Exit activities - Restructuring and Related Costs (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2020
Restructuring Cost and Reserve [Line Items]
Total	$ 9.1	$ 42.1
Special Charges
Restructuring Cost and Reserve [Line Items]
Inventory and asset write-offs	3.1	13.1
Special Charges \| One-time Termination Benefits
Restructuring Cost and Reserve [Line Items]
Severance costs and other	1.3	8.3
Cost of Sales \| Facility Closing
Restructuring Cost and Reserve [Line Items]
Accelerated depreciation	$ 4.7	$ 20.7

Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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Amount, after cash payment, of expenses associated with exit or disposal activities pursuant to an authorized plan and expenses resulting from the write-down of assets. Excludes expenses related to a business combination, a discontinued operation or an asset retirement obligation.

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