| Document and Entity Information | Nov. 18, 2021 |
| Document and Entity Information [Abstract] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001802665 |
| Document Type | 8-K |
| Document Period End Date | Nov. 18, 2021 |
| Entity File Number | 001-39450 |
| Entity Registrant Name | HARMONY BIOSCIENCES HOLDINGS, INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 82-2279923 |
| Entity Address, Address Line One | 630 W. Germantown Pike, Suite 215 |
| Entity Address, City or Town | Plymouth Meeting |
| Entity Address, State or Province | PA |
| Entity Address, Postal Zip Code | 19462 |
| City Area Code | 484 |
| Local Phone Number | 539-9800 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.00001 par value per share |
| Trading Symbol | HRMY |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
