TriCo Bancshare Condensed Financial Statements (Parent Only) - Statements of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended							9 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Sep. 30, 2016	Sep. 30, 2015
Operating activities:
Net income	$ 12,199	$ 9,405	$ 10,674	$ 11,422	$ 12,694	$ 11,366	$ 8,336	$ 32,278	$ 32,396
Adjustments to reconcile net income to net cash provided by operating activities:
Equity compensation vesting expense								1,078	1,051
Net cash from operating activities								38,884	44,364
Financing activities:
Repurchase of common stock								(384)	(54)
Cash dividends paid - common								(10,265)	(8,728)
Net cash provided by financing activities								40,109	66,853
Net change in cash and cash equivalents								11,627	(401,430)
Cash and cash equivalents and beginning of year			303,461	209,298			610,728	303,461	610,728
Cash and cash equivalents at end of period	315,088			303,461	209,298			315,088	209,298
Parent [Member]
Operating activities:
Net income	12,199				12,694			32,278	32,396
Adjustments to reconcile net income to net cash provided by operating activities:
Over (under) distributed equity in earnings of Tri Counties Bank								(22,116)	(24,640)
Equity compensation vesting expense								1,078	1,051
Equity compensation net (excess tax benefit) tax expense								182	57
Net change in other assets and liabilities								(906)	(746)
Net cash from operating activities								10,516	8,118
Financing activities:
Issuance of common stock through option exercise								518	660
Equity compensation net (excess tax benefit) tax expense								(182)	(57)
Repurchase of common stock								(384)	(54)
Cash dividends paid - common								(10,265)	(8,728)
Net cash provided by financing activities								(10,313)	(8,179)
Net change in cash and cash equivalents								203	(61)
Cash and cash equivalents and beginning of year			$ 2,565	2,168			$ 2,229	2,565	2,229
Cash and cash equivalents at end of period	$ 2,768			$ 2,565	$ 2,168			$ 2,768	$ 2,168