v3.26.1
Financial Risk Management - Summary of Carrying Amounts of Group's Notes and Debentures by Currency and Derivatives Which Hedge (Detail) - USD ($)
$ in Millions
 12 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2024
Disclosure of detailed information about hedged items [line items]      
Carrying amount of notes and debentures $ 19,942 $ 18,663  
De-designated hedges [1] 152 186  
Recognised in cash flow hedging reserve 76 16 $ (27)
Recognised in cost of hedging reserve 11 (4) 7
Recognised in the income statement [2] (229) (134)  
Accrued and other cash flows (314) (217)  
Total derivatives fair value 1,067 595  
Hedged value of loans, notes and debentures [3] 21,580 19,779  
Reserve of cash flow hedges gross [member]      
Disclosure of detailed information about hedged items [line items]      
Recognised in cash flow hedging reserve 108 22 (40)
Cost of hedging reserve gross [member]      
Disclosure of detailed information about hedged items [line items]      
Recognised in cost of hedging reserve 16 (6) $ 10
Currency risk [member]      
Disclosure of detailed information about hedged items [line items]      
Risk 527 373  
Interest rate risk [member]      
Disclosure of detailed information about hedged items [line items]      
Risk 959 557  
USD [member]      
Disclosure of detailed information about hedged items [line items]      
Carrying amount of notes and debentures 14,945 15,120  
De-designated hedges [1] 47 49  
Recognised in the income statement [2] (56) (19)  
Accrued and other cash flows (73) (51)  
Total derivatives fair value 468 179  
Hedged value of loans, notes and debentures [3] 15,589 15,418  
USD [member] | Reserve of cash flow hedges gross [member]      
Disclosure of detailed information about hedged items [line items]      
Recognised in cash flow hedging reserve 0 0  
USD [member] | Cost of hedging reserve gross [member]      
Disclosure of detailed information about hedged items [line items]      
Recognised in cost of hedging reserve 0 0  
USD [member] | Currency risk [member]      
Disclosure of detailed information about hedged items [line items]      
Risk 0 0  
USD [member] | Interest rate risk [member]      
Disclosure of detailed information about hedged items [line items]      
Risk 597 249  
GBP [member]      
Disclosure of detailed information about hedged items [line items]      
Carrying amount of notes and debentures 1,000 1,062  
De-designated hedges [1] 37 40  
Recognised in the income statement [2] (78) (64)  
Accrued and other cash flows 35 37  
Total derivatives fair value 556 468  
Hedged value of loans, notes and debentures [3] 1,612 1,611  
GBP [member] | Reserve of cash flow hedges gross [member]      
Disclosure of detailed information about hedged items [line items]      
Recognised in cash flow hedging reserve 20 (19)  
GBP [member] | Cost of hedging reserve gross [member]      
Disclosure of detailed information about hedged items [line items]      
Recognised in cost of hedging reserve 4 5  
GBP [member] | Currency risk [member]      
Disclosure of detailed information about hedged items [line items]      
Risk 298 251  
GBP [member] | Interest rate risk [member]      
Disclosure of detailed information about hedged items [line items]      
Risk 277 258  
EUR [member]      
Disclosure of detailed information about hedged items [line items]      
Carrying amount of notes and debentures 3,997 2,481  
De-designated hedges [1] 68 97  
Recognised in the income statement [2] (95) (51)  
Accrued and other cash flows (276) (203)  
Total derivatives fair value 43 (52)  
Hedged value of loans, notes and debentures [3] 4,379 2,750  
EUR [member] | Reserve of cash flow hedges gross [member]      
Disclosure of detailed information about hedged items [line items]      
Recognised in cash flow hedging reserve 88 41  
EUR [member] | Cost of hedging reserve gross [member]      
Disclosure of detailed information about hedged items [line items]      
Recognised in cost of hedging reserve (12) (11)  
EUR [member] | Currency risk [member]      
Disclosure of detailed information about hedged items [line items]      
Risk 229 122  
EUR [member] | Interest rate risk [member]      
Disclosure of detailed information about hedged items [line items]      
Risk $ 85 $ 50  
[1] Includes accumulated fair value adjustments on de-designated hedges which are amortised to the income statement over the period to the hedged item’s maturity.
[2] Predominantly related to ineffectiveness.
[3] Includes US$200 million (2025: US$525 million) of fixed rate debt not swapped to floating rate that is not in a hedging relationship.