Accumulated Other Comprehensive Income (Loss) - Schedule of Schedule of Reclassifications Out of AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 28, 2025	Dec. 29, 2024	Dec. 31, 2023
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Nonoperating retirement benefit expense	$ (34.6)	$ (29.0)	$ (79.7)
Cost of sales	(3,580.4)	(3,463.9)	(3,371.1)
Interest expense, net	(98.6)	(108.2)	(92.8)
Income before income taxes	522.3	486.1	295.2
Income tax provision (benefit)	103.7	103.4	(128.2)
Net income	418.6	382.7	423.4
Reclassification out of Accumulated Other Comprehensive Income | Postretirement benefit plans Revised
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	(4.6)	(4.7)	(6.5)
Income tax provision (benefit)	(1.1)	(1.1)	(1.4)
Net income	(3.5)	(3.6)	(5.1)
Reclassification out of Accumulated Other Comprehensive Income | Prior service credit
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Nonoperating retirement benefit expense	0.5	0.5	0.6
Reclassification out of Accumulated Other Comprehensive Income | Actuarial losses
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Nonoperating retirement benefit expense	(5.1)	(5.2)	(6.0)
Reclassification out of Accumulated Other Comprehensive Income | Settlement loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Nonoperating retirement benefit expense	0.0	0.0	(1.1)
Reclassification out of Accumulated Other Comprehensive Income | Currency translation adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income	(5.1)	0.0	0.0
Reclassification out of Accumulated Other Comprehensive Income | Derivatives
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	(5.3)	(11.0)	(2.5)
Income tax provision (benefit)	(1.2)	(2.6)	(0.6)
Net income	(4.1)	(8.4)	(1.9)
Reclassification out of Accumulated Other Comprehensive Income | Derivatives | Nickel and other raw material contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of sales	(5.1)	(4.8)	3.3
Reclassification out of Accumulated Other Comprehensive Income | Derivatives | Natural gas contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of sales	(0.4)	(8.0)	(7.5)
Reclassification out of Accumulated Other Comprehensive Income | Derivatives | Foreign exchange contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of sales	0.2	0.2	0.3
Reclassification out of Accumulated Other Comprehensive Income | Derivatives | Interest rate swap
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense, net	$ 0.0	$ 1.6	$ 1.4