Income Taxes - Schedule of unrecognized tax benefits (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning of year	$ 23.5	$ 26.3	$ 21.1
Increases from prior period tax positions	5.4	1.3	7.6
Decreases from prior period tax positions	(0.8)	(3.0)	(0.7)
Increases from current period tax positions	4.7	0.2	4.4
Decreases relating to settlements with taxing authorities	(5.9)	(1.3)	(6.1)
End of year	$ 26.9	$ 23.5	$ 26.3

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.

+ References

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

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