TriCo Bancshares Condensed Financial Statements (Parent Only) - Condensed Statements of Cash Flows (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating activities
Net income	$ 92,072	$ 68,320	$ 40,554
Adjustments to reconcile net income to net cash provided by operating activities:
Equity compensation vesting expense	1,654	1,462	1,586
Net cash from operating activities	102,806	91,069	55,381
Financing activities
Issuance of common stock through option exercise	9	218	396
Repurchase of common stock, net	(2,196)	(2,483)	(1,629)
Cash dividends paid — common	(24,999)	(18,769)	(15,131)
Net cash from financing activities	(24,043)	73,039	201,880
Net change in cash and cash equivalents	48,974	22,105	(100,184)
Cash and cash equivalents at beginning of year	227,533	205,428	305,612
Cash and cash equivalents at end of year	276,507	227,533	205,428
Parent
Operating activities
Net income	92,072	68,320	40,554
Adjustments to reconcile net income to net cash provided by operating activities:
Undistributed equity in earnings of Tri Counties Bank	(62,326)	(45,315)	(23,359)
Equity compensation vesting expense	1,654	1,462	1,586
Net change in other assets and liabilities	(1,580)	(4,983)	(1,295)
Net cash from operating activities	29,820	19,484	17,486
Financing activities
Issuance of common stock through option exercise	9	218	396
Repurchase of common stock, net	(2,196)	(2,483)	(1,629)
Cash dividends paid — common	(24,999)	(18,769)	(15,131)
Net cash from financing activities	(27,186)	(21,034)	(16,364)
Net change in cash and cash equivalents	2,634	(1,550)	1,122
Cash and cash equivalents at beginning of year	2,374	3,924	2,802
Cash and cash equivalents at end of year	$ 5,008	$ 2,374	$ 3,924