TriCo Bancshares (TCBK) 10-Q 10 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	May 04, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Trading Symbol	TCBK
Entity Registrant Name	TRICO BANCSHARES /
Entity Central Index Key	356,171
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		22,969,792

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets:
Cash and due from banks	$ 87,138	$ 105,968
Cash at Federal Reserve and other banks	95,841	99,460
Cash and cash equivalents	182,979	205,428
Investment securities:
Marketable equity securities	2,890	2,938
Available for sale debt securities	735,895	727,945
Held to maturity debt securities	496,035	514,844
Restricted equity securities	16,956	16,956
Loans held for sale	2,149	4,616
Loans	3,069,733	3,015,165
Allowance for loan losses	(29,973)	(30,323)
Total loans, net	3,039,760	2,984,842
Foreclosed assets, net	1,564	3,226
Premises and equipment, net	58,558	57,742
Cash value of life insurance	98,391	97,783
Accrued interest receivable	12,407	13,772
Goodwill	64,311	64,311
Other intangible assets, net	4,835	5,174
Mortgage servicing rights	6,953	6,687
Other assets	56,274	55,051
Total assets	4,779,957	4,761,315
Deposits:
Noninterest-bearing demand	1,359,996	1,368,218
Interest-bearing	2,724,408	2,640,913
Total deposits	4,084,404	4,009,131
Accrued interest payable	958	930
Reserve for unfunded commitments	3,864	3,164
Other liabilities	63,529	63,258
Other borrowings	65,041	122,166
Junior subordinated debt	56,905	56,858
Total liabilities	4,274,701	4,255,507
Commitments and contingencies (Note 18)
Shareholders' equity:
Preferred stock, no par value: 1,000,000 shares authorized, zero issued and outstanding at March 31, 2018 and December 31, 2017
Common stock, no par value: 50,000,000 shares authorized; issued and outstanding: 22,956,323 at March 31, 2018 22,955,963 at December 31, 2017	256,226	255,836
Retained earnings	266,235	255,200
Accumulated other comprehensive loss, net of tax	(17,205)	(5,228)
Total shareholders' equity	505,256	505,808
Total liabilities and shareholders' equity	$ 4,779,957	$ 4,761,315

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2018	Dec. 31, 2017	Aug. 21, 2007
Statement of Financial Position [Abstract]
Preferred stock, no par value	$ 0	$ 0
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, no par value	$ 0	$ 0
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	22,956,323	22,955,963
Common stock, shares outstanding	22,956,323	22,955,963	15,814,662

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Interest and dividend income:
Loans, including fees	$ 38,049	$ 34,914
Investments:
Taxable securities	7,322	6,703
Tax exempt securities	1,041	1,041
Dividends	336	391
Interest bearing cash at Federal Reserve and other banks	373	435
Total interest and dividend income	47,121	43,484
Interest expense:
Deposits	1,096	894
Other borrowings	342	2
Junior subordinated debt	697	595
Total interest expense	2,135	1,491
Net interest income	44,986	41,993
Benefit from reversal of provision for loan losses	(236)	(1,557)
Net interest income after benefit from reversal of provision for loan losses	45,222	43,550
Noninterest income:
Service charges and fees	9,356	8,907
Gain on sale of loans	626	910
Commissions on sale of non-deposit investment products	876	607
Increase in cash value of life insurance	608	685
Other	824	594
Total noninterest income	12,290	11,703
Noninterest expense:
Salaries and related benefits	21,652	20,893
Other	16,510	14,929
Total noninterest expense	38,162	35,822
Income before income taxes	19,350	19,431
Provision for income taxes	5,440	7,352
Net income	$ 13,910	$ 12,079
Earnings per share:
Basic	$ 0.61	$ 0.53
Diluted	$ 0.60	$ 0.52

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 13,910	$ 2,989	$ 11,897	$ 13,589	$ 12,079
Other comprehensive income (loss), net of tax:
Unrealized gains (losses) on available for sale securities arising during the period	(11,026)				457
Change in minimum pension liability	80				54
Other comprehensive income (loss)	(10,946)				511
Comprehensive income	$ 2,964				$ 12,590

