Goodwill and other intangible assets - Schedule of Other intangibles (Details) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Finite-lived
Gross value	$ 5,851.4	$ 5,923.4
Accumulated amortization and impairment	3,011.4	2,821.9
Carrying value	2,840.0	3,101.5
Indefinite-lived	92.3	92.3
Total	2,932.3	3,193.8
Accumulated asset impairment charge	106.4	106.4
Customer relationships
Finite-lived
Gross value	4,852.0	4,915.0
Accumulated amortization and impairment	2,329.6	2,172.7
Carrying value	2,522.4	2,742.3
Accumulated asset impairment charge	65.9	65.9
Trade names
Finite-lived
Gross value	362.5	366.8
Accumulated amortization and impairment	283.5	272.9
Carrying value	79.0	93.9
Other
Finite-lived
Gross value	636.9	641.6
Accumulated amortization and impairment	398.3	376.3
Carrying value	238.6	265.3
Accumulated asset impairment charge	$ 40.5	$ 40.5