Segments - Net Sales by Segment (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Segment Reporting Information [Line Items]
Net sales	$ 903.8	$ 834.1	$ 2,712.3	$ 2,540.6
Financial services revenue	79.0	71.6	233.5	207.2
Total revenues	982.8	905.7	2,945.8	2,747.8
Operating earnings	209.1	208.2	669.4	626.5
Interest expense	(13.1)	(13.1)	(38.8)	(39.1)
Other income (expense) - net	(2.1)	(0.8)	(5.7)	(0.3)
Earnings before income taxes and equity earnings	193.9	194.3	624.9	587.1
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	1,040.8	972.6	3,129.6	2,938.5
Operating earnings	245.8	230.7	748.7	694.1
Operating Segments [Member] \| Commercial & Industrial Group [Member]
Segment Reporting Information [Line Items]
Net sales	314.6	289.3	923.3	862.0
Operating earnings	50.1	43.7	134.4	124.1
Operating Segments [Member] \| Snap-on Tools Group [Member]
Segment Reporting Information [Line Items]
Net sales	392.7	397.2	1,215.9	1,216.4
Operating earnings	56.3	64.6	207.2	207.6
Operating Segments [Member] \| Repair Systems & Information Group [Member]
Segment Reporting Information [Line Items]
Net sales	333.5	286.1	990.4	860.1
Operating earnings	83.4	71.8	244.0	215.3
Operating Segments [Member] \| Financial Services [Member]
Segment Reporting Information [Line Items]
Operating earnings	56.0	50.6	163.1	147.1
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales	(137.0)	(138.5)	(417.3)	(397.9)
Corporate [Member]
Segment Reporting Information [Line Items]
Operating earnings	$ (36.7)	$ (22.5)	$ (79.3)	$ (67.6)

The aggregate financial services revenue and operating interest income earned during the reporting period.

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Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

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