Supplementary balance sheet information (Details) - USD ($) $ in Millions	Sep. 29, 2024	Dec. 31, 2023
Accounts and other receivables
Trade receivables	$ 55.9	$ 52.3
Prepayments and accrued income	7.9	5.7
Derivative financial instruments	0.9	0.4
Total accounts and other receivables	75.2	59.9
Inventories
Raw materials and supplies	34.7	34.7
Work-in-process	28.1	34.8
Finished goods	30.7	26.4
Total inventories	93.5	95.9
Other current assets
Income tax receivable	1.5	1.5
Total other current assets	1.5	1.5
Property, plant and equipment, net
Total property, plant and equipment	311.2	299.5
Accumulated depreciation and impairment	(245.5)	(235.7)
Total property, plant and equipment, net	65.7	63.8
Current maturities of long-term debt and short-term borrowings
Overdrafts	3.7	4.6
Total current maturities of long-term debt and short-term borrowings	3.7	4.6
Other current liabilities
Restructuring provision	3.2	3.3
Short term provision	0.1	0.1
Derivative financial instruments	0.0	0.0
Operating lease liability	4.6	4.7
Advance payments	2.0	0.8
Total other current liabilities	$ 9.9	$ 8.9
Operating lease, liability, current, statement of financial position [extensible enumeration]	Total other current liabilities	Total other current liabilities
Other non-current liabilities
Contingent liabilities	$ 1.8	$ 1.6
Operating lease liability	11.5	15.0
Other non-current liabilities	0.1	0.2
Total other non-current liabilities	$ 13.4	$ 16.8
Operating lease, liability, noncurrent, statement of financial position [extensible enumeration]	Total other non-current liabilities	Total other non-current liabilities
Related party
Accounts and other receivables
Other receivables	$ 0.1	$ 0.1
Nonrelated party
Accounts and other receivables
Other receivables	10.4	1.4
Land, buildings and leasehold improvements
Property, plant and equipment, net
Total property, plant and equipment	53.7	51.0
Machinery and equipment
Property, plant and equipment, net
Total property, plant and equipment	244.8	234.9
Construction in progress
Property, plant and equipment, net
Total property, plant and equipment	$ 12.7	$ 13.6