v3.26.1
Intangible Assets - Summary of Sensitivity Analysis for Cash Generating Unit (Parenthetical) (Detail)
₨ in Millions, $ in Millions
 12 Months Ended
Mar. 31, 2026
INR (₨)
Mar. 31, 2026
USD ($)
Mar. 31, 2025
INR (₨)
Disclosure of detailed information about intangible assets [line items]      
Impairment loss recognised in profit or loss, intangible assets other than goodwill ₨ 812 $ 9  
Amount by which unit's recoverable amount exceeds its carrying amount ₨ 65,090    
Impairment Test Two [Member]      
Disclosure of detailed information about intangible assets [line items]      
Discount rate used in value in use calculations 12.54%   13.22%
Percentage of currently estimated PLF 27.89%   28.23%
Impairment Test Three [Member]      
Disclosure of detailed information about intangible assets [line items]      
Discount rate used in value in use calculations 12.78%   12.25%
Percentage of currently estimated PLF 23.45%   22.86%
Impairment Test Five [Member] | Bottom of range [member]      
Disclosure of detailed information about intangible assets [line items]      
Discount rate used in value in use calculations 12.39%   12.15%
Percentage of currently estimated PLF 18.13%   18.47%
Impairment Test Five [Member] | Top of range [member]      
Disclosure of detailed information about intangible assets [line items]      
Discount rate used in value in use calculations 14.77%   14.15%
Percentage of currently estimated PLF 24.62%   25.36%
Ostro Energy Group [member]      
Disclosure of detailed information about intangible assets [line items]      
Impairment loss recognised in profit or loss, intangible assets other than goodwill | $   $ 812  
Ostro Energy Group [member] | Impairment Test One [Member]      
Disclosure of detailed information about intangible assets [line items]      
Discount rate used in value in use calculations 12.71%   12.15%
Percentage of currently estimated PLF 26.17%   26.27%
Percentage of increase in discount rate 0.50% 0.50%  
Ostro Energy Group [member] | Impairment Test One [Member] | Discount Rate [Member]      
Disclosure of detailed information about intangible assets [line items]      
Amount by which unit's recoverable amount exceeds its carrying amount ₨ 2,312    
Ostro Energy Group [member] | Impairment Test One [Member] | Pay Load Factor [Member]      
Disclosure of detailed information about intangible assets [line items]      
Percentage of decrease in PLF 0.50% 0.50%  
Amount by which unit's recoverable amount exceeds its carrying amount ₨ 1,565    
3E NV [Member] | Impairment Test Four [Member]      
Disclosure of detailed information about intangible assets [line items]      
Impairment loss recognised in profit or loss, intangible assets other than goodwill ₨ 402   ₨ 603
Percentage of increase in discount rate 0.50% 0.50%  
Estimated revenue growth rate 16.80% 16.80%  
Estimated revenue growth rate five years and thereafter 12.70% 12.70%  
Percentage of terminal growth rate 2.20% 2.20%  
Estimated revenue discount rate five years and thereafter 25.00% 25.00%  
Reduction in revenue growth rate 1.00% 1.00%