TriCo Bancshare Condensed Financial Statements (Parent Only) - Condensed Statements of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended						6 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2016	Jun. 30, 2015
Operating activities:
Net income	$ 9,405	$ 10,674	$ 11,422	$ 12,694	$ 11,366	$ 8,336	$ 20,079	$ 19,702
Adjustments to reconcile net income to net cash provided by operating activities:
Equity compensation vesting expense							697	698
Net cash from operating activities							23,618	25,567
Investing activities: None
Repurchase of common stock							(335)	(31)
Cash dividends paid - common							(6,841)	(5,473)
Net cash used by financing activities							(50,840)	(46,187)
Net change in cash and cash equivalents							(86,675)	(441,225)
Cash and cash equivalents and beginning of year		303,461		169,503		610,728	303,461	610,728
Cash and cash equivalents at end of period	216,786		303,461		169,503		216,786	169,503
Parent [Member]
Operating activities:
Net income	9,405				11,366		20,079	19,702
Adjustments to reconcile net income to net cash provided by operating activities:
Over (under) distributed equity in earnings of Tri Counties Bank							(13,594)	(14,794)
Equity compensation vesting expense							697	698
Equity compensation net tax expense (excess tax benefit)							182	(30)
Net change in other assets and liabilities							(587)	(463)
Net cash from operating activities							6,777	5,113
Investing activities: None
Issuance of common stock through option exercise							483	30
Equity compensation net (excess tax benefit) tax expense							(182)	569
Repurchase of common stock							(335)	(31)
Cash dividends paid - common							(6,841)	(5,473)
Net cash used by financing activities							(6,875)	(4,905)
Net change in cash and cash equivalents							(98)	208
Cash and cash equivalents and beginning of year		$ 2,565		$ 2,437		$ 2,229	2,565	2,229
Cash and cash equivalents at end of period	$ 2,467		$ 2,565		$ 2,437		$ 2,467	$ 2,437