Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Summary of Available-for-Sale Securities (Detail)

v3.10.0.1
Fair Value Measurements - Summary of Available-for-Sale Securities (Detail) - USD ($)
$ in Thousands
Jul. 31, 2018
Jan. 31, 2018
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost $ 34,483 $ 52,146
Gross Unrealized Gains 11 9
Gross Unrealized Losses (83) (63)
Estimated Fair Value 34,411 52,092
Cash [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 21,337 39,084
Estimated Fair Value 21,337 39,084
Cash Equivalents [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 3,045 4,568
Gross Unrealized Gains 11  
Estimated Fair Value 3,056 4,568
Cash and Cash Equivalents [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 24,382 43,652
Gross Unrealized Gains 11  
Estimated Fair Value 24,393 43,652
U.S. Treasury Notes and Bonds - Short Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 1,999 2,001
Gross Unrealized Losses (7) (8)
Estimated Fair Value 1,992 1,993
U.S. Treasury Notes and Bonds - Long Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 4,788 1,740
Gross Unrealized Losses (30) (16)
Estimated Fair Value 4,758 1,724
U.S. Government Agency Issues Short Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost   1,991
Gross Unrealized Gains   9
Gross Unrealized Losses   (2)
Estimated Fair Value   1,998
U.S. Government Agency Issues Long Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 1,001 1,002
Gross Unrealized Losses (16) (17)
Estimated Fair Value 985 985
Corporate Bonds Long Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 2,313 1,760
Gross Unrealized Losses (30) (20)
Estimated Fair Value $ 2,283 $ 1,740