TriCo Bancshares (TCBK) 10-K 1 Mar 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Feb. 23, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Trading Symbol	TCBK
Entity Registrant Name	TRICO BANCSHARES /
Entity Central Index Key	356,171
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		22,956,323
Entity Public Float			$ 712,127,000

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets:
Cash and due from banks	$ 105,968	$ 92,197
Cash at Federal Reserve and other banks	99,460	213,415
Cash and cash equivalents	205,428	305,612
Investment securities:
Available for sale	730,883	550,233
Held to maturity	514,844	602,536
Restricted equity securities	16,956	16,956
Loans held for sale	4,616	2,998
Loans	3,015,165	2,759,593
Allowance for loan losses	(30,323)	(32,503)
Total loans, net	2,984,842	2,727,090
Foreclosed assets, net	3,226	3,986
Premises and equipment, net	57,742	48,406
Cash value of life insurance	97,783	95,912
Accrued interest receivable	13,772	12,027
Goodwill	64,311	64,311
Other intangible assets, net	5,174	6,563
Mortgage servicing rights	6,687	6,595
Other assets	55,051	74,743
Total assets	4,761,315	4,517,968
Deposits:
Noninterest-bearing demand	1,368,218	1,275,745
Interest-bearing	2,640,913	2,619,815
Total deposits	4,009,131	3,895,560
Accrued interest payable	930	818
Reserve for unfunded commitments	3,164	2,719
Other liabilities	63,258	67,364
Other borrowings	122,166	17,493
Junior subordinated debt	56,858	56,667
Total liabilities	4,255,507	4,040,621
Commitments and contingencies (Note 18)
Shareholders' equity:
Common stock, no par value: 50,000,000 shares authorized; issued and outstanding: 22,955,963 at December 31, 2017 22,867,802 at December 31, 2016	255,836	252,820
Retained earnings	255,200	232,440
Accumulated other comprehensive loss, net of tax	(5,228)	(7,913)
Total shareholders' equity	505,808	477,347
Total liabilities and shareholders' equity	$ 4,761,315	$ 4,517,968

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016	Aug. 21, 2007
Statement of Financial Position [Abstract]
Common stock, no par value	$ 0	$ 0
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	22,955,963	22,867,802
Common stock, shares outstanding	22,955,963	22,867,802	15,814,662

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest and dividend income:
Loans, including fees	$ 146,794	$ 141,086	$ 131,836
Debt securities:
Taxable	27,772	25,397	25,303
Tax exempt	4,165	3,881	1,509
Dividends	1,324	2,181	2,118
Interest bearing cash at Federal Reserve and other banks	1,347	1,163	648
Total interest and dividend income	181,402	173,708	161,414
Interest expense:
Deposits	3,958	3,483	3,434
Other borrowings	305	9	4
Junior subordinated debt	2,535	2,229	1,978
Total interest expense	6,798	5,721	5,416
Net interest income	174,604	167,987	155,998
Provision (benefit from reversal of provision previously provided) for loan losses	89	(5,970)	(2,210)
Net interest income after provision for loan losses	174,515	173,957	158,208
Noninterest income:
Service charges and fees	37,423	33,226	32,080
Gain on sale of loans	3,109	4,037	3,064
Commissions on sale of non-deposit investment products	2,729	2,329	3,349
Increase in cash value of life insurance	2,685	2,717	2,786
Other	4,075	2,254	4,068
Total noninterest income	50,021	44,563	45,347
Noninterest expense:
Salaries and related benefits	82,930	80,724	71,405
Other	64,094	65,273	59,436
Total noninterest expense	147,024	145,997	130,841
Income before income taxes	77,512	72,523	72,714
Provision for income taxes	36,958	27,712	28,896
Net income	$ 40,554	$ 44,811	$ 43,818
Earnings per share:
Basic	$ 1.77	$ 1.96	$ 1.93
Diluted	$ 1.74	$ 1.94	$ 1.91

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 2,989	$ 11,897	$ 13,589	$ 12,079	$ 12,533	$ 12,199	$ 9,405	$ 10,674	$ 40,554	$ 44,811	$ 43,818
Other comprehensive income (loss), net of tax:
Unrealized holding gain (losses) on securities arising during the period									3,165	(6,384)	(1,098)
Change in minimum pension liability									(370)	592	1,246
Change in joint beneficiary agreement liability									(110)	(343)	277
Other comprehensive income (loss)									2,685	(6,135)	425
Comprehensive income									$ 43,239	$ 38,676	$ 44,243

Consolidated Statements of Chan

Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balance at Dec. 31, 2014	$ 418,172	$ 244,318	$ 176,057	$ (2,203)
Beginning balance, shares at Dec. 31, 2014		22,714,964
Net income	43,818		43,818
Other comprehensive income (loss)	425			425
Stock option vesting	734	$ 734
RSU vesting	457	457
PSU vesting	179	179
Stock options exercised	3,116	$ 3,116
Stock options exercised, shares		154,500
Tax effect of stock options exercised	(83)	$ (83)
RSUs released	0	$ 0	0	0
RSUs released, shares		12,064
Tax benefit from release of RSUs	15	$ 15
Repurchase of common stock, value	(2,868)	$ (1,149)	(1,719)
Repurchase of common stock, shares		(106,355)
Dividends paid	(11,849)		(11,849)
Ending balance at Dec. 31, 2015	452,116	$ 247,587	206,307	(1,778)
Ending balance, shares at Dec. 31, 2015		22,775,173
Net income	44,811		44,811
Other comprehensive income (loss)	(6,135)			(6,135)
Stock option vesting	580	$ 580
RSU vesting	616	616
PSU vesting	271	271
Stock options exercised	6,506	$ 6,506
Stock options exercised, shares		336,900
Tax effect of stock options exercised	154	$ 154
RSUs released	0	$ 0	0	0
RSUs released, shares		20,529
Tax benefit from release of RSUs	1	$ 1
Repurchase of common stock, value	(7,878)	$ (2,895)	(4,983)
Repurchase of common stock, shares		(264,800)
Dividends paid	(13,695)		(13,695)
Ending balance at Dec. 31, 2016	$ 477,347	$ 252,820	232,440	(7,913)
Ending balance, shares at Dec. 31, 2016	22,867,802	22,867,802
Net income	$ 40,554		40,554
Other comprehensive income (loss)	2,685			2,685
Stock option vesting	259	$ 259
RSU vesting	895	895
PSU vesting	432	432
Stock options exercised	$ 2,621	$ 2,621
Stock options exercised, shares	145,850	145,850
RSUs released	$ 0	$ 0	0	0
RSUs released, shares		30,896
PSUs released	0	$ 0	0	0
PSUs released, shares		18,805
Repurchase of common stock, value	(3,854)	$ (1,191)	(2,663)
Repurchase of common stock, shares		(107,390)
Dividends paid	(15,131)		(15,131)
Ending balance at Dec. 31, 2017	$ 505,808	$ 255,836	$ 255,200	$ (5,228)
Ending balance, shares at Dec. 31, 2017	22,955,963	22,955,963

Consolidated Statements of Cha7

Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Dividends paid, per share	$ 0.66	$ 0.60	$ 0.52
Retained Earnings [Member]
Dividends paid, per share	$ 0.66	$ 0.60	$ 0.52

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities:
Net income	$ 40,554	$ 44,811	$ 43,818
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of premises and equipment, and amortization	6,787	6,474	5,906
Amortization of intangible assets	1,389	1,377	1,157
Provision for (benefit from reversal of) loan losses	89	(5,970)	(2,210)
Amortization of investment securities premium, net	3,200	4,926	3,458
Gain on sale of investment securities	(961)		0
Originations of loans for resale	(114,107)	(142,619)	(111,640)
Proceeds from sale of loans originated for resale	114,788	144,062	115,469
Gain on sale of loans	(3,109)	(4,037)	(3,064)
Change in market value of mortgage servicing rights	718	2,184	701
Provision for losses on foreclosed assets	162	140	502
Gain on sale of foreclosed assets	(711)	(262)	(991)
Provision for losses on fixed assets		782
Loss on disposal of fixed assets	142	147	129
Gain on sale of premises held for sale	(3)
Increase in cash value of life insurance	(2,685)	(2,717)	(2,786)
Gain on life insurance death benefit	(108)	(238)	(155)
Equity compensation vesting expense	1,586	1,467	1,370
Equity compensation tax effect		(155)	68
Deferred income tax expense	12,473	3,190	681
Change in:
Reserve for unfunded commitments	445	244	330
Interest receivable	(1,745)	(1,241)	(1,511)
Interest payable	112	44	(204)
Other assets and liabilities, net	(3,635)	(4,383)	3,789
Net cash from operating activities	55,381	48,226	54,817
Investing activities:
Proceeds from maturities of securities available for sale	63,942	71,684	33,552
Proceeds from sale of securities available for sale	25,757		2
Purchases of securities available for sale	(265,806)	(247,717)	(341,303)
Proceeds from maturities of securities held to maturity	86,371	121,666	93,784
Purchases of securities held to maturity			(146,100)
Loan origination and principal collections, net	(247,837)	(251,479)	(244,018)
Loans purchased	(11,567)	(22,503)
Proceeds from sale of loans other than loans originated for resale		37,880
Proceeds from sale of premises and equipment		1,682	8
Improvement of foreclosed assets			(195)
Proceeds from sale of other real estate owned	2,872	4,010	5,449
Proceeds from the sale of premises held for sale	3,338
Purchases of premises and equipment	(15,164)	(10,930)	(5,489)
Life insurance proceeds	649
Cash received from acquisition, net		156,316
Net cash used by investing activities	(357,445)	(139,391)	(604,310)
Financing activities:
Net increase in deposits	113,571	103,063	250,843
Net change in other borrowings	104,673	5,165	3,052
Equity compensation tax effect		155	(68)
Repurchase of common stock	(1,629)	(1,890)	(412)
Dividends paid	(15,131)	(13,695)	(11,849)
Exercise of stock options	396	518	660
Net cash from financing activities	201,880	93,316	242,226
Net change in cash and cash equivalents	(100,184)	2,151	(307,267)
Cash and cash equivalents and beginning of year	305,612	303,461	610,728
Cash and cash equivalents at end of year	205,428	305,612	303,461
Supplemental disclosure of noncash activities:
Unrealized loss on securities available for sale	5,461	(11,015)	(1,895)
Loans transferred to foreclosed assets	1,563	2,505	5,240
Due to broker			17,072
Market value of shares tendered in-lieu of cash to pay for exercise of options and/or related taxes	2,225	5,988	2,868
Supplemental disclosure of cash flow activity:
Cash paid for interest expense	5,609	5,677	5,620
Cash paid for income taxes	$ 21,170	27,575	$ 24,315
Assets acquired in acquisition		161,231
Liabilities assumed in acquisition		$ 161,231

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note 1 – Summary of Significant Accounting Policies Description of Business and Basis of Presentation TriCo Bancshares (the “Company” or “we”) is a California corporation organized to act as a bank holding company for Tri Counties Bank (the “Bank”). The Company and the Bank are headquartered in Chico, California. The Bank is a California-chartered bank that is engaged in the general commercial banking business in 26 California counties. The Bank operates from 57 traditional branches, 9 in-store The consolidated financial statements are prepared in accordance with accounting policies generally accepted in the United States of America and general practices in the banking industry. The financial statements include the accounts of the Company. All inter-company accounts and transactions have been eliminated in consolidation. For financial reporting purposes, the Company’s investments in the Capital Trusts of $1,721,000 are accounted for under the equity method and, accordingly, are not consolidated and are included in other assets on the consolidated balance sheet. The subordinated debentures issued and guaranteed by the Company and held by the Capital Trusts are reflected as debt on the Company’s consolidated balance sheet. Use of Estimates in the Preparation of Financial Statements The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires Management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions or conditions. Significant Group Concentration of Credit Risk The Company grants agribusiness, commercial, consumer, and residential loans to customers located throughout the northern San Joaquin Valley, the Sacramento Valley and northern mountain regions of California. The Company has a diversified loan portfolio within the business segments located in this geographical area. Management has determined that because all of the banking products and services offered by the Company are available in each branch of the Bank, all branches are located within the same economic environment and management does not allocate resources based on the performance of different lending or transaction activities, it is appropriate to aggregate the Bank branches and report them as a single operating segment. Cash and Cash Equivalents For purposes of the consolidated statements of cash flows, cash and cash equivalents include cash on hand, amounts due from banks, and federal funds sold. Net cash flows are reported for loan and deposit transactions and other borrowings. Investment Securities The Company classifies its debt and marketable equity securities into one of three categories: trading, available for sale or held to maturity. Trading securities are bought and held principally for the purpose of selling in the near term. Held to maturity securities are those securities which the Company has the ability and intent to hold until maturity. These securities are carried at cost adjusted for amortization of premium and accretion of discount, computed by the effective interest method over their contractual lives. All other securities not included in trading or held to maturity are classified as available for sale. Available for sale securities are recorded at fair value. Unrealized gains and losses, net of the related tax effect, on available for sale securities are reported as a separate component of other accumulated comprehensive income in shareholders’ equity until realized. Premiums and discounts are amortized or accreted over the life of the related investment security as an adjustment to yield using the effective interest method. Dividend and interest income are recognized when earned. Realized gains and losses are derived from the amortized cost of the security sold using the specific identification method. During the year ended December 31, 2017, the Company sold $24,796,000 of available for sale classified investment securities for $25,757,000 realizing a gain of $961,000. During the year ended December 31, 2016, the Company did not sell any investment securities. At December 31, 2017 and 2016, the Company did not have any securities classified as trading. The Company assesses other-than-temporary impairment (“OTTI”) based on whether it intends to sell a security or if it is likely that the Company would be required to sell the security before recovery of the amortized cost basis of the investment, which may be maturity. For debt securities, if we intend to sell the security or it is more likely than not that we will be required to sell the security before recovering its cost basis, the entire impairment loss would be recognized in earnings as an OTTI. If we do not intend to sell the security and it is not likely that we will be required to sell the security but we do not expect to recover the entire amortized cost basis of the security, only the portion of the impairment loss representing credit losses would be recognized in earnings. The credit loss on a security is measured as the difference between the amortized cost basis and the present value of the cash flows expected to be collected. Projected cash flows are discounted by the original or current effective interest rate depending on the nature of the security being measured for potential OTTI. The remaining impairment related to all other factors, the difference between the present value of the cash flows expected to be collected and fair value, is recognized as a charge to other comprehensive income (“OCI”). Impairment losses related to all other factors are presented as separate categories within OCI. The accretion of the amount recorded in OCI increases the carrying value of the investment and does not affect earnings. If there is an indication of additional credit losses the security is re-evaluated Restricted Equity Securities Restricted equity securities represent the Company’s investment in the stock of the Federal Home Loan Bank of San Francisco (“FHLB”) and are carried at par value, which reasonably approximates its fair value. While technically these are considered equity securities, there is no market for the FHLB stock. Therefore, the shares are considered as restricted investment securities. Management periodically evaluates FHLB stock for other-than-temporary impairment. Management’s determination of whether these investments are impaired is based on its assessment of the ultimate recoverability of cost rather than by recognizing temporary declines in value. The determination of whether a decline affects the ultimate recoverability of cost is influenced by criteria such as (1) the significance of any decline in net assets of the FHLB as compared to the capital stock amount for the FHLB and the length of time this situation has persisted, (2) commitments by the FHLB to make payments required by law or regulation and the level of such payments in relation to the operating performance of the FHLB, (3) the impact of legislative and regulatory changes on institutions and, accordingly, the customer base of the FHLB, and (4) the liquidity position of the FHLB. As a member of the FHLB system, the Bank is required to maintain a minimum level of investment in FHLB stock based on specific percentages of its outstanding mortgages, total assets, or FHLB advances. The Bank may request redemption at par value of any stock in excess of the minimum required investment. Stock redemptions are at the discretion of the FHLB. Loans Held for Sale Loans originated and intended for sale in the secondary market are carried at the lower of aggregate cost or fair value, as determined by aggregate outstanding commitments from investors of current investor yield requirements. Net unrealized losses are recognized through a valuation allowance by charges to noninterest income. Mortgage loans held for sale are generally sold with the mortgage servicing rights retained by the Company. Gains or losses on the sale of loans that are held for sale are recognized at the time of the sale and determined by the difference between net sale proceeds and the net book value of the loans less the estimated fair value of any retained mortgage servicing rights. Loans and Allowance for Loan Losses Loans originated by the Company, i.e., not purchased or acquired in a business combination, are referred to as originated loans. Originated loans that management has the intent and ability to hold for the foreseeable future or until maturity or payoff are reported at the principal amount outstanding, net of deferred loan fees and costs. Loan origination and commitment fees and certain direct loan origination costs are deferred, and the net amount is amortized as an adjustment of the related loan’s yield over the actual life of the loan. Originated loans on which the accrual of interest has been discontinued are designated as nonaccrual loans. Originated loans are placed in nonaccrual status when reasonable doubt exists as to the full, timely collection of interest or principal, or a loan becomes contractually past due by 90 days or more with respect to interest or principal and is not well secured and in the process of collection. When an originated loan is placed on nonaccrual status, all interest previously accrued but not collected is reversed. Income on such loans is then recognized only to the extent that cash is received and where the future collection of principal is probable. Interest accruals are resumed on such loans only when they are brought fully current with respect to interest and principal and when, in the judgment of Management, the loan is estimated to be fully collectible as to both principal and interest. An allowance for loan losses for originated loans is established through a provision for loan losses charged to expense. The allowance is maintained at a level which, in Management’s judgment, is adequate to absorb probable incurred credit losses inherent in the loan portfolio as of the balance sheet date. Originated loans and deposit related overdrafts are charged against the allowance for loan losses when Management believes that the collectability of the principal is unlikely or, with respect to consumer installment loans, according to an established delinquency schedule. The allowance is an amount that Management believes will be adequate to absorb probable incurred losses inherent in existing loans, based on evaluations of the collectability, impairment and prior loss experience of loans. The evaluations take into consideration such factors as changes in the nature and size of the portfolio, overall portfolio quality, loan concentrations, specific problem loans, and current economic conditions that may affect the borrower’s ability to pay. The Company defines an originated loan as impaired when it is probable the Company will be unable to collect all amounts due according to the original contractual terms of the loan agreement. Impaired originated loans are measured based on the present value of expected future cash flows discounted at the loan’s original effective interest rate. As a practical expedient, impairment may be measured based on the loan’s observable market price or the fair value of the collateral if the loan is collateral dependent. When the measure of the impaired loan is less than the recorded investment in the loan, the impairment is recorded through a specific reserve allocation within the allowance for loan losses. In situations related to originated loans where, for economic or legal reasons related to a borrower’s financial difficulties, the Company grants a concession for other than an insignificant period of time to the borrower that the Company would not otherwise consider, the related loan is classified as a troubled debt restructuring (TDR). The Company strives to identify borrowers in financial difficulty early and work with them to modify to more affordable terms before their loan reaches nonaccrual status. These modified terms may include rate reductions, principal forgiveness, payment forbearance and other actions intended to minimize the economic loss and to avoid foreclosure or repossession of the collateral. In cases where the Company grants the borrower new terms that result in the loan being classified as a TDR, the Company measures any impairment on the restructuring as noted above for impaired loans. TDR loans are classified as impaired until they are fully paid off or charged off. Loans that are in nonaccrual status at the time they become TDR loans, remain in nonaccrual status until the borrower demonstrates a sustained period of performance which the Company generally believes to be six consecutive months of payments, or equivalent. Otherwise, TDR loans are subject to the same nonaccrual and charge-off Credit risk is inherent in the business of lending. As a result, the Company maintains an allowance for loan losses to absorb probable incurred losses inherent in the Company’s originated loan portfolio. This is maintained through periodic charges to earnings. These charges are included in the Consolidated Statements of Income as provision for loan losses. All specifically identifiable and quantifiable losses are immediately charged off against the allowance. However, for a variety of reasons, not all losses are immediately known to the Company and, of those that are known, the full extent of the loss may not be quantifiable at that point in time. The balance of the Company’s allowance for originated loan losses is meant to be an estimate of these probable incurred losses inherent in the portfolio. The Company formally assesses the adequacy of the allowance for originated loan losses on a quarterly basis. Determination of the adequacy is based on ongoing assessments of the probable risk in the outstanding originated loan portfolio, and to a lesser extent the Company’s originated loan commitments. These assessments include the periodic re-grading re-graded Re-grading The Company’s method for assessing the appropriateness of the allowance for originated loan losses includes specific allowances for impaired originated loans, formula allowance factors for pools of credits, and allowances for changing environmental factors (e.g., interest rates, growth, economic conditions, etc.). Allowance factors for loan pools were based on historical loss experience by product type and prior risk rating. Loans purchased or acquired in a business combination are referred to as acquired loans. Acquired loans are valued as of the acquisition date in accordance with Financial Accounting Standards Board Accounting Standards Codification (“FASB ASC”) Topic 805, Business Combinations 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality 310-30, 310-30 310-30 Acquired loans that are not PCI loans are referred to as purchased not credit impaired (PNCI) loans. PNCI loans are accounted for under FASB ASC Topic 310-20, Receivables – Nonrefundable Fees and Other Costs, 310-20, Throughout these financial statements, and in particular in Note 4 and Note 5, when we refer to “Loans” or “Allowance for loan losses” we mean all categories of loans, including Originated, PNCI, PCI – cash basis, and PCI – other. When we are not referring to all categories of loans, we will indicate which we are referring to – Originated, PNCI, PCI – cash basis, or PCI – other. When referring to PNCI and PCI loans we use the terms “nonaccretable difference”, “accretable yield”, or “purchase discount”. Nonaccretable difference is the difference between undiscounted contractual cash flows due and undiscounted cash flows we expect to collect, or put another way, it is the undiscounted contractual cash flows we do not expect to collect. Accretable yield is the difference between undiscounted cash flows we expect to collect and the value at which we have recorded the loan on our financial statements. On the date of acquisition, all purchased loans are recorded on our consolidated financial statements at estimated fair value. Purchase discount is the difference between the estimated fair value of loans on the date of acquisition and the principal amount owed by the borrower, net of charge offs, on the date of acquisition. We may also refer to “discounts to principal balance of loans owed, net of charge-offs”. Discounts to principal balance of loans owed, net of charge-offs is the difference between principal balance of loans owed, net of charge-offs, and loans as recorded on our financial statements. Discounts to principal balance of loans owed, net of charge-offs arise from purchase discounts, and equal the purchase discount on the acquisition date. Loans are also categorized as “covered” or “noncovered”. Covered loans refer to loans covered by a Federal Deposit Insurance Corporation (“FDIC”) loss sharing agreement. Noncovered loans refer to loans not covered by a FDIC loss sharing agreement. Foreclosed Assets Foreclosed assets include assets acquired through, or in lieu of, loan foreclosure. Foreclosed assets are held for sale and are initially recorded at fair value less estimated costs to sell at the date of foreclosure, establishing a new cost basis. Physical possession of residential real estate property collateralizing a consumer mortgage loan occurs when legal title is obtained upon completion of foreclosure or when the borrower conveys all interest in the property to satisfy the loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. Any write-downs based on the asset’s fair value less costs to sell at the date of acquisition are charged to the allowance for loan and lease losses. Any recoveries based on the asset’s fair value less estimated costs to sell in excess of the recorded value of the loan at the date of acquisition are recorded to the allowance for loan and lease losses. These assets are subsequently accounted for at lower of cost or fair value less estimated costs to sell. If fair value declines subsequent to foreclosure, a valuation allowance is recorded through expense. Operating costs after acquisition are expensed. Revenue and expenses from operations and changes in the valuation allowance are included in other noninterest expense. Gain or loss on sale of foreclosed assets is included in noninterest income. Foreclosed assets that are not subject to a FDIC loss-share agreement are referred to as noncovered foreclosed assets. Foreclosed assets acquired through FDIC-assisted acquisitions that are subject to a FDIC loss-share agreement, and all assets acquired via foreclosure of covered loans are referred to as covered foreclosed assets. Covered foreclosed assets are reported exclusive of expected reimbursement cash flows from the FDIC. Foreclosed covered loan collateral is transferred into covered foreclosed assets at the loan’s carrying value, inclusive of the acquisition date fair value discount. Covered foreclosed assets are initially recorded at estimated fair value less estimated costs to sell on the acquisition date based on similar market comparable valuations less estimated selling costs. Any subsequent valuation adjustments due to declines in fair value will be charged to noninterest expense, and will be mostly offset by noninterest income representing the corresponding increase to the FDIC indemnification asset for the offsetting loss reimbursement amount. Any recoveries of previous valuation adjustments will be credited to noninterest expense with a corresponding charge to noninterest income for the portion of the recovery that is due to the FDIC. Premises and Equipment Land is carried at cost. Land improvements, buildings and equipment, including those acquired under capital lease, are stated at cost less accumulated depreciation and amortization. Depreciation and amortization expenses are computed using the straight-line method over the shorter of the estimated useful lives of the related assets or lease terms. Asset lives range from 3-10 15-40 Goodwill and Other Intangible Assets Goodwill represents the excess of costs over fair value of net assets of businesses acquired. Goodwill and other intangible assets acquired in a business combination and determined to have an indefinite useful life are not amortized, but instead tested for impairment at least annually. Intangible assets with estimable useful lives are amortized over their respective estimated useful lives to their estimated residual values, and reviewed for impairment. The Company has an identifiable intangible asset consisting of core deposit intangibles (CDI). CDI are amortized over their respective estimated useful lives, and reviewed for impairment. Impairment of Long-Lived Assets and Goodwill Long-lived assets, such as premises and equipment, and purchased intangibles subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its estimated future cash flows, an impairment charge is recognized by the amount by which the carrying amount of the asset exceeds the fair value of the asset. Assets to be disposed of would be separately presented in the balance sheet and reported at the lower of the carrying amount or fair value less costs to sell, and are no longer depreciated. The assets and liabilities of a disposed group classified as held for sale would be presented separately in the appropriate asset and liability sections of the consolidated balance sheet. As of December 31 of each year, goodwill is tested for impairment, and is tested for impairment more frequently if events and circumstances indicate that the asset might be impaired. An impairment loss is recognized to the extent that the carrying amount exceeds the asset’s fair value. This determination is made at the reporting unit level. The Company may choose to first assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If, after assessing the totality of events or circumstances, the Company determines it is not more likely than not that the fair value of a reporting unit is less than its carrying amount, then goodwill is deemed not to be impaired. However, if the Company concludes otherwise, or if the Company elected not to first assess qualitative factors, then the Company performs the first step of a two-step Mortgage Servicing Rights Mortgage servicing rights (MSR) represent the Company’s right to a future stream of cash flows based upon the contractual servicing fee associated with servicing mortgage loans. Our MSR arise from residential and commercial mortgage loans that we originate and sell, but retain the right to service the loans. The net gain from the retention of the servicing right is included in gain on sale of loans in noninterest income when the loan is sold. Fair value is based on market prices for comparable mortgage servicing contracts, when available, or alternatively, is based on a valuation model that calculates the present value of estimated future net servicing income. The valuation model incorporates assumptions that market participants would use in estimating future net servicing income, such as the cost to service, the discount rate, the custodial earnings rate, an inflation rate, ancillary income, prepayment speeds and default rates and losses. Servicing fees are recorded in noninterest income when earned. The Company accounts for MSR at fair value. The determination of fair value of our MSR requires management judgment because they are not actively traded. The determination of fair value for MSR requires valuation processes which combine the use of discounted cash flow models and extensive analysis of current market data to arrive at an estimate of fair value. The cash flow and prepayment assumptions used in our discounted cash flow model are based on empirical data drawn from the historical performance of our MSR, which we believe are consistent with assumptions used by market participants valuing similar MSR, and from data obtained on the performance of similar MSR. The key assumptions used in the valuation of MSR include mortgage prepayment speeds and the discount rate. These variables can, and generally will, change from quarter to quarter as market conditions and projected interest rates change. The key risks inherent with MSR are prepayment speed and changes in interest rates. The Company uses an independent third party to determine fair value of MSR. Indemnification Asset/Liability The Company accounts for amounts receivable or payable under its loss-share agreements entered into with the FDIC in connection with its purchase and assumption of certain assets and liabilities of Granite as indemnification assets in accordance with FASB ASC Topic 805, Business Combinations Reserve for Unfunded Commitments The reserve for unfunded commitments is established through a provision for losses – unfunded commitments charged to noninterest expense. The reserve for unfunded commitments is an amount that Management believes will be adequate to absorb probable losses inherent in existing commitments, including unused portions of revolving lines of credit and other loans, standby letters of credit, and unused deposit account overdraft privileges. The reserve for unfunded commitments is based on evaluations of the collectability, and prior loss experience of unfunded commitments. The evaluations take into consideration such factors as changes in the nature and size of the loan portfolio, overall loan portfolio quality, loan concentrations, specific problem loans and related unfunded commitments, and current economic conditions that may affect the borrower’s or depositor’s ability to pay. Low Income Housing Tax Credits The Company accounts for low income housing tax credits and the related qualified affordable housing projects using the proportional amortization method. Under the proportional amortization method, the Company amortizes the initial cost of the investment in proportion to the tax credits and other tax benefits received and recognizes the net investment performance in the income statement as a component of income tax expense (benefit). Upon entering into a qualified affordable housing project, the Company records, in other liabilities, the entire amount that it has agreed to invest in the project, and an equal amount, in other assets, representing its investment in the project. As the Company disburses cash to satisfy its investment obligation, other liabilities are reduced. Over time, as the tax credits and other tax benefits of the project are realized by the Company, the investment recorded in other assets is reduced using the proportional amortization method. Income Taxes The Company’s accounting for income taxes is based on an asset and liability approach. The Company recognizes the amount of taxes payable or refundable for the current year, and deferred tax assets and liabilities for the future tax consequences that have been recognized in its financial statements or tax returns. The measurement of tax assets and liabilities is based on the provisions of enacted tax laws. A valuation allowance, if needed, reduces deferred tax assets to the expected amount most likely to be realized. Realization of deferred tax assets is dependent upon the generation of a sufficient level of future taxable income and recoverable taxes paid in prior years. Although realization is not assured, management believes it is more likely than not that all of the deferred tax assets will be realized. Interest and/or penalties related to income taxes are reported as a component of noninterest income. Off-Balance In the ordinary course of business, the Company has entered into commitments to extend credit, including commitments under credit card arrangements, commercial letters of credit, and standby letters of credit. Such financial instruments are recorded when they are funded. Geographical Descriptions For the purpose of describing the geographical location of the Company’s loans, the Company has defined northern California as that area of California north of, and including, Stockton; central California as that area of the state south of Stockton, to and including, Bakersfield; and southern California as that area of the state south of Bakersfield. Reclassifications During the three months ended September 30, 2017, the Company changed its classification of 1 st nd non-owner 1-4 0.10%-0.20% total loans Recent Accounting Pronouncements FASB Accounting Standards Update (ASU) No.2014-09, Revenue from Contracts with Customers (Topic 606): 2014-09 2014-09 2014-09 2014-09 ASU 2014-09 FASB issued Accounting Standard Update (ASU) No. 2016-02 , Leases (Topic 842) ASU 2016-2, on-balance ASU 2016-02 FASB issued Accounting Standard Update (ASU) No. 2016-09 , Compensation – Stock Compensation (Topic 718). ASU 2016-09, ASU 2016-09 FASB issued ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326) 2016-13 2016-13, 2016-13 available-for-sale 2016-13 2016-13 2016-13 2016-13 one-time one-time FASB issued ASU No. 2016-18, Statement of Cash Flows - Restricted Cash (Topic 230). ASU 2016-18 beginning-of-period end-of-period ASU 2016-18 FASB issued ASU No. 2017-01, Business Combinations - Clarifying the Definition of a Business (Topic 805). ASU 2017-01 ASU 2017-01 ASU 2017-01 FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other: Simplifying the Test for Goodwill Impairment (Topic 350). 2017-04 ASU 2017-04 FASB issued ASU No. 2017-07, Compensation - Retirement Benefits (Topic 715). 2017-07 ASU 2017-07 FASB issued ASU 2017-08, Receivables - Nonrefundable Fees and Other Costs (Topic 310). ASU 2017-08 non-pooled ASU 2017-08 ASU 2017-08 FASB issued ASU 2017-09, Compensation - Stock Compensation (Topic 718). ASU 2017-09 ASU 2017-09, ASU 2017-09 FASB issued ASU 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220 ) . 2018-02 2018-02 2018-02

Business Combinations

Business Combinations	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Business Combinations	Note 2 – Business Combinations Proposed Merger with FNB Bancorp On December 11, 2017, the Company and FNB Bancorp, a California corporation (“FNBB”), entered into an Agreement and Plan of Merger and Reorganization (the “Merger Agreement”) pursuant to which FNBB will be merged with and into the Company, with the Company as the surviving corporation (the “Merger”). Management expects the acquisition to close in the second quarter of 2018, subject to the satisfaction of customary closing conditions, including regulatory and shareholder approvals. The Merger Agreement provides that immediately after the Merger, FNBB’s bank subsidiary, First National Bank of Northern California (“First National Bank”), will merge with and into the Company’s bank subsidiary, Tri Counties Bank, with Tri Counties Bank as the surviving bank (the “Bank Merger”). The Merger and Bank Merger are collectively referred to as the “Proposed Transaction.” The Merger Agreement provides that each share of FNBB common stock issued and outstanding immediately prior to the effective time of the Merger will be canceled and converted into the right to receive 0.98 shares of the Company’s common stock (the “Exchange Ratio”), with cash paid in lieu of fractional shares of the Company’s common stock. Based on the closing price of the Company’s common stock of $41.64 on December 8, 2017, the consideration value was $40.81 per share of FNBB common stock or approximately $315.3 million in aggregate. The value of the merger consideration will fluctuate until closing based on the value of the Company’s stock and subject to a trading collar in certain circumstances. Upon consummation of the Merger, the shareholders of FNBB will own approximately 24% of the combined company. The Merger Agreement includes a trading collar that could result in termination of the Merger Agreement or a change to the Exchange Ratio. First, The Company can elect to terminate the Merger Agreement if both (i) the average share price of the Company’s common stock for the 20 day period up to and including the fifth day prior to the closing date (the “Average Closing Share Price”) is greater than $49.78, which equals 120% of the average share price of the Company’s Stock for the 20 trading-day Upon consummation of the Merger, each outstanding and unexercised option to acquire shares of FNBB common stock held by FNBB’s employees and directors will be canceled and, in exchange, the holder of the option will be entitled to receive, whether or not the option is fully vested, a lump sum cash payment equal to the product of (1) the number of shares of FNBB common stock remaining under the option multiplied by (2) the Exchange Ratio multiplied by (3) the amount, if any, by which the Average Closing Share Price exceeds the exercise price of the option. The consummation of the Merger is subject to a number of conditions, which include: (i) the approval of the Merger Agreement by FNBB’s shareholders and the approval of the Merger Agreement and the issuance of shares of the Company common stock by the Company’s shareholders; (ii) as of the closing of the Merger, FNBB shall have tangible common equity of not less than $119.0 million, subject to credit for certain merger-related expenses and certain assumptions and adjustments that are set forth in the Merger Agreement; (iii) the receipt of all necessary regulatory approvals for the Proposed Transaction, without the imposition of conditions or requirements that the Company’s Board of Directors reasonably determines in good faith would, individually or in the aggregate, materially reduce the economic benefits of the Proposed Transaction; (iv) the absence of any regulation, judgment, decree, injunction or other order of a governmental authority which prohibits the consummation of the Proposed Transaction or which prohibits or makes illegal the consummation of the Proposed Transaction; (v) the effective registration of the shares of the Company’s Common Stock to be issued to FNBB’s shareholders with the Securities and Exchange Commission (the “SEC”) and the approval of such shares for listing on the Nasdaq Global Select Market; (vi) all representations and warranties made by the Company and FNBB in the Merger Agreement must remain true and correct, except for certain inaccuracies that would not have, or would not reasonably be expected to have, a material adverse effect; and (vii) the Company and FNBB must have performed their respective obligations under the Merger Agreement in all material respects. Acquisition of Three Bank Branches and Associated Deposits On March 18, 2016, the Bank completed its acquisition of three branch banking offices from Bank of America originally announced October 28, 2015. The acquired branches are located in Arcata, Eureka and Fortuna in Humboldt County on the North Coast of California, and have significant overlap compared to the Company’s then-existing Northern California customer base and branch locations. As a result, these branch acquisitions create potential cost savings and future growth potential. With the levels of capital at the time, the acquisitions fit well into the Company’s growth strategy. Also on March 18, 2016, the electronic customer service and other data processing systems of the acquired branches were converted into the Bank’s systems, and the effect of revenue and expenses from the operations of the acquired branches are included in the results of the Company. The Bank paid a premium of $3,204,000 for deposit relationships with balances of $161,231,000 and loans with balances of $289,000, and received cash of $159,520,000 from Bank of America. The assets acquired and liabilities assumed in the acquisition of these branches were accounted for in accordance with ASC 805 “Business Combinations,” using the acquisition method of accounting and were recorded at their estimated fair values on the March 18, 2016 acquisition date, and the results of operations of the acquired branches are included in the Company’s consolidated statements of income since that date. The excess of the fair value of consideration transferred over total identifiable net assets was recorded as goodwill. The goodwill arising from the acquisition consists largely of the synergies and economies of scale expected from combining the operations of the Company and the acquired branches. $849,000 of the goodwill is deductible for income tax purposes because the acquisition was accounted for as a purchase of assets and assumption of liabilities for tax purposes. The following table discloses the calculation of the fair value of consideration transferred, the total identifiable net assets acquired and the resulting goodwill relating to the acquisition of three branch banking offices and certain deposits from Bank of America on March 18, 2016: (in thousands) March 18, 2016 Fair value of consideration transferred: Cash consideration $ 3,204 Total fair value of consideration transferred 3,204 Asset acquired: Cash and cash equivalents 159,520 Loans 289 Premises and equipment 1,590 Core deposit intangible 2,046 Other assets 141 Total assets acquired 163,586 Liabilities assumed: Deposits 161,231 Total liabilities assumed 161,231 Total net assets acquired 2,355 Goodwill recognized $ 849 A summary of the cash paid and estimated fair value adjustments resulting in the goodwill recorded in the acquisition of three branch banking offices and certain deposits from Bank of America on March 18, 2016 are presented below: (in thousands) March 18, 2016 Cash paid $ 3,204 Cost basis net assets acquired — Fair value adjustments: Loans — Premises and Equipment (309 ) Core deposit intangible (2,046 ) Goodwill $ 849 As part of the acquisition of three branch banking offices from Bank of America, the Company performed a valuation of premises and equipment acquired. This valuation resulted in a $309,000 increase in the net book value of the land and buildings acquired, and was based on current appraisals of such land and buildings. The Company recognized a core deposit intangible of $2,046,000 related to the acquisition of the core deposits. The recorded core deposit intangibles represented approximately 1.50% of the core deposits acquired and will be amortized over their estimated useful lives of 7 years. A valuation of the time deposits acquired was also performed as of the acquisition date. Time deposits were split into similar pools based on size, type of time deposits, and maturity. A discounted cash flow analysis was performed on the pools based on current market rates currently paid on similar time deposits. The valuation resulted in no material fair value discount or premium, and none was recorded.

Investment Securities

Investment Securities	12 Months Ended
	Dec. 31, 2017
Investments Schedule [Abstract]
Investment Securities	Note 3 – Investment Securities The amortized cost and estimated fair values of investments in debt and equity securities are summarized in the following tables: December 31, 2017 Amortized Gross Gross Estimated (in thousands) Securities Available for Sale Obligations of U.S. government corporations and agencies $ 609,695 $ 695 $ (5,601 ) $ 604,789 Obligations of states and political subdivisions 121,597 1,888 (329 ) 123,156 Marketable equity securities 3,000 — (62 ) 2,938 Total securities available for sale $ 734,292 $ 2,583 $ (5,992 ) $ 730,883 Securities Held to Maturity Obligations of U.S. government corporations and agencies $ 500,271 $ 5,101 $ (1,889 ) $ 503,483 Obligations of states and political subdivisions 14,573 146 (37 ) 14,682 Total securities held to maturity $ 514,844 $ 5,247 $ (1,926 ) $ 518,165 December 31, 2016 Amortized Gross Gross Estimated (in thousands) Securities Available for Sale Obligations of U.S. government corporations and agencies $ 434,357 $ 1,949 $ (6,628 ) $ 429,678 Obligations of states and political subdivisions 121,746 267 (4,396 ) 117,617 Marketable equity securities 3,000 — (62 ) 2,938 Total securities available for sale $ 559,103 $ 2,216 $ (11,086 ) $ 550,233 Securities Held to Maturity Obligations of U.S. government corporations and agencies $ 587,982 $ 5,001 $ (4,199 ) $ 588,784 Obligations of states and political subdivisions 14,554 56 (191 ) 14,419 Total securities held to maturity $ 602,536 $ 5,057 $ (4,390 ) $ 603,203 During 2017 investment securities with cost basis of $24,796,000 were sold for $25,757,000, resulting in a gain of $961,000 on sale. No investment securities were sold during 2016. Investment securities totaling $2,000 were sold in 2015 resulting in no gain or loss on sale. Investment securities with an aggregate carrying value of $285,596,000 and $292,737,000 at December 31, 2017 and 2016, respectively, were pledged as collateral for specific borrowings, lines of credit and local agency deposits. The amortized cost and estimated fair value of debt securities at December 31, 2017 by contractual maturity are shown below. Actual maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. At December 31, 2017, obligations of U.S. government corporations and agencies with a cost basis totaling $1,109,966,000 consist almost entirely of residential real estate mortgage-backed securities whose contractual maturity, or principal repayment, will follow the repayment of the underlying mortgages. For purposes of the following table, the entire outstanding balance of these mortgage-backed securities issued by U.S. government corporations and agencies is categorized based on final maturity date. At December 31, 2017, the Company estimates the average remaining life of these mortgage-backed securities issued by U.S. government corporations and agencies to be approximately 5.9 years. Average remaining life is defined as the time span after which the principal balance has been reduced by half. Available for Sale Held to Maturity Investment Securities (In thousands) Amortized Estimated Amortized Estimated Due in one year $ 2 $ 2 — — Due after one year through five years 211 211 $ 1,207 $ 1,226 Due after five years through ten years 2,231 2,281 14,011 14,067 Due after ten years 731,848 728,389 499,626 502,872 Totals $ 734,292 $ 730,883 $ 514,844 $ 518,165 Gross unrealized losses on investment securities and the fair value of the related securities, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, were as follows: Less than 12 months 12 months or more Total December 31, 2017: Fair Unrealized Fair Unrealized Fair Unrealized (in thousands) Securities Available for Sale Obligations of U.S. government corporations and agencies $ 284,367 $ (2,176 ) $ 166,338 $ (3,425 ) $ 450,705 $ (5,601 ) Obligations of states and political subdivisions 4,904 (35 ) 17,085 (294 ) 21,989 (329 ) Marketable equity securities — — 2,938 (62 ) 2,938 (62 ) Total securities available-for-sale $ 289,271 $ (2,211 ) $ 186,361 $ (3,781 ) $ 475,632 $ (5,992 ) Securities Held to Maturity Obligations of U.S. government corporations and agencies $ 93,017 $ (567 ) $ 95,367 $ (1,322 ) $ 188,384 $ (1,889 ) Obligations of states and political subdivisions 1,488 (7 ) 2,637 (30 ) 4,125 (37 ) Total securities held-to-maturity $ 94,505 $ (574 ) $ 98,004 $ (1,352 ) $ 192,509 $ (1,926 ) Less than 12 months 12 months or more Total December 31, 2016: Fair Unrealized Fair Unrealized Fair Unrealized (in thousands) Securities Available for Sale Obligations of U.S. government corporations and agencies $ 370,389 $ (6,628 ) — — $ 370,389 $ (6,628 ) Obligations of states and political subdivisions 90,825 (4,396 ) — — 90,825 (4,396 ) Marketable equity securities 2,938 (62 ) — — 2,938 (62 ) Total securities available-for-sale $ 464,152 $ (11,086 ) — — $ 464,152 $ (11,086 ) Securities Held to Maturity Obligations of U.S. government corporations and agencies $ 280,497 $ (4,199 ) — — $ 280,497 $ (4,199 ) Obligations of states and political subdivisions 9,984 (191 ) — — 9,984 (191 ) Total securities held-to-maturity $ 290,481 $ (4,390 ) — — $ 290,481 $ (4,390 ) Obligations of U.S. government corporations and agencies: Unrealized losses on investments in obligations of U.S. government corporations and agencies are caused by interest rate increases. The contractual cash flows of these securities are guaranteed by U.S. Government Sponsored Entities (principally Fannie Mae and Freddie Mac). It is expected that the securities would not be settled at a price less than the amortized cost of the investment. Because the decline in fair value is attributable to changes in interest rates and not credit quality, and because the Company does not intend to sell and more likely than not will not be required to sell, these investments are not considered other-than-temporarily impaired. At December 31, 2017, 69 debt securities representing obligations of U.S. government corporations and agencies had unrealized losses with aggregate depreciation of 1.16% from the Company’s amortized cost basis. Obligations of states and political subdivisions: The unrealized losses on investments in obligations of states and political subdivisions were caused by increases in required yields by investors in these types of securities. It is expected that the securities would not be settled at a price less than the amortized cost of the investment. Because the decline in fair value is attributable to changes in interest rates and not credit quality, and because the Company does not intend to sell and more likely than not will not be required to sell, these investments are not considered other-than-temporarily impaired. At December 31, 2017, 29 debt securities representing obligations of states and political subdivisions had unrealized losses with aggregate depreciation of 1.38% from the Company’s amortized cost basis. Marketable equity securities: At December 31, 2017, marketable equity securities had unrealized losses representing aggregate depreciation of 2.07% from the Company’s amortized cost basis. Because the Company has the ability to hold these equity investment securities and management does not intend to sell and more likely than not will not be required to sell these securities prior to the recovery of value, management does not believe these securities to be other than temporarily impaired.

