Earnings Per Share, Basic And Diluted (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 28, 2012	Jul. 30, 2011	Jul. 28, 2012	Jul. 30, 2011
Shareholders Equity and Earnings Per Share [Line Items]
Net income	$ 70.7	$ 66.3	$ 153.2	$ 141.7
Basic weighted average number of shares in issue	82.6	86.3	84.1	86.1
Dilutive effect of share options	0.4	0.8	0.6	0.8
Diluted weighted average number of shares in issue	83.0	87.1	84.7	86.9
Earnings per share - basic	$ 0.86	$ 0.77	$ 1.82	$ 1.64
Earnings per share - diluted	$ 0.85	$ 0.76	$ 1.81	$ 1.63