| Cover | Oct. 22, 2020 |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Oct. 22, 2020 |
| Entity File Number | 0-31525 |
| Entity Registrant Name | American River Bankshares |
| Entity Central Index Key | 0001108236 |
| Entity Tax Identification Number | 68-0352144 |
| Entity Incorporation, State or Country Code | CA |
| Entity Address, Address Line One | 3100 Zinfandel Drive, Suite 450 |
| Entity Address, City or Town | Rancho Cordova |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 95670 |
| City Area Code | 916 |
| Local Phone Number | 851-0123 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, no par value |
| Trading Symbol | AMRB |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
