v3.25.2
Other equity - Summary of Retained Earnings / (Losses) (Detail)
₨ in Millions, $ in Millions
 12 Months Ended
Mar. 31, 2025
INR (₨)
Mar. 31, 2025
USD ($)
Mar. 31, 2024
INR (₨)
Mar. 31, 2023
INR (₨)
Disclosure Of Detailed Information About Retained Earnings Of Equity [line Items]        
Profit (Loss) for the year ₨ 3,814 $ 45 ₨ 3,404 ₨ (4,817)
Adjustments / impact pursuant to the Transaction:        
Change in fair value of put option liability / derecognition of non-controlling interests (435)   (1,526) 3,156
Shares bought back, held as treasury stock     (4,926) (13,499)
Retained earnings / (losses)        
Disclosure Of Detailed Information About Retained Earnings Of Equity [line Items]        
Beginning balance (56,433)   (53,610) (38,420)
Profit (Loss) for the year 3,814   3,404 (4,817)
Re-measurement loss on defined benefit plans (net of tax) 40   (14) 2
Forfeiture of vested options 103      
Acquisition of interest by NCI in subsidiaries     30 (31)
Debenture redemption reserve created during the year (759)      
Debenture redemption reserve released on account of repayment of debentures     5 106
Adjustments / impact pursuant to the Transaction:        
Change in fair value of put option liability / derecognition of non-controlling interests (215)   (1,380) 3,034
Shares bought back, held as treasury stock     (4,926) (13,499)
Allocation to non controlling interest (305)   58 15
Ending balance ₨ (53,755) $ (629) ₨ (56,433) ₨ (53,610)