FINANCIAL STATEMENT SCHEDULE II (Details) - USD ($) $ in Millions		12 Months Ended
		Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Allowance for doubtful accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at the Beginning of Year		$ 7.6	$ 6.3	$ 4.9
Valuation Allowances and Reserves, Charged to Cost and Expense		(3.3)	2.3	1.6
Deductions and Write-Offs		2.8	1.0	0.2
Balance at End of Year		1.5	7.6	6.3
Product returns reserves
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at the Beginning of Year		1.6	2.6	4.0
Valuation Allowances and Reserves, Charged to Cost and Expense		(7.7)	10.4	17.4
Deductions and Write-Offs		(6.3)	11.4	18.8
Balance at End of Year		0.2	1.6	2.6
Partner Program reserves
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at the Beginning of Year	[1]	45.2	36.5	38.4
Valuation Allowances and Reserves, Charged to Cost and Expense	[1]	240.3	267.4	237.3
Deductions and Write-Offs	[1]	257.4	258.7	239.2
Balance at End of Year	[1]	28.1	45.2	36.5
Restructuring
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at the Beginning of Year		1.3	1.6	5.6
Valuation Allowances and Reserves, Charged to Cost and Expense		77.8	0.0	3.2
Deductions and Write-Offs		70.7	0.3	7.2
Balance at End of Year		$ 8.4	$ 1.3	$ 1.6

[1] The partner program reserves balance impacts "Accounts receivable, net" and "Accounts payable" on the accompanying Consolidated Balance Sheets.