Loans

Loans	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Loans	Note 4 – Loans A summary of loan balances follows (in thousands): December 31, 2017 Originated PNCI PCI - PCI - Total Mortgage loans on real estate: Residential 1-4 $ 320,522 $ 63,519 — $ 1,385 $ 385,426 Commercial 1,690,510 215,823 — 8,563 1,914,896 Total mortgage loan on real estate 2,011,032 279,342 — 9,948 2,300,322 Consumer: Home equity lines of credit 269,942 16,248 2,069 429 288,688 Home equity loans 39,848 2,698 — 485 43,031 Other 22,859 2,251 — 45 25,155 Total consumer loans 332,649 21,197 2,069 959 356,874 Commercial 209,437 8,391 — 2,584 220,412 Construction: Residential 67,920 10 — — 67,930 Commercial 69,364 263 — — 69,627 Total construction 137,284 273 — — 137,557 Total loans, net of deferred loan fees and discounts $ 2,690,402 $ 309,203 $ 2,069 $ 13,491 $ 3,015,165 Total principal balance of loans owed, net of charge-offs $ 2,699,053 $ 316,238 $ 5,863 $ 17,318 $ 3,038,472 Unamortized net deferred loan fees (8,651 ) — — — (8,651 ) Discounts to principal balance of loans owed, net of charge-offs — (7,035 ) (3,794 ) (3,827 ) (14,656 ) Total loans, net of unamortized deferred loan fees and discounts $ 2,690,402 $ 309,203 $ 2,069 $ 13,491 $ 3,015,165 Noncovered loans $ 2,690,402 $ 309,203 $ 2,069 $ 13,491 $ 3,015,165 Covered loans — — — — — Total loans, net of unamortized deferred loan fees and discounts $ 2,690,402 $ 309,203 $ 2,069 $ 13,491 $ 3,015,165 Allowance for loan losses $ (29,122 ) $ (929 ) $ (17 ) $ (255 ) $ (30,323 ) A summary of loan balances follows (in thousands): December 31, 2016 Originated PNCI PCI - PCI - Total Mortgage loans on real estate: Residential 1-4 $ 284,539 $ 82,335 — $ 1,469 $ 368,343 Commercial 1,425,828 246,491 — 12,802 1,685,121 Total mortgage loan on real estate 1,710,367 328,826 — 14,271 2,053,464 Consumer: Home equity lines of credit 263,590 21,765 2,983 1,377 289,715 Home equity loans 40,736 3,764 — 1,682 46,182 Other 28,167 2,534 — 65 30,766 Total consumer loans 332,493 28,063 2,983 3,124 366,663 Commercial 200,735 12,321 — 3,991 217,047 Construction: Residential 54,613 141 — 675 55,429 Commercial 58,119 8,871 — — 66,990 Total construction 112,732 9,012 — 675 122,419 Total loans, net of deferred loan fees and discounts $ 2,356,327 $ 378,222 $ 2,983 $ 22,061 $ 2,759,593 Total principal balance of loans owed, net of charge-offs $ 2,363,243 $ 388,139 $ 8,280 $ 25,650 $ 2,785,312 Unamortized net deferred loan fees (6,916 ) — — — (6,916 ) Discounts to principal balance of loans owed, net of charge-offs — (9,917 ) (5,297 ) (3,589 ) (18,803 ) Total loans, net of unamortized deferred loan fees and discounts $ 2,356,327 $ 378,222 $ 2,983 $ 22,061 $ 2,759,593 Noncovered loans $ 2,356,327 $ 378,222 $ 2,983 $ 18,885 $ 2,756,417 Covered loans — — — 3,176 3,176 Total loans, net of unamortized deferred loan fees and discounts $ 2,356,327 $ 378,222 $ 2,983 $ 22,061 $ 2,759,593 Allowance for loan losses $ (28,141 ) $ (1,665 ) $ (17 ) $ (2,680 ) $ (32,503 ) The following is a summary of the change in accretable yield for PCI – other loans during the periods indicated (in thousands): Year ended December 31, 2017 2016 Change in accretable yield: Balance at beginning of period $ 10,348 $ 13,255 Accretion to interest income (2,809 ) (4,011 ) Reclassification (to) from nonaccretable difference (3,277 ) 1,104 Balance at end of period $ 4,262 $ 10,348

Allowance for Loan Losses

Allowance for Loan Losses	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Allowance for Loan Losses	Note 5 – Allowance for Loan Losses The following tables summarize the activity in the allowance for loan losses, and ending balance of loans, net of unearned fees for the periods indicated. Allowance for Loan Losses - Year Ended December 31, 2017 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Beginning balance $ 2,748 $ 11,517 $ 7,044 $ 2,644 — $ 622 $ 5,831 $ 1,417 $ 680 $ 32,503 Charge-offs (60 ) (186 ) (98 ) (332 ) — (1,186 ) (1,444 ) (1,104 ) — (4,410 ) Recoveries — 397 698 242 — 375 428 — 1 2,141 (Benefit) provision (371 ) (287 ) (1,844 ) (713 ) — 775 1,697 871 (39 ) 89 Ending balance $ 2,317 $ 11,441 $ 5,800 $ 1,841 — $ 586 $ 6,512 $ 1,184 $ 642 $ 30,323 Ending balance: Individ. evaluated for impairment $ 230 $ 30 $ 427 $ 107 — $ 57 $ 1,848 — — $ 2,699 Loans pooled for evaluation $ 1,932 $ 11,351 $ 5,356 $ 1,734 — $ 529 $ 4,624 $ 1,184 $ 642 $ 27,352 Loans acquired with deteriorated credit quality $ 155 $ 60 $ 17 — — — $ 40 — — $ 272 Loans, net of unearned fees – As of December 31, 2017 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Ending balance: Total loans $ 385,426 $ 1,914,896 $ 288,688 $ 43,031 — $ 25,155 $ 220,412 $ 67,930 $ 69,627 $ 3,015,165 Individ. evaluated for impairment $ 5,298 $ 13,911 $ 2,688 $ 1,470 — $ 257 $ 4,470 $ 140 — $ 28,234 Loans pooled for evaluation $ 378,743 $ 1,892,422 $ 283,502 $ 41,076 — $ 24,853 $ 213,358 $ 67,790 $ 69,627 $ 2,971,371 Loans acquired with deteriorated credit quality $ 1,385 $ 8,563 $ 2,498 $ 485 — $ 45 $ 2,584 — — $ 15,560 Allowance for Loan Losses - Year Ended December 31, 2016 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Beginning balance $ 2,896 $ 11,015 $ 11,253 $ 3,177 — $ 688 $ 5,271 $ 899 $ 812 $ 36,011 Charge-offs (321 ) (827 ) (585 ) (219 ) — (823 ) (455 ) — — (3,230 ) Recoveries 880 920 2,317 590 — 449 404 54 78 5,692 (Benefit) provision (707 ) 409 (5,941 ) (904 ) — 308 611 464 (210 ) (5,970 ) Ending balance $ 2,748 $ 11,517 $ 7,044 $ 2,644 — $ 622 $ 5,831 $ 1,417 $ 680 $ 32,503 Ending balance: Individ. evaluated for impairment $ 258 $ 4 $ 411 $ 215 — $ 28 $ 1,130 — — $ 2,046 Loans pooled for evaluation $ 2,304 $ 10,064 $ 6,616 $ 2,365 — $ 594 $ 3,765 $ 1,372 $ 680 $ 27,760 Loans acquired with deteriorated credit quality $ 186 $ 1,449 $ 17 $ 64 — — $ 936 $ 45 — $ 2,697 Loans, net of unearned fees – As of December 31, 2016 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Ending balance: Total loans $ 368,343 $ 1,685,121 $ 289,715 $ 46,182 — $ 30,766 $ 217,047 $ 55,429 $ 66,990 $ 2,759,593 Individ. evaluated for impairment $ 4,094 $ 15,081 $ 3,196 $ 1,508 — $ 154 $ 4,096 $ 11 — $ 28,140 Loans pooled for evaluation $ 362,780 $ 1,657,238 $ 282,159 $ 42,992 — $ 30,547 $ 208,960 $ 54,743 $ 66,990 $ 2,706,409 Loans acquired with deteriorated credit quality $ 1,469 $ 12,802 $ 4,360 $ 1,682 — $ 65 $ 3,991 $ 675 — $ 25,044 Allowance for Loan Losses - Year Ended December 31, 2015 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Beginning balance $ 3,086 $ 9,227 $ 15,676 $ 1,797 $ 9 $ 719 $ 4,226 $ 1,434 $ 411 $ 36,585 Charge-offs (224 ) — (694 ) (242 ) (4 ) (972 ) (680 ) — — (2,816 ) Recoveries 204 243 666 252 42 500 677 1,728 140 4,452 (Benefit) provision (170 ) 1,545 (4,395 ) 1,370 (47 ) 441 1,048 (2,263 ) 261 (2,210 ) Ending balance $ 2,896 $ 11,015 $ 11,253 $ 3,177 — $ 688 $ 5,271 $ 899 $ 812 $ 36,011 Ending balance: Individ. evaluated for impairment $ 335 $ 396 $ 605 $ 294 — $ 74 $ 1,187 — — $ 2,891 Loans pooled for evaluation $ 2,501 $ 9,167 $ 10,423 $ 2,883 — $ 614 $ 2,983 $ 844 $ 812 $ 30,227 Loans acquired with deteriorated credit quality $ 60 $ 1,452 $ 225 — — — $ 1,101 $ 55 — $ 2,893 Loans, net of unearned fees – As of December 31, 2015 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Ending balance: Total loans $ 314,265 $ 1,497,567 $ 322,492 $ 40,362 — $ 32,429 $ 194,913 $ 46,135 $ 74,774 $ 2,522,937 Individ. evaluated for impairment $ 6,767 $ 32,407 $ 5,747 $ 1,731 — $ 288 $ 2,671 $ 4 $ 490 $ 50,105 Loans pooled for evaluation $ 305,353 $ 1,442,100 $ 309,007 $ 37,004 — $ 32,077 $ 187,393 $ 45,410 $ 74,284 $ 2,432,628 Loans acquired with deteriorated credit quality $ 2,145 $ 23,060 $ 7,738 $ 1,627 — $ 64 $ 4,849 $ 721 — $ 40,204 As part of the on-going (iii) non-performing The Company utilizes a risk grading system to assign a risk grade to each of its loans. Loans are graded on a scale ranging from Pass to Loss. A description of the general characteristics of the risk grades is as follows: • Pass • Special Mention • Substandard • Doubtful • Loss The following tables present ending loan balances by loan category and risk grade for the periods indicated: Credit Quality Indicators – As of December 31, 2017 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Originated loans: Pass $ 315,120 $ 1,649,333 $ 265,345 $ 37,428 — $ 22,432 $ 195,208 $ 67,813 $ 64,492 $ 2,617,171 Special mention 2,234 18,434 2,558 800 — 272 9,492 — 4,872 38,662 Substandard 3,168 22,743 2,039 1,620 — 155 4,737 107 — 34,569 Loss — — — — — — — — — — Total originated $ 320,522 $ 1,690,510 $ 269,942 $ 39,848 — $ 22,859 $ 209,437 $ 67,920 $ 69,364 $ 2,690,402 PNCI loans: Pass $ 61,411 $ 203,751 $ 14,866 $ 2,433 — $ 2,207 $ 8,390 $ 10 $ 263 $ 293,331 Special mention 218 11,513 450 188 — 38 1 — — 12,408 Substandard 1,890 559 932 77 — 6 — — — 3,464 Loss — — — — — — — — — — Total PNCI $ 63,519 $ 215,823 $ 16,248 $ 2,698 — $ 2,251 $ 8,391 $ 10 $ 263 $ 309,203 PCI loans $ 1,385 $ 8,563 $ 2,498 $ 485 — $ 45 $ 2,584 — — $ 15,560 Total loans $ 385,426 $ 1,914,896 $ 288,688 $ 43,031 — 25,155 $ 220,412 $ 67,930 $ 69,627 $ 3,015,165 Credit Quality Indicators – As of December 31, 2016 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Originated loans: Pass $ 278,635 $ 1,399,936 $ 258,024 $ 37,844 — $ 27,542 $ 190,902 $ 54,602 $ 57,808 $ 2,305,293 Special mention 2,992 14,341 2,518 891 — 385 6,133 — 311 27,571 Substandard 2,912 11,551 3,048 2,001 — 240 3,700 11 — 23,463 Loss — — — — — — — — — — Total originated $ 284,539 $ 1,425,828 $ 263,590 $ 40,736 — $ 28,167 $ 200,735 $ 54,613 $ 58,119 $ 2,356,327 PNCI loans: Pass $ 79,000 $ 233,326 $ 20,442 $ 3,506 — $ 2,437 $ 12,320 $ 141 $ 8,871 $ 360,043 Special mention 1,849 5,925 509 173 — 92 1 — — 8,549 Substandard 1,486 7,240 814 85 — 5 — — — 9,630 Loss — — — — — — — — — — Total PNCI $ 82,335 $ 246,491 $ 21,765 $ 3,764 — $ 2,534 $ 12,321 $ 141 $ 8,871 $ 378,222 PCI loans $ 1,469 $ 12,802 $ 4,360 $ 1,682 — $ 65 $ 3,991 $ 675 — $ 25,044 Total loans $ 368,343 $ 1,685,121 $ 289,715 $ 46,182 — $ 30,766 $ 217,047 $ 55,429 $ 66,990 $ 2,759,593 Consumer loans, whether unsecured or secured by real estate, automobiles, or other personal property, are susceptible to three primary risks; non-payment non-payment Problem consumer loans are generally identified by payment history of the borrower (delinquency). The Bank manages its consumer loan portfolios by monitoring delinquency and contacting borrowers to encourage repayment, suggest modifications if appropriate, and, when continued scheduled payments become unrealistic, initiate repossession or foreclosure through appropriate channels. Collateral values may be determined by appraisals obtained through Bank approved, licensed appraisers, qualified independent third parties, public value information (blue book values for autos), sales invoices, or other appropriate means. Appropriate valuations are obtained at initiation of the credit and periodically (every 3-12 Commercial real estate loans generally fall into two categories, owner-occupied and non-owner non-owner Construction loans, whether owner occupied or non-owner Problem C&I loans are generally identified by periodic review of financial information which may include financial statements, tax returns, rent rolls and payment history of the borrower (delinquency). Based on this information the Bank may decide to take any of several courses of action including demand for repayment, additional collateral or guarantors, and, when repayment becomes unlikely through borrower’s income and cash flow, repossession or foreclosure of the underlying collateral. Collateral values may be determined by appraisals obtained through Bank approved, licensed appraisers, qualified independent third parties, public value information (blue book values for autos), sales invoices, or other appropriate means. Appropriate valuations are obtained at initiation of the credit and periodically (every 3-12 Once a loan becomes delinquent and repayment becomes questionable, a Bank collection officer will address collateral shortfalls with the borrower and attempt to obtain additional collateral. If this is not forthcoming and payment in full is unlikely, the Bank will estimate its probable loss, using a recent valuation as appropriate to the underlying collateral less estimated costs of sale, and charge the loan down to the estimated net realizable amount. Depending on the length of time until ultimate collection, the Bank may revalue the underlying collateral and take additional charge-offs as warranted. Revaluations may occur as often as every 3-12 The following table shows the ending balance of current, past due, and nonaccrual originated loans by loan category as of the date indicated: Analysis of Past Due and Nonaccrual Originated Loans – As of December 31, 2017 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Originated loan balance: Past due: 30-59 Days $ 1,740 $ 158 $ 528 $ 511 — $ 56 $ 956 $ 34 — $ 3,983 60-89 Days 510 987 48 107 — 36 738 — — 2,426 > 90 Days 243 — 372 373 — 3 1,527 — — 2,518 Total past due $ 2,493 $ 1,145 $ 948 $ 991 — $ 95 $ 3,221 $ 34 — $ 8,927 Current 318,029 1,689,365 268,994 38,857 — 22,764 206,216 67,886 $ 69,364 2,681,475 Total orig. loans $ 320,522 $ 1,690,510 $ 269,942 $ 39,848 — $ 22,859 $ 209,437 $ 67,920 $ 69,364 $ 2,690,402 > 90 Days and still accruing — — — — — — — — — — Nonaccrual loans $ 1,725 $ 8,144 $ 811 $ 1,106 — $ 7 $ 3,669 — — $ 15,462 The following table shows the ending balance of current, past due, and nonaccrual PNCI loans by loan category as of the date indicated: Analysis of Past Due and Nonaccrual PNCI Loans – As of December 31, 2017 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total PNCI loan balance: Past due: 30-59 Days $ 1,495 $ 70 $ 298 $ 30 — $ 6 — — — $ 1,899 60-89 Days 90 — 228 — — 26 — — — 344 > 90 Days 109 — 330 — — — — — — 439 Total past due $ 1,694 $ 70 $ 856 $ 30 — $ 32 — — — $ 2,682 Current 61,825 215,753 15,392 2,668 — 2,219 $ 8,391 $ 10 $ 263 306,521 Total PNCI loans $ 63,519 $ 215,823 $ 16,248 $ 2,698 — $ 2,251 $ 8,391 $ 10 $ 263 $ 309,203 > 90 Days and still accruing $ 81 — $ 200 — — — — — — $ 281 Nonaccrual loans $ 1,012 — $ 402 $ 44 — $ 5 — — — $ 1,463 The following table shows the ending balance of current, past due, and nonaccrual originated loans by loan category as of the date indicated: Analysis of Past Due and Nonaccrual Originated Loans – As of December 31, 2016 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Originated loan balance: Past due: 30-59 $ 552 $ 317 $ 754 $ 646 — $ 16 $ 1,148 $ 921 — $ 4,354 60-89 269 1,387 — 395 — 30 84 — $ 421 2,586 > 90 Days — 216 687 184 — 15 634 11 — 1,747 Total past due $ 821 $ 1,920 $ 1,441 $ 1,225 — $ 61 $ 1,866 $ 932 $ 421 $ 8,687 Current 283,718 1,423,908 262,149 39,511 — 28,106 198,869 53,681 57,698 2,347,640 Total orig. loans $ 284,539 $ 1,425,828 $ 263,590 $ 40,736 — $ 28,167 $ 200,735 $ 54,613 $ 58,119 $ 2,356,327 > 90 Days and still accruing — — — — — — — — — — Nonaccrual loans $ 255 $ 7,651 $ 1,211 $ 803 — $ 33 $ 2,930 $ 11 — $ 12,894 The following table shows the ending balance of current, past due, and nonaccrual PNCI loans by loan category as of the date indicated: Analysis of Past Due and Nonaccrual PNCI Loans – As of December 31, 2016 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total PNCI loan balance: Past due: 30-59 $ 1,510 $ 73 $ 274 $ 39 — — — — — $ 1,896 60-89 — — — — — — — — — — > 90 Days 21 81 589 13 — — — — — 704 Total past due $ 1,531 $ 154 $ 863 $ 52 — — — — — $ 2,600 Current 80,804 246,337 20,902 3,712 — $ 2,534 $ 12,321 $ 141 $ 8,871 375,622 Total PNCI loans $ 82,335 $ 246,491 $ 21,765 $ 3,764 — $ 2,534 $ 12,321 $ 141 $ 8,871 $ 378,222 > 90 Days and still accruing — — — — — — — — — — Nonaccrual loans $ 194 $ 1,826 $ 742 $ 67 — $ 5 — — — $ 2,834 Impaired originated loans are those where management has concluded that it is probable that the borrower will be unable to pay all amounts due under the contractual terms. The following tables show the recorded investment (financial statement balance), unpaid principal balance, average recorded investment, and interest income recognized for impaired Originated and PNCI loans, segregated by those with no related allowance recorded and those with an allowance recorded for the periods indicated. Impaired Originated Loans – As of December 31, 2017 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total With no related allowance recorded: Recorded investment $ 2,058 $ 13,101 $ 1,093 $ 1,107 — $ 4 $ 575 $ 140 — $ 18,078 Unpaid principal $ 2,109 $ 13,360 $ 1,175 $ 1,429 — $ 52 $ 585 $ 140 — $ 18,850 Average recorded Investment $ 1,875 $ 13,123 $ 1,287 $ 852 — $ 10 $ 668 $ 76 — $ 17,891 Interest income Recognized $ 85 $ 609 $ 39 $ 14 — — $ 18 $ 9 — $ 774 With an allowance recorded: Recorded investment $ 1,881 $ 810 $ 401 $ 198 — $ 3 $ 3,895 — — $ 7,188 Unpaid principal $ 1,914 $ 826 $ 406 $ 198 — $ 3 $ 3,981 — — $ 7,328 Related allowance $ 230 $ 30 $ 111 $ 10 — $ 3 $ 1,848 — — $ 2,232 Average recorded Investment $ 1,626 $ 728 $ 415 $ 341 — $ 10 $ 3,615 — — $ 6,735 Interest income Recognized $ 58 $ 36 $ 8 $ 10 — — $ 166 — — $ 278 Impaired PNCI Loans – As of December 31, 2017 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total With no related allowance recorded: Recorded investment $ 1,359 — $ 591 $ 44 — — — — — $ 1,994 Unpaid principal $ 1,404 — $ 612 $ 57 — — — — — $ 2,073 Average recorded Investment $ 911 $ 913 $ 663 $ 56 — $ 2 — — — $ 2,545 Interest income Recognized $ 24 — $ 22 — — — — — — $ 46 With an allowance recorded: Recorded investment — — $ 603 $ 121 — $ 250 — — — $ 974 Unpaid principal — — $ 604 $ 121 — $ 250 — — — $ 975 Related allowance — — $ 316 $ 97 — $ 54 — — — $ 467 Average recorded Investment $ 130 $ 66 $ 577 $ 61 — $ 184 — — — $ 1,018 Interest income Recognized — — $ 26 $ 6 — $ 11 — — — $ 43 Impaired Originated Loans – As of December 31, 2016 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total With no related allowance recorded: Recorded investment $ 1,820 $ 12,898 $ 1,480 $ 715 — $ 15 $ 762 $ 11 — $ 17,701 Unpaid principal $ 1,829 $ 13,145 $ 1,561 $ 1,135 — $ 29 $ 926 $ 16 — $ 18,641 Average recorded Investment $ 2,853 $ 20,003 $ 2,221 $ 831 $ 1 $ 16 $ 669 $ 7 — $ 26,601 Interest income Recognized $ 92 $ 570 $ 40 $ 6 — $ 1 $ 48 — — $ 757 With an allowance recorded: Recorded investment $ 1,551 $ 357 $ 430 $ 594 — $ 19 $ 3,334 — — $ 6,285 Unpaid principal $ 1,552 $ 358 $ 440 $ 595 — $ 19 $ 3,385 — — $ 6,349 Related allowance $ 180 $ 4 $ 110 $ 107 — $ 13 $ 1,130 — — $ 1,544 Average recorded Investment $ 1,779 $ 888 $ 1,076 $ 634 — $ 9 $ 2,714 — — $ 7,100 Interest income Recognized $ 65 $ 22 $ 9 $ 31 — $ 2 $ 77 — — $ 206 Impaired PNCI Loans – As of December 31, 2016 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total With no related allowance recorded: Recorded investment $ 463 $ 1,826 $ 735 $ 67 — $ 3 — — — $ 3,094 Unpaid principal $ 486 $ 2,031 $ 746 $ 74 — $ 4 — — — $ 3,341 Average recorded Investment $ 669 $ 1,479 $ 594 $ 69 — $ 18 $ 1 — $ 245 $ 3,075 Interest income Recognized $ 7 — $ 9 $ 1 — — — — — $ 17 With an allowance recorded: Recorded investment $ 259 — $ 551 $ 132 — $ 118 — — — $ 1,060 Unpaid principal $ 259 — $ 551 $ 132 — $ 118 — — — $ 1,060 Related allowance $ 79 — $ 300 $ 108 — $ 15 — — — $ 502 Average recorded Investment $ 130 $ 1,374 $ 579 $ 85 — $ 176 — — — $ 2,344 Interest income Recognized $ 10 — $ 27 $ 7 — $ 5 — — — $ 49 At December 31, 2017, $12,517,000 of Originated loans were TDRs and classified as impaired. The Company had obligations to lend $1,000 of additional funds on these TDRs as of December 31, 2017. At December 31, 2017, $1,352,000 of PNCI loans were TDRs and classified as impaired. The Company had no obligations to lend additional funds on these TDRs as of December 31, 2017. At December 31, 2016, $12,371,000 of Originated loans were TDRs and classified as impaired. The Company had obligations to lend $25,000 of additional funds on these TDRs as of December 31, 2016. At December 31, 2016, $1,324,000 of PNCI loans were TDRs and classified as impaired. The Company had no obligations to lend additional funds on these TDRs as of December 31, 2016. At December 31, 2015, $29,269,000 of Originated loans were TDRs and classified as impaired. The Company had obligations to lend $35,000 of additional funds on these TDRs as of December 31, 2015. At December 31, 2015, $1,396,000 of PNCI loans were TDRs and classified as impaired. The Company had no obligations to lend additional funds on these TDRs as of December 31, 2015. The following tables show certain information regarding Troubled Debt Restructurings (TDRs) that occurred during the periods indicated: TDR Information for the Year Ended December 31, 2017 RE Mortgage Home Equity Auto Other Construction (dollars in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Number 1 8 3 1 — 1 11 1 — 26 Pre-mod $ 939 $ 3,721 $ 187 $ 252 — $ 14 $ 1,854 $ 144 — $ 7,111 Post-mod $ 939 $ 3,695 $ 187 $ 252 — $ 14 $ 1,747 $ 144 — $ 6,978 Financial impact due to TDR taken as additional provision $ 169 $ (111 ) $ 27 — — $ 11 $ 37 — — $ 133 Number that defaulted during the period 2 1 1 1 — — — — — 5 Recorded investment of TDRs that subsequently defaulted during the 12 month period after modification $ 223 $ 219 $ 127 $ 55 — — — — — $ 624 Financial impact due to the default of previous TDR taken as charge-offs or additional provisions — — $ (5 ) — — — — — — $ (5 ) TDR Information for the Year Ended December 31, 2016 RE Mortgage Home Equity Auto Other Construction (dollars in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Number 3 5 9 1 — 2 4 — — 24 Pre-mod $ 650 $ 423 $ 707 $ 105 — $ 27 $ 77 — — $ 1,989 Post-mod $ 656 $ 461 $ 709 $ 105 — $ 27 $ 77 — — $ 2,035 Financial impact due to TDR taken as additional provision $ 50 $ 46 $ 205 — — $ 2 $ 23 — — $ 326 Number that defaulted during the period 2 — 1 — — — — — — 3 Recorded investment of TDRs that subsequently defaulted during the 12 month period after modification $ 101 — $ 229 — — — — — — $ 330 Financial impact due to the default of previous TDR taken as charge-offs or additional provisions — — — — — — — — — — TDR Information for the Year Ended December 31, 2015 RE Mortgage Home Equity Auto Other Construction (dollars in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Number 4 5 2 2 — 2 8 — — 23 Pre-mod outstanding principal balance $ 800 $ 1,518 $ 301 $ 315 — $ 89 $ 956 — — $ 3,979 Post-mod outstanding principal balance $ 801 $ 1,517 $ 301 $ 321 — $ 89 $ 944 — — $ 3,973 Financial impact due to TDR taken as additional provision $ 8 $ (5 ) — $ 38 $ 5 $ 405 — — $ 451 Number that defaulted during the period 4 2 3 1 — — — — — 10 Recorded investment of TDRs that subsequently defaulted during the 12 month period after modification $ 221 $ 280 $ 182 $ 53 — — — — — $ 736 Financial impact due to the default of previous TDR taken as charge-offs or additional provisions — — — $ (9 ) — — — — — $ (9 ) Modifications classified as Troubled Debt Restructurings can include one or a combination of the following: rate modifications, term extensions, interest only modifications, either temporary or long-term, payment modifications, and collateral substitutions/additions. For all new Troubled Debt Restructurings, an impairment analysis is conducted. If the loan is determined to be collateral dependent, any additional amount of impairment will be calculated based on the difference between estimated collectible value and the current carrying balance of the loan. This difference could result in an increased provision and is typically charged off. If the asset is determined not to be collateral dependent, the impairment is measured on the net present value difference between the expected cash flows of the restructured loan and the cash flows which would have been received under the original terms. The effect of this could result in a requirement for additional provision to the reserve. The effect of these required provisions for the period are indicated above. Typically if a TDR defaults during the period, the loan is then considered collateral dependent and, if it was not already considered collateral dependent, an appropriate provision will be reserved or charge will be taken. The additional provisions required resulting from default of previously modified TDR’s are noted above.

Foreclosed Assets

Foreclosed Assets	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Foreclosed Assets	Note 6 – Foreclosed Assets A summary of the activity in the balance of foreclosed assets follows (dollars in thousands): Year ended December 31, 2017 Year ended December 31, 2016 Noncovered Covered Total Noncovered Covered Total Beginning balance, net $ 3,763 $ 223 $ 3,986 $ 5,369 — $ 5,369 Additions/transfers from loans 1,563 — 1,563 2,282 $ 223 2,505 Dispositions/sales (1,938 ) $ (223 ) (2,161 ) (3,748 ) — (3,748 ) Valuation adjustments (162 ) — (162 ) (140 ) — (140 ) Ending balance, net $ 3,226 — $ 3,226 $ 3,763 $ 223 $ 3,986 Ending valuation allowance $ (200 ) — $ (200 ) $ (314 ) — $ (314 ) Ending number of foreclosed assets 16 — 16 14 1 15 Proceeds from sale of foreclosed assets $ 2,656 $ 216 $ 2,872 $ 4,010 — $ 4,010 Gain on sale of foreclosed assets $ 718 $ (7 ) $ 711 $ 262 — $ 262 At December 31, 2017, the balance of real estate owned includes $1,186,000 of foreclosed residential real estate properties recorded as a result of obtaining physical possession of the property. At December 31, 2017, the recorded investment of consumer mortgage loans secured by residential real estate properties for which formal foreclosure proceedings are underway is $178,000.

Premises and Equipment

Premises and Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Premises and Equipment	Note 7 – Premises and Equipment Premises and equipment were comprised of: December 31, December 31, (In thousands) Land & land improvements $ 9,959 $ 9,522 Buildings 50,340 42,345 Furniture and equipment 35,939 31,428 96,238 83,295 Less: Accumulated depreciation (40,644 ) (37,412 ) 55,594 45,883 Construction in progress 2,148 2,523 Total premises and equipment $ 57,742 $ 48,406 Depreciation expense for premises and equipment amounted to $5,686,000, $5,314,000, and $5,043,000 in 2017, 2016, and 2015, respectively.

Cash Value of Life Insurance

Cash Value of Life Insurance	12 Months Ended
	Dec. 31, 2017
Investments, All Other Investments [Abstract]
Cash Value of Life Insurance	Note 8 – Cash Value of Life Insurance A summary of the activity in the balance of cash value of life insurance follows (dollars in thousands): Year ended December 31, 2017 2016 Beginning balance $ 95,912 $ 94,560 Increase in cash value of life insurance 2,685 2,717 Death benefit receivable in excess of cash value 108 238 Death benefit receivable (922 ) (1,603 ) Ending balance $ 97,783 $ 95,912 End of period death benefit $ 165,587 $ 165,669 Number of policies owned 182 185 Insurance companies used 14 14 Current and former employees and directors covered 57 58 As of December 31, 2017, the Bank was the owner and beneficiary of 182 life insurance policies, issued by 14 life insurance companies, covering 57 current and former employees and directors. These life insurance policies are recorded on the Company’s financial statements at their reported cash (surrender) values. As a result of current tax law and the nature of these policies, the Bank records any increase in cash value of these policies as nontaxable noninterest income. If the Bank decided to surrender any of the policies prior to the death of the insured, such surrender may result in a tax expense related to the life-to-date

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Note 9 – Goodwill and Other Intangible Assets The following table summarizes the Company’s goodwill intangible as of the dates indicated: December 31, December 31, (Dollar in Thousands) 2017 Additions Reductions 2016 Goodwill $ 64,311 — — $ 64,311 The following table summarizes the Company’s core deposit intangibles as of the dates indicated: December 31, Reductions/ Fully December 31, (Dollar in Thousands) 2017 Additions Amortization Depreciated 2016 Core deposit intangibles $ 9,558 — — $ (562 ) $ 10,120 Accumulated amortization (4,384 ) — $ (1,389 ) $ 562 (3,557 ) Core deposit intangibles, net $ 5,174 — $ (1,389 ) — $ 6,563 The Company recorded additions to its CDI of $2,046,000 in conjunction with the acquisition of three branch offices from Bank of America on March 18, 2016, $6,614,000 in conjunction with the North Valley Bancorp acquisition on October 3, 2014, $898,000 in conjunction with the Citizens acquisition on September 23, 2011, and $562,000 in conjunction with the Granite acquisition on May 28, 2010. The following table summarizes the Company’s estimated core deposit intangible amortization (dollars in thousands): Estimated Core Deposit Years Ended Intangible Amortization 2018 $ 1,324 2019 1,228 2020 1,228 2021 969 2022 280 Thereafter 145

Mortgage Servicing Rights

Mortgage Servicing Rights	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Mortgage Servicing Rights	Note 10 – Mortgage Servicing Rights The following tables summarize the activity in, and the main assumptions we used to determine the fair value of mortgage servicing rights for the periods indicated (dollars in thousands): Years ended December 31, 2017 2016 2015 Balance at beginning of period $ 6,595 $ 7,618 $ 7,378 Acquisition — — — Originations 810 1,161 941 Change in fair value (718 ) (2,184 ) (701 ) Balance at end of period $ 6,687 $ 6,595 $ 7,618 Contractually specified servicing fees, late fees and ancillary fees earned $ 2,076 $ 2,065 $ 2,164 Balance of loans serviced at: Beginning of period $ 816,623 $ 817,917 $ 840,288 End of period $ 811,065 $ 816,623 $ 817,917 Weighted-average prepayment speed (CPR) 8.9 % 8.8 % 9.8 % Weighted-average discount rate 13.0 % 14.0 % 10.0 % The changes in fair value of MSRs during 2017 were primarily due to changes in investor required rate of return, or discount rate, of the MSRs. The changes in fair value of MSRs during 2016 were primarily due to changes in principal balances, changes in mortgage prepayment speeds, and changes in investor required rate of return, or discount rate, of the MSRs. The changes in fair value of MSRs that occurred during 2015 were primarily due to changes in principal balances and changes in estimate life of the MSRs.

Indemnification Asset

Indemnification Asset	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Indemnification Asset	Note 11 – Indemnification Asset A summary of the activity in the balance of indemnification asset (liability) included in other assets is follows (in thousands): Year ended December 31, 2017 2016 2015 Beginning balance $ (744 ) $ (521 ) $ (349 ) Effect of actual covered losses (recoveries) and increase (decrease) in estimated future covered losses (192 ) (412 ) (93 ) Change in estimated “true up” liability (32 ) (86 ) (71 ) Reimbursable expenses, net — 2 4 Payments made (received) 256 273 (12 ) Gain on termination of loss share agreement 712 — — Ending balance — $ (744 ) $ (521 ) Amount of indemnification asset (liability) recorded in other assets — $ (60 ) $ 77 Amount of indemnification liability recorded in other liabilities — (684 ) (598 ) Ending balance — $ (744 ) $ (521 ) During May 2015, the indemnification portion of the Company’s agreement with the FDIC related to the Company’s acquisition of certain nonresidential real estate loans of Granite in May 2010 expired. The indemnification portion of the Company’s agreement with the FDIC related to the Company’s acquisition of certain residential real estate loans of Granite in May 2010 was set to expire in May 2018. The agreement specified that recoveries of losses that are claimed by the Company and indemnified by the FDIC under the agreement that are recovered by the Company through May 2020 are to be shared with the FDIC in the same proportion as they were indemnified by the FDIC. In addition, the agreement specified that at the end of the agreement in May 2020, to the extent that total claimed losses plus servicing expenses, net of recoveries, claimed under the agreement over the entire ten year period of the agreement did not meet a certain threshold, the Company would have been required to pay to the FDIC a “true up” amount equal to fifty percent of the difference of the threshold and actual claimed losses plus servicing expenses, net of recoveries. On May 9, 2017, the Company and the FDIC terminated their loss sharing agreements. As part of the termination agreement, the Company paid the FDIC $184,000, and recorded a $712,000 gain representing the difference between the Company’s payment to the FDIC and the recorded payable balance on May 9, 2017.

Other Assets

Other Assets	12 Months Ended
	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other Assets	Note 12 – Other Assets Other assets were comprised of (in thousands): As of December 31, 2017 2016 Deferred tax asset, net (Note 22) $ 21,697 $ 36,199 Prepaid expense 4,111 3,045 Software 1,126 2,039 Advanced compensation 16 249 Capital Trusts 1,706 1,702 Investment in Low Housing Tax Credit Funds 16,854 18,465 Life insurance proceeds receivable 2,242 2,120 Prepaid Taxes 4,754 6,460 Premises held for sale — 2,896 Miscellaneous other assets 2,545 1,568 Total other assets $ 55,051 $ 74,743

Deposits

Deposits	12 Months Ended
	Dec. 31, 2017
Banking and Thrift [Abstract]
Deposits	Note 13 – Deposits A summary of the balances of deposits follows (in thousands): December 31, 2017 2016 Noninterest-bearing demand $ 1,368,218 $ 1,275,745 Interest-bearing demand 971,459 887,625 Savings 1,364,518 1,397,036 Time certificates, over $250,000 73,596 75,184 Other time certificates 231,340 259,970 Total deposits $ 4,009,131 $ 3,895,560 Certificate of deposit balances of $50,000,000 from the State of California were included in time certificates over $250,000 at December 31, 2017 and 2016. The Bank participates in a deposit program offered by the State of California whereby the State may make deposits at the Bank’s request subject to collateral and credit worthiness constraints. The negotiated rates on these State deposits are generally more favorable than other wholesale funding sources available to the Bank. Overdrawn deposit balances of $1,366,000 and $1,191,000 were classified as consumer loans at December 31, 2017 and 2016, respectively. At December 31, 2017, the scheduled maturities of time deposits were as follows (in thousands): Scheduled Maturities 2018 2019 $ 250,277 2020 23,577 2021 17,699 2020 8,887 Thereafter 4,496 Total $ 304,936

Reserve for Unfunded Commitment

Reserve for Unfunded Commitments	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Reserve for Unfunded Commitments	Note 14 – Reserve for Unfunded Commitments The following tables summarize the activity in reserve for unfunded commitments for the periods indicated (dollars in thousands): Years ended December 31, 2017 2016 2015 Balance at beginning of period $ 2,719 $ 2,475 $ 2,145 Provision for losses – Unfunded commitments 445 244 330 Balance at end of period $ 3,164 $ 2,719 $ 2,475

Other Liabilities

Other Liabilities	12 Months Ended
	Dec. 31, 2017
Other Liabilities Disclosure [Abstract]
Other Liabilities	Note 15 – Other Liabilities Other liabilities were comprised of (in thousands): December 31, 2017 2016 Deferred compensation $ 6,605 $ 6,525 Pension liability 28,472 26,645 Joint beneficiary agreements 3,365 3,007 Low income housing tax credit fund commitments 8,554 15,176 Accrued salaries and benefits expense 6,619 5,704 Loan escrow and servicing payable 1,958 2,146 Deferred revenue 1,228 726 Litigation contingency 1,450 1,450 Miscellaneous other liabilities 5,007 5,985 Total other liabilities $ 63,258 $ 67,364

Other Borrowings

Other Borrowings	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Other Borrowings	Note 16 – Other Borrowings A summary of the balances of other borrowings follows: December 31, 2017 2016 (in thousands) FHLB collateralized borrowing, fixed rate, as of December 31, 2017 of 1.38%, payable on January 2, 2018 $ 104,729 — Other collateralized borrowings, fixed rate, as of December 31, 2017 of 0.05%, payable on January 2, 2018 17,437 $ 17,493 Total other borrowings $ 122,166 $ 17,493 The Company did not enter into any other borrowings or repurchase agreements during 2017 or 2016. The Company maintains a collateralized line of credit with the FHLB. Based on the FHLB stock requirements at December 31, 2017, this line provided for maximum borrowings of $1,365,325,000 of which $104,729,000 was outstanding, leaving $1,260,596,000 available. As of December 31, 2017, the Company had designated investment securities with a fair value of $67,325,000 and loans totaling $1,992,980,000 as potential collateral under this collateralized line of credit with the FHLB. The Company had $17,437,000 and $17,493,000 of other collateralized borrowings at December 31, 2017 and 2016, respectively. Other collateralized borrowings are generally overnight maturity borrowings from non-financial The Company maintains a collateralized line of credit with the Federal Reserve Bank of San Francisco (“FRB”). As of December 31, 2017, this line provided for maximum borrowings of $134,660,000 of which none was outstanding, leaving $134,660,000 available. As of December 31, 2017, the Company has designated investment securities with fair value of $17,000 and loans totaling $245,532,000 as potential collateral under this collateralized line of credit with the FRB. The Company has available unused correspondent banking lines of credit from commercial banks totaling $20,000,000 for federal funds transactions at December 31, 2017.

Junior Subordinated Debt

Junior Subordinated Debt	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Junior Subordinated Debt	Note 17 – Junior Subordinated Debt At December 31, 2017, the Company had five wholly-owned subsidiary business trusts that had issued $62.9 million of trust preferred securities (the “Capital Trusts”). Trust preferred securities accrue and pay distributions periodically at specified annual rates as provided in the indentures. The trusts used the net proceeds from the offering to purchase a like amount of subordinated debentures (the “Debentures”) of the Company. The Debentures are the sole assets of the trusts. The Company’s obligations under the subordinated debentures and related documents, taken together, constitute a full and unconditional guarantee by the Company of the obligations of the trusts. The trust preferred securities are mandatorily redeemable upon the maturity of the Debentures, or upon earlier redemption as provided in the indentures. The Company has the right to redeem the Debentures in whole (but not in part) on or after specific dates, at a redemption price specified in the indentures plus any accrued but unpaid interest to the redemption date. The Company also has a right to defer consecutive payments of interest on the debentures for up to five years. The Company organized two of the Capital Trusts. The Company acquired its three other Capital Trusts and assumed their related Debentures as a result of its acquisition of North Valley Bancorp. At the acquisition date of October 3, 2014, the Debentures associated with North Valley Bancorp’s three Capital Trusts were recorded on the Company’s books at their fair values of $5,006,000, $3,918,000, and $6,063,000, respectively. The related fair value discounts to face value of these Debentures will be amortized over the remaining time to maturity for each of these Debentures using the effective interest method. Similar, and proportional, discounts were applied to the acquired common stock interests in each of the acquired Capital Trusts and these discounts will be proportionally amortized over the remaining time to maturity for each related debenture. The recorded book values of the Debentures issued by the Capital Trusts are reflected as junior subordinated debt in the Company’s consolidated balance sheets. The common stock issued by the Capital Trusts and owned by the Company is recorded in other assets in the Company’s consolidated balance sheets. The recorded book value of the debentures issued by the Capital Trusts, less the recorded book value of the common stock of the Capital Trusts owned by the Company, continues to qualify as Tier 1 or Tier 2 capital under interim guidance issued by the Board of Governors of the Federal Reserve System. The following table summarizes the terms and recorded balance of each subordinated debenture as of the date indicated (dollars in thousands): Coupon Rate As of December 31, 2017 Subordinated Maturity Face (Variable) Current Recorded Debt Series Date Value 3 mo. LIBOR + Coupon Rate Book Value TriCo Cap Trust I 10/7/2033 $20,619 3.05% 4.41% $ 20,619 TriCo Cap Trust II 7/23/2034 20,619 2.55% 3.91% 20,619 North Valley Trust II 4/24/2033 6,186 3.25% 4.63% 5,135 North Valley Trust III 4/24/2034 5,155 2.80% 4.16% 4,041 North Valley Trust IV 3/15/2036 10,310 1.33% 2.92% 6,444 $62,889 $ 56,858

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 18 – Commitments and Contingencies Restricted Cash Balances Lease Commitments non-cancelable non-cancelable Operating Leases (in thousands) 2018 $ 3,278 2019 2,499 2020 1,847 2021 1,488 2022 757 Thereafter 798 Future minimum lease payments $ 10,667 Rent expense under operating leases was $5,885,000 in 2017, $6,082,000 in 2016, and $6,241,000 in 2015. Rent expense was offset by rent income of $44,000 in 2017, $220,000 in 2016, and $217,000 in 2015. Financial Instruments with Off-Balance-Sheet off-balance The Company’s exposure to loss in the event of nonperformance by the other party to the financial instrument for commitments to extend credit and standby letters of credit written is represented by the contractual amount of those instruments. The Company uses the same credit policies in making commitments and conditional obligations as it does for on-balance The following table presents a summary of the Bank’s commitments and contingent liabilities: (in thousands) December 31, December 31, Financial instruments whose amounts represent risk: Commitments to extend credit: Commercial loans $ 257,220 $ 220,836 Consumer loans 422,958 406,855 Real estate mortgage loans 66,267 42,184 Real estate construction loans 187,097 97,399 Standby letters of credit 13,075 12,763 Deposit account overdraft privilege 98,260 98,583 Commitments to extend credit are agreements to lend to a customer as long as there is no violation of any condition established in the contract. Commitments generally have fixed expiration dates of one year or less or other termination clauses and may require payment of a fee. Since many of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. The Company evaluates each customer’s credit worthiness on a case-by-case Standby letters of credit are conditional commitments issued by the Company to guarantee the performance of a customer to a third party. Those guarantees are primarily issued to support private borrowing arrangements. Most standby letters of credit are issued for one year or less. The credit risk involved in issuing letters of credit is essentially the same as that involved in extending loan facilities to customers. Collateral requirements vary, but in general follow the requirements for other loan facilities. Deposit account overdraft privilege amount represents the unused overdraft privilege balance available to the Company’s deposit account holders who have deposit accounts covered by an overdraft privilege. The Company has established an overdraft privilege for certain of its deposit account products whereby all holders of such accounts who bring their accounts to a positive balance at least once every thirty days receive the overdraft privilege. The overdraft privilege allows depositors to overdraft their deposit account up to a predetermined level. The predetermined overdraft limit is set by the Company based on account type. Legal Proceedings in-store non-exempt non-binding In addition to this, on January 20, 2015, a then-current Personal Banker at one of the Bank’s in-store non-exempt non-binding As part of the mediations, which took place concurrently, the Bank agreed in principal to settle the two matters in a consolidated settlement proceeding. The agreement was preliminarily approved by the court and notices were sent to the members of the purported classes. After reviewing the received claims, on January 12, 2018, the final settlement agreement was approved by the court. The total cost to the bank was $1,469,000, as compared to the balance accrued for litigation contingencies as of December 31, 2017 and 2016 of $1,450,000. Neither the Company nor its subsidiaries are a party to any other pending legal proceedings that are material, nor is their property the subject of any other material pending legal proceeding at this time. All other legal proceedings are routine and arise out of the ordinary course of the Bank’s business. None of those proceedings are currently expected to have a material adverse impact upon the Company’s and the Bank’s business, their consolidated financial position nor their operations in any material amount not already accrued, after taking into consideration any applicable insurance. Other Commitments and Contingencies The Bank owns 13,396 shares of Class B common stock of Visa Inc. which are convertible into Class A common stock at a conversion ratio of 1.648265 per Class B share. As of December 31, 2017, the value of the Class A shares was $114.02 per share. Utilizing the conversion ratio, the value of unredeemed Class A equivalent shares owned by the Bank was $2,518,000 as of December 31, 2017, and has not been reflected in the accompanying financial statements. The shares of Visa Class B common stock are restricted and may not be transferred. Visa Member Banks are required to fund an escrow account to cover settlements, resolution of pending litigation and related claims. If the funds in the escrow account are insufficient to settle all the covered litigation, Visa may sell additional Class A shares, use the proceeds to settle litigation, and further reduce the conversion ratio. If funds remain in the escrow account after all litigation is settled, the Class B conversion ratio will be increased to reflect that surplus. Mortgage loans sold to investors may be sold with servicing rights retained, with only the standard legal representations and warranties regarding recourse to the Bank. Management believes that any liabilities that may result from such recourse provisions are not significant.

