Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Oct. 31, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Entity Registrant Name	TECHTARGET, INC.
Entity Central Index Key	0001293282
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding		28,098,707
Entity Shell Company	false
Title of 12(b) Security	Common Stock, $0.001 Par Value
Trading Symbol	TTGT
Security Exchange Name	NASDAQ
Entity File Number	1-33472
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	04-3483216
Entity Address, Address Line One	275 Grove Street
Entity Address, City or Town	Newton
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02466
City Area Code	617
Local Phone Number	431-9200
Document Quarterly Report	true
Document Transition Report	false