Gratuity and other post-employment benefit plans - Summary of Sensitivity Analysis for Significant Actuarial Assumptions (Detail) - Defined Benefit Gratuity Plan [Member] ₨ in Millions, $ in Millions |
Mar. 31, 2025
INR (₨)
|
Mar. 31, 2025
USD ($)
|
Mar. 31, 2024
INR (₨)
|
|---|---|---|---|
| Actuarial Assumption of Discount Rates [Member] | |||
| Disclosure of sensitivity analysis for actuarial assumptions [line items] | |||
| Increase in discount rate | 0.50% | 0.50% | |
| Decrease in discount rate | 0.50% | 0.50% | |
| Increase in salary escalation | ₨ 314 | $ 4 | ₨ 289 |
| Decrease in salary escalation | ₨ 330 | $ 4 | 312 |
| Actuarial assumption of expected rates of salary increases [member] | |||
| Disclosure of sensitivity analysis for actuarial assumptions [line items] | |||
| Increase in discount rate | 0.50% | 0.50% | |
| Decrease in discount rate | 0.50% | 0.50% | |
| Increase in salary escalation | ₨ 328 | $ 4 | 309 |
| Decrease in salary escalation | ₨ 316 | $ 4 | ₨ 292 |