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Shareholders' Equity	Note 19 – Shareholders’ Equity Dividends Paid The Bank paid to the Company cash dividends in the aggregate amounts of $19,236,000, $16,758,000, and $13,304,000 in 2017, 2016, and 2015, respectively. The Bank is regulated by the Federal Deposit Insurance Corporation (FDIC) and the State of California Department of Business Oversight. Absent approval from the Commissioner of the Department of Business Oversight, California banking laws generally limit the Bank’s ability to pay dividends to the lesser of (1) retained earnings or (2) net income for the last three fiscal years, less cash distributions paid during such period. Under this law, at December 31, 2017, the Bank could have paid dividends of $85,254,000 to the Company without the approval of the Commissioner of the Department of Business Oversight. Stock Repurchase Plan On August 21, 2007, the Board of Directors adopted a plan to repurchase, as conditions warrant, up to 500,000 shares of the Company’s common stock on the open market. The timing of purchases and the exact number of shares to be purchased will depend on market conditions. The 500,000 shares authorized for repurchase under this stock repurchase plan represented approximately 3.2% of the Company’s 15,814,662 outstanding common shares as of August 21, 2007. This stock repurchase plan has no expiration date. As of December 31, 2017, the Company had repurchased 166,600 shares under this plan. During the year ended December 31, 2017, there were no shares of common stock repurchased under this plan. Stock Repurchased Under Equity Compensation Plans During the years ended December 31, 2017, 2016, and 2015, employees tendered 107,390, 264,800, and 106,355 of the Company’s common stock with market value of $3,854,000, $7,879,000, and $2,868,000, respectively, in lieu of cash to exercise options to purchase shares of the Company’s stock and to pay income taxes related to such exercises as permitted by the Company’s shareholder-approved equity compensation plans. The tendered shares were retired. The market value of tendered shares is the last market trade price at closing on the day an option is exercised. Stock repurchased under equity incentive plans are not included in the total of stock repurchased under the stock repurchase plan announced August 21, 2007.

Stock Options and Other Equity-

Stock Options and Other Equity-Based Incentive Instruments	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Options and Other Equity-Based Incentive Instruments	Note 20 – Stock Options and Other Equity-Based Incentive Instruments In March 2009, the Company’s Board of Directors adopted the TriCo Bancshares 2009 Equity Incentive Plan (2009 Plan) covering officers, employees, directors of, and consultants to, the Company. The 2009 Plan was approved by the Company’s shareholders in May 2009. The 2009 Plan allows for the granting of the following types of “stock awards” (Awards): incentive stock options, nonstatutory stock options, performance awards, restricted stock, restricted stock unit (RSU) awards and stock appreciation rights. RSUs that vest based solely on the grantee remaining in the service of the Company for a certain amount of time, are referred to as “service condition vesting RSUs”. RSUs that vest based on the grantee remaining in the service of the Company for a certain amount of time and a market condition such as the total return of the Company’s common stock versus the total return of an index of bank stocks, are referred to as “market plus service condition vesting RSUs”. In May 2013, the Company’s shareholders approved an amendment to the 2009 Plan increasing the maximum aggregate number of shares of TriCo’s common stock which may be issued pursuant to or subject to Awards from 650,000 to 1,650,000. The number of shares available for issuance under the 2009 Plan is reduced by: (i) one share for each share of common stock issued pursuant to a stock option or a Stock Appreciation Right and (ii) two shares for each share of common stock issued pursuant to a performance award, a restricted stock award or a RSU. When Awards made under the 2009 Plan expire or are forfeited or cancelled, the underlying shares will become available for future Awards under the 2009 Plan. To the extent that a share of common stock pursuant to an Award that counted as two shares against the number of shares again becomes available for issuance under the 2009 Plan, the number of shares of common stock available for issuance under the 2009 Plan shall increase by two shares. Shares awarded and delivered under the 2009 Plan may be authorized but unissued, or reacquired shares. As of December 31, 2017, 411,900 options for the purchase of common shares, and 121,286 RSUs were outstanding, and 527,039 shares remain available for issuance, under the 2009 Plan. In May 2001, the Company adopted the TriCo Bancshares 2001 Stock Option Plan (2001 Plan) covering officers, employees, directors of, and consultants to, the Company. Under the 2001 Plan, the option exercise price cannot be less than the fair market value of the Common Stock at the date of grant except in the case of substitute options. Options for the 2001 Plan expire on the tenth anniversary of the grant date. Vesting schedules under the 2001 Plan are determined individually for each grant. As of December 31, 2017, 34,500 options for the purchase of common shares were outstanding under the 2001 Plan. As of May 2009, as a result of the shareholder approval of the 2009 Plan, no new options may be granted under the 2001 Plan. Stock option activity is summarized in the following table for the dates indicated: Number of Option Price per Share Weighted Outstanding at December 31, 2016 592,250 $ 12.63 to $ 23.21 $ 17.12 Options granted — — to — — Options exercised (145,850 ) $ 14.54 to $ 22.54 $ 17.97 Options forfeited — — to — — Outstanding at December 31, 2017 446,400 $ 12.63 to $ 23.21 $ 16.84 The following table shows the number, weighted-average exercise price, intrinsic value, and weighted average remaining contractual life of options exercisable, options not yet exercisable and total options outstanding as of December 31, 2017: Currently Currently Not Total Number of options 422,100 24,300 446,400 Weighted average exercise price $ 16.65 $ 20.21 $ 16.84 Intrinsic value (in thousands) $ 8,953 $ 429 $ 9,382 Weighted average remaining contractual term (yrs.) 3.8 5.7 3.9 The 24,300 options that are currently not exercisable as of December 31, 2017 are expected to vest, on a weighted-average basis, over the next 0.7 years, and the Company is expected to recognize $108,000 of pre-tax The following table shows the total intrinsic value of options exercised, the total fair value of options vested, total compensation costs for options recognized in income, and total tax benefit recognized in income related to compensation costs for options during the periods indicated: Years Ended December 31, 2017 2016 2015 Intrinsic value of options exercised $ 2,657,000 $ 3,483,000 $ 969,000 Fair value of options that vested $ 259,000 $ 580,000 $ 734,000 Total compensation costs for options recognized in income $ 259,000 $ 580,000 $ 734,000 Total tax benefit recognized in income related to compensation costs for options $ 109,000 $ 244,000 $ 380,000 Excess tax benefit recognized in income $ 906,000 — — During 2017, 2016 and 2015, the Company granted no options. Restricted stock unit (RSU) activity is summarized in the following table for the dates indicated: Service Condition Vesting RSUs Market Plus Service Condition Vesting RSUs Number Weighted Number Weighted Outstanding at December 31, 2016 68,450 47,426 RSUs granted 29,669 $35.36 17,939 $32.95 Additional market plus service condition RSUs vested 6,269 RSUs added through dividend credits 1,245 — RSUs released (30,896 ) (18,805 ) RSUs forfeited/expired (11 ) — Outstanding at December 31, 2017 68,457 52,829 The 68,457 of service condition vesting RSUs outstanding as of December 31, 2017 include a feature whereby each RSU outstanding is credited with a dividend amount equal to any common stock cash dividend declared and paid, and the credited amount is divided by the closing price of the Company’s stock on the dividend payable date to arrive at an additional amount of RSUs outstanding under the original grant. The 68,457 of service condition vesting RSUs outstanding as of December 31, 2017 are expected to vest, and be released, on a weighted-average basis, over the next 1.2 years. The Company expects to recognize $1,448,000 of pre-tax The 52,829 of market plus service condition vesting RSUs outstanding as of December 31, 2017 are expected to vest, and be released, on a weighted-average basis, over the next 1.4 years. The Company expects to recognize $724,000 of pre-tax The following table shows the compensation costs for RSUs recognized in income for the periods indicated: Year Ended December 31, 2017 2016 2015 Total compensation costs for RSUs recognized in income: Service condition vesting RSUs $ 895,000 $ 616,000 $ 458,000 Market plus service condition vesting RSUs $ 432,000 $ 271,000 $ 179,000

Noninterest Income and Expense

Noninterest Income and Expense	12 Months Ended
	Dec. 31, 2017
Other Income and Expenses [Abstract]
Noninterest Income and Expense	Note 21 – Noninterest Income and Expense The components of other noninterest income were as follows (in thousands): Years Ended December 31, 2017 2016 2015 Service charges on deposit accounts $ 16,056 $ 14,365 $ 14,276 ATM and interchange fees 16,727 15,859 13,364 Other service fees 3,282 3,121 2,977 Mortgage banking service fees 2,076 2,065 2,164 Change in value of mortgage servicing rights (718 ) (2,184 ) (701 ) Total service charges and fees 37,423 33,226 32,080 Gain on sale of loans 3,109 4,037 3,064 Commissions on sale of non-deposit 2,729 2,329 3,349 Increase in cash value of life insurance 2,685 2,717 2,786 Gain on sale of investments 961 — — Lease brokerage income 782 711 712 Gain on sale of foreclosed assets 711 262 991 Change in indemnification asset 490 (493 ) (207 ) Sale of customer checks 372 408 492 Life insurance benefit in excess of cash value 108 238 155 Loss on disposal of fixed assets (142 ) (147 ) (129 ) Other 793 1,275 2,054 Total other noninterest income 12,598 11,337 13,267 Total noninterest income $ 50,021 $ 44,563 $ 45,347 Mortgage loan servicing fees, net of change in fair value of mortgage loan servicing rights, totaling $1,358,000, $(119,000), and $1,463,000 were recorded in service charges and fees noninterest income for the years ended December 31, 2017, 2016, and 2015, respectively. The components of noninterest expense were as follows (in thousands): Years Ended December 31, 2017 2016 2015 Base salaries, net of deferred loan origination costs $ 54,589 $ 53,169 $ 46,822 Incentive compensation 9,227 8,872 6,964 Benefits and other compensation costs 19,114 18,683 17,619 Total salaries and benefits expense 82,930 80,724 71,405 Occupancy 10,894 10,139 10,126 Data processing and software 10,448 8,846 7,670 Equipment 7,141 6,597 5,997 ATM & POS network charges 4,752 4,999 4,190 Advertising 4,101 3,829 3,992 Professional fees 3,745 5,409 4,545 Telecommunications 2,713 2,749 3,007 Assessments 1,676 2,105 2,572 Operational losses 1,394 1,564 737 Intangible amortization 1,389 1,377 1,157 Postage 1,296 1,603 1,296 Courier service 1,035 998 1,154 Change in reserve for unfunded commitments 445 244 330 Foreclosed assets expense 231 266 490 Provision for foreclosed asset losses 162 140 502 Legal settlement — 1,450 — Merger & acquisition expense 530 784 586 Miscellaneous other 12,142 12,174 11,085 Total other noninterest expense 64,094 65,273 59,436 Total noninterest expense $ 147,024 $ 145,997 $ 130,841 Merger and acquisition expense: Base salaries, net of loan origination costs — $ 187 — Data processing and software — — $ 108 Professional fees $ 513 342 120 Other 17 255 358 Total merger expense $ 530 $ 784 $ 586

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Note 22 – Income Taxes The components of consolidated income tax expense are as follows: 2017 2016 2015 (in thousands) Current tax expense Federal $ 17,835 $ 17,401 $ 21,076 State 6,650 7,121 7,139 $ 24,485 24,522 28,215 Deferred tax expense Federal 11,418 2,735 408 State 1,055 455 273 12,473 3,190 681 Total tax expense $ 36,958 $ 27,712 $ 28,896 A deferred tax asset or liability is recognized for the tax consequences of temporary differences in the recognition of revenue and expense for financial and tax reporting purposes. The net change during the year in the deferred tax asset or liability results in a deferred tax expense or benefit. On December 22, 2017, President Donald Trump signed into law “H.R.1”, commonly known as the “Tax Cuts and Jobs Act”, which among other items reduces the Federal corporate tax rate from 35% to 21%. The Company’s deferred tax expense as of December 31, 2017 includes $7,416,000 from the re-measurement Taxes recorded directly to shareholders’ equity are not included in the preceding table. These taxes relating to changes in unfunded status of the supplemental retirement plans amounting to $400,000 in 2017, $429,000 in 2016, and $904,000 in 2015, taxes (benefits) related to unrealized gains and losses on available-for-sale The Company recognized, as components of tax expense, tax credits and other tax benefits, and amortization expense relating to our investments in Qualified Affordable Housing Projects as followers for the periods indicated: Year ended December 31, 2017 2016 2015 (in thousands) Tax credits and other tax benefits – decrease in tax expense $ (1,753 ) $ (954 ) $ (354 ) Amortization – increase in tax expense $ 1,611 $ 757 $ 277 The carrying value of Low Income Housing Tax Credit Funds was $16,854,000 and $18,465,000 as of December 31, 2017 and 2016, respectively. As of December 31, 2017, the Company has committed to make additional capital contributions to the Low Income Housing Tax Credit Funds in the amount of $8,554,000, and these contributions are expected to be made over the next several years. The provisions for income taxes applicable to income before taxes for the years ended December 31, 2017, 2016 and 2015 differ from amounts computed by applying the statutory Federal income tax rates to income before taxes. The effective tax rate and the statutory federal income tax rate are reconciled as follows: Years Ended December 31, 2017 2016 2015 Federal statutory income tax rate 35.0 % 35.0 % 35.0 % State income taxes, net of federal tax benefit 6.9 6.8 6.6 Tax Cuts and Jobs Act impact on deferred re-measurement 9.6 — — Tax-exempt (1.9 ) (1.8 ) (0.7 ) Tax-exempt (1.3 ) (1.3 ) (1.3 ) Equity compensation (1.2 ) — — Low income housing tax credit benefits (2.3 ) (1.3 ) (0.4 ) Low income housing tax credit amortization 2.1 0.8 — Non-deductible 0.1 0.1 0.1 Non-deductible 0.2 — — Other 0.5 (0.1 ) 0.4 Effective Tax Rate 47.7 % 38.2 % 39.7 % The temporary differences, tax effected, which give rise to the Company’s net deferred tax asset recorded in other assets are as follows as of December 31 for the years indicated: 2017 2016 (in thousands) Deferred tax assets: Allowance for losses and reserve for unfunded commitments $ 9,900 $ 14,809 Deferred compensation 1,953 2,743 Accrued pension liability 6,835 9,220 Accrued bonus 171 1,727 Other accrued expenses 522 781 Unfunded status of the supplemental retirement plans 1,582 1,982 State taxes 1,397 2,257 Share based compensation 1,322 2,063 Nonaccrual interest 282 408 OREO write downs 59 132 Indemnification asset — 313 Acquisition cost basis 2,187 3,996 Unrealized loss on securities 1,008 3,730 Tax credits 581 491 Net operating loss carryforwards 1,801 3,354 Other 508 981 Total deferred tax assets 30,108 48,987 Deferred tax liabilities: Securities income (958 ) (1,362 ) Depreciation (1,987 ) (3,032 ) Merger related fixed asset valuations (30 ) (54 ) Securities accretion (315 ) (478 ) Mortgage servicing rights valuation (1,943 ) (2,710 ) Core deposit intangible (916 ) (1,813 ) Junior subordinated debt (1,783 ) (2,616 ) Prepaid expenses and other (479 ) (723 ) Total deferred tax liability (8,411 ) (12,788 ) Net deferred tax asset $ 21,697 $ 36,199 As part of the merger with North Valley Bancorp in 2014, TriCo acquired federal and state net operating loss carryforwards, capital loss carryforwards, and tax credit carryforwards. These tax attribute carryforwards will be subject to provisions of the tax law that limit the use of such losses and credits generated by a company prior to the date certain ownership changes occur. The amount of the Company’s net operating loss carryforwards that would be subject to these limitations as of December 31, 2017 were $21.4 million for California. The amount of the Company’s tax credits that would be subject to these limitations as of December 31, 2017 are $69,000 and $648,000 for federal and California, respectively. Due to the limitation, a significant portion of the state tax credits will expire regardless of whether the Company generates future taxable income. As such, the Company has recorded the future benefit of these tax credits on the books at the value which is more likely than not to be realized. These tax loss and tax credit carryforwards expire at various dates beginning in 2018. The Company believes that a valuation allowance is not needed to reduce the deferred tax assets as it is more likely than not that the results of future operations will generate sufficient taxable income to realize the deferred tax assets, including the tax attribute carryforwards acquired as part of the North Valley Bancorp merger. As part of the North Valley Bancorp merger, TriCo inherited an unrecognized tax benefit for tax positions claimed on prior year tax returns filed by North Valley Bancorp. The Company had an unrecognized tax benefit of $60,000 as of December 31, 2017, the recognition of which would reduce the Company’s tax expense by $34,000. Management does not expect the unrecognized tax benefit will materially change in the next 12 months. A summary of changes in the Company’s unrecognized tax benefit (including interest and penalties) in 2017 is as follows: (in thousands) UTB Interest/Penalties Total As of December 31, 2016 $ 114 $ 7 $ 121 Lapse of the applicable statute of limitations (54 ) (5 ) (59 ) As of December 31, 2017 $ 60 $ 2 $ 62 During the years ended December 31, 2017 and December 31, 2016 the Company recognized no interest and penalties related to taxes. The Company files income tax returns in the U.S. federal jurisdiction, and California. With few exceptions, the Company is no longer subject to U.S. federal and state/local income tax examinations by tax authorities for years before 2014 and 2013, respectively.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings Per Share	Note 23 – Earnings per Share Basic earnings per share represents income available to common shareholders divided by the weighted-average number of common shares outstanding during the period. Diluted earnings per share reflects additional common shares that would have been outstanding if dilutive potential common shares had been issued, as well as any adjustments to income that would result from assumed issuance. Potential common shares that may be issued by the Company relate solely from outstanding stock options, and are determined using the treasury stock method. Earnings per share have been computed based on the following: Years ended December 31, 2017 2016 2015 Net income (in thousands) $ 40,554 $ 44,811 $ 43,818 (number of shares in thousands) Average number of common shares outstanding 22,912 22,814 22,750 Effect of dilutive stock options 338 273 248 Average number of common shares outstanding used to calculate diluted earnings per share 23,250 23,087 22,998 Based on an average of quarterly computations, there were 0, 13,825, and 20,625 options and restricted stock units excluded from the computation of annual diluted earnings per share for the years ended December 31, 2017, 2016 and 2015, respectively, because the effect of these options and restricted stock units were antidilutive.

Comprehensive Income

Comprehensive Income	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Comprehensive Income	Note 24 – Comprehensive Income Accounting principles generally require that recognized revenue, expenses, gains and losses be included in net income. Although certain changes in assets and liabilities, such as unrealized gains and losses on available-for-sale Years Ended December 31, 2017 2016 2015 (in thousands) Unrealized holding losses on available for sale securities before reclassifications $ 6,422 $ (11,015 ) $ (1,895 ) Amounts reclassified out of accumulated other comprehensive income (961 ) — — Unrealized holding losses on available for sale securities after reclassifications 5,461 (11,015 ) (1,895 ) Tax effect (2,296 ) 4,631 797 Unrealized holding losses on available for sale securities, net of tax 3,165 (6,384 ) (1,098 ) Change in unfunded status of the supplemental retirement plans before reclassifications (1,016 ) 511 1,384 Amounts reclassified out of accumulated other comprehensive income: Amortization of prior service cost (12 ) (40 ) (57 ) Amortization of actuarial losses 390 550 823 Total amounts reclassified out of accumulated other comprehensive income 378 510 766 Change in unfunded status of the supplemental retirement plans after reclassifications (638 ) 1,021 2,150 Tax effect 268 (429 ) (904 ) Change in unfunded status of the supplemental retirement plans, net of tax (370 ) 592 1,246 Change in joint beneficiary agreement liability before reclassifications (110 ) (343 ) 277 Amounts reclassified out of accumulated other comprehensive income — — — Change in joint beneficiary agreement liability after reclassifications (110 ) (343 ) 277 Tax effect — — — Change in joint beneficiary agreement liability, net of tax (110 ) (343 ) 277 Total other comprehensive income (loss) $ 2,685 $ (6,135 ) $ 425 The components of accumulated other comprehensive income, included in shareholders’ equity, are as follows: December 31, 2017 2016 (in thousands) Net unrealized gains on available for sale securities $ (3,409 ) $ (8,870 ) Tax effect 1,008 3,729 Unrealized holding gains on available for sale securities, net of tax (2,401 ) (5,141 ) Unfunded status of the supplemental retirement plans (5,352 ) (4,714 ) Tax effect 2,250 1,982 Unfunded status of the supplemental retirement plans, net of tax (3,102 ) (2,732 ) Joint beneficiary agreement liability (150 ) (40 ) Tax effect — — Joint beneficiary agreement liability, net of tax (150 ) (40 ) Accumulated other comprehensive loss $ (5,228 ) $ (7,913 )

Retirement Plans

Retirement Plans	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Retirement Plans	Note 25 – Retirement Plans 401(k) Plan The Company sponsors a 401(k) Plan whereby substantially all employees age 21 and over with 90 days of service may participate. Participants may contribute a portion of their compensation subject to certain limits based on federal tax laws. Prior to July 1, 2015, the Company did not contribute to the 401(k) Plan. Effective July 1, 2015, the Company initiated a discretionary matching contribution equal to 50% of participant’s elective deferrals each quarter, up to 4% of eligible compensation. The Company recorded $776,000, $678,000, and $300,000, of salaries & benefits expense attributable to the 401(k) Plan matching contribution during the years 2017, 2016, and 2015, respectively. The Company made $767,000, $811,000, and $0, of 401(k) Plan matching contributions during the years 2017, 2016, and 2015, respectively. Employee Stock Ownership Plan Substantially all employees with at least one year of service are covered by a discretionary employee stock ownership plan (ESOP). Contributions are made to the plan at the discretion of the Board of Directors. Contributions to the plan totaling $2,073,000, $1,368,000, and $2,651,000 were made during 2017, 2016, and 2015, respectively. Expenses related to the Company’s ESOP, are included in benefits and other compensation costs under salaries and benefits expense, and were $2,149,000, $1,831,000, and $2,282,000 during 2017, 2016, and 2015, respectively. Company shares owned by the ESOP are paid dividends and included in the calculation of earnings per share exactly as other common shares outstanding. Deferred Compensation Plans The Company has deferred compensation plans for certain directors and key executives, which allow certain directors and key executives designated by the Board of Directors of the Company to defer a portion of their compensation. The Company has purchased insurance on the lives of the participants and intends to hold these policies until death as a cost recovery of the Company’s deferred compensation obligations of $6,605,000, and $6,525,000 at December 31, 2017 and 2016, respectively. Earnings credits on deferred balances totaling $478,000 in 2017, $487,000 in 2016, and $538,000 in 2015 are included in noninterest expense. Supplemental Retirement Plans The Company has supplemental retirement plans for certain directors and key executives. These plans are non-qualified The Company recorded in other liabilities the unfunded status of the supplemental retirement plans of $5,352,000 and $4,714,000 related to the supplemental retirement plans as of December 31, 2017 and 2016, respectively. These amounts represent the amount by which the projected benefit obligations for these retirement plans exceeded the fair value of plan assets plus amounts previously accrued related to the plans. The projected benefit obligation is recorded in other liabilities. At December 31, 2017 and 2016, the unfunded status of the supplemental retirement plans of $5,352,000 and $4,714,000 were offset by a reduction of shareholders’ equity accumulated other comprehensive loss of $3,102,000 and $2,732,000, respectively, representing the after-tax year-end December 31, (in thousands) 2017 2016 Transition obligation $ 4 $ 7 Prior service cost (248 ) (75 ) Net actuarial loss 5,596 4,782 Amount included in accumulated other comprehensive loss 5,352 4,714 Deferred tax benefit (2,250 ) (1,982 ) Amount included in accumulated other comprehensive loss, net of tax $ 3,102 $ 2,732 Information pertaining to the activity in the supplemental retirement plans, using a measurement date of December 31, is as follows: December 31, 2017 2016 (in thousands) Change in benefit obligation: Benefit obligation at beginning of year $ (26,645 ) $ (26,184 ) Acquisition — — Service cost (941 ) (1,042 ) Interest cost (991 ) (1,025 ) Actuarial (loss)/gain (1,203 ) 511 Plan amendments 185 — Benefits paid 1,123 1,095 Benefit obligation at end of year $ (28,472 ) $ (26,645 ) Change in plan assets: Fair value of plan assets at beginning of year $ — $ — Fair value of plan assets at end of year $ — $ — Funded status $ (28,472 ) $ (26,645 ) Unrecognized net obligation existing at January 1, 1986 4 7 Unrecognized net actuarial loss 5,596 4,782 Unrecognized prior service cost (248 ) (75 ) Accumulated other comprehensive income (5,352 ) (4,714 ) Accrued benefit cost $ (28,472 ) $ (26,645 ) Accumulated benefit obligation $ (26,432 ) $ (25,241 ) The following table sets forth the net periodic benefit cost recognized for the supplemental retirement plans: Years Ended December 31, 2017 2016 2015 (in thousands) Net pension cost included the following components: Service cost-benefits earned during the period $ 941 $ 1,042 $ 1,023 Interest cost on projected benefit obligation 991 1,025 957 Amortization of net obligation at transition 2 2 2 Amortization of prior service cost (12 ) (41 ) (57 ) Recognized net actuarial loss 390 549 823 Net periodic pension cost $ 2,312 $ 2,577 $ 2,748 The following table sets forth assumptions used in accounting for the plans: Years Ended December 31, 2017 2016 2015 Discount rate used to calculate benefit obligation 3.40 % 3.80 % 4.00 % Discount rate used to calculate net periodic pension cost 3.84 % 4.00 % 3.65 % Average annual increase in executive compensation 3.25 % 2.50 % 2.50 % Average annual increase in director compensation 0.00 % 2.50 % 2.50 % The following table sets forth the expected benefit payments to participants and estimated contributions to be made by the Company under the supplemental retirement plans for the years indicated: Years Ended Expected Benefit Estimated (in thousands) 2018 $ 1,106 $ 1,106 2019 1,067 1,067 2020 1,233 1,233 2021 1,859 1,859 2022 2,008 2,008 2023-2027 $ 10,169 $ 10,169

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Related Party Transactions	Note 26 – Related Party Transactions Certain directors, officers, and companies with which they are associated were customers of, and had banking transactions with, the Company or the Bank in the ordinary course of business. The following table summarizes the activity in these loans for the periods indicated (in thousands): Balance December 31, 2015 $ 4,201 Advances/new loans 730 Removed/payments (2,499 ) Balance December 31, 2016 $ 2,432 Advances/new loans 437 Removed/payments (721 ) Balance December 31, 2017 $ 2,148 Deposits of directors, officers and other related parties to the Bank totaled $46,025,000 and $69,755,000 at December 31, 2017 and 2016, respectively.

Fair Value Measurement

Fair Value Measurement	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurement	Note 27 – Fair Value Measurement The Company utilizes fair value measurements to record fair value adjustments to certain assets and liabilities and to determine fair value disclosures. In estimating fair value, the Company utilizes valuation techniques that are consistent with the market approach, income approach, and/or the cost approach. Inputs to valuation techniques include the assumptions that market participants would use in pricing an asset or liability including assumptions about the risk inherent in a particular valuation technique, the effect of a restriction on the sale or use of an asset and the risk of nonperformance. Securities available-for-sale The Company groups assets and liabilities at fair value in three levels, based on the markets in which the assets and liabilities are traded and the observable nature of the assumptions used to determine fair value. These levels are: Level 1 - Valuation is based upon quoted prices for identical instruments traded in active markets. Level 2 - Valuation is based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant assumptions are observable in the market. Level 3 - Valuation is generated from model-based techniques that use at least one significant assumption not observable in the market. These unobservable assumptions reflect estimates of assumptions that market participants would use in pricing the asset or liability. Valuation techniques include use of option pricing models, discounted cash flow models and similar techniques. Securities available for sale over-the-counter Loans held for sale Impaired originated and PNCI loans Foreclosed assets Mortgage servicing rights The table below presents the recorded amount of assets and liabilities measured at fair value on a recurring basis (in thousands): Total Level 1 Level 2 Level 3 Fair value at December 31, 2017 Securities available-for-sale: Obligations of U.S. government corporations and agencies $ 604,789 — $ 604,789 — Obligations of states and political subdivisions 123,156 — 123,156 — Marketable equity securities 2,938 $ 2,938 — — Mortgage servicing rights 6,687 — — $ 6,687 Total assets measured at fair value $ 737,570 $ 2,938 $ 727,945 $ 6,687 Total Level 1 Level 2 Level 3 Fair value at December 31, 2016 Securities available-for-sale: Obligations of U.S. government corporations and agencies $ 429,678 — $ 429,678 — Obligations of states and political subdivisions 117,617 — 117,617 — Marketable equity securities 2,938 $ 2,938 — — Mortgage servicing rights 6,595 — — $ 6,595 Total assets measured at fair value $ 556,828 $ 2,938 $ 547,295 $ 6,595 Transfers between levels of the fair value hierarchy are recognized on the actual date of the event or circumstances that caused the transfer, which generally corresponds with the Company’s quarterly valuation process. There were no transfers between any levels during 2017 or 2016. The following table provides a reconciliation of assets and liabilities measured at fair value using significant unobservable inputs (Level 3) on a recurring basis during the years ended December 31, 2017, 2016, and 2015. Had there been any transfer into or out of Level 3 during 2017, 2016, or 2015, the amount included in the “Transfers into (out of) Level 3” column would represent the beginning balance of an item in the period (interim quarter) during which it was transferred (in thousands): Ending Transfers Change Issuances Beginning Year ended December 31, 2017: Mortgage servicing rights $ 6,687 — $ (718 ) $ 810 $ 6,595 2016: Mortgage servicing rights $ 6,595 — $ (2,184 ) $ 1,161 $ 7,618 2015: Mortgage servicing rights $ 7,618 — $ (701 ) $ 941 $ 7,378 The Company’s method for determining the fair value of mortgage servicing rights is described in Note 1. The key unobservable inputs used in determining the fair value of mortgage servicing rights are mortgage prepayment speeds and the discount rate used to discount cash projected cash flows. Generally, any significant increases in the mortgage prepayment speed and discount rate utilized in the fair value measurement of the mortgage servicing rights will result in a negative fair value adjustments (and decrease in the fair value measurement). Conversely, a decrease in the mortgage prepayment speed and discount rate will result in a positive fair value adjustment (and increase in the fair value measurement). Note 10 contains additional information regarding mortgage servicing rights. The following table presents quantitative information about recurring Level 3 fair value measurements at December 31, 2017 and 2016: Fair Value Valuation Unobservable Range, December 31, 2017 Mortgage Servicing Rights $ 6,687 Discounted cash flow Constant prepayment rate 6.2%-22.0%, 8.9% Discount rate 13.0%-15.0%, 13.0% December 31, 2016 Mortgage Servicing Rights $ 6,595 Discounted cash flow Constant prepayment rate 6.9%-16.6%, 8.8% Discount rate 14.0%-16.0%, 14.0% The tables below present the recorded amount of assets and liabilities measured at fair value on a nonrecurring basis, as of the dates indicated, that had a write-down or an additional allowance provided during the periods indicated (in thousands): Total Level 1 Level 2 Level 3 Total Gains Year ended December 31, 2017 Fair value: Impaired Originated & PNCI loans $ 2,767 — — $ 2,767 $ (1,452 ) Foreclosed assets 2,217 2,217 (135 ) Total assets measured at fair value $ 4,984 — — $ 4,984 $ (1,587 ) Total Level 1 Level 2 Level 3 Total Gains Year ended December 31, 2016 Fair value: Impaired Originated & PNCI loans $ 1,107 — — $ 1,107 $ (409 ) Foreclosed assets 2,253 2,253 (86 ) Total assets measured at fair value $ 3,360 — — $ 3,360 $ (495 ) The impaired Originated and PNCI loan amount above represents impaired, collateral dependent loans that have been adjusted to fair value. When we identify a collateral dependent loan as impaired, we measure the impairment using the current fair value of the collateral, less selling costs. Depending on the characteristics of a loan, the fair value of collateral is generally estimated by obtaining external appraisals. If we determine that the value of the impaired loan is less than the recorded investment in the loan, we recognize this impairment and adjust the carrying value of the loan to fair value through the allowance for loan and lease losses. The loss represents charge-offs or impairments on collateral dependent loans for fair value adjustments based on the fair value of collateral. The carrying value of loans fully charged-off The foreclosed assets amount above represents impaired real estate that has been adjusted to fair value. Foreclosed assets represent real estate which the Bank has taken control of in partial or full satisfaction of loans. At the time of foreclosure, other real estate owned is recorded at fair value less costs to sell, which becomes the property’s new basis. Any write-downs based on the asset’s fair value at the date of acquisition are charged to the allowance for loan and lease losses. After foreclosure, management periodically performs valuations such that the real estate is carried at the lower of its new cost basis or fair value, net of estimated costs to sell. Fair value adjustments on other real estate owned are recognized within net loss on real estate owned. The loss represents impairments on non-covered The Company’s property appraisals are primarily based on the sales comparison approach and income approach methodologies, which consider recent sales of comparable properties, including their income generating characteristics, and then make adjustments to reflect the general assumptions that a market participant would make when analyzing the property for purchase. These adjustments may increase or decrease an appraised value and can vary significantly depending on the location, physical characteristics and income producing potential of each property. Additionally, the quality and volume of market information available at the time of the appraisal can vary from period to period and cause significant changes to the nature and magnitude of comparable sale adjustments. Given these variations, comparable sale adjustments are generally not a reliable indicator for how fair value will increase or decrease from period to period. Under certain circumstances, management discounts are applied based on specific characteristics of an individual property. The following table presents quantitative information about Level 3 fair value measurements for financial instruments measured at fair value on a nonrecurring basis at December 31, 2017 and 2016: December 31, 2017 Fair Value Valuation Technique Unobservable Inputs Range, Impaired Originated & PNCI loans $ 2,767 Sales comparison approach Income approach Adjustment for differences between comparable sales Capitalization rate Not meaningful N/A Foreclosed assets (Land & construction) $ 1,341 Sales comparison approach Adjustment for differences between comparable sales Not meaningful Foreclosed assets (residential (Residential real estate) $ 622 Sales comparison approach Adjustment for differences between comparable sales Not meaningful Foreclosed assets (Commercial real estate) $ 254 Sales comparison approach Adjustment for differences between comparable sales Not meaningful December 31, 2016 Fair Value Valuation Technique Unobservable Inputs Range, Impaired Originated & PNCI loans $ 1,107 Sales comparison approach Income approach Adjustment for differences between comparable sales Capitalization rate Not meaningful N/A Foreclosed assets (Land & construction) $ 15 Sales comparison approach Adjustment for differences between comparable sales Not meaningful Foreclosed assets (residential (Residential real estate) $ 1,564 Sales comparison approach Adjustment for differences between comparable sales Not meaningful Foreclosed assets (Commercial real estate) $ 674 Sales comparison approach Adjustment for differences between comparable sales Not meaningful In addition to the methods and assumptions used to estimate the fair value of each class of financial instrument noted above, the following methods and assumptions were used to estimate the fair value of other classes of financial instruments for which it is practical to estimate the fair value. Short-term Instruments Securities held to maturity over-the-counter Restricted Equity Securities Originated and PNCI loans PCI Loans Deposit Liabilities Other Borrowings Junior Subordinated Debentures Accrued Interest Receivable and Payable Commitments to Extend Credit and Standby Letters of Credit Fair values for financial instruments are management’s estimates of the values at which the instruments could be exchanged in a transaction between willing parties. These estimates are subjective and may vary significantly from amounts that would be realized in actual transactions. In addition, other significant assets are not considered financial assets including, any mortgage banking operations, deferred tax assets, and premises and equipment. Further, the tax ramifications related to the realization of the unrealized gains and losses can have a significant effect on the fair value estimates and have not been considered in any of these estimates. The estimated fair values of financial instruments that are reported at amortized cost in the Corporation’s consolidated balance sheets, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value, were as follows (in thousands): December 31, 2017 December 31, 2016 Carrying Fair Carrying Fair Financial assets: Level 1 inputs: Cash and due from banks $ 105,968 $ 105,968 $ 92,197 $ 92,197 Cash at Federal Reserve and other banks 99,460 99,460 213,415 213,415 Level 2 inputs: Securities held to maturity 514,844 518,165 602,536 603,203 Restricted equity securities 16,956 N/A 16,596 N/A Loans held for sale 4,616 4,616 2,998 2,998 Level 3 inputs: Loans, net 2,984,842 2,992,225 2,727,090 2,763,473 Financial liabilities: Level 2 inputs: Deposits 4,009,131 4,006,620 3,895,560 3,893,941 Other borrowings 122,166 122,166 17,493 17,493 Level 3 inputs: Junior subordinated debt $ 56,858 $ 58,466 $ 56,667 $ 49,033 Contract Fair Contract Fair Off-balance Level 3 inputs: Commitments $ 933,542 $ 9,335 $ 767,274 $ 7,673 Standby letters of credit $ 13,075 $ 131 $ 12,763 $ 128 Overdraft privilege commitments $ 98,260 $ 983 $ 98,583 $ 986

TriCo Bancshares Condensed Fina

TriCo Bancshares Condensed Financial Statements (Parent Only)	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
TriCo Bancshares Condensed Financial Statements (Parent Only)	Note 28 – TriCo Bancshares Condensed Financial Statements (Parent Only) Condensed Balance Sheets December 31, 2017 2016 (in thousands) Assets Cash and Cash equivalents $ 3,924 $ 2,802 Investment in Tri Counties Bank 557,538 529,907 Other assets 1,721 1,711 Total assets $ 563,183 $ 534,420 Liabilities and shareholders’ equity Other liabilities $ 517 $ 406 Junior subordinated debt 56,858 56,667 Total liabilities 57,375 57,073 Shareholders’ equity: Common stock, no par value: authorized 50,000,000 shares; issued and outstanding 22,955,963 and 22,867,802 shares, respectively 255,836 252,820 Retained earnings 255,200 232,440 Accumulated other comprehensive loss, net (5,228 ) (7,913 ) Total shareholders’ equity 505,808 477,347 Total liabilities and shareholders’ equity $ 563,183 $ 534,420 Condensed Statements of Income Years ended December 31, 2017 2016 2015 (in thousands) Interest expense $ (2,535 ) $ (2,229 ) $ (1,977 ) Administration expense (915 ) (725 ) (814 ) Loss before equity in net income of Tri Counties Bank (3,450 ) (2,954 ) (2,791 ) Equity in net income of Tri Counties Bank: Distributed 19,236 16,758 13,304 Undistributed 23,359 29,764 32,131 Income tax benefit 1,409 1,243 1,174 Net income $ 40,554 $ 44,811 $ 43,818 Condensed Statements of Comprehensive Income Years ended December 31, 2017 2016 2015 (in thousands) Net income $ 40,554 $ 44,811 $ 43,818 Other comprehensive income (loss), net of tax: Unrealized holding gains (losses) on securities arising during the period 3,165 (6,384 ) (1,098 ) Change in minimum pension liability (370 ) 592 1,246 Change in joint beneficiary agreement liability (110 ) (343 ) 277 Other comprehensive income (loss) 2,685 (6,135 ) 425 Comprehensive income $ 43,239 $ 38,676 $ 44,243 Condensed Statements of Cash Flows Years ended December 31, 2017 2016 2015 (in thousands) Operating activities: Net income $ 40,554 $ 44,811 $ 43,818 Adjustments to reconcile net income to net cash provided by operating activities: Undistributed equity in earnings of Tri Counties Bank (23,359 ) (29,764 ) (32,131 ) Equity compensation vesting expense 1,586 1,467 1,370 Equity compensation tax effect — (155 ) 68 Net change in other assets and liabilities (1,295 ) (1,210 ) (1,120 ) Net cash provided by operating activities 17,486 15,149 12,005 Investing activities: None Financing activities: Issuance of common stock through option exercise 396 518 660 Equity compensation tax effect — 155 (68 ) Repurchase of common stock (1,629 ) (1,890 ) (412 ) Cash dividends paid — common (15,131 ) (13,695 ) (11,849 ) Net cash used for financing activities (16,364 ) (14,912 ) (11,669 ) Increase in cash and cash equivalents 1,122 237 336 Cash and cash equivalents at beginning of year 2,802 2,565 2,229 Cash and cash equivalents at end of year $ 3,924 $ 2,802 $ 2,565

Regulatory Matters

Regulatory Matters	12 Months Ended
	Dec. 31, 2017
Banking and Thrift [Abstract]
Regulatory Matters	Note 29 – Regulatory Matters The Company is subject to various regulatory capital requirements administered by federal banking agencies. Failure to meet minimum capital requirements can initiate certain mandatory, and possibly additional discretionary actions by regulators that, if undertaken, could have a direct material effect on the Company’s consolidated financial statements. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, the Company must meet specific capital guidelines that involve quantitative measures of the Company’s assets, liabilities and certain off-balance-sheet The following tables present actual and required capital ratios as of December 31, 2017 and 2016 for the Company and the Bank under Basel III Capital Rules. The minimum capital amounts presented include the minimum required capital levels as of December 31, 2017 and 2016 based on the phased-in phased-in. Actual Minimum Capital Phase-in Minimum Capital Required to be Amount Ratio Amount Ratio Amount Ratio Amount Ratio (dollars in thousands) As of December 31, 2017: Total Capital (to Risk Weighted Assets): Consolidated $ 528,805 14.07 % $ 347,694 9.250 % $ 394,679 10.50 % N/A N/A Tri Counties Bank $ 525,384 13.98 % $ 347,535 9.250 % $ 394,499 10.50 % $ 375,713 10.00 % Tier 1 Capital (to Risk Weighted Assets): Consolidated $ 495,318 13.18 % $ 272,517 7.250 % $ 319,502 8.50 % N/A N/A Tri Counties Bank $ 491,897 13.09 % $ 272,392 7.250 % $ 319,356 8.50 % $ 300,570 8.00 % Common equity Tier 1 Capital (to Risk Weighted Assets): Consolidated $ 440,643 11.72 % $ 216,134 5.750 % $ 263,120 7.00 % N/A N/A Tri Counties Bank $ 491,897 13.09 % $ 216,035 5.750 % $ 262,999 7.00 % $ 244,214 6.50 % Tier 1 Capital (to Average Assets): Consolidated $ 495,318 10.80 % $ 183,400 4.000 % $ 183,400 4.00 % N/A N/A Tri Counties Bank $ 491,897 10.73 % $ 183,394 4.000 % $ 183,394 4.00 % $ 229,243 5.00 % As of December 31, 2016: Total Capital (to Risk Weighted Assets): Consolidated $ 503,283 14.77 % $ 293,854 8.625 % $ 357,735 10.50 % N/A N/A Tri Counties Bank $ 500,876 14.71 % $ 293,706 8.625 % $ 357,556 10.50 % $ 340,529 10.00 % Tier 1 Capital (to Risk Weighted Assets): Consolidated $ 468,061 13.74 % $ 225,714 6.625 % $ 289,595 8.50 % N/A N/A Tri Counties Bank $ 465,654 13.67 % $ 225,601 6.625 % $ 289,450 8.50 % $ 274,725 8.00 % Common equity Tier 1 Capital (to Risk Weighted Assets): Consolidated $ 414,632 12.17 % $ 174,609 5.125 % $ 238,490 7.00 % N/A N/A Tri Counties Bank $ 465,654 13.66 % $ 174,521 5.125 % $ 238,370 7.00 % $ 221,344 6.50 % Tier 1 Capital (to Average Assets): Consolidated $ 468,061 10.62 % $ 176,346 4.000 % $ 176,346 4.00 % N/A N/A Tri Counties Bank $ 465,654 10.56 % $ 176,341 4.000 % $ 176,341 4.00 % $ 220,426 5.00 % As of December 31, 2017, capital levels at the Company and the Bank exceed all capital adequacy requirements under the Basel III Capital Rules on a fully phased-in Beginning January 1, 2016, the Basel III Capital Rules implemented a requirement for all banking organizations to maintain a capital conservation buffer above the minimum risk-based capital requirements in order to avoid certain limitations on capital distributions, stock repurchases and discretionary bonus payments to executive officers. The capital conservation buffer is exclusively composed of common equity tier 1 capital, and it applies to each of the risk-based capital ratios but not the leverage ratio. At December 31, 2017 and 2016, the Company and the Bank were in compliance with the capital conservation buffer requirements, which were 1.25% and 0.625%, respectively. The three risk-based capital ratios will increase by 0.625% each year through 2019, at which point, the common equity tier 1 risk-based, tier 1 risk-based and total risk-based capital ratio minimums will be 7.0%, 8.5% and 10.5%, respectively.

