Segment Information, Textuals (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Segment Reporting Information [Line Items]
Unrealized gains (losses) on derivatives			$ 3.6	$ (2.3)
VEBA net periodic pension benefit income	6.0	5.6	17.7	16.9
Fabricated Products
Segment Reporting Information [Line Items]
Unrealized gains (losses) on derivatives	(3.5)	1.5	0	(3.4)
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	$ 6.0	$ 5.6	$ 17.7	$ 16.9