| Cover | Jan. 28, 2020 |
| Cover page. | |
| Document Type | 8-K/A |
| Document Period End Date | Jan. 28, 2020 |
| Entity Registrant Name | TriCo Bancshares |
| Entity Incorporation, State or Country Code | CA |
| Entity File Number | 0-10661 |
| Entity Tax Identification Number | 94-2792841 |
| Entity Address, Address Line One | 63 Constitution Drive |
| Entity Address, City or Town | Chico, |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 95973 |
| City Area Code | 530 |
| Local Phone Number | 898-0300 |
| 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 | TCBK |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Entity Central Index Key | 0000356171 |
