TriCo Bancshares Condensed Financial Statements (Parent Only) - Condensed Statements of Cash Flows (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Operating activities:
Net income	$ 20,458	$ 22,163
Adjustments to reconcile net income to net cash provided by operating activities:
Stock option excess tax benefits	(225)	(356)
Net cash provided by operating activities	21,751	33,632
Financing activities:
Stock option excess tax benefits	225	356
Repurchase of common stock	(292)	(501)
Cash dividends paid - common	(5,322)	(4,976)
Net cash used for financing activities	28,430	4,168
(Decrease) increase in cash and cash equivalents	(228,689)	(207,749)
Cash and cash equivalents and beginning of year	598,368	748,899
Cash and cash equivalents at end of period	369,679	541,150
Parent [Member]
Operating activities:
Net income	20,458	22,163
Adjustments to reconcile net income to net cash provided by operating activities:
Over (under) distributed equity in earnings of Tri Counties Bank	(15,823)	(16,955)
Stock option vesting expense	810	849
Stock option excess tax benefits	(225)	(356)
Net change in other assets and liabilities	(945)	(853)
Net cash provided by operating activities	4,275	4,848
Financing activities:
Issuance of common stock through option exercise	616	251
Stock option excess tax benefits	225	356
Repurchase of common stock	(292)	(501)
Cash dividends paid - common	(5,322)	(4,976)
Net cash used for financing activities	(4,773)	(4,870)
(Decrease) increase in cash and cash equivalents	(498)	(22)
Cash and cash equivalents and beginning of year	2,520	2,511
Cash and cash equivalents at end of period	$ 2,022	$ 2,489