Restructuring - Rollforward of all restructuring accrual (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Rollforward of all restructuring accrual
Balance at beginning of period	$ 3.1	$ 4.4	$ 3.1	$ 5.6
Restructuring expense	1.1	1.0	8.3	11.0
Use of reserve	(1.9)	(2.0)	(9.1)	(12.7)
Reserve reclassification				(0.3)
Currency translation	(0.1)		(0.1)	(0.2)
Balance at end of period	$ 2.2	$ 3.4	$ 2.2	$ 3.4

Amount of cash payments made as the result of exit or disposal activities. Excludes payments associated with a discontinued operation or an asset retirement obligation.

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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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Carrying amount (including both current and noncurrent portions of the accrual) as of the balance sheet date pertaining to a specified type of cost associated with exit from or disposal of business activities or restructuring pursuant to a duly authorized plan.

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Amount of expense (reversal of expense) which increases (decreases) the restructuring reserve from an adjustment to a previously accrued restructuring liability.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of foreign currency translation gain (loss) which decreases (increases) the restructuring reserve.

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