v3.26.1
Segment reporting - Reconciliation of information on reportable segments to the amounts reported in the financial statements (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Geographical information          
Revenues from external customers $ 428.6 $ 388.2 [1] $ 844.0 $ 780.3 [1]  
Finance costs (105.5) (79.4) [1] (210.1) (172.6) [1]  
Finance income 48.5 31.2 [1] 159.0 49.6 [1]  
Income before taxation 25.8 101.0 [1] 143.0 192.0 [1]  
Segment assets 4,360.0   4,360.0   $ 4,489.6
Total liabilities 4,542.6   4,542.6   $ 4,579.4
Expense from long-term employee benefits due to changes in expected vesting and settlement amounts in connection with merger agreement 39.9 0.0 57.4 0.0  
Costs related to internal reorganization 0.0 1.2 0.0 1.7  
Expenses related to strategic initiatives and operating systems 15.8 2.8 22.8 4.5  
Impairment of assets held for sale (45.4)   (75.4) 0.0  
Discontinued operations          
Geographical information          
Revenues from external customers 42.4 45.1 94.2 92.6  
Finance costs (11.5) (34.9) (25.8) (56.1)  
Finance income 4.0 4.4 13.9 6.5  
Gain on disposal of subsidiary 20.0   20.0    
Income before taxation (1.7) (33.3) 1.1 (55.2)  
Impairment loss 45.4   75.4    
Aggregate continuing and discontinuing operations          
Geographical information          
Segment Adjusted EBITDA 270.0 277.3 567.8 563.7  
Unallocated corporate expenses (24.7) (28.8) (53.8) (62.7)  
Finance costs (117.0) (114.3) (235.9) (228.7)  
Depreciation and amortization (56.2) (89.0) (112.0) (178.4)  
Share-based payment expense (16.8) (8.5) (40.7) (14.0)  
Other costs (56.8) (5.5) (81.2) (8.6)  
Net impairment of property, plant and equipment, intangible assets excluding goodwill and related prepaid land rent (47.5) (1.7) (80.4) (3.6)  
Business combination costs (6.3) (0.3) (15.5) (1.2)  
Insurance claims 0.1 0.2 0.1 0.3  
Net gain/(loss) on disposal of property, plant and equipment and right-of-use assets 1.9 2.2 3.4 1.0  
Net impairment loss/(reversal) of withholding tax receivables 4.9 0.5 (0.6) 12.9  
Finance income 52.5 35.6 172.9 56.1  
Gain on disposal of subsidiary 20.0   20.0    
Cost of sales          
Geographical information          
Net impairment of property, plant and equipment, intangible assets excluding goodwill and related prepaid land rent (1.5) (1.0) (3.8) (1.7)  
Nigeria          
Geographical information          
Revenues from external customers 298.3 260.4 583.2 531.7  
Nigeria | Aggregate continuing and discontinuing operations          
Geographical information          
Revenues from external customers 298.3 260.4 583.2 531.7  
Segment Adjusted EBITDA 166.5 170.7 349.0 349.8  
SSA          
Geographical information          
Revenues from external customers 130.3 127.8 260.8 248.6  
SSA | Aggregate continuing and discontinuing operations          
Geographical information          
Revenues from external customers 130.3 127.8 260.8 248.6  
Segment Adjusted EBITDA 70.8 73.1 148.4 144.8  
Latam | Discontinued operations          
Geographical information          
Revenues from external customers 42.4 45.1 94.2 92.6  
Latam | Aggregate continuing and discontinuing operations          
Geographical information          
Revenues from external customers 42.4 45.1 94.2 92.6  
Segment Adjusted EBITDA $ 32.7 $ 33.5 $ 70.4 $ 69.1  
[1] The results for the three and six months ended June 30, 2025 have been re-presented to reflect that the results of the Latam segment is now reported as a discontinued operation. See note 21.1 for more information