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Derivative Financial Instruments and Hedging (Details2) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2025	Sep. 29, 2024	Sep. 28, 2025	Sep. 29, 2024	Dec. 29, 2024
Cash Flow Hedging
Derivatives Fair Value [Line Items]
Amount of gain (loss) reclassified from accumulated OCI into Income	$ (1.4)	$ (2.8)	$ (3.4)	$ (6.1)
Cash Flow Hedging \| Other Comprehensive Income (Loss) [Member]
Derivatives Fair Value [Line Items]
Net derivative gain (loss) on hedge transactions	(2.5)	(1.5)	(1.0)	(3.3)
Nickel and other raw material contracts \| Cash Flow Hedging
Derivatives Fair Value [Line Items]
Amount of gain (loss) reclassified from accumulated OCI into Income	(1.1)	(1.4)	(3.3)	(2.5)
Nickel and other raw material contracts \| Cash Flow Hedging \| Other Comprehensive Income (Loss) [Member]
Derivatives Fair Value [Line Items]
Net derivative gain (loss) on hedge transactions	0.0	(0.2)	(0.7)	(1.3)
Interest Rate Swap \| Cash Flow Hedging
Derivatives Fair Value [Line Items]
Amount of gain (loss) reclassified from accumulated OCI into Income	0.0	0.0	0.0	1.2
Interest Rate Swap \| Cash Flow Hedging \| Other Comprehensive Income (Loss) [Member]
Derivatives Fair Value [Line Items]
Net derivative gain (loss) on hedge transactions	0.0	0.0	0.0	0.0
Natural gas contracts \| Cash Flow Hedging
Derivatives Fair Value [Line Items]
Amount of gain (loss) reclassified from accumulated OCI into Income	(0.3)	(1.4)	(0.2)	(5.0)
Natural gas contracts \| Cash Flow Hedging \| Other Comprehensive Income (Loss) [Member]
Derivatives Fair Value [Line Items]
Net derivative gain (loss) on hedge transactions	(2.6)	(1.1)	(0.2)	(2.1)
Foreign exchange contracts \| Cash Flow Hedging
Derivatives Fair Value [Line Items]
Amount of gain (loss) reclassified from accumulated OCI into Income	0.0	0.0	0.1	0.2
Foreign exchange contracts \| Cash Flow Hedging \| Other Comprehensive Income (Loss) [Member]
Derivatives Fair Value [Line Items]
Net derivative gain (loss) on hedge transactions	0.1	$ (0.2)	(0.1)	$ 0.1
Designated as Hedging Instrument
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Asset	0.9		0.9		$ 1.9
Derivative Fair Value Of Derivative Liability	1.8		1.8		6.0
Designated as Hedging Instrument \| Nickel and other raw material contracts \| Prepaid expenses and other current assets
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Asset	0.1		0.1		0.0
Designated as Hedging Instrument \| Nickel and other raw material contracts \| Other assets
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Asset	0.1		0.1		0.0
Designated as Hedging Instrument \| Nickel and other raw material contracts \| Accrued liabilities
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Liability	1.0		1.0		4.2
Designated as Hedging Instrument \| Nickel and other raw material contracts \| Other long-term liabilities
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Liability	0.1		0.1		0.0
Designated as Hedging Instrument \| Natural gas contracts \| Prepaid expenses and other current assets
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Asset	0.4		0.4		0.8
Designated as Hedging Instrument \| Natural gas contracts \| Other assets
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Asset	0.2		0.2		0.9
Designated as Hedging Instrument \| Natural gas contracts \| Accrued liabilities
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Liability	0.7		0.7		1.7
Designated as Hedging Instrument \| Natural gas contracts \| Other long-term liabilities
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Liability	0.0		0.0		0.1
Designated as Hedging Instrument \| Foreign exchange contracts \| Prepaid expenses and other current assets
Derivatives Fair Value [Line Items]
Derivative Fair Value Of Derivative Asset	$ 0.1		$ 0.1		$ 0.2