Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Summary of Cash, Cash Equivalents and Available-for-Sale Securities (Detail)

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Fair Value Measurements - Summary of Cash, Cash Equivalents and Available-for-Sale Securities (Detail) (USD $)
In Thousands, unless otherwise specified
Oct. 31, 2014
Jan. 31, 2014
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost $ 108,368 $ 128,085
Gross Unrealized Gains 14 18
Gross Unrealized Losses (1)  
Estimated Fair Value 108,381 128,103
Cash [Member]
    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 92,526 112,271
Estimated Fair Value 92,526 112,271
Cash Equivalents [Member]
    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 2,046 3,463
Estimated Fair Value 2,046 3,463
Cash and Cash Equivalents [Member]
    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 94,572 115,734
Estimated Fair Value 94,572 115,734
U.S. Treasury Notes and Bonds - Short Term [Member]
    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 501 3,540
Gross Unrealized Gains   5
Estimated Fair Value 501 3,545
U.S. Treasury Notes and Bonds - Long Term [Member]
    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 3,520  
Gross Unrealized Losses (1)  
Estimated Fair Value 3,519  
U.S. Government Agency Issues Short Term [Member]
    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 5,517 2,005
Gross Unrealized Gains 7 5
Estimated Fair Value 5,524 2,010
U.S. Government Agency Issues Long Term [Member]
    
Schedule of Available-for-Sale Securities [Line Items]    
Amortized Cost 4,258 6,806
Gross Unrealized Gains 7 8
Estimated Fair Value $ 4,265 $ 6,814