| Document and Entity Information | Mar. 01, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Mar. 1, 2021 |
| Entity Registrant Name | ALPHATEC HOLDINGS, INC. |
| Entity Central Index Key | 0001350653 |
| Entity Emerging Growth Company | false |
| Entity File Number | 000-52024 |
| Entity Incorporation State Country Code | DE |
| Entity Tax Identification Number | 20-2463898 |
| Entity Address Address Line1 | 1950 Camino Vida Roble |
| Entity Address City Or Town | Carlsbad |
| Entity Address State Or Province | CA |
| Entity Address Postal Zip Code | 92008 |
| City Area Code | 760 |
| Local Phone Number | 431-9286 |
| 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 $.0001 per share |
| Trading Symbol | ATEC |
| Security Exchange Name | NASDAQ |
