Annual report pursuant to Section 13 and 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
Jan. 31, 2018
Jan. 31, 2017
Available-for-sale marketable securities:    
Marketable securities, short-term $ 3,991 $ 5,253
Non-current marketable securities:    
Marketable securities, long-term 4,449 4,991
Total 13,008 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 1,724 1,997
U.S. Government Agency Issues Short Term [Member]    
Available-for-sale marketable securities:    
Marketable securities, short-term 1,998 1,000
U.S. Government Agency Issues Long Term [Member]    
Non-current marketable securities:    
Marketable securities, long-term 985 2,994
Corporate Bonds [Member]    
Non-current marketable securities:    
Marketable securities, long-term 1,740  
Cash Equivalents [Member]    
Financial assets:    
Cash equivalents 4,568 2,726
Fair Value, Inputs, Level 1 [Member]    
Non-current marketable securities:    
Total 3,717 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 1,724 1,997
Fair Value, Inputs, Level 1 [Member] | Cash Equivalents [Member]    
Financial assets:    
Cash equivalents   2,726
Fair Value, Inputs, Level 2 [Member]    
Non-current marketable securities:    
Total 9,291 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 1,998 1,000
Fair Value, Inputs, Level 2 [Member] | U.S. Government Agency Issues Long Term [Member]    
Non-current marketable securities:    
Marketable securities, long-term 985 $ 2,994
Fair Value, Inputs, Level 2 [Member] | Corporate Bonds [Member]    
Non-current marketable securities:    
Marketable securities, long-term 1,740  
Fair Value, Inputs, Level 2 [Member] | Cash Equivalents [Member]    
Financial assets:    
Cash equivalents $ 4,568