Financial Instruments - Summary of Activity in Cash Flow Hedging Reserve within Equity Related to all Derivative Instruments Classified as Cash Flow Hedges (Detail) - INR (₨) ₨ in Millions |
12 Months Ended | |||
|---|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
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| Disclosure of detailed information about hedges [abstract] | ||||
| Balance as at the beginning of the year | ₨ (275) | ₨ 773 | ||
| Changes in fair value of effective portion of derivatives | (13,440) | (1,185) | ||
| Deferred cancellation gain/(loss), net | (1,174) | (91) | ||
| Net (gain)/loss reclassified to consolidated statement of income on occurrence of hedged transactions | [1] | 5,163 | 203 | |
| Net (gain)/loss on ineffective portion of derivative instruments classified to consolidated statement of income | 0 | 25 | ||
| Translation gain | 7 | 0 | ||
| Gain/(loss) on cash flow hedging derivatives, net | (9,444) | (1,048) | ||
| Balance as at the end of the year | (9,719) | (275) | ||
| Deferred tax asset/(liability) thereon | 2,320 | 65 | ||
| Balance as at the end of the year, net of deferred tax | ₨ (7,399) | ₨ (210) | ||
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