TriCo Bancshare Condensed Financial Statements (Parent Only) - Condensed Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended						6 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2016	Jun. 30, 2015
Condensed Financial Statements, Captions [Line Items]
Interest expense	$ (1,430)	$ (1,392)	$ (1,349)	$ (1,339)	$ (1,346)	$ (1,382)	$ (2,822)	$ (2,728)
Income before income taxes	14,911	17,232	18,810	21,062	18,798	14,044	32,143	32,842
Equity in net income of Tri Counties Bank:
Income tax benefit	(5,506)	(6,558)	(7,388)	(8,368)	(7,432)	(5,708)	(12,064)	(13,140)
Net income	9,405	$ 10,674	$ 11,422	$ 12,694	11,366	$ 8,336	20,079	19,702
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Interest expense	(546)				(491)		(1,081)	(973)
Administration expense	(241)				(263)		(390)	(416)
Income before income taxes	(787)				(754)		(1,471)	(1,389)
Equity in net income of Tri Counties Bank:
Distributed	3,658				3,593		7,338	5,713
(Over) under distributed	6,204				8,210		13,594	14,794
Income tax benefit	330				317		618	584
Net income	$ 9,405				$ 11,366		$ 20,079	$ 19,702