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Fair Value Measurements - Additional Information (Details) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Apr. 30, 2019
Jan. 31, 2019
Fair Value Disclosures [Line Items]    
Financial assets, level 2 to level 1 transfers, amount $ 0 $ 0
Financial assets, level 1 to level 2 transfers, amount 0 0
Investments other-than-temporarily impaired 0  
Voxter Communications Inc.    
Fair Value Disclosures [Line Items]    
Acquisition-related contingent consideration accrued $ 200 $ 200