v3.26.1
Share based payment - Schedule of Information about Fair Value of Inputs to Option Pricing Model Share Options Granted (Detail)
12 Months Ended
Mar. 31, 2026
₨ / shares
Mar. 31, 2026
$ / shares
Mar. 31, 2025
$ / shares
Share Based Payment Arrangements [Line Items]      
Dividend yield (%) 0.00% 0.00%  
Weighted average share price (Absolute) | ₨ / shares ₨ 606.96    
Holding Company Stock Option Plans      
Share Based Payment Arrangements [Line Items]      
Dividend yield (%) 0.00% 0.00%  
Weighted average share price (Absolute)   $ 8.17  
2021 Incentive Award Plan      
Share Based Payment Arrangements [Line Items]      
Dividend yield (%) 0.00% 0.00% 0.00%
2025 Employee Stock Option Plan      
Share Based Payment Arrangements [Line Items]      
Dividend yield (%) 0.00% 0.00%  
Expected volatility (%) 60.00% 60.00%  
2025 Employee Share Purchase Plan      
Share Based Payment Arrangements [Line Items]      
Dividend yield (%) 0.00% 0.00%  
Expected volatility (%) 39.63% 39.63%  
Risk–free interest rate (%) 8.28% 8.28%  
Weighted average expected life of options granted 19 years 11 months 1 day 19 years 11 months 1 day  
Weighted average share price (Absolute)   $ 127.43  
Global Incentive Plan 2024      
Share Based Payment Arrangements [Line Items]      
Dividend yield (%) 0.00% 0.00%  
Expected volatility (%) 33.48% 33.48%  
Weighted average expected life of options granted 6 years 6 months 6 years 6 months  
Weighted average share price (Absolute) | ₨ / shares ₨ 29.43    
Bottom of Range      
Share Based Payment Arrangements [Line Items]      
Expected volatility (%) 25.67% 25.67%  
Risk–free interest rate (%) 3.29% 3.29%  
Weighted average expected life of options granted 25 days 25 days  
Bottom of Range | Holding Company Stock Option Plans      
Share Based Payment Arrangements [Line Items]      
Expected volatility (%) 33.43% 33.43%  
Risk–free interest rate (%) 0.05% 0.05%  
Weighted average expected life of options granted 25 days 25 days  
Bottom of Range | 2021 Incentive Award Plan      
Share Based Payment Arrangements [Line Items]      
Expected volatility (%) 29.92% 29.92% 28.52%
Risk–free interest rate (%) 3.73% 3.73% 3.64%
Weighted average expected life of options granted 8 years 8 years 8 years
Weighted average share price (Absolute)   $ 4.5 $ 5.22
Bottom of Range | 2025 Employee Stock Option Plan      
Share Based Payment Arrangements [Line Items]      
Risk–free interest rate (%) 6.04% 6.04%  
Weighted average expected life of options granted 3 years 5 months 8 days 3 years 5 months 8 days  
Weighted average share price (Absolute)   $ 104.67  
Bottom of Range | Global Incentive Plan 2024      
Share Based Payment Arrangements [Line Items]      
Risk–free interest rate (%) 2.56% 2.56%  
Top of Range      
Share Based Payment Arrangements [Line Items]      
Expected volatility (%) 37.87% 37.87%  
Risk–free interest rate (%) 6.39% 6.39%  
Weighted average expected life of options granted 6 years 10 months 9 days 6 years 10 months 9 days  
Top of Range | Holding Company Stock Option Plans      
Share Based Payment Arrangements [Line Items]      
Expected volatility (%) 49.97% 49.97%  
Risk–free interest rate (%) 1.03% 1.03%  
Weighted average expected life of options granted 6 years 10 months 9 days 6 years 10 months 9 days  
Top of Range | 2021 Incentive Award Plan      
Share Based Payment Arrangements [Line Items]      
Expected volatility (%) 33.75% 33.75% 33.90%
Risk–free interest rate (%) 4.00% 4.00% 5.21%
Weighted average expected life of options granted 10 years 10 years 10 years
Weighted average share price (Absolute)   $ 8.19 $ 7.46
Top of Range | 2025 Employee Stock Option Plan      
Share Based Payment Arrangements [Line Items]      
Risk–free interest rate (%) 6.81% 6.81%  
Weighted average expected life of options granted 5 years 1 month 24 days 5 years 1 month 24 days  
Weighted average share price (Absolute)   $ 138  
Top of Range | Global Incentive Plan 2024      
Share Based Payment Arrangements [Line Items]      
Risk–free interest rate (%) 3.10% 3.10%