Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Fair Value of Financial Assets and Liabilities Measured on Recurring Basis (Detail)

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Fair Value Measurements - Fair Value of Financial Assets and Liabilities Measured on Recurring Basis (Detail) (USD $)
In Thousands, unless otherwise specified
Oct. 31, 2013
Jan. 31, 2013
Financial assets:    
Cash and cash equivalents $ 109,648 $ 104,109
Available for sale marketable securities:    
U.S. government agency issues - Current 3,021 6,104
Non-current marketable securities:    
U.S. government agency issues - Non current 8,360 7,169
Total 125,488 119,994
Other liabilities:    
Acquisition-related consideration   5,656
Money Market Accounts [Member]
   
Financial assets:    
Cash and cash equivalents 4,459 2,612
U.S. Government Agency Issues Short Term [Member]
   
Available for sale marketable securities:    
U.S. government agency issues - Current 3,021 6,104
U.S. Government Agency Issues Long Term [Member]
   
Non-current marketable securities:    
U.S. government agency issues - Non current 8,360 7,169
Fair Value, Inputs, Level 1 [Member]
   
Financial assets:    
Cash and cash equivalents 109,648 104,109
Non-current marketable securities:    
Total 125,488 119,994
Other liabilities:    
Acquisition-related consideration     
Fair Value, Inputs, Level 1 [Member] | Money Market Accounts [Member]
   
Financial assets:    
Cash and cash equivalents 4,459 2,612
Fair Value, Inputs, Level 1 [Member] | U.S. Government Agency Issues Short Term [Member]
   
Available for sale marketable securities:    
U.S. government agency issues - Current 3,021 6,104
Fair Value, Inputs, Level 1 [Member] | U.S. Government Agency Issues Long Term [Member]
   
Non-current marketable securities:    
U.S. government agency issues - Non current 8,360 7,169
Fair Value, Inputs, Level 2 [Member]
   
Financial assets:    
Cash and cash equivalents      
Non-current marketable securities:    
Total      
Other liabilities:    
Acquisition-related consideration     
Fair Value, Inputs, Level 2 [Member] | Money Market Accounts [Member]
   
Financial assets:    
Cash and cash equivalents      
Fair Value, Inputs, Level 2 [Member] | U.S. Government Agency Issues Short Term [Member]
   
Available for sale marketable securities:    
U.S. government agency issues - Current      
Fair Value, Inputs, Level 2 [Member] | U.S. Government Agency Issues Long Term [Member]
   
Non-current marketable securities:    
U.S. government agency issues - Non current      
Fair Value, Inputs, Level 3 [Member]
   
Financial assets:    
Cash and cash equivalents      
Non-current marketable securities:    
Total      
Other liabilities:    
Acquisition-related consideration   5,656
Fair Value, Inputs, Level 3 [Member] | Money Market Accounts [Member]
   
Financial assets:    
Cash and cash equivalents      
Fair Value, Inputs, Level 3 [Member] | U.S. Government Agency Issues Short Term [Member]
   
Available for sale marketable securities:    
U.S. government agency issues - Current      
Fair Value, Inputs, Level 3 [Member] | U.S. Government Agency Issues Long Term [Member]
   
Non-current marketable securities:    
U.S. government agency issues - Non current