Income Taxes - Valuation Allowances and Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2018	Sep. 30, 2018	Dec. 31, 2017
Income Taxes
Amount of valuation allowance reversed	$ 3.5	$ 5.0
Valuation allowance			$ 5.0
Unrecognized tax benefits	2.1	2.1	2.1
Unrecognized tax benefits that would impact effective tax rate	$ 0.0	0.0	0.0
Unrecognized tax benefits, period increase (decrease)		$ 0.0	$ 0.0

Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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- References

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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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-SubTopic 10
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Amount of increase (decrease) in unrecognized tax benefits attributable to uncertain tax positions taken in tax returns.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

+ References

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Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset.

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