Common Shares, Treasury Shares, Reserves and Dividends - Dividends (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
Jan. 30, 2016	Oct. 31, 2015	Aug. 01, 2015	May. 02, 2015	Jan. 31, 2015	Nov. 01, 2014	Aug. 02, 2014	May. 03, 2014	Feb. 01, 2014	Nov. 02, 2013	Aug. 03, 2013	May. 04, 2013	Jan. 30, 2016	Jan. 31, 2015	Feb. 01, 2014
Equity [Abstract]
Cash dividend per share (usd per share)	$ 0.22	$ 0.22	$ 0.22	$ 0.22	$ 0.18	$ 0.18	$ 0.18	$ 0.18	$ 0.15	$ 0.15	$ 0.15		$ 0.88	$ 0.72	$ 0.6
Cash dividend per share (usd per share)													$ 0.88	$ 0.72	$ 0.60
Dividends payable	$ 17.5				$ 14.4								$ 17.5	$ 14.4
Total dividends	$ 17.5	$ 17.5	$ 17.6	$ 17.6	$ 14.4	$ 14.5	$ 14.4	$ 14.4	$ 12.0	$ 12.0	$ 12.1	$ 12.1	$ 70.2	$ 57.7	$ 48.2

Aggregate dividends paid during the period for each share of common stock outstanding.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

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Aggregate dividends declared during the period for each share of common stock outstanding.

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Amount of paid and unpaid common stock dividends declared with the form of settlement in cash.

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Carrying value as of the balance sheet date of dividends declared but unpaid on equity securities issued by the entity and outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.15(5))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.15(5))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 15
-Subparagraph a
-Article 7

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