TriCo Bancshares Condensed Financial Statements (Parent Only) - Condensed Balance Sheets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets
Cash and Cash equivalents	$ 305,612	$ 303,461	$ 610,728	$ 598,368
Other assets	74,743	48,591
Total assets	4,517,968	4,220,722
Liabilities and shareholders' equity
Other liabilities	67,364	65,293
Junior subordinated debt	56,667	56,470
Total liabilities	4,040,621	3,768,606
Shareholders' equity:
Common stock, no par value: authorized 50,000,000 shares; issued and outstanding 22,867,802 and 22,775,173 shares, respectively	252,820	247,587
Retained earnings	232,440	206,307
Accumulated other comprehensive loss, net	(7,913)	(1,778)
Total shareholders' equity	477,347	452,116	418,172	250,946
Total liabilities and shareholders' equity	4,517,968	4,220,722
Parent [Member]
Assets
Cash and Cash equivalents	2,802	2,565	$ 2,229	$ 2,520
Investment in Tri Counties Bank	529,907	504,655
Other assets	1,711	1,714
Total assets	534,420	508,934
Liabilities and shareholders' equity
Other liabilities	406	348
Junior subordinated debt	56,667	56,470
Total liabilities	57,073	56,818
Shareholders' equity:
Common stock, no par value: authorized 50,000,000 shares; issued and outstanding 22,867,802 and 22,775,173 shares, respectively	252,820	247,587
Retained earnings	232,440	206,307
Accumulated other comprehensive loss, net	(7,913)	(1,778)
Total shareholders' equity	477,347	452,116
Total liabilities and shareholders' equity	$ 534,420	$ 508,934