| Cover Page Document | Nov. 18, 2020 | Aug. 04, 2020 |
| Cover [Abstract] | ||
| Document Type | 8-K | |
| Document Period End Date | Nov. 18, 2020 | |
| 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 | |
| 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 |
