Retirement Benefit Plans - Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
U.S. other postretirement benefit plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 0.1	$ 0.2	$ 0.2
Interest cost	3.2	4.0	5.7
Amortization of unrecognized prior service (credit) cost	(4.1)	(4.9)	(5.7)
Amortization of unrecognized loss	1.3	2.1	3.1
Net periodic benefit cost	0.5	1.4	3.3
Amortization of net (losses) expected in next year	(1.2)
Amortization of net prior service cost expected in the next year	4.1
Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Amortization of net (losses) expected in next year	11.2
United States | Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost	8.9	9.6	11.2
Expected return on plan assets	(13.2)	(15.0)	(17.0)
Settlements, curtailments and other	0.0	0.0	25.7
Amortization of unrecognized prior service (credit) cost	(0.8)	(0.8)	(0.8)
Amortization of unrecognized loss	4.2	5.1	6.3
Net periodic benefit cost	(0.9)	(1.1)	25.4
Non-US [Member] | Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	18.0	16.2	14.9
Interest cost	11.0	12.5	14.1
Expected return on plan assets	(23.8)	(24.3)	(24.8)
Settlements, curtailments and other	0.3	0.0	(0.8)
Amortization of unrecognized prior service (credit) cost	0.0	0.6	0.1
Amortization of unrecognized loss	7.9	6.2	6.6
Net periodic benefit cost	$ 13.4	$ 11.2	$ 10.1