Summary of Quarterly Results of

Summary of Quarterly Results of Operations (unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Summary of Quarterly Results of Operations (unaudited)	Note 30 – Summary of Quarterly Results of Operations (unaudited) The following table sets forth the results of operations for the four quarters of 2017 and 2016, and is unaudited; however, in the opinion of Management, it reflects all adjustments (which include only normal recurring adjustments) necessary to present fairly the summarized results for such periods. 2017 Quarters Ended December 31, September 30, June 30, March 31, (dollars in thousands, except per share data) Interest and dividend income: Loans: Discount accretion PCI – cash basis $ 516 $ 398 $ 386 $ 112 Discount accretion PCI – other 445 407 797 631 Discount accretion PNCI 528 559 987 798 All other loan interest income 36,705 35,904 34,248 33,373 Total loan interest income 38,194 37,268 36,418 34,914 Debt securities, dividends and interest bearing cash at Banks (not FTE) 8,767 8,645 8,626 8,570 Total interest income 46,961 45,913 45,044 43,484 Interest expense 1,868 1,829 1,610 1,491 Net interest income 45,093 44,084 43,434 41,993 Provision for (benefit from reversal of provision for) loan losses 1,677 765 (796 ) (1,557 ) Net interest income after provision for loan losses 43,416 43,319 44,230 43,550 Noninterest income 12,478 12,930 12,910 11,703 Noninterest expense 38,076 37,222 35,904 35,822 Income before income taxes 17,818 19,027 21,236 19,431 Income tax expense 14,829 7,130 7,647 7,352 Net income $ 2,989 $ 11,897 $ 13,589 $ 12,079 Per common share: Net income (diluted) $ 0.13 $ 0.51 $ 0.58 $ 0.52 Dividends $ 0.17 $ 0.17 $ 0.17 $ 0.15 2016 Quarters Ended December 31, September 30, June 30, March 31, (dollars in thousands, except per share data) Interest and dividend income: Loans: Discount accretion PCI – cash basis $ 483 $ 777 $ 426 $ 269 Discount accretion PCI – other 658 569 415 (45 ) Discount accretion PNCI 637 883 1,459 868 All other loan interest income 34,463 33,540 32,038 33,646 Total loan interest income 36,241 35,769 34,338 34,738 Debt securities, dividends and interest bearing cash at Banks (not FTE) 8,374 7,940 8,252 8,056 Total interest income 44,615 43,709 42,590 42,794 Interest expense 1,460 1,439 1,430 1,392 Net interest income 43,155 42,270 41,160 41,402 (Benefit from reversal of) provision for loan losses (1,433 ) (3,973 ) (773 ) 209 Net interest income after provision for loan losses 44,588 46,243 41,933 41,193 Noninterest income 12,462 11,066 11,245 9,790 Noninterest expense 36,563 37,416 38,267 33,751 Income before income taxes 20,487 19,893 14,911 17,232 Income tax expense 7,954 7,694 5,506 6,558 Net income $ 12,533 $ 12,199 $ 9,405 $ 10,674 Per common share: Net income (diluted) $ 0.54 $ 0.53 $ 0.41 $ 0.46 Dividends $ 0.15 $ 0.15 $ 0.15 $ 0.15

Summary of Significant Accoun39

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Description of Business and Basis of Presentation	Description of Business and Basis of Presentation TriCo Bancshares (the “Company” or “we”) is a California corporation organized to act as a bank holding company for Tri Counties Bank (the “Bank”). The Company and the Bank are headquartered in Chico, California. The Bank is a California-chartered bank that is engaged in the general commercial banking business in 26 California counties. The Bank operates from 57 traditional branches, 9 in-store The consolidated financial statements are prepared in accordance with accounting policies generally accepted in the United States of America and general practices in the banking industry. The financial statements include the accounts of the Company. All inter-company accounts and transactions have been eliminated in consolidation. For financial reporting purposes, the Company’s investments in the Capital Trusts of $1,721,000 are accounted for under the equity method and, accordingly, are not consolidated and are included in other assets on the consolidated balance sheet. The subordinated debentures issued and guaranteed by the Company and held by the Capital Trusts are reflected as debt on the Company’s consolidated balance sheet.
Use of Estimates in the Preparation of Financial Statements	Use of Estimates in the Preparation of Financial Statements The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires Management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions or conditions.
Significant Group Concentration of Credit Risk	Significant Group Concentration of Credit Risk The Company grants agribusiness, commercial, consumer, and residential loans to customers located throughout the northern San Joaquin Valley, the Sacramento Valley and northern mountain regions of California. The Company has a diversified loan portfolio within the business segments located in this geographical area. Management has determined that because all of the banking products and services offered by the Company are available in each branch of the Bank, all branches are located within the same economic environment and management does not allocate resources based on the performance of different lending or transaction activities, it is appropriate to aggregate the Bank branches and report them as a single operating segment.
Cash and Cash Equivalents	Cash and Cash Equivalents For purposes of the consolidated statements of cash flows, cash and cash equivalents include cash on hand, amounts due from banks, and federal funds sold. Net cash flows are reported for loan and deposit transactions and other borrowings.
Investment Securities	Investment Securities The Company classifies its debt and marketable equity securities into one of three categories: trading, available for sale or held to maturity. Trading securities are bought and held principally for the purpose of selling in the near term. Held to maturity securities are those securities which the Company has the ability and intent to hold until maturity. These securities are carried at cost adjusted for amortization of premium and accretion of discount, computed by the effective interest method over their contractual lives. All other securities not included in trading or held to maturity are classified as available for sale. Available for sale securities are recorded at fair value. Unrealized gains and losses, net of the related tax effect, on available for sale securities are reported as a separate component of other accumulated comprehensive income in shareholders’ equity until realized. Premiums and discounts are amortized or accreted over the life of the related investment security as an adjustment to yield using the effective interest method. Dividend and interest income are recognized when earned. Realized gains and losses are derived from the amortized cost of the security sold using the specific identification method. During the year ended December 31, 2017, the Company sold $24,796,000 of available for sale classified investment securities for $25,757,000 realizing a gain of $961,000. During the year ended December 31, 2016, the Company did not sell any investment securities. At December 31, 2017 and 2016, the Company did not have any securities classified as trading. The Company assesses other-than-temporary impairment (“OTTI”) based on whether it intends to sell a security or if it is likely that the Company would be required to sell the security before recovery of the amortized cost basis of the investment, which may be maturity. For debt securities, if we intend to sell the security or it is more likely than not that we will be required to sell the security before recovering its cost basis, the entire impairment loss would be recognized in earnings as an OTTI. If we do not intend to sell the security and it is not likely that we will be required to sell the security but we do not expect to recover the entire amortized cost basis of the security, only the portion of the impairment loss representing credit losses would be recognized in earnings. The credit loss on a security is measured as the difference between the amortized cost basis and the present value of the cash flows expected to be collected. Projected cash flows are discounted by the original or current effective interest rate depending on the nature of the security being measured for potential OTTI. The remaining impairment related to all other factors, the difference between the present value of the cash flows expected to be collected and fair value, is recognized as a charge to other comprehensive income (“OCI”). Impairment losses related to all other factors are presented as separate categories within OCI. The accretion of the amount recorded in OCI increases the carrying value of the investment and does not affect earnings. If there is an indication of additional credit losses the security is re-evaluated
Restricted Equity Securities	Restricted Equity Securities Restricted equity securities represent the Company’s investment in the stock of the Federal Home Loan Bank of San Francisco (“FHLB”) and are carried at par value, which reasonably approximates its fair value. While technically these are considered equity securities, there is no market for the FHLB stock. Therefore, the shares are considered as restricted investment securities. Management periodically evaluates FHLB stock for other-than-temporary impairment. Management’s determination of whether these investments are impaired is based on its assessment of the ultimate recoverability of cost rather than by recognizing temporary declines in value. The determination of whether a decline affects the ultimate recoverability of cost is influenced by criteria such as (1) the significance of any decline in net assets of the FHLB as compared to the capital stock amount for the FHLB and the length of time this situation has persisted, (2) commitments by the FHLB to make payments required by law or regulation and the level of such payments in relation to the operating performance of the FHLB, (3) the impact of legislative and regulatory changes on institutions and, accordingly, the customer base of the FHLB, and (4) the liquidity position of the FHLB. As a member of the FHLB system, the Bank is required to maintain a minimum level of investment in FHLB stock based on specific percentages of its outstanding mortgages, total assets, or FHLB advances. The Bank may request redemption at par value of any stock in excess of the minimum required investment. Stock redemptions are at the discretion of the FHLB.
Loans Held for Sale	Loans Held for Sale Loans originated and intended for sale in the secondary market are carried at the lower of aggregate cost or fair value, as determined by aggregate outstanding commitments from investors of current investor yield requirements. Net unrealized losses are recognized through a valuation allowance by charges to noninterest income. Mortgage loans held for sale are generally sold with the mortgage servicing rights retained by the Company. Gains or losses on the sale of loans that are held for sale are recognized at the time of the sale and determined by the difference between net sale proceeds and the net book value of the loans less the estimated fair value of any retained mortgage servicing rights.
Loans and Allowance for Loan Losses	Loans and Allowance for Loan Losses Loans originated by the Company, i.e., not purchased or acquired in a business combination, are referred to as originated loans. Originated loans that management has the intent and ability to hold for the foreseeable future or until maturity or payoff are reported at the principal amount outstanding, net of deferred loan fees and costs. Loan origination and commitment fees and certain direct loan origination costs are deferred, and the net amount is amortized as an adjustment of the related loan’s yield over the actual life of the loan. Originated loans on which the accrual of interest has been discontinued are designated as nonaccrual loans. Originated loans are placed in nonaccrual status when reasonable doubt exists as to the full, timely collection of interest or principal, or a loan becomes contractually past due by 90 days or more with respect to interest or principal and is not well secured and in the process of collection. When an originated loan is placed on nonaccrual status, all interest previously accrued but not collected is reversed. Income on such loans is then recognized only to the extent that cash is received and where the future collection of principal is probable. Interest accruals are resumed on such loans only when they are brought fully current with respect to interest and principal and when, in the judgment of Management, the loan is estimated to be fully collectible as to both principal and interest. An allowance for loan losses for originated loans is established through a provision for loan losses charged to expense. The allowance is maintained at a level which, in Management’s judgment, is adequate to absorb probable incurred credit losses inherent in the loan portfolio as of the balance sheet date. Originated loans and deposit related overdrafts are charged against the allowance for loan losses when Management believes that the collectability of the principal is unlikely or, with respect to consumer installment loans, according to an established delinquency schedule. The allowance is an amount that Management believes will be adequate to absorb probable incurred losses inherent in existing loans, based on evaluations of the collectability, impairment and prior loss experience of loans. The evaluations take into consideration such factors as changes in the nature and size of the portfolio, overall portfolio quality, loan concentrations, specific problem loans, and current economic conditions that may affect the borrower’s ability to pay. The Company defines an originated loan as impaired when it is probable the Company will be unable to collect all amounts due according to the original contractual terms of the loan agreement. Impaired originated loans are measured based on the present value of expected future cash flows discounted at the loan’s original effective interest rate. As a practical expedient, impairment may be measured based on the loan’s observable market price or the fair value of the collateral if the loan is collateral dependent. When the measure of the impaired loan is less than the recorded investment in the loan, the impairment is recorded through a specific reserve allocation within the allowance for loan losses. In situations related to originated loans where, for economic or legal reasons related to a borrower’s financial difficulties, the Company grants a concession for other than an insignificant period of time to the borrower that the Company would not otherwise consider, the related loan is classified as a troubled debt restructuring (TDR). The Company strives to identify borrowers in financial difficulty early and work with them to modify to more affordable terms before their loan reaches nonaccrual status. These modified terms may include rate reductions, principal forgiveness, payment forbearance and other actions intended to minimize the economic loss and to avoid foreclosure or repossession of the collateral. In cases where the Company grants the borrower new terms that result in the loan being classified as a TDR, the Company measures any impairment on the restructuring as noted above for impaired loans. TDR loans are classified as impaired until they are fully paid off or charged off. Loans that are in nonaccrual status at the time they become TDR loans, remain in nonaccrual status until the borrower demonstrates a sustained period of performance which the Company generally believes to be six consecutive months of payments, or equivalent. Otherwise, TDR loans are subject to the same nonaccrual and charge-off Credit risk is inherent in the business of lending. As a result, the Company maintains an allowance for loan losses to absorb probable incurred losses inherent in the Company’s originated loan portfolio. This is maintained through periodic charges to earnings. These charges are included in the Consolidated Statements of Income as provision for loan losses. All specifically identifiable and quantifiable losses are immediately charged off against the allowance. However, for a variety of reasons, not all losses are immediately known to the Company and, of those that are known, the full extent of the loss may not be quantifiable at that point in time. The balance of the Company’s allowance for originated loan losses is meant to be an estimate of these probable incurred losses inherent in the portfolio. The Company formally assesses the adequacy of the allowance for originated loan losses on a quarterly basis. Determination of the adequacy is based on ongoing assessments of the probable risk in the outstanding originated loan portfolio, and to a lesser extent the Company’s originated loan commitments. These assessments include the periodic re-grading re-graded Re-grading The Company’s method for assessing the appropriateness of the allowance for originated loan losses includes specific allowances for impaired originated loans, formula allowance factors for pools of credits, and allowances for changing environmental factors (e.g., interest rates, growth, economic conditions, etc.). Allowance factors for loan pools were based on historical loss experience by product type and prior risk rating. Loans purchased or acquired in a business combination are referred to as acquired loans. Acquired loans are valued as of the acquisition date in accordance with Financial Accounting Standards Board Accounting Standards Codification (“FASB ASC”) Topic 805, Business Combinations 310-30, Loans and Debt Securities Acquired with Deteriorated Credit Quality 310-30, 310-30 310-30 Acquired loans that are not PCI loans are referred to as purchased not credit impaired (PNCI) loans. PNCI loans are accounted for under FASB ASC Topic 310-20, Receivables – Nonrefundable Fees and Other Costs, 310-20, Throughout these financial statements, and in particular in Note 4 and Note 5, when we refer to “Loans” or “Allowance for loan losses” we mean all categories of loans, including Originated, PNCI, PCI – cash basis, and PCI – other. When we are not referring to all categories of loans, we will indicate which we are referring to – Originated, PNCI, PCI – cash basis, or PCI – other. When referring to PNCI and PCI loans we use the terms “nonaccretable difference”, “accretable yield”, or “purchase discount”. Nonaccretable difference is the difference between undiscounted contractual cash flows due and undiscounted cash flows we expect to collect, or put another way, it is the undiscounted contractual cash flows we do not expect to collect. Accretable yield is the difference between undiscounted cash flows we expect to collect and the value at which we have recorded the loan on our financial statements. On the date of acquisition, all purchased loans are recorded on our consolidated financial statements at estimated fair value. Purchase discount is the difference between the estimated fair value of loans on the date of acquisition and the principal amount owed by the borrower, net of charge offs, on the date of acquisition. We may also refer to “discounts to principal balance of loans owed, net of charge-offs”. Discounts to principal balance of loans owed, net of charge-offs is the difference between principal balance of loans owed, net of charge-offs, and loans as recorded on our financial statements. Discounts to principal balance of loans owed, net of charge-offs arise from purchase discounts, and equal the purchase discount on the acquisition date. Loans are also categorized as “covered” or “noncovered”. Covered loans refer to loans covered by a Federal Deposit Insurance Corporation (“FDIC”) loss sharing agreement. Noncovered loans refer to loans not covered by a FDIC loss sharing agreement.
Foreclosed Assets	Foreclosed Assets Foreclosed assets include assets acquired through, or in lieu of, loan foreclosure. Foreclosed assets are held for sale and are initially recorded at fair value less estimated costs to sell at the date of foreclosure, establishing a new cost basis. Physical possession of residential real estate property collateralizing a consumer mortgage loan occurs when legal title is obtained upon completion of foreclosure or when the borrower conveys all interest in the property to satisfy the loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. Any write-downs based on the asset’s fair value less costs to sell at the date of acquisition are charged to the allowance for loan and lease losses. Any recoveries based on the asset’s fair value less estimated costs to sell in excess of the recorded value of the loan at the date of acquisition are recorded to the allowance for loan and lease losses. These assets are subsequently accounted for at lower of cost or fair value less estimated costs to sell. If fair value declines subsequent to foreclosure, a valuation allowance is recorded through expense. Operating costs after acquisition are expensed. Revenue and expenses from operations and changes in the valuation allowance are included in other noninterest expense. Gain or loss on sale of foreclosed assets is included in noninterest income. Foreclosed assets that are not subject to a FDIC loss-share agreement are referred to as noncovered foreclosed assets. Foreclosed assets acquired through FDIC-assisted acquisitions that are subject to a FDIC loss-share agreement, and all assets acquired via foreclosure of covered loans are referred to as covered foreclosed assets. Covered foreclosed assets are reported exclusive of expected reimbursement cash flows from the FDIC. Foreclosed covered loan collateral is transferred into covered foreclosed assets at the loan’s carrying value, inclusive of the acquisition date fair value discount. Covered foreclosed assets are initially recorded at estimated fair value less estimated costs to sell on the acquisition date based on similar market comparable valuations less estimated selling costs. Any subsequent valuation adjustments due to declines in fair value will be charged to noninterest expense, and will be mostly offset by noninterest income representing the corresponding increase to the FDIC indemnification asset for the offsetting loss reimbursement amount. Any recoveries of previous valuation adjustments will be credited to noninterest expense with a corresponding charge to noninterest income for the portion of the recovery that is due to the FDIC.
Premises and Equipment	Premises and Equipment Land is carried at cost. Land improvements, buildings and equipment, including those acquired under capital lease, are stated at cost less accumulated depreciation and amortization. Depreciation and amortization expenses are computed using the straight-line method over the shorter of the estimated useful lives of the related assets or lease terms. Asset lives range from 3-10 15-40
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets Goodwill represents the excess of costs over fair value of net assets of businesses acquired. Goodwill and other intangible assets acquired in a business combination and determined to have an indefinite useful life are not amortized, but instead tested for impairment at least annually. Intangible assets with estimable useful lives are amortized over their respective estimated useful lives to their estimated residual values, and reviewed for impairment. The Company has an identifiable intangible asset consisting of core deposit intangibles (CDI). CDI are amortized over their respective estimated useful lives, and reviewed for impairment.
Impairment of Long-Lived Assets and Goodwill	Impairment of Long-Lived Assets and Goodwill Long-lived assets, such as premises and equipment, and purchased intangibles subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its estimated future cash flows, an impairment charge is recognized by the amount by which the carrying amount of the asset exceeds the fair value of the asset. Assets to be disposed of would be separately presented in the balance sheet and reported at the lower of the carrying amount or fair value less costs to sell, and are no longer depreciated. The assets and liabilities of a disposed group classified as held for sale would be presented separately in the appropriate asset and liability sections of the consolidated balance sheet. As of December 31 of each year, goodwill is tested for impairment, and is tested for impairment more frequently if events and circumstances indicate that the asset might be impaired. An impairment loss is recognized to the extent that the carrying amount exceeds the asset’s fair value. This determination is made at the reporting unit level. The Company may choose to first assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If, after assessing the totality of events or circumstances, the Company determines it is not more likely than not that the fair value of a reporting unit is less than its carrying amount, then goodwill is deemed not to be impaired. However, if the Company concludes otherwise, or if the Company elected not to first assess qualitative factors, then the Company performs the first step of a two-step
Mortgage Servicing Rights	Mortgage Servicing Rights Mortgage servicing rights (MSR) represent the Company’s right to a future stream of cash flows based upon the contractual servicing fee associated with servicing mortgage loans. Our MSR arise from residential and commercial mortgage loans that we originate and sell, but retain the right to service the loans. The net gain from the retention of the servicing right is included in gain on sale of loans in noninterest income when the loan is sold. Fair value is based on market prices for comparable mortgage servicing contracts, when available, or alternatively, is based on a valuation model that calculates the present value of estimated future net servicing income. The valuation model incorporates assumptions that market participants would use in estimating future net servicing income, such as the cost to service, the discount rate, the custodial earnings rate, an inflation rate, ancillary income, prepayment speeds and default rates and losses. Servicing fees are recorded in noninterest income when earned. The Company accounts for MSR at fair value. The determination of fair value of our MSR requires management judgment because they are not actively traded. The determination of fair value for MSR requires valuation processes which combine the use of discounted cash flow models and extensive analysis of current market data to arrive at an estimate of fair value. The cash flow and prepayment assumptions used in our discounted cash flow model are based on empirical data drawn from the historical performance of our MSR, which we believe are consistent with assumptions used by market participants valuing similar MSR, and from data obtained on the performance of similar MSR. The key assumptions used in the valuation of MSR include mortgage prepayment speeds and the discount rate. These variables can, and generally will, change from quarter to quarter as market conditions and projected interest rates change. The key risks inherent with MSR are prepayment speed and changes in interest rates. The Company uses an independent third party to determine fair value of MSR.
Indemnification Asset/Liability	Indemnification Asset/Liability The Company accounts for amounts receivable or payable under its loss-share agreements entered into with the FDIC in connection with its purchase and assumption of certain assets and liabilities of Granite as indemnification assets in accordance with FASB ASC Topic 805, Business Combinations
Reserve for Unfunded Commitments	Reserve for Unfunded Commitments The reserve for unfunded commitments is established through a provision for losses – unfunded commitments charged to noninterest expense. The reserve for unfunded commitments is an amount that Management believes will be adequate to absorb probable losses inherent in existing commitments, including unused portions of revolving lines of credit and other loans, standby letters of credit, and unused deposit account overdraft privileges. The reserve for unfunded commitments is based on evaluations of the collectability, and prior loss experience of unfunded commitments. The evaluations take into consideration such factors as changes in the nature and size of the loan portfolio, overall loan portfolio quality, loan concentrations, specific problem loans and related unfunded commitments, and current economic conditions that may affect the borrower’s or depositor’s ability to pay.
Low Income Housing Tax Credits	Low Income Housing Tax Credits The Company accounts for low income housing tax credits and the related qualified affordable housing projects using the proportional amortization method. Under the proportional amortization method, the Company amortizes the initial cost of the investment in proportion to the tax credits and other tax benefits received and recognizes the net investment performance in the income statement as a component of income tax expense (benefit). Upon entering into a qualified affordable housing project, the Company records, in other liabilities, the entire amount that it has agreed to invest in the project, and an equal amount, in other assets, representing its investment in the project. As the Company disburses cash to satisfy its investment obligation, other liabilities are reduced. Over time, as the tax credits and other tax benefits of the project are realized by the Company, the investment recorded in other assets is reduced using the proportional amortization method.
Income Taxes	Income Taxes The Company’s accounting for income taxes is based on an asset and liability approach. The Company recognizes the amount of taxes payable or refundable for the current year, and deferred tax assets and liabilities for the future tax consequences that have been recognized in its financial statements or tax returns. The measurement of tax assets and liabilities is based on the provisions of enacted tax laws. A valuation allowance, if needed, reduces deferred tax assets to the expected amount most likely to be realized. Realization of deferred tax assets is dependent upon the generation of a sufficient level of future taxable income and recoverable taxes paid in prior years. Although realization is not assured, management believes it is more likely than not that all of the deferred tax assets will be realized. Interest and/or penalties related to income taxes are reported as a component of noninterest income.
Off-Balance Sheet Credit Related Financial Instruments	Off-Balance In the ordinary course of business, the Company has entered into commitments to extend credit, including commitments under credit card arrangements, commercial letters of credit, and standby letters of credit. Such financial instruments are recorded when they are funded.
Geographical Descriptions	Geographical Descriptions For the purpose of describing the geographical location of the Company’s loans, the Company has defined northern California as that area of California north of, and including, Stockton; central California as that area of the state south of Stockton, to and including, Bakersfield; and southern California as that area of the state south of Bakersfield.
Reclassifications	Reclassifications During the three months ended September 30, 2017, the Company changed its classification of 1 st nd non-owner 1-4 0.10%-0.20% total loans
Recent Accounting Pronouncements	Recent Accounting Pronouncements FASB Accounting Standards Update (ASU) No.2014-09, Revenue from Contracts with Customers (Topic 606): 2014-09 2014-09 2014-09 2014-09 ASU 2014-09 FASB issued Accounting Standard Update (ASU) No. 2016-02 , Leases (Topic 842) ASU 2016-2, on-balance ASU 2016-02 FASB issued Accounting Standard Update (ASU) No. 2016-09 , Compensation – Stock Compensation (Topic 718). ASU 2016-09, ASU 2016-09 FASB issued ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326) 2016-13 2016-13, 2016-13 available-for-sale 2016-13 2016-13 2016-13 2016-13 one-time one-time FASB issued ASU No. 2016-18, Statement of Cash Flows - Restricted Cash (Topic 230). ASU 2016-18 beginning-of-period end-of-period ASU 2016-18 FASB issued ASU No. 2017-01, Business Combinations - Clarifying the Definition of a Business (Topic 805). ASU 2017-01 ASU 2017-01 ASU 2017-01 FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other: Simplifying the Test for Goodwill Impairment (Topic 350). 2017-04 ASU 2017-04 FASB issued ASU No. 2017-07, Compensation - Retirement Benefits (Topic 715). 2017-07 ASU 2017-07 FASB issued ASU 2017-08, Receivables - Nonrefundable Fees and Other Costs (Topic 310). ASU 2017-08 non-pooled ASU 2017-08 ASU 2017-08 FASB issued ASU 2017-09, Compensation - Stock Compensation (Topic 718). ASU 2017-09 ASU 2017-09, ASU 2017-09 FASB issued ASU 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220 ) . 2018-02 2018-02 2018-02

Business Combinations (Tables)

Business Combinations (Tables) - Bank of America [Member]	12 Months Ended
	Dec. 31, 2017
Schedule of Fair Value of Consideration Transferred, Identifiable Net Assets Acquired and Resulting Goodwill	The following table discloses the calculation of the fair value of consideration transferred, the total identifiable net assets acquired and the resulting goodwill relating to the acquisition of three branch banking offices and certain deposits from Bank of America on March 18, 2016: (in thousands) March 18, 2016 Fair value of consideration transferred: Cash consideration $ 3,204 Total fair value of consideration transferred 3,204 Asset acquired: Cash and cash equivalents 159,520 Loans 289 Premises and equipment 1,590 Core deposit intangible 2,046 Other assets 141 Total assets acquired 163,586 Liabilities assumed: Deposits 161,231 Total liabilities assumed 161,231 Total net assets acquired 2,355 Goodwill recognized $ 849
Summary of Cash Paid and Estimated Fair Value Adjustments Resulting in Goodwill	A summary of the cash paid and estimated fair value adjustments resulting in the goodwill recorded in the acquisition of three branch banking offices and certain deposits from Bank of America on March 18, 2016 are presented below: (in thousands) March 18, 2016 Cash paid $ 3,204 Cost basis net assets acquired — Fair value adjustments: Loans — Premises and Equipment (309 ) Core deposit intangible (2,046 ) Goodwill $ 849

Investment Securities (Tables)

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2017
Investments Schedule [Abstract]
Amortized Cost and Estimated Fair Values of Investments in Debt and Equity Securities	The amortized cost and estimated fair values of investments in debt and equity securities are summarized in the following tables: December 31, 2017 Amortized Gross Gross Estimated (in thousands) Securities Available for Sale Obligations of U.S. government corporations and agencies $ 609,695 $ 695 $ (5,601 ) $ 604,789 Obligations of states and political subdivisions 121,597 1,888 (329 ) 123,156 Marketable equity securities 3,000 — (62 ) 2,938 Total securities available for sale $ 734,292 $ 2,583 $ (5,992 ) $ 730,883 Securities Held to Maturity Obligations of U.S. government corporations and agencies $ 500,271 $ 5,101 $ (1,889 ) $ 503,483 Obligations of states and political subdivisions 14,573 146 (37 ) 14,682 Total securities held to maturity $ 514,844 $ 5,247 $ (1,926 ) $ 518,165 December 31, 2016 Amortized Gross Gross Estimated (in thousands) Securities Available for Sale Obligations of U.S. government corporations and agencies $ 434,357 $ 1,949 $ (6,628 ) $ 429,678 Obligations of states and political subdivisions 121,746 267 (4,396 ) 117,617 Marketable equity securities 3,000 — (62 ) 2,938 Total securities available for sale $ 559,103 $ 2,216 $ (11,086 ) $ 550,233 Securities Held to Maturity Obligations of U.S. government corporations and agencies $ 587,982 $ 5,001 $ (4,199 ) $ 588,784 Obligations of states and political subdivisions 14,554 56 (191 ) 14,419 Total securities held to maturity $ 602,536 $ 5,057 $ (4,390 ) $ 603,203
Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity	For purposes of the following table, the entire outstanding balance of these mortgage-backed securities issued by U.S. government corporations and agencies is categorized based on final maturity date. Available for Sale Held to Maturity Investment Securities (In thousands) Amortized Estimated Amortized Estimated Due in one year $ 2 $ 2 — — Due after one year through five years 211 211 $ 1,207 $ 1,226 Due after five years through ten years 2,231 2,281 14,011 14,067 Due after ten years 731,848 728,389 499,626 502,872 Totals $ 734,292 $ 730,883 $ 514,844 $ 518,165
Gross Unrealized Losses on Investment	Gross unrealized losses on investment securities and the fair value of the related securities, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, were as follows: Less than 12 months 12 months or more Total December 31, 2017: Fair Unrealized Fair Unrealized Fair Unrealized (in thousands) Securities Available for Sale Obligations of U.S. government corporations and agencies $ 284,367 $ (2,176 ) $ 166,338 $ (3,425 ) $ 450,705 $ (5,601 ) Obligations of states and political subdivisions 4,904 (35 ) 17,085 (294 ) 21,989 (329 ) Marketable equity securities — — 2,938 (62 ) 2,938 (62 ) Total securities available-for-sale $ 289,271 $ (2,211 ) $ 186,361 $ (3,781 ) $ 475,632 $ (5,992 ) Securities Held to Maturity Obligations of U.S. government corporations and agencies $ 93,017 $ (567 ) $ 95,367 $ (1,322 ) $ 188,384 $ (1,889 ) Obligations of states and political subdivisions 1,488 (7 ) 2,637 (30 ) 4,125 (37 ) Total securities held-to-maturity $ 94,505 $ (574 ) $ 98,004 $ (1,352 ) $ 192,509 $ (1,926 ) Less than 12 months 12 months or more Total December 31, 2016: Fair Unrealized Fair Unrealized Fair Unrealized (in thousands) Securities Available for Sale Obligations of U.S. government corporations and agencies $ 370,389 $ (6,628 ) — — $ 370,389 $ (6,628 ) Obligations of states and political subdivisions 90,825 (4,396 ) — — 90,825 (4,396 ) Marketable equity securities 2,938 (62 ) — — 2,938 (62 ) Total securities available-for-sale $ 464,152 $ (11,086 ) — — $ 464,152 $ (11,086 ) Securities Held to Maturity Obligations of U.S. government corporations and agencies $ 280,497 $ (4,199 ) — — $ 280,497 $ (4,199 ) Obligations of states and political subdivisions 9,984 (191 ) — — 9,984 (191 ) Total securities held-to-maturity $ 290,481 $ (4,390 ) — — $ 290,481 $ (4,390 )

Loans (Tables)

Loans (Tables)	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Summary of Loan Balances	A summary of loan balances follows (in thousands): December 31, 2017 Originated PNCI PCI - PCI - Total Mortgage loans on real estate: Residential 1-4 $ 320,522 $ 63,519 — $ 1,385 $ 385,426 Commercial 1,690,510 215,823 — 8,563 1,914,896 Total mortgage loan on real estate 2,011,032 279,342 — 9,948 2,300,322 Consumer: Home equity lines of credit 269,942 16,248 2,069 429 288,688 Home equity loans 39,848 2,698 — 485 43,031 Other 22,859 2,251 — 45 25,155 Total consumer loans 332,649 21,197 2,069 959 356,874 Commercial 209,437 8,391 — 2,584 220,412 Construction: Residential 67,920 10 — — 67,930 Commercial 69,364 263 — — 69,627 Total construction 137,284 273 — — 137,557 Total loans, net of deferred loan fees and discounts $ 2,690,402 $ 309,203 $ 2,069 $ 13,491 $ 3,015,165 Total principal balance of loans owed, net of charge-offs $ 2,699,053 $ 316,238 $ 5,863 $ 17,318 $ 3,038,472 Unamortized net deferred loan fees (8,651 ) — — — (8,651 ) Discounts to principal balance of loans owed, net of charge-offs — (7,035 ) (3,794 ) (3,827 ) (14,656 ) Total loans, net of unamortized deferred loan fees and discounts $ 2,690,402 $ 309,203 $ 2,069 $ 13,491 $ 3,015,165 Noncovered loans $ 2,690,402 $ 309,203 $ 2,069 $ 13,491 $ 3,015,165 Covered loans — — — — — Total loans, net of unamortized deferred loan fees and discounts $ 2,690,402 $ 309,203 $ 2,069 $ 13,491 $ 3,015,165 Allowance for loan losses $ (29,122 ) $ (929 ) $ (17 ) $ (255 ) $ (30,323 ) A summary of loan balances follows (in thousands): December 31, 2016 Originated PNCI PCI - PCI - Total Mortgage loans on real estate: Residential 1-4 $ 284,539 $ 82,335 — $ 1,469 $ 368,343 Commercial 1,425,828 246,491 — 12,802 1,685,121 Total mortgage loan on real estate 1,710,367 328,826 — 14,271 2,053,464 Consumer: Home equity lines of credit 263,590 21,765 2,983 1,377 289,715 Home equity loans 40,736 3,764 — 1,682 46,182 Other 28,167 2,534 — 65 30,766 Total consumer loans 332,493 28,063 2,983 3,124 366,663 Commercial 200,735 12,321 — 3,991 217,047 Construction: Residential 54,613 141 — 675 55,429 Commercial 58,119 8,871 — — 66,990 Total construction 112,732 9,012 — 675 122,419 Total loans, net of deferred loan fees and discounts $ 2,356,327 $ 378,222 $ 2,983 $ 22,061 $ 2,759,593 Total principal balance of loans owed, net of charge-offs $ 2,363,243 $ 388,139 $ 8,280 $ 25,650 $ 2,785,312 Unamortized net deferred loan fees (6,916 ) — — — (6,916 ) Discounts to principal balance of loans owed, net of charge-offs — (9,917 ) (5,297 ) (3,589 ) (18,803 ) Total loans, net of unamortized deferred loan fees and discounts $ 2,356,327 $ 378,222 $ 2,983 $ 22,061 $ 2,759,593 Noncovered loans $ 2,356,327 $ 378,222 $ 2,983 $ 18,885 $ 2,756,417 Covered loans — — — 3,176 3,176 Total loans, net of unamortized deferred loan fees and discounts $ 2,356,327 $ 378,222 $ 2,983 $ 22,061 $ 2,759,593 Allowance for loan losses $ (28,141 ) $ (1,665 ) $ (17 ) $ (2,680 ) $ (32,503 )
Change in Accretable Yield for PCI	The following is a summary of the change in accretable yield for PCI – other loans during the periods indicated (in thousands): Year ended December 31, 2017 2016 Change in accretable yield: Balance at beginning of period $ 10,348 $ 13,255 Accretion to interest income (2,809 ) (4,011 ) Reclassification (to) from nonaccretable difference (3,277 ) 1,104 Balance at end of period $ 4,262 $ 10,348

