Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Fair Value of Financial Assets and Liabilities Measured on Recurring Basis (Detail)

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Fair Value Measurements - Fair Value of Financial Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($)
$ in Thousands
Oct. 31, 2018
Jan. 31, 2018
Available-for-sale marketable securities:    
Marketable securities, short-term $ 1,732 $ 3,991
Non-current marketable securities:    
Marketable securities, long-term 8,554 4,449
Total 13,117 13,008
Money Market Accounts [Member]    
Financial assets:    
Cash and cash equivalents 2,832 4,568
U.S. Treasury Notes and Bonds Conventional [Member]    
Available-for-sale marketable securities:    
Marketable securities, short-term 745 1,993
Non-current marketable securities:    
Marketable securities, long-term 6,274 1,724
U.S. Government Agency Issues Short Term [Member]    
Available-for-sale marketable securities:    
Marketable securities, short-term   1,998
U.S. Government Agency Issues Long Term [Member]    
Non-current marketable securities:    
Marketable securities, long-term 986 985
Corporate Bonds [Member]    
Non-current marketable securities:    
Marketable securities, long-term 2,280 1,740
Fair Value, Inputs, Level 1 [Member]    
Non-current marketable securities:    
Total 9,668 3,717
Fair Value, Inputs, Level 1 [Member] | Money Market Accounts [Member]    
Financial assets:    
Cash and cash equivalents 2,649  
Fair Value, Inputs, Level 1 [Member] | U.S. Treasury Notes and Bonds Conventional [Member]    
Available-for-sale marketable securities:    
Marketable securities, short-term 745 1,993
Non-current marketable securities:    
Marketable securities, long-term 6,274 1,724
Fair Value, Inputs, Level 2 [Member]    
Non-current marketable securities:    
Total 3,449 9,291
Fair Value, Inputs, Level 2 [Member] | Money Market Accounts [Member]    
Financial assets:    
Cash and cash equivalents 183 4,568
Fair Value, Inputs, Level 2 [Member] | U.S. Government Agency Issues Short Term [Member]    
Available-for-sale marketable securities:    
Marketable securities, short-term   1,998
Fair Value, Inputs, Level 2 [Member] | U.S. Government Agency Issues Long Term [Member]    
Non-current marketable securities:    
Marketable securities, long-term 986 985
Fair Value, Inputs, Level 2 [Member] | Corporate Bonds [Member]    
Non-current marketable securities:    
Marketable securities, long-term $ 2,280 $ 1,740