Inventory (Major Classes of Inventory) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Raw materials and starting stock	$ 11,448	$ 8,527
Semi-finished and finished steel products	102,189	99,820
Operating materials	11,973	10,850
Gross inventory	125,610	119,197
Inventory reserves	(2,771)	(2,534)
Total inventory, net	$ 122,839	$ 116,663

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Amount before valuation reserves of merchandise or goods held by the entity that are readily available for sale and items held by the entity which are partially complete or in the process of being readied for sale.

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Gross amount, as of the balance sheet date, of merchandise, goods, commodities, or supplies held for future sale or to be used in manufacturing, servicing or production process.

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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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Gross amount of unprocessed materials to be used in manufacturing or production process and supplies that will be consumed.

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Amount of valuation reserve for inventory.

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Carrying value of operating materials and supplies as of the Balance Sheet date.

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