Accumulated Other Comprehensive Loss - OCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated other comprehensive loss
Other comprehensive income, net of tax
Pre-tax amount	$ (73.8)	$ 42.1	$ 68.8
Tax expense (benefit)	1.3	0.2	0.3
Accumulated Translation Adjustment [Member]
Other comprehensive income, net of tax
Pre-tax amount	(48.2)	73.1	74.3
Tax impact	1.3	0.3	0.4
Net amount	(46.9)	73.4	74.7
Retirement benefit asset, net
Other comprehensive income, net of tax
Pre-tax amount	(23.5)	(29.0)	(4.1)
Tax impact		(0.1)	(0.1)
Net amount	(23.5)	(29.1)	(4.2)
Reclassification to net income
Other comprehensive income, net of tax
Pre-tax amount	(2.1)	(2.0)	(1.4)
Net amount	$ (2.1)	$ (2.0)	$ (1.4)