v3.19.3
Document and Entity Information - shares
9 Months Ended
Sep. 30, 2019
Oct. 31, 2019
Document Information [Line Items]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Sep. 30, 2019  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q3  
Trading Symbol TTD  
Entity Registrant Name THE TRADE DESK, INC  
Entity Central Index Key 0001671933  
Current Fiscal Year End Date --12-31  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Shell Company false  
Entity File Number 001-37879  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 27-1887399  
Entity Address, Address Line One 42 N. Chestnut Street  
Entity Address, City or Town Ventura  
Entity Address, State or Province CA  
Entity Address, Postal Zip Code 93001  
City Area Code 805  
Local Phone Number 585-3434  
Title of 12(b) Security Class A Common Stock  
Security Exchange Name NASDAQ  
Document Quarterly Report true  
Document Transition Report false  
Class A common stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   39,834,865
Class B common stock    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   5,299,496