Revenues - Additional Information (Details) $ in Millions	3 Months Ended	6 Months Ended
Jul. 31, 2018 USD ($)	Jul. 31, 2018 USD ($)
Revenue From Contract With Customer [Abstract]
Contract assets presented within accounts receivable	$ 0.2	$ 0.2
Deferred revenue	301.5	301.5
Deferred revenue, revenue recognized out of beginning balance	115.2	197.6
Remaining performance obligation, revenue expected to be recognized	$ 587.2	$ 587.2
Revenue remaining performance obligation, percentage	66.00%	66.00%

Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
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Period Type:	instant

- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
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- Definition

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
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-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

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- References

No definition available.

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- Definition

Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130556-203045

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- Definition

Percentage of remaining performance obligation to total remaining performance obligation not recognized as revenue.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
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-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130556-203045

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