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
Apr. 30, 2017
Jan. 31, 2017
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost $ 37,079 $ 38,540
Gross Unrealized Gains 16 14
Gross Unrealized Losses (18) (8)
Estimated Fair Value 37,077 38,546
Cash [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 24,103 25,576
Estimated Fair Value 24,103 25,576
Cash Equivalents [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 2,740 2,726
Estimated Fair Value 2,740 2,726
Cash and Cash Equivalents [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 26,843 28,302
Estimated Fair Value 26,843 28,302
U.S. Treasury Notes and Bonds - Short Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 4,748 4,248
Gross Unrealized Gains 1 5
Gross Unrealized Losses (1)  
Estimated Fair Value 4,748 4,253
U.S. Treasury Notes and Bonds - Long Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 1,502 2,003
Gross Unrealized Losses (7) (6)
Estimated Fair Value 1,495 1,997
U.S. Government Agency Issues Short Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 2,482 991
Gross Unrealized Gains 15 9
Estimated Fair Value 2,497 1,000
U.S. Government Agency Issues Long Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 1,504 2,996
Gross Unrealized Losses (10) (2)
Estimated Fair Value $ 1,494 $ 2,994