v3.26.1
Post employment benefits - Analysis of fair value of plan assets (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Jun. 30, 2025
Disclosure of fair value of plan assets [line items]    
Equities(1) $ 1,249 $ 1,553
Property 493 653
Hedge funds 4 10
Interest rate and inflation swaps (58) (232)
Cash, short-term and other investments 468 367
Total bid value of assets 8,057 8,533
Fixed-interest government    
Disclosure of fair value of plan assets [line items]    
Bonds 553 390
Inflation-linked government    
Disclosure of fair value of plan assets [line items]    
Bonds 1,499 2,183
Investment grade corporate    
Disclosure of fair value of plan assets [line items]    
Bonds 2,307 1,959
Non-investment grade    
Disclosure of fair value of plan assets [line items]    
Bonds 1,097 1,071
Loan securities    
Disclosure of fair value of plan assets [line items]    
Bonds 311 449
Liability Driven Investment (LDI)    
Disclosure of fair value of plan assets [line items]    
Bonds 134 130
Quoted    
Disclosure of fair value of plan assets [line items]    
Equities(1) 67 89
Property 6 0
Hedge funds 0 0
Interest rate and inflation swaps 11 12
Cash, short-term and other investments 127 67
Total bid value of assets 1,638 1,939
Quoted | Fixed-interest government    
Disclosure of fair value of plan assets [line items]    
Bonds 380 280
Quoted | Inflation-linked government    
Disclosure of fair value of plan assets [line items]    
Bonds 984 1,447
Quoted | Investment grade corporate    
Disclosure of fair value of plan assets [line items]    
Bonds 30 19
Quoted | Non-investment grade    
Disclosure of fair value of plan assets [line items]    
Bonds 30 7
Quoted | Loan securities    
Disclosure of fair value of plan assets [line items]    
Bonds 3 18
Quoted | Liability Driven Investment (LDI)    
Disclosure of fair value of plan assets [line items]    
Bonds 0 0
Unquoted    
Disclosure of fair value of plan assets [line items]    
Equities(1) 1,182 1,464
Property 487 653
Hedge funds 4 10
Interest rate and inflation swaps (69) (244)
Cash, short-term and other investments 341 300
Total bid value of assets 6,419 6,594
Unquoted | Fixed-interest government    
Disclosure of fair value of plan assets [line items]    
Bonds 173 110
Unquoted | Inflation-linked government    
Disclosure of fair value of plan assets [line items]    
Bonds 515 736
Unquoted | Investment grade corporate    
Disclosure of fair value of plan assets [line items]    
Bonds 2,277 1,940
Unquoted | Non-investment grade    
Disclosure of fair value of plan assets [line items]    
Bonds 1,067 1,064
Unquoted | Loan securities    
Disclosure of fair value of plan assets [line items]    
Bonds 308 431
Unquoted | Liability Driven Investment (LDI)    
Disclosure of fair value of plan assets [line items]    
Bonds 134 130
United Kingdom    
Disclosure of fair value of plan assets [line items]    
Pooled investment 1,590 1,431
United Kingdom | Quoted    
Disclosure of fair value of plan assets [line items]    
Equities(1) 0 0
Property 6 0
Hedge funds 0 0
Interest rate and inflation swaps 0 1
Cash, short-term and other investments 91 49
Total bid value of assets 1,418 1,744
United Kingdom | Quoted | Fixed-interest government    
Disclosure of fair value of plan assets [line items]    
Bonds 308 224
United Kingdom | Quoted | Inflation-linked government    
Disclosure of fair value of plan assets [line items]    
Bonds 983 1,447
United Kingdom | Quoted | Investment grade corporate    
Disclosure of fair value of plan assets [line items]    
Bonds 0 0
United Kingdom | Quoted | Non-investment grade    
Disclosure of fair value of plan assets [line items]    
Bonds 27 5
United Kingdom | Quoted | Loan securities    
Disclosure of fair value of plan assets [line items]    
Bonds 3 18
United Kingdom | Quoted | Liability Driven Investment (LDI)    
Disclosure of fair value of plan assets [line items]    
Bonds 0 0
United Kingdom | Unquoted    
Disclosure of fair value of plan assets [line items]    
Equities(1) 750 961
Property 429 595
Hedge funds 0 0
Interest rate and inflation swaps (150) (264)
Cash, short-term and other investments 190 163
Total bid value of assets 3,853 3,896
United Kingdom | Unquoted | Fixed-interest government    
Disclosure of fair value of plan assets [line items]    
Bonds 0 22
United Kingdom | Unquoted | Inflation-linked government    
Disclosure of fair value of plan assets [line items]    
Bonds 505 618
United Kingdom | Unquoted | Investment grade corporate    
Disclosure of fair value of plan assets [line items]    
Bonds 1,196 846
