| Document and Entity Information | Sep. 20, 2023 |
| Entity Addresses [Line Items] | |
| Document Type | 8-K |
| Document Period End Date | Sep. 20, 2023 |
| Entity Registrant Name | APPLIED MOLECULAR TRANSPORT INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-39306 |
| Entity Tax Identification Number | 81-4481426 |
| City Area Code | 650 |
| Local Phone Number | 392-0420 |
| 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 $0.0001 per share |
| Trading Symbol | AMTI |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001801777 |
| Amendment Flag | false |
| Business Contact [Member] | |
| Entity Addresses [Line Items] | |
| Entity Address, Address Line One | 1209 Orange Street |
| Entity Address, City or Town | Wilmington |
| Entity Address, Country | DE |
| Entity Address, Postal Zip Code | 19801 |
