| Cover Page Document | Jun. 09, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Jun. 9, 2021 |
| Entity Registrant Name | Corcept Therapeutics Incorporated |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 000-50679 |
| Entity Tax Identification Number | 77-0487658 |
| Entity Address, Address Line One | 149 Commonwealth Drive |
| Entity Address, City or Town | Menlo Park |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 94025 |
| City Area Code | 650 |
| Local Phone Number | 327-3270 |
| Entity Information, Former Legal or Registered Name | Not Applicable |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.001 par value |
| Trading Symbol | CORT |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001088856 |
| Amendment Flag | false |
