Goodwill and Other Intangible Assets - Changes in Carrying Amount of Goodwill by Segment (Detail) $ in Millions	9 Months Ended
	Sep. 26, 2020 USD ($)
Goodwill [Roll Forward]
Balance as of December 28, 2019	$ 913.8
Currency translation	16.0
Acquisitions and related adjustments	8.7
Balance as of June 27, 2020	938.5
Commercial & Industrial Group
Goodwill [Roll Forward]
Balance as of December 28, 2019	286.2
Currency translation	11.3
Acquisitions and related adjustments	0.0
Balance as of June 27, 2020	297.5
Snap-on Tools Group
Goodwill [Roll Forward]
Balance as of December 28, 2019	12.5
Currency translation	0.0
Acquisitions and related adjustments	0.0
Balance as of June 27, 2020	12.5
Repair Systems & Information Group
Goodwill [Roll Forward]
Balance as of December 28, 2019	615.1
Currency translation	4.7
Acquisitions and related adjustments	8.7
Balance as of June 27, 2020	$ 628.5