Allowance for Loan Losses (Tabl

Allowance for Loan Losses (Tables)	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Summary of Activity in Allowance for Loan Losses, and Ending Balance of Loans, Net of Unearned Fees for Periods Indicated	The following tables summarize the activity in the allowance for loan losses, and ending balance of loans, net of unearned fees for the periods indicated. Allowance for Loan Losses - Year Ended December 31, 2017 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Beginning balance $ 2,748 $ 11,517 $ 7,044 $ 2,644 — $ 622 $ 5,831 $ 1,417 $ 680 $ 32,503 Charge-offs (60 ) (186 ) (98 ) (332 ) — (1,186 ) (1,444 ) (1,104 ) — (4,410 ) Recoveries — 397 698 242 — 375 428 — 1 2,141 (Benefit) provision (371 ) (287 ) (1,844 ) (713 ) — 775 1,697 871 (39 ) 89 Ending balance $ 2,317 $ 11,441 $ 5,800 $ 1,841 — $ 586 $ 6,512 $ 1,184 $ 642 $ 30,323 Ending balance: Individ. evaluated for impairment $ 230 $ 30 $ 427 $ 107 — $ 57 $ 1,848 — — $ 2,699 Loans pooled for evaluation $ 1,932 $ 11,351 $ 5,356 $ 1,734 — $ 529 $ 4,624 $ 1,184 $ 642 $ 27,352 Loans acquired with deteriorated credit quality $ 155 $ 60 $ 17 — — — $ 40 — — $ 272 Loans, net of unearned fees – As of December 31, 2017 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Ending balance: Total loans $ 385,426 $ 1,914,896 $ 288,688 $ 43,031 — $ 25,155 $ 220,412 $ 67,930 $ 69,627 $ 3,015,165 Individ. evaluated for impairment $ 5,298 $ 13,911 $ 2,688 $ 1,470 — $ 257 $ 4,470 $ 140 — $ 28,234 Loans pooled for evaluation $ 378,743 $ 1,892,422 $ 283,502 $ 41,076 — $ 24,853 $ 213,358 $ 67,790 $ 69,627 $ 2,971,371 Loans acquired with deteriorated credit quality $ 1,385 $ 8,563 $ 2,498 $ 485 — $ 45 $ 2,584 — — $ 15,560 Allowance for Loan Losses - Year Ended December 31, 2016 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Beginning balance $ 2,896 $ 11,015 $ 11,253 $ 3,177 — $ 688 $ 5,271 $ 899 $ 812 $ 36,011 Charge-offs (321 ) (827 ) (585 ) (219 ) — (823 ) (455 ) — — (3,230 ) Recoveries 880 920 2,317 590 — 449 404 54 78 5,692 (Benefit) provision (707 ) 409 (5,941 ) (904 ) — 308 611 464 (210 ) (5,970 ) Ending balance $ 2,748 $ 11,517 $ 7,044 $ 2,644 — $ 622 $ 5,831 $ 1,417 $ 680 $ 32,503 Ending balance: Individ. evaluated for impairment $ 258 $ 4 $ 411 $ 215 — $ 28 $ 1,130 — — $ 2,046 Loans pooled for evaluation $ 2,304 $ 10,064 $ 6,616 $ 2,365 — $ 594 $ 3,765 $ 1,372 $ 680 $ 27,760 Loans acquired with deteriorated credit quality $ 186 $ 1,449 $ 17 $ 64 — — $ 936 $ 45 — $ 2,697 Loans, net of unearned fees – As of December 31, 2016 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Ending balance: Total loans $ 368,343 $ 1,685,121 $ 289,715 $ 46,182 — $ 30,766 $ 217,047 $ 55,429 $ 66,990 $ 2,759,593 Individ. evaluated for impairment $ 4,094 $ 15,081 $ 3,196 $ 1,508 — $ 154 $ 4,096 $ 11 — $ 28,140 Loans pooled for evaluation $ 362,780 $ 1,657,238 $ 282,159 $ 42,992 — $ 30,547 $ 208,960 $ 54,743 $ 66,990 $ 2,706,409 Loans acquired with deteriorated credit quality $ 1,469 $ 12,802 $ 4,360 $ 1,682 — $ 65 $ 3,991 $ 675 — $ 25,044 Allowance for Loan Losses - Year Ended December 31, 2015 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Beginning balance $ 3,086 $ 9,227 $ 15,676 $ 1,797 $ 9 $ 719 $ 4,226 $ 1,434 $ 411 $ 36,585 Charge-offs (224 ) — (694 ) (242 ) (4 ) (972 ) (680 ) — — (2,816 ) Recoveries 204 243 666 252 42 500 677 1,728 140 4,452 (Benefit) provision (170 ) 1,545 (4,395 ) 1,370 (47 ) 441 1,048 (2,263 ) 261 (2,210 ) Ending balance $ 2,896 $ 11,015 $ 11,253 $ 3,177 — $ 688 $ 5,271 $ 899 $ 812 $ 36,011 Ending balance: Individ. evaluated for impairment $ 335 $ 396 $ 605 $ 294 — $ 74 $ 1,187 — — $ 2,891 Loans pooled for evaluation $ 2,501 $ 9,167 $ 10,423 $ 2,883 — $ 614 $ 2,983 $ 844 $ 812 $ 30,227 Loans acquired with deteriorated credit quality $ 60 $ 1,452 $ 225 — — — $ 1,101 $ 55 — $ 2,893 Loans, net of unearned fees – As of December 31, 2015 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Ending balance: Total loans $ 314,265 $ 1,497,567 $ 322,492 $ 40,362 — $ 32,429 $ 194,913 $ 46,135 $ 74,774 $ 2,522,937 Individ. evaluated for impairment $ 6,767 $ 32,407 $ 5,747 $ 1,731 — $ 288 $ 2,671 $ 4 $ 490 $ 50,105 Loans pooled for evaluation $ 305,353 $ 1,442,100 $ 309,007 $ 37,004 — $ 32,077 $ 187,393 $ 45,410 $ 74,284 $ 2,432,628 Loans acquired with deteriorated credit quality $ 2,145 $ 23,060 $ 7,738 $ 1,627 — $ 64 $ 4,849 $ 721 — $ 40,204
Presentation of Credit Quality Indicators	The following tables present ending loan balances by loan category and risk grade for the periods indicated: Credit Quality Indicators – As of December 31, 2017 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Originated loans: Pass $ 315,120 $ 1,649,333 $ 265,345 $ 37,428 — $ 22,432 $ 195,208 $ 67,813 $ 64,492 $ 2,617,171 Special mention 2,234 18,434 2,558 800 — 272 9,492 — 4,872 38,662 Substandard 3,168 22,743 2,039 1,620 — 155 4,737 107 — 34,569 Loss — — — — — — — — — — Total originated $ 320,522 $ 1,690,510 $ 269,942 $ 39,848 — $ 22,859 $ 209,437 $ 67,920 $ 69,364 $ 2,690,402 PNCI loans: Pass $ 61,411 $ 203,751 $ 14,866 $ 2,433 — $ 2,207 $ 8,390 $ 10 $ 263 $ 293,331 Special mention 218 11,513 450 188 — 38 1 — — 12,408 Substandard 1,890 559 932 77 — 6 — — — 3,464 Loss — — — — — — — — — — Total PNCI $ 63,519 $ 215,823 $ 16,248 $ 2,698 — $ 2,251 $ 8,391 $ 10 $ 263 $ 309,203 PCI loans $ 1,385 $ 8,563 $ 2,498 $ 485 — $ 45 $ 2,584 — — $ 15,560 Total loans $ 385,426 $ 1,914,896 $ 288,688 $ 43,031 — 25,155 $ 220,412 $ 67,930 $ 69,627 $ 3,015,165 Credit Quality Indicators – As of December 31, 2016 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Originated loans: Pass $ 278,635 $ 1,399,936 $ 258,024 $ 37,844 — $ 27,542 $ 190,902 $ 54,602 $ 57,808 $ 2,305,293 Special mention 2,992 14,341 2,518 891 — 385 6,133 — 311 27,571 Substandard 2,912 11,551 3,048 2,001 — 240 3,700 11 — 23,463 Loss — — — — — — — — — — Total originated $ 284,539 $ 1,425,828 $ 263,590 $ 40,736 — $ 28,167 $ 200,735 $ 54,613 $ 58,119 $ 2,356,327 PNCI loans: Pass $ 79,000 $ 233,326 $ 20,442 $ 3,506 — $ 2,437 $ 12,320 $ 141 $ 8,871 $ 360,043 Special mention 1,849 5,925 509 173 — 92 1 — — 8,549 Substandard 1,486 7,240 814 85 — 5 — — — 9,630 Loss — — — — — — — — — — Total PNCI $ 82,335 $ 246,491 $ 21,765 $ 3,764 — $ 2,534 $ 12,321 $ 141 $ 8,871 $ 378,222 PCI loans $ 1,469 $ 12,802 $ 4,360 $ 1,682 — $ 65 $ 3,991 $ 675 — $ 25,044 Total loans $ 368,343 $ 1,685,121 $ 289,715 $ 46,182 — $ 30,766 $ 217,047 $ 55,429 $ 66,990 $ 2,759,593
Analysis of Past Due and Nonaccrual Loans	The following table shows the ending balance of current, past due, and nonaccrual originated loans by loan category as of the date indicated: Analysis of Past Due and Nonaccrual Originated Loans – As of December 31, 2017 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Originated loan balance: Past due: 30-59 Days $ 1,740 $ 158 $ 528 $ 511 — $ 56 $ 956 $ 34 — $ 3,983 60-89 Days 510 987 48 107 — 36 738 — — 2,426 > 90 Days 243 — 372 373 — 3 1,527 — — 2,518 Total past due $ 2,493 $ 1,145 $ 948 $ 991 — $ 95 $ 3,221 $ 34 — $ 8,927 Current 318,029 1,689,365 268,994 38,857 — 22,764 206,216 67,886 $ 69,364 2,681,475 Total orig. loans $ 320,522 $ 1,690,510 $ 269,942 $ 39,848 — $ 22,859 $ 209,437 $ 67,920 $ 69,364 $ 2,690,402 > 90 Days and still accruing — — — — — — — — — — Nonaccrual loans $ 1,725 $ 8,144 $ 811 $ 1,106 — $ 7 $ 3,669 — — $ 15,462 The following table shows the ending balance of current, past due, and nonaccrual PNCI loans by loan category as of the date indicated: Analysis of Past Due and Nonaccrual PNCI Loans – As of December 31, 2017 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total PNCI loan balance: Past due: 30-59 Days $ 1,495 $ 70 $ 298 $ 30 — $ 6 — — — $ 1,899 60-89 Days 90 — 228 — — 26 — — — 344 > 90 Days 109 — 330 — — — — — — 439 Total past due $ 1,694 $ 70 $ 856 $ 30 — $ 32 — — — $ 2,682 Current 61,825 215,753 15,392 2,668 — 2,219 $ 8,391 $ 10 $ 263 306,521 Total PNCI loans $ 63,519 $ 215,823 $ 16,248 $ 2,698 — $ 2,251 $ 8,391 $ 10 $ 263 $ 309,203 > 90 Days and still accruing $ 81 — $ 200 — — — — — — $ 281 Nonaccrual loans $ 1,012 — $ 402 $ 44 — $ 5 — — — $ 1,463 The following table shows the ending balance of current, past due, and nonaccrual originated loans by loan category as of the date indicated: Analysis of Past Due and Nonaccrual Originated Loans – As of December 31, 2016 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Originated loan balance: Past due: 30-59 $ 552 $ 317 $ 754 $ 646 — $ 16 $ 1,148 $ 921 — $ 4,354 60-89 269 1,387 — 395 — 30 84 — $ 421 2,586 > 90 Days — 216 687 184 — 15 634 11 — 1,747 Total past due $ 821 $ 1,920 $ 1,441 $ 1,225 — $ 61 $ 1,866 $ 932 $ 421 $ 8,687 Current 283,718 1,423,908 262,149 39,511 — 28,106 198,869 53,681 57,698 2,347,640 Total orig. loans $ 284,539 $ 1,425,828 $ 263,590 $ 40,736 — $ 28,167 $ 200,735 $ 54,613 $ 58,119 $ 2,356,327 > 90 Days and still accruing — — — — — — — — — — Nonaccrual loans $ 255 $ 7,651 $ 1,211 $ 803 — $ 33 $ 2,930 $ 11 — $ 12,894 The following table shows the ending balance of current, past due, and nonaccrual PNCI loans by loan category as of the date indicated: Analysis of Past Due and Nonaccrual PNCI Loans – As of December 31, 2016 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total PNCI loan balance: Past due: 30-59 $ 1,510 $ 73 $ 274 $ 39 — — — — — $ 1,896 60-89 — — — — — — — — — — > 90 Days 21 81 589 13 — — — — — 704 Total past due $ 1,531 $ 154 $ 863 $ 52 — — — — — $ 2,600 Current 80,804 246,337 20,902 3,712 — $ 2,534 $ 12,321 $ 141 $ 8,871 375,622 Total PNCI loans $ 82,335 $ 246,491 $ 21,765 $ 3,764 — $ 2,534 $ 12,321 $ 141 $ 8,871 $ 378,222 > 90 Days and still accruing — — — — — — — — — — Nonaccrual loans $ 194 $ 1,826 $ 742 $ 67 — $ 5 — — — $ 2,834
Impaired Loans	Impaired originated loans are those where management has concluded that it is probable that the borrower will be unable to pay all amounts due under the contractual terms. The following tables show the recorded investment (financial statement balance), unpaid principal balance, average recorded investment, and interest income recognized for impaired Originated and PNCI loans, segregated by those with no related allowance recorded and those with an allowance recorded for the periods indicated. Impaired Originated Loans – As of December 31, 2017 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total With no related allowance recorded: Recorded investment $ 2,058 $ 13,101 $ 1,093 $ 1,107 — $ 4 $ 575 $ 140 — $ 18,078 Unpaid principal $ 2,109 $ 13,360 $ 1,175 $ 1,429 — $ 52 $ 585 $ 140 — $ 18,850 Average recorded Investment $ 1,875 $ 13,123 $ 1,287 $ 852 — $ 10 $ 668 $ 76 — $ 17,891 Interest income Recognized $ 85 $ 609 $ 39 $ 14 — — $ 18 $ 9 — $ 774 With an allowance recorded: Recorded investment $ 1,881 $ 810 $ 401 $ 198 — $ 3 $ 3,895 — — $ 7,188 Unpaid principal $ 1,914 $ 826 $ 406 $ 198 — $ 3 $ 3,981 — — $ 7,328 Related allowance $ 230 $ 30 $ 111 $ 10 — $ 3 $ 1,848 — — $ 2,232 Average recorded Investment $ 1,626 $ 728 $ 415 $ 341 — $ 10 $ 3,615 — — $ 6,735 Interest income Recognized $ 58 $ 36 $ 8 $ 10 — — $ 166 — — $ 278 Impaired PNCI Loans – As of December 31, 2017 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total With no related allowance recorded: Recorded investment $ 1,359 — $ 591 $ 44 — — — — — $ 1,994 Unpaid principal $ 1,404 — $ 612 $ 57 — — — — — $ 2,073 Average recorded Investment $ 911 $ 913 $ 663 $ 56 — $ 2 — — — $ 2,545 Interest income Recognized $ 24 — $ 22 — — — — — — $ 46 With an allowance recorded: Recorded investment — — $ 603 $ 121 — $ 250 — — — $ 974 Unpaid principal — — $ 604 $ 121 — $ 250 — — — $ 975 Related allowance — — $ 316 $ 97 — $ 54 — — — $ 467 Average recorded Investment $ 130 $ 66 $ 577 $ 61 — $ 184 — — — $ 1,018 Interest income Recognized — — $ 26 $ 6 — $ 11 — — — $ 43 Impaired Originated Loans – As of December 31, 2016 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total With no related allowance recorded: Recorded investment $ 1,820 $ 12,898 $ 1,480 $ 715 — $ 15 $ 762 $ 11 — $ 17,701 Unpaid principal $ 1,829 $ 13,145 $ 1,561 $ 1,135 — $ 29 $ 926 $ 16 — $ 18,641 Average recorded Investment $ 2,853 $ 20,003 $ 2,221 $ 831 $ 1 $ 16 $ 669 $ 7 — $ 26,601 Interest income Recognized $ 92 $ 570 $ 40 $ 6 — $ 1 $ 48 — — $ 757 With an allowance recorded: Recorded investment $ 1,551 $ 357 $ 430 $ 594 — $ 19 $ 3,334 — — $ 6,285 Unpaid principal $ 1,552 $ 358 $ 440 $ 595 — $ 19 $ 3,385 — — $ 6,349 Related allowance $ 180 $ 4 $ 110 $ 107 — $ 13 $ 1,130 — — $ 1,544 Average recorded Investment $ 1,779 $ 888 $ 1,076 $ 634 — $ 9 $ 2,714 — — $ 7,100 Interest income Recognized $ 65 $ 22 $ 9 $ 31 — $ 2 $ 77 — — $ 206 Impaired PNCI Loans – As of December 31, 2016 RE Mortgage Home Equity Auto Other Construction (in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total With no related allowance recorded: Recorded investment $ 463 $ 1,826 $ 735 $ 67 — $ 3 — — — $ 3,094 Unpaid principal $ 486 $ 2,031 $ 746 $ 74 — $ 4 — — — $ 3,341 Average recorded Investment $ 669 $ 1,479 $ 594 $ 69 — $ 18 $ 1 — $ 245 $ 3,075 Interest income Recognized $ 7 — $ 9 $ 1 — — — — — $ 17 With an allowance recorded: Recorded investment $ 259 — $ 551 $ 132 — $ 118 — — — $ 1,060 Unpaid principal $ 259 — $ 551 $ 132 — $ 118 — — — $ 1,060 Related allowance $ 79 — $ 300 $ 108 — $ 15 — — — $ 502 Average recorded Investment $ 130 $ 1,374 $ 579 $ 85 — $ 176 — — — $ 2,344 Interest income Recognized $ 10 — $ 27 $ 7 — $ 5 — — — $ 49
Troubled Debt Restructurings	The following tables show certain information regarding Troubled Debt Restructurings (TDRs) that occurred during the periods indicated: TDR Information for the Year Ended December 31, 2017 RE Mortgage Home Equity Auto Other Construction (dollars in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Number 1 8 3 1 — 1 11 1 — 26 Pre-mod $ 939 $ 3,721 $ 187 $ 252 — $ 14 $ 1,854 $ 144 — $ 7,111 Post-mod $ 939 $ 3,695 $ 187 $ 252 — $ 14 $ 1,747 $ 144 — $ 6,978 Financial impact due to TDR taken as additional provision $ 169 $ (111 ) $ 27 — — $ 11 $ 37 — — $ 133 Number that defaulted during the period 2 1 1 1 — — — — — 5 Recorded investment of TDRs that subsequently defaulted during the 12 month period after modification $ 223 $ 219 $ 127 $ 55 — — — — — $ 624 Financial impact due to the default of previous TDR taken as charge-offs or additional provisions — — $ (5 ) — — — — — — $ (5 ) TDR Information for the Year Ended December 31, 2016 RE Mortgage Home Equity Auto Other Construction (dollars in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Number 3 5 9 1 — 2 4 — — 24 Pre-mod $ 650 $ 423 $ 707 $ 105 — $ 27 $ 77 — — $ 1,989 Post-mod $ 656 $ 461 $ 709 $ 105 — $ 27 $ 77 — — $ 2,035 Financial impact due to TDR taken as additional provision $ 50 $ 46 $ 205 — — $ 2 $ 23 — — $ 326 Number that defaulted during the period 2 — 1 — — — — — — 3 Recorded investment of TDRs that subsequently defaulted during the 12 month period after modification $ 101 — $ 229 — — — — — — $ 330 Financial impact due to the default of previous TDR taken as charge-offs or additional provisions — — — — — — — — — — TDR Information for the Year Ended December 31, 2015 RE Mortgage Home Equity Auto Other Construction (dollars in thousands) Resid. Comm. Lines Loans Indirect Consum. C&I Resid. Comm. Total Number 4 5 2 2 — 2 8 — — 23 Pre-mod outstanding principal balance $ 800 $ 1,518 $ 301 $ 315 — $ 89 $ 956 — — $ 3,979 Post-mod outstanding principal balance $ 801 $ 1,517 $ 301 $ 321 — $ 89 $ 944 — — $ 3,973 Financial impact due to TDR taken as additional provision $ 8 $ (5 ) — $ 38 $ 5 $ 405 — — $ 451 Number that defaulted during the period 4 2 3 1 — — — — — 10 Recorded investment of TDRs that subsequently defaulted during the 12 month period after modification $ 221 $ 280 $ 182 $ 53 — — — — — $ 736 Financial impact due to the default of previous TDR taken as charge-offs or additional provisions — — — $ (9 ) — — — — — $ (9 )

Foreclosed Assets (Tables)

Foreclosed Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Summary of Activity in Balance of Foreclosed Assets	A summary of the activity in the balance of foreclosed assets follows (dollars in thousands): Year ended December 31, 2017 Year ended December 31, 2016 Noncovered Covered Total Noncovered Covered Total Beginning balance, net $ 3,763 $ 223 $ 3,986 $ 5,369 — $ 5,369 Additions/transfers from loans 1,563 — 1,563 2,282 $ 223 2,505 Dispositions/sales (1,938 ) $ (223 ) (2,161 ) (3,748 ) — (3,748 ) Valuation adjustments (162 ) — (162 ) (140 ) — (140 ) Ending balance, net $ 3,226 — $ 3,226 $ 3,763 $ 223 $ 3,986 Ending valuation allowance $ (200 ) — $ (200 ) $ (314 ) — $ (314 ) Ending number of foreclosed assets 16 — 16 14 1 15 Proceeds from sale of foreclosed assets $ 2,656 $ 216 $ 2,872 $ 4,010 — $ 4,010 Gain on sale of foreclosed assets $ 718 $ (7 ) $ 711 $ 262 — $ 262

Premises and Equipment (Tables)

Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Summary of Premises and Equipment	Premises and equipment were comprised of: December 31, December 31, (In thousands) Land & land improvements $ 9,959 $ 9,522 Buildings 50,340 42,345 Furniture and equipment 35,939 31,428 96,238 83,295 Less: Accumulated depreciation (40,644 ) (37,412 ) 55,594 45,883 Construction in progress 2,148 2,523 Total premises and equipment $ 57,742 $ 48,406

Cash Value of Life Insurance (T

Cash Value of Life Insurance (Tables)	12 Months Ended
	Dec. 31, 2017
Investments, All Other Investments [Abstract]
Summary of Activity in Balance of Cash Value of Life Insurance	A summary of the activity in the balance of cash value of life insurance follows (dollars in thousands): Year ended December 31, 2017 2016 Beginning balance $ 95,912 $ 94,560 Increase in cash value of life insurance 2,685 2,717 Death benefit receivable in excess of cash value 108 238 Death benefit receivable (922 ) (1,603 ) Ending balance $ 97,783 $ 95,912 End of period death benefit $ 165,587 $ 165,669 Number of policies owned 182 185 Insurance companies used 14 14 Current and former employees and directors covered 57 58

Goodwill and Other Intangible47

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Goodwill Intangible	The following table summarizes the Company’s goodwill intangible as of the dates indicated: December 31, December 31, (Dollar in Thousands) 2017 Additions Reductions 2016 Goodwill $ 64,311 — — $ 64,311
Summary of Core Deposit Intangibles	The following table summarizes the Company’s core deposit intangibles as of the dates indicated: December 31, Reductions/ Fully December 31, (Dollar in Thousands) 2017 Additions Amortization Depreciated 2016 Core deposit intangibles $ 9,558 — — $ (562 ) $ 10,120 Accumulated amortization (4,384 ) — $ (1,389 ) $ 562 (3,557 ) Core deposit intangibles, net $ 5,174 — $ (1,389 ) — $ 6,563
Remaining Estimated Core Deposit Intangible Amortization	The following table summarizes the Company’s estimated core deposit intangible amortization (dollars in thousands): Estimated Core Deposit Years Ended Intangible Amortization 2018 $ 1,324 2019 1,228 2020 1,228 2021 969 2022 280 Thereafter 145

Mortgage Servicing Rights (Tabl

Mortgage Servicing Rights (Tables)	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Fair Value of Mortgage Servicing Rights	The following tables summarize the activity in, and the main assumptions we used to determine the fair value of mortgage servicing rights for the periods indicated (dollars in thousands): Years ended December 31, 2017 2016 2015 Balance at beginning of period $ 6,595 $ 7,618 $ 7,378 Acquisition — — — Originations 810 1,161 941 Change in fair value (718 ) (2,184 ) (701 ) Balance at end of period $ 6,687 $ 6,595 $ 7,618 Contractually specified servicing fees, late fees and ancillary fees earned $ 2,076 $ 2,065 $ 2,164 Balance of loans serviced at: Beginning of period $ 816,623 $ 817,917 $ 840,288 End of period $ 811,065 $ 816,623 $ 817,917 Weighted-average prepayment speed (CPR) 8.9 % 8.8 % 9.8 % Weighted-average discount rate 13.0 % 14.0 % 10.0 %

Indemnification Asset (Tables)

Indemnification Asset (Tables)	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Summary of Activity in Balance of Indemnification Asset (Liability)	A summary of the activity in the balance of indemnification asset (liability) included in other assets is follows (in thousands): Year ended December 31, 2017 2016 2015 Beginning balance $ (744 ) $ (521 ) $ (349 ) Effect of actual covered losses (recoveries) and increase (decrease) in estimated future covered losses (192 ) (412 ) (93 ) Change in estimated “true up” liability (32 ) (86 ) (71 ) Reimbursable expenses, net — 2 4 Payments made (received) 256 273 (12 ) Gain on termination of loss share agreement 712 — — Ending balance — $ (744 ) $ (521 ) Amount of indemnification asset (liability) recorded in other assets — $ (60 ) $ 77 Amount of indemnification liability recorded in other liabilities — (684 ) (598 ) Ending balance — $ (744 ) $ (521 )

Other Assets (Tables)

Other Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Summary of Other Assets	Other assets were comprised of (in thousands): As of December 31, 2017 2016 Deferred tax asset, net (Note 22) $ 21,697 $ 36,199 Prepaid expense 4,111 3,045 Software 1,126 2,039 Advanced compensation 16 249 Capital Trusts 1,706 1,702 Investment in Low Housing Tax Credit Funds 16,854 18,465 Life insurance proceeds receivable 2,242 2,120 Prepaid Taxes 4,754 6,460 Premises held for sale — 2,896 Miscellaneous other assets 2,545 1,568 Total other assets $ 55,051 $ 74,743

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2017
Banking and Thrift [Abstract]
Summary of Balances of Deposits	A summary of the balances of deposits follows (in thousands): December 31, 2017 2016 Noninterest-bearing demand $ 1,368,218 $ 1,275,745 Interest-bearing demand 971,459 887,625 Savings 1,364,518 1,397,036 Time certificates, over $250,000 73,596 75,184 Other time certificates 231,340 259,970 Total deposits $ 4,009,131 $ 3,895,560
Schedule of Maturities of Time Deposits	At December 31, 2017, the scheduled maturities of time deposits were as follows (in thousands): Scheduled Maturities 2018 2019 $ 250,277 2020 23,577 2021 17,699 2020 8,887 Thereafter 4,496 Total $ 304,936

Reserve for Unfunded Commitme52

Reserve for Unfunded Commitments (Tables)	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Summary of Activity in Reserve for Unfunded Commitments	The following tables summarize the activity in reserve for unfunded commitments for the periods indicated (dollars in thousands): Years ended December 31, 2017 2016 2015 Balance at beginning of period $ 2,719 $ 2,475 $ 2,145 Provision for losses – Unfunded commitments 445 244 330 Balance at end of period $ 3,164 $ 2,719 $ 2,475

Other Liabilities (Tables)

Other Liabilities (Tables)	12 Months Ended
	Dec. 31, 2017
Other Liabilities Disclosure [Abstract]
Components of Other Liabilities	Other liabilities were comprised of (in thousands): December 31, 2017 2016 Deferred compensation $ 6,605 $ 6,525 Pension liability 28,472 26,645 Joint beneficiary agreements 3,365 3,007 Low income housing tax credit fund commitments 8,554 15,176 Accrued salaries and benefits expense 6,619 5,704 Loan escrow and servicing payable 1,958 2,146 Deferred revenue 1,228 726 Litigation contingency 1,450 1,450 Miscellaneous other liabilities 5,007 5,985 Total other liabilities $ 63,258 $ 67,364

Other Borrowings (Tables)

Other Borrowings (Tables)	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Summary of Balances of Other Borrowings	A summary of the balances of other borrowings follows: December 31, 2017 2016 (in thousands) FHLB collateralized borrowing, fixed rate, as of December 31, 2017 of 1.38%, payable on January 2, 2018 $ 104,729 — Other collateralized borrowings, fixed rate, as of December 31, 2017 of 0.05%, payable on January 2, 2018 17,437 $ 17,493 Total other borrowings $ 122,166 $ 17,493

Junior Subordinated Debt (Table

Junior Subordinated Debt (Tables)	12 Months Ended
	Dec. 31, 2017
Text Block [Abstract]
Summary of Terms and Recorded Balance of Subordinated Debenture	The following table summarizes the terms and recorded balance of each subordinated debenture as of the date indicated (dollars in thousands): Coupon Rate As of December 31, 2017 Subordinated Maturity Face (Variable) Current Recorded Debt Series Date Value 3 mo. LIBOR + Coupon Rate Book Value TriCo Cap Trust I 10/7/2033 $20,619 3.05% 4.41% $ 20,619 TriCo Cap Trust II 7/23/2034 20,619 2.55% 3.91% 20,619 North Valley Trust II 4/24/2033 6,186 3.25% 4.63% 5,135 North Valley Trust III 4/24/2034 5,155 2.80% 4.16% 4,041 North Valley Trust IV 3/15/2036 10,310 1.33% 2.92% 6,444 $62,889 $ 56,858

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Future Minimum Commitments under Non-Cancelable Operating Leases with Initial or Remaining Terms of One Year or More	At December 31, 2017, future minimum commitments under non-cancelable Operating Leases (in thousands) 2018 $ 3,278 2019 2,499 2020 1,847 2021 1,488 2022 757 Thereafter 798 Future minimum lease payments $ 10,667
Summary of Bank's Commitments and Contingent Liabilities	The following table presents a summary of the Bank’s commitments and contingent liabilities: (in thousands) December 31, December 31, Financial instruments whose amounts represent risk: Commitments to extend credit: Commercial loans $ 257,220 $ 220,836 Consumer loans 422,958 406,855 Real estate mortgage loans 66,267 42,184 Real estate construction loans 187,097 97,399 Standby letters of credit 13,075 12,763 Deposit account overdraft privilege 98,260 98,583

Stock Options and Other Equit57

Stock Options and Other Equity-Based Incentive Instruments (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Option Activity	Stock option activity is summarized in the following table for the dates indicated: Number of Option Price per Share Weighted Outstanding at December 31, 2016 592,250 $ 12.63 to $ 23.21 $ 17.12 Options granted — — to — — Options exercised (145,850 ) $ 14.54 to $ 22.54 $ 17.97 Options forfeited — — to — — Outstanding at December 31, 2017 446,400 $ 12.63 to $ 23.21 $ 16.84
Summary of Options Outstanding	The following table shows the number, weighted-average exercise price, intrinsic value, and weighted average remaining contractual life of options exercisable, options not yet exercisable and total options outstanding as of December 31, 2017: Currently Currently Not Total Number of options 422,100 24,300 446,400 Weighted average exercise price $ 16.65 $ 20.21 $ 16.84 Intrinsic value (in thousands) $ 8,953 $ 429 $ 9,382 Weighted average remaining contractual term (yrs.) 3.8 5.7 3.9
Information about Options	The following table shows the total intrinsic value of options exercised, the total fair value of options vested, total compensation costs for options recognized in income, and total tax benefit recognized in income related to compensation costs for options during the periods indicated: Years Ended December 31, 2017 2016 2015 Intrinsic value of options exercised $ 2,657,000 $ 3,483,000 $ 969,000 Fair value of options that vested $ 259,000 $ 580,000 $ 734,000 Total compensation costs for options recognized in income $ 259,000 $ 580,000 $ 734,000 Total tax benefit recognized in income related to compensation costs for options $ 109,000 $ 244,000 $ 380,000 Excess tax benefit recognized in income $ 906,000 — —
Restricted Stock Unit (RSU) Activity	Restricted stock unit (RSU) activity is summarized in the following table for the dates indicated: Service Condition Vesting RSUs Market Plus Service Condition Vesting RSUs Number Weighted Number Weighted Outstanding at December 31, 2016 68,450 47,426 RSUs granted 29,669 $35.36 17,939 $32.95 Additional market plus service condition RSUs vested 6,269 RSUs added through dividend credits 1,245 — RSUs released (30,896 ) (18,805 ) RSUs forfeited/expired (11 ) — Outstanding at December 31, 2017 68,457 52,829
Summary of Compensation Costs for RSUs	The following table shows the compensation costs for RSUs recognized in income for the periods indicated: Year Ended December 31, 2017 2016 2015 Total compensation costs for RSUs recognized in income: Service condition vesting RSUs $ 895,000 $ 616,000 $ 458,000 Market plus service condition vesting RSUs $ 432,000 $ 271,000 $ 179,000

Noninterest Income and Expense

Noninterest Income and Expense (Tables)	12 Months Ended
	Dec. 31, 2017
Other Income and Expenses [Abstract]
Components of Other Noninterest Income	The components of other noninterest income were as follows (in thousands): Years Ended December 31, 2017 2016 2015 Service charges on deposit accounts $ 16,056 $ 14,365 $ 14,276 ATM and interchange fees 16,727 15,859 13,364 Other service fees 3,282 3,121 2,977 Mortgage banking service fees 2,076 2,065 2,164 Change in value of mortgage servicing rights (718 ) (2,184 ) (701 ) Total service charges and fees 37,423 33,226 32,080 Gain on sale of loans 3,109 4,037 3,064 Commissions on sale of non-deposit 2,729 2,329 3,349 Increase in cash value of life insurance 2,685 2,717 2,786 Gain on sale of investments 961 — — Lease brokerage income 782 711 712 Gain on sale of foreclosed assets 711 262 991 Change in indemnification asset 490 (493 ) (207 ) Sale of customer checks 372 408 492 Life insurance benefit in excess of cash value 108 238 155 Loss on disposal of fixed assets (142 ) (147 ) (129 ) Other 793 1,275 2,054 Total other noninterest income 12,598 11,337 13,267 Total noninterest income $ 50,021 $ 44,563 $ 45,347
Components of Noninterest Expense	The components of noninterest expense were as follows (in thousands): Years Ended December 31, 2017 2016 2015 Base salaries, net of deferred loan origination costs $ 54,589 $ 53,169 $ 46,822 Incentive compensation 9,227 8,872 6,964 Benefits and other compensation costs 19,114 18,683 17,619 Total salaries and benefits expense 82,930 80,724 71,405 Occupancy 10,894 10,139 10,126 Data processing and software 10,448 8,846 7,670 Equipment 7,141 6,597 5,997 ATM & POS network charges 4,752 4,999 4,190 Advertising 4,101 3,829 3,992 Professional fees 3,745 5,409 4,545 Telecommunications 2,713 2,749 3,007 Assessments 1,676 2,105 2,572 Operational losses 1,394 1,564 737 Intangible amortization 1,389 1,377 1,157 Postage 1,296 1,603 1,296 Courier service 1,035 998 1,154 Change in reserve for unfunded commitments 445 244 330 Foreclosed assets expense 231 266 490 Provision for foreclosed asset losses 162 140 502 Legal settlement — 1,450 — Merger & acquisition expense 530 784 586 Miscellaneous other 12,142 12,174 11,085 Total other noninterest expense 64,094 65,273 59,436 Total noninterest expense $ 147,024 $ 145,997 $ 130,841 Merger and acquisition expense: Base salaries, net of loan origination costs — $ 187 — Data processing and software — — $ 108 Professional fees $ 513 342 120 Other 17 255 358 Total merger expense $ 530 $ 784 $ 586

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Components of Consolidated Income Tax Expense	The components of consolidated income tax expense are as follows: 2017 2016 2015 (in thousands) Current tax expense Federal $ 17,835 $ 17,401 $ 21,076 State 6,650 7,121 7,139 $ 24,485 24,522 28,215 Deferred tax expense Federal 11,418 2,735 408 State 1,055 455 273 12,473 3,190 681 Total tax expense $ 36,958 $ 27,712 $ 28,896
Schedule of Components of Investments in Qualified Affordable Housing Projects	The Company recognized, as components of tax expense, tax credits and other tax benefits, and amortization expense relating to our investments in Qualified Affordable Housing Projects as followers for the periods indicated: Year ended December 31, 2017 2016 2015 (in thousands) Tax credits and other tax benefits – decrease in tax expense $ (1,753 ) $ (954 ) $ (354 ) Amortization – increase in tax expense $ 1,611 $ 757 $ 277
Reconciliation of Effective Tax Rate and Statutory Federal Income Tax Rate	The effective tax rate and the statutory federal income tax rate are reconciled as follows: Years Ended December 31, 2017 2016 2015 Federal statutory income tax rate 35.0 % 35.0 % 35.0 % State income taxes, net of federal tax benefit 6.9 6.8 6.6 Tax Cuts and Jobs Act impact on deferred re-measurement 9.6 — — Tax-exempt (1.9 ) (1.8 ) (0.7 ) Tax-exempt (1.3 ) (1.3 ) (1.3 ) Equity compensation (1.2 ) — — Low income housing tax credit benefits (2.3 ) (1.3 ) (0.4 ) Low income housing tax credit amortization 2.1 0.8 — Non-deductible 0.1 0.1 0.1 Non-deductible 0.2 — — Other 0.5 (0.1 ) 0.4 Effective Tax Rate 47.7 % 38.2 % 39.7 %
Company's Net Deferred Tax Asset Recorded in Other Assets	The temporary differences, tax effected, which give rise to the Company’s net deferred tax asset recorded in other assets are as follows as of December 31 for the years indicated: 2017 2016 (in thousands) Deferred tax assets: Allowance for losses and reserve for unfunded commitments $ 9,900 $ 14,809 Deferred compensation 1,953 2,743 Accrued pension liability 6,835 9,220 Accrued bonus 171 1,727 Other accrued expenses 522 781 Unfunded status of the supplemental retirement plans 1,582 1,982 State taxes 1,397 2,257 Share based compensation 1,322 2,063 Nonaccrual interest 282 408 OREO write downs 59 132 Indemnification asset — 313 Acquisition cost basis 2,187 3,996 Unrealized loss on securities 1,008 3,730 Tax credits 581 491 Net operating loss carryforwards 1,801 3,354 Other 508 981 Total deferred tax assets 30,108 48,987 Deferred tax liabilities: Securities income (958 ) (1,362 ) Depreciation (1,987 ) (3,032 ) Merger related fixed asset valuations (30 ) (54 ) Securities accretion (315 ) (478 ) Mortgage servicing rights valuation (1,943 ) (2,710 ) Core deposit intangible (916 ) (1,813 ) Junior subordinated debt (1,783 ) (2,616 ) Prepaid expenses and other (479 ) (723 ) Total deferred tax liability (8,411 ) (12,788 ) Net deferred tax asset $ 21,697 $ 36,199
Summary of Changes in Unrecognized Tax Benefit (Including Interest and Penalties)	A summary of changes in the Company’s unrecognized tax benefit (including interest and penalties) in 2017 is as follows: (in thousands) UTB Interest/Penalties Total As of December 31, 2016 $ 114 $ 7 $ 121 Lapse of the applicable statute of limitations (54 ) (5 ) (59 ) As of December 31, 2017 $ 60 $ 2 $ 62

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Computation of Earnings Per Share	Earnings per share have been computed based on the following: Years ended December 31, 2017 2016 2015 Net income (in thousands) $ 40,554 $ 44,811 $ 43,818 (number of shares in thousands) Average number of common shares outstanding 22,912 22,814 22,750 Effect of dilutive stock options 338 273 248 Average number of common shares outstanding used to calculate diluted earnings per share 23,250 23,087 22,998

Comprehensive Income (Tables)

Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Components of Other Comprehensive Income and Related Tax Effects	The components of other comprehensive income and related tax effects are as follows: Years Ended December 31, 2017 2016 2015 (in thousands) Unrealized holding losses on available for sale securities before reclassifications $ 6,422 $ (11,015 ) $ (1,895 ) Amounts reclassified out of accumulated other comprehensive income (961 ) — — Unrealized holding losses on available for sale securities after reclassifications 5,461 (11,015 ) (1,895 ) Tax effect (2,296 ) 4,631 797 Unrealized holding losses on available for sale securities, net of tax 3,165 (6,384 ) (1,098 ) Change in unfunded status of the supplemental retirement plans before reclassifications (1,016 ) 511 1,384 Amounts reclassified out of accumulated other comprehensive income: Amortization of prior service cost (12 ) (40 ) (57 ) Amortization of actuarial losses 390 550 823 Total amounts reclassified out of accumulated other comprehensive income 378 510 766 Change in unfunded status of the supplemental retirement plans after reclassifications (638 ) 1,021 2,150 Tax effect 268 (429 ) (904 ) Change in unfunded status of the supplemental retirement plans, net of tax (370 ) 592 1,246 Change in joint beneficiary agreement liability before reclassifications (110 ) (343 ) 277 Amounts reclassified out of accumulated other comprehensive income — — — Change in joint beneficiary agreement liability after reclassifications (110 ) (343 ) 277 Tax effect — — — Change in joint beneficiary agreement liability, net of tax (110 ) (343 ) 277 Total other comprehensive income (loss) $ 2,685 $ (6,135 ) $ 425
Components of Accumulated Other Comprehensive Income	The components of accumulated other comprehensive income, included in shareholders’ equity, are as follows: December 31, 2017 2016 (in thousands) Net unrealized gains on available for sale securities $ (3,409 ) $ (8,870 ) Tax effect 1,008 3,729 Unrealized holding gains on available for sale securities, net of tax (2,401 ) (5,141 ) Unfunded status of the supplemental retirement plans (5,352 ) (4,714 ) Tax effect 2,250 1,982 Unfunded status of the supplemental retirement plans, net of tax (3,102 ) (2,732 ) Joint beneficiary agreement liability (150 ) (40 ) Tax effect — — Joint beneficiary agreement liability, net of tax (150 ) (40 ) Accumulated other comprehensive loss $ (5,228 ) $ (7,913 )

Retirement Plans (Tables)

Retirement Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Defined Benefit Pension Plans	Amounts recognized as a component of accumulated other comprehensive loss as of year-end December 31, (in thousands) 2017 2016 Transition obligation $ 4 $ 7 Prior service cost (248 ) (75 ) Net actuarial loss 5,596 4,782 Amount included in accumulated other comprehensive loss 5,352 4,714 Deferred tax benefit (2,250 ) (1,982 ) Amount included in accumulated other comprehensive loss, net of tax $ 3,102 $ 2,732
Information Pertaining to Activity in Supplemental Retirement Plans	Information pertaining to the activity in the supplemental retirement plans, using a measurement date of December 31, is as follows: December 31, 2017 2016 (in thousands) Change in benefit obligation: Benefit obligation at beginning of year $ (26,645 ) $ (26,184 ) Acquisition — — Service cost (941 ) (1,042 ) Interest cost (991 ) (1,025 ) Actuarial (loss)/gain (1,203 ) 511 Plan amendments 185 — Benefits paid 1,123 1,095 Benefit obligation at end of year $ (28,472 ) $ (26,645 ) Change in plan assets: Fair value of plan assets at beginning of year $ — $ — Fair value of plan assets at end of year $ — $ — Funded status $ (28,472 ) $ (26,645 ) Unrecognized net obligation existing at January 1, 1986 4 7 Unrecognized net actuarial loss 5,596 4,782 Unrecognized prior service cost (248 ) (75 ) Accumulated other comprehensive income (5,352 ) (4,714 ) Accrued benefit cost $ (28,472 ) $ (26,645 ) Accumulated benefit obligation $ (26,432 ) $ (25,241 )
Net Periodic Benefit Cost Recognized for Supplemental Retirement Plans	The following table sets forth the net periodic benefit cost recognized for the supplemental retirement plans: Years Ended December 31, 2017 2016 2015 (in thousands) Net pension cost included the following components: Service cost-benefits earned during the period $ 941 $ 1,042 $ 1,023 Interest cost on projected benefit obligation 991 1,025 957 Amortization of net obligation at transition 2 2 2 Amortization of prior service cost (12 ) (41 ) (57 ) Recognized net actuarial loss 390 549 823 Net periodic pension cost $ 2,312 $ 2,577 $ 2,748
Assumptions Used in Accounting for Plans	The following table sets forth assumptions used in accounting for the plans: Years Ended December 31, 2017 2016 2015 Discount rate used to calculate benefit obligation 3.40 % 3.80 % 4.00 % Discount rate used to calculate net periodic pension cost 3.84 % 4.00 % 3.65 % Average annual increase in executive compensation 3.25 % 2.50 % 2.50 % Average annual increase in director compensation 0.00 % 2.50 % 2.50 %
Expected Benefit Payments to Participants and Estimated Contributions to be Made by Company	The following table sets forth the expected benefit payments to participants and estimated contributions to be made by the Company under the supplemental retirement plans for the years indicated: Years Ended Expected Benefit Estimated (in thousands) 2018 $ 1,106 $ 1,106 2019 1,067 1,067 2020 1,233 1,233 2021 1,859 1,859 2022 2,008 2,008 2023-2027 $ 10,169 $ 10,169

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Summary of Activity in Lending Transactions	The following table summarizes the activity in these loans for the periods indicated (in thousands): Balance December 31, 2015 $ 4,201 Advances/new loans 730 Removed/payments (2,499 ) Balance December 31, 2016 $ 2,432 Advances/new loans 437 Removed/payments (721 ) Balance December 31, 2017 $ 2,148

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Recorded Amount of Assets and Liabilities Measured at Fair Value on Recurring Basis	The table below presents the recorded amount of assets and liabilities measured at fair value on a recurring basis (in thousands): Total Level 1 Level 2 Level 3 Fair value at December 31, 2017 Securities available-for-sale: Obligations of U.S. government corporations and agencies $ 604,789 — $ 604,789 — Obligations of states and political subdivisions 123,156 — 123,156 — Marketable equity securities 2,938 $ 2,938 — — Mortgage servicing rights 6,687 — — $ 6,687 Total assets measured at fair value $ 737,570 $ 2,938 $ 727,945 $ 6,687 Total Level 1 Level 2 Level 3 Fair value at December 31, 2016 Securities available-for-sale: Obligations of U.S. government corporations and agencies $ 429,678 — $ 429,678 — Obligations of states and political subdivisions 117,617 — 117,617 — Marketable equity securities 2,938 $ 2,938 — — Mortgage servicing rights 6,595 — — $ 6,595 Total assets measured at fair value $ 556,828 $ 2,938 $ 547,295 $ 6,595
Reconciliation of Assets and Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3) on Recurring Basis	The following table provides a reconciliation of assets and liabilities measured at fair value using significant unobservable inputs (Level 3) on a recurring basis during the years ended December 31, 2017, 2016, and 2015. Had there been any transfer into or out of Level 3 during 2017, 2016, or 2015, the amount included in the “Transfers into (out of) Level 3” column would represent the beginning balance of an item in the period (interim quarter) during which it was transferred (in thousands): Ending Transfers Change Issuances Beginning Year ended December 31, 2017: Mortgage servicing rights $ 6,687 — $ (718 ) $ 810 $ 6,595 2016: Mortgage servicing rights $ 6,595 — $ (2,184 ) $ 1,161 $ 7,618 2015: Mortgage servicing rights $ 7,618 — $ (701 ) $ 941 $ 7,378
Quantitative Information about Recurring Level 3 Fair Value Measurements	The following table presents quantitative information about recurring Level 3 fair value measurements at December 31, 2017 and 2016: Fair Value Valuation Unobservable Range, December 31, 2017 Mortgage Servicing Rights $ 6,687 Discounted cash flow Constant prepayment rate 6.2%-22.0%, 8.9% Discount rate 13.0%-15.0%, 13.0% December 31, 2016 Mortgage Servicing Rights $ 6,595 Discounted cash flow Constant prepayment rate 6.9%-16.6%, 8.8% Discount rate 14.0%-16.0%, 14.0%
Assets and Liabilities Measured at Fair Value on Nonrecurring Basis	The tables below present the recorded amount of assets and liabilities measured at fair value on a nonrecurring basis, as of the dates indicated, that had a write-down or an additional allowance provided during the periods indicated (in thousands): Total Level 1 Level 2 Level 3 Total Gains Year ended December 31, 2017 Fair value: Impaired Originated & PNCI loans $ 2,767 — — $ 2,767 $ (1,452 ) Foreclosed assets 2,217 2,217 (135 ) Total assets measured at fair value $ 4,984 — — $ 4,984 $ (1,587 ) Total Level 1 Level 2 Level 3 Total Gains Year ended December 31, 2016 Fair value: Impaired Originated & PNCI loans $ 1,107 — — $ 1,107 $ (409 ) Foreclosed assets 2,253 2,253 (86 ) Total assets measured at fair value $ 3,360 — — $ 3,360 $ (495 )
Quantitative Information about Level 3 Fair Value Measurements for Financial Instruments Measured at Fair Value on Nonrecurring Basis	The following table presents quantitative information about Level 3 fair value measurements for financial instruments measured at fair value on a nonrecurring basis at December 31, 2017 and 2016: December 31, 2017 Fair Value Valuation Technique Unobservable Inputs Range, Impaired Originated & PNCI loans $ 2,767 Sales comparison approach Income approach Adjustment for differences between comparable sales Capitalization rate Not meaningful N/A Foreclosed assets (Land & construction) $ 1,341 Sales comparison approach Adjustment for differences between comparable sales Not meaningful Foreclosed assets (residential (Residential real estate) $ 622 Sales comparison approach Adjustment for differences between comparable sales Not meaningful Foreclosed assets (Commercial real estate) $ 254 Sales comparison approach Adjustment for differences between comparable sales Not meaningful December 31, 2016 Fair Value Valuation Technique Unobservable Inputs Range, Impaired Originated & PNCI loans $ 1,107 Sales comparison approach Income approach Adjustment for differences between comparable sales Capitalization rate Not meaningful N/A Foreclosed assets (Land & construction) $ 15 Sales comparison approach Adjustment for differences between comparable sales Not meaningful Foreclosed assets (residential (Residential real estate) $ 1,564 Sales comparison approach Adjustment for differences between comparable sales Not meaningful Foreclosed assets (Commercial real estate) $ 674 Sales comparison approach Adjustment for differences between comparable sales Not meaningful
Estimated Fair Values of Financial Instruments that are Reported at Amortized Cost in Consolidated Balance Sheets	The estimated fair values of financial instruments that are reported at amortized cost in the Corporation’s consolidated balance sheets, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value, were as follows (in thousands): December 31, 2017 December 31, 2016 Carrying Fair Carrying Fair Financial assets: Level 1 inputs: Cash and due from banks $ 105,968 $ 105,968 $ 92,197 $ 92,197 Cash at Federal Reserve and other banks 99,460 99,460 213,415 213,415 Level 2 inputs: Securities held to maturity 514,844 518,165 602,536 603,203 Restricted equity securities 16,956 N/A 16,596 N/A Loans held for sale 4,616 4,616 2,998 2,998 Level 3 inputs: Loans, net 2,984,842 2,992,225 2,727,090 2,763,473 Financial liabilities: Level 2 inputs: Deposits 4,009,131 4,006,620 3,895,560 3,893,941 Other borrowings 122,166 122,166 17,493 17,493 Level 3 inputs: Junior subordinated debt $ 56,858 $ 58,466 $ 56,667 $ 49,033 Contract Fair Contract Fair Off-balance Level 3 inputs: Commitments $ 933,542 $ 9,335 $ 767,274 $ 7,673 Standby letters of credit $ 13,075 $ 131 $ 12,763 $ 128 Overdraft privilege commitments $ 98,260 $ 983 $ 98,583 $ 986

