Quarterly report pursuant to Section 13 or 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
Apr. 30, 2020
Jan. 31, 2020
Marketable securities:    
Marketable securities $ 3,430 $ 4,617
U.S. Treasury Notes and Bonds [Member]    
Marketable securities:    
Marketable securities 3,173 3,360
Corporate Bonds [Member]    
Marketable securities:    
Marketable securities 257 1,257
Fair Value, Measurements, Recurring [Member]    
Assets:    
Cash equivalents 134 1,408
Marketable securities:    
Total 3,564 6,025
Fair Value, Measurements, Recurring [Member] | U.S. Treasury Notes and Bonds [Member]    
Marketable securities:    
Marketable securities 3,173 3,360
Fair Value, Measurements, Recurring [Member] | Corporate Bonds [Member]    
Marketable securities:    
Marketable securities 257 1,257
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]    
Assets:    
Cash equivalents   1,408
Marketable securities:    
Total 3,173 4,768
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Treasury Notes and Bonds [Member]    
Marketable securities:    
Marketable securities 3,173 3,360
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]    
Assets:    
Cash equivalents 134  
Marketable securities:    
Total 391 1,257
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate Bonds [Member]    
Marketable securities:    
Marketable securities $ 257 $ 1,257