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Financial Instruments and Risk Management (Unrealized Gains (Losses) on Foreign Currency Contracts) (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016
Disclosure of detailed information about hedged items [line items] |  |
Unrealized gains | $ 0.3 | $ (1.6)
Foreign Currency [Member] |  |
Disclosure of detailed information about hedged items [line items] |  |
Unrealized gains | 13.3 | 2.3
Foreign Currency [Member] | Designated as Hedging Instrument [Member] |  |
Disclosure of detailed information about hedged items [line items] |  |
Unrealized gains | 11.2 | 0.0
Foreign Currency [Member] | Not Designated as Hedging Instrument [Member] |  |
Disclosure of detailed information about hedged items [line items] |  |
Unrealized gains | $ 2.1 | $ 2.3

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- Definition Unrealized Gain (Loss) on Derivatives1 + References No definition available. + Details
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- Details
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- Details
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- Details
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