Segmental Information - Financial information by reportable segment (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 29, 2019	Sep. 30, 2018	Sep. 29, 2019	Sep. 30, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Net sales	$ 107.1	$ 129.1	$ 344.0	$ 377.0
Adjusted EBITDA	16.7	23.0	55.4	63.6
Depreciation and amortization	3.6	4.7	11.3	14.5
Restructuring charges	2.6	1.1	24.3	2.1
Total assets	402.4		402.4		$ 408.8
Capital expenditures	0.8	4.2	11.1	8.0
Gas Cylinders
Segment Reporting Information [Line Items]
Net sales	54.2	62.2	170.7	181.9
Adjusted EBITDA	6.3	6.3	17.9	17.3
Depreciation and amortization	1.3	1.9	4.1	5.8
Restructuring charges	2.3	0.0	19.5	0.1
Elektron
Segment Reporting Information [Line Items]
Net sales	52.9	66.9	173.3	195.1
Adjusted EBITDA	10.4	16.7	37.5	46.3
Depreciation and amortization	2.3	2.8	7.2	8.7
Restructuring charges	0.3	1.1	4.8	2.0
Operating Segments \| Gas Cylinders
Segment Reporting Information [Line Items]
Total assets	161.4		161.4		156.3
Capital expenditures	0.5	0.8	2.9	1.5
Operating Segments \| Elektron
Segment Reporting Information [Line Items]
Total assets	203.2		203.2		218.2
Capital expenditures	0.3	3.3	8.2	6.4
Other
Segment Reporting Information [Line Items]
Total assets	37.8		37.8		$ 34.3
Capital expenditures	$ 0.0	$ 0.1	$ 0.0	$ 0.1

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Capital Expenditure, Cash And Noncash

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Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

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Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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