Derivative Instruments - Derivative Assets and Liabilities (Details) $ in Millions	Mar. 31, 2021 USD ($) MMBTU bbl rins	Dec. 31, 2020 USD ($) rins bbl MMBTU
Derivatives, Fair Value [Line Items]
Assets	$ 2,248.3	$ 1,431.3
Liabilities	(2,118.2)	(1,409.5)
Counterparty netting and cash collateral, Assets	2,097.7	1,358.3
Counterparty netting and cash collateral, Liabilities	(2,095.9)	(1,373.1)
Total net fair value of derivative assets	150.6	73.0
Total net fair value of derivative liabilities	(22.3)	(36.4)
Footnote:
Cash obligation	$ (1.8)
Cash collateral		$ 14.8
Commodity contracts \| Oil
Footnote:
Derivative, Nonmonetary Notional Amount \| bbl	160,365,527	159,682,606
Commodity contracts \| Natural Gas
Footnote:
Derivative, Nonmonetary Notional Amount \| MMBTU	0	22,130,000
RINs commitment contracts
Footnote:
Derivative, Nonmonetary Notional Amount \| rins	281,608,496	282,150,000
Derivatives not designated as hedging instruments: \| Commodity contracts \| Other current assets
Derivatives, Fair Value [Line Items]
Assets	$ 509.2	$ 48.9
Liabilities	479.3	24.8
Derivatives not designated as hedging instruments: \| Commodity contracts \| Other current liabilities
Derivatives, Fair Value [Line Items]
Assets	959.9	930.7
Liabilities	(970.5)	943.8
Derivatives not designated as hedging instruments: \| Commodity contracts \| Other long-term assets
Derivatives, Fair Value [Line Items]
Assets	2.3	2.4
Liabilities	(2.2)	2.3
Derivatives not designated as hedging instruments: \| Commodity contracts \| Other long-term liabilities
Derivatives, Fair Value [Line Items]
Assets	654.4	415.2
Liabilities	(654.6)	(415.8)
Derivatives not designated as hedging instruments: \| RINs commitment contracts \| Other current assets
Derivatives, Fair Value [Line Items]
Assets	122.5	33.6
Liabilities	0.0	0.0
Derivatives not designated as hedging instruments: \| RINs commitment contracts \| Other current liabilities
Derivatives, Fair Value [Line Items]
Assets	0.0	0.0
Liabilities	$ (11.6)	$ (22.5)
Derivatives designated as hedging instruments: \| Commodity contracts \| Oil
Footnote:
Derivative, Nonmonetary Notional Amount \| bbl	0	0
Derivatives designated as hedging instruments: \| Commodity contracts \| Other current assets
Derivatives, Fair Value [Line Items]
Assets	$ 0.0	$ 0.5
Liabilities	$ 0.0	$ (0.3)

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