Segment information - Summary of Activity by Segment (Details) - USD ($) $ in Millions	3 Months Ended
Apr. 29, 2017	Apr. 30, 2016	Jan. 28, 2017
Segment Reporting Information [Line Items]
Sales	$ 1,403.4	$ 1,578.9
Operating income (loss)	115.3	212.0
Total assets	6,465.2	6,427.7	$ 6,597.8
Sterling Jewelers
Segment Reporting Information [Line Items]
Sales	871.0	980.4
Operating income (loss)	129.5	198.3
Total assets	3,891.6	3,756.6	4,015.4
Zale Jewelry
Segment Reporting Information [Line Items]
Sales	333.7	381.4
Operating income (loss)	2.1	18.3
Total assets	1,926.8	1,974.9	1,940.7
Piercing Pagoda
Segment Reporting Information [Line Items]
Sales	69.7	69.0
Operating income (loss)	3.2	7.8
Total assets	143.4	139.1	141.6
UK Jewelry
Segment Reporting Information [Line Items]
Sales	122.5	144.0
Operating income (loss)	(2.5)	1.3
Total assets	394.3	447.8	372.6
Other
Segment Reporting Information [Line Items]
Sales	6.5	4.1
Operating income (loss)	(17.0)	(13.7)
Total assets	$ 109.1	$ 109.3	$ 127.5

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(12))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(11))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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