Financial Instruments (Effects of Derivative Instruments on Condensed Consolidated Statements of Operations) (Details) - USD ($) $ in Millions	3 Months Ended
Apr. 30, 2019	Apr. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Total net revenue	$ 735.5	$ 559.9
Marketing and sales	313.3	276.4
Research and development	205.6	172.8
General and administrative	99.1	72.9
Foreign currency contracts \| Designated as hedging instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) reclassified from accumulated other comprehensive income into income	0.7
Foreign currency contracts \| Designated as hedging instrument \| Subscription Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) reclassified from accumulated other comprehensive income into income	2.2
Foreign currency contracts \| Designated as hedging instrument \| Maintenance Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) reclassified from accumulated other comprehensive income into income	1.3
Foreign currency contracts \| Designated as hedging instrument \| Cost of subscription and maintenance revenue
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) reclassified from accumulated other comprehensive income into income	(0.1)
Foreign currency contracts \| Designated as hedging instrument \| Marketing and sales
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) reclassified from accumulated other comprehensive income into income	(1.6)
Foreign currency contracts \| Designated as hedging instrument \| Research and development
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) reclassified from accumulated other comprehensive income into income	(0.3)
Foreign currency contracts \| Designated as hedging instrument \| General and administrative
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) reclassified from accumulated other comprehensive income into income	(0.8)
Foreign currency contracts \| Derivatives not designated as hedging instruments \| Interest and other expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Gain recognized on derivatives	4.1	4.6
Subscription
Derivative Instruments, Gain (Loss) [Line Items]
Total net revenue	595.8	350.4
Maintenance
Derivative Instruments, Gain (Loss) [Line Items]
Total net revenue	112.0	181.2
Subscription and Maintenance
Derivative Instruments, Gain (Loss) [Line Items]
Total net revenue	707.8	531.6
Cost of revenue	$ 59.7	$ 50.4

The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

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The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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