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, 2016	$ 477,347	$ 252,820	$ 232,440	$ (7,913)
Beginning balance, shares at Dec. 31, 2016		22,867,802
Net income	12,079		12,079
Other comprehensive income (loss)	511			511
Stock option vesting	88	$ 88
RSU vesting	204	204
PSU vesting	89	89
Stock options exercised	435	$ 435
Stock options exercised, shares		21,450
RSUs released	0	$ 0	0	0
RSUs released, shares		304
Repurchase of common stock, value	(604)	$ (180)	(424)
Repurchase of common stock, shares		(16,251)
Dividends paid	(3,431)		(3,431)
Ending balance at Mar. 31, 2017	486,718	$ 253,456	240,664	(7,402)
Ending balance, shares at Mar. 31, 2017		22,873,305
Beginning balance at Dec. 31, 2017	$ 505,808	$ 255,836	255,200	(5,228)
Beginning balance, shares at Dec. 31, 2017	22,955,963	22,955,963
Net income	$ 13,910		13,910
Adoption ASU | ASU 2016-01 [Member]			(62)	62
Adoption ASU | ASU 2018-02 [Member]			1,093	(1,093)
Other comprehensive income (loss)	(10,946)			(10,946)
Stock option vesting	37	$ 37
RSU vesting	238	238
PSU vesting	$ 116	116
Stock options exercised, shares	0
RSUs released	$ 0	$ 0	0	0
RSUs released, shares		494
Repurchase of common stock, value	(4)	$ (1)	(3)
Repurchase of common stock, shares		(134)
Dividends paid	(3,903)		(3,903)
Ending balance at Mar. 31, 2018	$ 505,256	$ 256,226	$ 266,235	$ (17,205)
Ending balance, shares at Mar. 31, 2018	22,956,323	22,956,323

Consolidated Statements of Cha7

Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Dividends paid, per share	$ 0.17	$ 0.15
Retained Earnings [Member]
Dividends paid, per share	$ 0.17	$ 0.15

Condensed Consolidated Stateme8

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating activities:
Net income	$ 13,910	$ 12,079
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of premises and equipment, and amortization	1,613	1,604
Amortization of intangible assets	339	359
Reversal of provision for loan losses	(236)	(1,557)
Amortization of investment securities premium, net	700	798
Originations of loans for resale	(20,332)	(34,317)
Proceeds from sale of loans originated for resale	23,270	36,771
Gain on sale of loans	(626)	(910)
Change in market value of mortgage servicing rights	(111)	13
Provision for (reversal of) losses on foreclosed assets	90	(66)
Gain on sale of foreclosed assets	(371)	(118)
Loss on disposal of fixed assets	13
Gain on sale of premises held for sale		(3)
Increase in cash value of life insurance	(608)	(685)
Gain on life insurance death benefit		(107)
Equity compensation vesting expense	391	381
Loss on marketable equity securities	48
Change in:
Reserve for unfunded commitments	700	15
Interest receivable	1,365	791
Interest payable	28	(48)
Other assets and liabilities, net	3,531	4,444
Net cash from operating activities	23,714	19,444
Investing activities:
Proceeds from maturities of securities available for sale	15,643	14,069
Proceeds from maturities of securities held to maturity	18,535	22,074
Purchases of securities available for sale	(39,647)	(35,241)
Loan origination and principal collections, net	(54,682)	(1,613)
Proceeds from sale of other real estate owned	1,943	726
Proceeds from sale of premises held for sale		3,338
Purchases of premises and equipment	(2,200)	(2,413)
Life insurance proceeds		282
Net cash provided by investing activities	(60,408)	1,222
Financing activities:
Net increase in deposits	75,273	3,324
Net change in other borrowings	(57,125)	(2,296)
Repurchase of common stock		(169)
Dividends paid	(3,903)	(3,431)
Net cash used by financing activities	14,245	(2,572)
Net change in cash and cash equivalents	(22,449)	18,094
Cash and cash equivalents and beginning of year	205,428	305,612
Cash and cash equivalents at end of year	182,979	323,706
Supplemental disclosure of noncash activities:
Unrealized (loss) gain on securities available for sale	(15,628)	787
Loans transferred to foreclosed assets		85
Deferred gain on sale of premises held for sale		438
Market value of shares tendered in-lieu of cash to pay for exercise of options and/or related taxes	4	604
Supplemental disclosure of cash flow activity:
Cash paid for interest expense	2,107	1,539
Cash paid for income taxes	$ 0	$ 0

