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Cover
 3 Months Ended
Oct. 26, 2020
Jul. 29, 2020
Sep. 30, 2020
Mar. 31, 2020
Cover [Abstract]        
Document Type     8-K  
Document Period End Date Oct. 26, 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