Schedule II - Valuation and Qualifying Accounts and Reserves - (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017
Doubtful accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 2.2	$ 1.9	$ 3.2
Charged to costs and expenses	4.1	3.3	3.8
Charged to other accounts	0.0	0.0	0.0
Deductions	4.7	3.0	5.1
Balance at end of period	1.6	2.2	1.9
Sales returns
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	15.0	9.6	8.3
Charged to costs and expenses	12.6	7.5	2.5
Charged to other accounts	0.0	0.0	0.0
Deductions	10.1	2.1	1.2
Balance at end of period	17.5	15.0	9.6
Allowance for inventory liquidation and obsolescence
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	75.0	65.4	59.2
Charged to costs and expenses	31.9	28.9	19.2
Charged to other accounts	0.0	0.0	0.0
Deductions	25.4	19.3	13.0
Balance at end of period	81.5	75.0	65.4
Allowance for inventory shrinkage
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	0.7	1.0	1.2
Charged to costs and expenses	1.7	1.1	0.5
Charged to other accounts	0.0	0.0	0.0
Deductions	1.1	1.4	0.7
Balance at end of period	1.3	0.7	1.0
Deferred tax valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	9.6	24.1	19.5
Charged to costs and expenses	0.2	2.3	5.0
Charged to other accounts	0.0	0.0	0.0
Deductions	1.3	16.8	0.4
Balance at end of period	$ 8.5	$ 9.6	$ 24.1