Segments - Net Sales by Segment (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 01, 2017	Jul. 02, 2016	Jul. 01, 2017	Jul. 02, 2016
Segment Reporting Information [Line Items]
Net sales	$ 921.4	$ 872.3	$ 1,808.5	$ 1,706.5
Financial services revenue	77.7	69.3	154.5	135.6
Total revenues	999.1	941.6	1,963.0	1,842.1
Operating earnings	238.3	215.9	460.3	418.3
Interest expense	(13.0)	(12.9)	(25.7)	(26.0)
Other income (expense) - net	(1.9)	1.2	(3.6)	0.5
Earnings before income taxes and equity earnings	223.4	204.2	431.0	392.8
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	1,061.9	997.6	2,088.8	1,965.9
Operating earnings	259.8	239.6	502.9	463.4
Operating Segments [Member] | Commercial & Industrial Group [Member]
Segment Reporting Information [Line Items]
Net sales	310.0	285.7	608.7	572.7
Operating earnings	42.7	39.3	84.3	80.4
Operating Segments [Member] | Snap-on Tools Group [Member]
Segment Reporting Information [Line Items]
Net sales	413.8	416.7	823.2	819.2
Operating earnings	80.6	76.3	150.9	143.0
Operating Segments [Member] | Repair Systems & Information Group [Member]
Segment Reporting Information [Line Items]
Net sales	338.1	295.2	656.9	574.0
Operating earnings	81.9	74.5	160.6	143.5
Operating Segments [Member] | Financial Services [Member]
Segment Reporting Information [Line Items]
Operating earnings	54.6	49.5	107.1	96.5
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Net sales	(140.5)	(125.3)	(280.3)	(259.4)
Corporate [Member]
Segment Reporting Information [Line Items]
Operating earnings	$ (21.5)	$ (23.7)	$ (42.6)	$ (45.1)