Acquired Intangible Assets and Goodwill - Schedule of Goodwill (Details) $ in Millions	6 Months Ended
Jul. 04, 2026 USD ($)
Goodwill [Roll Forward]
Beginning balance	$ 383.9
Ending balance	428.2
Kiwi Acquisition
Goodwill [Roll Forward]
Kiwi II Acquisition	44.3
Janus North America
Goodwill [Roll Forward]
Beginning balance	371.8
Ending balance	416.1
Janus North America \| Kiwi Acquisition
Goodwill [Roll Forward]
Kiwi II Acquisition	44.3
Janus International
Goodwill [Roll Forward]
Beginning balance	12.1
Ending balance	12.1
Janus International \| Kiwi Acquisition
Goodwill [Roll Forward]
Kiwi II Acquisition	$ 0.0

Amount, after accumulated impairment loss, of asset representing future economic benefit arising from other asset acquired in business combination or from joint venture formation or both, that is not individually identified and separately recognized.

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+ Details