TriCo Bancshares Condensed Financial Statements (Parent Only) - Condensed Statements of Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Net income	$ 22,890	$ 23,395	$ 23,061	$ 22,726	$ 23,211	$ 16,170	$ 15,029	$ 13,910	$ 92,072	$ 68,320	$ 40,554
Other comprehensive income (loss), net of tax:
Increase (decrease) in unrealized gains on available for sale securities arising during the period									17,159	(12,434)	3,165
Change in minimum pension liability									(4,502)	388	(370)
Change in joint beneficiary agreement liablity									0	426	(110)
Other comprehensive income (loss)									12,657	(11,620)	2,685
Comprehensive income									104,729	56,700	43,239
Parent
Condensed Financial Statements, Captions [Line Items]
Net income									92,072	68,320	40,554
Other comprehensive income (loss), net of tax:
Increase (decrease) in unrealized gains on available for sale securities arising during the period									17,159	(12,434)	3,165
Change in minimum pension liability									(4,502)	388	(370)
Change in joint beneficiary agreement liablity									0	426	(110)
Other comprehensive income (loss)									12,657	(11,620)	2,685
Comprehensive income									$ 104,729	$ 56,700	$ 43,239