Employee Benefits, Net Periodic Benefit Costs and Charges Relating To Other Benefit Plans(Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
VEBAs:
Total net periodic pension benefit income relating to VEBAs			$ (8.9)	$ (4.5)
Deferred compensation plan	0.3	(0.3)	0.8	(0.1)
Defined contribution plans	1.3	1.2	6.3	5.9
Multiemployer pension plans	0.9	0.8	2.6	2.3
Total	(0.4)	0.2	0.8	3.6
Fabricated Products
VEBAs:
Total	2.1	1.7	8.5	7.4
All Other
VEBAs:
Total	(2.5)	(1.5)	(7.7)	(3.8)
VEBAs
VEBAs:
Service cost	0.9	0.6	2.6	1.7
Interest cost	4.4	4.4	13.4	13.1
Expected return on plan assets	(10.0)	(7.6)	(30.3)	(22.8)
Amortization of prior service cost	1.0	1.0	3.1	3.1
Amortization of net actuarial loss	0.8	0.1	2.3	0.4
Total net periodic pension benefit income relating to VEBAs	$ (2.9)	$ (1.5)	$ (8.9)	$ (4.5)