Business Segments (Details2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Other Significant Reconciling Item [Line Items]
Depreciation and amortization	$ 189.9	$ 176.8	$ 189.9
Capital expenditures	144.5	225.7	612.7
Operating Segments [Member]
Segment Reporting Other Significant Reconciling Item [Line Items]
Depreciation and amortization	189.9	176.6	180.6
Capital expenditures	144.5	225.7	607.8
Operating Segments [Member] | High Performance Materials & Components [Member]
Segment Reporting Other Significant Reconciling Item [Line Items]
Depreciation and amortization	131.8	124.4	127.4
Capital expenditures	75.8	51.9	39.5
Operating Segments [Member] | Flat Rolled Products [Member]
Segment Reporting Other Significant Reconciling Item [Line Items]
Depreciation and amortization	55.6	49.3	49.5
Capital expenditures	68.0	172.1	568.1
Operating Segments [Member] | Corporate [Member]
Segment Reporting Other Significant Reconciling Item [Line Items]
Depreciation and amortization	2.5	2.9	3.7
Capital expenditures	$ 0.7	$ 1.7	$ 0.2