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v3.23.1

Per Share Information (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions | 3 Months Ended |  |
--- | --- | --- | ---
Mar. 31, 2023 | Mar. 31, 2022 | Dec. 31, 2022 | Feb. 02, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |
Net income attributable to ATI | $ 70.1 | $ 30.9 |  |
Net income attributable to ATI after assumed conversions | $ 72.7 | $ 34.9 |  |
Denominator for basic net income per common share – weighted average shares | 128.5 | 126.4 |  |
Share-based compensation | 2.8 | 1.8 |  |
Denominator for diluted net income per common share – adjusted weighted average shares and assumed conversions | 150.1 | 152.8 |  |
Basic net income attributable to ATI per common share (in dollars per share) | $ 0.55 | $ 0.24 |  |
Diluted net income attributable to ATI per common share (in dollars per share) | $ 0.48 | $ 0.23 |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share Amount | 0.0 | 0.0 |  |
Purchase of treasury stock | $ (10.1) | $ (89.9) |  |
Stock repurchase plan, authorized amount |  |  |  | $ 150.0
Treasury Stock, Shares, Acquired | 0.2 | 3.5 |  |
4.75% Convertible Senior Notes due 2022 |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |
Convertible Senior Notes- Effect on numerator | $ 0.0 | $ 1.1 |  |
Convertible Senior Notes- Effect on denominator | 0.0 | 5.8 |  |
Interest rate |  | 4.75% |  |
ATI Inc. 3.5% Convertible Senior Notes due 2025 |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |
Convertible Senior Notes- Effect on numerator | $ 2.6 | $ 2.9 |  |
Convertible Senior Notes- Effect on denominator | 18.8 | 18.8 |  |
ATI Inc. 3.5% Convertible Senior Notes due 2025 | Convertible Debt |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |
Interest rate | 3.50% |  | 3.50% |

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