v3.26.1
Right of use assets (Details)
₨ in Millions, $ in Millions
 12 Months Ended
Mar. 31, 2026
INR (₨)
Mar. 31, 2026
USD ($)
Mar. 31, 2025
INR (₨)
Disclosure of quantitative information about right-of-use assets [line items]      
Begining Balance ₨ 8,822   ₨ 7,258
Additions 1,456   2,692
Deletions (6)   (350)
Depreciation (905)   (778)
Translation Difference 9   0
Ending Balance 9,376 $ 99 8,822
Land [member]      
Disclosure of quantitative information about right-of-use assets [line items]      
Begining Balance 4,313   3,672
Additions 713   784
Deletions 0   (92)
Depreciation (70)   (51)
Translation Difference 0   0
Ending Balance 4,956   4,313
Buildings [Member]      
Disclosure of quantitative information about right-of-use assets [line items]      
Begining Balance 2,290   2,541
Additions 263   400
Deletions (6)   (258)
Depreciation (390)   (393)
Translation Difference 5   0
Ending Balance 2,162   2,290
P&M [member]      
Disclosure of quantitative information about right-of-use assets [line items]      
Begining Balance 1,036   244
Additions 196   978
Deletions 0   0
Depreciation (280)   (186)
Translation Difference 0   0
Ending Balance 952   1,036
IRU [Member]      
Disclosure of quantitative information about right-of-use assets [line items]      
Begining Balance 1,183   801
Additions 284   530
Deletions 0   0
Depreciation (165)   (148)
Translation Difference 4   0
Ending Balance ₨ 1,306   ₨ 1,183