TriCo Bancshares Condensed Fi65

TriCo Bancshares Condensed Financial Statements (Parent Only) (Tables)	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Balance Sheets	Condensed Balance Sheets December 31, 2017 2016 (in thousands) Assets Cash and Cash equivalents $ 3,924 $ 2,802 Investment in Tri Counties Bank 557,538 529,907 Other assets 1,721 1,711 Total assets $ 563,183 $ 534,420 Liabilities and shareholders’ equity Other liabilities $ 517 $ 406 Junior subordinated debt 56,858 56,667 Total liabilities 57,375 57,073 Shareholders’ equity: Common stock, no par value: authorized 50,000,000 shares; issued and outstanding 22,955,963 and 22,867,802 shares, respectively 255,836 252,820 Retained earnings 255,200 232,440 Accumulated other comprehensive loss, net (5,228 ) (7,913 ) Total shareholders’ equity 505,808 477,347 Total liabilities and shareholders’ equity $ 563,183 $ 534,420
Statements of Income	Condensed Statements of Income Years ended December 31, 2017 2016 2015 (in thousands) Interest expense $ (2,535 ) $ (2,229 ) $ (1,977 ) Administration expense (915 ) (725 ) (814 ) Loss before equity in net income of Tri Counties Bank (3,450 ) (2,954 ) (2,791 ) Equity in net income of Tri Counties Bank: Distributed 19,236 16,758 13,304 Undistributed 23,359 29,764 32,131 Income tax benefit 1,409 1,243 1,174 Net income $ 40,554 $ 44,811 $ 43,818
Statements of Comprehensive Income	Condensed Statements of Comprehensive Income Years ended December 31, 2017 2016 2015 (in thousands) Net income $ 40,554 $ 44,811 $ 43,818 Other comprehensive income (loss), net of tax: Unrealized holding gains (losses) on securities arising during the period 3,165 (6,384 ) (1,098 ) Change in minimum pension liability (370 ) 592 1,246 Change in joint beneficiary agreement liability (110 ) (343 ) 277 Other comprehensive income (loss) 2,685 (6,135 ) 425 Comprehensive income $ 43,239 $ 38,676 $ 44,243
Statements of Cash Flows	Condensed Statements of Cash Flows Years ended December 31, 2017 2016 2015 (in thousands) Operating activities: Net income $ 40,554 $ 44,811 $ 43,818 Adjustments to reconcile net income to net cash provided by operating activities: Undistributed equity in earnings of Tri Counties Bank (23,359 ) (29,764 ) (32,131 ) Equity compensation vesting expense 1,586 1,467 1,370 Equity compensation tax effect — (155 ) 68 Net change in other assets and liabilities (1,295 ) (1,210 ) (1,120 ) Net cash provided by operating activities 17,486 15,149 12,005 Investing activities: None Financing activities: Issuance of common stock through option exercise 396 518 660 Equity compensation tax effect — 155 (68 ) Repurchase of common stock (1,629 ) (1,890 ) (412 ) Cash dividends paid — common (15,131 ) (13,695 ) (11,849 ) Net cash used for financing activities (16,364 ) (14,912 ) (11,669 ) Increase in cash and cash equivalents 1,122 237 336 Cash and cash equivalents at beginning of year 2,802 2,565 2,229 Cash and cash equivalents at end of year $ 3,924 $ 2,802 $ 2,565

Regulatory Matters (Tables)

Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2017
Banking and Thrift [Abstract]
Actual and Required Capital Ratios of Bank	The following tables present actual and required capital ratios as of December 31, 2017 and 2016 for the Company and the Bank under Basel III Capital Rules. The minimum capital amounts presented include the minimum required capital levels as of December 31, 2017 and 2016 based on the phased-in phased-in. Actual Minimum Capital Phase-in Minimum Capital Required to be Amount Ratio Amount Ratio Amount Ratio Amount Ratio (dollars in thousands) As of December 31, 2017: Total Capital (to Risk Weighted Assets): Consolidated $ 528,805 14.07 % $ 347,694 9.250 % $ 394,679 10.50 % N/A N/A Tri Counties Bank $ 525,384 13.98 % $ 347,535 9.250 % $ 394,499 10.50 % $ 375,713 10.00 % Tier 1 Capital (to Risk Weighted Assets): Consolidated $ 495,318 13.18 % $ 272,517 7.250 % $ 319,502 8.50 % N/A N/A Tri Counties Bank $ 491,897 13.09 % $ 272,392 7.250 % $ 319,356 8.50 % $ 300,570 8.00 % Common equity Tier 1 Capital (to Risk Weighted Assets): Consolidated $ 440,643 11.72 % $ 216,134 5.750 % $ 263,120 7.00 % N/A N/A Tri Counties Bank $ 491,897 13.09 % $ 216,035 5.750 % $ 262,999 7.00 % $ 244,214 6.50 % Tier 1 Capital (to Average Assets): Consolidated $ 495,318 10.80 % $ 183,400 4.000 % $ 183,400 4.00 % N/A N/A Tri Counties Bank $ 491,897 10.73 % $ 183,394 4.000 % $ 183,394 4.00 % $ 229,243 5.00 % As of December 31, 2016: Total Capital (to Risk Weighted Assets): Consolidated $ 503,283 14.77 % $ 293,854 8.625 % $ 357,735 10.50 % N/A N/A Tri Counties Bank $ 500,876 14.71 % $ 293,706 8.625 % $ 357,556 10.50 % $ 340,529 10.00 % Tier 1 Capital (to Risk Weighted Assets): Consolidated $ 468,061 13.74 % $ 225,714 6.625 % $ 289,595 8.50 % N/A N/A Tri Counties Bank $ 465,654 13.67 % $ 225,601 6.625 % $ 289,450 8.50 % $ 274,725 8.00 % Common equity Tier 1 Capital (to Risk Weighted Assets): Consolidated $ 414,632 12.17 % $ 174,609 5.125 % $ 238,490 7.00 % N/A N/A Tri Counties Bank $ 465,654 13.66 % $ 174,521 5.125 % $ 238,370 7.00 % $ 221,344 6.50 % Tier 1 Capital (to Average Assets): Consolidated $ 468,061 10.62 % $ 176,346 4.000 % $ 176,346 4.00 % N/A N/A Tri Counties Bank $ 465,654 10.56 % $ 176,341 4.000 % $ 176,341 4.00 % $ 220,426 5.00 %

Summary of Quarterly Results 67

Summary of Quarterly Results of Operations (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Results of Operations	The following table sets forth the results of operations for the four quarters of 2017 and 2016, and is unaudited; however, in the opinion of Management, it reflects all adjustments (which include only normal recurring adjustments) necessary to present fairly the summarized results for such periods. 2017 Quarters Ended December 31, September 30, June 30, March 31, (dollars in thousands, except per share data) Interest and dividend income: Loans: Discount accretion PCI – cash basis $ 516 $ 398 $ 386 $ 112 Discount accretion PCI – other 445 407 797 631 Discount accretion PNCI 528 559 987 798 All other loan interest income 36,705 35,904 34,248 33,373 Total loan interest income 38,194 37,268 36,418 34,914 Debt securities, dividends and interest bearing cash at Banks (not FTE) 8,767 8,645 8,626 8,570 Total interest income 46,961 45,913 45,044 43,484 Interest expense 1,868 1,829 1,610 1,491 Net interest income 45,093 44,084 43,434 41,993 Provision for (benefit from reversal of provision for) loan losses 1,677 765 (796 ) (1,557 ) Net interest income after provision for loan losses 43,416 43,319 44,230 43,550 Noninterest income 12,478 12,930 12,910 11,703 Noninterest expense 38,076 37,222 35,904 35,822 Income before income taxes 17,818 19,027 21,236 19,431 Income tax expense 14,829 7,130 7,647 7,352 Net income $ 2,989 $ 11,897 $ 13,589 $ 12,079 Per common share: Net income (diluted) $ 0.13 $ 0.51 $ 0.58 $ 0.52 Dividends $ 0.17 $ 0.17 $ 0.17 $ 0.15 2016 Quarters Ended December 31, September 30, June 30, March 31, (dollars in thousands, except per share data) Interest and dividend income: Loans: Discount accretion PCI – cash basis $ 483 $ 777 $ 426 $ 269 Discount accretion PCI – other 658 569 415 (45 ) Discount accretion PNCI 637 883 1,459 868 All other loan interest income 34,463 33,540 32,038 33,646 Total loan interest income 36,241 35,769 34,338 34,738 Debt securities, dividends and interest bearing cash at Banks (not FTE) 8,374 7,940 8,252 8,056 Total interest income 44,615 43,709 42,590 42,794 Interest expense 1,460 1,439 1,430 1,392 Net interest income 43,155 42,270 41,160 41,402 (Benefit from reversal of) provision for loan losses (1,433 ) (3,973 ) (773 ) 209 Net interest income after provision for loan losses 44,588 46,243 41,933 41,193 Noninterest income 12,462 11,066 11,245 9,790 Noninterest expense 36,563 37,416 38,267 33,751 Income before income taxes 20,487 19,893 14,911 17,232 Income tax expense 7,954 7,694 5,506 6,558 Net income $ 12,533 $ 12,199 $ 9,405 $ 10,674 Per common share: Net income (diluted) $ 0.54 $ 0.53 $ 0.41 $ 0.46 Dividends $ 0.15 $ 0.15 $ 0.15 $ 0.15

Summary of Significant Accoun68

Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended	12 Months Ended
	Sep. 30, 2017USD ($)	Dec. 31, 2018	Dec. 31, 2017USD ($)OfficeSegmentLocationTrustBranchBusiness	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Jan. 01, 2018USD ($)
Significant Of Accounting Policies [Line Items]
Number of subsidiary business trusts | Trust			5
Number of loan production offices | Office			2
Company's investments in the trusts			$ 1,721,000
Number of business segment | Segment			1
Trading securities			$ 0	$ 0
Sale of classified investment securities			24,796,000	0
Proceeds from sale of investment securities			25,757,000
Gain from sale of classified investment securities			961,000		$ 0
Recognized OTTI losses			$ 0	0
Loans contractual past due			90 days
TDR loans payment period in nonaccrual status			6 months
Recognition of excess tax benefits			$ 109,000	$ 244,000	$ 380,000
Federal statutory income tax rate			35.00%	35.00%	35.00%
Scenario, Forecast [Member]
Significant Of Accounting Policies [Line Items]
Federal statutory income tax rate		21.00%
Tri Counties Bank [Member]
Significant Of Accounting Policies [Line Items]
Number of locations acquired | Location			3
Number of traditional operating branches | Branch			57
Number of in-store operating branches | Branch			9
California [Member]
Significant Of Accounting Policies [Line Items]
Number of counties | Business			26
ASU 2016-09 [Member]
Significant Of Accounting Policies [Line Items]
Recognition of excess tax benefits			$ 906,000
ASU 2018-02 [Member] | Subsequent Event [Member] | Retained Earnings [Member]
Significant Of Accounting Policies [Line Items]
Cumulative-effect adjustment to balance sheet						$ 1,093,000
ASU 2018-02 [Member] | Subsequent Event [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Significant Of Accounting Policies [Line Items]
Cumulative-effect adjustment to balance sheet						$ (1,093,000)
Reclassifications [Member] | Mortgage Loans on Real Estate [Member] | Residential 1-4 Family [Member]
Significant Of Accounting Policies [Line Items]
Loans	$ 60,957,000
Reclassifications [Member] | Consumer [Member] | Home Equity Loans [Member]
Significant Of Accounting Policies [Line Items]
Loans	$ 5,620,000
Minimum [Member] | Parent [Member] | Reclassifications [Member]
Significant Of Accounting Policies [Line Items]
Total risk based capital ratios, increase percentage	0.10%
Tier 1 capital ratios, increase percentage	0.10%
Tier 1 common equity ratios, increase percentage	0.10%
Minimum [Member] | Tri Countries Bank [Member] | Reclassifications [Member]
Significant Of Accounting Policies [Line Items]
Total risk based capital ratios, increase percentage	0.10%
Tier 1 capital ratios, increase percentage	0.10%
Tier 1 common equity ratios, increase percentage	0.10%
Maximum [Member] | Parent [Member] | Reclassifications [Member]
Significant Of Accounting Policies [Line Items]
Total risk based capital ratios, increase percentage	0.20%
Tier 1 capital ratios, increase percentage	0.20%
Tier 1 common equity ratios, increase percentage	0.20%
Maximum [Member] | Tri Countries Bank [Member] | Reclassifications [Member]
Significant Of Accounting Policies [Line Items]
Total risk based capital ratios, increase percentage	0.20%
Tier 1 capital ratios, increase percentage	0.20%
Tier 1 common equity ratios, increase percentage	0.20%
Furniture and Equipment [Member] | Minimum [Member]
Significant Of Accounting Policies [Line Items]
Estimated useful lives of the related assets or lease terms			3 years
Furniture and Equipment [Member] | Maximum [Member]
Significant Of Accounting Policies [Line Items]
Estimated useful lives of the related assets or lease terms			10 years
Land Improvements and Buildings [Member] | Minimum [Member]
Significant Of Accounting Policies [Line Items]
Estimated useful lives of the related assets or lease terms			15 years
Land Improvements and Buildings [Member] | Maximum [Member]
Significant Of Accounting Policies [Line Items]
Estimated useful lives of the related assets or lease terms			40 years

Business Combinations - Additio

Business Combinations - Additional Information (Detail)	Dec. 11, 2017USD ($)$ / shares	Dec. 08, 2017USD ($)$ / shares	Mar. 18, 2016USD ($)Branches	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Business Acquisition [Line Items]
Common stock, closing price | $ / shares		$ 41.64
Goodwill recognized				$ 64,311,000	$ 64,311,000
Merger Agreement [Member] | FNBB [Member]
Business Acquisition [Line Items]
Ownership percentage of combined entity post merger		24.00%
Bank of America [Member]
Business Acquisition [Line Items]
Total consideration value			$ 3,204,000
Number of branches | Branches			3
Acquisition, completion date			Oct. 28, 2015
Cash consideration			$ 3,204,000
Deposits			161,231,000
Loans			289,000
Cash			159,520,000
Goodwill recognized			849,000
Increase in net book value of land and buildings acquired			309,000
Recognized intangible related to acquisition			2,046,000
Bank of America [Member] | Core Deposit Intangibles [Member]
Business Acquisition [Line Items]
Recognized intangible related to acquisition			$ 2,046,000
Percentage of acquired intangibles			1.50%
Finite lived intangible asset estimated useful life			7 years
FNBB [Member]
Business Acquisition [Line Items]
Consideration value, per share | $ / shares		$ 40.81
Total consideration value		$ 315,300,000
FNBB [Member] | Merger Agreement [Member]
Business Acquisition [Line Items]
Average share price of the Company's Stock, percentage	120.00%
Initial price | $ / shares	$ 41.48
Merger Agreement termination conditions	(i) the average share price of the Company’s common stock for the 20 day period up to and including the fifth day prior to the closing date (the “Average Closing Share Price”) is greater than $49.78, which equals 120% of the average share price of the Company’s Stock for the 20 trading-day period up to and including December 8, 2017, which was $41.48 (the “Initial Price”) and (ii) the Company’s common stock outperforms the KBW Regional Banking Index by more than 20%, unless FNBB agrees that the Exchange Ratio will be reduced and fewer shares of the Company’s common stock will be issued to FNBB shareholders on a per share basis. Conversely, FNBB can terminate the Merger Agreement if both (i) the Average Closing Share Price is less than $33.18, which is equivalent to 80% of the Initial Price, and (ii) the Company’s common stock underperforms the KBW Regional Banking Index by more than 20%, unless the Company agrees that the Exchange Ratio will be increased and more shares of the Company common stock will be issued to FNBB shareholders on a per share basis.
Percentage of initial price	80.00%
FNBB [Member] | Merger Agreement [Member] | KBW Regional Banking Index [Member]
Business Acquisition [Line Items]
Percentage of common stock outperforms in excess of KBW Regional Banking Index	20.00%
FNBB [Member] | Merger Agreement [Member] | Minimum [Member]
Business Acquisition [Line Items]
Consideration value, per share | $ / shares	$ 49.78
FNBB [Member] | Merger Agreement [Member] | Maximum [Member]
Business Acquisition [Line Items]
Consideration value, per share | $ / shares	$ 33.18
Number of trading days	20 days
Shares held by acquiree	$ 119,000,000
FNBB [Member] | Common Stock [Member]
Business Acquisition [Line Items]
Shares exchange ratio	0.98

Business Combinations - Schedul

Business Combinations - Schedule of Fair Value of Consideration Transferred, Identifiable Net Assets Acquired and Resulting Goodwill (Detail) - USD ($) $ in Thousands	Mar. 18, 2016	Dec. 31, 2017	Dec. 31, 2016
Liabilities assumed:
Goodwill recognized		$ 64,311	$ 64,311
Bank of America [Member]
Fair value of consideration transferred:
Cash consideration	$ 3,204
Total fair value of consideration transferred	3,204
Asset acquired:
Cash and cash equivalents	159,520
Loans	289
Premises and equipment	1,590
Core deposit intangible	2,046
Other assets	141
Total assets acquired	163,586
Liabilities assumed:
Deposits	161,231
Total liabilities assumed	161,231
Total net assets acquired	2,355
Goodwill recognized	$ 849

Business Combinations - Summary

Business Combinations - Summary of Cash Paid and Estimated Fair Value Adjustments Resulting in Goodwill (Detail) - USD ($) $ in Thousands	Mar. 18, 2016	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill		$ 64,311	$ 64,311
Bank of America [Member]
Business Acquisition [Line Items]
Cash paid	$ 3,204
Cost basis net assets acquired	0
Fair Value Adjustments, Premises and Equipment	(309)
Core deposit intangible	(2,046)
Goodwill	849
Bank of America [Member] | Loans [Member]
Business Acquisition [Line Items]
Fair Value Adjustments	$ 0

Investment Securities - Amortiz

Investment Securities - Amortized Cost and Estimated Fair Values of Investments in Debt and Equity Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 734,292	$ 559,103
Gross Unrealized Gains	2,583	2,216
Gross Unrealized Losses	(5,992)	(11,086)
Estimated Fair Value	730,883	550,233
Amortized Cost, Held to Maturity	514,844	602,536
Gross Unrealized Gains, Held to Maturity	5,247	5,057
Gross Unrealized Losses, Held to Maturity	(1,926)	(4,390)
Estimated Fair Value, Held to Maturity	518,165	603,203
Obligations of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	609,695	434,357
Gross Unrealized Gains	695	1,949
Gross Unrealized Losses	(5,601)	(6,628)
Estimated Fair Value	604,789	429,678
Amortized Cost, Held to Maturity	500,271	587,982
Gross Unrealized Gains, Held to Maturity	5,101	5,001
Gross Unrealized Losses, Held to Maturity	(1,889)	(4,199)
Estimated Fair Value, Held to Maturity	503,483	588,784
Obligations of States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	121,597	121,746
Gross Unrealized Gains	1,888	267
Gross Unrealized Losses	(329)	(4,396)
Estimated Fair Value	123,156	117,617
Amortized Cost, Held to Maturity	14,573	14,554
Gross Unrealized Gains, Held to Maturity	146	56
Gross Unrealized Losses, Held to Maturity	(37)	(191)
Estimated Fair Value, Held to Maturity	14,682	14,419
Marketable Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,000	3,000
Gross Unrealized Losses	(62)	(62)
Estimated Fair Value	$ 2,938	$ 2,938

Investment Securities - Additio

Investment Securities - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017USD ($)Investmentsecurities	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Investment Securities [Line Items]
Investment securities sold			$ 2,000
Sale of classified investment securities	$ 24,796,000	$ 0
Investment securities carrying value	285,596,000	$ 292,737,000
Investment securities cost basis	25,757,000
Gain or loss on sale of investment securities	961,000		$ 0
Residential real estate mortgage-backed securities	$ 1,109,966,000
Life of mortgage-backed securities	5 years 10 months 25 days
Obligations of U.S. Government Corporations and Agencies [Member]
Investment Securities [Line Items]
Debt securities | Investmentsecurities	69
Percentage of aggregate depreciation in unrealized losses	1.16%
Obligations of States and Political Subdivisions [Member]
Investment Securities [Line Items]
Debt securities | Investmentsecurities	29
Percentage of aggregate depreciation in unrealized losses	1.38%
Marketable Equity Securities [Member]
Investment Securities [Line Items]
Percentage of aggregate depreciation in unrealized losses	2.07%

Investment Securities - Amort74

Investment Securities - Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Due in one year, Amortized Cost	$ 2
Due after one year through five years, Amortized Cost	211
Due after five years through ten years, Amortized Cost	2,231
Due after ten years, Amortized Cost	731,848
Totals, Amortized Cost	734,292
Due in one year, Estimated Fair Value	2
Due after one year through five years, Estimated Fair Value	211
Due after five years through ten years, Estimated Fair Value	2,281
Due after ten years, Estimated Fair Value	728,389
Totals, Estimated Fair Value	730,883
Due in one year, Amortized Cost, Held to Maturity	0
Due after one year through five years, Amortized Cost, Held to Maturity	1,207
Due after five years through ten years, Amortized Cost, Held to Maturity	14,011
Due after ten years, Amortized Cost, Held to Maturity	499,626
Totals, Amortized Cost, Held to Maturity	514,844	$ 602,536
Due in one year, Estimated Fair Value, Held to Maturity	0
Due after one year through five years, Estimated Fair Value, Held to Maturity	1,226
Due after five years through ten years, Estimated Fair Value, Held to Maturity	14,067
Due after ten years, Estimated Fair Value, Held to Maturity	502,872
Estimated Fair Value, Held to Maturity	$ 518,165	$ 603,203

Investment Securities - Gross U

Investment Securities - Gross Unrealized Losses on Investment (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	$ 289,271	$ 464,152
Less than 12 months, Unrealized Loss	(2,211)	(11,086)
12 months or more, Fair Value	186,361
12 months or more, Unrealized Loss	(3,781)
Total Fair Value	475,632	464,152
Total Unrealized Loss	(5,992)	(11,086)
Less than 12 months, Fair Value, held to maturity	94,505	290,481
Less than 12 months, Unrealized Loss, held to maturity	(574)	(4,390)
12 months or more, Fair Value, held to maturity	98,004
12 months or more, Unrealized Loss, held to maturity	(1,352)
Total Fair Value, held to maturity	192,509	290,481
Total Unrealized Loss, held to maturity	(1,926)	(4,390)
Obligations of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	284,367	370,389
Less than 12 months, Unrealized Loss	(2,176)	(6,628)
12 months or more, Fair Value	166,338
12 months or more, Unrealized Loss	(3,425)
Total Fair Value	450,705	370,389
Total Unrealized Loss	(5,601)	(6,628)
Less than 12 months, Fair Value, held to maturity	93,017	280,497
Less than 12 months, Unrealized Loss, held to maturity	(567)	(4,199)
12 months or more, Fair Value, held to maturity	95,367
12 months or more, Unrealized Loss, held to maturity	(1,322)
Total Fair Value, held to maturity	188,384	280,497
Total Unrealized Loss, held to maturity	(1,889)	(4,199)
Obligations of States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	4,904	90,825
Less than 12 months, Unrealized Loss	(35)	(4,396)
12 months or more, Fair Value	17,085
12 months or more, Unrealized Loss	(294)
Total Fair Value	21,989	90,825
Total Unrealized Loss	(329)	(4,396)
Less than 12 months, Fair Value, held to maturity	1,488	9,984
Less than 12 months, Unrealized Loss, held to maturity	(7)	(191)
12 months or more, Fair Value, held to maturity	2,637
12 months or more, Unrealized Loss, held to maturity	(30)
Total Fair Value, held to maturity	4,125	9,984
Total Unrealized Loss, held to maturity	(37)	(191)
Marketable Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value		2,938
Less than 12 months, Unrealized Loss		(62)
12 months or more, Fair Value	2,938
12 months or more, Unrealized Loss	(62)
Total Fair Value	2,938	2,938
Total Unrealized Loss	$ (62)	$ (62)

Loans - Summary of Loan Balance

Loans - Summary of Loan Balances (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	$ 3,015,165	$ 2,759,593	$ 2,522,937
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	3,015,165	2,759,593	2,522,937
Construction:
Total loans, net of unamortized deferred loan fees and discounts	3,015,165	2,759,593	2,522,937
Commercial	3,038,472	2,785,312
Unamortized net deferred loan fees	(8,651)	(6,916)
Discounts to principal balance of loans owed, net of charge-offs	(14,656)	(18,803)
Total loans, net of unamortized deferred loan fees and discounts	3,015,165	2,759,593	2,522,937
Noncovered loans	3,015,165	2,756,417
Covered loans		3,176
Total loans, net of unamortized deferred loan fees and discounts	3,015,165	2,759,593	2,522,937
Allowance for loan losses	(30,323)	(32,503)	(36,011)	$ (36,585)
Mortgage Loans on Real Estate [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	2,300,322	2,053,464
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	2,300,322	2,053,464
Construction:
Total loans, net of unamortized deferred loan fees and discounts	2,300,322	2,053,464
Total loans, net of unamortized deferred loan fees and discounts	2,300,322	2,053,464
Total loans, net of unamortized deferred loan fees and discounts	2,300,322	2,053,464
Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	356,874	366,663
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	356,874	366,663
Construction:
Total loans, net of unamortized deferred loan fees and discounts	356,874	366,663
Total loans, net of unamortized deferred loan fees and discounts	356,874	366,663
Total loans, net of unamortized deferred loan fees and discounts	356,874	366,663
Commercial Portfolio Segment [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	220,412	217,047
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	220,412	217,047
Construction:
Total loans, net of unamortized deferred loan fees and discounts	220,412	217,047
Total loans, net of unamortized deferred loan fees and discounts	220,412	217,047
Total loans, net of unamortized deferred loan fees and discounts	220,412	217,047
Construction [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	137,557	122,419
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	137,557	122,419
Construction:
Total loans, net of unamortized deferred loan fees and discounts	137,557	122,419
Total loans, net of unamortized deferred loan fees and discounts	137,557	122,419
Total loans, net of unamortized deferred loan fees and discounts	137,557	122,419
Residential 1-4 Family [Member] | Mortgage Loans on Real Estate [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	385,426	368,343
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	385,426	368,343
Construction:
Total loans, net of unamortized deferred loan fees and discounts	385,426	368,343
Total loans, net of unamortized deferred loan fees and discounts	385,426	368,343
Total loans, net of unamortized deferred loan fees and discounts	385,426	368,343
Home Equity Loans [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	43,031	46,182	40,362
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	43,031	46,182	40,362
Construction:
Total loans, net of unamortized deferred loan fees and discounts	43,031	46,182	40,362
Total loans, net of unamortized deferred loan fees and discounts	43,031	46,182	40,362
Total loans, net of unamortized deferred loan fees and discounts	43,031	46,182	40,362
Allowance for loan losses	(1,841)	(2,644)	(3,177)	(1,797)
Other Consumer [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	25,155	30,766	32,429
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	25,155	30,766	32,429
Construction:
Total loans, net of unamortized deferred loan fees and discounts	25,155	30,766	32,429
Total loans, net of unamortized deferred loan fees and discounts	25,155	30,766	32,429
Total loans, net of unamortized deferred loan fees and discounts	25,155	30,766	32,429
Allowance for loan losses	(586)	(622)	(688)	(719)
Commercial [Member] | Mortgage Loans on Real Estate [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	1,914,896	1,685,121	1,497,567
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	1,914,896	1,685,121	1,497,567
Construction:
Total loans, net of unamortized deferred loan fees and discounts	1,914,896	1,685,121	1,497,567
Total loans, net of unamortized deferred loan fees and discounts	1,914,896	1,685,121	1,497,567
Total loans, net of unamortized deferred loan fees and discounts	1,914,896	1,685,121	1,497,567
Allowance for loan losses	(11,441)	(11,517)	(11,015)	(9,227)
Commercial [Member] | Construction [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	69,627	66,990	74,774
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	69,627	66,990	74,774
Construction:
Total loans, net of unamortized deferred loan fees and discounts	69,627	66,990	74,774
Total loans, net of unamortized deferred loan fees and discounts	69,627	66,990	74,774
Total loans, net of unamortized deferred loan fees and discounts	69,627	66,990	74,774
Allowance for loan losses	(642)	(680)	(812)	(411)
Home Equity Lines of Credit [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	288,688	289,715	322,492
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	288,688	289,715	322,492
Construction:
Total loans, net of unamortized deferred loan fees and discounts	288,688	289,715	322,492
Total loans, net of unamortized deferred loan fees and discounts	288,688	289,715	322,492
Total loans, net of unamortized deferred loan fees and discounts	288,688	289,715	322,492
Allowance for loan losses	(5,800)	(7,044)	(11,253)	(15,676)
Residential [Member] | Mortgage Loans on Real Estate [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	385,426	368,343	314,265
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	385,426	368,343	314,265
Construction:
Total loans, net of unamortized deferred loan fees and discounts	385,426	368,343	314,265
Total loans, net of unamortized deferred loan fees and discounts	385,426	368,343	314,265
Total loans, net of unamortized deferred loan fees and discounts	385,426	368,343	314,265
Allowance for loan losses	(2,317)	(2,748)	(2,896)	(3,086)
Residential [Member] | Construction [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	67,930	55,429	46,135
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	67,930	55,429	46,135
Construction:
Total loans, net of unamortized deferred loan fees and discounts	67,930	55,429	46,135
Total loans, net of unamortized deferred loan fees and discounts	67,930	55,429	46,135
Total loans, net of unamortized deferred loan fees and discounts	67,930	55,429	46,135
Allowance for loan losses	(1,184)	(1,417)	$ (899)	$ (1,434)
Originated [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	2,690,402	2,356,327
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	2,690,402	2,356,327
Construction:
Total loans, net of unamortized deferred loan fees and discounts	2,690,402	2,356,327
Commercial	2,699,053	2,363,243
Unamortized net deferred loan fees	(8,651)	(6,916)
Total loans, net of unamortized deferred loan fees and discounts	2,690,402	2,356,327
Noncovered loans	2,690,402	2,356,327
Total loans, net of unamortized deferred loan fees and discounts	2,690,402	2,356,327
Allowance for loan losses	(29,122)	(28,141)
Originated [Member] | Mortgage Loans on Real Estate [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	2,011,032	1,710,367
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	2,011,032	1,710,367
Construction:
Total loans, net of unamortized deferred loan fees and discounts	2,011,032	1,710,367
Total loans, net of unamortized deferred loan fees and discounts	2,011,032	1,710,367
Total loans, net of unamortized deferred loan fees and discounts	2,011,032	1,710,367
Originated [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	332,649	332,493
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	332,649	332,493
Construction:
Total loans, net of unamortized deferred loan fees and discounts	332,649	332,493
Total loans, net of unamortized deferred loan fees and discounts	332,649	332,493
Total loans, net of unamortized deferred loan fees and discounts	332,649	332,493
Originated [Member] | Commercial Portfolio Segment [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	209,437	200,735
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	209,437	200,735
Construction:
Total loans, net of unamortized deferred loan fees and discounts	209,437	200,735
Total loans, net of unamortized deferred loan fees and discounts	209,437	200,735
Total loans, net of unamortized deferred loan fees and discounts	209,437	200,735
Originated [Member] | Construction [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	137,284	112,732
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	137,284	112,732
Construction:
Total loans, net of unamortized deferred loan fees and discounts	137,284	112,732
Total loans, net of unamortized deferred loan fees and discounts	137,284	112,732
Total loans, net of unamortized deferred loan fees and discounts	137,284	112,732
Originated [Member] | Residential 1-4 Family [Member] | Mortgage Loans on Real Estate [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	320,522	284,539
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	320,522	284,539
Construction:
Total loans, net of unamortized deferred loan fees and discounts	320,522	284,539
Total loans, net of unamortized deferred loan fees and discounts	320,522	284,539
Total loans, net of unamortized deferred loan fees and discounts	320,522	284,539
Originated [Member] | Home Equity Loans [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	39,848	40,736
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	39,848	40,736
Construction:
Total loans, net of unamortized deferred loan fees and discounts	39,848	40,736
Total loans, net of unamortized deferred loan fees and discounts	39,848	40,736
Total loans, net of unamortized deferred loan fees and discounts	39,848	40,736
Originated [Member] | Other Consumer [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	22,859	28,167
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	22,859	28,167
Construction:
Total loans, net of unamortized deferred loan fees and discounts	22,859	28,167
Total loans, net of unamortized deferred loan fees and discounts	22,859	28,167
Total loans, net of unamortized deferred loan fees and discounts	22,859	28,167
Originated [Member] | Commercial [Member] | Mortgage Loans on Real Estate [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	1,690,510	1,425,828
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	1,690,510	1,425,828
Construction:
Total loans, net of unamortized deferred loan fees and discounts	1,690,510	1,425,828
Total loans, net of unamortized deferred loan fees and discounts	1,690,510	1,425,828
Total loans, net of unamortized deferred loan fees and discounts	1,690,510	1,425,828
Originated [Member] | Commercial [Member] | Construction [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	69,364	58,119
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	69,364	58,119
Construction:
Total loans, net of unamortized deferred loan fees and discounts	69,364	58,119
Total loans, net of unamortized deferred loan fees and discounts	69,364	58,119
Total loans, net of unamortized deferred loan fees and discounts	69,364	58,119
Originated [Member] | Home Equity Lines of Credit [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	269,942	263,590
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	269,942	263,590
Construction:
Total loans, net of unamortized deferred loan fees and discounts	269,942	263,590
Total loans, net of unamortized deferred loan fees and discounts	269,942	263,590
Total loans, net of unamortized deferred loan fees and discounts	269,942	263,590
Originated [Member] | Residential [Member] | Construction [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	67,920	54,613
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	67,920	54,613
Construction:
Total loans, net of unamortized deferred loan fees and discounts	67,920	54,613
Total loans, net of unamortized deferred loan fees and discounts	67,920	54,613
Total loans, net of unamortized deferred loan fees and discounts	67,920	54,613
PNCI [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	309,203	378,222
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	309,203	378,222
Construction:
Total loans, net of unamortized deferred loan fees and discounts	309,203	378,222
Commercial	316,238	388,139
Discounts to principal balance of loans owed, net of charge-offs	(7,035)	(9,917)
Total loans, net of unamortized deferred loan fees and discounts	309,203	378,222
Noncovered loans	309,203	378,222
Total loans, net of unamortized deferred loan fees and discounts	309,203	378,222
Allowance for loan losses	(929)	(1,665)
PNCI [Member] | Mortgage Loans on Real Estate [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	279,342	328,826
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	279,342	328,826
Construction:
Total loans, net of unamortized deferred loan fees and discounts	279,342	328,826
Total loans, net of unamortized deferred loan fees and discounts	279,342	328,826
Total loans, net of unamortized deferred loan fees and discounts	279,342	328,826
PNCI [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	21,197	28,063
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	21,197	28,063
Construction:
Total loans, net of unamortized deferred loan fees and discounts	21,197	28,063
Total loans, net of unamortized deferred loan fees and discounts	21,197	28,063
Total loans, net of unamortized deferred loan fees and discounts	21,197	28,063
PNCI [Member] | Commercial Portfolio Segment [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	8,391	12,321
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	8,391	12,321
Construction:
Total loans, net of unamortized deferred loan fees and discounts	8,391	12,321
Total loans, net of unamortized deferred loan fees and discounts	8,391	12,321
Total loans, net of unamortized deferred loan fees and discounts	8,391	12,321
PNCI [Member] | Construction [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	273	9,012
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	273	9,012
Construction:
Total loans, net of unamortized deferred loan fees and discounts	273	9,012
Total loans, net of unamortized deferred loan fees and discounts	273	9,012
Total loans, net of unamortized deferred loan fees and discounts	273	9,012
PNCI [Member] | Residential 1-4 Family [Member] | Mortgage Loans on Real Estate [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	63,519	82,335
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	63,519	82,335
Construction:
Total loans, net of unamortized deferred loan fees and discounts	63,519	82,335
Total loans, net of unamortized deferred loan fees and discounts	63,519	82,335
Total loans, net of unamortized deferred loan fees and discounts	63,519	82,335
PNCI [Member] | Home Equity Loans [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	2,698	3,764
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	2,698	3,764
Construction:
Total loans, net of unamortized deferred loan fees and discounts	2,698	3,764
Total loans, net of unamortized deferred loan fees and discounts	2,698	3,764
Total loans, net of unamortized deferred loan fees and discounts	2,698	3,764
PNCI [Member] | Other Consumer [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	2,251	2,534
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	2,251	2,534
Construction:
Total loans, net of unamortized deferred loan fees and discounts	2,251	2,534
Total loans, net of unamortized deferred loan fees and discounts	2,251	2,534
Total loans, net of unamortized deferred loan fees and discounts	2,251	2,534
PNCI [Member] | Commercial [Member] | Mortgage Loans on Real Estate [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	215,823	246,491
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	215,823	246,491
Construction:
Total loans, net of unamortized deferred loan fees and discounts	215,823	246,491
Total loans, net of unamortized deferred loan fees and discounts	215,823	246,491
Total loans, net of unamortized deferred loan fees and discounts	215,823	246,491
PNCI [Member] | Commercial [Member] | Construction [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	263	8,871
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	263	8,871
Construction:
Total loans, net of unamortized deferred loan fees and discounts	263	8,871
Total loans, net of unamortized deferred loan fees and discounts	263	8,871
Total loans, net of unamortized deferred loan fees and discounts	263	8,871
PNCI [Member] | Home Equity Lines of Credit [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	16,248	21,765
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	16,248	21,765
Construction:
Total loans, net of unamortized deferred loan fees and discounts	16,248	21,765
Total loans, net of unamortized deferred loan fees and discounts	16,248	21,765
Total loans, net of unamortized deferred loan fees and discounts	16,248	21,765
PNCI [Member] | Residential [Member] | Construction [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	10	141
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	10	141
Construction:
Total loans, net of unamortized deferred loan fees and discounts	10	141
Total loans, net of unamortized deferred loan fees and discounts	10	141
Total loans, net of unamortized deferred loan fees and discounts	10	141
PCI - Cash Basis [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	2,069	2,983
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	2,069	2,983
Construction:
Total loans, net of unamortized deferred loan fees and discounts	2,069	2,983
Commercial	5,863	8,280
Discounts to principal balance of loans owed, net of charge-offs	(3,794)	(5,297)
Total loans, net of unamortized deferred loan fees and discounts	2,069	2,983
Noncovered loans	2,069	2,983
Total loans, net of unamortized deferred loan fees and discounts	2,069	2,983
Allowance for loan losses	(17)	(17)
PCI - Cash Basis [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	2,069	2,983
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	2,069	2,983
Construction:
Total loans, net of unamortized deferred loan fees and discounts	2,069	2,983
Total loans, net of unamortized deferred loan fees and discounts	2,069	2,983
Total loans, net of unamortized deferred loan fees and discounts	2,069	2,983
PCI - Cash Basis [Member] | Home Equity Lines of Credit [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	2,069	2,983
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	2,069	2,983
Construction:
Total loans, net of unamortized deferred loan fees and discounts	2,069	2,983
Total loans, net of unamortized deferred loan fees and discounts	2,069	2,983
Total loans, net of unamortized deferred loan fees and discounts	2,069	2,983
PCI - Other [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	13,491	22,061
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	13,491	22,061
Construction:
Total loans, net of unamortized deferred loan fees and discounts	13,491	22,061
Commercial	17,318	25,650
Discounts to principal balance of loans owed, net of charge-offs	(3,827)	(3,589)
Total loans, net of unamortized deferred loan fees and discounts	13,491	22,061
Noncovered loans	13,491	18,885
Covered loans		3,176
Total loans, net of unamortized deferred loan fees and discounts	13,491	22,061
Allowance for loan losses	(255)	(2,680)
PCI - Other [Member] | Mortgage Loans on Real Estate [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	9,948	14,271
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	9,948	14,271
Construction:
Total loans, net of unamortized deferred loan fees and discounts	9,948	14,271
Total loans, net of unamortized deferred loan fees and discounts	9,948	14,271
Total loans, net of unamortized deferred loan fees and discounts	9,948	14,271
PCI - Other [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	959	3,124
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	959	3,124
Construction:
Total loans, net of unamortized deferred loan fees and discounts	959	3,124
Total loans, net of unamortized deferred loan fees and discounts	959	3,124
Total loans, net of unamortized deferred loan fees and discounts	959	3,124
PCI - Other [Member] | Commercial Portfolio Segment [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	2,584	3,991
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	2,584	3,991
Construction:
Total loans, net of unamortized deferred loan fees and discounts	2,584	3,991
Total loans, net of unamortized deferred loan fees and discounts	2,584	3,991
Total loans, net of unamortized deferred loan fees and discounts	2,584	3,991
PCI - Other [Member] | Construction [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts		675
Consumer:
Total loans, net of unamortized deferred loan fees and discounts		675
Construction:
Total loans, net of unamortized deferred loan fees and discounts		675
Total loans, net of unamortized deferred loan fees and discounts		675
Total loans, net of unamortized deferred loan fees and discounts		675
PCI - Other [Member] | Residential 1-4 Family [Member] | Mortgage Loans on Real Estate [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	1,385	1,469
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	1,385	1,469
Construction:
Total loans, net of unamortized deferred loan fees and discounts	1,385	1,469
Total loans, net of unamortized deferred loan fees and discounts	1,385	1,469
Total loans, net of unamortized deferred loan fees and discounts	1,385	1,469
PCI - Other [Member] | Home Equity Loans [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	485	1,682
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	485	1,682
Construction:
Total loans, net of unamortized deferred loan fees and discounts	485	1,682
Total loans, net of unamortized deferred loan fees and discounts	485	1,682
Total loans, net of unamortized deferred loan fees and discounts	485	1,682
PCI - Other [Member] | Other Consumer [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	45	65
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	45	65
Construction:
Total loans, net of unamortized deferred loan fees and discounts	45	65
Total loans, net of unamortized deferred loan fees and discounts	45	65
Total loans, net of unamortized deferred loan fees and discounts	45	65
PCI - Other [Member] | Commercial [Member] | Mortgage Loans on Real Estate [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	8,563	12,802
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	8,563	12,802
Construction:
Total loans, net of unamortized deferred loan fees and discounts	8,563	12,802
Total loans, net of unamortized deferred loan fees and discounts	8,563	12,802
Total loans, net of unamortized deferred loan fees and discounts	8,563	12,802
PCI - Other [Member] | Home Equity Lines of Credit [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	429	1,377
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	429	1,377
Construction:
Total loans, net of unamortized deferred loan fees and discounts	429	1,377
Total loans, net of unamortized deferred loan fees and discounts	429	1,377
Total loans, net of unamortized deferred loan fees and discounts	$ 429	1,377
PCI - Other [Member] | Residential [Member] | Construction [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts		675
Consumer:
Total loans, net of unamortized deferred loan fees and discounts		675
Construction:
Total loans, net of unamortized deferred loan fees and discounts		675
Total loans, net of unamortized deferred loan fees and discounts		675
Total loans, net of unamortized deferred loan fees and discounts		$ 675

Loans - Change in Accretable Yi

Loans - Change in Accretable Yield for PCI (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Change in accretable yield:
Balance at beginning of period	$ 10,348	$ 13,255
Accretion to interest income	(2,809)	(4,011)
Reclassification (to) from nonaccretable difference	(3,277)	1,104
Balance at end of period	$ 4,262	$ 10,348

