Accumulated other comprehensive income (loss) - Changes in Accumulated OCI by Component and Reclassifications Out of Accumulated OCI (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2015	Nov. 01, 2014	Oct. 31, 2015	Nov. 01, 2014
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Balance at January 31, 2015			$ (236.6)
Other comprehensive income (loss) (OCI) before reclassifications			(12.1)
Amounts reclassified from AOCI to earnings	$ 1.1	$ 2.0	2.9	$ 10.2
Other comprehensive loss	(2.1)	(20.9)	(9.2)	(5.4)
Balance at October 31, 2015	(245.8)	$ (183.9)	(245.8)	$ (183.9)
Foreign currency translation
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Balance at January 31, 2015			(197.6)
Other comprehensive income (loss) (OCI) before reclassifications			(1.4)
Amounts reclassified from AOCI to earnings			0.0
Other comprehensive loss			(1.4)
Balance at October 31, 2015	(199.0)		(199.0)
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 (loss) (OCI) before reclassifications			(0.4)
Amounts reclassified from AOCI to earnings			0.0
Other comprehensive loss			(0.4)
Balance at October 31, 2015	(0.4)		(0.4)
Gains (losses) on cash flow hedges
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Balance at January 31, 2015			4.4
Other comprehensive income (loss) (OCI) before reclassifications			(10.3)
Amounts reclassified from AOCI to earnings			2.2
Other comprehensive loss			(8.1)
Balance at October 31, 2015	(3.7)		(3.7)
Pension Plan | Actuarial losses
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Balance at January 31, 2015			(56.7)
Other comprehensive income (loss) (OCI) before reclassifications			0.0
Amounts reclassified from AOCI to earnings			2.1
Other comprehensive loss			2.1
Balance at October 31, 2015	(54.6)		(54.6)
Pension Plan | Prior service credits
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Balance at January 31, 2015			13.3
Other comprehensive income (loss) (OCI) before reclassifications			0.0
Amounts reclassified from AOCI to earnings			(1.4)
Other comprehensive loss			(1.4)
Balance at October 31, 2015	$ 11.9		$ 11.9