Accumulated other comprehensive income (loss) - Changes in Accumulated OCI by Component and Reclassifications Out of Accumulated OCI (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Aug. 01, 2015	Aug. 02, 2014	Aug. 01, 2015	Aug. 02, 2014
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Balance at January 31, 2015			$ (236.6)
Other comprehensive income (OCI) before reclassifications			(8.9)
Amounts reclassified from AOCI to earnings	$ 1.0	$ 3.4	1.8	$ 8.2
Total other comprehensive income (loss)	(9.4)	0.8	(7.1)	15.5
Balance at May 2, 2015	(243.7)	$ (163.0)	(243.7)	$ (163.0)
Foreign currency translation
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Balance at January 31, 2015			(197.6)
Other comprehensive income (OCI) before reclassifications			2.8
Amounts reclassified from AOCI to earnings			0.0
Total other comprehensive income (loss)			2.8
Balance at May 2, 2015	(194.8)		(194.8)
Losses on available-for-sale securities, net
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Balance at January 31, 2015			0.0
Other comprehensive income (OCI) before reclassifications			(0.3)
Amounts reclassified from AOCI to earnings			0.0
Total other comprehensive income (loss)			(0.3)
Balance at May 2, 2015	(0.3)		(0.3)
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			(11.4)
Amounts reclassified from AOCI to earnings			1.3
Total other comprehensive income (loss)			(10.1)
Balance at May 2, 2015	(5.7)		(5.7)
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			0.0
Amounts reclassified from AOCI to earnings			1.4
Total other comprehensive income (loss)			1.4
Balance at May 2, 2015	(55.3)		(55.3)
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			0.0
Amounts reclassified from AOCI to earnings			(0.9)
Total other comprehensive income (loss)			(0.9)
Balance at May 2, 2015	$ 12.4		$ 12.4