	0.0	0.0
Interest cost		7.6	7.8	7.6
Expected return on plan assets		(9.6)	(10.3)	(10.3)
Amortization of actuarial loss		2.5	5.6	6.8
Pension settlement charges	$ 6.1	6.1	0.0	0.0
Total Company-sponsored plans		6.6	3.1	4.1
Multi-employer plans		0.2	0.1	0.2
Net periodic pension expense		6.8	3.2	4.3
Non-U.S. Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost		0.2	0.2	0.2
Interest cost		1.4	1.8	2.1
Expected return on plan assets		(2.1)	(2.4)	(2.7)
Amortization of actuarial loss		0.6	0.6	0.7
Pension settlement charges		0.0	0.0	0.0
Total Company-sponsored plans		0.1	0.2	0.3
Multi-employer plans		0.0	0.0	0.0
Net periodic pension expense		$ 0.1	$ 0.2	$ 0.3