Retirement Benefit Plans - Narrative (Details) - USD ($)	3 Months Ended			12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Periodic Benefit (Cost) Credit	$ (21,100,000)	$ (16,900,000)	$ (19,700,000)	$ 4,100,000	$ (12,800,000)	$ (18,100,000)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment			(10,200,000)
Retirement Benefit Plans (Textual) [Abstract]
Return on plan assets				$ 27,900,000	23,700,000	21,800,000
Company common stock	1,582,428			1,582,428
Fair value of company common stock	$ 89,100,000			$ 89,100,000
Defined Benefit Plan, Plan Assets, Contributions by Employer				35,400,000	11,300,000	11,500,000
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Periodic Benefit (Cost) Credit				(13,900,000)	(38,800,000)	23,200,000
Retirement Benefit Plans (Textual) [Abstract]
Current liabilities	6,900,000		28,900,000	6,900,000	28,900,000
Projected benefit obligation	244,100,000			244,100,000
Accumulated benefit obligations	237,000,000.0			237,000,000.0
Fair value of plan assets	80,700,000			80,700,000
Pension accumulated benefit obligation	$ 942,000,000.0		$ 864,900,000	$ 942,000,000.0	864,900,000
Percentage Increase in Value of Pension Assets Due to Investment Performance				18.70%
Expected amortization of prior service cost				$ 1,700,000
Defined Benefit Plan, Plan Assets, Contributions by Employer				35,400,000	11,300,000
Employee Stock [Member]
Retirement Benefit Plans (Textual) [Abstract]
Dividends				2,300,000	2,900,000	3,000,000.0
UNITED STATES | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Periodic Benefit (Cost) Credit				$ 3,500,000	$ (30,000,000.0)	$ (23,100,000)
Discount rate	3.50%		4.36%	3.50%	4.36%	3.80%	4.34%
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment				$ 0	$ 10,200,000	$ 1,100,000
Percentage of Defined Benefit Plan Obligation in US				66.00%
Defined Benefit Plan, Benefit Obligation	$ 634,700,000		$ 586,600,000	$ 634,700,000	586,600,000	$ 643,000,000.0
Retirement Benefit Plans (Textual) [Abstract]
Discount rate				4.36%
Expected long-term return on plan assets				6.12%
Defined benefit pension plan percentage of fair value of plan assets				65.00%
Current liabilities	$ 5,400,000		$ 27,400,000	$ 5,400,000	27,400,000
Defined Benefit Plan, Plan Assets, Contributions by Employer				$ 28,700,000	$ 5,300,000
UNITED STATES | Forecast [Member] | Pension Plan [Member]
Retirement Benefit Plans (Textual) [Abstract]
Discount rate				3.50%
Expected long-term return on plan assets				5.22%
UNITED STATES | Maximum [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.55%		4.43%	3.55%	4.43%
Retirement Benefit Plans (Textual) [Abstract]
Discount rate				4.43%	3.94%	4.50%
Expected long-term return on plan assets				6250000.00%	6.50%	6.50%
UNITED STATES | Minimum [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.04%		4.05%	3.04%	4.05%
Retirement Benefit Plans (Textual) [Abstract]
Discount rate				3.67%	3.75%	4.34%
Expected long-term return on plan assets				5350000.00%	5.75%	5.75%
Foreign Plan [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Periodic Benefit (Cost) Credit				$ (17,400,000)	$ (8,800,000)	$ (100,000)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment				0	0	0
Defined Benefit Plan, Benefit Obligation	$ 328,800,000		$ 300,300,000	328,800,000	300,300,000	$ 335,200,000
Retirement Benefit Plans (Textual) [Abstract]
Current liabilities	$ 1,500,000		$ 1,500,000	1,500,000	1,500,000
Defined Benefit Plan, Plan Assets, Contributions by Employer				$ 6,700,000	$ 6,000,000.0
Foreign Plan [Member] | Maximum [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	9.00%		11.00%	9.00%	11.00%
Retirement Benefit Plans (Textual) [Abstract]
Discount rate				11.00%	9.00%	9.00%
Expected long-term return on plan assets				9.00%	9.00%	9.25%
Foreign Plan [Member] | Minimum [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	0.75%		1.50%	0.75%	1.50%
Retirement Benefit Plans (Textual) [Abstract]
Discount rate				1.50%	1.25%	1.25%
Expected long-term return on plan assets				2.50%	2.50%	0.75%
Discount Rate In Dollars [Domain] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Periodic Benefit (Cost) Credit				$ 100,900,000	$ 83,400,000	$ 52,900,000
Other Valuation Assumptions [Domain] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Periodic Benefit (Cost) Credit				3,100,000	62,400,000	8,700,000
Return on Plan Assets vs. Expectation [Domain] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Periodic Benefit (Cost) Credit				90,100,000	17,800,000	38,400,000
Discount Rate In Basis Points [Domain] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Periodic Benefit (Cost) Credit				86	56	$ 54
Overfunded Plan [Member] | Pension Plan [Member]
Retirement Benefit Plans (Textual) [Abstract]
Accumulated benefit obligations	$ 3,400,000		$ 6,200,000	$ 3,400,000	$ 6,200,000