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Derivative Financial Instruments (Textuals) (Details) € in Millions, ¥ in Millions, $ in Millions, $ in Millions | 3 Months Ended |  |
--- | --- | --- | ---
Mar. 31, 2018 EUR (€) MBbls | Mar. 31, 2018 JPY (¥) | Mar. 31, 2018 USD ($) | Mar. 31, 2018 SGD ($) MBbls | Mar. 31, 2018 JPY (¥) MBbls | Mar. 31, 2018 USD ($) MBbls | Dec. 31, 2017 EUR (€) MBbls | Dec. 31, 2017 SGD ($) MBbls | Dec. 31, 2017 USD ($) MBbls
Debt EUR Denominated [Member] |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |
Notional amount, nonderivative instruments | € 21.0 |  | $ 25.9 |  |  |  |  |  |
Cumulative foreign currency translation loss |  |  |  |  |  | $ 2.0 |  |  |
Cumulative foreign currency translation loss, net of tax |  |  |  |  |  | 1.6 |  |  |
Debt Yen Denominated [Member] |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |
Notional amount, nonderivative instruments |  | ¥ 500.0 | 4.7 |  |  |  |  |  |
Cumulative foreign currency translation loss |  |  |  |  |  | 0.5 |  |  |
Cumulative foreign currency translation loss, net of tax |  |  |  |  |  | $ 0.4 |  |  |
Options Held [Member] |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |
Derivative, nonmonetary notional amount | MBbls | 96,771 |  |  | 96,771 | 96,771 | 96,771 | 125,166 | 125,166 | 125,166
Loss related to call options |  |  | $ 0.1 |  |  |  |  |  |
Euro Member Countries, Euro | Forward Contracts [Member] |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |
Notional amount | € | € 10.0 |  |  |  |  |  | € 12.0 |  |
Singapore, Dollars | Forward Contracts [Member] |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |
Notional amount |  |  |  | $ 171.0 |  |  |  | $ 171.0 |
United States of America, Dollars | Forward Contracts [Member] |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |
Notional amount |  |  |  |  |  | $ 13.4 |  |  | $ 13.4
Long [Member] | Designated as Hedging Instrument [Member] | Singapore, Dollars | Foreign Exchange Forward [Member] |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |
Notional amount |  |  |  | $ 45.2 |  |  |  |  |
Long [Member] | Designated as Hedging Instrument [Member] | United States of America, Dollars | Foreign Exchange Forward [Member] |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |
Notional amount |  |  |  |  |  | 39.7 |  |  |
Long [Member] | Designated as Hedging Instrument [Member] | Japan, Yen | Foreign Exchange Forward [Member] |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |
Notional amount | ¥ |  |  |  |  | ¥ 7,155.1 |  |  |  |
Short [Member] | Designated as Hedging Instrument [Member] | Singapore, Dollars | Foreign Exchange Forward [Member] |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |
Notional amount | 10.1 |  |  |  |  | 21.6 |  |  |
Short [Member] | Designated as Hedging Instrument [Member] | United States of America, Dollars | Foreign Exchange Forward [Member] |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |
Notional amount | 33.5 |  |  |  |  | 0.0 |  |  |
Short [Member] | Designated as Hedging Instrument [Member] | Japan, Yen | Foreign Exchange Forward [Member] |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |
Notional amount | € 23.9 |  |  |  |  | $ 37.3 |  |  |

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