Acquisitions - Allocation of Purchase Price to Fair Value of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Millions	1 Months Ended	4 Months Ended
	Mar. 31, 2018	Feb. 28, 2019	Sep. 28, 2019	Dec. 29, 2018	Oct. 31, 2018	Mar. 01, 2018
Business Acquisition [Line Items]
Goodwill			$ 1,152.2	$ 1,143.9
Mountain Valley Acquisition
Business Acquisition [Line Items]
Cash and cash equivalents		$ 8.2			$ 8.2
Accounts receivable		4.2			4.2
Inventory		2.3			2.3
Prepaid expenses and other current assets		0.2			0.2
Goodwill		16.0			20.5
Intangible assets		28.4			25.8
Accounts payable and accrued liabilities		(20.8)			(19.3)
Total		80.0			80.4
Measurement Period Adjustments
Property, plant and equipment, adjustment		3.0
Goodwill, adjustment		(4.5)
Intangible assets, adjustment		2.6
Accounts payable and accrued liabilities, adjustment		(1.5)
Total, adjustment		(0.4)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		$ 41.5			$ 38.5
Crystal Rock Acquisition
Business Acquisition [Line Items]
Cash and cash equivalents	$ 1.6					$ 1.6
Accounts receivable	6.4					6.5
Inventory	2.2					2.3
Prepaid expenses and other current assets	2.2					1.2
Goodwill	14.2					16.7
Intangible assets	12.6					13.3
Other assets	0.1					0.8
Short-term borrowings	(4.1)					(4.1)
Current maturities of long-term debt	(1.6)					(1.6)
Accounts payable and accrued liabilities	(6.7)					(5.2)
Long-term debt	(10.4)					(10.4)
Deferred tax liabilities	3.0					6.5
Other long-term liabilities	(0.9)					(2.5)
Total	21.5					21.5
Measurement Period Adjustments
Accounts receivable, adjustment	(0.1)
Inventory, adjustment	(0.1)
Prepaid expenses and other current assets, adjustment	1.0
Property, plant and equipment, adjustment	0.5
Goodwill, adjustment	2.5
Intangible assets, adjustment	0.7
Other assets, adjustment	(0.7)
Accounts payable and accrued liabilities, adjustment	1.5
Deferred tax liabilities, adjustment	3.5
Other long-term liabilities, adjustment	1.6
Total, adjustment	0.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	$ 8.9					$ 9.4