Income Taxes - Uncertain tax positions (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Movement in uncertain tax positions
Uncertain tax positions at the beginning of the period	$ 0.1	$ 3.5	$ 3.4
Gross increase - tax position in prior periods			0.2
Gross decrease - tax position in prior periods		(3.4)	(0.1)
Gross increase - current period tax position
Settlements
Lapse in statute of limitations
Foreign exchange
Uncertain tax positions at the end of the period	0.1	$ 0.1	$ 3.5
Interest and penalties included within uncertain tax positions	0.0
Impact of uncertain tax positions on effective tax rate, if recognized	$ 0.1

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

No definition available.

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- Definition

Amount of unrecognized tax benefits.

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Amount of decrease in unrecognized tax benefits resulting from foreign currency translation.

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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Amount of expense for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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