Quarterly report pursuant to Section 13 or 15(d)

Composition of Certain Financial Statement Captions (Details)

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Composition of Certain Financial Statement Captions (Details) (USD $)
In Thousands, unless otherwise specified
Jul. 31, 2012
Jan. 31, 2012
Jul. 31, 2011
Jan. 31, 2011
Cash, Cash Equivalents and Short-term Investments        
Total cash and cash equivalents $ 49,539 $ 44,126 $ 95,307 $ 43,048
Total short-term investments 32,758 46,455    
Cash, cash equivalents and short-term investments 82,297 90,581    
Cash
        
Cash, Cash Equivalents and Short-term Investments        
Total cash and cash equivalents 13,107 6,604    
Money market funds
        
Cash, Cash Equivalents and Short-term Investments        
Total cash and cash equivalents 31,932 31,614    
Commercial paper
        
Cash, Cash Equivalents and Short-term Investments        
Total cash and cash equivalents 3,000 2,893    
Total short-term investments 19,944 27,587    
Corporate debt securities
        
Cash, Cash Equivalents and Short-term Investments        
Total cash and cash equivalents 1,500 3,015    
Total short-term investments 10,314 17,968    
U.S. agency notes
        
Cash, Cash Equivalents and Short-term Investments        
Total short-term investments $ 2,500 $ 900