TriCo Bancshares Condensed Financial Statements (Parent Only) - Condensed Balance Sheets, Nonprinting (Detail) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Condensed Financial Statements, Captions [Line Items]
Preferred stock, par value (in dollars per share)	$ 0	$ 0
Preferred stock, shares authorized (in shares)	1,000,000	1,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized (in shares)	50,000,000	50,000,000
Common stock, shares issued (in shares)	29,727,214	30,523,824
Common stock, shares outstanding (in shares)	29,727,214	30,523,824