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Fair Value Measurements - Additional Information (Details) - USD ($)
12 Months Ended
Jan. 31, 2019
Jan. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Other than temporary impairment charge on investment   $ 1,282,000
Cost method investments, carrying value   $ 0
Transfers into level 1 to level 2, assets $ 0  
Transfers into level 2 to level 1, assets 0  
Transfers into level 1 to level 2, liabilities 0  
Transfers into level 2 to level 1, liabilities 0  
Transfers into level 3, assets 0  
Transfers out of level 3, assets 0  
Transfers into level 3, liabilities 0  
Transfers out of level 3, liabilities $ 0  
Short-term investment    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Fair value, investment The fair value of the short-term investment, which is a guaranteed investment certificate, is based on its purchase price plus one half of a percent calculated annually