Revenue recognition - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
May 02, 2020	May 04, 2019
Extended Service Plans and Lifetime Warranty Agreements
Disaggregation of Revenue [Line Items]
Capitalized contract cost, amortization	$ 4.3	$ 7.5
North America \| Extended Service Plans and Lifetime Warranty Agreements
Disaggregation of Revenue [Line Items]
Revenue, performance obligation, description of timing	17 years
North America \| Jewelry Replacement Plan
Disaggregation of Revenue [Line Items]
Revenue, performance obligation, description of timing	three years

Amount of amortization expense for asset recognized from cost incurred to obtain or fulfill contract with customer.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 340
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=68051541&loc=SL49131252-203054

+ Details

Name:	us-gaap_CapitalizedContractCostAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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_DisaggregationOfRevenueLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of timing for satisfying performance obligation in contract with customer. Includes, but is not limited to, as services are rendered, and upon shipment, delivery or completion of service.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130554-203045

+ Details

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

- Details

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

- Details

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

- Details

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