Retirement Benefit Plans - Changes in Fair Value (Details) - Pension Plan [Member] - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Net Asset Value [Domain]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of plan assets at end of year	$ 794.9	$ 702.9
Foreign Plan [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of plan assets at end of year	274.7	254.6
Foreign Plan [Member] | Net Asset Value [Domain]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of plan assets at end of year	$ 231.8	$ 217.8