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2018
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 and 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 consolidated 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 $1,703,000 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. The Company currently classifies all its operation into one business segment that it denotes as community banking. 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. Marketable Equity Securities As of December 31, 2017, marketable equity securities with a fair value of $2,938,000 were recorded within investment securities available for sale on the consolidated balance sheets with changes in the fair value recorded through other comprehensive income and accumulated other comprehensive income (loss). As of January 1, 2018, the Company adopted Accounting Standard Update (“ASU”) 2016-01 Debt Securities The Company classifies its debt 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. During the three months ended March 31, 2018 and throughout 2017, the Company did not have any debt 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. On May 9, 2017, the Company and the FDIC terminated their loss sharing agreements. 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 purchase 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 credits and other loans, standby letters of credits, and unused deposit account overdraft privilege. 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. Revenue Recognition The Company records revenue from contracts with customers in accordance with Accounting Standards Codification Topic 606, “Revenue from Contracts with Customers” (“Topic 606”). Under Topic 606, the Company must identify the contract with a customer, identify the performance obligations in the contract, determine the transaction price, allocate the transaction price to the performance obligations in the contract, and recognize revenue when (or as) the Company satisfies a performance obligation. Significant revenue has not been recognized in the current reporting period that results from performance obligations satisfied in previous periods. Most of our revenue-generating transactions are not subject to ASC 606, including revenue generated from financial instruments, such as our loans and investment securities. In addition, certain noninterest income streams such as fees associated with mortgage servicing rights, financial guarantees, derivatives, and certain credit card fees are also not in scope of the new guidance. The Company’s noninterest revenue streams are largely based on transactional activity, or standard month-end month-end 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 1st lien and 2nd lien non-owner occupied 1-4 residential real estate mortgage loans from commercial real estate mortgage loans to residential real estate mortgage loans and consumer home equity loans, respectively. This change in loan category classification was made to better align the Company’s financial reporting classifications with regulatory reporting classifications, and to properly classify these loans for regulatory risk-based capital ratio calculations. Certain amounts reported in previous consolidated financial statements have been reclassified and recalculated to conform to the presentation in this report. These reclassifications did not affect previously reported net income, total loans or total shareholders’ equity. 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 In January 2016, the FASB issued ASU No. 2016-01, “Recognition and Measurement of Financial Assets and Financial Liabilities.” available-for-sale No. 2016-01 Fair Value Measurement FASB issued Accounting Standard Update (ASU) No. 2016-02 , Leases (Topic 842) ASU 2016-2, on-balance ASU 2016-02 No. 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, 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 S

Business Combinations

Business Combinations	3 Months Ended
	Mar. 31, 2018
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. On March 21, 2018, the Company filed a registration statement on Form S-4 S-4

Investment Securities

Investment Securities	3 Months Ended
	Mar. 31, 2018
Investments Schedule [Abstract]
Investment Securities	Note 3—Investment Securities The amortized cost and estimated fair values of investments in debt securities are summarized in the following tables: March 31, 2018 Amortized Gross Gross Estimated (in thousands) Debt Securities Available for Sale Obligations of U.S. government corporations and agencies $ 633,310 $ 317 $ (16,970 ) $ 616,657 Obligations of states and political subdivisions 121,560 466 (2,788 ) 119,238 Total debt securities available for sale $ 754,870 $ 783 $ (19,758 ) $ 735,895 Debt Securities Held to Maturity Obligations of U.S. government corporations and agencies $ 481,457 $ 533 $ (7,737 ) $ 474,253 Obligations of states and political subdivisions 14,578 39 (231 ) 14,386 Total debt securities held to maturity $ 496,035 $ 572 $ (7,968 ) $ 488,639 December 31, 2017 Amortized Gross Gross Estimated (in thousands) Debt 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 Total debt securities available for sale $ 731,292 $ 2,583 $ (5,930 ) $ 727,945 Debt 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 debt securities held to maturity $ 514,844 $ 5,247 $ (1,926 ) $ 518,165 No investment securities were sold during the three months ended March 31, 2018 or the three months ended March 31, 2017. Investment securities with an aggregate carrying value of $415,542,000 and $285,596,000 at March 31, 2018 and December 31, 2017, 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 March 31, 2018 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 March 31, 2018, obligations of U.S. government corporations and agencies with a cost basis totaling $1,114,767,000 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 March 31, 2018, the Company estimates the average remaining life of these mortgage-backed securities issued by U.S. government corporations and agencies to be approximately 6.1 years. Average remaining life is defined as the time span after which the principal balance has been reduced by half. Debt Securities Available for Sale Held to Maturity (In thousands) Amortized Estimated Amortized Estimated Due in one year $ 2 $ 2 $ — $ — Due after one year through five years 235 236 1,215 1,228 Due after five years through ten years 3,324 3,452 20,631 20,291 Due after ten years 751,309 732,205 474,189 467,120 Totals $ 754,870 $ 735,895 $ 496,035 $ 488,639 Gross unrealized losses on debt 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 Fair Unrealized Fair Unrealized Fair Unrealized (in thousands) March 31, 2018 Debt Securities Available for Sale Obligations of U.S. government corporations and agencies $ 434,302 $ (10,345 ) $ 158,324 $ (6,625 ) $ 592,626 $ (16,970 ) Obligations of states and political subdivisions 65,047 (1,456 ) 16,042 (1,332 ) 81,089 (2,788 ) Total debt securities available for sale $ 499,349 $ (11,801 ) $ 174,366 $ (7,957 ) $ 673,715 $ (19,758 ) Debt Securities Held to Maturity Obligations of U.S. government corporations and agencies $ 299,575 $ (4,551 ) $ 89,809 $ (3,186 ) $ 389,384 $ (7,737 ) Obligations of states and political subdivisions 8,901 (144 ) 2,579 (87 ) 11,480 (231 ) Total debt securities held to maturity $ 308,476 $ (4,695 ) $ 92,388 $ (3,273 ) $ 400,864 $ (7,968 ) Less than 12 months 12 months or more Total Fair Unrealized Fair Unrealized Fair Unrealized (in thousands) December 31, 2017 Debt 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 ) Total securities available for sale $ 289,271 $ (2,211 ) $ 183,423 $ (3,719 ) $ 472,694 $ (5,930 ) Debt 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 debt securities held to maturity $ 94,505 $ (574 ) $ 98,004 $ (1,352 ) $ 192,509 $ (1,926 ) 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 March 31, 2018, 128 debt securities representing obligations of U.S. government corporations and agencies had unrealized losses with aggregate depreciation of (2.45%) 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 March 31, 2018, 94 debt securities representing obligations of states and political subdivisions had unrealized losses with aggregate depreciation of (3.16%) from the Company’s amortized cost basis. Marketable equity securities: All unrealized losses recognized during the reporting period were for equity securities still held at March 31, 2018.

