TriCo Bancshare Condensed Financial Statements (Parent Only) - Condensed Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Interest expense	$ 1,349	$ 1,339	$ 1,346	$ 1,382	$ 1,437	$ 1,082	$ 1,075	$ 1,087	$ 5,416	$ 4,681	$ 4,696
Income before income taxes	18,810	21,062	18,798	14,044	9,580	14,235	8,396	12,405	72,714	44,616	45,804
Equity in net income of Tri Counties Bank:
Income tax benefit	(7,388)	(8,368)	(7,432)	(5,708)	(3,930)	(6,001)	(3,537)	(5,040)	(28,896)	(18,508)	(18,405)
Net income	$ 11,422	$ 12,694	$ 11,366	$ 8,336	$ 5,650	$ 8,234	$ 4,859	$ 7,365	43,818	26,108	27,399
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Interest expense									(1,977)	(1,403)	(1,247)
Administration expense									(814)	(2,720)	(862)
Income before income taxes									(2,791)	(4,123)	(2,109)
Equity in net income of Tri Counties Bank:
Distributed									13,304	8,270	8,175
Undistributed									32,131	20,720	20,446
Income tax benefit									1,174	1,241	887
Net income									$ 43,818	$ 26,108	$ 27,399