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
Apr. 30, 2016
Jan. 31, 2016
Available for sale marketable securities:    
Marketable securities, short-term $ 4,759 $ 1,504
Non-current marketable securities:    
Marketable securities, long-term 8,018 10,764
Total 15,946 15,922
U.S. Treasury Notes and Bonds Conventional [Member]    
Available for sale marketable securities:    
Marketable securities, short-term 3,757 502
Non-current marketable securities:    
Marketable securities, long-term 4,513 7,762
U.S. Government Agency Issues Short Term [Member]    
Available for sale marketable securities:    
Marketable securities, short-term 1,002 1,002
U.S. Government Agency Issues Long Term [Member]    
Non-current marketable securities:    
Marketable securities, long-term 3,505 3,002
Money Market Accounts [Member]    
Financial assets:    
Cash and cash equivalents 3,169 3,654
Fair Value, Inputs, Level 1 [Member]    
Non-current marketable securities:    
Total 11,439 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 3,757 502
Non-current marketable securities:    
Marketable securities, long-term 4,513 7,762
Fair Value, Inputs, Level 1 [Member] | Money Market Accounts [Member]    
Financial assets:    
Cash and cash equivalents 3,169 3,654
Fair Value, Inputs, Level 2 [Member]    
Non-current marketable securities:    
Total 4,507 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 1,002
Fair Value, Inputs, Level 2 [Member] | U.S. Government Agency Issues Long Term [Member]    
Non-current marketable securities:    
Marketable securities, long-term $ 3,505 $ 3,002