Annual report pursuant to Section 13 and 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
Jan. 31, 2017
Jan. 31, 2016
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost $ 38,540 $ 70,970
Gross Unrealized Gains 14 32
Gross Unrealized Losses (8) (1)
Estimated Fair Value 38,546 71,001
Cash [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 25,576 55,079
Estimated Fair Value 25,576 55,079
Cash Equivalents [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 2,726 3,654
Estimated Fair Value 2,726 3,654
Cash and Cash Equivalents [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 28,302 58,733
Estimated Fair Value 28,302 58,733
U.S. Treasury Notes and Bonds - Short Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 4,248 503
Gross Unrealized Gains 5  
Gross Unrealized Losses   (1)
Estimated Fair Value 4,253 502
U.S. Treasury Notes and Bonds - Long Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 2,003 7,756
Gross Unrealized Gains   6
Gross Unrealized Losses (6)  
Estimated Fair Value 1,997 7,762
U.S. Government Agency Issues Short Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 991 1,001
Gross Unrealized Gains 9 1
Estimated Fair Value 1,000 1,002
U.S. Government Agency Issues Long Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 2,996 2,977
Gross Unrealized Gains   25
Gross Unrealized Losses (2)  
Estimated Fair Value $ 2,994 $ 3,002