Number of countries contributes more than concentration threshold.

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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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.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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

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

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Revenues - Additional Information (Details) $ in Millions	3 Months Ended		9 Months Ended
Revenues - Additional Information (Details) $ in Millions	Oct. 31, 2019 USD ($)	Oct. 31, 2018 USD ($) Country	Oct. 31, 2019 USD ($) Country	Oct. 31, 2018 USD ($) Country	Jan. 31, 2019 USD ($)
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Deferred revenue	$ 325.6		$ 325.6		$ 375.0
Deferred revenue, revenue recognized out of beginning balance	141.5	$ 120.1	315.9	$ 252.1
Remaining performance obligation, revenue expected to be recognized	$ 636.0		$ 636.0
Revenue remaining performance obligation, percentage	68.00%		68.00%
Customer Concentration Risk \| Revenue
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Concentration risk percentage	10.00%	12.00%	10.00%	12.00%
Customer Concentration Risk \| United States \| Revenue
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Concentration risk percentage	75.00%	75.00%	75.00%	76.00%
Customer Concentration Risk \| Japan \| Revenue
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Concentration risk percentage	10.00%
Customer Concentration Risk \| Outside United States \| Revenue
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Number of countries outside domestic that contributes more than concentration threshold \| Country		0	0	0