Segment Information, Textuals (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]
Charge decrementing prior year LIFO	$ 0.6		$ 2.4
Unrealized gains (losses) on derivatives			4.9	(5.4)
VEBA net periodic pension benefit income	6.1	5.7	11.7	11.3
Fabricated Products
Segment Reporting Information [Line Items]
Unrealized gains (losses) on derivatives	1.5	(4.2)	3.5	(4.9)
United States
Segment Reporting Information [Line Items]
Number of production facilities			11
Canada
Segment Reporting Information [Line Items]
Number of production facilities			1
VEBAs
Segment Reporting Information [Line Items]
VEBA net periodic pension benefit income	$ 6.1	$ 5.7	$ 11.7	$ 11.3