| Cover | Nov. 10, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Nov. 10, 2021 |
| Entity File Number | 000-52776 |
| Entity Registrant Name | Appgate, Inc. |
| Entity Central Index Key | 0001353538 |
| Entity Tax Identification Number | 20-3547231 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 2333 Ponce De Leon Blvd |
| Entity Address, Address Line Two | Suite 900 |
| Entity Address, City or Town | Coral Gables |
| Entity Address, State or Province | FL |
| Entity Address, Postal Zip Code | 33134 |
| City Area Code | 866 |
| Local Phone Number | 524-4782 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
