TriCo Bancshare Condensed Financial Statements (Parent Only) - Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended							9 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Sep. 30, 2016	Sep. 30, 2015
Condensed Financial Statements, Captions [Line Items]
Interest expense	$ (1,439)	$ (1,430)	$ (1,392)	$ (1,349)	$ (1,339)	$ (1,346)	$ (1,382)	$ (4,261)	$ (4,067)
Income before income taxes	19,893	14,911	17,232	18,810	21,062	18,798	14,044	52,036	53,904
Equity in net income of Tri Counties Bank:
Income tax benefit	(7,694)	(5,506)	(6,558)	(7,388)	(8,368)	(7,432)	(5,708)	(19,758)	(21,508)
Net income	12,199	$ 9,405	$ 10,674	$ 11,422	12,694	$ 11,366	$ 8,336	32,278	32,396
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Interest expense	562				499			1,643	1,472
Administration expense	158				203			548	619
Income before income taxes	(720)				(702)			(2,191)	(2,091)
Equity in net income of Tri Counties Bank:
Distributed	4,096				3,255			11,434	8,968
(Over) under distributed	8,522				9,846			22,116	24,640
Income tax benefit	301				295			919	879
Net income	$ 12,199				$ 12,694			$ 32,278	$ 32,396