| **Income Taxes (Tables)**                            | 9 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
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| **Income Tax Disclosure [Abstract]**                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
| Schedule of Effective Income Tax Rate Reconciliation | The reconciliation of income taxes for the three and nine month periods ended September 30, 2014 and 2013, computed at the U.S. federal statutory income tax rate, compared to our effective income tax rate for continuing operations, was as follows:  Three Months Ended September 30, Nine Months Ended September 30,(in millions of dollars)2014 2013 2014 2013Income tax expense computed at U.S. statutory income tax rate (35%)$18.8 $14.4 $27.3 $11.8Decrease of valuation allowances, net— — — (7.0)Miscellaneous0.6 0.2 2.8 1.8Income tax expense as reported$19.4 $14.6 $30.1 $6.6Effective tax rate36.2% 35.6% 38.7% 19.6% |

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| - Definition
Tabular disclosure of the reconciliation using percentage or dollar amounts of the reported amount of income tax expense attributable to continuing operations for the year to the amount of income tax expense that would result from applying domestic federal statutory tax rates to pretax income from continuing operations.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32687-109319
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