Cover
| Cover | Dec. 10, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Dec. 10, 2021 |
| Entity File Number | 001-13387 |
| Entity Registrant Name | AEROCENTURY CORP. |
| Entity Central Index Key | 0001036848 |
| Entity Tax Identification Number | 94-3263974 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 3000 El Camino Real |
| Entity Address, Address Line Two | Bldg. 4 |
| Entity Address, Address Line Three | Suite 200 |
| Entity Address, City or Town | Palo Alto |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 94306 |
| City Area Code | 650 |
| Local Phone Number | 340-1888 |
| 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 $0.001 per share |
| Trading Symbol | ACY |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |