v3.25.4
Segment, Major Customer and Major Supplier Information - Income from Reportable Segments (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2025
Dec. 31, 2024
Segment Reporting Information [Line Items]        
Adjusted EBITDA $ 348 $ 367 $ 1,186 $ 1,329
Depreciation and amortization (155) (142) (455) (423)
Interest expense and amortization of debt issuance costs (66) (66) (201) (210)
Adjustment to reconcile proportional consolidation (12) (9) (39) (34)
Unrealized (losses) gains on change in fair value of derivative instruments, net 33 (18) 70 (34)
Realized gains (losses) on derivative instruments not included in Adjusted EBITDA(2) 1 (1) 7 (6)
Restructuring and impairment expenses, net (20) (6) (136) (46)
Loss on sale or disposal of assets, net 0 0 (3) (2)
Metal price lag 126 0 324 14
Start Up Cost (12) 0 (25) 0
Other, net (3) (7) (12) (11)
(Loss) income before income tax provision (155) 149 215 539
Income tax provision (4) (39) (115) (150)
Net income attributable to noncontrolling interests (1) 0 (1) 0
Net income (loss) attributable to our common shareholder (160) 110 99 389
Loss on extinguishment of debt, net 0 0 (3) 0
Sierre flood        
Segment Reporting Information [Line Items]        
Losses, net of recoveries (2) (5) (10) (106)
September Oswego fire losses, net of recoveries        
Segment Reporting Information [Line Items]        
Losses, net of recoveries (300) 0 (321) 0
November Oswego fire losses, net of recoveries        
Segment Reporting Information [Line Items]        
Losses, net of recoveries (27) 0 (27) 0
Operating Segments        
Segment Reporting Information [Line Items]        
Depreciation and amortization (159) (143) (471) (432)
Income tax provision 46 (32) (13) (116)
Operating Segments | North America        
Segment Reporting Information [Line Items]        
Adjusted EBITDA 94 122 361 490
Depreciation and amortization (66) (56) (194) (170)
Restructuring and impairment expenses, net     (58) (26)
Income tax provision 87 5 84 (3)
Operating Segments | Europe        
Segment Reporting Information [Line Items]        
Adjusted EBITDA 78 49 229 202
Depreciation and amortization (45) (42) (134) (126)
Restructuring and impairment expenses, net     (8) 0
Income tax provision (14) (5) (15) 3
Operating Segments | Asia        
Segment Reporting Information [Line Items]        
Adjusted EBITDA 48 75 240 258
Depreciation and amortization (25) (23) (76) (70)
Restructuring and impairment expenses, net     (42) (17)
Income tax provision (4) (12) (22) (40)
Operating Segments | South America        
Segment Reporting Information [Line Items]        
Adjusted EBITDA 130 121 357 375
Depreciation and amortization (23) (22) (67) (66)
Restructuring and impairment expenses, net     (2) (3)
Income tax provision (23) (20) (60) (76)
Eliminations and Other        
Segment Reporting Information [Line Items]        
Adjusted EBITDA (2) 0 (1) 4
Depreciation and amortization 4 1 16 9
Income tax provision $ (50) $ (7) $ (102) $ (34)