v3.26.1
Financial Instruments - Summary of Fair Value Hierarchy of Assets and Liabilities Measured at Fair Value of Recurring Basis (Detail) - INR (₨)
₨ in Millions
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Disclosure of fair value measurement of assets and liabilities [line items]      
Contingent consideration ₨ 1,634 ₨ 1,864 ₨ 429
Fair value measurements at reporting date using [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Contingent consideration (1,634) (1,864)  
Fair value measurements at reporting date using [member] | Cash flow hedges [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 593 715  
Fair value of financial liabilities (9,525) (893)  
Fair value measurements at reporting date using [member] | Level 1 [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Contingent consideration 0 0  
Fair value measurements at reporting date using [member] | Level 1 [member] | Cash flow hedges [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 0 0  
Fair value of financial liabilities 0 0  
Fair value measurements at reporting date using [member] | Level 2 [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Contingent consideration 0 0  
Fair value measurements at reporting date using [member] | Level 2 [member] | Cash flow hedges [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 593 715  
Fair value of financial liabilities (9,525) (893)  
Fair value measurements at reporting date using [member] | Level 3 [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Contingent consideration (1,634) (1,864)  
Fair value measurements at reporting date using [member] | Level 3 [member] | Cash flow hedges [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 0 0  
Fair value of financial liabilities 0 0  
Fair value measurements at reporting date using [member] | Derivative Assets - Others [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 295 1,105  
Fair value of financial liabilities (1,453) (75)  
Fair value measurements at reporting date using [member] | Derivative Assets - Others [member] | Level 1 [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 0 0  
Fair value of financial liabilities 0 0  
Fair value measurements at reporting date using [member] | Derivative Assets - Others [member] | Level 2 [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 295 1,105  
Fair value of financial liabilities (1,453) (75)  
Fair value measurements at reporting date using [member] | Derivative Assets - Others [member] | Level 3 [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 0 0  
Fair value of financial liabilities 0 0  
Fair value measurements at reporting date using [member] | ShortTerm Mutual Funds [Member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 79,719 88,776  
Fair value measurements at reporting date using [member] | ShortTerm Mutual Funds [Member] | Level 1 [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 79,719 88,776  
Fair value measurements at reporting date using [member] | ShortTerm Mutual Funds [Member] | Level 2 [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 0 0  
Fair value measurements at reporting date using [member] | ShortTerm Mutual Funds [Member] | Level 3 [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 0 0  
Fair value measurements at reporting date using [member] | Fixed Maturity Plan Mutual Funds [Member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 1,281 1,503  
Fair value measurements at reporting date using [member] | Fixed Maturity Plan Mutual Funds [Member] | Level 1 [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 0 0  
Fair value measurements at reporting date using [member] | Fixed Maturity Plan Mutual Funds [Member] | Level 2 [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 1,281 1,503  
Fair value measurements at reporting date using [member] | Fixed Maturity Plan Mutual Funds [Member] | Level 3 [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 0 0  
Fair value measurements at reporting date using [member] | Equity Instruments [Member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 19,479 17,448  
Fair value measurements at reporting date using [member] | Equity Instruments [Member] | Level 1 [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 36 57  
Fair value measurements at reporting date using [member] | Equity Instruments [Member] | Level 2 [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 0 0  
Fair value measurements at reporting date using [member] | Equity Instruments [Member] | Level 3 [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 19,443 17,391  
Fair value measurements at reporting date using [member] | Non-convertible debentures, government securities, commercial papers and bonds [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 243,888 254,036  
Fair value measurements at reporting date using [member] | Non-convertible debentures, government securities, commercial papers and bonds [member] | Level 1 [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 8,854 10,550  
Fair value measurements at reporting date using [member] | Non-convertible debentures, government securities, commercial papers and bonds [member] | Level 2 [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 235,034 243,486  
Fair value measurements at reporting date using [member] | Non-convertible debentures, government securities, commercial papers and bonds [member] | Level 3 [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial assets 0 0  
Fair value measurements at reporting date using [member] | Liability on written put options to non-controlling interests [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial liabilities (5,699) (4,945)  
Fair value measurements at reporting date using [member] | Liability on written put options to non-controlling interests [member] | Level 1 [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial liabilities 0 0  
Fair value measurements at reporting date using [member] | Liability on written put options to non-controlling interests [member] | Level 2 [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial liabilities 0 0  
Fair value measurements at reporting date using [member] | Liability on written put options to non-controlling interests [member] | Level 3 [member]      
Disclosure of fair value measurement of assets and liabilities [line items]      
Fair value of financial liabilities ₨ (5,699) ₨ (4,945)