Retirement Benefit Plans (Schedule of defined benefit plan obligations and assets) (Details) - Retirement Plans - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Benefit obligation	$ (587.1)	$ (551.7)	$ (475.6)
Fair value of plan assets	585.0	524.5	$ 430.2
Funded status	(2.1)	(27.2)
Amounts recognized in the Consolidated Balance Sheets:
Other assets	30.4	2.5
Accrued compensation and benefits	$ (32.5)	$ (29.7)

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Amount of asset, recognized in statement of financial position, for overfunded defined benefit pension and other postretirement plans.

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Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

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Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status.

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Amount of liability, recognized in statement of financial position, for defined benefit pension and other postretirement plans.

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