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.

No definition available.

+ Details

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

- Definition

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(iv)(01)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(iv)(01)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(ii)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(ii)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of actual investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanSponsorLocationAxis=country_US
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_DefinedBenefitPlanEquitySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=sna_DebtSecuritiesAndCashAndCashEquivalentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=sna_RealEstateAndOtherRealAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_HedgeFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanSponsorLocationAxis=us-gaap_ForeignPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=sna_InsuranceContractsAndHedgeFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Pension Plans - Summary of Target Allocation and Weighted-Average Asset Allocation by Asset Category and Fair Value of Plan Assets (Detail) - USD ($) $ in Millions	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1,455.5	$ 1,215.6	$ 1,305.0
United States
Defined Benefit Plan Disclosure [Line Items]
Target allocation	100.00%
Actual weighted-average asset allocation	100.00%	100.00%
Fair value of plan assets	$ 1,260.5	$ 1,049.0
United States \| Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1,260.5	$ 1,049.0
United States \| Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation	51.00%
Actual weighted-average asset allocation	51.00%	49.00%
United States \| Debt securities and cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Target allocation	37.00%
Actual weighted-average asset allocation	40.00%	40.00%
United States \| Real estate and other real assets
Defined Benefit Plan Disclosure [Line Items]
Target allocation	2.00%
Actual weighted-average asset allocation	1.00%	1.00%
United States \| Real estate and other real assets \| Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 8.8	$ 11.9
United States \| Hedge funds
Defined Benefit Plan Disclosure [Line Items]
Target allocation	10.00%
Actual weighted-average asset allocation	8.00%	10.00%
United States \| Hedge funds \| Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 107.8	$ 104.5
Foreign Pension Plans \| Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Target allocation	100.00%
Actual weighted-average asset allocation	100.00%	100.00%
Fair value of plan assets	$ 195.0	$ 166.6
Foreign Pension Plans \| Equity securities \| Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Target allocation	46.00%
Actual weighted-average asset allocation	46.00%	35.00%
Foreign Pension Plans \| Debt securities and cash and cash equivalents \| Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Target allocation	40.00%
Actual weighted-average asset allocation	40.00%	42.00%
Foreign Pension Plans \| Hedge funds \| Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 14.3
Foreign Pension Plans \| Insurance contracts and hedge funds \| Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Target allocation	14.00%
Actual weighted-average asset allocation	14.00%	23.00%