| Document and Entity Information | Nov. 03, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Nov. 3, 2021 |
| Entity Registrant Name | TRACON Pharmaceuticals, Inc. |
| Entity Tax Identification Number | 34-2037594 |
| Entity Central Index Key | 0001394319 |
| Entity File Number | 001-36818 |
| Entity Emerging Growth Company | false |
| Title of 12(b) Security | Common Stock, par value $0.001 per share |
| Trading Symbol | TCON |
| Security Exchange Name | NASDAQ |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 4350 La Jolla Village Drive |
| Entity Address, Address Line Two | Suite 800 |
| Entity Address, City or Town | San Diego |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 92122 |
| City Area Code | 858 |
| Local Phone Number | 550-0780 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
