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Derivative Financial Instruments and Hedging - Schedule of Derivative Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Fair value of derivative asset	$ 3.4	$ 16.5
Fair value of derivative liability	10.4	5.5
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative asset	3.0	16.4
Fair value of derivative liability	10.4	5.5
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative asset	0.4	0.1
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member] | Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liability	0.6	0.0
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member] | Prepaid expenses and other current assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative asset	0.4	0.1
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liability	0.2	0.0
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liability	0.3	0.0
Nickel and other raw material contracts [Member] | Designated as Hedging Instrument [Member] | Prepaid expenses and other current assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative asset	1.2	10.5
Nickel and other raw material contracts [Member] | Designated as Hedging Instrument [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative asset	0.8	5.5
Nickel and other raw material contracts [Member] | Designated as Hedging Instrument [Member] | Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liability	6.8	2.1
Nickel and other raw material contracts [Member] | Designated as Hedging Instrument [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liability	2.1	2.2
Natural gas contracts [Member] | Designated as Hedging Instrument [Member] | Prepaid expenses and other current assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative asset	0.8	0.1
Natural gas contracts [Member] | Designated as Hedging Instrument [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative asset	0.2	0.3
Natural gas contracts [Member] | Designated as Hedging Instrument [Member] | Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liability	0.1	0.9
Natural gas contracts [Member] | Designated as Hedging Instrument [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value of derivative liability	$ 0.3	$ 0.3

X

- Definition

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

+ References

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-Name Accounting Standards Codification
-Topic 210
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Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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