| Document and Entity Information | Dec. 29, 2020 |
| Document and Entity Information [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Dec. 29, 2020 |
| Entity Registrant Name | NEOS THERAPEUTICS, INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-37508 |
| Entity Tax Identification Number | 27-0395455 |
| Entity Address, Address Line One | 2940 N. Highway 360 |
| Entity Address, City or Town | Grand Prairie |
| Entity Address, State or Province | TX |
| Entity Address, Postal Zip Code | 75050 |
| City Area Code | 972 |
| Local Phone Number | 408-1300 |
| Written Communications | true |
| 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 | NEOS |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | true |
| Entity Central Index Key | 0001467652 |
| Amendment Flag | false |
