Junior Subordinated Debt - Summary of Terms and Recorded Balance of Subordinated Debenture (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Subordinated Borrowing [Line Items]
Face Value	$ 62,889
Recorded Book Value	57,635	$ 57,232
TriCo Cap Trust I
Subordinated Borrowing [Line Items]
Face Value	$ 20,619
Current Coupon Rate	3.29%
Recorded Book Value	$ 20,619	20,619
TriCo Cap Trust II
Subordinated Borrowing [Line Items]
Face Value	$ 20,619
Current Coupon Rate	2.76%
Recorded Book Value	$ 20,619	20,619
North Valley Trust II
Subordinated Borrowing [Line Items]
Face Value	$ 6,186
Current Coupon Rate	3.46%
Recorded Book Value	$ 5,303	5,215
North Valley Trust III
Subordinated Borrowing [Line Items]
Face Value	$ 5,155
Current Coupon Rate	3.01%
Recorded Book Value	$ 4,199	4,118
North Valley Trust IV
Subordinated Borrowing [Line Items]
Face Value	$ 10,310
Current Coupon Rate	1.55%
Recorded Book Value	$ 6,894	$ 6,661
LIBOR PLUS | TriCo Cap Trust I
Subordinated Borrowing [Line Items]
Coupon Rate (Variable) 3 mo. LIBOR +	3.05%
LIBOR PLUS | TriCo Cap Trust II
Subordinated Borrowing [Line Items]
Coupon Rate (Variable) 3 mo. LIBOR +	2.55%
LIBOR PLUS | North Valley Trust II
Subordinated Borrowing [Line Items]
Coupon Rate (Variable) 3 mo. LIBOR +	3.25%
LIBOR PLUS | North Valley Trust III
Subordinated Borrowing [Line Items]
Coupon Rate (Variable) 3 mo. LIBOR +	2.80%
LIBOR PLUS | North Valley Trust IV
Subordinated Borrowing [Line Items]
Coupon Rate (Variable) 3 mo. LIBOR +	1.33%