v3.25.2
Hedging activities and derivatives - Summary Of Hedge Reserve Movement (Detail)
₨ in Millions, $ in Millions
 12 Months Ended
Mar. 31, 2025
INR (₨)
Mar. 31, 2025
USD ($)
Mar. 31, 2024
INR (₨)
Mar. 31, 2023
INR (₨)
Mar. 31, 2025
USD ($)
Disclosure of detailed information about hedges [line items]          
Beginning balance ₨ 121,697   ₨ 118,400 ₨ 126,373  
Gain / (loss) recognised on cash flow hedges 633 $ 7 (2,340) 1,487  
Income tax relating on cash flow hedges and cost of hedge reserve (10) (0) (626) 249  
Ending balance 131,112 1,535 121,697 118,400  
Closing balance 112,602   105,217   $ 1,318
Cash Flow Hedge Reserve          
Disclosure of detailed information about hedges [line items]          
Beginning balance 32 0 1,679 668  
Gain / (loss) recognised on cash flow hedges 3,015 35 (2,715) 9,606  
(Gain) / loss reclassified to profit or loss (under head finance costs) (2,370) (28) 406 (8,086)  
(Gain)/loss reclassified to profit or loss on unwinding of derivative contract (12) (0) (11) 57  
(Gain) / loss reclassified to non financial assets or liabilities as basis adjustment (under head property, plant and equipment) (718) (8) (75)    
(Gain) / loss reclassified to profit or loss as hedged future cash flows are no longer expected to occur       (90)  
Income tax relating on cash flow hedges and cost of hedge reserve (12) (0) 594 (336)  
Less: Non-controlling interest movement 35 0 154 (140)  
Ending balance (30) 1 32 1,679  
Closing balance (65)   (122) 1,819 (1)
Cost Of Hedge Reserve On Cash Flow Hedges          
Disclosure of detailed information about hedges [line items]          
Beginning balance (1,899) (22) (2,297) (1,996)  
Effective portion of changes in fair value (2,160) (25) (3,346) (5,923)  
Amount reclassified to profit or loss (under head "Finance costs and fair value change in derivative instruments") 1,420 17 2,435 4,194  
(Gain)/loss reclassified to profit or loss on unwinding of derivative contract 0 0 400 1,340  
(Gain) / loss reclassified to non financial assets or liabilities as basis adjustment (under head property, plant and equipment) 2,624 31 1,177    
(Gain) / loss reclassified to profit or loss as hedged future cash flows are no longer expected to occur       12  
Income tax relating on cash flow hedges and cost of hedge reserve (458) (5) (243) 87  
Less: Non-controlling interest movement (88) (1) (25) (11)  
Ending balance (561) (7) (1,899) (2,297)  
Closing balance (473)   (1,874) (2,286) $ (6)
Total Hedge Reserve [Member]          
Disclosure of detailed information about hedges [line items]          
Beginning balance (1,867) (22) (618) (1,328)  
(Gain) / loss reclassified to non financial assets or liabilities as basis adjustment (under head property, plant and equipment) 1,422 17 827    
OCI for the year (93) (1) (2,205) 861  
Attributable to non-controlling interests (53) (1) 129 (151)  
Ending balance ₨ (591) $ (7) ₨ (1,867) ₨ (618)