Revenue recognition - Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
Feb. 02, 2019	Feb. 03, 2018
Movement in Deferred Revenue [Roll Forward]
ESP deferred revenue, beginning of period	$ 916.1	$ 905.6
Plans sold	395.0	409.3
Revenue recognized	(383.5)	(398.8)
ESP deferred revenue, end of period	$ 927.6	$ 916.1

Amount of increase in the standard and extended product warranty accrual from warranties issued.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph ((c)(3))
-URI http://asc.fasb.org/extlink&oid=68068213&loc=d3e12565-110249

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