v3.25.2
Deferred tax assets (DTA) (net) / deferred tax liabilities (DTL) (net) - Summary of Differed Tax Assets (Net) (Detail)
₨ in Millions, $ in Millions
Mar. 31, 2025
INR (₨)
Mar. 31, 2025
USD ($)
Mar. 31, 2024
INR (₨)
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities ₨ 24,481 $ 287 ₨ 18,705
Net Deferred Tax Assets      
Deferred Tax Assets [Abstract]      
Deferred tax assets (net) 7,073 83 5,556
Net Deferred Tax Assets | Deferred Tax Assets      
Deferred Tax Assets [Abstract]      
Deferred tax assets (net) 29,521 346 24,218
Net Deferred Tax Assets | Deferred Tax Assets | Compound financial instruments      
Deferred Tax Assets [Abstract]      
Deferred tax assets (net) 3,466 41 3,113
Net Deferred Tax Assets | Deferred Tax Assets | Mark to market of derivative instruments      
Deferred Tax Assets [Abstract]      
Deferred tax assets (net) 151 2 78
Net Deferred Tax Assets | Deferred Tax Assets | Difference in written down value of PPE as per books of account and tax laws      
Deferred Tax Assets [Abstract]      
Deferred tax assets (net) 70 1 358
Net Deferred Tax Assets | Deferred Tax Assets | Unamortised ancillary borrowing cost      
Deferred Tax Assets [Abstract]      
Deferred tax assets (net) 1 0 1
Net Deferred Tax Assets | Deferred Tax Assets | Provision for decommissioning costs      
Deferred Tax Assets [Abstract]      
Deferred tax assets (net) 592 7 811
Net Deferred Tax Assets | Deferred Tax Assets | Expected credit losses      
Deferred Tax Assets [Abstract]      
Deferred tax assets (net) 182 2 53
Net Deferred Tax Assets | Deferred Tax Assets | Losses and unabsorbed depreciation available for offsetting against future taxable income      
Deferred Tax Assets [Abstract]      
Deferred tax assets (net) 23,926 280 18,828
Net Deferred Tax Assets | Deferred Tax Assets | Unused tax credt (Minimum alternate tax)      
Deferred Tax Assets [Abstract]      
Deferred tax assets (net) 292 3 167
Net Deferred Tax Assets | Deferred Tax Assets | Lease liabilities      
Deferred Tax Assets [Abstract]      
Deferred tax assets (net) 666 8 377
Net Deferred Tax Assets | Deferred Tax Assets | Others      
Deferred Tax Assets [Abstract]      
Deferred tax assets (net) 175 2 432
Net Deferred Tax Assets | Deferred Tax Liabilities      
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities 22,448 263 18,662
Net Deferred Tax Assets | Deferred Tax Liabilities | Mark to market of derivative instruments      
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities 667 8 37
Net Deferred Tax Assets | Deferred Tax Liabilities | Difference in written down value of PPE as per books of account and tax laws      
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities 20,906 245 17,923
Net Deferred Tax Assets | Deferred Tax Liabilities | Unamortised ancillary borrowing cost      
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities 99 1 142
Net Deferred Tax Assets | Deferred Tax Liabilities | Right of use asset      
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities 712 8 522
Net Deferred Tax Assets | Deferred Tax Liabilities | Others      
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities ₨ 64 $ 1 ₨ 38