Loans

Loans	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Loans	Note 4 — Loans A summary of loan balances follows (in thousands): March 31, 2018 Originated PNCI PCI - PCI - Total Mortgage loans on real estate: Residential 1-4 $ 323,161 $ 61,206 $ — $ 1,744 $ 386,111 Commercial 1,754,062 211,168 — 8,038 1,973,268 Total mortgage loan on real estate 2,077,223 272,374 — 9,782 2,359,379 Consumer: Home equity lines of credit 266,651 14,939 1,619 42 283,251 Home equity loans 38,889 2,558 — 485 41,932 Other 21,422 2,141 — 43 23,606 Total consumer loans 326,962 19,638 1,619 570 348,789 Commercial 205,673 7,837 — 2,505 216,015 Construction: Residential 71,589 9 — — 71,598 Commercial 73,701 251 — — 73,952 Total construction 145,290 260 — — 145,550 Total loans, net of deferred loan fees and discounts $ 2,755,148 $ 300,109 $ 1,619 $ 12,857 $ 3,069,733 Total principal balance of loans owed, net of charge-offs $ 2,764,819 $ 306,924 $ 5,167 $ 16,654 $ 3,093,564 Unamortized net deferred loan fees (9,671 ) — — — (9,671 ) Discounts to principal balance of loans owed, net of charge-offs — (6,815 ) (3,548 ) (3,797 ) (14,160 ) Total loans, net of unamortized deferred loan fees and discounts $ 2,755,148 $ 300,109 $ 1,619 $ 12,857 $ 3,069,733 Allowance for loan losses $ (29,057 ) $ (748 ) $ (8 ) $ (160 ) $ (29,973 ) 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 Allowance for loan losses $ (29,122 ) $ (929 ) $ (17 ) $ (255 ) $ (30,323 ) The following is a summary of the change in accretable yield for PCI – other loans during the periods indicated (in thousands): Three months ended March 31, 2018 2017 Change in accretable yield: Balance at beginning of period $ 4,262 $ 10,348 Accretion to interest income (255 ) (902 ) Reclassification (to) from nonaccretable difference 140 114 Balance at end of period $ 4,147 $ 9,560

