| Cover | Nov. 09, 2020 |
| Cover [Abstract] | |
| Entity Registrant Name | American Public Education, Inc. |
| Document Type | 8-K |
| Amendment Flag | false |
| Entity Central Index Key | 0001201792 |
| Document Period End Date | Nov. 9, 2020 |
| Entity Emerging Growth Company | false |
| Entity File Number | 001-33810 |
| Entity Incorporation, State or Country Code | DE |
| Entity Tax Identification Number | 01-0724376 |
| Entity Address, Address Line One | 111 W. Congress Street |
| Entity Address, City or Town | Charles Town |
| Entity Address, State or Province | WV |
| Entity Address, Postal Zip Code | 25414 |
| City Area Code | 304 |
| Local Phone Number | 724-3700 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock |
| Trading Symbol | APEI |
| Security Exchange Name | NASDAQ |
