Quarterly report pursuant to Section 13 or 15(d)

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

v3.8.0.1
Fair Value Measurements - Fair Value of Financial Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($)
$ in Thousands
Oct. 31, 2017
Jan. 31, 2017
Available-for-sale marketable securities:    
Marketable securities, short-term $ 4,990 $ 5,253
Non-current marketable securities:    
Marketable securities, long-term 4,485 4,991
Total 13,025 12,970
U.S. Treasury Notes and Bonds Conventional [Member]    
Available-for-sale marketable securities:    
Marketable securities, short-term 1,993 4,253
Non-current marketable securities:    
Marketable securities, long-term 1,735 1,997
U.S. Government Agency Issues Short Term [Member]    
Available-for-sale marketable securities:    
Marketable securities, short-term 2,997 1,000
U.S. Government Agency Issues Long Term [Member]    
Non-current marketable securities:    
Marketable securities, long-term 993 2,994
Corporate Bonds [Member]    
Non-current marketable securities:    
Marketable securities, long-term 1,757  
Cash Equivalents [Member]    
Financial assets:    
Cash equivalents 3,550 2,726
Fair Value, Inputs, Level 1 [Member]    
Non-current marketable securities:    
Total 4,228 8,976
Fair Value, Inputs, Level 1 [Member] | U.S. Treasury Notes and Bonds Conventional [Member]    
Available-for-sale marketable securities:    
Marketable securities, short-term 1,993 4,253
Non-current marketable securities:    
Marketable securities, long-term 1,735 1,997
Fair Value, Inputs, Level 1 [Member] | Cash Equivalents [Member]    
Financial assets:    
Cash equivalents 500 2,726
Fair Value, Inputs, Level 2 [Member]    
Non-current marketable securities:    
Total 8,797 3,994
Fair Value, Inputs, Level 2 [Member] | U.S. Government Agency Issues Short Term [Member]    
Available-for-sale marketable securities:    
Marketable securities, short-term 2,997 1,000
Fair Value, Inputs, Level 2 [Member] | U.S. Government Agency Issues Long Term [Member]    
Non-current marketable securities:    
Marketable securities, long-term 993 $ 2,994
Fair Value, Inputs, Level 2 [Member] | Corporate Bonds [Member]    
Non-current marketable securities:    
Marketable securities, long-term 1,757  
Fair Value, Inputs, Level 2 [Member] | Cash Equivalents [Member]    
Financial assets:    
Cash equivalents $ 3,050