Inventory - Carrying Value (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Inventory [Line Items]
Total inventories	$ 881.5	$ 808.4
Refining
Inventory [Line Items]
Refinery raw materials and supplies	385.1	308.0
Refinery work in process	92.8	79.2
Finished goods	355.7	366.4
Retail fuel	8.3	8.3
Retail merchandise	26.9	25.6
Logistics
Inventory [Line Items]
Finished goods	$ 12.7	$ 20.9

Carrying amount as of the balance sheet date of petroleum or crude oil.

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Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of merchandise or goods held by the company that are readily available for sale.

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Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

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Aggregated amount of unprocessed materials to be used in manufacturing or production process and supplies that will be consumed. This amount is net of valuation reserves and adjustments.

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Carrying amount, net of reserves and adjustments, as of the balance sheet date of merchandise or goods which are partially completed. This inventory is generally comprised of raw materials, labor and factory overhead costs, which require further materials, labor and overhead to be converted into finished goods, and which generally require the use of estimates to determine percentage complete and pricing.

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Carrying amount as of the balance sheet date of merchandise inventory purchased by a retailer, wholesaler or distributor and held for future sale.

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