Allowance for Loan Losses

Allowance for Loan Losses	3 Months Ended
	Mar. 31, 2018
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 – Three Months Ended March 31, 2018 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total Beginning balance $ 2,317 $ 11,441 $ 5,800 $ 1,841 $ 586 $ 6,512 $ 1,184 $ 642 $ 30,323 Charge-offs (1 ) — (80 ) — (194 ) (205 ) — — (480 ) Recoveries — 15 209 14 78 50 — — 366 (Benefit) provision (146 ) 39 (517 ) (119 ) 100 35 167 205 (236 ) Ending balance $ 2,170 $ 11,495 $ 5,412 $ 1,736 $ 570 $ 6,392 $ 1,351 $ 847 $ 29,973 Ending balance: Individ. evaluated for impairment $ 190 $ 154 $ 448 $ 130 $ 56 $ 2,113 — — $ 3,091 Loans pooled for evaluation $ 1,910 $ 11,281 $ 4,956 $ 1,606 $ 514 $ 4,249 $ 1,351 $ 847 $ 26,714 Loans acquired with deteriorated credit quality $ 70 $ 60 $ 8 — — $ 30 — — $ 168 Loans, net of unearned fees – As of March 31, 2018 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total Ending balance: Total loans $ 386,111 $ 1,973,268 $ 283,251 $ 41,932 $ 23,606 $ 216,015 $ 71,598 $ 73,952 $ 3,069,733 Individ. evaluated for impairment $ 5,535 $ 11,110 $ 2,450 $ 1,673 $ 278 $ 4,621 $ 136 — $ 25,803 Loans pooled for evaluation $ 378,832 $ 1,954,120 $ 279,140 $ 39,774 $ 23,285 $ 208,889 $ 71,462 $ 73,952 $ 3,029,454 Loans acquired with deteriorated credit quality $ 1,744 $ 8,038 $ 1,661 $ 485 $ 43 $ 2,505 — — $ 14,476 Allowance for Loan Losses—Year Ended December 31, 2017 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans 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 Other Construction (in thousands) Resid. Comm. Lines Loans 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 – Three Months Ended March 31, 2017 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans 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 — — (71 ) (31 ) (174 ) (133 ) — — (409 ) Recoveries — 110 46 12 141 170 — 1 480 (Benefit) provision (86 ) (85 ) (489 ) (174 ) 6 (542 ) (78 ) (109 ) (1,557 ) Ending balance $ 2,662 $ 11,542 $ 6,530 $ 2,451 $ 595 $ 5,326 $ 1,339 $ 572 $ 31,017 Ending balance: Individ. evaluated for impairment $ 249 $ 124 $ 400 $ 57 $ 31 $ 811 $ 14 — $ 1,686 Loans pooled for evaluation $ 2,188 $ 9,971 $ 6,122 $ 2,328 $ 564 $ 3,873 $ 1,282 $ 572 $ 26,900 Loans acquired with deteriorated credit quality $ 225 $ 1,447 $ 8 $ 66 — $ 642 $ 43 — $ 2,431 Loans, net of unearned fees – As of March 31, 2017 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total Ending balance: Total loans $ 309,701 $ 1,761,114 $ 283,596 $ 40,241 $ 29,313 $ 212,685 $ 59,699 $ 64,843 $ 2,761,192 Individ. evaluated for impairment $ 3,849 $ 16,979 $ 2,204 $ 1,241 $ 280 $ 3,072 $ 25 — $ 27,650 Loans pooled for evaluation $ 304,493 $ 1,731,785 $ 277,388 $ 37,867 $ 28,967 $ 205,832 $ 58,830 $ 64,843 $ 2,710,005 Loans acquired with deteriorated credit quality $ 1,359 $ 12,350 $ 4,004 $ 1,133 $ 66 $ 3,781 $ 844 — $ 23,537 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 March 31, 2018 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total Originated loans: Pass $ 317,799 $ 1,716,599 $ 263,270 $ 35,730 $ 21,067 $ 193,829 $ 71,482 $ 68,846 $ 2,688,622 Special mention 2,274 23,679 1,628 1,532 238 7,263 — 4,855 41,469 Substandard 3,088 13,784 1,753 1,627 117 4,581 107 — 25,057 Loss — — — — — — — — — Total originated $ 323,161 $ 1,754,062 $ 266,651 $ 38,889 $ 21,422 $ 205,673 $ 71,589 $ 73,701 $ 2,755,148 PNCI loans: Pass $ 59,184 $ 201,641 $ 13,686 $ 2,301 $ 2,067 $ 7,837 $ 9 $ 251 $ 286,976 Special mention 214 8,977 282 184 37 — — — 9,694 Substandard 1,808 550 971 73 37 — — — 3,439 Loss — — — — — — — — — Total PNCI $ 61,206 $ 211,168 $ 14,939 $ 2,558 $ 2,141 $ 7,837 $ 9 $ 251 $ 300,109 PCI loans $ 1,744 $ 8,038 $ 1,661 $ 485 $ 43 $ 2,505 — — $ 14,476 Total loans $ 386,111 $ 1,973,268 $ 283,251 $ 41,932 $ 23,606 $ 216,015 $ 71,598 $ 73,952 $ 3,069,733 Credit Quality Indicators – As of December 31, 2017 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans 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 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 March 31, 2018 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total