Document and Entity Information - shares
9 Months Ended
Sep. 30, 2016
Oct. 31, 2016
Document And Entity Information [Abstract]    
Entity Registrant Name DEMAND MEDIA INC.  
Entity Central Index Key 0001365038  
Current Fiscal Year End Date --12-31  
Entity Filer Category Accelerated Filer  
Document Type 10-Q  
Document Period End Date Sep. 30, 2016  
Document Fiscal Year Focus 2016  
Document Fiscal Period Focus Q3  
Amendment Flag false  
Entity Common Stock, Shares Outstanding   19,761,455
Entity Current Reporting Status Yes