Acquisition of Dearborn (Details) - Severstal Dearborn [Member] $ in Millions	Sep. 16, 2014 USD ($)
Business Acquisition [Line Items]
Accounts receivable	$ 180.6
Inventory	362.6
Other current assets	3.6
Property, plant and equipment	445.5
Investment in affilates	72.5
Total assets acquired	1,064.8
Accounts payable	(201.4)
Accrued liabilities	(32.8)
Other postretirement benefit obligations	(128.2)
Other non-current liabilities	(12.1)
Total liabilities assumed	(374.5)
Purchase price, net of cash acquired	$ 690.3