TriCo Bancshares Condensed Financial Statements (Parent Only) - Condensed Statements of Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Interest expense	$ 1,382us-gaap_InterestExpense	$ 1,437us-gaap_InterestExpense	$ 1,082us-gaap_InterestExpense	$ 1,075us-gaap_InterestExpense	$ 1,087us-gaap_InterestExpense
Income before income taxes	14,044	9,580	14,235	8,396	12,405
Equity in net income of Tri Counties Bank:
Income tax benefit	5,708us-gaap_IncomeTaxExpenseBenefit	3,930us-gaap_IncomeTaxExpenseBenefit	6,001us-gaap_IncomeTaxExpenseBenefit	3,537us-gaap_IncomeTaxExpenseBenefit	5,040us-gaap_IncomeTaxExpenseBenefit
Net income	8,336us-gaap_NetIncomeLoss	5,650us-gaap_NetIncomeLoss	8,234us-gaap_NetIncomeLoss	4,859us-gaap_NetIncomeLoss	7,365us-gaap_NetIncomeLoss
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Interest expense	482				304
Administration expense	153				324
Income before income taxes	(635)				(628)
Equity in net income of Tri Counties Bank:
Distributed	2,120				2,050
Under distributed	6,584				5,679
Income tax benefit	267				264
Net income	$ 8,336				$ 7,365

Over under distributed.

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The total amount of dividends declared in the period for each class of stock and the contractual amount of dividends (or interest on participating income bonds) that must be paid for the period (for example, unpaid cumulative dividends). Dividends declared in the current period do not include dividends declared in respect of prior-period unpaid cumulative dividends. Preferred dividends that are cumulative only if earned are deducted only to the extent that they are earned.

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Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the cost of borrowed funds accounted for as interest expense.

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