Quarterly report pursuant to Section 13 or 15(d)

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

v3.4.0.3
Fair Value Measurements - Summary of Available-for-Sale Securities (Detail) - USD ($)
$ in Thousands
Apr. 30, 2016
Jan. 31, 2016
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost $ 64,249 $ 70,970
Gross Unrealized Gains 40 32
Gross Unrealized Losses   (1)
Estimated Fair Value 64,289 71,001
Cash [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 48,343 55,079
Estimated Fair Value 48,343 55,079
Cash Equivalents [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 3,169 3,654
Estimated Fair Value 3,169 3,654
Cash and Cash Equivalents [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 51,512 58,733
Estimated Fair Value 51,512 58,733
U.S. Treasury Notes and Bonds - Short Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 3,754 503
Gross Unrealized Gains 3  
Gross Unrealized Losses   (1)
Estimated Fair Value 3,757 502
U.S. Treasury Notes and Bonds - Long Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 4,502 7,756
Gross Unrealized Gains 11 6
Estimated Fair Value 4,513 7,762
U.S. Government Agency Issues Short Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 1,001 1,001
Gross Unrealized Gains 1 1
Estimated Fair Value 1,002 1,002
U.S. Government Agency Issues Long Term [Member]    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 3,480 2,977
Gross Unrealized Gains 25 25
Estimated Fair Value $ 3,505 $ 3,002