v3.26.1
Foreign currency translation reserve and other reserves - Summary Of Movement In Other Reserve (Detail)
₨ in Millions, $ in Millions
 12 Months Ended
Dec. 03, 2024
INR (₨)
Mar. 31, 2026
INR (₨)
Mar. 31, 2026
USD ($)
Mar. 31, 2025
INR (₨)
Mar. 31, 2024
INR (₨)
Disclosure of reserves within equity [line items]          
Beginning balance   ₨ 53,497      
Addition through Business combination (Refer to Note 7)   0   ₨ (1,537)  
Other comprehensive income   36,039 $ 384 4,263 ₨ 7,127
Bonus issue of equity shares ₨ 10,467     0 [1]  
Transfer of shares pertaining to Non-controlling interests of subsidiary       0  
Ending balance   89,290 $ 952 53,497  
Remeasurements of the defined benefit plans          
Disclosure of reserves within equity [line items]          
Beginning balance   (135)   (286) (548)
Addition through Business combination (Refer to Note 7)         0
Other comprehensive income   152   289 262
Bonus issue of equity shares       0  
Transfer of shares pertaining to Non-controlling interests of subsidiary       (8)  
Transfer to Retained earnings [2]       (130)  
Buyback of equity shares         0
Ending balance   17   (135) (286)
Investment in Debt instruments measured at fair value through OCI          
Disclosure of reserves within equity [line items]          
Beginning balance   2,360   1,397 (119)
Addition through Business combination (Refer to Note 7)         0
Other comprehensive income   (2,094)   963 1,516
Bonus issue of equity shares       0  
Transfer of shares pertaining to Non-controlling interests of subsidiary       0  
Transfer to Retained earnings [2]       0  
Buyback of equity shares         0
Ending balance   266   2,360 1,397
Investment in Equity instruments measured at fair value through OCI          
Disclosure of reserves within equity [line items]          
Beginning balance   1,220   10,320 10,793
Addition through Business combination (Refer to Note 7)         0
Other comprehensive income   (1,448)   (3,476) (473)
Bonus issue of equity shares       0  
Transfer of shares pertaining to Non-controlling interests of subsidiary       0  
Transfer to Retained earnings [2]       (5,624)  
Buyback of equity shares         0
Ending balance   (228)   1,220 10,320
Capital Redemption Reserve [Member]          
Disclosure of reserves within equity [line items]          
Beginning balance   0   1,661 1,122
Addition through Business combination (Refer to Note 7)         0
Other comprehensive income   0   0 0
Bonus issue of equity shares       (1,661)  
Transfer of shares pertaining to Non-controlling interests of subsidiary       0  
Transfer to Retained earnings [2]       0  
Buyback of equity shares         539
Ending balance   0   0 1,661
Gross obligation to non-controlling interests under put options          
Disclosure of reserves within equity [line items]          
Beginning balance   (4,238)   (4,238) 0
Addition through Business combination (Refer to Note 7)         (4,238)
Other comprehensive income   0   0 0
Bonus issue of equity shares       0  
Transfer of shares pertaining to Non-controlling interests of subsidiary       0  
Transfer to Retained earnings [2]       0  
Buyback of equity shares         0
Ending balance   ₨ (4,238)   ₨ (4,238) ₨ (4,238)
[1] Refer to Note 22
[2] Towards transfer of cumulative realized (gain)/loss on disposal of investments in equity instruments designated as FVTOCI and towards transfer of cumulative (gain)/loss on remeasurement of defined benefit plans to retained earnings.