v3.25.2
Retirement benefits - Plan Assets as Percentage of Total Funds (Detail) - Gratuity
Mar. 31, 2025
Funds managed by insurance company (1)  
Defined Benefit Plan Disclosure [Line Items]  
Plan asset as percentage of total funds 100.00% [1]
Funds managed by insurance company (1) | Government Securities  
Defined Benefit Plan Disclosure [Line Items]  
Plan asset as percentage of total funds 75.20% [1]
Funds managed by insurance company (1) | Debenture and bonds  
Defined Benefit Plan Disclosure [Line Items]  
Plan asset as percentage of total funds 8.60% [1]
Funds managed by insurance company (1) | Equity securities  
Defined Benefit Plan Disclosure [Line Items]  
Plan asset as percentage of total funds 9.90% [1]
Funds managed by insurance company (1) | Other  
Defined Benefit Plan Disclosure [Line Items]  
Plan asset as percentage of total funds 6.30% [1]
Funds managed by insurance company (2)  
Defined Benefit Plan Disclosure [Line Items]  
Plan asset as percentage of total funds 100.00% [1]
Funds managed by insurance company (2) | Government Securities  
Defined Benefit Plan Disclosure [Line Items]  
Plan asset as percentage of total funds 44.60% [1]
Funds managed by insurance company (2) | Debenture and bonds  
Defined Benefit Plan Disclosure [Line Items]  
Plan asset as percentage of total funds 13.80% [1]
Funds managed by insurance company (2) | Equity securities  
Defined Benefit Plan Disclosure [Line Items]  
Plan asset as percentage of total funds 39.20% [1]
Funds managed by insurance company (2) | Other  
Defined Benefit Plan Disclosure [Line Items]  
Plan asset as percentage of total funds 2.40% [1]
Funds managed by trust  
Defined Benefit Plan Disclosure [Line Items]  
Plan asset as percentage of total funds 100.00%
Funds managed by trust | Government Securities  
Defined Benefit Plan Disclosure [Line Items]  
Plan asset as percentage of total funds 45.30%
Funds managed by trust | Debenture and bonds  
Defined Benefit Plan Disclosure [Line Items]  
Plan asset as percentage of total funds 30.50%
Funds managed by trust | Equity securities  
Defined Benefit Plan Disclosure [Line Items]  
Plan asset as percentage of total funds 5.10%
Funds managed by trust | Other  
Defined Benefit Plan Disclosure [Line Items]  
Plan asset as percentage of total funds 19.10%
[1] The data pertaining to plan investment assets measured at fair value by level and total at March 31, 2025 are provided separately.