Supplemental financial statement information (Other income (expense), net) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Interest income, net	$ 1,817	$ 234	$ 3,097	$ 425
Unrealized gain on marketable equity securities	3,774	0	27,285	0
Acquisition costs	(6,596)	(224)	(7,780)	(225)
Other	(123)	(85)	(130)	(276)
Total other income (expense), net	$ (1,128)	$ (75)	$ 22,472	$ (76)

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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Amount of unrealized gain (loss) on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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The net amount of operating interest income (expense).

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Amount of expense related to nonoperating activities, classified as other.

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