| **Fair Value Of Financial Instruments** | 6 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
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| **Fair Value Disclosures [Abstract]**   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| Fair Value Of Financial Instruments     | 13. Fair Value of Financial InstrumentsIn establishing a fair value, there is a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The basis of the fair value measurement is categorized in three levels, in order of priority, as described below:Level 1Unadjusted quoted prices in active markets for identical assets or liabilitiesLevel 2Unadjusted quoted prices in active markets for similar assets or liabilities, or Unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active, or Inputs other than quoted prices that are observable for the asset or liabilityLevel 3Unobservable inputs for the asset or liabilityWe utilize the best available information in measuring fair value. Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement.We have determined that our financial assets and liabilities are Level 2 in the fair value hierarchy. The following table sets forth our financial assets and liabilities that were accounted for at fair value on a recurring basis as of June 30, 2016 and December 31, 2015:(in millions of dollars)June 30, 2016 December 31, 2015Assets:   Forward currency contracts$1.3 $2.6Liabilities:   Forward currency contracts$2.3 $0.4Our forward currency contracts are included in "Other current assets" or "Other current liabilities" and mature within 12 months. The forward foreign currency exchange contracts are primarily valued based on the foreign currency spot and forward rates quoted by the banks or foreign currency dealers. As such, these derivative instruments are classified within Level 2.The fair values of cash and cash equivalents, notes payable to banks, accounts receivable and accounts payable approximate carrying amounts due principally to their short maturities. The carrying amount of total debt was $883.6 million and $729.0 million and the estimated fair value of total debt was $909.8 million and $740.3 million at June 30, 2016 and December 31, 2015, respectively. The fair values are determined from quoted market prices, where available, and from investment bankers using current interest rates considering credit ratings and the remaining time to maturity. |

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The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.
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