TriCo Bancshares Parent Only Financial Statements (Unaudited) (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended							9 Months Ended
	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Sep. 30, 2012	Sep. 30, 2011
Condensed Financial Statements, Captions [Line Items]
Net income	$ 5,020	$ 5,321	$ 3,931	$ 6,549	$ 6,470	$ 2,771	$ 2,800	$ 14,272	$ 12,041
Other comprehensive income, net of tax:
Unrealized holding gains (losses) on securities arising during the period	98				824			(176)	2,158
Other comprehensive loss	98				824			(176)	2,158
Comprehensive income	5,118				7,294			14,096	14,199
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	5,020				6,470			14,272	12,041
Other comprehensive income, net of tax:
Unrealized holding gains (losses) on securities arising during the period	98				824			(176)	2,158
Other comprehensive loss	98				824			(176)	2,158
Comprehensive income	$ 5,118				$ 7,294			$ 14,096	$ 14,199