Employee Benefits, Net Periodic Benefit Costs and Charges Relating To All Other Employee Benefit Plans(Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
VEBAs:
Total net periodic postretirement benefit cost (income) relating to VEBAs	$ 0.6	$ (6.1)	$ 1.2	$ (11.7)
Pre-tax loss on settlement of Union VEBA		0.0
Deferred compensation plan	0.1	0.4	0.5	0.6
Defined contribution plans	1.7	1.5	5.7	5.5
Multiemployer pension plans	0.9	0.9	1.8	1.8
Charges Relating To Other Benefit Plans	2.7	2.8	8.0	7.9
Total other employee benefit plans	4.9	(3.3)	503.0	(3.8)
Fabricated Products
VEBAs:
Total other employee benefit plans	2.4	2.3	7.0	6.9
All Other
VEBAs:
Total other employee benefit plans	2.5	(5.6)	496.0	(10.7)
VEBAs
VEBAs:
Service cost1	0.0	0.5	0.0	1.1
Interest cost	0.7	4.2	1.4	8.3
Expected return on plan assets	(1.1)	(12.8)	(2.2)	(25.6)
Amortization of prior service cost	0.8	2.6	1.5	5.4
Amortization of net actuarial loss (gain)	0.2	(0.6)	0.5	(0.9)
Total net periodic postretirement benefit cost (income) relating to VEBAs	0.6	(6.1)	1.2	(11.7)
Pre-tax loss on settlement of Union VEBA	1.6	0.0	493.8	0.0
Total Charges Relating To VEBAs	$ 2.2	$ (6.1)	$ 495.0	$ (11.7)