Segments - Net Sales by Segment (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 26, 2020	Sep. 28, 2019	Sep. 26, 2020	Sep. 28, 2019
Segment Reporting Information [Line Items]
Total revenues	$ 1,027.4	$ 985.9	$ 2,774.4	$ 3,028.6
Operating earnings	251.3	228.7	595.8	728.7
Interest expense	(13.8)	(12.0)	(38.6)	(36.9)
Other income (expense) – net	2.8	2.8	6.3	6.4
Earnings before income taxes and equity earnings	240.3	219.5	563.5	698.2
Commercial & Industrial Group
Segment Reporting Information [Line Items]
Total revenues	308.4	335.3	870.2	992.8
Snap-on Tools Group
Segment Reporting Information [Line Items]
Total revenues	449.8	385.2	1,149.0	1,201.2
Repair Systems & Information Group
Segment Reporting Information [Line Items]
Total revenues	317.5	322.7	877.1	999.5
Financial Services
Segment Reporting Information [Line Items]
Total revenues	85.8	84.1	256.3	253.8
Operating Segments
Segment Reporting Information [Line Items]
Total revenues	1,075.7	1,043.2	2,896.3	3,193.5
Operating earnings	275.9	245.6	659.7	774.4
Operating Segments | Commercial & Industrial Group
Segment Reporting Information [Line Items]
Total revenues	308.4	335.3	870.2	992.8
Operating earnings	43.1	48.3	97.5	143.7
Operating Segments | Snap-on Tools Group
Segment Reporting Information [Line Items]
Total revenues	449.8	385.2	1,149.0	1,201.2
Operating earnings	87.1	53.0	174.1	191.5
Operating Segments | Repair Systems & Information Group
Segment Reporting Information [Line Items]
Total revenues	317.5	322.7	877.1	999.5
Operating earnings	80.1	83.3	208.0	255.5
Operating Segments | Financial Services
Segment Reporting Information [Line Items]
Operating earnings	65.6	61.0	180.1	183.7
Intersegment eliminations
Segment Reporting Information [Line Items]
Total revenues	(134.1)	(141.4)	(378.2)	(418.7)
Corporate
Segment Reporting Information [Line Items]
Operating earnings	(24.6)	(16.9)	(63.9)	(45.7)
Excluding Financial Services
Segment Reporting Information [Line Items]
Total revenues	941.6	901.8	2,518.1	2,774.8
Operating earnings	185.7	167.7	415.7	545.0
Excluding Financial Services | Commercial & Industrial Group
Segment Reporting Information [Line Items]
Total revenues	235.7	257.0	667.2	769.5
Excluding Financial Services | Snap-on Tools Group
Segment Reporting Information [Line Items]
Total revenues	449.8	385.2	1,149.0	1,201.2
Excluding Financial Services | Repair Systems & Information Group
Segment Reporting Information [Line Items]
Total revenues	256.1	259.6	701.9	804.1
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	941.6	901.8	2,518.1	2,774.8
Excluding Financial Services | Operating Segments | Commercial & Industrial Group
Segment Reporting Information [Line Items]
Total revenues	308.4	335.3	870.2	992.8
Excluding Financial Services | Operating Segments | Snap-on Tools Group
Segment Reporting Information [Line Items]
Total revenues	449.8	385.2	1,149.0	1,201.2
Excluding Financial Services | Operating Segments | Repair Systems & Information Group
Segment Reporting Information [Line Items]
Total revenues	317.5	322.7	877.1	999.5
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	(134.1)	(141.4)	(378.2)	(418.7)
Excluding Financial Services | Intersegment eliminations | Commercial & Industrial Group
Segment Reporting Information [Line Items]
Total revenues	72.7	78.3	203.0	223.3
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	61.4	63.1	175.2	195.4
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	85.8	84.1	256.3	253.8
Operating earnings	65.6	61.0	180.1	183.7
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	85.8	84.1	256.3	253.8
Financial Service | Intersegment eliminations
Segment Reporting Information [Line Items]
Total revenues	$ 0.0	$ 0.0	$ 0.0	$ 0.0