SELECTED QUARTERLY FINANCIAL DATA - Summary of Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended																12 Months Ended
	Jan. 03, 2020	[1]	Sep. 27, 2019	[2]	Jun. 28, 2019	[3]	Mar. 29, 2019	[4]	Dec. 28, 2018	[5]	Sep. 28, 2018	[6]	Jun. 29, 2018	[7]	Mar. 30, 2018	[8]	Jan. 03, 2020	Dec. 28, 2018	Dec. 29, 2017
Quarterly Operating Results Unaudited [Line Items]
Net sales	$ 2,252.3		$ 2,222.2		$ 2,262.6		$ 2,108.5		$ 2,119.1		$ 2,179.0		$ 2,137.9		$ 1,964.2		$ 8,845.6	$ 8,400.2	$ 7,927.4
Cost of goods sold	1,791.8		1,775.8		1,812.6		1,689.6		1,689.1		1,754.9		1,718.8		1,579.4		7,069.8	6,742.2	6,356.4
Operating income	85.4		101.8		105.7		74.6		87.3		89.5		71.3		61.6		367.5	309.7	312.9
Income before income taxes	69.7		82.1		85.6		56.0		59.9		68.6		49.0		45.7		293.4	223.2	237.6
Net income	$ 101.0		$ 59.3		$ 63.5		$ 39.1		$ 41.8		$ 47.6		$ 34.8		$ 32.1		$ 262.9	$ 156.3	$ 109.0
Income per share:
Basic	$ 2.95		$ 1.74		$ 1.86		$ 1.15		$ 1.23		$ 1.41		$ 1.03		$ 0.95		$ 7.71	$ 4.62	$ 3.24
Diluted	$ 2.93		$ 1.73		$ 1.86		$ 1.14		$ 1.22		$ 1.40		$ 1.02		$ 0.94		$ 7.67	$ 4.58	$ 3.21

[1] In the fourth quarter of 2019, "Operating income" includes $8.6 million of intangible asset amortization and $12.8 million of merger costs. "Net income" includes a $45.9 million tax benefit related to the reversal of deferred income tax valuation allowances, partially offset by $0.8 million of tax expense related to prior year tax positions.

[2] In the third quarter of 2019, "Operating income" includes $8.8 million of intangible asset amortization.

[3] In the second quarter of 2019, "Operating income" includes $8.8 million of intangible asset amortization.

[4] In the first quarter of 2019, "Operating income" includes $8.8 million of intangible asset amortization and a reversal of acquisition and integration costs of $0.3 million.

[5] In the fourth quarter of 2018, "Operating income" includes $8.7 million of intangible asset amortization and $0.2 million of U.K. facility relocation costs. "Income before income taxes" includes a $4.6 million loss on extinguishment of debt.

[6] In the third quarter of 2018, "Operating income" includes $9.6 million of intangible asset amortization, a restructuring charge of $0.2 million, $0.3 million of acquisition and integration costs and $0.2 million of U.K. facility relocation costs.

[7] In the second quarter of 2018, "Operating income" includes $9.7 million of intangible asset amortization, a restructuring charge of $9.2 million, $2.3 million of acquisition and integration costs, $2.6 million of CEO retirement agreement expense and $0.4 million of U.K. facility relocation costs.

[8] In the first quarter of 2018, "Operating income" includes $9.3 million of intangible asset amortization, $0.3 million of acquisition and integration costs and $0.2 million of U.K. facility relocation costs.