Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies (Details)

v2.4.0.6
Summary of Significant Accounting Policies (Details) (USD $)
 1 Months Ended 12 Months Ended
Sep. 30, 2011
Jan. 31, 2013
Jan. 31, 2012
Jan. 31, 2011
Revenue Recognition        
Deferred revenue related to refund rights   $ 5,100,000    
Number of hours per month listening cap on desktop and laptop computers eliminated 40 hours      
Maximum listening number of hours per month 320 hours      
Internal Use Software and Website Development Costs        
Capitalized cost related to internal use software and website development costs   1,100,000 100,000  
Preferred Stock Warrant        
Loss on revaluation of the convertible preferred stock warrant liability     4,500,000 900,000
Stock-Based Compensation        
Service period over which company recognizes stock-based compensation   4 years    
Marketing and Sales        
Advertising expenses   $ 7,600,000 $ 6,900,000 $ 3,000,000
Servers, computers, and other related equipment
        
Property and Equipment        
Estimated useful lives   3 years    
Office furniture and equipment | Minimum
        
Property and Equipment        
Estimated useful lives   3 years    
Office furniture and equipment | Maximum
        
Property and Equipment        
Estimated useful lives   5 years    
Leasehold improvements
        
Property and Equipment        
Estimated useful lives   5 years    
Internal use software and website development
        
Property and Equipment        
Estimated useful lives   3 years