Cover Page - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Mar. 12, 2020	Jun. 30, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	001-35982
Entity Registrant Name	TELARIA, INC.
Entity Central Index Key	0001375796
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-5480343
Entity Address, Address Line One	222 Broadway
Entity Address, Address Line Two	16th Floor
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10038
City Area Code	646
Local Phone Number	723-5300
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	TLRA
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 325.9
Entity Common Stock, Shares Outstanding		48,047,492
Documents Incorporated by Reference	Portions of the information called for by Part III of this Annual Report on Form 10-K, to the extent not set forth herein, are incorporated herein by reference from the definitive proxy statement relating to our 2020 annual meeting of stockholders. The proxy statement will be filed with the U.S. Securities and Exchange Commission not later than 120 days after December 31, 2019.