v3.26.3
Segment reporting - Summarized segment assets and liabilities and additions (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Dec. 31, 2025
Disclosure of operating segments [line items]          
Segment assets $ 4,115.3   $ 4,115.3   $ 4,489.6
Total liabilities 4,285.6   4,285.6   $ 4,579.4
Additions of property, plant and equipment, right of use assets and intangible assets 53.5 $ 96.0 163.7 $ 236.9  
Operating segments          
Disclosure of operating segments [line items]          
Additions of property, plant and equipment, right of use assets and intangible assets 53.9 96.0 164.1 236.5  
Unallocated items          
Disclosure of operating segments [line items]          
Additions of property, plant and equipment, right of use assets and intangible assets (0.4)   (0.4) 0.4  
Nigeria | Operating segments          
Disclosure of operating segments [line items]          
Additions of property, plant and equipment, right of use assets and intangible assets 33.7 41.7 76.2 60.3  
SSA | Operating segments          
Disclosure of operating segments [line items]          
Additions of property, plant and equipment, right of use assets and intangible assets 16.5 31.3 33.1 69.4  
Latam | Operating segments          
Disclosure of operating segments [line items]          
Additions of property, plant and equipment, right of use assets and intangible assets $ 3.7 $ 23.0 $ 54.8 $ 106.8