TriCo Bancshares Condensed Financial Statements (Parent Only) - Condensed Statements of Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended							9 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Sep. 30, 2014	Sep. 30, 2013
Condensed Financial Statements, Captions [Line Items]
Interest expense	$ (1,082)	$ (1,075)	$ (1,087)	$ (1,123)	$ (1,169)	$ (1,167)	$ (1,237)	$ (3,244)	$ (3,573)
Income before income taxes	14,235	8,396	12,405	8,642	12,271	10,597	14,294	35,036	37,162
Equity in net income of Tri Counties Bank:
Income tax benefit	6,001	3,537	5,040	3,406	4,910	4,272	5,817	14,578	14,999
Net income	8,234	4,859	7,365	5,236	7,361	6,325	8,477	20,458	22,163
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Interest expense	310				314			920	936
Administration expense	722				191			1,512	568
Income before income taxes	(1,032)				(505)			(2,432)	(1,504)
Equity in net income of Tri Counties Bank:
Distributed	2,295				2,300			6,395	6,080
(Over) under distributed	6,744				5,354			15,823	16,955
Income tax benefit	227				212			672	632
Net income	$ 8,234				$ 7,361			$ 20,458	$ 22,163