Shareholders' equity - Reconciliation of basic to diluted weighted average common shares outstanding (Details) - shares shares in Thousands	3 Months Ended	9 Months Ended
Oct. 01, 2023	Sep. 25, 2022	Oct. 01, 2023	Sep. 25, 2022
Equity [Abstract]
Basic (in shares)	46,992	46,906	46,974	46,894
Dilutive effect of share-based awards (in shares)	307	357	330	443
Diluted (in shares)	47,299	47,263	47,304	47,337

No definition available.

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- Definition

Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
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-Topic 260
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
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-URI https://asc.fasb.org//1943274/2147482689/260-10-45-28A

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- Definition

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482662/260-10-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
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- Definition

Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482662/260-10-50-1

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