Employee Benefits, Net Periodic Benefit Costs and Charges Relating To All Other Employee Benefit Plans(Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
VEBAs:
Total net periodic postretirement benefit cost (income) relating to VEBAs	$ 0.6	$ (6.0)	$ 1.8	$ (17.7)
Deferred Compensation Arrangement with Individual, Compensation Expense	(0.4)	0.0	0.1	0.6
Defined contribution plans	1.4	1.3	7.1	6.8
Multiemployer pension plans	1.1	0.8	2.9	2.6
Charges Relating To Other Benefit Plans	2.1	2.1	10.1	10.0
Total other employee benefit plans	(0.2)	(3.9)	502.8	(7.7)
Fabricated Products
VEBAs:
Total other employee benefit plans	2.4	2.0	9.4	8.9
All Other
VEBAs:
Total other employee benefit plans	(2.6)	(5.9)	493.4	(16.6)
VEBAs
VEBAs:
Service cost1	0.0	0.6	0.0	1.7
Interest cost	0.7	4.2	2.1	12.5
Expected return on plan assets	(1.1)	(12.9)	(3.3)	(38.5)
Amortization of prior service cost	0.7	2.6	2.2	8.0
Amortization of net actuarial loss (gain)	0.3	(0.5)	0.8	(1.4)
Total net periodic postretirement benefit cost (income) relating to VEBAs	0.6	(6.0)	1.8	(17.7)
Pre-tax loss on settlement of Union VEBA	(2.9)	0.0	490.9	0.0
Total Charges Relating To VEBAs	$ (2.3)	$ (6.0)	$ 492.7	$ (17.7)