TriCo Bancshares Condensed Financial Statements (Parent Only) (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012
Condensed Statements of Income
Interest expense	$ 1,237	$ 1,372	$ 1,834	$ 2,010	$ 2,128
Loss before equity in net income of Tri Counties Bank	14,294	8,132	8,636	8,773	6,390
Equity in net income of Tri Counties Bank:
Income tax benefit / expense	5,817	3,410	3,616	3,452	2,459
Net income	8,477	4,722	5,020	5,321	3,931
Parent [Member]
Condensed Statements of Income
Interest expense	311				338
Administration expense	145				131
Loss before equity in net income of Tri Counties Bank	(456)				(469)
Equity in net income of Tri Counties Bank:
Distributed	1,700				1,625
Under distributed	7,041				2,583
Income tax benefit / expense	192				192
Net income	$ 8,477				$ 3,931