v3.26.1
Segment, Geographical Area, Major Customer and Major Supplier Information (Income Reconciliation) (Details) - USD ($)
$ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Reconciliation of income from reportable segments to net income attributable to common shareholder      
Adjusted EBITDA $ 1,645 $ 1,802 $ 1,873
Depreciation and amortization (616) (575) (554)
Interest expense and amortization of debt issuance costs (265) (275) (298)
Adjustment to reconcile proportional consolidation (55) (47) (44)
Unrealized (losses) gains on change in fair value of derivative instruments, net (77) 57 (36)
Realized losses (gains) on derivative instruments not included in Adjusted EBITDA 8 (5) 6
Gain on sale of business 7 0 0
Loss on extinguishment of debt, net (3) (7) (5)
Restructuring and impairment, net (195) (53) (42)
(Gain) loss on sale or disposal of assets, net 5 (4) (6)
Metal price lag 515 69 (70)
Other, net (17) (15) (6)
Income before income tax provision 16 842 818
Income tax provision (1) (159) (218)
Net income attributable to our common shareholder 15 683 600
Other nonrecurring expense 10    
Start Up Cost (38) 0 0
Sierre flood      
Reconciliation of income from reportable segments to net income attributable to common shareholder      
Sierre flood losses, net of recoveries 27 (105) 0
Fire      
Reconciliation of income from reportable segments to net income attributable to common shareholder      
Sierre flood losses, net of recoveries (925) 0 0
Operating Segments      
Reconciliation of income from reportable segments to net income attributable to common shareholder      
Depreciation and amortization (639) (586) (567)
Income tax provision 33 (186) (152)
Operating Segments | North America Segment      
Reconciliation of income from reportable segments to net income attributable to common shareholder      
Adjusted EBITDA 435 640 749
Depreciation and amortization (261) (231) (228)
Restructuring and impairment, net (87) (30) (35)
Income tax provision 232 (4) 16
Operating Segments | Europe Segment      
Reconciliation of income from reportable segments to net income attributable to common shareholder      
Adjusted EBITDA 379 306 321
Depreciation and amortization (185) (173) (167)
Restructuring and impairment, net (31) (1) (2)
Income tax provision (56) (28) (40)
Operating Segments | Asia Segment      
Reconciliation of income from reportable segments to net income attributable to common shareholder      
Adjusted EBITDA 311 347 334
Depreciation and amortization (102) (94) (91)
Restructuring and impairment, net (43) (17) 0
Income tax provision (45) (55) (36)
Operating Segments | South America      
Reconciliation of income from reportable segments to net income attributable to common shareholder      
Adjusted EBITDA 521 504 472
Depreciation and amortization (91) (88) (81)
Restructuring and impairment, net (2) (3) (5)
Income tax provision (98) (99) (92)
Intersegment eliminations      
Reconciliation of income from reportable segments to net income attributable to common shareholder      
Adjusted EBITDA (1) 5 (3)
Depreciation and amortization 23 11 13
Income tax provision $ (34) $ 27 $ (66)