Annual report pursuant to Section 13 and 15(d)

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

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Fair Value Measurements - Fair Value of Financial Assets Measured on Recurring Basis (Detail) - USD ($)
$ in Thousands
Jan. 31, 2019
Jan. 31, 2018
Marketable securities:    
Marketable securities $ 10,359 $ 8,440
U.S. Treasury Notes and Bonds [Member]    
Marketable securities:    
Marketable securities 7,072 3,717
U.S. Agency Bonds [Member]    
Marketable securities:    
Marketable securities 992 2,983
Corporate Bonds [Member]    
Marketable securities:    
Marketable securities 2,295 1,740
Fair Value, Measurements, Recurring [Member]    
Assets:    
Cash equivalents 2,887 4,568
Marketable securities:    
Total 13,246 13,008
Fair Value, Measurements, Recurring [Member] | U.S. Treasury Notes and Bonds [Member]    
Marketable securities:    
Marketable securities 7,072 3,717
Fair Value, Measurements, Recurring [Member] | U.S. Agency Bonds [Member]    
Marketable securities:    
Marketable securities 992 2,983
Fair Value, Measurements, Recurring [Member] | Corporate Bonds [Member]    
Marketable securities:    
Marketable securities 2,295 1,740
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]    
Assets:    
Cash equivalents 2,724  
Marketable securities:    
Total 9,796 3,717
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Treasury Notes and Bonds [Member]    
Marketable securities:    
Marketable securities 7,072 3,717
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]    
Assets:    
Cash equivalents 163 4,568
Marketable securities:    
Total 3,450 9,291
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Agency Bonds [Member]    
Marketable securities:    
Marketable securities 992 2,983
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate Bonds [Member]    
Marketable securities:    
Marketable securities $ 2,295 $ 1,740