Business and Summary of Significant Accounting Policies - Adoption of New Accounting Standard - Income Statement (Details) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended								12 Months Ended
		Feb. 01, 2018	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net revenue			$ 737.3	$ 660.9	$ 611.7	$ 559.9	$ 553.8	$ 515.3	$ 501.8	$ 485.7	$ 2,569.8	$ 2,056.6	$ 2,031.0
Marketing and sales											1,183.9	1,087.3	1,022.5
Provision for income taxes			(31.7)	(35.2)	(16.0)	(18.6)	24.8	(8.6)	(17.6)	(8.2)	(38.1)	(9.6)	(58.3)
Net loss			$ 64.7	$ (23.7)	$ (39.4)	$ (82.4)	$ (173.5)	$ (119.8)	$ (144.0)	$ (129.6)	$ (80.8)	$ (566.9)	$ (582.1)
Basic net loss per share (in dollars per share)			$ 0.30	$ (0.11)	$ (0.18)	$ (0.38)	$ (0.79)	$ (0.55)	$ (0.66)	$ (0.59)	$ (0.37)	$ (2.58)	$ (2.61)
Diluted net loss per share (in dollars per share)			$ 0.29	$ (0.11)	$ (0.18)	$ (0.38)	$ (0.79)	$ (0.55)	$ (0.66)	$ (0.59)	$ (0.37)	$ (2.58)	$ (2.61)
As Adjusted
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Marketing and sales											$ 1,166.0
Provision for income taxes											(42.9)
Net loss											$ (90.9)
Basic net loss per share (in dollars per share)											$ (0.42)
Diluted net loss per share (in dollars per share)											$ (0.42)
Accounting Standards Update 2014-09 | Impact from the adoption of ASC 606 and 340-40
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net revenue		$ 89.0
Marketing and sales											$ (17.9)
Provision for income taxes											(4.8)
Net loss											$ (10.1)
Basic net loss per share (in dollars per share)											$ (0.05)
Diluted net loss per share (in dollars per share)											$ (0.05)
Maintenance and subscription
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net revenue											$ 2,437.4	$ 1,883.9	$ 1,546.2
Cost of revenue											216.0	214.4	191.7
Maintenance and subscription | As Adjusted
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of revenue											215.9
Maintenance and subscription | Accounting Standards Update 2014-09 | Impact from the adoption of ASC 606 and 340-40
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of revenue											(0.1)
Subscription
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net revenue											1,802.3	894.3	443.1
Subscription | As Adjusted
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net revenue											1,785.7
Subscription | Accounting Standards Update 2014-09 | Impact from the adoption of ASC 606 and 340-40
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net revenue											(16.6)
Maintenance
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net revenue											635.1	989.6	1,103.1
Maintenance | As Adjusted
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net revenue											640.8
Maintenance | Accounting Standards Update 2014-09 | Impact from the adoption of ASC 606 and 340-40
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net revenue											5.7
Other
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net revenue	[1]										132.4	172.7	484.8
Cost of revenue	[2]										54.4	$ 72.6	$ 110.2
Other | As Adjusted
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net revenue											121.1
Cost of revenue											55.5
Other | Accounting Standards Update 2014-09 | Impact from the adoption of ASC 606 and 340-40
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net revenue											(11.3)
Cost of revenue											$ 1.1

[1] Previously labeled as "License and other" in prior periods.

[2] Previously labeled as "Cost of license and other revenue" in prior periods.