Goodwill and Intangible Assets - Goodwill (Details) - USD ($) $ in Millions	Sep. 26, 2021	Dec. 27, 2020
Goodwill [Line Items]
Gross value	$ 737.0	$ 737.2
Less accumulated impairment	253.3	253.3
Net	483.7	483.9
KGS
Goodwill [Line Items]
Gross value	609.6	609.6
Less accumulated impairment	239.5	239.5
Net	370.1	370.1
US
Goodwill [Line Items]
Gross value	127.4	127.6
Less accumulated impairment	13.8	13.8
Net	$ 113.6	$ 113.8

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.

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Amount before 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.

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