Hedging activities and derivatives - Summary Of Foreign Currency And Interest Rate Risk (Detail) - Hedge Instruments [Member] - INR (₨) ₨ in Millions |
Mar. 31, 2026 |
Mar. 31, 2025 |
|---|---|---|
| Disclosure of detailed information about hedging instruments [line items] | ||
| Derivative contracts designated as hedging instruments - Non-current Asset | ₨ 5,851 | ₨ 3,309 |
| Derivative contracts designated as hedging instruments - Current Assets | 9,724 | 4,089 |
| Derivative contracts designated as hedging instruments - Non-current Liabilities | 89 | 217 |
| Derivative contracts designated as hedging instruments - Current Liabilities | ₨ 28 | ₨ 830 |