Business Segments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Information [Line Items]
Sales	$ 1,022.5	$ 1,119.0	$ 2,148.0	$ 2,106.3
Operating profit (loss):	39.2	65.2	123.0	108.7
Corporate expenses	(9.2)	(11.7)	(21.0)	(23.2)
Interest expense, net	(26.8)	(28.5)	(53.5)	(57.6)
Closed company and other expenses	(5.5)	(4.3)	(10.9)	(9.3)
Retirement benefit expense	(19.3)	(24.1)	(38.6)	(48.0)
Income (loss) from continuing operations before income tax provision (benefit)	(21.6)	(3.4)	(1.0)	(29.4)
Interest Costs Capitalized	0.5	1.4
High Performance Materials & Components
Segment Reporting Information [Line Items]
Total sales:	511.1	514.1	1,053.9	998.5
Operating profit (loss):	42.6	85.1	118.5	154.2
Flat Rolled Products
Segment Reporting Information [Line Items]
Total sales:	511.4	604.9	1,094.1	1,107.8
Operating profit (loss):	(3.4)	(19.9)	4.5	(45.5)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales:	1,067.0	1,161.9	2,236.6	2,195.6
Operating Segments [Member] | High Performance Materials & Components
Segment Reporting Information [Line Items]
Total sales:	533.5	531.4	1,098.4	1,035.5
Operating Segments [Member] | Flat Rolled Products
Segment Reporting Information [Line Items]
Total sales:	533.5	630.5	1,138.2	1,160.1
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total sales:	44.5	42.9	88.6	89.3
Intersegment Eliminations [Member] | High Performance Materials & Components
Segment Reporting Information [Line Items]
Total sales:	22.4	17.3	44.5	37.0
Intersegment Eliminations [Member] | Flat Rolled Products
Segment Reporting Information [Line Items]
Total sales:	$ 22.1	$ 25.6	$ 44.1	$ 52.3