TriCo Bancshares Condensed Financial Statements (Parent Only) - Condensed Balance Sheets (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Assets
Cash and Cash equivalents	$ 216,786	$ 303,461	$ 169,503	$ 610,728
Other assets	54,239	48,591
Total assets	4,352,492	4,220,722
Liabilities and shareholders' equity Other liabilities	57,587	65,293
Junior subordinated debt	56,567	56,470
Total liabilities	3,878,624	3,768,606
Shareholders' equity:
Common stock, no par value: authorized 50,000,000 shares; issued and outstanding 22,822,325 and 22,775,173 shares, respectively	249,860	247,587
Retained earnings	217,935	206,307
Accumulated other comprehensive income (loss), net	6,073	(1,778)
Total shareholders' equity	473,868	452,116	431,144	418,172
Total liabilities and shareholders' equity	4,352,492	4,220,722
Parent [Member]
Assets
Cash and Cash equivalents	2,467	2,565	$ 2,437	$ 2,229
Investment in Tri Counties Bank	526,616	504,655
Other assets	1,725	1,714
Total assets	530,808	508,934
Liabilities and shareholders' equity Other liabilities	373	348
Junior subordinated debt	56,567	56,470
Total liabilities	56,940	56,818
Shareholders' equity:
Common stock, no par value: authorized 50,000,000 shares; issued and outstanding 22,822,325 and 22,775,173 shares, respectively	249,860	247,587
Retained earnings	217,935	206,307
Accumulated other comprehensive income (loss), net	6,073	(1,778)
Total shareholders' equity	473,868	452,116
Total liabilities and shareholders' equity	$ 530,808	$ 508,934