Segments - Assets by Segment (Detail) - USD ($) $ in Millions	Jun. 29, 2019	Dec. 29, 2018
Segment Reporting Information [Line Items]
Assets	$ 5,545.4	$ 5,373.1
Operating Segments
Segment Reporting Information [Line Items]
Assets	5,347.7	5,186.5
Operating Segments | Commercial & Industrial Group
Segment Reporting Information [Line Items]
Assets	1,136.4	1,087.9
Operating Segments | Snap-on Tools Group
Segment Reporting Information [Line Items]
Assets	794.3	752.7
Operating Segments | Repair Systems & Information Group
Segment Reporting Information [Line Items]
Assets	1,349.6	1,306.3
Operating Segments | Financial Services
Segment Reporting Information [Line Items]
Assets	2,067.4	2,039.6
Corporate
Segment Reporting Information [Line Items]
Assets	262.4	249.2
Elimination of intersegment receivables
Segment Reporting Information [Line Items]
Assets	$ (64.7)	$ (62.6)