v3.8.0.1
Document and Entity Information Document - USD ($)
12 Months Ended
Dec. 31, 2017
Feb. 20, 2018
Jul. 28, 2017
Document and Entity Information [Abstract]      
Entity Registrant Name Redfin Corp    
Entity Central Index Key 0001382821    
Current Fiscal Year End Date --12-31    
Entity Filer Category Non-accelerated Filer    
Document Type 10-K    
Document Period End Date Dec. 31, 2017    
Document Fiscal Year Focus 2017    
Document Fiscal Period Focus FY    
Amendment Flag false    
Entity Voluntary Filers No    
Entity Well Known Seasoned Issuer No    
Entity Current Reporting Status Yes    
Entity Common Stock, Shares Outstanding   81,778,130  
Entity Public Float     $ 1,326,046,855