Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Summary of Marketable Securities by Security Type (Detail)

v3.19.2
Fair Value Measurements - Summary of Marketable Securities by Security Type (Detail) - USD ($)
$ in Thousands
Jul. 31, 2019
Jan. 31, 2019
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost $ 9,520 $ 10,364
Gross Unrealized Gains 72 17
Gross Unrealized Losses (3) (22)
Fair Value 9,589 10,359
U.S. Treasury Notes and Bonds [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 6,513 7,055
Gross Unrealized Gains 72 17
Fair Value 6,585 7,072
U.S. Agency Bonds [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 1,000 1,001
Gross Unrealized Losses (2) (9)
Fair Value 998 992
Corporate Bonds [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 2,007 2,308
Gross Unrealized Losses (1) (13)
Fair Value $ 2,006 $ 2,295