v3.26.1
Post-retirement benefit obligations - Sensitivity Analysis (Details) - ZAR (R)
R in Millions
Jun. 30, 2026
Jun. 30, 2025
Sensitivity analysis    
Cost inflation as premium over CPI 2.00%  
South Africa | Healthcare | Healthcare cost inflation    
Sensitivity analysis    
Increase in actuarial assumption (as a percent) 1.00% 1.00%
Decrease in actuarial assumption (as a percent) 1.00% 1.00%
Increase (decrease) in net obligation due to increase in actuarial assumption R 518 R 434
Increase (decrease) in net obligation due to decrease in actuarial assumption R (450) R (377)
South Africa | Healthcare | Discount rate    
Sensitivity analysis    
Increase in actuarial assumption (as a percent) 1.00% 1.00%
Decrease in actuarial assumption (as a percent) 1.00% 1.00%
Increase (decrease) in net obligation due to increase in actuarial assumption R (433) R (360)
Increase (decrease) in net obligation due to decrease in actuarial assumption R 505 R 419
United States of America | Healthcare | Healthcare cost inflation    
Sensitivity analysis    
Increase in actuarial assumption (as a percent) 1.00% 1.00%
Decrease in actuarial assumption (as a percent) 1.00% 1.00%
United States of America | Healthcare | Discount rate    
Sensitivity analysis    
Increase in actuarial assumption (as a percent) 1.00% 1.00%
Decrease in actuarial assumption (as a percent) 1.00% 1.00%
Increase (decrease) in net obligation due to increase in actuarial assumption R (7) R (21)
Increase (decrease) in net obligation due to decrease in actuarial assumption R 9 R 25