v2.4.0.8
Document and Entity Information (USD $)
12 Months Ended
Dec. 31, 2013
Jun. 30, 2013
Feb. 11, 2014
Class A Common Stock
Feb. 11, 2014
Class B Common Stock
Document Information [Line Items]        
Document Type 10-K      
Amendment Flag false      
Document Period End Date Dec. 31, 2013      
Document Fiscal Year Focus 2013      
Document Fiscal Period Focus FY      
Trading Symbol Z      
Entity Registrant Name ZILLOW INC      
Entity Central Index Key 0001334814      
Current Fiscal Year End Date --12-31      
Entity Well-known Seasoned Issuer Yes      
Entity Current Reporting Status Yes      
Entity Voluntary Filers No      
Entity Filer Category Large Accelerated Filer      
Entity Common Stock, Shares Outstanding     33,011,384 6,468,892
Entity Public Float   $ 1,270,616,234