v3.26.1
Share capital - Summary of Issued Share Capital (Detail)
₨ in Millions, $ in Millions
 12 Months Ended
Mar. 31, 2026
INR (₨)
shares
Mar. 31, 2026
USD ($)
shares
Mar. 31, 2025
INR (₨)
shares
Mar. 31, 2024
INR (₨)
shares
Disclosure Of Reconciliation Of Issued Capital [line Items]        
Beginning balance ₨ 4,808      
Shares issued during the year 542   ₨ 0 ₨ 2
Ending balance 4,808 $ 51 4,808  
Issued capital        
Disclosure Of Reconciliation Of Issued Capital [line Items]        
Shares issued during the year 0   0 0
Share premium        
Disclosure Of Reconciliation Of Issued Capital [line Items]        
Shares issued during the year ₨ 1,161   ₨ 51 ₨ 17
Ordinary Shares | Issued capital        
Disclosure Of Reconciliation Of Issued Capital [line Items]        
Beginning balance, shares | shares 362,769,145 362,769,145 362,630,592 373,037,667
Shares issued during the year, shares | shares 1,633,546 1,633,546 138,553 280,940
Shares forfeited during the year, shares | shares (1) (1)    
Shares bought back, held as treasury stock | shares       (10,688,015)
Ending balance, shares | shares 364,402,690 364,402,690 362,769,145 362,630,592
Beginning balance ₨ 4,808   ₨ 4,808 ₨ 4,808
Shares issued during the year 0   0 0
Shares forfeited during the year (0)      
Shares bought back, held as treasury stock amount       (0)
Ending balance 4,808 $ 51 4,808 4,808
Ordinary Shares | Share premium        
Disclosure Of Reconciliation Of Issued Capital [line Items]        
Beginning balance 154,204   154,153 154,136
Shares issued during the year 1,161   51 17
Shares forfeited during the year 0      
Shares bought back, held as treasury stock amount       0
Ending balance ₨ 155,365 $ 1,656 ₨ 154,204 ₨ 154,153