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total foreign country sales from domicile operations

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Amount of gain (loss) from the difference between the sale price or salvage price and the book value of an asset that was sold or retired, and gain (loss) from the write down of assets from their carrying value to fair value.

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The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

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The net cash outflow or inflow associated with the acquisition or sale of a business segment during the period.

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Business Segments - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 29, 2024	Dec. 31, 2023	Jan. 01, 2023
Segment Reporting Information [Line Items]
Gain (loss) on asset sales and sale of business, net	$ 52.9	$ (0.6)	$ (105.4)
Proceeds from sales of businesses, net of transaction costs	48.0	(0.3)	0.3
Restructuring and other credits (charges)	(22.1)	(31.4)	(23.7)
Total international sales	1,836.9	1,922.9	1,617.4
Sales by U.S. operations to foreign countries	1,425.4	1,498.7	1,217.9
Closed operations and other income (expenses)	10.8	(13.3)	(5.6)
Income From Government Assistance, CARES Act			34.0
Employee retention credits	16.7
Selling and administrative expenses	342.3	$ 328.1	297.5
Restructuring Charges, Statement of Income or Comprehensive Income [Extensible Enumeration]		Cost of sales
Gains from disposal of property, plant and equipment, net	11.6	$ 0.3	0.2
Facility Closing
Segment Reporting Information [Line Items]
Depreciation		3.8
Sheffield, UK Operations
Segment Reporting Information [Line Items]
Net gain (loss) on sale of businesses			(112.2)
Pico Rivera, CA Operations
Segment Reporting Information [Line Items]
Proceeds from sale of other assets			6.2
Gain (Loss) on disposition of other assets			6.8
Houston, PA facility
Segment Reporting Information [Line Items]
Gain (loss) on asset sales and sale of business, net	2.3
Proceeds from sale of other assets	3.5
New Bedford, MA and Remscheid, Germany
Segment Reporting Information [Line Items]
Net gain (loss) on sale of businesses	52.9
Proceeds from sale of businesses, net of transaction costs	48.0
HPMC
Segment Reporting Information [Line Items]
Employee Retention Credits, Aviation Manufacturing Jobs Protection Program			27.0
Employee retention credits	9.0
AA&S
Segment Reporting Information [Line Items]
Employee retention credits	$ 7.7		7.0
Allegheny & Tsingshan Stainless
Segment Reporting Information [Line Items]
Equity method investment ownership percentage	50.00%
Operating Segments
Segment Reporting Information [Line Items]
Depreciation	$ 118.8	117.4	$ 115.4
Operating Segments \| Commercial Negotiations With a Customer
Segment Reporting Information [Line Items]
Selling and administrative expenses	11.8
Operating Segments \| HPMC \| Commercial Negotiations With a Customer
Segment Reporting Information [Line Items]
Selling and administrative expenses	6.3
Operating Segments \| AA&S
Segment Reporting Information [Line Items]
Tax benefits	22.7	$ 10.1
Operating Segments \| AA&S \| Commercial Negotiations With a Customer
Segment Reporting Information [Line Items]
Selling and administrative expenses	$ 5.5
Aerospace & Defense Market Concentration Risk [Member] \| Revenue Benchmark [Member] \| HPMC
Segment Reporting Information [Line Items]
Percentage of sales	86.00%
Commercial Jet Engines Concentration \| Revenue Benchmark [Member] \| HPMC
Segment Reporting Information [Line Items]
Percentage of sales	60.00%
Defense Market Concentration \| Revenue Benchmark [Member] \| HPMC
Segment Reporting Information [Line Items]
Percentage of sales	10.00%
Core End Markets \| Revenue Benchmark [Member] \| AA&S
Segment Reporting Information [Line Items]
Percentage of sales	60.00%
Industrial Markets \| Revenue Benchmark [Member] \| AA&S
Segment Reporting Information [Line Items]
Percentage of sales	40.00%
Allegheny Technologies Inc \| STAL Precision Stainless Steel Company Limited [Member]
Segment Reporting Information [Line Items]
Joint venture ownership percentage	60.00%