TriCo Bancshares Condensed Financial Statements (Parent Only) - Condensed Balance Sheets (Parenthetical) (Detail) - $ / shares	Jun. 30, 2018	Dec. 31, 2017	Aug. 21, 2007
Condensed Financial Statements, Captions [Line Items]
Preferred stock, par value	$ 0	$ 0
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0	$ 0
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	23,004,153	22,955,963
Common stock, shares outstanding	23,004,153	22,955,963	15,814,662
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Preferred stock, par value	$ 0	$ 0
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0	$ 0
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	23,004,153	22,955,963
Common stock, shares outstanding	23,004,153	22,955,963