Business and Summary of Significant Accounting Policies - Adoption of New Accounting Standard - Balance Sheet (Details) - USD ($) $ in Millions	Jan. 31, 2019	Feb. 01, 2018	Jan. 31, 2018
Current assets:
Accounts receivable, net	$ 474.3		$ 438.2
Prepaid expenses and other current assets	192.1		116.5
Deferred income taxes, net	65.3		81.7
Other assets	337.8		170.9
Current liabilities:
Deferred revenue	1,763.3		1,551.6
Other accrued liabilities	142.3		198.0
Long-term deferred revenue	328.1		403.5
Long-term income taxes payable	21.5		41.6
Long-term deferred income taxes	79.8		66.6
Accumulated deficit	(2,147.4)		$ (2,084.9)
Impact from the adoption of ASC 606 and 340-40 | Accounting Standards Update 2014-09
Current assets:
Accounts receivable, net	73.4
Prepaid expenses and other current assets	(79.4)
Deferred income taxes, net	7.0
Other assets	(17.9)
Current liabilities:
Deferred revenue	140.6
Other accrued liabilities	1.7
Long-term deferred revenue	37.2
Long-term income taxes payable	(0.2)
Long-term deferred income taxes	(6.7)
Accumulated deficit	(189.5)	$ 179.4
As Adjusted
Current assets:
Accounts receivable, net	547.7
Prepaid expenses and other current assets	112.7
Deferred income taxes, net	72.3
Other assets	319.9
Current liabilities:
Deferred revenue	1,903.9
Other accrued liabilities	144.0
Long-term deferred revenue	365.3
Long-term income taxes payable	21.3
Long-term deferred income taxes	73.1
Accumulated deficit	$ (2,336.9)