Goodwill and Intangible Assets - Purchased Intangible Assets (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 25, 2020	Dec. 27, 2019
Finite Lived Intangible Assets [Line Items]
Definite lives intangible assets, accumulated amortization	$ (81.6)	$ (61.8)
Definite lives intangible assets, net carrying amount	151.5
Intangible Assets, gross carrying value	242.1	242.1
Intangible Assets, net carrying value	160.5	180.3
Customer Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Definite lives intangible assets, gross carrying amount	119.4	119.4
Definite lives intangible assets, accumulated amortization	(50.6)	(39.8)
Definite lives intangible assets, net carrying amount	$ 68.8	79.6
Customer Relationships [Member] | Minimum [Member]
Finite Lived Intangible Assets [Line Items]
Total intangible assets, useful life	6 years
Customer Relationships [Member] | Maximum [Member]
Finite Lived Intangible Assets [Line Items]
Total intangible assets, useful life	10 years
Trade Name [Member]
Finite Lived Intangible Assets [Line Items]
Definite lives intangible assets, gross carrying amount	$ 27.0	27.0
Definite lives intangible assets, accumulated amortization	(11.7)	(8.1)
Definite lives intangible assets, net carrying amount	$ 15.3	18.9
Trade Name [Member] | Minimum [Member]
Finite Lived Intangible Assets [Line Items]
Total intangible assets, useful life	4 years
Trade Name [Member] | Maximum [Member]
Finite Lived Intangible Assets [Line Items]
Total intangible assets, useful life	6 years
Intellectual Properties/Know-How [Member]
Finite Lived Intangible Assets [Line Items]
Definite lives intangible assets, gross carrying amount	$ 13.9	13.9
Definite lives intangible assets, accumulated amortization	(9.8)	(8.4)
Definite lives intangible assets, net carrying amount	$ 4.1	5.5
Intellectual Properties/Know-How [Member] | Minimum [Member]
Finite Lived Intangible Assets [Line Items]
Total intangible assets, useful life	7 years
Intellectual Properties/Know-How [Member] | Maximum [Member]
Finite Lived Intangible Assets [Line Items]
Total intangible assets, useful life	12 years
Recipes [Member]
Finite Lived Intangible Assets [Line Items]
Total intangible assets, useful life	20 years
Definite lives intangible assets, gross carrying amount	$ 73.2	73.2
Definite lives intangible assets, accumulated amortization	(8.5)	(4.9)
Definite lives intangible assets, net carrying amount	$ 64.7	68.3
StandardOperatingProceduresMember
Finite Lived Intangible Assets [Line Items]
Total intangible assets, useful life	20 years
Definite lives intangible assets, gross carrying amount	$ 8.6	8.6
Definite lives intangible assets, accumulated amortization	(1.0)	(0.6)
Definite lives intangible assets, net carrying amount	$ 7.6	$ 8.0