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v3.23.1

Business Segments - Additional Information (Details) | 3 Months Ended |
--- | --- | ---
Mar. 31, 2023 USD ($) segment | Mar. 31, 2022 USD ($) | Dec. 31, 2022 USD ($)
Restructuring Cost and Reserve [Line Items] |  |  |
Number of business segments | segment | 2 |  |
Government sponsored COVID relief income |  | $ 29,000,000 |
Gain (Loss) on sale of business | $ 0 | (18,300,000) |
Litigation Reserve | 0 | 8,600,000 |
Restructuring charges (credits) | 0 | (1,100,000) |
Gain (loss) on asset sales and sale of businesses, net | 0 | (18,300,000) |
ATI Inc. 3.5% Convertible Senior Notes due 2025 | Convertible Debt |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |
Debt, Gross | $ 291,400,000 |  | $ 291,400,000
Sheffield, UK Operations |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |
Gain (Loss) on sale of business |  | (25,100,000) |
Pico Rivera, CA Operations |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |
Gain (Loss) on sale of assets |  | 6,800,000 |
High Performance Materials & Components |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |
Employee retention credits and Aviation Manufacturing Jobs Protection Program |  | 22,000,000 |
Advanced Alloys & Solutions |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |
Employee retention credits |  | $ 7,000,000 |

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