| **Income Taxes (Tables)**            | 3 Months Ended                                                                                                                                                                                                                                                                                               |
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| **Income Tax Disclosure [Abstract]** |                                                                                                                                                                                                                                                                                                         |
| Summary of Income Tax Contingencies  | A reconciliation of the beginning and ending liability for unrecognized tax benefits is as follows (in millions): Gross Unrecognized Income Tax BenefitsBalance at December 31, 2014$0.9Gross amount of increases in unrecognized tax benefits related to prior periods1.5Balance at March 31, 2015$2.4 |

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| - Definition
Tabular disclosure of tax positions taken in the tax returns filed or to be filed for which it is more likely than not that the tax position will not be sustained upon examination by taxing authorities (i.e., uncertain tax positions) and other types of income tax contingencies, including: (1) the policy on classification of interest and penalties; (2) a tabular reconciliation of the total amounts of unrecognized tax benefits at the beginning and end of the period; the total amount(s) of: (3) unrecognized tax benefits that, if recognized, would affect the effective tax rate, and (4) interest and penalties recognized in each of the income statement and balance sheet; (5) for positions for which it is reasonably possible that the total amounts unrecognized will significantly change within 12 months of the reporting date the: (i) nature of the uncertainty, (ii) nature of the event that could occur that would cause the change, and (iii) an estimate of the range of the reasonably possible change or a statement that an estimate of the range cannot be made; and (6) a description of tax years that remain subject to examination by major tax jurisdictions.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32718-109319
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