United Kingdom | Unquoted | Non-investment grade    
Disclosure of fair value of plan assets [line items]    
Bonds 707 640
United Kingdom | Unquoted | Loan securities    
Disclosure of fair value of plan assets [line items]    
Bonds 226 315
United Kingdom | Unquoted | Liability Driven Investment (LDI)    
Disclosure of fair value of plan assets [line items]    
Bonds 0 0
Ireland    
Disclosure of fair value of plan assets [line items]    
Pooled investment 1,102 1,147
Ireland | Quoted    
Disclosure of fair value of plan assets [line items]    
Equities(1) 0 0
Property 0 0
Hedge funds 0 0
Interest rate and inflation swaps 11 11
Cash, short-term and other investments 36 18
Total bid value of assets 66 31
Ireland | Quoted | Fixed-interest government    
Disclosure of fair value of plan assets [line items]    
Bonds 16 0
Ireland | Quoted | Inflation-linked government    
Disclosure of fair value of plan assets [line items]    
Bonds 1 0
Ireland | Quoted | Investment grade corporate    
Disclosure of fair value of plan assets [line items]    
Bonds 0 0
Ireland | Quoted | Non-investment grade    
Disclosure of fair value of plan assets [line items]    
Bonds 2 2
Ireland | Quoted | Loan securities    
Disclosure of fair value of plan assets [line items]    
Bonds 0 0
Ireland | Quoted | Liability Driven Investment (LDI)    
Disclosure of fair value of plan assets [line items]    
Bonds 0 0
Ireland | Unquoted    
Disclosure of fair value of plan assets [line items]    
Equities(1) 292 366
Property 58 58
Hedge funds 0 0
Interest rate and inflation swaps 81 20
Cash, short-term and other investments 110 97
Total bid value of assets 1,872 2,026
Ireland | Unquoted | Fixed-interest government    
Disclosure of fair value of plan assets [line items]    
Bonds 105 80
Ireland | Unquoted | Inflation-linked government    
Disclosure of fair value of plan assets [line items]    
Bonds 9 117
Ireland | Unquoted | Investment grade corporate    
Disclosure of fair value of plan assets [line items]    
Bonds 641 667
Ireland | Unquoted | Non-investment grade    
Disclosure of fair value of plan assets [line items]    
Bonds 360 375
Ireland | Unquoted | Loan securities    
Disclosure of fair value of plan assets [line items]    
Bonds 82 116
Ireland | Unquoted | Liability Driven Investment (LDI)    
Disclosure of fair value of plan assets [line items]    
Bonds 134 130
United States and other | Quoted    
Disclosure of fair value of plan assets [line items]    
Equities(1) 67 89
Property 0 0
Hedge funds 0 0
Interest rate and inflation swaps 0 0
Cash, short-term and other investments 0 0
Total bid value of assets 154 164
United States and other | Quoted | Fixed-interest government    
Disclosure of fair value of plan assets [line items]    
Bonds 56 56
United States and other | Quoted | Inflation-linked government    
Disclosure of fair value of plan assets [line items]    
Bonds 0 0
United States and other | Quoted | Investment grade corporate    
Disclosure of fair value of plan assets [line items]    
Bonds 30 19
United States and other | Quoted | Non-investment grade    
Disclosure of fair value of plan assets [line items]    
Bonds 1 0
United States and other | Quoted | Loan securities    
Disclosure of fair value of plan assets [line items]    
Bonds 0 0
United States and other | Quoted | Liability Driven Investment (LDI)    
Disclosure of fair value of plan assets [line items]    
Bonds 0 0
United States and other | Unquoted    
Disclosure of fair value of plan assets [line items]    
Equities(1) 140 137
Property 0 0
Hedge funds 4 10
Interest rate and inflation swaps 0 0
Cash, short-term and other investments 41 40
Total bid value of assets 694 672
United States and other | Unquoted | Fixed-interest government    
Disclosure of fair value of plan assets [line items]    
Bonds 68 8
United States and other | Unquoted | Inflation-linked government    
Disclosure of fair value of plan assets [line items]    
Bonds 1 1
United States and other | Unquoted | Investment grade corporate    
Disclosure of fair value of plan assets [line items]    
Bonds 440 427
United States and other | Unquoted | Non-investment grade    
Disclosure of fair value of plan assets [line items]    
Bonds 0 49
United States and other | Unquoted | Loan securities    
Disclosure of fair value of plan assets [line items]    
Bonds 0 0
United States and other | Unquoted | Liability Driven Investment (LDI)    
Disclosure of fair value of plan assets [line items]    
Bonds 0 0
United States    
Disclosure of fair value of plan assets [line items]    
Pooled investment $ 625 $ 598