Quarterly report pursuant to Section 13 or 15(d)

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

v3.7.0.1
Fair Value Measurements - Summary of Available-for-Sale Securities (Detail) - USD ($)
$ in Thousands
Jul. 31, 2017
Jan. 31, 2017
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost $ 35,581 $ 38,540
Gross Unrealized Gains 19 14
Gross Unrealized Losses (18) (8)
Estimated Fair Value 35,582 38,546
Cash [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 22,594 25,576
Estimated Fair Value 22,594 25,576
Cash Equivalents [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 2,698 2,726
Gross Unrealized Gains 3  
Estimated Fair Value 2,701 2,726
Cash and Cash Equivalents [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 25,292 28,302
Gross Unrealized Gains 3  
Estimated Fair Value 25,295 28,302
U.S. Treasury Notes and Bonds - Short Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 1,548 4,248
Gross Unrealized Gains 1 5
Gross Unrealized Losses (2)  
Estimated Fair Value 1,547 4,253
U.S. Treasury Notes and Bonds - Long Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 2,992 2,003
Gross Unrealized Losses (6) (6)
Estimated Fair Value 2,986 1,997
U.S. Government Agency Issues Short Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 2,983 991
Gross Unrealized Gains 15 9
Gross Unrealized Losses (2)  
Estimated Fair Value 2,996 1,000
U.S. Government Agency Issues Long Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 1,003 2,996
Gross Unrealized Losses (7) (2)
Estimated Fair Value 996 $ 2,994
Corporate Bonds Long Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 1,763  
Gross Unrealized Losses (1)  
Estimated Fair Value $ 1,762