| Cover | Aug. 24, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Aug. 24, 2021 |
| Entity File Number | 000-23186 |
| Entity Registrant Name | BioCryst Pharmaceuticals, Inc. |
| Entity Central Index Key | 0000882796 |
| Entity Tax Identification Number | 62-1413174 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 4505 Emperor Blvd., Suite 200 |
| Entity Address, City or Town | Durham |
| Entity Address, State or Province | NC |
| Entity Address, Postal Zip Code | 27703 |
| City Area Code | 919 |
| Local Phone Number | 859-1302 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock |
| Trading Symbol | BCRX |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
