Income Taxes (Rollforward of Uncertain Tax Positions) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Uncertain Tax Positions [Rollforward]
Beginning balance	$ 9.4	$ 8.1	$ 0.0
Additions based on tax positions related to the current year	3.7	2.7	3.2
Additions for tax positions of prior years	0.7	0.0	4.9
Reductions for tax positions of prior years	(0.3)	(1.4)	0.0
Ending balance	$ 13.5	$ 9.4	$ 8.1

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
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-Section 50
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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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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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- Definition

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

+ References

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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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