Retirement Benefit Plans - Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Amortization of net losses expected in next year	$ 14.1
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	0.1	$ 0.1	$ 0.2
Interest cost	2.9	3.2	4.0
Amortization of unrecognized prior service (credit) cost	(4.1)	(4.1)	(4.9)
Amortization of unrecognized loss	1.2	1.3	2.1
Net periodic benefit cost	0.1	0.5	1.4
Amortization of net losses expected in next year	0.6
Amortization of net prior service cost expected in the next year	3.6
Domestic Plan [Member] | Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost	8.5	8.9	9.6
Expected return on plan assets	(13.6)	(13.2)	(15.0)
Settlements, curtailments and other	0.0	0.0
Amortization of unrecognized prior service (credit) cost	(0.8)	(0.8)	(0.8)
Amortization of unrecognized loss	4.2	4.2	5.1
Net periodic benefit cost	(1.7)	(0.9)	(1.1)
Foreign Plan [Member] | Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	17.9	18.0	16.2
Interest cost	12.0	11.0	12.5
Expected return on plan assets	(27.0)	(23.8)	(24.3)
Settlements, curtailments and other	0.3	0.3
Amortization of unrecognized prior service (credit) cost	0.1	0.0	0.6
Amortization of unrecognized loss	6.9	7.9	6.2
Net periodic benefit cost	$ 10.2	$ 13.4	$ 11.2