v3.26.1
Other equity - Summary of Hedge Reserve (Detail) - Hedge reserve
₨ in Millions, $ in Millions
12 Months Ended
Mar. 31, 2026
INR (₨)
Mar. 31, 2026
USD ($)
Mar. 31, 2025
INR (₨)
Mar. 31, 2024
INR (₨)
Disclosure Of Detailed Information About Reserve Of Cash Flow Hedges Of Equity [line Items]        
Beginning balance ₨ (590)   ₨ (1,867) ₨ (618)
OCI for the year 1,227   (97) (2,205)
Attributable to non-controlling interests (67)   (53) 129
Amount transferred to property, plant and equipment 513   1,427 827
Ending balance ₨ 1,083 $ 12 ₨ (590) ₨ (1,867)