v3.25.2
Hedging activities and derivatives - Additional Information (Detail)
€ in Millions, ₨ in Millions, ¥ in Millions, ¥ in Millions, $ in Millions
12 Months Ended
Mar. 31, 2025
INR (₨)
Mar. 31, 2024
INR (₨)
Mar. 31, 2023
INR (₨)
Mar. 31, 2025
USD ($)
Mar. 31, 2025
JPY (¥)
Mar. 31, 2025
EUR (€)
Mar. 31, 2025
CNY (¥)
Mar. 31, 2024
USD ($)
Mar. 31, 2024
JPY (¥)
Mar. 31, 2024
EUR (€)
Mar. 31, 2024
CNY (¥)
Mar. 31, 2023
USD ($)
Disclosure of detailed information about hedges [line items]                        
Gain (loss) on hedge ineffectiveness, recognised in other comprehensive income | ₨ ₨ 287 ₨ (378) ₨ 2,249                  
Deferred tax liability (Asset) on cash flow edges, recognised in other comprehensive income | ₨ ₨ 91 (82) ₨ 564                  
Cash Flow Hedge Reserve | CCS | Senior Secured Notes Included In Short Term Borrowings                        
Disclosure of detailed information about hedges [line items]                        
Hedging instruments, liability       $ 1,892 ¥ 11,845 € 0   $ 1,580 ¥ 0 € 38    
Cash Flow Hedge Reserve | COS | Senior Secured Notes Included In Short Term Borrowings                        
Disclosure of detailed information about hedges [line items]                        
Hedging instruments, liability       851       820        
Cash Flow Hedge Reserve | POS | Senior Secured Notes Included In Short Term Borrowings                        
Disclosure of detailed information about hedges [line items]                        
Hedging instruments, liability       311       355        
Cash Flow Hedge Reserve | Call Spread | Senior Secured Notes Included In Short Term Borrowings                        
Disclosure of detailed information about hedges [line items]                        
Hedging instruments, liability       450     ¥ 202       ¥ 0 $ 450
Cash Flow Hedge Reserve | Foreign Currency Call Options | Senior Secured Notes Included In Short Term Borrowings                        
Disclosure of detailed information about hedges [line items]                        
Hedging instruments, liability       0       $ 658        
Cash Flow Hedge Reserve | Foreign Currency Forwards | Senior Secured Notes Included In Short Term Borrowings                        
Disclosure of detailed information about hedges [line items]                        
Hedging instruments, liability   ₨ 181   $ 167   € 2 ¥ 2,512     € 15 ¥ 3,135  
Loan | Floating interest rate | Receiving interest [member]                        
Disclosure of detailed information about hedges [line items]                        
Borrowings, plus adjustment to interest rate basis       2.61% 2.61% 2.61% 2.61%          
Loan | Floating interest rate | SOFR | Receiving interest [member]                        
Disclosure of detailed information about hedges [line items]                        
Borrowings, plus adjustment to interest rate basis       2.25% 2.25% 2.25% 2.25%          
Loan | Floating interest rate | SOFRA | Receiving interest [member]                        
Disclosure of detailed information about hedges [line items]                        
Borrowings, plus adjustment to interest rate basis       2.00% 2.00% 2.00% 2.00%          
Loan | Floating interest rate | TONA | Receiving interest [member]                        
Disclosure of detailed information about hedges [line items]                        
Borrowings, plus adjustment to interest rate basis       1.40% 1.40% 1.40% 1.40%          
Bottom of range [member] | INR | Senior Secured Notes Included In Short Term Borrowings                        
Disclosure of detailed information about hedges [line items]                        
Borrowings, interest rate       0.91% 0.91% 0.91% 0.91%          
Bottom of range [member] | US [Member] | Senior Secured Notes Included In Short Term Borrowings                        
Disclosure of detailed information about hedges [line items]                        
Borrowings, interest rate       0.85% 0.85% 0.85% 0.85%          
Bottom of range [member] | Loan | Paying interest [member]                        
Disclosure of detailed information about hedges [line items]                        
Borrowings, interest rate       4.68% 4.68% 4.68% 4.68%          
Bottom of range [member] | Loan | Floating interest rate                        
Disclosure of detailed information about hedges [line items]                        
Borrowings, interest rate       2.88% 2.88% 2.88% 2.88%          
Bottom of range [member] | Loan | Floating interest rate | Receiving interest [member]                        
Disclosure of detailed information about hedges [line items]                        
Borrowings, interest rate basis 3 months SOFR                      
Bottom of range [member] | Senior Secured Notes                        
Disclosure of detailed information about hedges [line items]                        
Borrowings, interest rate       4.71% 4.71% 4.71% 4.71%          
Top of range [member] | INR | Senior Secured Notes Included In Short Term Borrowings                        
Disclosure of detailed information about hedges [line items]                        
Borrowings, interest rate       0.38% 0.38% 0.38% 0.38%          
Top of range [member] | US [Member] | Senior Secured Notes Included In Short Term Borrowings                        
Disclosure of detailed information about hedges [line items]                        
Borrowings, interest rate       7.95% 7.95% 7.95% 7.95%          
Top of range [member] | Loan | Paying interest [member]                        
Disclosure of detailed information about hedges [line items]                        
Borrowings, interest rate       9.79% 9.79% 9.79% 9.79%          
Top of range [member] | Loan | Floating interest rate                        
Disclosure of detailed information about hedges [line items]                        
Borrowings, interest rate       7.10% 7.10% 7.10% 7.10%          
Top of range [member] | Senior Secured Notes                        
Disclosure of detailed information about hedges [line items]                        
Borrowings, interest rate       7.95% 7.95% 7.95% 7.95%