TriCo Bancshares Parent Only Financial Statements (Unaudited) (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended						6 Months Ended
	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Jun. 30, 2012	Jun. 30, 2011
Operating activities:
Net income	$ 5,321	$ 3,931	$ 6,549	$ 6,470	$ 2,771	$ 2,800	$ 9,252	$ 5,571
Adjustments to reconcile net income to net cash provided by operating activities:
Stock option vesting expense							511	500
Stock option excess tax benefits							(21)	(296)
Net cash from operating activities							31,298	17,348
Financing activities:
Issuance of common stock through option exercise							156	436
Stock option excess tax benefits							21	296
Repurchase of common stock							(48)	(753)
Cash dividends paid - common							2,878	2,866
Net cash used for financing activities							(39,218)	(21,115)
Increase in cash and cash equivalents							6,827	19,988
Cash and cash equivalents at beginning of period		637,275		391,054		371,066	637,275	371,066
Cash and cash equivalents at end of period	644,102		637,275		391,054		644,102	391,054
Parent [Member]
Operating activities:
Net income	5,321				2,771		9,252	5,571
Adjustments to reconcile net income to net cash provided by operating activities:
Over (under) distributed equity in earnings of Tri Counties Bank							(4,505)	(20)
Stock option vesting expense							511	500
Net change in other assets and liabilities							(461)	(504)
Net cash from operating activities							4,776	3,190
Financing activities:
Cash dividends paid - common							(2,878)	2,886
Net cash used for financing activities							(2,749)	(2,887)
Increase in cash and cash equivalents							2,027	303
Cash and cash equivalents at beginning of period		706				633	706	633
Cash and cash equivalents at end of period	$ 2,733				$ 936		$ 2,733	$ 936