v3.26.1
Junior Subordinated Debt (Detail) - USD ($)
$ in Thousands
3 Months Ended
Jun. 30, 2026
Dec. 31, 2025
Subordinated Borrowing [Line Items]    
Recorded Book Value $ 41,238 $ 41,238
Subordinated debt    
Subordinated Borrowing [Line Items]    
Face Value 41,238  
Recorded Book Value 41,238 41,238
TriCo Cap Trust I | Subordinated debt    
Subordinated Borrowing [Line Items]    
Face Value $ 20,619  
Coupon Rate (Variable) 3 mo. SOFR + 3.05%  
Current Coupon Rate 6.98%  
Recorded Book Value $ 20,619 20,619
TriCo Cap Trust II | Subordinated debt    
Subordinated Borrowing [Line Items]    
Face Value $ 20,619  
Coupon Rate (Variable) 3 mo. SOFR + 2.55%  
Current Coupon Rate 6.48%  
Recorded Book Value $ 20,619 $ 20,619