Retirement Benefit Plans - Change in Benefit Obligation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in benefit obligation:
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 35.4	$ 11.3	$ 11.5
Pension Plan [Member]
Change in benefit obligation:
Defined Benefit Plan, Plan Assets, Contributions by Employer	35.4	11.3
Defined Benefit Plan, Benefit Obligation, Business Combination	0.0	49.7
UNITED STATES | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax	4.8	6.4	8.1
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), before Tax	0.0	0.0
Defined Benefit Plan, Plan Assets, Amount	520.2	448.3	531.9
Change in benefit obligation:
Benefit obligation at beginning of year	586.6	643.0
Service cost	10.7	12.6	12.2
Interest cost	23.5	24.0	24.6
Amendments	0.0	0.0
Actuarial losses (gains)	74.9	(36.7)
Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss)	0.0	0.0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment	0.0	10.2	1.1
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment		(10.2)
Defined Benefit Plan, Plan Assets, Benefits Paid	61.0	95.8
Benefit obligation at end of year	634.7	586.6	643.0
Company contributions / payments	104.2	(37.5)
Defined Benefit Plan, Plan Assets, Contributions by Employer	28.7	5.3
Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss)	0.0	0.0
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(114.5)	(138.3)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), after Reclassification Adjustment, before Tax	(1.6)	(1.7)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax	0.0	0.0
Foreign Plan [Member]
Change in benefit obligation:
Defined Benefit Plan, Benefit Obligation, Business Combination	0.4	2.0
Foreign Plan [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax	3.9	4.0	0.5
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), before Tax	0.0	3.6
Defined Benefit Plan, Plan Assets, Amount	274.7	254.6	292.4
Change in benefit obligation:
Benefit obligation at beginning of year	300.3	335.2
Service cost	1.5	1.7	1.6
Interest cost	7.3	7.2	7.5
Amendments	0.0	3.6
Actuarial losses (gains)	29.1	(7.4)
Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss)	7.6	(17.2)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment	0.0	0.0	0.0
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment	0.0	0.0
Defined Benefit Plan, Plan Assets, Benefits Paid	17.4	24.8
Benefit obligation at end of year	328.8	300.3	$ 335.2
Company contributions / payments	21.9	(5.1)
Defined Benefit Plan, Plan Assets, Contributions by Employer	6.7	6.0
Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss)	8.9	(15.4)
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(54.1)	(45.7)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), after Reclassification Adjustment, before Tax	(0.2)	(0.1)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax	$ 0.1	$ 0.0