XML 70 R60.htm IDEA: XBRL DOCUMENT v3.23.2
Per Share Information (Details) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2023
Jun. 30, 2022
Jun. 30, 2023
Jun. 30, 2022
Apr. 28, 2023
Feb. 02, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]            
Net income (loss) attributable to ATI $ 76.0 $ (38.0) $ 146.1 $ (7.1)    
Net income (loss) attributable to ATI after assumed conversions $ 78.6 $ (38.0) $ 151.3 $ (7.1)    
Denominator for basic net income (loss) per common share – weighted average shares 128.5 124.6 128.5 125.5    
Share-based compensation 2.8 0.0 2.8 0.0    
Denominator for diluted net income (loss) per common share – adjusted weighted average shares and assumed conversions 150.1 124.6 150.1 125.5    
Basic net income (loss) attributable to ATI per common share (in dollars per share) $ 0.59 $ (0.31) $ 1.14 $ (0.06)    
Diluted net income (loss) attributable to ATI per common share (in dollars per share) $ 0.52 $ (0.31) $ 1.01 $ (0.06)    
Antidilutive Securities Excluded from Computation of Earnings Per Share Amount 0.0 26.1 0.0 26.2    
Purchase of treasury stock     $ (10.1) $ (89.9)    
Stock repurchase plan, authorized amount         $ 75.0 $ 150.0
Treasury Stock, Shares, Acquired     0.2 3.5    
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 $ 0.0 $ 5.2 $ 0.0    
Convertible Senior Notes- Effect on denominator 18.8 0.0 18.8 0.0    
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%