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, 2016
Jan. 31, 2016
Available-for-sale marketable securities:    
Marketable securities, short-term $ 4,256 $ 1,504
Non-current marketable securities:    
Marketable securities, long-term 6,014 10,764
Total 12,991 15,922
U.S. Treasury Notes and Bonds Conventional [Member]    
Available-for-sale marketable securities:    
Marketable securities, short-term 4,256 502
Non-current marketable securities:    
Marketable securities, long-term 2,004 7,762
U.S. Government Agency Issues Short Term [Member]    
Available-for-sale marketable securities:    
Marketable securities, short-term   1,002
U.S. Government Agency Issues Long Term [Member]    
Non-current marketable securities:    
Marketable securities, long-term 4,010 3,002
Money Market Accounts [Member]    
Financial assets:    
Cash and cash equivalents 2,721 3,654
Fair Value, Inputs, Level 1 [Member]    
Non-current marketable securities:    
Total 8,981 11,918
Fair Value, Inputs, Level 1 [Member] | U.S. Treasury Notes and Bonds Conventional [Member]    
Available-for-sale marketable securities:    
Marketable securities, short-term 4,256 502
Non-current marketable securities:    
Marketable securities, long-term 2,004 7,762
Fair Value, Inputs, Level 1 [Member] | Money Market Accounts [Member]    
Financial assets:    
Cash and cash equivalents 2,721 3,654
Fair Value, Inputs, Level 2 [Member]    
Non-current marketable securities:    
Total 4,010 4,004
Fair Value, Inputs, Level 2 [Member] | U.S. Government Agency Issues Short Term [Member]    
Available-for-sale marketable securities:    
Marketable securities, short-term   1,002
Fair Value, Inputs, Level 2 [Member] | U.S. Government Agency Issues Long Term [Member]    
Non-current marketable securities:    
Marketable securities, long-term $ 4,010 $ 3,002