Segments - Assets by Segment (Detail) - USD ($) $ in Millions	Sep. 26, 2020	Dec. 28, 2019
Segment Reporting Information [Line Items]
Assets	$ 6,267.6	$ 5,693.5
Operating Segments
Segment Reporting Information [Line Items]
Assets	5,438.9	5,452.1
Operating Segments | Commercial & Industrial Group
Segment Reporting Information [Line Items]
Assets	1,124.2	1,138.8
Operating Segments | Snap-on Tools Group
Segment Reporting Information [Line Items]
Assets	796.7	827.4
Operating Segments | Repair Systems & Information Group
Segment Reporting Information [Line Items]
Assets	1,366.8	1,381.9
Operating Segments | Financial Services
Segment Reporting Information [Line Items]
Assets	2,151.2	2,104.0
Corporate
Segment Reporting Information [Line Items]
Assets	884.8	303.1
Elimination of intersegment receivables
Segment Reporting Information [Line Items]
Assets	$ (56.1)	$ (61.7)