| Cover | Dec. 20, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Dec. 20, 2021 |
| Entity File Number | 001-36279 |
| Entity Registrant Name | CARA THERAPEUTICS, INC. |
| Entity Central Index Key | 0001346830 |
| Entity Tax Identification Number | 75-3175693 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 4 Stamford Plaza |
| Entity Address, Address Line Two | 107 Elm Street |
| Entity Address, Address Line Three | 9th Floor |
| Entity Address, City or Town | Stamford |
| Entity Address, State or Province | CT |
| Entity Address, Postal Zip Code | 06902 |
| City Area Code | 203 |
| Local Phone Number | 406-3700 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common stock, par value $0.001 per share |
| Trading Symbol | CARA |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
