Summary of Significant Accounting Policies, Textuals (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended			3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013 Fabricated Products	Jun. 30, 2012 Fabricated Products	Jun. 30, 2013 Fabricated Products	Jun. 30, 2012 Fabricated Products
Significant accounting policies [Line Items]
Net non-cash LIFO benefits	$ 12.9	$ 7.8		$ 9.2	$ 4.9	$ 12.9	$ 7.8
Excess of current cost over the stated LIFO value of inventory	$ 11.6		$ 24.5