Schedule II - Valuation and Qualifying Accounts and Reserves - (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Doubtful accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 1.6	$ 2.2	$ 1.9
Charged to costs and expenses	3.7	4.1	3.3
Charged to other accounts	0.0	0.0	0.0
Deductions	3.4	4.7	3.0
Balance at end of period	1.9	1.6	2.2
Sales returns
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	17.5	15.0	9.6
Charged to costs and expenses	4.1	12.6	7.5
Charged to other accounts	0.0	0.0	0.0
Deductions	4.4	10.1	2.1
Balance at end of period	17.2	17.5	15.0
Allowance for inventory liquidation and obsolescence
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	81.5	75.0	65.4
Charged to costs and expenses	21.6	31.9	28.9
Charged to other accounts	0.0	0.0	0.0
Deductions	22.5	25.4	19.3
Balance at end of period	80.6	81.5	75.0
Allowance for inventory shrinkage
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	1.3	0.7	1.0
Charged to costs and expenses	3.3	1.7	1.1
Charged to other accounts	0.0	0.0	0.0
Deductions	3.2	1.1	1.4
Balance at end of period	1.4	1.3	0.7
Deferred tax valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	8.5	9.6	24.1
Charged to costs and expenses	3.2	0.2	2.3
Charged to other accounts	0.0	0.0	0.0
Deductions	0.8	1.3	16.8
Balance at end of period	$ 10.9	$ 8.5	$ 9.6