Share Plans - Schedule of Share-based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 4.2	$ 5.3	$ 10.4	$ 10.7
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	3.1	2.9	6.3	5.7
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	0.6	1.1	1.6	2.5
Performance share units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 0.5	$ 1.3	$ 2.5	$ 2.5