Inventory (Major Classes of Inventory) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Raw materials and starting stock	$ 7,154	$ 5,769
Semi-finished and finished steel products	79,936	77,510
Operating materials	10,365	9,893
Gross inventory	97,455	93,172
Inventory reserves	(2,107)	(1,830)
Total inventory, net	$ 95,348	$ 91,342