Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	$ 0.1	$ 0.1	$ 0
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at Beginning of Year	6.8us-gaap_UnrecognizedTaxBenefits	6.4us-gaap_UnrecognizedTaxBenefits	6.2us-gaap_UnrecognizedTaxBenefits
Additions for Tax Positions of Prior Years	0.3	0.3	0.2
Balance at End of Year	7.2us-gaap_UnrecognizedTaxBenefits	6.8us-gaap_UnrecognizedTaxBenefits	6.4us-gaap_UnrecognizedTaxBenefits
Possible decrease in unrecognized tax benefit	3.5
Unrecognized tax benefit	3.4	3.4	3.5
Accrued interest included in unrecognized tax benefits	3.8	3.4	2.9
Interest on income taxes expense	$ (0.4)	$ (0.4)	$ (0.4)

Unrecognized Tax Benefit that Would Not Impact Effective Tax Rate, Tax Position with Uncertain Timing of Deductibility

No definition available.

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

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Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Unrecognized Tax Benefit

-URI http://asc.fasb.org/extlink&oid=6527854

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

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Amount of interest expense for an underpayment of income taxes.

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