Derivative Financial Instruments and Hedging (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Notional Disclosures [Abstract]
Percentage of estimated annual nickel requirements			10.00%
Percentage of forecasted natural gas usage hedged for 2014			70.00%
Percentage Of Forecasted Natural Gas Usage Hedged for 2015			80.00%
Percentage Of Forecasted Natural Gas Usage Hedged for 2016			50.00%
Percentage of Forecasted Natural Gas Usage Hedged for 2017			15.00%
Percentage of on-peak and off-peak electricity hedged			10.00%
Percentage of forecasted international sales hedged			10.00%
Reclassification of Cash Flow Hedge Gain (Loss) [Abstract]
Cash Flow Hedge Gain Loss To Be Reclassified Within Twelve Months			$ 3.0
Other Comprehensive Income | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain Loss Recognized In Other Comprehensive Income Effective Portion Net	7.9	(9.8)	13.6	(1.8)
Cost Of Sales | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain Loss Reclassified From Accumulated OCI Into Income Effective Portion Net	0.3	(0.4)	(1.0)	(0.8)
Selling And Administrative Expenses | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net	0	0	0	0
Nickel and other raw material contracts | Other Comprehensive Income | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain Loss Recognized In Other Comprehensive Income Effective Portion Net	7.1	(7.4)	10.1	(8.8)
Nickel and other raw material contracts | Cost Of Sales | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain Loss Reclassified From Accumulated OCI Into Income Effective Portion Net	0.9	(1.1)	(0.8)	(1.0)
Nickel and other raw material contracts | Selling And Administrative Expenses | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net	0	0	0	0
Natural gas contracts | Other Comprehensive Income | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain Loss Recognized In Other Comprehensive Income Effective Portion Net	(1.0)	(1.9)	1.3	(0.3)
Natural gas contracts | Cost Of Sales | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain Loss Reclassified From Accumulated OCI Into Income Effective Portion Net	1.0	0.1	2.4	(0.9)
Natural gas contracts | Selling And Administrative Expenses | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net	0	0	0	0
Electricity contracts | Other Comprehensive Income | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain Loss Recognized In Other Comprehensive Income Effective Portion Net	(0.1)	(0.1)	0.8	0
Electricity contracts | Cost Of Sales | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain Loss Reclassified From Accumulated OCI Into Income Effective Portion Net	0.1	0	0.5	(0.2)
Electricity contracts | Selling And Administrative Expenses | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net	0	0	0	0
Foreign exchange contracts | Other Comprehensive Income | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain Loss Recognized In Other Comprehensive Income Effective Portion Net	1.9	(0.4)	1.4	7.3
Foreign exchange contracts | Cost Of Sales | Not Designated as Hedging Instrument [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain Loss Recognized In Income Net	0.9	(0.4)	1.1	0.4
Foreign exchange contracts | Cost Of Sales | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain Loss Reclassified From Accumulated OCI Into Income Effective Portion Net	(1.7)	0.6	(3.1)	1.3
Foreign exchange contracts | Selling And Administrative Expenses | Cash Flow Hedging
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net	$ 0	$ 0	$ 0	$ 0