Warranty reserve - Warranty reserve (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2015	Nov. 01, 2014	Oct. 31, 2015	Nov. 01, 2014
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at beginning of period	$ 43.1	$ 48.1	$ 44.9	$ 19.1
Standard Product Warranty Accrual, Additions from Business Acquisition	0.0	0.0	0.0	28.8
Product Warranty Expense	3.0	1.2	7.9	5.2
Product Warranty Accrual, Payments	(3.6)	(2.6)	(10.3)	(6.4)
Balance at end of period	$ 42.5	$ 46.7	$ 42.5	$ 46.7