Allowance for Loan Losses - Sum

Allowance for Loan Losses - Summary of Activity in Allowance for Loan Losses, and Ending Balance of Loans, Net of Unearned Fees for Periods Indicated (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	$ 3,015,165	$ 2,759,593	$ 2,522,937
Individ. evaluated for impairment	28,234	28,140	50,105
Loans pooled for evaluation	2,971,371	2,706,409	2,432,628
Beginning balance	32,503	36,011	36,585
Charge-offs	(4,410)	(3,230)	(2,816)
Recoveries	2,141	5,692	4,452
(Benefit) provision	89	(5,970)	(2,210)
Ending balance	30,323	32,503	36,011
Ending balance:
Individ. evaluated for impairment	2,699	2,046	2,891
Loans pooled for evaluation	27,352	27,760	30,227
Mortgage Loans on Real Estate [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	2,300,322	2,053,464
Mortgage Loans on Real Estate [Member] | Residential [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	385,426	368,343	314,265
Individ. evaluated for impairment	5,298	4,094	6,767
Loans pooled for evaluation	378,743	362,780	305,353
Beginning balance	2,748	2,896	3,086
Charge-offs	(60)	(321)	(224)
Recoveries		880	204
(Benefit) provision	(371)	(707)	(170)
Ending balance	2,317	2,748	2,896
Ending balance:
Individ. evaluated for impairment	230	258	335
Loans pooled for evaluation	1,932	2,304	2,501
Mortgage Loans on Real Estate [Member] | Commercial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	1,914,896	1,685,121	1,497,567
Individ. evaluated for impairment	13,911	15,081	32,407
Loans pooled for evaluation	1,892,422	1,657,238	1,442,100
Beginning balance	11,517	11,015	9,227
Charge-offs	(186)	(827)
Recoveries	397	920	243
(Benefit) provision	(287)	409	1,545
Ending balance	11,441	11,517	11,015
Ending balance:
Individ. evaluated for impairment	30	4	396
Loans pooled for evaluation	11,351	10,064	9,167
Consumer [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	356,874	366,663
Consumer [Member] | Home Equity Lines of Credit [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	288,688	289,715	322,492
Individ. evaluated for impairment	2,688	3,196	5,747
Loans pooled for evaluation	283,502	282,159	309,007
Beginning balance	7,044	11,253	15,676
Charge-offs	(98)	(585)	(694)
Recoveries	698	2,317	666
(Benefit) provision	(1,844)	(5,941)	(4,395)
Ending balance	5,800	7,044	11,253
Ending balance:
Individ. evaluated for impairment	427	411	605
Loans pooled for evaluation	5,356	6,616	10,423
Consumer and Industrial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	220,412	217,047	194,913
Individ. evaluated for impairment	4,470	4,096	2,671
Loans pooled for evaluation	213,358	208,960	187,393
Beginning balance	5,831	5,271	4,226
Charge-offs	(1,444)	(455)	(680)
Recoveries	428	404	677
(Benefit) provision	1,697	611	1,048
Ending balance	6,512	5,831	5,271
Ending balance:
Individ. evaluated for impairment	1,848	1,130	1,187
Loans pooled for evaluation	4,624	3,765	2,983
Construction [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	137,557	122,419
Construction [Member] | Residential [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	67,930	55,429	46,135
Individ. evaluated for impairment	140	11	4
Loans pooled for evaluation	67,790	54,743	45,410
Beginning balance	1,417	899	1,434
Charge-offs	(1,104)
Recoveries		54	1,728
(Benefit) provision	871	464	(2,263)
Ending balance	1,184	1,417	899
Ending balance:
Loans pooled for evaluation	1,184	1,372	844
Construction [Member] | Commercial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	69,627	66,990	74,774
Individ. evaluated for impairment			490
Loans pooled for evaluation	69,627	66,990	74,284
Beginning balance	680	812	411
Recoveries	1	78	140
(Benefit) provision	(39)	(210)	261
Ending balance	642	680	812
Ending balance:
Loans pooled for evaluation	642	680	812
Home Equity Loans [Member] | Consumer [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	43,031	46,182	40,362
Individ. evaluated for impairment	1,470	1,508	1,731
Loans pooled for evaluation	41,076	42,992	37,004
Beginning balance	2,644	3,177	1,797
Charge-offs	(332)	(219)	(242)
Recoveries	242	590	252
(Benefit) provision	(713)	(904)	1,370
Ending balance	1,841	2,644	3,177
Ending balance:
Individ. evaluated for impairment	107	215	294
Loans pooled for evaluation	1,734	2,365	2,883
Auto Indirect [Member] | Consumer [Member]
Loans and Leases Receivable Disclosure [Line Items]
Beginning balance			9
Charge-offs			(4)
Recoveries			42
(Benefit) provision			(47)
Other Consumer [Member] | Consumer [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	25,155	30,766	32,429
Individ. evaluated for impairment	257	154	288
Loans pooled for evaluation	24,853	30,547	32,077
Beginning balance	622	688	719
Charge-offs	(1,186)	(823)	(972)
Recoveries	375	449	500
(Benefit) provision	775	308	441
Ending balance	586	622	688
Ending balance:
Individ. evaluated for impairment	57	28	74
Loans pooled for evaluation	529	594	614
Receivables Acquired with Deteriorated Credit Quality [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	15,560	25,044	40,204
Ending balance:
Loans acquired with deteriorated credit quality	272	2,697	2,893
Receivables Acquired with Deteriorated Credit Quality [Member] | Mortgage Loans on Real Estate [Member] | Residential [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	1,385	1,469	2,145
Ending balance:
Loans acquired with deteriorated credit quality	155	186	60
Receivables Acquired with Deteriorated Credit Quality [Member] | Mortgage Loans on Real Estate [Member] | Commercial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	8,563	12,802	23,060
Ending balance:
Loans acquired with deteriorated credit quality	60	1,449	1,452
Receivables Acquired with Deteriorated Credit Quality [Member] | Consumer [Member] | Home Equity Lines of Credit [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	2,498	4,360	7,738
Ending balance:
Loans acquired with deteriorated credit quality	17	17	225
Receivables Acquired with Deteriorated Credit Quality [Member] | Consumer and Industrial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	2,584	3,991	4,849
Ending balance:
Loans acquired with deteriorated credit quality	40	936	1,101
Receivables Acquired with Deteriorated Credit Quality [Member] | Construction [Member] | Residential [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts		675	721
Ending balance:
Loans acquired with deteriorated credit quality		45	55
Receivables Acquired with Deteriorated Credit Quality [Member] | Home Equity Loans [Member] | Consumer [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	485	1,682	1,627
Ending balance:
Loans acquired with deteriorated credit quality		64
Receivables Acquired with Deteriorated Credit Quality [Member] | Other Consumer [Member] | Consumer [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	$ 45	$ 65	$ 64

Allowance for Loan Losses - Pre

Allowance for Loan Losses - Presentation of Credit Quality Indicators (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	$ 3,015,165	$ 2,759,593	$ 2,522,937
Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	2,690,402	2,356,327
PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	309,203	378,222
PCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	15,560	25,044
Pass [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	2,617,171	2,305,293
Pass [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	293,331	360,043
Special Mention [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	38,662	27,571
Special Mention [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	12,408	8,549
Substandard [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	34,569	23,463
Substandard [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	3,464	9,630
Mortgage Loans on Real Estate [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	2,300,322	2,053,464
Mortgage Loans on Real Estate [Member] | Residential [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	385,426	368,343	314,265
Mortgage Loans on Real Estate [Member] | Residential [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	320,522	284,539
Mortgage Loans on Real Estate [Member] | Residential [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	63,519	82,335
Mortgage Loans on Real Estate [Member] | Residential [Member] | PCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	1,385	1,469
Mortgage Loans on Real Estate [Member] | Residential [Member] | Pass [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	315,120	278,635
Mortgage Loans on Real Estate [Member] | Residential [Member] | Pass [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	61,411	79,000
Mortgage Loans on Real Estate [Member] | Residential [Member] | Special Mention [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	2,234	2,992
Mortgage Loans on Real Estate [Member] | Residential [Member] | Special Mention [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	218	1,849
Mortgage Loans on Real Estate [Member] | Residential [Member] | Substandard [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	3,168	2,912
Mortgage Loans on Real Estate [Member] | Residential [Member] | Substandard [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	1,890	1,486
Mortgage Loans on Real Estate [Member] | Commercial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	1,914,896	1,685,121	1,497,567
Mortgage Loans on Real Estate [Member] | Commercial [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	1,690,510	1,425,828
Mortgage Loans on Real Estate [Member] | Commercial [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	215,823	246,491
Mortgage Loans on Real Estate [Member] | Commercial [Member] | PCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	8,563	12,802
Mortgage Loans on Real Estate [Member] | Commercial [Member] | Pass [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	1,649,333	1,399,936
Mortgage Loans on Real Estate [Member] | Commercial [Member] | Pass [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	203,751	233,326
Mortgage Loans on Real Estate [Member] | Commercial [Member] | Special Mention [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	18,434	14,341
Mortgage Loans on Real Estate [Member] | Commercial [Member] | Special Mention [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	11,513	5,925
Mortgage Loans on Real Estate [Member] | Commercial [Member] | Substandard [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	22,743	11,551
Mortgage Loans on Real Estate [Member] | Commercial [Member] | Substandard [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	559	7,240
Consumer [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	356,874	366,663
Consumer [Member] | Home Equity Lines of Credit [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	288,688	289,715	322,492
Consumer [Member] | Home Equity Lines of Credit [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	269,942	263,590
Consumer [Member] | Home Equity Lines of Credit [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	16,248	21,765
Consumer [Member] | Home Equity Lines of Credit [Member] | PCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	2,498	4,360
Consumer [Member] | Home Equity Lines of Credit [Member] | Pass [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	265,345	258,024
Consumer [Member] | Home Equity Lines of Credit [Member] | Pass [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	14,866	20,442
Consumer [Member] | Home Equity Lines of Credit [Member] | Special Mention [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	2,558	2,518
Consumer [Member] | Home Equity Lines of Credit [Member] | Special Mention [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	450	509
Consumer [Member] | Home Equity Lines of Credit [Member] | Substandard [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	2,039	3,048
Consumer [Member] | Home Equity Lines of Credit [Member] | Substandard [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	932	814
Consumer [Member] | Home Equity Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	43,031	46,182	40,362
Consumer [Member] | Home Equity Loans [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	39,848	40,736
Consumer [Member] | Home Equity Loans [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	2,698	3,764
Consumer [Member] | Home Equity Loans [Member] | PCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	485	1,682
Consumer [Member] | Home Equity Loans [Member] | Pass [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	37,428	37,844
Consumer [Member] | Home Equity Loans [Member] | Pass [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	2,433	3,506
Consumer [Member] | Home Equity Loans [Member] | Special Mention [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	800	891
Consumer [Member] | Home Equity Loans [Member] | Special Mention [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	188	173
Consumer [Member] | Home Equity Loans [Member] | Substandard [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	1,620	2,001
Consumer [Member] | Home Equity Loans [Member] | Substandard [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	77	85
Consumer [Member] | Other Consumer [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	25,155	30,766	32,429
Consumer [Member] | Other Consumer [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	22,859	28,167
Consumer [Member] | Other Consumer [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	2,251	2,534
Consumer [Member] | Other Consumer [Member] | PCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	45	65
Consumer [Member] | Other Consumer [Member] | Pass [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	22,432	27,542
Consumer [Member] | Other Consumer [Member] | Pass [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	2,207	2,437
Consumer [Member] | Other Consumer [Member] | Special Mention [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	272	385
Consumer [Member] | Other Consumer [Member] | Special Mention [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	38	92
Consumer [Member] | Other Consumer [Member] | Substandard [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	155	240
Consumer [Member] | Other Consumer [Member] | Substandard [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	6	5
Consumer and Industrial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	220,412	217,047	194,913
Consumer and Industrial [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	209,437	200,735
Consumer and Industrial [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	8,391	12,321
Consumer and Industrial [Member] | PCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	2,584	3,991
Consumer and Industrial [Member] | Pass [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	195,208	190,902
Consumer and Industrial [Member] | Pass [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	8,390	12,320
Consumer and Industrial [Member] | Special Mention [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	9,492	6,133
Consumer and Industrial [Member] | Special Mention [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	1	1
Consumer and Industrial [Member] | Substandard [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	4,737	3,700
Construction [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	137,557	122,419
Construction [Member] | Residential [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	67,930	55,429	46,135
Construction [Member] | Residential [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	67,920	54,613
Construction [Member] | Residential [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	10	141
Construction [Member] | Residential [Member] | PCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts		675
Construction [Member] | Residential [Member] | Pass [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	67,813	54,602
Construction [Member] | Residential [Member] | Pass [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	10	141
Construction [Member] | Residential [Member] | Substandard [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	107	11
Construction [Member] | Commercial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	69,627	66,990	$ 74,774
Construction [Member] | Commercial [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	69,364	58,119
Construction [Member] | Commercial [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	263	8,871
Construction [Member] | Commercial [Member] | Pass [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	64,492	57,808
Construction [Member] | Commercial [Member] | Pass [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	263	8,871
Construction [Member] | Commercial [Member] | Special Mention [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	$ 4,872	$ 311

Allowance for Loan Losses - Add

Allowance for Loan Losses - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017USD ($)Category	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Loans and Leases Receivable Disclosure [Line Items]
Number of categories occupied under commercial real estate loans | Category	2
Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Impaired TDR Loans	$ 12,517,000	$ 12,371,000	$ 29,269,000
Additional funds in TDR	1,000	25,000	35,000
PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Impaired TDR Loans	1,352,000	1,324,000	1,396,000
Obligations to lend additional funds on TDR	$ 0	$ 0	$ 0
Minimum [Member]
Loans and Leases Receivable Disclosure [Line Items]
Period of collateral payment of loan	3 months
Maximum [Member]
Loans and Leases Receivable Disclosure [Line Items]
Period of collateral payment of loan	12 months

Allowance for Loan Losses - Ana

Allowance for Loan Losses - Analysis of Past Due and Nonaccrual Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	$ 8,927	$ 8,687
Current	2,681,475	2,347,640
Total orig. loans	2,690,402	2,356,327
Nonaccrual loans	15,462	12,894
PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	2,682	2,600
Current	306,521	375,622
Total orig. loans	309,203	378,222
> 90 Days and still accruing	281
Nonaccrual loans	1,463	2,834
30-59 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	3,983	4,354
30-59 Days [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	1,899	1,896
60-89 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	2,426	2,586
60-89 Days [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	344
> 90 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	2,518	1,747
> 90 Days [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	439	704
Mortgage Loans on Real Estate [Member] | Residential [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	2,493	821
Current	318,029	283,718
Total orig. loans	320,522	284,539
Nonaccrual loans	1,725	255
Mortgage Loans on Real Estate [Member] | Residential [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	1,694	1,531
Current	61,825	80,804
Total orig. loans	63,519	82,335
> 90 Days and still accruing	81
Nonaccrual loans	1,012	194
Mortgage Loans on Real Estate [Member] | Commercial [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	1,145	1,920
Current	1,689,365	1,423,908
Total orig. loans	1,690,510	1,425,828
Nonaccrual loans	8,144	7,651
Mortgage Loans on Real Estate [Member] | Commercial [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	70	154
Current	215,753	246,337
Total orig. loans	215,823	246,491
Nonaccrual loans		1,826
Mortgage Loans on Real Estate [Member] | 30-59 Days [Member] | Residential [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	1,740	552
Mortgage Loans on Real Estate [Member] | 30-59 Days [Member] | Residential [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	1,495	1,510
Mortgage Loans on Real Estate [Member] | 30-59 Days [Member] | Commercial [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	158	317
Mortgage Loans on Real Estate [Member] | 30-59 Days [Member] | Commercial [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	70	73
Mortgage Loans on Real Estate [Member] | 60-89 Days [Member] | Residential [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	510	269
Mortgage Loans on Real Estate [Member] | 60-89 Days [Member] | Residential [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	90
Mortgage Loans on Real Estate [Member] | 60-89 Days [Member] | Commercial [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	987	1,387
Mortgage Loans on Real Estate [Member] | > 90 Days [Member] | Residential [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	243
Mortgage Loans on Real Estate [Member] | > 90 Days [Member] | Residential [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	109	21
Mortgage Loans on Real Estate [Member] | > 90 Days [Member] | Commercial [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		216
Mortgage Loans on Real Estate [Member] | > 90 Days [Member] | Commercial [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		81
Consumer [Member] | Home Equity Lines of Credit [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	948	1,441
Current	268,994	262,149
Total orig. loans	269,942	263,590
Nonaccrual loans	811	1,211
Consumer [Member] | Home Equity Lines of Credit [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	856	863
Current	15,392	20,902
Total orig. loans	16,248	21,765
> 90 Days and still accruing	200
Nonaccrual loans	402	742
Consumer [Member] | 30-59 Days [Member] | Home Equity Lines of Credit [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	528	754
Consumer [Member] | 30-59 Days [Member] | Home Equity Lines of Credit [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	298	274
Consumer [Member] | 60-89 Days [Member] | Home Equity Lines of Credit [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	48
Consumer [Member] | 60-89 Days [Member] | Home Equity Lines of Credit [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	228
Consumer [Member] | > 90 Days [Member] | Home Equity Lines of Credit [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	372	687
Consumer [Member] | > 90 Days [Member] | Home Equity Lines of Credit [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	330	589
Consumer [Member] | Home Equity Loans [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	991	1,225
Current	38,857	39,511
Total orig. loans	39,848	40,736
Nonaccrual loans	1,106	803
Consumer [Member] | Home Equity Loans [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	30	52
Current	2,668	3,712
Total orig. loans	2,698	3,764
Nonaccrual loans	44	67
Consumer [Member] | Home Equity Loans [Member] | 30-59 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	511	646
Consumer [Member] | Home Equity Loans [Member] | 30-59 Days [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	30	39
Consumer [Member] | Home Equity Loans [Member] | 60-89 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	107	395
Consumer [Member] | Home Equity Loans [Member] | > 90 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	373	184
Consumer [Member] | Home Equity Loans [Member] | > 90 Days [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		13
Consumer [Member] | Other Consumer [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	95	61
Current	22,764	28,106
Total orig. loans	22,859	28,167
Nonaccrual loans	7	33
Consumer [Member] | Other Consumer [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	32
Current	2,219	2,534
Total orig. loans	2,251	2,534
Nonaccrual loans	5	5
Consumer [Member] | Other Consumer [Member] | 30-59 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	56	16
Consumer [Member] | Other Consumer [Member] | 30-59 Days [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	6
Consumer [Member] | Other Consumer [Member] | 60-89 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	36	30
Consumer [Member] | Other Consumer [Member] | 60-89 Days [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	26
Consumer [Member] | Other Consumer [Member] | > 90 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	3	15
Consumer and Industrial [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	3,221	1,866
Current	206,216	198,869
Total orig. loans	209,437	200,735
Nonaccrual loans	3,669	2,930
Consumer and Industrial [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	8,391	12,321
Total orig. loans	8,391	12,321
Consumer and Industrial [Member] | 30-59 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	956	1,148
Consumer and Industrial [Member] | 60-89 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	738	84
Consumer and Industrial [Member] | > 90 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	1,527	634
Construction [Member] | Residential [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	34	932
Current	67,886	53,681
Total orig. loans	67,920	54,613
Nonaccrual loans		11
Construction [Member] | Residential [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	10	141
Total orig. loans	10	141
Construction [Member] | Commercial [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		421
Current	69,364	57,698
Total orig. loans	69,364	58,119
Construction [Member] | Commercial [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	263	8,871
Total orig. loans	263	8,871
Construction [Member] | 30-59 Days [Member] | Residential [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	$ 34	921
Construction [Member] | 60-89 Days [Member] | Commercial [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		421
Construction [Member] | > 90 Days [Member] | Residential [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		$ 11

Allowance for Loan Losses - Imp

Allowance for Loan Losses - Impaired Loans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Originated Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	$ 18,078	$ 17,701
Unpaid principal, With no related allowance recorded	18,850	18,641
Average recorded Investment, With no related allowance recorded	17,891	26,601
Interest income Recognized, With no related allowance recorded	774	757
Recorded investment, With an allowance recorded	7,188	6,285
Unpaid principal, With an allowance recorded	7,328	6,349
Related allowance, With an allowance recorded	2,232	1,544
Average recorded Investment, With an allowance recorded	6,735	7,100
Interest income Recognized, With an allowance recorded	278	206
PNCI Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	1,994	3,094
Unpaid principal, With no related allowance recorded	2,073	3,341
Average recorded Investment, With no related allowance recorded	2,545	3,075
Interest income Recognized, With no related allowance recorded	46	17
Recorded investment, With an allowance recorded	974	1,060
Unpaid principal, With an allowance recorded	975	1,060
Related allowance, With an allowance recorded	467	502
Average recorded Investment, With an allowance recorded	1,018	2,344
Interest income Recognized, With an allowance recorded	43	49
Mortgage Loans on Real Estate [Member] | Residential [Member] | Originated Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	2,058	1,820
Unpaid principal, With no related allowance recorded	2,109	1,829
Average recorded Investment, With no related allowance recorded	1,875	2,853
Interest income Recognized, With no related allowance recorded	85	92
Recorded investment, With an allowance recorded	1,881	1,551
Unpaid principal, With an allowance recorded	1,914	1,552
Related allowance, With an allowance recorded	230	180
Average recorded Investment, With an allowance recorded	1,626	1,779
Interest income Recognized, With an allowance recorded	58	65
Mortgage Loans on Real Estate [Member] | Residential [Member] | PNCI Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	1,359	463
Unpaid principal, With no related allowance recorded	1,404	486
Average recorded Investment, With no related allowance recorded	911	669
Interest income Recognized, With no related allowance recorded	24	7
Recorded investment, With an allowance recorded		259
Unpaid principal, With an allowance recorded		259
Related allowance, With an allowance recorded		79
Average recorded Investment, With an allowance recorded	130	130
Interest income Recognized, With an allowance recorded		10
Mortgage Loans on Real Estate [Member] | Commercial [Member] | Originated Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	13,101	12,898
Unpaid principal, With no related allowance recorded	13,360	13,145
Average recorded Investment, With no related allowance recorded	13,123	20,003
Interest income Recognized, With no related allowance recorded	609	570
Recorded investment, With an allowance recorded	810	357
Unpaid principal, With an allowance recorded	826	358
Related allowance, With an allowance recorded	30	4
Average recorded Investment, With an allowance recorded	728	888
Interest income Recognized, With an allowance recorded	36	22
Mortgage Loans on Real Estate [Member] | Commercial [Member] | PNCI Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded		1,826
Unpaid principal, With no related allowance recorded		2,031
Average recorded Investment, With no related allowance recorded	913	1,479
Average recorded Investment, With an allowance recorded	66	1,374
Consumer [Member] | Home Equity Lines of Credit [Member] | Originated Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	1,093	1,480
Unpaid principal, With no related allowance recorded	1,175	1,561
Average recorded Investment, With no related allowance recorded	1,287	2,221
Interest income Recognized, With no related allowance recorded	39	40
Recorded investment, With an allowance recorded	401	430
Unpaid principal, With an allowance recorded	406	440
Related allowance, With an allowance recorded	111	110
Average recorded Investment, With an allowance recorded	415	1,076
Interest income Recognized, With an allowance recorded	8	9
Consumer [Member] | Home Equity Lines of Credit [Member] | PNCI Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	591	735
Unpaid principal, With no related allowance recorded	612	746
Average recorded Investment, With no related allowance recorded	663	594
Interest income Recognized, With no related allowance recorded	22	9
Recorded investment, With an allowance recorded	603	551
Unpaid principal, With an allowance recorded	604	551
Related allowance, With an allowance recorded	316	300
Average recorded Investment, With an allowance recorded	577	579
Interest income Recognized, With an allowance recorded	26	27
Consumer [Member] | Home Equity Loans [Member] | Originated Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	1,107	715
Unpaid principal, With no related allowance recorded	1,429	1,135
Average recorded Investment, With no related allowance recorded	852	831
Interest income Recognized, With no related allowance recorded	14	6
Recorded investment, With an allowance recorded	198	594
Unpaid principal, With an allowance recorded	198	595
Related allowance, With an allowance recorded	10	107
Average recorded Investment, With an allowance recorded	341	634
Interest income Recognized, With an allowance recorded	10	31
Consumer [Member] | Home Equity Loans [Member] | PNCI Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	44	67
Unpaid principal, With no related allowance recorded	57	74
Average recorded Investment, With no related allowance recorded	56	69
Interest income Recognized, With no related allowance recorded		1
Recorded investment, With an allowance recorded	121	132
Unpaid principal, With an allowance recorded	121	132
Related allowance, With an allowance recorded	97	108
Average recorded Investment, With an allowance recorded	61	85
Interest income Recognized, With an allowance recorded	6	7
Consumer [Member] | Other Consumer [Member] | Originated Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	4	15
Unpaid principal, With no related allowance recorded	52	29
Average recorded Investment, With no related allowance recorded	10	16
Interest income Recognized, With no related allowance recorded		1
Recorded investment, With an allowance recorded	3	19
Unpaid principal, With an allowance recorded	3	19
Related allowance, With an allowance recorded	3	13
Average recorded Investment, With an allowance recorded	10	9
Interest income Recognized, With an allowance recorded		2
Consumer [Member] | Other Consumer [Member] | PNCI Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded		3
Unpaid principal, With no related allowance recorded		4
Average recorded Investment, With no related allowance recorded	2	18
Recorded investment, With an allowance recorded	250	118
Unpaid principal, With an allowance recorded	250	118
Related allowance, With an allowance recorded	54	15
Average recorded Investment, With an allowance recorded	184	176
Interest income Recognized, With an allowance recorded	11	5
Consumer [Member] | Auto Indirect [Member] | Originated Loans [Member]
Financing Receivable, Impaired [Line Items]
Average recorded Investment, With no related allowance recorded		1
Consumer and Industrial [Member] | Originated Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	575	762
Unpaid principal, With no related allowance recorded	585	926
Average recorded Investment, With no related allowance recorded	668	669
Interest income Recognized, With no related allowance recorded	18	48
Recorded investment, With an allowance recorded	3,895	3,334
Unpaid principal, With an allowance recorded	3,981	3,385
Related allowance, With an allowance recorded	1,848	1,130
Average recorded Investment, With an allowance recorded	3,615	2,714
Interest income Recognized, With an allowance recorded	166	77
Consumer and Industrial [Member] | PNCI Loans [Member]
Financing Receivable, Impaired [Line Items]
Average recorded Investment, With no related allowance recorded		1
Construction [Member] | Residential [Member] | Originated Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	140	11
Unpaid principal, With no related allowance recorded	140	16
Average recorded Investment, With no related allowance recorded	76	7
Interest income Recognized, With no related allowance recorded	$ 9
Construction [Member] | Commercial [Member] | PNCI Loans [Member]
Financing Receivable, Impaired [Line Items]
Average recorded Investment, With no related allowance recorded		$ 245

Allowance for Loan Losses - Tro

Allowance for Loan Losses - Troubled Debt Restructurings (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)SecurityLoan	Dec. 31, 2016USD ($)SecurityLoan	Dec. 31, 2015USD ($)SecurityLoan
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan	26	24	23
Pre-mod outstanding principal balance	$ 7,111	$ 1,989	$ 3,979
Post-mod outstanding principal balance	6,978	2,035	3,973
Financial impact due to TDR taken as additional provision	$ 133	$ 326	$ 451
Number that defaulted during the period | SecurityLoan	5	3	10
Recorded investment of TDRs that subsequently defaulted during the 12 month period after modification	$ 624	$ 330	$ 736
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions	$ (5)		$ (9)
Mortgage Loans on Real Estate [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan	1	3	4
Pre-mod outstanding principal balance	$ 939	$ 650	$ 800
Post-mod outstanding principal balance	939	656	801
Financial impact due to TDR taken as additional provision	$ 169	$ 50	$ 8
Number that defaulted during the period | SecurityLoan	2	2	4
Recorded investment of TDRs that subsequently defaulted during the 12 month period after modification	$ 223	$ 101	$ 221
Mortgage Loans on Real Estate [Member] | Commercial [Member]
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan	8	5	5
Pre-mod outstanding principal balance	$ 3,721	$ 423	$ 1,518
Post-mod outstanding principal balance	3,695	461	1,517
Financial impact due to TDR taken as additional provision	$ (111)	$ 46	$ (5)
Number that defaulted during the period | SecurityLoan	1		2
Recorded investment of TDRs that subsequently defaulted during the 12 month period after modification	$ 219		$ 280
Consumer [Member] | Home Equity Lines of Credit [Member]
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan	3	9	2
Pre-mod outstanding principal balance	$ 187	$ 707	$ 301
Post-mod outstanding principal balance	187	709	$ 301
Financial impact due to TDR taken as additional provision	$ 27	$ 205
Number that defaulted during the period | SecurityLoan	1	1	3
Recorded investment of TDRs that subsequently defaulted during the 12 month period after modification	$ 127	$ 229	$ 182
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions	$ (5)
Consumer [Member] | Home Equity Loans [Member]
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan	1	1	2
Pre-mod outstanding principal balance	$ 252	$ 105	$ 315
Post-mod outstanding principal balance	$ 252	$ 105	321
Financial impact due to TDR taken as additional provision			$ 38
Number that defaulted during the period | SecurityLoan	1		1
Recorded investment of TDRs that subsequently defaulted during the 12 month period after modification	$ 55		$ 53
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions			$ (9)
Consumer [Member] | Other Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan	1	2	2
Pre-mod outstanding principal balance	$ 14	$ 27	$ 89
Post-mod outstanding principal balance	14	27	89
Financial impact due to TDR taken as additional provision	$ 11	$ 2	$ 5
Consumer and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan	11	4	8
Pre-mod outstanding principal balance	$ 1,854	$ 77	$ 956
Post-mod outstanding principal balance	1,747	77	944
Financial impact due to TDR taken as additional provision	$ 37	$ 23	$ 405
Construction [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan	1
Pre-mod outstanding principal balance	$ 144
Post-mod outstanding principal balance	$ 144

Foreclosed Assets - Summary of

Foreclosed Assets - Summary of Activity in Balance of Foreclosed Assets (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)Assets	Dec. 31, 2016USD ($)Assets	Dec. 31, 2015USD ($)
Schedule Of Foreclosed Assets Activity [Line Items]
Beginning balance, net	$ 3,986	$ 5,369
Additions/transfers from loans	1,563	2,505
Dispositions/sales	(2,161)	(3,748)
Valuation adjustments	(162)	(140)
Ending balance, net	3,226	3,986	$ 5,369
Ending valuation allowance	$ (200)	$ (314)
Ending number of foreclosed assets | Assets	16	15
Proceeds from sale of foreclosed assets	$ 2,872	$ 4,010
Gain on sale of foreclosed assets	711	262	991
Noncovered [Member]
Schedule Of Foreclosed Assets Activity [Line Items]
Beginning balance, net	3,763	5,369
Additions/transfers from loans	1,563	2,282
Dispositions/sales	(1,938)	(3,748)
Valuation adjustments	(162)	(140)
Ending balance, net	3,226	3,763	$ 5,369
Ending valuation allowance	$ (200)	$ (314)
Ending number of foreclosed assets | Assets	16	14
Proceeds from sale of foreclosed assets	$ 2,656	$ 4,010
Gain on sale of foreclosed assets	718	262
Covered [Member]
Schedule Of Foreclosed Assets Activity [Line Items]
Beginning balance, net	223
Additions/transfers from loans		223
Dispositions/sales	(223)
Ending balance, net		$ 223
Ending number of foreclosed assets | Assets		1
Proceeds from sale of foreclosed assets	216
Gain on sale of foreclosed assets	$ (7)

Foreclosed Assets - Additional

Foreclosed Assets - Additional Information (Detail) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule Of Foreclosed Assets Activity [Line Items]
Foreclosed assets	$ 3,226,000	$ 3,986,000	$ 5,369,000
Residential Real Estate [Member]
Schedule Of Foreclosed Assets Activity [Line Items]
Foreclosed assets	1,186,000
Formal foreclosure proceedings	$ 178,000

Premises and Equipment - Summar

Premises and Equipment - Summary of Premises and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment, Net, by Type [Abstract]
Land & land improvements	$ 9,959	$ 9,522
Buildings	50,340	42,345
Furniture and equipment	35,939	31,428
Premises and equipment, gross	96,238	83,295
Less: Accumulated depreciation	(40,644)	(37,412)
Premises and equipment less depreciation, gross	55,594	45,883
Construction in progress	2,148	2,523
Total premises and equipment	$ 57,742	$ 48,406

Premises and Equipment - Additi

Premises and Equipment - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Depreciation expense for premises and equipment	$ 5,686,000	$ 5,314,000	$ 5,043,000

Cash Value of Life Insurance -

Cash Value of Life Insurance - Summary of Activity in Balance of Cash Value of Life Insurance (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)PoliciesEmployeesCompany	Dec. 31, 2016USD ($)PoliciesEmployeesCompany	Dec. 31, 2015USD ($)
Increase (Decrease) in Insurance Liabilities [Abstract]
Beginning balance	$ 95,912	$ 94,560
Increase in cash value of life insurance	2,685	2,717	$ 2,786
Death benefit receivable in excess of cash value	108	238
Death benefit receivable	(922)	(1,603)
Ending balance	97,783	95,912	$ 94,560
End of period death benefit	$ 165,587	$ 165,669
Number of policies owned | Policies	182	185
Insurance companies used | Company	14	14
Current and former employees and directors covered | Employees	57	58

Cash Value of Life Insurance 89

Cash Value of Life Insurance - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017PoliciesCompany	Dec. 31, 2016Company
Insurance [Abstract]
Number of life insurance policies owned by the Company	182
Insurance companies used | Company	14	14
Policies covering current and former employees and directors	57

Goodwill and Other Intangible90

Goodwill and Other Intangible Assets - Summary of Goodwill Intangible (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, Ending Balance	$ 64,311
Goodwill, Additions	0
Goodwill, Reductions	0
Goodwill, Beginning Balance	$ 64,311

Goodwill and Other Intangible91

Goodwill and Other Intangible Assets - Summary of Core Deposit Intangibles (Detail) - Core Deposit Intangibles [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Finite-Lived Intangible Assets [Line Items]
Core deposit intangibles, Beginning balance	$ 10,120
Core deposit intangibles, Fully Depreciated	(562)
Core deposit intangibles, Reductions/Amortization	0
Core deposit intangibles, Additions	0
Core deposit intangibles, Ending balance	9,558
Accumulated amortization, Beginning balance	(3,557)
Accumulated amortization, Fully Depreciated	562
Accumulated amortization, Reductions/Amortization	(1,389)
Accumulated amortization, Additions	0
Accumulated amortization, Ending balance	(4,384)
Core deposit intangibles, net, Beginning balance	6,563
Core deposit intangibles, net, Fully Depreciated	0
Core deposit intangibles, net, Reductions/Amortization	(1,389)
Core deposit intangibles, net, Additions	0
Core deposit intangibles, net, Ending balance	$ 5,174

Goodwill and Other Intangible92

Goodwill and Other Intangible Assets - Additional Information (Detail)	Mar. 18, 2016USD ($)Branches	Oct. 03, 2014USD ($)	Sep. 23, 2011USD ($)	May 28, 2010USD ($)
North Valley Bancorp [Member]
Finite-Lived Intangible Assets [Line Items]
Additions to core deposit intangibles		$ 6,614,000
Citizens [Member]
Finite-Lived Intangible Assets [Line Items]
Additions to core deposit intangibles			$ 898,000
Granite [Member]
Finite-Lived Intangible Assets [Line Items]
Additions to core deposit intangibles				$ 562,000
Bank of America [Member]
Finite-Lived Intangible Assets [Line Items]
Additions to core deposit intangibles	$ 2,046,000
Number of branches | Branches	3

Goodwill and Other Intangible93

Goodwill and Other Intangible Assets - Remaining Estimated Core Deposit Intangible Amortization (Detail) - Core Deposit Intangibles [Member] $ in Thousands	Dec. 31, 2017USD ($)
Finite-Lived Intangible Assets [Line Items]
2,018	$ 1,324
2,019	1,228
2,020	1,228
2,021	969
2,022	280
Thereafter	$ 145

Mortgage Servicing Rights - Fai

Mortgage Servicing Rights - Fair Value of Mortgage Servicing Rights (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Servicing Assets at Fair Value [Line Items]
Contractually specified servicing fees, late fees and ancillary fees earned	$ 2,076	$ 2,065	$ 2,164
Weighted-average prepayment speed (CPR)	8.90%	8.80%	9.80%
Weighted-average discount rate	13.00%	14.00%	10.00%
Mortgage Servicing Rights [Member]
Servicing Assets at Fair Value [Line Items]
Balance at beginning of period	$ 6,595	$ 7,618	$ 7,378
Acquisition	0	0	0
Originations	810	1,161	941
Change in fair value	(718)	(2,184)	(701)
Balance at end of period	6,687	6,595	7,618
Loans [Member]
Servicing Assets at Fair Value [Line Items]
Balance at beginning of period	816,623	817,917	840,288
Balance at end of period	$ 811,065	$ 816,623	$ 817,917

Indemnification Asset - Summary

Indemnification Asset - Summary of Activity in Balance of Indemnification Asset (Liability) (Detail) - USD ($) $ in Thousands	May 09, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
FDIC Indemnification Asset [Roll Forward]
Beginning balance		$ (744)	$ (521)	$ (349)
Effect of actual covered losses (recoveries) and increase (decrease) in estimated future covered losses		(192)	(412)	(93)
Change in estimated "true up" liability		(32)	(86)	(71)
Reimbursable expenses, net			2	4
Payments made (received)	$ (184)	256	273	(12)
Gain on termination of loss share agreement	$ (712)	712
Ending balance			(744)	(521)
Amount of indemnification asset (liability) recorded in other assets			(60)	77
Amount of indemnification liability recorded in other liabilities			(684)	(598)
Ending balance		$ (744)	$ (521)	$ (349)

Indemnification Asset - Additio

Indemnification Asset - Additional Information (Detail) - USD ($) $ in Thousands	May 09, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fdic Agreements And Fdic Indemnification Asset [Line Items]
FDIC indemnification agreement expiry month and year		2020-05
Term of FDIC indemnification agreement		10 years
True up amount payable to FDIC, description		In addition, the agreement specified that at the end of the agreement in May 2020, to the extent that total claimed losses plus servicing expenses, net of recoveries, claimed under the agreement over the entire ten year period of the agreement did not meet a certain threshold, the Company would have been required to pay to the FDIC a “true up” amount equal to fifty percent of the difference of the threshold and actual claimed losses plus servicing expenses, net of recoveries. The Company continually estimated, updated and recorded this “true up” amount, at its estimated present value, since the inception of the agreement in May 2010.
Percentage of true up amount payable to FDIC		50.00%
Payment made to FDIC	$ 184	$ (256)	$ (273)	$ 12
Gain on termination of loss share agreement	$ 712	$ (712)
Residential Real Estate Loans [Member]
Fdic Agreements And Fdic Indemnification Asset [Line Items]
FDIC indemnification agreement expiry month and year		2018-05
Nonresidential Real Estate Loans [Member]
Fdic Agreements And Fdic Indemnification Asset [Line Items]
FDIC indemnification agreement expiry month and year		2010-05

Other Assets - Summary of Other

Other Assets - Summary of Other Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Deferred tax asset, net	$ 21,697	$ 36,199
Prepaid expense	4,111	3,045
Software	1,126	2,039
Advanced compensation	16	249
Capital Trusts	1,706	1,702
Investment in Low Housing Tax Credit Funds	16,854	18,465
Life insurance proceeds receivable	2,242	2,120
Prepaid Taxes	4,754	6,460
Premises held for sale		2,896
Miscellaneous other assets	2,545	1,568
Total other assets	$ 55,051	$ 74,743

Deposits - Summary of Balances

Deposits - Summary of Balances of Deposits (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deposits [Abstract]
Noninterest-bearing demand	$ 1,368,218	$ 1,275,745
Interest-bearing demand	971,459	887,625
Savings	1,364,518	1,397,036
Time certificates, over $250,000	73,596	75,184
Other time certificates	231,340	259,970
Total deposits	$ 4,009,131	$ 3,895,560

Deposits - Additional Informati

Deposits - Additional Information (Detail) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Deposits [Line Items]
Overdrawn deposit balances classified as consumer loans	$ 1,366,000	$ 1,191,000
California [Member]
Schedule Of Deposits [Line Items]
Certificate of deposits, included in time certificates $250,000 and over	$ 50,000,000	$ 50,000,000

Deposits - Schedule of Maturiti

Deposits - Schedule of Maturities of Time Deposits (Detail) $ in Thousands	Dec. 31, 2017USD ($)
Summary of maturities of time deposits [Abstract]
2,018	$ 0
2,019	250,277
2,020	23,577
2,021	17,699
2,020	8,887
Thereafter	4,496
Total	$ 304,936

Reserve for Unfunded Commitm101

Reserve for Unfunded Commitments - Summary of Activity in Reserve for Unfunded Commitments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Balance at beginning of period	$ 2,719	$ 2,475	$ 2,145
Change in reserve for unfunded commitments	445	244	330
Balance at end of period	$ 3,164	$ 2,719	$ 2,475

Other Liabilities - Components

Other Liabilities - Components of Other Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Other Liabilities Disclosure [Abstract]
Deferred compensation	$ 6,605	$ 6,525
Pension liability	28,472	26,645
Joint beneficiary agreements	3,365	3,007
Low income housing tax credit fund commitments	8,554	15,176
Accrued salaries and benefits expense	6,619	5,704
Loan escrow and servicing payable	1,958	2,146
Deferred revenue	1,228	726
Litigation contingency	1,450	1,450
Miscellaneous other liabilities	5,007	5,985
Total other liabilities	$ 63,258	$ 67,364

Other Borrowings - Summary of B

Other Borrowings - Summary of Balances of Other Borrowings (Detail) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Total other borrowings	$ 122,166,000	$ 17,493,000
1.38% Fixed Rate FHLB Collateralized Borrowings [Member]
Debt Instrument [Line Items]
Collateralized borrowing, fixed rate, as of December 31, 2017 of 1.38% & 0.05%, payable on January 2, 2018	104,729,000
0.05% Fixed Rate Collateralized Borrowings [Member]
Debt Instrument [Line Items]
Collateralized borrowing, fixed rate, as of December 31, 2017 of 1.38% & 0.05%, payable on January 2, 2018	$ 17,437,000	$ 17,493,000

Other Borrowings - Summary o104

Other Borrowings - Summary of Balances of Other Borrowings (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2017
1.38% Fixed Rate FHLB Collateralized Borrowings [Member]
Debt Instrument [Line Items]
Collateralized borrowing, fixed rate	1.38%
Collateralized borrowing, maturity date	Jan. 2, 2018
0.05% Fixed Rate Collateralized Borrowings [Member]
Debt Instrument [Line Items]
Collateralized borrowing, fixed rate	0.05%
Collateralized borrowing, maturity date	Jan. 2, 2018

Other Borrowings - Additional I

Other Borrowings - Additional Information (Detail) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Borrowings [Line Items]
Security repurchase agreement	$ 0	$ 0
FHLB collateral line of credit, maximum borrowings capacity	1,365,325,000
FHLB collateral line of credit, outstanding balance	104,729,000
FHLB collateral line of credit, remaining borrowing capacity	1,260,596,000
Loans designated as potential collateral under collateralized line of credit with FHLB	67,325,000
Investment securities designated as potential collateral under collateral line of credit	1,992,980,000
Repurchase investment securities sold and pledged as collateral under securities repurchase agreement	33,531,000
Collateralized line of credit with San Francisco Federal Reserve Bank, maximum borrowings capacity	134,660,000
Collateralized line of credit with San Francisco Federal Reserve Bank, outstanding balance	0
Collateralized line of credit with San Francisco Federal Reserve Bank, remaining borrowing capacity	134,660,000
Investment securities designated as potential collateral under collateral line of credit with San Francisco Federal Reserve Bank	17,000
Loans designated as potential collateral under collateral line of credit with San Francisco Federal Reserve Bank	245,532,000
Unused correspondent banking lines of credit from commercial banks for federal funds	20,000,000
0.05% Fixed Rate Collateralized Borrowings [Member]
Schedule Of Borrowings [Line Items]
Other collateralized borrowings	$ 17,437,000	$ 17,493,000

Junior Subordinated Debt - Addi

Junior Subordinated Debt - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017USD ($)LocationTrust	Dec. 31, 2016USD ($)	Oct. 03, 2014USD ($)
Class of Stock [Line Items]
Number of subsidiary business trusts | Trust	5
Trust preferred securities amount	$ 62,900,000
Subordinated debenture, recorded fair value	$ 56,858,000	$ 56,667,000
Number of locations organized | Location	2
Maximum [Member]
Class of Stock [Line Items]
Consecutive payments of interest on debenture defer Period	5 years
North Valley Bancorp [Member]
Class of Stock [Line Items]
Number of locations acquired | Location	3
Acquisition, completion date	Oct. 3, 2014
North Valley Trust II [Member]
Class of Stock [Line Items]
Subordinated debenture, recorded fair value	$ 5,135,000		$ 5,006,000
North Valley Trust III [Member]
Class of Stock [Line Items]
Subordinated debenture, recorded fair value	4,041,000		3,918,000
North Valley Trust IV [Member]
Class of Stock [Line Items]
Subordinated debenture, recorded fair value	$ 6,444,000		$ 6,063,000

Junior Subordinated Debt - Summ

Junior Subordinated Debt - Summary of Terms and Recorded Balance of Subordinated Debenture (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Oct. 03, 2014
Subordinated Borrowing [Line Items]
Subordinated debenture, Face Value	$ 62,889,000
Subordinated debenture, Recorded Book Value	$ 56,858,000	$ 56,667,000
TriCo Capital Trust I [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Maturity Date	Oct. 7, 2033
Subordinated debenture, Face Value	$ 20,619,000
Subordinated debenture, Current Coupon Rate	4.41%
Subordinated debenture, Recorded Book Value	$ 20,619,000
TriCo Capital Trust II [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Maturity Date	Jul. 23, 2034
Subordinated debenture, Face Value	$ 20,619,000
Subordinated debenture, Current Coupon Rate	3.91%
Subordinated debenture, Recorded Book Value	$ 20,619,000
North Valley Trust II [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Maturity Date	Apr. 24, 2033
Subordinated debenture, Face Value	$ 6,186,000
Subordinated debenture, Current Coupon Rate	4.63%
Subordinated debenture, Recorded Book Value	$ 5,135,000		$ 5,006,000
North Valley Trust III [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Maturity Date	Apr. 24, 2034
Subordinated debenture, Face Value	$ 5,155,000
Subordinated debenture, Current Coupon Rate	4.16%
Subordinated debenture, Recorded Book Value	$ 4,041,000		3,918,000
North Valley Trust IV [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Maturity Date	Mar. 15, 2036
Subordinated debenture, Face Value	$ 10,310,000
Subordinated debenture, Current Coupon Rate	2.92%
Subordinated debenture, Recorded Book Value	$ 6,444,000		$ 6,063,000
LIBOR PLUS [Member] | TriCo Capital Trust I [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Coupon Rate	3.05%
LIBOR PLUS [Member] | TriCo Capital Trust II [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Coupon Rate	2.55%
LIBOR PLUS [Member] | North Valley Trust II [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Coupon Rate	3.25%
LIBOR PLUS [Member] | North Valley Trust III [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Coupon Rate	2.80%
LIBOR PLUS [Member] | North Valley Trust IV [Member]
Subordinated Borrowing [Line Items]
Subordinated debenture, Coupon Rate	1.33%

