Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements - Additional Information (Detail)

v3.8.0.1
Fair Value Measurements - Additional Information (Detail) - USD ($)
12 Months Ended
Jan. 31, 2018
Jan. 31, 2017
Jan. 31, 2016
Fair Value Measurements Disclosure [Line Items]      
Fair value measurements of our financial assets and liabilities $ 13,008,000 $ 12,970,000  
Maximum maturity of marketable securities Three months or less    
Cash equivalents and marketable securities $ 52,100,000 38,700,000  
Restricted cash 9,000 109,000 $ 82,000
Cash Balances Related to Collateral for Performance Obligations [Member]      
Fair Value Measurements Disclosure [Line Items]      
Restricted cash   100,000  
Fair Value, Inputs, Level 3 [Member]      
Fair Value Measurements Disclosure [Line Items]      
Fair value measurements of our financial assets and liabilities $ 0 $ 0