Cost-reduction actions - Liabilities and Expected Future Payments Related to Work-Force Reduction Actions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Restructuring Reserve [Roll Forward]
Additional provisions	$ 54.9	$ 23.2	$ 95.5
Work-Force Reductions
Restructuring Reserve [Roll Forward]
Balance at beginning of period	16.3	55.9	49.8
Additional provisions	7.1	12.3	39.0
Payments	(11.5)	(38.5)	(21.5)
Changes in estimates	0.4	(11.9)	(13.5)
Translation adjustments	(0.6)	(1.5)	2.1
Balance at end of period	11.7	16.3	55.9
Expected future payments on balance at December 31, 2022:
In 2023	11.7
Work-Force Reductions | U.S.
Restructuring Reserve [Roll Forward]
Balance at beginning of period	5.7	13.1	5.2
Additional provisions	3.6	7.9	13.8
Payments	(4.1)	(13.2)	(3.2)
Changes in estimates	(1.0)	(2.1)	(2.7)
Translation adjustments	0.0	0.0	0.0
Balance at end of period	4.2	5.7	13.1
Expected future payments on balance at December 31, 2022:
In 2023	4.2
Work-Force Reductions | International
Restructuring Reserve [Roll Forward]
Balance at beginning of period	10.6	42.8	44.6
Additional provisions	3.5	4.4	25.2
Payments	(7.4)	(25.3)	(18.3)
Changes in estimates	1.4	(9.8)	(10.8)
Translation adjustments	(0.6)	(1.5)	2.1
Balance at end of period	7.5	$ 10.6	$ 42.8
Expected future payments on balance at December 31, 2022:
In 2023	$ 7.5