Accounts receivable - Allowance for Credit Losses (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Aug. 04, 2018	Aug. 04, 2018	Jul. 29, 2017	Feb. 03, 2018
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance		$ (113.5)
Reversal of allowance on receivables previously held for sale		160.4	$ (20.7)
Ending receivable balance evaluated for impairment			1,792.5	$ 762.9
Sterling Jewelers customer in-house finance receivables, net	$ 6.5	6.5	664.5	692.5
Consumer Portfolio Segment
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance		(113.5)	(138.7)
Charge-offs, net		56.3	103.9
Recoveries		4.2	17.8
Provision		(54.6)	(118.0)
Reversal of allowance on receivables previously held for sale		107.6	20.7
Ending balance	0.0	0.0	(114.3)
Ending receivable balance evaluated for impairment	0.0	0.0	736.9
Sterling Jewelers customer in-house finance receivables, net	0.0	0.0	656.6	682.9
Sterling Jewelers \| Consumer Portfolio Segment
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Reversal of allowance on receivables previously held for sale	(19.4)	(160.4)
Sterling Jewelers customer in-house finance receivables, net	$ 0.0	$ 0.0	$ 622.6	$ 649.4

Financing Receivable, Allowance for Credit Losses, Net of Reversal

No definition available.

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- Definition

Financing Receivable, Allowance for Credit Losses, Reversal

+ References

No definition available.

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- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

A valuation allowance for financing receivables that are expected to be uncollectible.

+ References

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- Definition

Amount of recovery of financing receivables doubtful of collection that were previously charged off.

+ References

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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- Definition

Amount of direct write-downs of financing receivables charged against the allowance.

+ References

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- Definition

The balance of financing receivables that were collectively evaluated for impairment.

+ References

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- Definition

Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.11)
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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