XML 81 R34.htm IDEA: XBRL DOCUMENT v2.4.0.6
Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)
In Thousands, unless otherwise specified
 12 Months Ended
Jan. 31, 2013
Jan. 31, 2012
Jan. 31, 2011
Summary Of Significant Accounting Policies [Line Items]      
Fair value of Company's ARS $ 378,071 $ 216,767  
Interest rate intervals of auction process 7, 28, 35 or 90 days    
Advertising costs reported as prepaid expenses 2,716 3,586  
Advertising expense 81,944 71,684 58,336
Foreign currency translation losses 1,455 (2,285) (429)
Accumulated Other Comprehensive Income (Loss)
      
Summary Of Significant Accounting Policies [Line Items]      
Foreign currency translation losses 8,582 10,037  
Unrealized loss on marketable securities, net of tax 200 1,475  
Change in unrealized gains / (losses) on marketable securities, tax (672) (556) 397
Furniture and Fixtures
      
Summary Of Significant Accounting Policies [Line Items]      
Average useful life (in years) 5 years    
Leasehold Improvements
      
Summary Of Significant Accounting Policies [Line Items]      
Depreciable life (in years) Lesser of the lease term or useful life for leasehold improvements    
Equipment | Minimum
      
Summary Of Significant Accounting Policies [Line Items]      
Average useful life (in years) 3 years    
Equipment | Maximum
      
Summary Of Significant Accounting Policies [Line Items]      
Average useful life (in years) 10 years    
Building
      
Summary Of Significant Accounting Policies [Line Items]      
Average useful life (in years) 39 years    
Auction Rate Securities
      
Summary Of Significant Accounting Policies [Line Items]      
Fair value of Company's ARS 4,330 20,197  
Temporary impairment of auction rate securities $ 595 $ 2,778