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017USD ($)site$ / sharesshares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)	Aug. 21, 2007shares
Conversion of Stock [Line Items]
Reserves to satisfy Federal regulatory requirements	$ 82,068,000	$ 78,183,000
Number of sites leased under non-cancelable operating leases | site	48
Rent expense under operating leases	$ 5,885,000	6,082,000	$ 6,241,000
Rent expense offset by rent income	$ 44,000	220,000	$ 217,000
Commitment expiration date	One year or less or other termination clauses and may require payment of a fee.
Letters of credit, issue period	One year or less
Overdraft privilege receivable criteria	All holders of such accounts who bring their accounts to a positive balance at least once every thirty days receive the overdraft privilege.
Cost of settlement	$ 1,469,000	1,450,000
Agreement approval date	Jan. 12, 2018
Litigation contingency	$ 1,450,000	$ 1,450,000
Class B common stock of Visa Inc. | shares	22,955,963	22,867,802		15,814,662
Conversion ratio	1.648265
Common Class B [Member]
Conversion of Stock [Line Items]
Class B common stock of Visa Inc. | shares	13,396
Common Class A [Member]
Conversion of Stock [Line Items]
The value of the Class A shares | $ / shares	$ 114.02
Value of unredeemed Class A equivalent shares	$ 2,518,000

Commitments and Contingencie109

Commitments and Contingencies - Future Minimum Commitments under Non-Cancelable Operating Leases with Initial or Remaining Terms of One Year or More (Detail) $ in Thousands	Dec. 31, 2017USD ($)
Leases [Abstract]
2,018	$ 3,278
2,019	2,499
2,020	1,847
2,021	1,488
2,022	757
Thereafter	798
Future minimum lease payments	$ 10,667

Commitments and Contingencie110

Commitments and Contingencies - Summary of Bank's Commitments and Contingent Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments to extend credit
Construction [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments to extend credit	187,097	97,399
RE Mortgage [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments to extend credit	66,267	42,184
Standby Letters of Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments to extend credit	13,075	12,763
Commercial [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments to extend credit	257,220	220,836
Consumer Loans [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments to extend credit	422,958	406,855
Deposit Account Overdraft Privilege [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments to extend credit	$ 98,260	$ 98,583

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Aug. 21, 2007
Class of Stock [Line Items]
Repurchase of common stock					500,000
Stock repurchase plan percentage of common stock					3.20%
Common stock, shares outstanding	22,955,963	22,867,802			15,814,662
Repurchased shares outstanding	166,600
Market value of common stock	$ 2,225,000	$ 5,988,000	$ 2,868,000
Maximum [Member]
Class of Stock [Line Items]
Cash dividend payable by bank	85,254,000
Tri Counties Bank [Member]
Class of Stock [Line Items]
Cash dividends received	$ 19,236,000	$ 16,758,000	$ 13,304,000
Stock Repurchase Plan [Member]
Class of Stock [Line Items]
Stock repurchase plan, number of shares repurchased	0
Common Stock [Member]
Class of Stock [Line Items]
Common stock, shares outstanding	22,955,963	22,867,802	22,775,173	22,714,964
Stock repurchase plan, number of shares repurchased	107,390	264,800	106,355
Company's common stock in lieu of cash to exercise options to purchase shares	107,390	264,800	106,355
Market value of common stock	$ 3,854,000	$ 7,879,000	$ 2,868,000

Stock Options and Other Equi112

Stock Options and Other Equity-Based Incentive Instruments - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding options under the plan	446,400	592,250
Options currently not exercisable yet expected to vest	24,300
Weighted-average remaining contractual term	8 months 12 days
Pre-tax compensation costs expected to recognize	$ 108,000
Restricted Stock Units (RSUs) [Member] | Service Condition Vesting RSUs [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of units outstanding expected to vest	68,457	68,450
Weighted-average remaining contractual term	1 year 2 months 12 days
Pre-tax compensation costs	$ 1,448,000
Number of units released	30,896
Restricted Stock Units (RSUs) [Member] | Market Plus Service Condition Vesting RSUs [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of units outstanding expected to vest	52,829	47,426
Weighted-average remaining contractual term	1 year 4 months 24 days
Pre-tax compensation costs	$ 724,000
Number of units released	18,805
Minimum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Maximum aggregate number of shares of TriCo's common stock issued	650,000
Minimum [Member] | Restricted Stock Units (RSUs) [Member] | Market Plus Service Condition Vesting RSUs [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of units released	0
Maximum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Maximum aggregate number of shares of TriCo's common stock issued	1,650,000
Maximum [Member] | Restricted Stock Units (RSUs) [Member] | Market Plus Service Condition Vesting RSUs [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of units released	79,243
2009 Plan [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of shares to be reduced pursuant to stock option for computation of available number of shares for issuance	1
Number of shares to be reduced pursuant to restricted stock award for computation of available number of shares for issuance	2
Outstanding options under the plan	411,900
Options available for grant under the plan	527,039
2009 Plan [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of units outstanding expected to vest	121,286
2001 Plan [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding options under the plan	34,500
Options available for grant under the plan	0
Share based compensation grant expiry period	10 years

Stock Options and Other Equi113

Stock Options and Other Equity-Based Incentive Instruments - Stock Option Activity (Detail)	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding, Number of Shares, beginning balance | shares	592,250
Options granted, Number of Shares | shares	0
Options exercised, Number of Shares | shares	(145,850)
Options forfeited, Number of Shares | shares	0
Options outstanding, Number of Shares, ending balance | shares	446,400
Options outstanding, Weighted Average Exercise Price, beginning balance	$ 17.12
Options granted, Weighted Average Exercise Price	0
Options exercised, Weighted Average Exercise Price	17.97
Options forfeited, Weighted Average Exercise Price	0
Options outstanding, Weighted Average Exercise Price, ending balance	16.84
Minimum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding, Option Price per Share, beginning balance	12.63
Options granted, Option Price per Share	0
Options exercised, Option Price per Share	14.54
Options forfeited, Option Price per Share	0
Options outstanding, Option Price per Share, ending balance	12.63
Maximum [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding, Option Price per Share, beginning balance	23.21
Options granted, Option Price per Share	0
Options exercised, Option Price per Share	22.54
Options forfeited, Option Price per Share	0
Options outstanding, Option Price per Share, ending balance	$ 23.21

Stock Options and Other Equi114

Stock Options and Other Equity-Based Incentive Instruments - Summary of Options Outstanding (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of options	446,400	592,250
Weighted average exercise price	$ 16.84	$ 17.12
Intrinsic value (in thousands)	$ 9,382
Weighted average remaining contractual term (yrs.)	3 years 10 months 25 days
Currently Exercisable [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of options	422,100
Weighted average exercise price	$ 16.65
Intrinsic value (in thousands)	$ 8,953
Weighted average remaining contractual term (yrs.)	3 years 9 months 18 days
Currently Not Exercisable [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of options	24,300
Weighted average exercise price	$ 20.21
Intrinsic value (in thousands)	$ 429
Weighted average remaining contractual term (yrs.)	5 years 8 months 12 days

Stock Options and Other Equi115

Stock Options and Other Equity-Based Incentive Instruments - Information about Options (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Information about Options
Intrinsic value of options exercised	$ 2,657,000	$ 3,483,000	$ 969,000
Fair value of options that vested	259,000	580,000	734,000
Total compensation costs for options recognized in income	259,000	580,000	734,000
Excess tax benefit recognized in income	109,000	$ 244,000	$ 380,000
ASU 2016-09 [Member]
Information about Options
Excess tax benefit recognized in income	$ 906,000

Stock Options and Other Equi116

Stock Options and Other Equity-Based Incentive Instruments - Restricted Stock Unit (RSU) Activity (Detail) - Restricted Stock Units (RSUs) [Member]	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Market Plus Service Condition Vesting RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs outstanding, Number of RSUs, beginning balance	47,426
RSUs granted, Number of RSUs	17,939
Additional market plus service condition RSUs vested	6,269
RSUs released, Number of RSUs	(18,805)
RSUs outstanding, Number of RSUs, ending balance	52,829
RSUs granted, Weighted Average Fair Value on Date of Grant | $ / shares	$ 32.95
Service Condition Vesting RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs outstanding, Number of RSUs, beginning balance	68,450
RSUs granted, Number of RSUs	29,669
RSUs added through dividend credits, Number of RSUs	1,245
RSUs released, Number of RSUs	(30,896)
RSUs forfeited/expired, Number of RSUs	(11)
RSUs outstanding, Number of RSUs, ending balance	68,457
RSUs granted, Weighted Average Fair Value on Date of Grant | $ / shares	$ 35.36

Stock Options and Other Equi117

Stock Options and Other Equity-Based Incentive Instruments - Summary of Compensation Costs for RSUs (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Service Condition Vesting RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation costs for RSUs recognized in income	$ 895,000	$ 616,000	$ 458,000
Market Plus Service Condition Vesting RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation costs for RSUs recognized in income	$ 432,000	$ 271,000	$ 179,000

Noninterest Income and Expen118

Noninterest Income and Expense - Components of Other Noninterest Income (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Service charges on deposit accounts									$ 16,056	$ 14,365	$ 14,276
ATM and interchange fees									16,727	15,859	13,364
Other service fees									3,282	3,121	2,977
Mortgage banking service fees									2,076	2,065	2,164
Change in value of mortgage servicing rights									(718)	(2,184)	(701)
Total service charges and fees									37,423	33,226	32,080
Gain on sale of loans									3,109	4,037	3,064
Commissions on sale of non-deposit investment products									2,729	2,329	3,349
Increase in cash value of life insurance									2,685	2,717	2,786
Gain on sale of investments									961		0
Lease brokerage income									782	711	712
Gain on sale of foreclosed assets									711	262	991
Change in indemnification asset									490	(493)	(207)
Sale of customer checks									372	408	492
Life insurance benefit in excess of cash value									108	238	155
Loss on disposal of fixed assets									(142)	(147)	(129)
Other									793	1,275	2,054
Total other noninterest income									12,598	11,337	13,267
Total noninterest income	$ 12,478	$ 12,930	$ 12,910	$ 11,703	$ 12,462	$ 11,066	$ 11,245	$ 9,790	$ 50,021	$ 44,563	$ 45,347

Noninterest Income and Expen119

Noninterest Income and Expense - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Mortgage loan servicing fees, net of change in fair value of mortgage loan servicing rights	$ 1,358,000	$ (119,000)	$ 1,463,000

Noninterest Income and Expen120

Noninterest Income and Expense - Components of Noninterest Expense (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule Of Other Noninterest Income And Expense [Line Items]
Base salaries, net of deferred loan origination costs									$ 54,589	$ 53,169	$ 46,822
Incentive compensation									9,227	8,872	6,964
Benefits and other compensation costs									19,114	18,683	17,619
Total salaries and benefits expense									82,930	80,724	71,405
Occupancy									10,894	10,139	10,126
Data processing and software									10,448	8,846	7,670
Equipment									7,141	6,597	5,997
ATM & POS network charges									4,752	4,999	4,190
Advertising									4,101	3,829	3,992
Professional fees									3,745	5,409	4,545
Telecommunications									2,713	2,749	3,007
Assessments									1,676	2,105	2,572
Operational losses									1,394	1,564	737
Intangible amortization									1,389	1,377	1,157
Postage									1,296	1,603	1,296
Courier service									1,035	998	1,154
Change in reserve for unfunded commitments									445	244	330
Foreclosed assets expense									231	266	490
Provision for foreclosed asset losses									162	140	502
Legal settlement									1,469	1,450
Merger & acquisition expense									530	784	586
Miscellaneous other									12,142	12,174	11,085
Total other noninterest expense									64,094	65,273	59,436
Total noninterest expense	$ 38,076	$ 37,222	$ 35,904	$ 35,822	$ 36,563	$ 37,416	$ 38,267	$ 33,751	147,024	145,997	130,841
Total merger expense									530	784	586
North Valley Bancorp [Member]
Schedule Of Other Noninterest Income And Expense [Line Items]
Base salaries, net of loan origination costs										187
Data processing and software											108
Professional fees									513	342	120
Miscellaneous other									$ 17	$ 255	$ 358

Income Taxes - Components of Co

Income Taxes - Components of Consolidated Income Tax Expense (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current tax expense
Federal									$ 17,835	$ 17,401	$ 21,076
State									6,650	7,121	7,139
Current tax expense, Total									24,485	24,522	28,215
Deferred tax expense
Federal									11,418	2,735	408
State									1,055	455	273
Deferred tax benefit, Total									12,473	3,190	681
Total tax expense	$ 14,829	$ 7,130	$ 7,647	$ 7,352	$ 7,954	$ 7,694	$ 5,506	$ 6,558	$ 36,958	$ 27,712	$ 28,896

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes (Textual) [Abstract]
Federal corporate tax rate		35.00%	35.00%	35.00%
Deferred tax expense		$ 7,416,000
Amortization expense on the low income housing tax credit		226,000
Taxes relating to changes in unfunded status of the supplemental retirement plans		(400,000)	$ (429,000)	$ (904,000)
Taxes (benefits) related to unrealized gains and losses on available-for-sale investment securities		2,722,000	(4,631,000)	(797,000)
Taxes (benefits) related to employee stock options		0	(170,000)	$ (28,000)
Carrying value of low income housing tax credit funds		16,854,000	18,465,000
Low income housing tax credit fund commitments		8,554,000	15,176,000
Unrecognized tax benefit		60,000	114,000
Interest		0	0
Penalties		0	$ 0
Scenario, Forecast [Member]
Income Taxes (Textual) [Abstract]
Federal corporate tax rate	21.00%
North Valley Bancorp [Member]
Income Taxes (Textual) [Abstract]
Unrecognized tax benefits, if recognized		60,000
Unrecognized tax benefit		34,000
Federal [Member]
Income Taxes (Textual) [Abstract]
Tax credit carryforwards		69,000
California [Member]
Income Taxes (Textual) [Abstract]
Net operating loss carryforwards		21,400,000
Tax credit carryforwards		$ 648,000

Income Taxes - Schedule of Comp

Income Taxes - Schedule of Components of Investments in Qualified Affordable Housing Projects (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Tax credits and other tax benefits - decrease in tax expense	$ (1,753)	$ (954)	$ (354)
Amortization - increase in tax expense	$ 1,611	$ 757	$ 277

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Effective Tax Rate and Statutory Federal Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Federal statutory income tax rate	35.00%	35.00%	35.00%
State income taxes, net of federal tax benefit	6.90%	6.80%	6.60%
Tax Cuts and Jobs Act impact on deferred re-measurement	9.60%
Tax-exempt interest on municipal obligations	(1.90%)	(1.80%)	(0.70%)
Tax-exempt life insurance related income	(1.30%)	(1.30%)	(1.30%)
Equity compensation	(1.20%)
Low income housing tax credit benefits	(2.30%)	(1.30%)	(0.40%)
Low income housing tax credit amortization	2.10%	0.80%
Non-deductible joint beneficiary agreement expense	0.10%	0.10%	0.10%
Non-deductible merger expense	0.20%
Other	0.50%	(0.10%)	0.40%
Effective Tax Rate	47.70%	38.20%	39.70%

Income Taxes - Company's Net De

Income Taxes - Company's Net Deferred Tax Asset Recorded in Other Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Allowance for losses and reserve for unfunded commitments	$ 9,900	$ 14,809
Deferred compensation	1,953	2,743
Accrued pension liability	6,835	9,220
Accrued bonus	171	1,727
Other accrued expenses	522	781
Unfunded status of the supplemental retirement plans	1,582	1,982
State taxes	1,397	2,257
Share based compensation	1,322	2,063
Nonaccrual interest	282	408
OREO write downs	59	132
Indemnification asset		313
Acquisition cost basis	2,187	3,996
Unrealized loss on securities	1,008	3,730
Tax credits	581	491
Net operating loss carryforwards	1,801	3,354
Other	508	981
Total deferred tax assets	30,108	48,987
Deferred tax liabilities:
Securities income	(958)	(1,362)
Depreciation	(1,987)	(3,032)
Merger related fixed asset valuations	(30)	(54)
Securities accretion	(315)	(478)
Mortgage servicing rights valuation	(1,943)	(2,710)
Core deposit intangible	(916)	(1,813)
Junior subordinated debt	(1,783)	(2,616)
Prepaid expenses and other	(479)	(723)
Total deferred tax liability	(8,411)	(12,788)
Net deferred tax asset	$ 21,697	$ 36,199

Income Taxes - Summary of Chang

Income Taxes - Summary of Changes in Unrecognized Tax Benefit (Including Interest and Penalties) (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Income Tax Disclosure [Abstract]
UTB, Beginning Balance	$ 114
UTB, Lapse of the applicable statute of limitations	(54)
UTB, Ending Balance	60
Interest/Penalties, Beginning Balance	7
Interest/Penalties, Lapse of the applicable statute of limitations	(5)
Interest/Penalties, Ending Balance	2
Total, Beginning Balance	121
Total, Lapse of the applicable statute of limitations	(59)
Total, Ending Balance	$ 62

Earnings Per Share - Computatio

Earnings Per Share - Computation of Earnings Per Share (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net income	$ 2,989	$ 11,897	$ 13,589	$ 12,079	$ 12,533	$ 12,199	$ 9,405	$ 10,674	$ 40,554	$ 44,811	$ 43,818
Average number of common shares outstanding									22,912	22,814	22,750
Effect of dilutive stock options									338	273	248
Average number of common shares outstanding used to calculate diluted earnings per share									23,250	23,087	22,998

Earnings per Share - Additional

Earnings per Share - Additional Information (Detail) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Options and restricted stock units excluded from diluted earnings per share because the effect of these options and restricted stock units was antidilutive	0	13,825	20,625

Comprehensive Income - Componen

Comprehensive Income - Components of Other Comprehensive Income and Related Tax Effects (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity [Abstract]
Unrealized holding losses on available for sale securities before reclassifications	$ 6,422	$ (11,015)	$ (1,895)
Amounts reclassified out of accumulated other comprehensive income	(961)
Unrealized holding losses on available for sale securities after reclassifications	5,461	(11,015)	(1,895)
Tax effect	(2,296)	4,631	797
Unrealized holding losses on available for sale securities, net of tax	3,165	(6,384)	(1,098)
Change in unfunded status of the supplemental retirement plans before reclassifications	(1,016)	511	1,384
Amounts reclassified out of accumulated other comprehensive income:
Amortization of prior service cost	(12)	(40)	(57)
Amortization of actuarial losses	390	550	823
Total amounts reclassified out of accumulated other comprehensive income	378	510	766
Change in unfunded status of the supplemental retirement plans after reclassifications	(638)	1,021	2,150
Tax effect	268	(429)	(904)
Change in unfunded status of the supplemental retirement plans, net of tax	(370)	592	1,246
Change in joint beneficiary agreement liability before reclassifications	(110)	(343)	277
Amounts reclassified out of accumulated other comprehensive income	0	0	0
Change in joint beneficiary agreement liability after reclassifications	(110)	(343)	277
Tax effect	0	0	0
Change in joint beneficiary agreement liability, net of tax	(110)	(343)	277
Total other comprehensive income (loss)	$ 2,685	$ (6,135)	$ 425

Comprehensive Income - Compo130

Comprehensive Income - Components of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	$ (5,228)	$ (7,913)
Net Unrealized Loss on Available For Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss, before tax	(3,409)	(8,870)
Accumulated other comprehensive loss, tax effect	1,008	3,729
Accumulated other comprehensive loss	(2,401)	(5,141)
Unfunded Status of Supplemental Retirement Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss, before tax	(5,352)	(4,714)
Accumulated other comprehensive loss, tax effect	2,250	1,982
Accumulated other comprehensive loss	(3,102)	(2,732)
Joint Beneficiary Agreement Liability [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss, before tax	(150)	(40)
Accumulated other comprehensive loss	$ (150)	$ (40)

Retirement Plans - Additional I

Retirement Plans - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Salaries & benefits expense	$ 82,930,000	$ 80,724,000	$ 71,405,000
Employee service period under ESOP	1 year
Contribution and paid out as benefits under ESOP	$ 2,073,000	1,368,000	2,651,000
Deferred compensation obligations	6,605,000	6,525,000
Earnings credits on deferred balances included in noninterest expense	478,000	487,000	538,000
Cash values of the insurance policies purchased to fund deferred compensation obligations	97,783,000	95,912,000	94,560,000
Unfunded status of the supplemental retirement plans	(5,352,000)	(4,714,000)
Net actuarial loss	509,000
Salaries and Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Expenses related to ESOP	$ 2,149,000	1,831,000	2,282,000
401(k) Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Minimum age for employees	21 years
Minimum period for employees to participate	90 days
Discretionary matching contribution equal to percentage of participant's contribution	50.00%
Discretionary matching contribution maximum percentage of eligible compensation	4.00%
Salaries & benefits expense	$ 776,000	678,000	300,000
Employer's contribution to retirement plan	767,000	811,000	$ 0
Supplemental Retirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Cash values of the insurance policies purchased to fund deferred compensation obligations	97,783,000	95,912,000
Unfunded status of the supplemental retirement plans	5,352,000	4,714,000
Accumulated other comprehensive loss	3,102,000	2,732,000
Deferred tax asset	$ 2,250,000	$ 1,982,000

Retirement Plans - Defined Bene

Retirement Plans - Defined Benefit Pension Plans (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Transition obligation	$ 4	$ 7
Prior service cost	(248)	(75)
Net actuarial loss	5,596	4,782
Amount included in accumulated other comprehensive loss	5,352	4,714
Deferred tax benefit	(2,250)	(1,982)
Amount included in accumulated other comprehensive loss, net of tax	$ 3,102	$ 2,732

Retirement Plans - Information

Retirement Plans - Information Pertaining to Activity in Supplemental Retirement Plans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in benefit obligation:
Benefit obligation at beginning of year	$ (26,645)	$ (26,184)
Acquisition	0	0
Service cost	(941)	(1,042)	$ (1,023)
Interest cost	(991)	(1,025)	(957)
Actuarial (loss)/gain	(1,203)	511
Plan amendments	185
Benefits paid	1,123	1,095
Benefit obligation at end of year	(28,472)	(26,645)	(26,184)
Change in plan assets:
Fair value of plan assets at beginning of year	0	0
Fair value of plan assets at end of year	0	0	$ 0
Funded status	(28,472)	(26,645)
Unrecognized net obligation existing at January 1, 1986	4	7
Unrecognized net actuarial loss	5,596	4,782
Unrecognized prior service cost	(248)	(75)
Accumulated other comprehensive income	(5,352)	(4,714)
Accrued benefit cost	(28,472)	(26,645)
Accumulated benefit obligation	$ (26,432)	$ (25,241)

Retirement Plans - Net Periodic

Retirement Plans - Net Periodic Benefit Cost Recognized for Supplemental Retirement Plans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net pension cost included the following components:
Service cost-benefits earned during the period	$ 941	$ 1,042	$ 1,023
Interest cost on projected benefit obligation	991	1,025	957
Amortization of net obligation at transition	2	2	2
Amortization of prior service cost	(12)	(41)	(57)
Recognized net actuarial loss	390	549	823
Net periodic pension cost	$ 2,312	$ 2,577	$ 2,748

Retirement Plans - Assumptions

Retirement Plans - Assumptions Used in Accounting for Plans (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Discount rate used to calculate benefit obligation	3.40%	3.80%	4.00%
Discount rate used to calculate net periodic pension cost	3.84%	4.00%	3.65%
Executive Compensation [Member]
Defined Benefit Plan Disclosure [Line Items]
Average annual increase in compensation	3.25%	2.50%	2.50%
Director Compensation [Member]
Defined Benefit Plan Disclosure [Line Items]
Average annual increase in compensation	0.00%	2.50%	2.50%

Retirement Plans - Expected Ben

Retirement Plans - Expected Benefit Payments to Participants and Estimated Contributions to be Made by Company (Detail) $ in Thousands	Dec. 31, 2017USD ($)
Retirement Benefits [Abstract]
Expected Benefit Payments to Participants, 2018	$ 1,106
Expected Benefit Payments to Participants, 2019	1,067
Expected Benefit Payments to Participants, 2020	1,233
Expected Benefit Payments to Participants, 2021	1,859
Expected Benefit Payments to Participants, 2022	2,008
Expected Benefit Payments to Participants, 2023-2027	10,169
Estimated Company Contributions, 2018	1,106
Estimated Company Contributions, 2019	1,067
Estimated Company Contributions, 2020	1,233
Estimated Company Contributions, 2021	1,859
Estimated Company Contributions, 2022	2,008
Estimated Company Contributions, 2023-2027	$ 10,169

Related Party Transactions - Su

Related Party Transactions - Summary of Activity in Lending Transactions (Detail) - Directors and Officers [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Beginning balance	$ 2,432	$ 4,201
Advances/new loans	437	730
Removed/payments	(721)	(2,499)
Ending balance	$ 2,148	$ 2,432

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Related Party Transactions [Abstract]
Bank deposits of directors, officers and other related parties	$ 46,025,000	$ 69,755,000

Fair Value Measurement - Record

Fair Value Measurement - Recorded Amount of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value Measurements on Recurring Basis [Member] - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	$ 737,570	$ 556,828
Obligations of U.S. Government Corporations and Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	604,789	429,678
Obligations of States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	123,156	117,617
Marketable Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	2,938	2,938
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	2,938	2,938
Level 1 [Member] | Marketable Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	2,938	2,938
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	727,945	547,295
Level 2 [Member] | Obligations of U.S. Government Corporations and Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	604,789	429,678
Level 2 [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	123,156	117,617
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	6,687	6,595
Mortgage Servicing Rights [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	6,687	6,595
Mortgage Servicing Rights [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	$ 6,687	$ 6,595

Fair Value Measurement - Additi

Fair Value Measurement - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfers between level 1 to level 2, Assets	$ 0	$ 0
Transfers between level 2 to level 1, Assets	0	0
Transfers between level 1 to level 2, Liabilities	0	0
Transfers between level 2 to level 1, Liabilities	0	0
Transfer into level 3	0	0
Transfer out of level 3	0	0
Carrying value of loans fully charged-off	0
Securities held to maturity	514,844,000	602,536,000
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities held to maturity	$ 0	$ 0

Fair Value Measurement - Reconc

Fair Value Measurement - Reconciliation of Assets and Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3) on Recurring Basis (Detail) - Mortgage Servicing Rights [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Ending Balance	$ 6,687	$ 6,595	$ 7,618
Transfers into (out of) Level 3	0	0	0
Change Included in Earnings	(718)	(2,184)	(701)
Issuances	810	1,161	941
Beginning Balance	$ 6,595	$ 7,618	$ 7,378

Fair Value Measurement - Quanti

Fair Value Measurement - Quantitative Information about Recurring Level 3 Fair Value Measurements (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Constant prepayment rate	8.90%	8.80%	9.80%
Discount rate	13.00%	14.00%	10.00%
Mortgage Servicing Rights [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortgages Servicing Rights, Fair Value	$ 6,687	$ 6,595	$ 7,618	$ 7,378
Minimum [Member] | Mortgage Servicing Rights [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate	13.00%	14.00%
Minimum [Member] | Mortgage Servicing Rights [Member] | Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Constant prepayment rate	6.20%	6.90%
Maximum [Member] | Mortgage Servicing Rights [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate	15.00%	16.00%
Maximum [Member] | Mortgage Servicing Rights [Member] | Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Constant prepayment rate	22.00%	16.60%
Weighted Average [Member] | Mortgage Servicing Rights [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate	13.00%	14.00%
Weighted Average [Member] | Mortgage Servicing Rights [Member] | Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Constant prepayment rate	8.90%	8.80%

Fair Value Measurement - Assets

Fair Value Measurement - Assets and Liabilities Measured at Fair Value on Nonrecurring Basis (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Impaired Originated & PNCI Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	$ 2,767	$ 1,107
Fair Value Nonrecurring Basis [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	4,984	3,360
Total Gains/(Losses)	(1,587)	(495)
Fair Value Nonrecurring Basis [Member] | Impaired Originated & PNCI Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	2,767	1,107
Total Gains/(Losses)	(1,452)	(409)
Fair Value Nonrecurring Basis [Member] | Foreclosed Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	2,217	2,253
Total Gains/(Losses)	(135)	(86)
Fair Value Nonrecurring Basis [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	4,984	3,360
Fair Value Nonrecurring Basis [Member] | Level 3 [Member] | Impaired Originated & PNCI Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	2,767	1,107
Fair Value Nonrecurring Basis [Member] | Level 3 [Member] | Foreclosed Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	$ 2,217	$ 2,253

Fair Value Measurement - Qua144

Fair Value Measurement - Quantitative Information about Level 3 Fair Value Measurements for Financial Instruments Measured at Fair Value on Nonrecurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Impaired Originated & PNCI Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 2,767	$ 1,107
Foreclosed Assets [Member] | Land & Construction [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	1,341	15
Foreclosed Assets [Member] | Residential Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	622	1,564
Foreclosed Assets [Member] | Commercial Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 254	$ 674

Fair Value Measurement - Estima

Fair Value Measurement - Estimated Fair Values of Financial Instruments that are Reported at Amortized Cost in Consolidated Balance Sheets (Detail) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Financial assets:
Cash and due from banks	$ 105,968,000	$ 92,197,000
Cash at Federal Reserve and other banks	99,460,000	213,415,000
Securities held to maturity	514,844,000	602,536,000
Financial liabilities:
Other borrowings	122,166,000	17,493,000
Junior subordinated debt	56,858,000	56,667,000
Level 3 [Member]
Financial assets:
Securities held to maturity	0	0
Level 3 [Member] | Overdraft Privilege Commitments [Member]
Off-balance sheet:
Contract amount, Off-balance sheet	98,260,000	98,583,000
Level 3 [Member] | Standby Letters of Credit [Member]
Off-balance sheet:
Contract amount, Off-balance sheet	13,075,000	12,763,000
Level 3 [Member] | Commitments [Member]
Off-balance sheet:
Contract amount, Off-balance sheet	933,542,000	767,274,000
Fair Value [Member] | Level 3 [Member]
Financial assets:
Loans, net	2,992,225,000	2,763,473,000
Financial liabilities:
Junior subordinated debt	58,466,000	49,033,000
Fair Value [Member] | Level 3 [Member] | Overdraft Privilege Commitments [Member]
Off-balance sheet:
Fair value, Off-balance sheet	983,000	986,000
Fair Value [Member] | Level 3 [Member] | Standby Letters of Credit [Member]
Off-balance sheet:
Fair value, Off-balance sheet	131,000	128,000
Fair Value [Member] | Level 3 [Member] | Commitments [Member]
Off-balance sheet:
Fair value, Off-balance sheet	9,335,000	7,673,000
Fair Value [Member] | Level 1 [Member]
Financial assets:
Cash and due from banks	105,968,000	92,197,000
Cash at Federal Reserve and other banks	99,460,000	213,415,000
Fair Value [Member] | Level 2 [Member]
Financial assets:
Securities held to maturity	518,165,000	603,203,000
Loans held for sale	4,616,000	2,998,000
Financial liabilities:
Deposits	4,006,620,000	3,893,941,000
Other borrowings	122,166,000	17,493,000
Carrying Amount [Member] | Level 3 [Member]
Financial assets:
Loans, net	2,984,842,000	2,727,090,000
Financial liabilities:
Junior subordinated debt	56,858,000	56,667,000
Carrying Amount [Member] | Level 1 [Member]
Financial assets:
Cash and due from banks	105,968,000	92,197,000
Cash at Federal Reserve and other banks	99,460,000	213,415,000
Carrying Amount [Member] | Level 2 [Member]
Financial assets:
Securities held to maturity	514,844,000	602,536,000
Restricted equity securities	16,956,000	16,596,000
Loans held for sale	4,616,000	2,998,000
Financial liabilities:
Deposits	4,009,131,000	3,895,560,000
Other borrowings	$ 122,166,000	$ 17,493,000

TriCo Bancshares Condensed F146

TriCo Bancshares Condensed Financial Statements (Parent Only) - Condensed Balance Sheets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets
Cash and Cash equivalents	$ 205,428	$ 305,612	$ 303,461	$ 610,728
Other assets	55,051	74,743
Total assets	4,761,315	4,517,968
Liabilities and shareholders' equity
Other liabilities	63,258	67,364
Junior subordinated debt	56,858	56,667
Total liabilities	4,255,507	4,040,621
Shareholders' equity:
Common stock, no par value: authorized 50,000,000 shares; issued and outstanding 22,955,963 and 22,867,802 shares, respectively	255,836	252,820
Retained earnings	255,200	232,440
Accumulated other comprehensive loss, net	(5,228)	(7,913)
Total shareholders' equity	505,808	477,347	452,116	418,172
Total liabilities and shareholders' equity	4,761,315	4,517,968
Parent [Member]
Assets
Cash and Cash equivalents	3,924	2,802	$ 2,565	$ 2,229
Investment in Tri Counties Bank	557,538	529,907
Other assets	1,721	1,711
Total assets	563,183	534,420
Liabilities and shareholders' equity
Other liabilities	517	406
Junior subordinated debt	56,858	56,667
Total liabilities	57,375	57,073
Shareholders' equity:
Common stock, no par value: authorized 50,000,000 shares; issued and outstanding 22,955,963 and 22,867,802 shares, respectively	255,836	252,820
Retained earnings	255,200	232,440
Accumulated other comprehensive loss, net	(5,228)	(7,913)
Total shareholders' equity	505,808	477,347
Total liabilities and shareholders' equity	$ 563,183	$ 534,420

TriCo Bancshares Condensed F147

TriCo Bancshares Condensed Financial Statements (Parent Only) - Condensed Balance Sheets (Parenthetical) (Detail) - $ / shares	Dec. 31, 2017	Dec. 31, 2016	Aug. 21, 2007
Condensed Financial Statements, Captions [Line Items]
Common stock, par value	$ 0	$ 0
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	22,955,963	22,867,802
Common stock, shares outstanding	22,955,963	22,867,802	15,814,662
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Common stock, par value	$ 0	$ 0
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	22,955,963	22,867,802
Common stock, shares outstanding	22,955,963	22,867,802

TriCo Bancshares Condensed F148

TriCo Bancshares Condensed Financial Statements (Parent Only) - Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Interest expense	$ (1,868)	$ (1,829)	$ (1,610)	$ (1,491)	$ (1,460)	$ (1,439)	$ (1,430)	$ (1,392)	$ (6,798)	$ (5,721)	$ (5,416)
Income before income taxes	17,818	19,027	21,236	19,431	20,487	19,893	14,911	17,232	77,512	72,523	72,714
Equity in net income of Tri Counties Bank:
Income tax benefit	(14,829)	(7,130)	(7,647)	(7,352)	(7,954)	(7,694)	(5,506)	(6,558)	(36,958)	(27,712)	(28,896)
Net income	$ 2,989	$ 11,897	$ 13,589	$ 12,079	$ 12,533	$ 12,199	$ 9,405	$ 10,674	40,554	44,811	43,818
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Interest expense									(2,535)	(2,229)	(1,977)
Administration expense									(915)	(725)	(814)
Income before income taxes									(3,450)	(2,954)	(2,791)
Equity in net income of Tri Counties Bank:
Distributed									19,236	16,758	13,304
Undistributed									23,359	29,764	32,131
Income tax benefit									1,409	1,243	1,174
Net income									$ 40,554	$ 44,811	$ 43,818

TriCo Bancshares Condensed F149

TriCo Bancshares Condensed Financial Statements (Parent Only) - Statements of Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Net income	$ 2,989	$ 11,897	$ 13,589	$ 12,079	$ 12,533	$ 12,199	$ 9,405	$ 10,674	$ 40,554	$ 44,811	$ 43,818
Other comprehensive income (loss), net of tax:
Unrealized holding gains (losses) on securities arising during the period									3,165	(6,384)	(1,098)
Change in minimum pension liability									(370)	592	1,246
Change in joint beneficiary agreement liability									(110)	(343)	277
Other comprehensive income (loss)									2,685	(6,135)	425
Comprehensive income									43,239	38,676	44,243
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Net income									40,554	44,811	43,818
Other comprehensive income (loss), net of tax:
Unrealized holding gains (losses) on securities arising during the period									3,165	(6,384)	(1,098)
Change in minimum pension liability									(370)	592	1,246
Change in joint beneficiary agreement liability									(110)	(343)	277
Other comprehensive income (loss)									2,685	(6,135)	425
Comprehensive income									$ 43,239	$ 38,676	$ 44,243

TriCo Bancshares Condensed F150

TriCo Bancshares Condensed Financial Statements (Parent Only) - Statements of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities:
Net income	$ 2,989	$ 11,897	$ 13,589	$ 12,079	$ 12,533	$ 12,199	$ 9,405	$ 10,674	$ 40,554	$ 44,811	$ 43,818
Adjustments to reconcile net income to net cash provided by operating activities:
Equity compensation vesting expense									1,586	1,467	1,370
Net cash from operating activities									55,381	48,226	54,817
Financing activities:
Equity compensation tax effect										155	(68)
Repurchase of common stock									(1,629)	(1,890)	(412)
Cash dividends paid - common									(15,131)	(13,695)	(11,849)
Net cash from financing activities									201,880	93,316	242,226
Net change in cash and cash equivalents									(100,184)	2,151	(307,267)
Cash and cash equivalents and beginning of year				305,612				303,461	305,612	303,461	610,728
Cash and cash equivalents at end of year	205,428				305,612				205,428	305,612	303,461
Parent [Member]
Operating activities:
Net income									40,554	44,811	43,818
Adjustments to reconcile net income to net cash provided by operating activities:
Undistributed equity in earnings of Tri Counties Bank									(23,359)	(29,764)	(32,131)
Equity compensation vesting expense									1,586	1,467	1,370
Equity compensation tax effect										(155)	68
Net change in other assets and liabilities									(1,295)	(1,210)	(1,120)
Net cash from operating activities									17,486	15,149	12,005
Financing activities:
Issuance of common stock through option exercise									396	518	660
Equity compensation tax effect										155	(68)
Repurchase of common stock									(1,629)	(1,890)	(412)
Cash dividends paid - common									(15,131)	(13,695)	(11,849)
Net cash from financing activities									(16,364)	(14,912)	(11,669)
Net change in cash and cash equivalents									1,122	237	336
Cash and cash equivalents and beginning of year				$ 2,802				$ 2,565	2,802	2,565	2,229
Cash and cash equivalents at end of year	$ 3,924				$ 2,802				$ 3,924	$ 2,802	$ 2,565

Regulatory Matters - Actual and

Regulatory Matters - Actual and Required Capital Ratios of Bank (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Tri Countries Bank [Member]
Schedule of Capitalization [Line Items]
Total Capital (to Risk Weighted Assets), Actual, Amount	$ 525,384	$ 500,876
Tier 1 Capital (to Risk Weighted Assets), Actual, Amount	491,897	465,654
Common Equity Tier 1 Capital (to Risk Weighted Assets), Actual, Amount	491,897	465,654
Tier 1 Capital (to Average Assets), Actual, Amount	$ 491,897	$ 465,654
Total Capital (to Risk Weighted Assets), Actual, Ratio	13.98%	14.71%
Tier 1 Capital (to Risk Weighted Assets), Actual, Ratio	13.09%	13.67%
Common Equity Tier 1 Capital (to Risk Weighted Assets), Actual, Ratio	13.09%	13.66%
Tier 1 Capital (to Average Assets), Actual, Ratio	10.73%	10.56%
Total Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 375,713	$ 340,529
Tier 1 Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	300,570	274,725
Common Equity Tier 1 Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	244,214	221,344
Tier 1 Capital (to Average Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 229,243	$ 220,426
Total Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	10.00%	10.00%
Tier 1 Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	8.00%	8.00%
Common Equity Tier 1 Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	6.50%	6.50%
Tier 1 Capital (to Average Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	5.00%	5.00%
Tri Countries Bank [Member] | Basel III Phase-in Schedule [Member]
Schedule of Capitalization [Line Items]
Total Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	$ 347,535	$ 293,706
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	272,392	225,601
Common Equity Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	216,035	174,521
Tier 1 Capital (to Average Assets), Minimum Capital Requirement, Amount	$ 183,394	$ 176,341
Total Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	9.25%	8.625%
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	7.25%	6.625%
Common Equity Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	5.75%	5.125%
Tier 1 Capital (to Average Assets), Minimum Capital Requirement, Ratio	4.00%	4.00%
Tri Countries Bank [Member] | Basel III Fully Phased In [Member]
Schedule of Capitalization [Line Items]
Total Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	$ 394,499	$ 357,556
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	319,356	289,450
Common Equity Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	262,999	238,370
Tier 1 Capital (to Average Assets), Minimum Capital Requirement, Amount	$ 183,394	$ 176,341
Total Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	10.50%	10.50%
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	8.50%	8.50%
Common Equity Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	7.00%	7.00%
Tier 1 Capital (to Average Assets), Minimum Capital Requirement, Ratio	4.00%	4.00%
Parent [Member]
Schedule of Capitalization [Line Items]
Total Capital (to Risk Weighted Assets), Actual, Amount	$ 528,805	$ 503,283
Tier 1 Capital (to Risk Weighted Assets), Actual, Amount	495,318	468,061
Common Equity Tier 1 Capital (to Risk Weighted Assets), Actual, Amount	440,643	414,632
Tier 1 Capital (to Average Assets), Actual, Amount	$ 495,318	$ 468,061
Total Capital (to Risk Weighted Assets), Actual, Ratio	14.07%	14.77%
Tier 1 Capital (to Risk Weighted Assets), Actual, Ratio	13.18%	13.74%
Common Equity Tier 1 Capital (to Risk Weighted Assets), Actual, Ratio	11.72%	12.17%
Tier 1 Capital (to Average Assets), Actual, Ratio	10.80%	10.62%
Parent [Member] | Basel III Phase-in Schedule [Member]
Schedule of Capitalization [Line Items]
Total Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	$ 347,694	$ 293,854
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	272,517	225,714
Common Equity Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	216,134	174,609
Tier 1 Capital (to Average Assets), Minimum Capital Requirement, Amount	$ 183,400	$ 176,346
Total Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	9.25%	8.625%
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	7.25%	6.625%
Common Equity Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	5.75%	5.125%
Tier 1 Capital (to Average Assets), Minimum Capital Requirement, Ratio	4.00%	4.00%
Parent [Member] | Basel III Fully Phased In [Member]
Schedule of Capitalization [Line Items]
Total Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	$ 394,679	$ 357,735
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	319,502	289,595
Common Equity Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	263,120	238,490
Tier 1 Capital (to Average Assets), Minimum Capital Requirement, Amount	$ 183,400	$ 176,346
Total Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	10.50%	10.50%
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	8.50%	8.50%
Common Equity Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	7.00%	7.00%
Tier 1 Capital (to Average Assets), Minimum Capital Requirement, Ratio	4.00%	4.00%

Regulatory Matters - Additional

Regulatory Matters - Additional Information (Detail)	Dec. 31, 2019	Dec. 31, 2017	Dec. 31, 2016
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Increase in risk-based capital ratios		0.625%
Capital conservation buffer ratio		1.25%	0.625%
Scenario, Forecast [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Minimum capital level requirements, Tier 1 capital ratio	8.50%
Minimum capital level requirements, Total capital ratio	10.50%
Scenario, Forecast [Member] | Common Stock [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Minimum capital level requirements, Tier 1 capital ratio	7.00%

Summary of Quarterly Results153

Summary of Quarterly Results of Operations (Unaudited) - Results of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Loans:
Discount accretion PCI - cash basis	$ 516	$ 398	$ 386	$ 112	$ 483	$ 777	$ 426	$ 269
Discount accretion PCI - other	445	407	797	631	658	569	415	(45)
Discount accretion PNCI	528	559	987	798	637	883	1,459	868
All other loan interest income	36,705	35,904	34,248	33,373	34,463	33,540	32,038	33,646
Total loan interest income	38,194	37,268	36,418	34,914	36,241	35,769	34,338	34,738	$ 146,794	$ 141,086	$ 131,836
Debt securities, dividends and interest bearing cash at Banks (not FTE)	8,767	8,645	8,626	8,570	8,374	7,940	8,252	8,056
Total interest and dividend income	46,961	45,913	45,044	43,484	44,615	43,709	42,590	42,794	181,402	173,708	161,414
Interest expense	1,868	1,829	1,610	1,491	1,460	1,439	1,430	1,392	6,798	5,721	5,416
Net interest income	45,093	44,084	43,434	41,993	43,155	42,270	41,160	41,402	174,604	167,987	155,998
(Benefit from reversal of) provision for loan losses	1,677	765	(796)	(1,557)	(1,433)	(3,973)	(773)	209	89	(5,970)	(2,210)
Net interest income after provision for loan losses	43,416	43,319	44,230	43,550	44,588	46,243	41,933	41,193	174,515	173,957	158,208
Noninterest income	12,478	12,930	12,910	11,703	12,462	11,066	11,245	9,790	50,021	44,563	45,347
Noninterest expense	38,076	37,222	35,904	35,822	36,563	37,416	38,267	33,751	147,024	145,997	130,841
Income before income taxes	17,818	19,027	21,236	19,431	20,487	19,893	14,911	17,232	77,512	72,523	72,714
Income tax expense	14,829	7,130	7,647	7,352	7,954	7,694	5,506	6,558	36,958	27,712	28,896
Net income	$ 2,989	$ 11,897	$ 13,589	$ 12,079	$ 12,533	$ 12,199	$ 9,405	$ 10,674	$ 40,554	$ 44,811	$ 43,818
Per common share:
Net income (diluted)	$ 0.13	$ 0.51	$ 0.58	$ 0.52	$ 0.54	$ 0.53	$ 0.41	$ 0.46	$ 1.74	$ 1.94	$ 1.91
Dividends	$ 0.17	$ 0.17	$ 0.17	$ 0.15	$ 0.15	$ 0.15	$ 0.15	$ 0.15	$ 0.66	$ 0.60	$ 0.52