Segments - Net Sales by Segment (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 28, 2019	Sep. 29, 2018	Sep. 28, 2019	Sep. 29, 2018
Segment Reporting Information [Line Items]
Total revenues	$ 985.9	$ 980.1	$ 3,028.6	$ 3,035.2
Operating earnings	228.7	232.4	728.7	717.9
Interest expense	(12.0)	(12.4)	(36.9)	(38.0)
Other income (expense) – net	2.8	(1.0)	6.4	1.2
Earnings before income taxes and equity earnings	219.5	219.0	698.2	681.1
Commercial & Industrial Group
Segment Reporting Information [Line Items]
Total revenues	335.3	330.2	992.8	999.6
Snap-on Tools Group
Segment Reporting Information [Line Items]
Total revenues	385.2	389.8	1,201.2	1,206.4
Repair Systems & Information Group
Segment Reporting Information [Line Items]
Total revenues	322.7	314.4	999.5	994.5
Financial Services
Segment Reporting Information [Line Items]
Total revenues	84.1	82.0	253.8	247.0
Operating Segments
Segment Reporting Information [Line Items]
Total revenues	1,043.2	1,034.4	3,193.5	3,200.5
Operating earnings	245.6	252.3	774.4	784.9
Operating Segments \| Commercial & Industrial Group
Segment Reporting Information [Line Items]
Total revenues	335.3	330.2	992.8	999.6
Operating earnings	48.3	53.0	143.7	148.5
Operating Segments \| Snap-on Tools Group
Segment Reporting Information [Line Items]
Total revenues	385.2	389.8	1,201.2	1,206.4
Operating earnings	53.0	59.3	191.5	207.2
Operating Segments \| Repair Systems & Information Group
Segment Reporting Information [Line Items]
Total revenues	322.7	314.4	999.5	994.5
Operating earnings	83.3	80.7	255.5	255.2
Operating Segments \| Financial Services
Segment Reporting Information [Line Items]
Operating earnings	61.0	59.3	183.7	174.0
Intersegment eliminations
Segment Reporting Information [Line Items]
Total revenues	(141.4)	(136.3)	(418.7)	(412.3)
Corporate
Segment Reporting Information [Line Items]
Operating earnings	(16.9)	(19.9)	(45.7)	(67.0)
Excluding Financial Services
Segment Reporting Information [Line Items]
Total revenues	901.8	898.1	2,774.8	2,788.2
Operating earnings	167.7	173.1	545.0	543.9
Excluding Financial Services \| Commercial & Industrial Group
Segment Reporting Information [Line Items]
Total revenues	257.0	255.7	769.5	781.6
Excluding Financial Services \| Snap-on Tools Group
Segment Reporting Information [Line Items]
Total revenues	385.2	389.8	1,201.2	1,206.4
Excluding Financial Services \| Repair Systems & Information Group
Segment Reporting Information [Line Items]
Total revenues	259.6	252.6	804.1	800.2
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	901.8	898.1	2,774.8	2,788.2
Excluding Financial Services \| Operating Segments \| Commercial & Industrial Group
Segment Reporting Information [Line Items]
Total revenues	335.3	330.2	992.8	999.6
Excluding Financial Services \| Operating Segments \| Snap-on Tools Group
Segment Reporting Information [Line Items]
Total revenues	385.2	389.8	1,201.2	1,206.4
Excluding Financial Services \| Operating Segments \| Repair Systems & Information Group
Segment Reporting Information [Line Items]
Total revenues	322.7	314.4	999.5	994.5
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	(141.4)	(136.3)	(418.7)	(412.3)
Excluding Financial Services \| Intersegment eliminations \| Commercial & Industrial Group
Segment Reporting Information [Line Items]
Total revenues	78.3	74.5	223.3	218.0
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	63.1	61.8	195.4	194.3
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	84.1	82.0	253.8	247.0
Operating earnings	61.0	59.3	183.7	174.0
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	84.1	82.0	253.8	247.0
Financial Service \| Intersegment eliminations
Segment Reporting Information [Line Items]
Total revenues	$ 0.0	$ 0.0	$ 0.0	$ 0.0

Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h)(1)(i))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of the cost of borrowed funds accounted for as interest expense.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (210.5-03(11))
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.9)
-URI http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260

+ Details

Name:	us-gaap_InterestExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The net result for the period of deducting operating expenses from operating revenues.

+ References

No definition available.

+ Details

Name:	us-gaap_OperatingIncomeLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of income (expense) related to nonoperating activities, classified as other.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.9)
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

+ Details

Name:	us-gaap_OtherNonoperatingIncomeExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8933-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(1))
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

+ Details

Name:	us-gaap_Revenues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_SegmentReportingInformationLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=sna_CommercialAndIndustrialGroupMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=sna_ToolsGroupMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=sna_RepairSystemsAndInformationGroupMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=sna_FinancialServicesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidationItemsAxis=us-gaap_OperatingSegmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidationItemsAxis=us-gaap_IntersegmentEliminationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidationItemsAxis=us-gaap_CorporateNonSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=sna_ProductAndServicesExcludingFinancialServicesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=us-gaap_FinancialServiceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: