Segments - Net Sales by Segment (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Segment Reporting Information [Line Items]
Total revenues	$ 808.9	$ 1,035.4	$ 1,747.0	$ 2,042.7
Operating earnings	148.7	250.5	344.5	500.0
Interest expense	(13.4)	(12.4)	(24.8)	(24.9)
Other income (expense) – net	2.0	2.1	3.5	3.6
Earnings before income taxes and equity earnings	137.3	240.2	323.2	478.7
Commercial & Industrial Group
Segment Reporting Information [Line Items]
Total revenues	261.9	335.0	561.8	657.5
Snap-on Tools Group
Segment Reporting Information [Line Items]
Total revenues	323.3	405.8	699.2	816.0
Repair Systems & Information Group
Segment Reporting Information [Line Items]
Total revenues	245.0	348.9	559.6	676.8
Financial Services
Segment Reporting Information [Line Items]
Total revenues	84.6	84.1	170.5	169.7
Operating Segments
Segment Reporting Information [Line Items]
Total revenues	830.2	1,089.7	1,820.6	2,150.3
Operating earnings	169.5	269.4	383.8	528.8
Operating Segments | Commercial & Industrial Group
Segment Reporting Information [Line Items]
Total revenues	261.9	335.0	561.8	657.5
Operating earnings	22.9	48.9	54.4	95.4
Operating Segments | Snap-on Tools Group
Segment Reporting Information [Line Items]
Total revenues	323.3	405.8	699.2	816.0
Operating earnings	38.4	71.3	87.0	138.5
Operating Segments | Repair Systems & Information Group
Segment Reporting Information [Line Items]
Total revenues	245.0	348.9	559.6	676.8
Operating earnings	50.6	88.6	127.9	172.2
Operating Segments | Financial Services
Segment Reporting Information [Line Items]
Operating earnings	57.6	60.6	114.5	122.7
Intersegment eliminations
Segment Reporting Information [Line Items]
Total revenues	(105.9)	(138.4)	(244.1)	(277.3)
Corporate
Segment Reporting Information [Line Items]
Operating earnings	(20.8)	(18.9)	(39.3)	(28.8)
Excluding Financial Services
Segment Reporting Information [Line Items]
Total revenues	724.3	951.3	1,576.5	1,873.0
Operating earnings	91.1	189.9	230.0	377.3
Excluding Financial Services | Commercial & Industrial Group
Segment Reporting Information [Line Items]
Total revenues	204.5	263.0	431.5	512.5
Excluding Financial Services | Snap-on Tools Group
Segment Reporting Information [Line Items]
Total revenues	323.3	405.8	699.2	816.0
Excluding Financial Services | Repair Systems & Information Group
Segment Reporting Information [Line Items]
Total revenues	196.5	282.5	445.8	544.5
Excluding Financial Services | Financial Services
Segment Reporting Information [Line Items]
Total revenues	0.0	0.0	0.0	0.0
Excluding Financial Services | Operating Segments
Segment Reporting Information [Line Items]
Total revenues	724.3	951.3	1,576.5	1,873.0
Excluding Financial Services | Operating Segments | Commercial & Industrial Group
Segment Reporting Information [Line Items]
Total revenues	261.9	335.0	561.8	657.5
Excluding Financial Services | Operating Segments | Snap-on Tools Group
Segment Reporting Information [Line Items]
Total revenues	323.3	405.8	699.2	816.0
Excluding Financial Services | Operating Segments | Repair Systems & Information Group
Segment Reporting Information [Line Items]
Total revenues	245.0	348.9	559.6	676.8
Excluding Financial Services | Operating Segments | Financial Services
Segment Reporting Information [Line Items]
Total revenues	0.0	0.0	0.0	0.0
Excluding Financial Services | Intersegment eliminations
Segment Reporting Information [Line Items]
Total revenues	(105.9)	(138.4)	(244.1)	(277.3)
Excluding Financial Services | Intersegment eliminations | Commercial & Industrial Group
Segment Reporting Information [Line Items]
Total revenues	57.4	72.0	130.3	145.0
Excluding Financial Services | Intersegment eliminations | Snap-on Tools Group
Segment Reporting Information [Line Items]
Total revenues	0.0	0.0	0.0	0.0
Excluding Financial Services | Intersegment eliminations | Repair Systems & Information Group
Segment Reporting Information [Line Items]
Total revenues	48.5	66.4	113.8	132.3
Excluding Financial Services | Intersegment eliminations | Financial Services
Segment Reporting Information [Line Items]
Total revenues	0.0	0.0	0.0	0.0
Financial Service
Segment Reporting Information [Line Items]
Total revenues	84.6	84.1	170.5	169.7
Operating earnings	57.6	60.6	114.5	122.7
Financial Service | Commercial & Industrial Group
Segment Reporting Information [Line Items]
Total revenues	0.0	0.0	0.0	0.0
Financial Service | Snap-on Tools Group
Segment Reporting Information [Line Items]
Total revenues	0.0	0.0	0.0	0.0
Financial Service | Repair Systems & Information Group
Segment Reporting Information [Line Items]
Total revenues	0.0	0.0	0.0	0.0
Financial Service | Financial Services
Segment Reporting Information [Line Items]
Total revenues	84.6	84.1	170.5	169.7
Financial Service | Intersegment eliminations
Segment Reporting Information [Line Items]
Total revenues	$ 0.0	$ 0.0	$ 0.0	$ 0.0