Derivatives - Assets and Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
Due from affiliates	$ 9.8	$ 30.1
Due from affiliates, noncurrent	3.9	0.5
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative asset	34.6	19.7
Derivative liability	15.7	4.2
Not Designated as Hedging Instrument [Member] \| Commodity Contract [Member]
Derivative [Line Items]
Derivative asset	34.6	19.7
Derivative liability	15.3	3.6
Not Designated as Hedging Instrument [Member] \| Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative asset	0.0	0.0
Derivative liability	0.4	0.6
Glencore [Member] \| Commodity Contract [Member]
Derivative [Line Items]
Due from affiliates	1.5	0.2
Due from affiliates, noncurrent	$ 3.9	$ 0.5

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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The aggregate amount of receivables to be collected from related parties where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth, at the financial statement date. which are usually due within one year (or one business cycle).

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Aggregate amount of receivables to be collected from related parties where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth, at the financial statement date. which are usually due after one year (or one business cycle).

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