Originated loan balance: Past due: 30-59 $ 2,217 $ 5,531 $ 938 $ 1,490 $ 63 $ 915 $ 298 $ — $ 11,452 60-89 — — 26 18 18 534 — 1,249 1,845 > 90 Days 846 1,162 320 154 — 1,557 — — 4,039 Total past due 3,063 6,693 1,284 1,662 81 3,006 298 1,249 17,336 Current 320,098 1,747,369 265,367 37,227 21,341 202,667 71,291 72,452 2,737,812 Total originated loans $ 323,161 $ 1,754,062 $ 266,651 $ 38,889 $ 21,422 $ 205,673 $ 71,589 $ 73,701 $ 2,755,148 > 90 Days and still accruing — — — — — — — — — Nonaccrual loans $ 2,235 $ 7,925 $ 733 $ 1,193 $ 4 $ 3,990 — — $ 16,080 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 March 31, 2018 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total PNCI loan balance: Past due: 30-59 $ 2,537 — $ 362 $ 2 — $ 1 — — $ 2,902 60-89 — — — — 4 — — — 4 > 90 Days — — 146 — 28 — — — 174 Total past due 2,537 — 508 2 32 1 — — 3,080 Current 58,669 211,168 14,431 2,556 2,109 7,836 9 251 297,029 Total PNCI loans $ 61,206 $ 211,168 $ 14,939 $ 2,558 $ 2,141 $ 7,837 $ 9 $ 251 $ 300,109 > 90 Days and still accruing — — — — — — — — — Nonaccrual loans $ 1,067 — $ 571 $ 40 $ 33 — — — $ 1,711 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 Other Construction (in thousands) Resid. Comm. Lines Loans 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 originated 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 Other Construction (in thousands) Resid. Comm. Lines Loans 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 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 original 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, or for the Three Months Ended, March 31, 2018 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total With no related allowance recorded: Recorded investment $ 2,678 $ 9,848 $ 888 $ 1,193 — $ 881 $ 136 — $ 15,624 Unpaid principal $ 2,829 $ 10,126 $ 944 $ 1,548 — $ 894 $ 136 — $ 16,477 Average recorded investment $ 2,368 $ 11,474 $ 991 $ 1,150 $ 2 $ 728 $ 138 — $ 16,851 Interest income recognized $ 19 $ 35 $ 6 — — $ 9 $ 2 — $ 71 With an allowance recorded: Recorded investment $ 1,525 $ 1,262 $ 527 $ 196 $ 4 $ 3,740 — — $ 7,254 Unpaid principal $ 1,549 $ 1,281 $ 534 $ 196 $ 4 $ 3,862 — — $ 7,426 Related allowance $ 190 $ 154 $ 146 $ 10 $ 4 $ 2,113 — — $ 2,617 Average recorded investment $ 1,703 $ 1,036 $ 464 $ 197 $ 4 $ 3,817 — — $ 7,221 Interest income recognized $ 9 $ 9 $ 4 $ 2 — $ 17 — — $ 41 Impaired PNCI Loans – As of, or for the Three Months Ended, March 31, 2018 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total With no related allowance recorded: Recorded investment $ 1,332 — $ 501 $ 40 $ 28 — — — $ 1,901 Unpaid principal $ 1,390 — $ 529 $ 54 $ 28 — — — $ 2,001 Average recorded investment $ 1,345 — $ 546 $ 42 $ 14 — — — $ 1,947 Interest income recognized $ 2 — $ 2 — — — — $ 4 With an allowance recorded: Recorded investment — — $ 534 $ 244 $ 246 — — — $ 1,024 Unpaid principal — — $ 536 $ 244 $ 246 — — — $ 1,026 Related allowance — — $ 302 $ 120 $ 52 — — — $ 474 Average recorded investment — — $ 568 $ 183 $ 248 — — — $ 999 Interest income recognized — — $ 3 $ 3 $ 2 — — — $ 8 Impaired Originated Loans – As of, or for the Twelve Months Ended, December 31, 2017 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans 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, or for the Twelve Months Ended, December 31, 2017 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans 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, or for the Three Months Ended, March 31, 2017 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total With no related allowance recorded: Recorded investment $ 1,782 $ 14,431 $ 1,064 $ 743 $ 5 $ 1,289 $ 11 — $ 19,325 Unpaid principal $ 1,793 $ 14,881 $ 1,144 $ 1,085 $ 6 $ 1,312 $ 16 — $ 20,237 Average recorded investment $ 2,834 $ 20,770 $ 2,013 $ 845 $ 12 $ 932 $ 7 — $ 27,413 Interest income recognized $ 20 $ 98 $ 6 $ 1 — $ 7 — — $ 132 With an allowance recorded: Recorded investment $ 1,378 $ 640 $ 427 $ 440 $ 21 $ 1,783 $ 14 — $ 4,703 Unpaid principal $ 1,382 $ 640 $ 440 $ 443 $ 22 $ 1,842 $ 14 — $ 4,783 Related allowance $ 172 $ 18 $ 106 $ 57 $ 14 $ 811 $ 14 — $ 1,192 Average recorded investment $ 1,692 $ 1,029 $ 1,076 $ 557 $ 11 $ 1,938 $ 7 — $ 6,310 Interest income recognized $ 11 $ 9 $ 1 $ 5 — $ 14 — — $ 40 Impaired PNCI Loans – As of, or for the Three Months Ended, March 31, 2017 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total With no related allowance recorded: Recorded investment $ 433 $ 1,777 $ 220 $ 58 $ 138 — — — $ 2,626 Unpaid principal $ 455 $ 2,011 $ 233 $ 67 $ 139 — — — $ 2,905 Average recorded investment $ 654 $ 1,455 $ 337 $ 64 $ 86 $ 1 — $ 245 $ 2,842 Interest income recognized $ 2 — $ 1 — $ 2 — — — $ 5 With an allowance recorded: Recorded investment $ 256 $ 131 $ 493 — $ 116 — — — $ 996 Unpaid principal $ 256 $ 131 $ 493 — $ 116 — — — $ 996 Related allowance $ 77 $ 106 $ 295 — $ 16 — — — $ 494 Average recorded investment $ 128 $ 1,440 $ 550 $ 19 $ 175 — — — $ 2,312 Interest income recognized $ 2 $ 2 $ 5 — $ 1 — — — $ 10 At March 31, 2018, $9,781,000 of originated loans were TDR and classified as impaired. The Company had obligations to lend $1,000 of additional funds on these TDR as of March 31, 2018. At March 31, 2018, $1,471,000 of PNCI loans were TDR and classified as impaired. The Company had no obligations to lend additional funds on these TDR as of March 31, 2018. 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 March 31, 2017, $12,285,000 of originated loans were TDR and classified as impaired. The Company had obligations to lend $70,000 of additional funds on these TDR as of March 31, 2017. At March 31, 2017, $1,470,000 of PNCI loans were TDR and classified as impaired. The Company had no obligations to lend additional funds on these TDR as of March 31, 2017. The following table shows certain information regarding TDRs that occurred during the period indicated: TDR Information for the Three Months Ended March 31, 2018 RE Mortgage Home Equity Other Construction (dollars in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total Number — 1 1 1 — — — — 3 Pre-mod — $ 384 $ 133 $ 121 — — — — $ 638 Post-mod — $ 384 $ 138 $ 121 — — — — $ 643 Financial impact due to TDR taken as additional provision — $ 11 — — — — — — $ 11 Number that defaulted during the period — 1 — — — — — — 1 Recorded investment of TDRs that defaulted during the period — $ 169 — — — — — — $ 169 Financial impact due to the default of previous TDR taken as charge-offs or additional provisions — — — — — — — — — The following table shows certain information regarding TDRs that occurred during the period indicated: TDR Information for the Year Ended December 31, 2017 RE Mortgage Home Equity Other Construction (dollars in thousands) Resid. Comm. Lines Loans 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 defaulted during the period $ 223 $ 219 $ 127 $ 55 — — — — $ 624 Financial impact due to the default of previous TDR taken as charge-offs or additional provisions — — $ (5 ) — — — — — $ (5 ) Modifications classified as TDRs 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 TDRs, 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	3 Months Ended
	Mar. 31, 2018
Text Block [Abstract]
Foreclosed Assets	Note 6 – Foreclosed Assets A summary of the activity in the balance of foreclosed assets follows (dollars in thousands): Three months ended Three months ended March 31, 2017 Total Noncovered Covered Total Beginning balance, net $ 3,226 $ 3,763 $ 223 $ 3,986 Additions/transfers from loans — 85 — 85 Dispositions/sales (1,572 ) (385 ) (223 ) (608 ) Valuation adjustments (90 ) 66 — 66 Ending balance, net $ 1,564 $ 3,529 — $ 3,529 Ending valuation allowance $ (152 ) $ (300 ) — $ (300 ) Ending number of foreclosed assets 10 12 — 12 Proceeds from sale of foreclosed assets $ 1,943 $ 510 $ 216 $ 726 Gain (loss) on sale of foreclosed assets $ 371 $ 125 $ (7 ) $ 118 As of March 31, 2018, $836,000 of foreclosed residential real estate properties, all of which the Company has obtained physical possession of, are included in foreclosed assets. At March 31, 2018, the recorded investment of consumer mortgage loans secured by residential real estate properties for which formal foreclosure proceedings are underway is $407,000.

