Junior Subordinated Debt - Summary of Terms and Recorded Balance of Subordinated Debenture (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Subordinated Borrowing [Line Items]
Subordinated debenture, Face Value	$ 62,889
Subordinated debenture, Recorded Book Value	$ 57,042	$ 56,858
TriCo Capital Trust I [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Maturity Date	Oct. 07, 2033
Subordinated debenture, Face Value	$ 20,619
Subordinated debenture, Current Coupon Rate	5.49%
Subordinated debenture, Recorded Book Value	$ 20,619	20,619
TriCo Capital Trust II [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Maturity Date	Jul. 23, 2034
Subordinated debenture, Face Value	$ 20,619
Subordinated debenture, Current Coupon Rate	5.03%
Subordinated debenture, Recorded Book Value	$ 20,619	20,619
North Valley Trust II [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Maturity Date	Apr. 24, 2033
Subordinated debenture, Face Value	$ 6,186
Subordinated debenture, Current Coupon Rate	5.79%
Subordinated debenture, Recorded Book Value	$ 5,174	5,135
North Valley Trust III [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Maturity Date	Apr. 24, 2034
Subordinated debenture, Face Value	$ 5,155
Subordinated debenture, Current Coupon Rate	5.28%
Subordinated debenture, Recorded Book Value	$ 4,079	4,041
North Valley Trust IV [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Maturity Date	Mar. 15, 2036
Subordinated debenture, Face Value	$ 10,310
Subordinated debenture, Current Coupon Rate	4.12%
Subordinated debenture, Recorded Book Value	$ 6,551	$ 6,444
LIBOR PLUS [Member] | TriCo Capital Trust I [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Coupon Rate	3.05%
LIBOR PLUS [Member] | TriCo Capital Trust II [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Coupon Rate	2.55%
LIBOR PLUS [Member] | North Valley Trust II [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Coupon Rate	3.25%
LIBOR PLUS [Member] | North Valley Trust III [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Coupon Rate	2.80%
LIBOR PLUS [Member] | North Valley Trust IV [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Coupon Rate	1.33%