Document and Entity Information - USD ($)
12 Months Ended
Dec. 31, 2017
Feb. 22, 2018
Jun. 30, 2017
Document and Entity Information      
Entity Registrant Name TrueCar, Inc.    
Entity Central Index Key 0001327318    
Current Fiscal Year End Date --12-31    
Entity Filer Category Large Accelerated Filer    
Document Type 10-K    
Entity Current Reporting Status Yes    
Document Period End Date Dec. 31, 2017    
Document Fiscal Year Focus 2017    
Document Fiscal Period Focus (Q1,Q2,Q3,FY) FY    
Amendment Flag false    
Entity Common Stock, Shares Outstanding   100,558,696  
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Public Float     $ 1,438,690,916