Debt - Foreign exchange gains and losses (Details) - Secured debt - Euro Term Loan - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Debt Instrument
(Loss) gain recognized in statement of operations	$ (6.9)	$ (8.1)	$ (2.0)	$ 5.3
Loss recognized in OCI	(2.1)	(1.4)	(0.6)	(0.7)
Total (loss) gain	$ (9.0)	$ (9.5)	$ (2.6)	$ 4.6

Amount before tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 10
-Section 45
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=120253306&loc=d3e28129-110885

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 30
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=118261656&loc=d3e32022-110900

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 45
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 45
-Paragraph 10A
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 35
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-URI http://asc.fasb.org/extlink&oid=121605123&loc=d3e30304-110892

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Balance Type:	credit
Period Type:	duration