Goodwill and Purchased Intangible Assets - Changes in the Carrying Amount of Goodwill (Details) $ in Thousands	9 Months Ended
Sep. 25, 2021 USD ($)
Goodwill Roll Forward
Beginning balance	$ 306,632
Goodwill from Inspectrology acquisition (Note 2)	7,259
Ending balance	$ 313,891

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
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