Segments - Net Sales by Segment (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017
Segment Reporting Information [Line Items]
Net sales	$ 935.5	$ 887.1
Financial services revenue	83.0	76.8
Total revenues	1,018.5	963.9
Operating earnings	234.6	222.7
Interest expense	(13.6)	(12.7)
Other income (expense) – net	2.8	(2.4)
Earnings before income taxes and equity earnings	223.8	207.6
Commercial & Industrial Group
Segment Reporting Information [Line Items]
Financial services revenue	0.0
Total revenues	331.6
Snap-on Tools Group
Segment Reporting Information [Line Items]
Financial services revenue	0.0
Total revenues	404.7
Repair Systems & Information Group
Segment Reporting Information [Line Items]
Financial services revenue	0.0
Total revenues	337.0
Financial Services
Segment Reporting Information [Line Items]
Financial services revenue	83.0
Total revenues	83.0
Operating Segments
Segment Reporting Information [Line Items]
Net sales	1,073.3	1,026.9
Operating earnings	258.1	243.8
Operating Segments | Commercial & Industrial Group
Segment Reporting Information [Line Items]
Net sales	331.6	298.7
Operating earnings	46.5	41.9
Operating Segments | Snap-on Tools Group
Segment Reporting Information [Line Items]
Net sales	404.7	409.4
Operating earnings	68.9	70.3
Operating Segments | Repair Systems & Information Group
Segment Reporting Information [Line Items]
Net sales	337.0	318.8
Operating earnings	85.8	79.1
Operating Segments | Financial Services
Segment Reporting Information [Line Items]
Operating earnings	56.9	52.5
Intersegment eliminations
Segment Reporting Information [Line Items]
Net sales	(137.8)	(139.8)
Total revenues	(137.8)
Corporate
Segment Reporting Information [Line Items]
Operating earnings	$ (23.5)	$ (21.1)