v3.25.2
Investments - Schedule of Method of Fair Valuation (Details) - USD ($)
$ in Millions
 12 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Fair value $ 2,754 $ 2,952
Fair Value    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Fair value 2,774 2,977
Fair Value Through Profit or Loss    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Fair value 309 388
Amortized Cost    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Fair value 193 211
Fair Value Through Other Comprehensive Income    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Fair value $ 2,252 2,353
Liquid Mutual Funds | Fair Value Through Profit or Loss    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Method Quoted price  
Liquid Mutual Funds | Fair Value Through Profit or Loss | Fair Value    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Fair value $ 229 313
Target Maturity Fund Units | Fair Value Through Profit or Loss    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Method Quoted price  
Target Maturity Fund Units | Fair Value Through Profit or Loss | Fair Value    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Fair value $ 54 51
Quoted Debt Securities | Amortized Cost    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Method Quoted price and marketobservable inputs  
Quoted Debt Securities | Amortized Cost | Fair Value    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Fair value $ 213 236
Quoted Debt Securities | Fair Value Through Other Comprehensive Income    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Method Quoted price and marketobservable inputs  
Quoted Debt Securities | Fair Value Through Other Comprehensive Income | Fair Value    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Fair value $ 1,389 1,384
Commercial Paper | Fair Value Through Other Comprehensive Income    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Method Market observable inputs  
Commercial Paper | Fair Value Through Other Comprehensive Income | Fair Value    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Fair value $ 426 579
Certificates of Deposit | Fair Value Through Other Comprehensive Income    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Method Market observable inputs  
Certificates of Deposit | Fair Value Through Other Comprehensive Income | Fair Value    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Fair value $ 410 365
Unquoted Equity and Preference Securities | Fair Value Through Profit or Loss    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Method Discounted cash flows method, Market multiples method, Option pricing model  
Unquoted Equity and Preference Securities | Fair Value Through Profit or Loss | Fair Value    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Fair value $ 3  
Unquoted Equity and Preference Securities | Fair Value Through Other Comprehensive Income    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Method Discounted cash flows method,Market multiples method,Option pricing model  
Unquoted Equity and Preference Securities | Fair Value Through Other Comprehensive Income | Fair Value    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Fair value $ 20 11
Quoted Equity Secutities | Fair Value Through Other Comprehensive Income    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Method Quoted price  
Quoted Equity Secutities | Fair Value Through Other Comprehensive Income | Fair Value    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Fair value $ 7 14
Others | Fair Value Through Profit or Loss    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Method Discounted cash flows method,Market multiples method,Option pricing model  
Others | Fair Value Through Profit or Loss | Fair Value    
Disclosure Of Fair Value Measurement Of Assets [Line Items]    
Fair value $ 23 $ 24