Share Plans - Schedule of Share-based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 4.2	$ 4.8	$ 20.8	$ 15.2
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	2.4	3.0	9.4	9.3
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	0.7	0.6	2.5	2.2
Performance share units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 1.1	$ 1.2	$ 8.9	$ 3.7