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Segments - Net Sales by Segment (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 28, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 29, 2018	Sep. 29, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Segment Reporting Information [Line Items]
Net sales									$ 4,067.7	$ 4,070.4	$ 4,000.3
Operating earnings									962.3	956.1	882.1
Interest expense									(49.0)	(50.4)	(52.4)
Other income (expense) – net									8.8	4.2	(7.8)
Earnings before income taxes and equity earnings									922.1	909.9	821.9
Commercial & Industrial Group
Segment Reporting Information [Line Items]
Net sales									1,345.7	1,343.3
Snap-on Tools Group
Segment Reporting Information [Line Items]
Net sales									1,612.9	1,613.8
Repair Systems & Information Group
Segment Reporting Information [Line Items]
Net sales									1,334.5	1,334.4
Financial Services
Segment Reporting Information [Line Items]
Net sales									337.7	329.7
Operating Segments
Segment Reporting Information [Line Items]
Operating earnings									1,023.1	1,036.2	1,014.0
Operating Segments \| Commercial & Industrial Group
Segment Reporting Information [Line Items]
Operating earnings									188.7	199.3	186.5
Operating Segments \| Snap-on Tools Group
Segment Reporting Information [Line Items]
Operating earnings									245.8	264.2	274.7
Operating Segments \| Repair Systems & Information Group
Segment Reporting Information [Line Items]
Operating earnings									342.7	342.6	335.3
Operating Segments \| Financial Services
Segment Reporting Information [Line Items]
Operating earnings									245.9	230.1	217.5
Intersegment eliminations
Segment Reporting Information [Line Items]
Net sales									(563.1)	(550.8)
Corporate
Segment Reporting Information [Line Items]
Operating earnings									(60.8)	(80.1)	(131.9)
Product And Services, Excluding Financial Services
Segment Reporting Information [Line Items]
Net sales	$ 955.2	$ 901.8	$ 951.3	$ 921.7	$ 952.5	$ 898.1	$ 954.6	$ 935.5	3,730.0	3,740.7	3,686.9
Operating earnings									716.4	726.0	664.6
Product And Services, Excluding Financial Services \| Commercial & Industrial Group
Segment Reporting Information [Line Items]
Net sales									1,038.2	1,051.6
Product And Services, Excluding Financial Services \| Snap-on Tools Group
Segment Reporting Information [Line Items]
Net sales									1,612.9	1,613.8
Product And Services, Excluding Financial Services \| Repair Systems & Information Group
Segment Reporting Information [Line Items]
Net sales									1,078.9	1,075.3
Product And Services, Excluding Financial Services \| Financial Services
Segment Reporting Information [Line Items]
Net sales									0.0	0.0
Product And Services, Excluding Financial Services \| Operating Segments
Segment Reporting Information [Line Items]
Net sales									4,293.1	4,291.5	4,237.3
Product And Services, Excluding Financial Services \| Operating Segments \| Commercial & Industrial Group
Segment Reporting Information [Line Items]
Net sales									1,345.7	1,343.3	1,265.0
Product And Services, Excluding Financial Services \| Operating Segments \| Snap-on Tools Group
Segment Reporting Information [Line Items]
Net sales									1,612.9	1,613.8	1,625.1
Product And Services, Excluding Financial Services \| Operating Segments \| Repair Systems & Information Group
Segment Reporting Information [Line Items]
Net sales									1,334.5	1,334.4	1,347.2
Product And Services, Excluding Financial Services \| Operating Segments \| Financial Services
Segment Reporting Information [Line Items]
Net sales									0.0	0.0
Product And Services, Excluding Financial Services \| Intersegment eliminations
Segment Reporting Information [Line Items]
Net sales									(563.1)	(550.8)	(550.4)
Product And Services, Excluding Financial Services \| Intersegment eliminations \| Commercial & Industrial Group
Segment Reporting Information [Line Items]
Net sales									307.5	291.7
Product And Services, Excluding Financial Services \| Intersegment eliminations \| Snap-on Tools Group
Segment Reporting Information [Line Items]
Net sales									0.0	0.0
Product And Services, Excluding Financial Services \| Intersegment eliminations \| Repair Systems & Information Group
Segment Reporting Information [Line Items]
Net sales									255.6	259.1
Product And Services, Excluding Financial Services \| Intersegment eliminations \| Financial Services
Segment Reporting Information [Line Items]
Net sales									0.0	0.0
Financial Service
Segment Reporting Information [Line Items]
Net sales	$ 83.9	$ 84.1	$ 84.1	$ 85.6	$ 82.7	$ 82.0	$ 82.0	$ 83.0	337.7	329.7	313.4
Operating earnings									245.9	230.1	$ 217.5
Financial Service \| Commercial & Industrial Group
Segment Reporting Information [Line Items]
Net sales									0.0	0.0
Financial Service \| Snap-on Tools Group
Segment Reporting Information [Line Items]
Net sales									0.0	0.0
Financial Service \| Repair Systems & Information Group
Segment Reporting Information [Line Items]
Net sales									0.0	0.0
Financial Service \| Financial Services
Segment Reporting Information [Line Items]
Net sales									$ 337.7	$ 329.7