Carrying value as of the balance sheet date of obligations incurred through that date and payable for estimated claims under standard and extended warranty protection rights granted to customers. For classified balance sheets, represents the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 25
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=68070138&loc=d3e11281-110244

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=68068213&loc=d3e12524-110249

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_ProductWarrantyAccrualClassifiedCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Warranty reserve (Details) - USD ($) $ in Millions	Jul. 29, 2017	Apr. 29, 2017	Jan. 28, 2017	Jul. 30, 2016	Apr. 30, 2016	Jan. 30, 2016
Product Warranty Liability [Line Items]
Product warranty accrual	$ 39.3	$ 39.2	$ 40.0	$ 40.4	$ 41.3	$ 41.9
Current liabilities
Product Warranty Liability [Line Items]
Current liabilities	12.2		13.0	12.5
Non-current liabilities
Product Warranty Liability [Line Items]
Non-current liabilities	$ 27.1		$ 27.0	$ 27.9