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Schedule of Changes in Unrecognized Income Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2015
Income Tax Uncertainties [Abstract]
Unrecognized tax benefits classified within deferred taxes as a reduction of net operating loss carryforwards				$ 12.1	$ 11.7
Reconciliation Of Unrecognized Tax Benefits Excluding Amounts Pertaining To Examined Tax Returns Roll Forward
Increases in prior period tax positions	$ 0.0	$ 0.0	$ 7.9
Decreases in prior period tax positions	(0.1)	(0.7)	(0.1)
Increases in current period tax positions	0.7	0.7	0.6
Unrecognized tax benefits	14.7	14.7	22.7	14.7	14.7	$ 19.6
Expiration of the statute of limitations	(0.6)	(0.4)	(1.1)
Settlements	0.0	(7.6)	(4.2)
Ending balance	$ 14.7	$ 14.7	$ 22.7
Income tax penalties and interest accrued				2.7	$ 3.2
Unrecognized tax benefits that would impact effective tax rate				3.0
Unrecognized tax benefits that will be recognized within 12 months of year end				$ 1.0

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Unrecognized Tax Benefits, Reduction of Operating Loss Carryforwards

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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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The amount of the unrecognized tax benefit of a position taken for which it is reasonably possible that the total amount thereof will significantly increase or decrease within twelve months of the balance sheet date.

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Amount of unrecognized tax benefits.

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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 accrued 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 decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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