| Document and Entity Information | Aug. 04, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K/A |
| Amendment Flag | true |
| Amendment Description | This Form 8-K/A amends the current report on Form 8-K of TechTarget, Inc. filed with the Securities and Exchange Commission on August 4, 2021 (the “Original Filing”). This amendment is required to correct the tabular information for adjusted revenue, expected impact of fair value adjustment of unearned revenue, and revenue presented in the Financial Guidance for the Three Months Ended September 30, 2021 table provided in the Shareholder Letter dated August 4, 2021 as Exhibit 99.1 This Form 8-K/A is being filed solely for the purpose of re-furnishing as Exhibit 99.1 the corrected version of our Shareholder Letter dated August 4, 2021. |
| Document Period End Date | Aug. 4, 2021 |
| Entity Registrant Name | TechTarget, Inc. |
| Entity Central Index Key | 0001293282 |
| Entity Emerging Growth Company | false |
| Entity File Number | 1-33472 |
| Entity Incorporation State 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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $0.001 per value per share |
| Trading Symbol | TTGT |
| Security Exchange Name | NASDAQ |
