Finance costs and fair value change in derivative instruments - Summary of Detailed Information About Finance costs and Fair Value Change in Derivative Instruments (Parenthetical) (Detail) - INR (₨) ₨ in Millions |
12 Months Ended | ||
|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
Mar. 31, 2024 |
|
| Disclosure Of Detailed Information About Finance Cost And Fair Value Change in Derivative Instruments [Abstract] | |||
| Interest expense on lease liabilities | ₨ 711 | ₨ 615 | ₨ 690 |
| Premium on redemption on bonds and debentures | ₨ 1,859 | ₨ 2,176 | ₨ 3,080 |