Accumulated other comprehensive income (loss) - Changes in Accumulated OCI by Component and Reclassifications Out of Accumulated OCI (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	May 02, 2015	May 03, 2014
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Balance at January 31, 2015	$ (236.6)
Other comprehensive income (OCI) before reclassifications	1.5
Amounts reclassified from accumulated OCI to earnings	0.8	4.8
Total other comprehensive income (loss)	2.3	14.7
Balance at May 2, 2015	(234.3)	(163.8)
Foreign currency translation
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Balance at January 31, 2015	(197.6)
Other comprehensive income (OCI) before reclassifications	7.5
Amounts reclassified from accumulated OCI to earnings	0
Total other comprehensive income (loss)	7.5
Balance at May 2, 2015	(190.1)
Losses on available-for-sale securities, net
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Balance at January 31, 2015	0
Other comprehensive income (OCI) before reclassifications	(0.1)
Amounts reclassified from accumulated OCI to earnings	0
Total other comprehensive income (loss)	(0.1)
Balance at May 2, 2015	(0.1)
Gains (losses) on cash flow hedges
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Balance at January 31, 2015	4.4
Other comprehensive income (OCI) before reclassifications	(5.9)
Amounts reclassified from accumulated OCI to earnings	0.5
Total other comprehensive income (loss)	(5.4)
Balance at May 2, 2015	(1.0)
Pension Plan | Actuarial gains (losses)
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Balance at January 31, 2015	(56.7)
Other comprehensive income (OCI) before reclassifications	0
Amounts reclassified from accumulated OCI to earnings	0.7
Total other comprehensive income (loss)	0.7
Balance at May 2, 2015	(56.0)
Pension Plan | Prior service credit (cost)
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Balance at January 31, 2015	13.3
Other comprehensive income (OCI) before reclassifications	0
Amounts reclassified from accumulated OCI to earnings	(0.4)
Total other comprehensive income (loss)	(0.4)
Balance at May 2, 2015	$ 12.9