v3.26.1
Deferred tax assets (DTA) (net) / deferred tax liabilities (DTL) (net) - Summary of Differed Tax Assets (Net) (Detail)
₨ in Millions, $ in Millions
Mar. 31, 2026
INR (₨)
Mar. 31, 2026
USD ($)
Mar. 31, 2025
INR (₨)
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities ₨ 27,127 $ 289 ₨ 24,481
Net Deferred Tax Assets      
Deferred Tax Assets [Abstract]      
Deferred tax assets (net) 10,319 110 7,073
Net Deferred Tax Assets | Deferred Tax Assets      
Deferred Tax Assets [Abstract]      
Deferred tax assets (net) 48,038 512 29,521
Net Deferred Tax Assets | Deferred Tax Assets | Compound financial instruments      
Deferred Tax Assets [Abstract]      
Deferred tax assets (net) 3,459 37 3,466
Net Deferred Tax Assets | Deferred Tax Assets | Mark to market of derivative instruments      
Deferred Tax Assets [Abstract]      
Deferred tax assets (net)     151
Net Deferred Tax Assets | Deferred Tax Assets | Difference in written down value of PPE and intangibles as per books of account and tax laws      
Deferred Tax Assets [Abstract]      
Deferred tax assets (net) 7 0 70
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) 811 9 592
Net Deferred Tax Assets | Deferred Tax Assets | Expected credit losses      
Deferred Tax Assets [Abstract]      
Deferred tax assets (net) 69 1 182
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) 42,017 448 23,926
Net Deferred Tax Assets | Deferred Tax Assets | Unused tax credit (Minimum alternate tax)      
Deferred Tax Assets [Abstract]      
Deferred tax assets (net) 346 4 292
Net Deferred Tax Assets | Deferred Tax Assets | Lease liabilities      
Deferred Tax Assets [Abstract]      
Deferred tax assets (net) 817 9 666
Net Deferred Tax Assets | Deferred Tax Assets | Others      
Deferred Tax Assets [Abstract]      
Deferred tax assets (net) 511 5 175
Net Deferred Tax Assets | Deferred Tax Liabilities      
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities 37,719 402 22,448
Net Deferred Tax Assets | Deferred Tax Liabilities | Mark to market of derivative instruments      
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities 1,006 11 667
Net Deferred Tax Assets | Deferred Tax Liabilities | Difference in written down value of PPE and intangibles as per books of account and tax laws      
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities 35,859 382 20,906
Net Deferred Tax Assets | Deferred Tax Liabilities | Unamortised ancillary borrowing cost      
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities 94 1 99
Net Deferred Tax Assets | Deferred Tax Liabilities | Right of use asset      
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities 700 7 712
Net Deferred Tax Assets | Deferred Tax Liabilities | Others      
Deferred Tax Liabilities [Abstract]      
Deferred tax liabilities ₨ 60 $ 1 ₨ 64