v3.26.1
Intangible Assets - Summary of Break-Up of Carrying Value of Goodwill and Intangible Assets (Detail) - USD ($)
$ in Millions
Mar. 31, 2026
Mar. 31, 2025
Disclosure of information for cash-generating units [line items]    
Goodwill $ 16,749 $ 11,596
Ostro Energy Group [member] | Generation and Sale of Renewable Power [Member]    
Disclosure of information for cash-generating units [line items]    
Goodwill 9,091 9,903
ReNew Vayu Urja KCT [member] | Generation and Sale of Renewable Power [Member]    
Disclosure of information for cash-generating units [line items]    
Goodwill 756 756
Prathamesh Solarfarms [member] | Generation and Sale of Renewable Power [Member]    
Disclosure of information for cash-generating units [line items]    
Goodwill 428 428
3E NV [Member] | Software solutions (included in non reportable segment) Member    
Disclosure of information for cash-generating units [line items]    
Goodwill 6,002  
Others [member] | Generation and Sale of Renewable Power [Member]    
Disclosure of information for cash-generating units [line items]    
Goodwill $ 472 $ 509