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Derivative Financial Instruments (Textuals) (Details) € in Millions, ¥ in Millions, $ in Millions, $ in Millions | 3 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Mar. 31, 2019 EUR (€) MBbls $ / bbl | Mar. 31, 2019 JPY (¥) | Mar. 31, 2019 USD ($) | Mar. 31, 2019 SGD ($) MBbls $ / bbl | Mar. 31, 2019 JPY (¥) MBbls $ / bbl | Mar. 31, 2019 USD ($) MBbls $ / bbl | Jan. 31, 2019 MBbls | Dec. 31, 2018 EUR (€) | Dec. 31, 2018 SGD ($) | Dec. 31, 2018 USD ($) | Apr. 24, 2018 MBbls | Nov. 22, 2017 MBbls
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Gain (Loss) on Foreign Currency Fair Value Hedge Derivatives |  |  | $ 4.8 |  |  |  |  |  |  |  |  |
Debt EUR Denominated [Member] |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Notional amount, nonderivative instruments | € 21.0 |  | 23.6 |  |  |  |  |  |  |  |  |
Cumulative foreign currency translation loss |  |  |  |  |  | $ 0.1 |  |  |  |  |  |
Cumulative foreign currency translation loss, net of tax |  |  |  |  |  | 0.1 |  |  |  |  |  |
Debt Yen Denominated [Member] |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Notional amount, nonderivative instruments |  | ¥ 500.0 | 4.5 |  |  |  |  |  |  |  |  |
Cumulative foreign currency translation loss |  |  |  |  |  | 0.4 |  |  |  |  |  |
Cumulative foreign currency translation loss, net of tax |  |  |  |  |  | $ 0.3 |  |  |  |  |  |
Options Held [Member] |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Derivative, nonmonetary notional amount | MBbls | 108,891 |  |  | 108,891 | 108,891 | 108,891 | 81,459 |  |  |  | 30,612 | 125,166
Gain (Loss) related to call options |  |  | $ 0.1 |  |  |  |  |  |  |  |  |
Derivative, Average Price Risk Option Strike Price | $ / bbl | 66.22 |  |  | 66.22 | 66.22 | 66.22 |  |  |  |  |  |
Euro Member Countries, Euro | Forward Contracts [Member] |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Notional amount | € |  |  |  |  |  |  |  | € 10.0 |  |  |  |
Singapore, Dollars | Forward Contracts [Member] |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Notional amount |  |  |  | $ 601.5 |  |  |  |  | $ 601.5 |  |  |
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 |  |  |  | $ 44.0 |  |  |  |  |  |  |  |
Long [Member] | Designated as Hedging Instrument [Member] | United States of America, Dollars | Foreign Exchange Forward [Member] |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Notional amount |  |  |  |  |  | 31.5 |  |  |  |  |  |
Long [Member] | Designated as Hedging Instrument [Member] | Japan, Yen | Foreign Exchange Forward [Member] |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Notional amount | ¥ |  |  |  |  | ¥ 5,232.0 |  |  |  |  |  |  |
Short [Member] | Designated as Hedging Instrument [Member] | Singapore, Dollars | Foreign Exchange Forward [Member] |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Notional amount | € 6.4 |  |  |  |  | 25.1 |  |  |  |  |  |
Short [Member] | Designated as Hedging Instrument [Member] | United States of America, Dollars | Foreign Exchange Forward [Member] |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Notional amount | 26.8 |  |  |  |  | 0.0 |  |  |  |  |  |
Short [Member] | Designated as Hedging Instrument [Member] | Japan, Yen | Foreign Exchange Forward [Member] |  |  |  |  |  |  |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Notional amount | € 20.5 |  |  |  |  | $ 24.4 |  |  |  |  |  |

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