| Cover Page | Feb. 24, 2021 | Apr. 21, 2020 |
| Cover [Abstract] | ||
| Document Type | 8-K | |
| Document Period End Date | Feb. 24, 2021 | |
| Entity Registrant Name | Supernus Pharmaceuticals, Inc. | |
| Entity Incorporation, State or Country Code | DE | |
| Entity Filer Name | 001-35518 | |
| Entity Tax Identification Number | 20-2590184 | |
| Entity Address, Address Line One | 9715 Key West Ave | |
| Entity Address, City or Town | Rockville | |
| Entity Address, State or Province | MD | |
| Entity Address, Postal Zip Code | 20850 | |
| City Area Code | 301 | |
| Local Phone Number | 838-2500 | |
| Title of 12(b) Security | Common Stock, $0.001 par value per share | |
| Trading Symbol | SUPN | |
| Security Exchange Name | NASDAQ | |
| Written Communications | false | |
| Soliciting Material | false | |
| Pre-commencement Tender Offer | false | |
| Pre-commencement Issuer Tender Offer | false | |
| Entity Emerging Growth Company | false | |
| Amendment Flag | false | |
| Entity Central Index Key | 0001356576 |
