Financial Instruments - Summary of Changes in Level 3 Assets and Liabilities (Parenthetical) (Detail) - INR (₨) ₨ in Millions |
12 Months Ended | |
|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
|
| Disclosure of detailed information about financial instruments [line items] | ||
| Investments sold during the year | ₨ 585 | ₨ 1,281 |
| Cumulative loss in statement of income on disposal of investments | 138 | |
| Cumulative loss in other comprehensive income on disposal of investments | 175 | |
| Cumulative gain in statement of income on disposal of investments | ₨ 152 | |
| Cumulative gain in other comprehensive income on disposal of investments | ₨ 389 | |