Income Taxes - Reconciliation of Beginning and Ending Amount of Gross Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of beginning and ending amount of gross unrecognized tax benefits
Balance at January 1,	$ 27.6	$ 27.5	$ 7.5
Additions based on tax positions of prior years	0.0	0.0	20.4
Change to prior tax positions due to tax rate changes	0.0	0.0	(0.4)
Additions based on tax positions of current year	0.0	0.1	0.0
Reduction due to settlements with tax authorities	(27.6)	0.0	0.0
Balance at December 31,	$ 0.0	$ 27.6	$ 27.5

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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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

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

+ References

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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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