Income Taxes, Interest Expense (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest expense [Abstract]
Interest included as component of income tax expense	$ 1.1	$ 0.0	$ 0.1
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	2.8	1.7
Unrecognized Tax Benefits, Income Tax Penalties Expense	$ 0.0	$ 0.0	$ 0.0

No definition available.

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- Definition

Amount of expense for penalties related to a tax position claimed or expected to be claimed in the tax return.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32718-109319

+ Details

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- Definition

Amount of interest expense accrued for an underpayment of income taxes.

+ References

+ Details

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- Definition

Amount of interest expense for an underpayment of income taxes.

+ References

+ Details

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