| Document and Entity Information | Aug. 09, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Aug. 9, 2021 |
| Entity Registrant Name | TURNING POINT THERAPEUTICS, INC. |
| Entity Central Index Key | 0001595893 |
| Entity Emerging Growth Company | false |
| Entity File Number | 001-38871 |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 46-3826166 |
| Entity Address, Address Line One | 10628 Science Center Drive |
| Entity Address, Address Line Two | Suite 200 |
| Entity Address, City or Town | San Diego |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 92121 |
| City Area Code | (858) |
| Local Phone Number | 926-5251 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.0001 par value per share |
| Trading Symbol | TPTX |
| Security Exchange Name | NASDAQ |
