Junior Subordinated Debt - Summary of Terms and Recorded Balance of Subordinated Debenture (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Oct. 03, 2014
Subordinated Borrowing [Line Items]
Subordinated debenture, Face Value	$ 62,889,000
Subordinated debenture, Recorded Book Value	$ 56,858,000	$ 56,667,000
TriCo Capital Trust I [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Maturity Date	Oct. 07, 2033
Subordinated debenture, Face Value	$ 20,619,000
Subordinated debenture, Current Coupon Rate	4.41%
Subordinated debenture, Recorded Book Value	$ 20,619,000
TriCo Capital Trust II [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Maturity Date	Jul. 23, 2034
Subordinated debenture, Face Value	$ 20,619,000
Subordinated debenture, Current Coupon Rate	3.91%
Subordinated debenture, Recorded Book Value	$ 20,619,000
North Valley Trust II [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Maturity Date	Apr. 24, 2033
Subordinated debenture, Face Value	$ 6,186,000
Subordinated debenture, Current Coupon Rate	4.63%
Subordinated debenture, Recorded Book Value	$ 5,135,000		$ 5,006,000
North Valley Trust III [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Maturity Date	Apr. 24, 2034
Subordinated debenture, Face Value	$ 5,155,000
Subordinated debenture, Current Coupon Rate	4.16%
Subordinated debenture, Recorded Book Value	$ 4,041,000		3,918,000
North Valley Trust IV [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Maturity Date	Mar. 15, 2036
Subordinated debenture, Face Value	$ 10,310,000
Subordinated debenture, Current Coupon Rate	2.92%
Subordinated debenture, Recorded Book Value	$ 6,444,000		$ 6,063,000
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%