Premises and Equipment

Premises and Equipment	3 Months Ended
	Mar. 31, 2018
Property, Plant and Equipment [Abstract]
Premises and Equipment	Note 7 – Premises and Equipment Premises and equipment were comprised of: March 31, December 31, (In thousands) Land & land improvements $ 9,959 $ 9,959 Buildings 50,792 50,340 Furniture and equipment 37,348 35,939 98,099 96,238 Less: Accumulated depreciation (41,678 ) (40,644 ) 56,421 55,594 Construction in progress 2,137 2,148 Total premises and equipment $ 58,558 $ 57,742 Depreciation expense for premises and equipment amounted to $1,371,000 and $1,311,000 for the three months ended March 31, 2018 and 2017, respectively.

Cash Value of Life Insurance

Cash Value of Life Insurance	3 Months Ended
	Mar. 31, 2018
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): Three months ended March 31, 2018 2017 Beginning balance $ 97,783 $ 95,912 Increase in cash value of life insurance 608 685 Gain on death benefit — 107 Insurance proceeds receivable reclassified to other assets — (921 ) Ending balance $ 98,391 $ 95,783 End of period death benefit $ 159,640 $ 164,574 Number of policies owned 182 183 Insurance companies used 14 14 Current and former employees and directors covered 57 58 As of March 31, 2018, 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	3 Months Ended
	Mar. 31, 2018
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: (in thousands) March 31, Additions Reductions December 31, Goodwill $ 64,311 — — $ 64,311 The following table summarizes the Company’s core deposit intangibles as of the dates indicated: (in thousands) March 31, Additions Reductions/ December 31, Core deposit intangibles $ 9,558 — — $ 9,558 Accumulated amortization (4,723 ) — $ (339 ) (4,384 ) Core deposit intangibles, net $ 4,835 — $ (339 ) $ 5,174 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, and $898,000 in conjunction with the Citizens acquisition on September 23, 2011. The following table summarizes the Company’s remaining estimated core deposit intangible amortization (in thousands): Years Ended Estimated Core Deposit 2018 $ 1,324 2019 1,228 2020 1,228 2021 969 2022 280 Thereafter 145

Mortgage Servicing Rights

Mortgage Servicing Rights	3 Months Ended
	Mar. 31, 2018
Text Block [Abstract]
Mortgage Servicing Rights	Note 10 – Mortgage Servicing Rights The following tables summarize the activity in, and the main assumptions used to determine the fair value of mortgage servicing rights (“MSRs”) for the periods indicated (dollars in thousands): Three months ended March 31, 2018 2017 Balance at beginning of period $ 6,687 $ 6,595 Additions 155 278 Change in fair value 111 (13 ) Balance at end of period $ 6,953 $ 6,860 Contractually specified servicing fees, late fees and ancillary fees earned $ 517 $ 521 Balance of loans serviced at: Beginning of period $ 811,065 $ 816,623 End of period $ 806,478 $ 822,506 Weighted-average prepayment speed (CPR) 7.5 % 8.3 % Weighted-average discount rate 13.0 % 14.0 % The changes in fair value of MSRs that occurred during the three months ended March 31, 2018 and 2017 were mainly 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.

Indemnification Asset

Indemnification Asset	3 Months Ended
	Mar. 31, 2018
Text Block [Abstract]
Indemnification Asset	Note 11 – Indemnification Asset A summary of the activity in the balance of indemnification asset follows (in thousands): Three months ended March 31, 2018 2017 Beginning balance — $ (744 ) Effect of actual and estimated future covered losses and recoveries — (191 ) Reimbursable (revenue) expenses incurred — (32 ) Payments made to (received from) FDIC — 72 Ending balance — $ (895 ) Amount of indemnification liability recorded in other assets — $ (179 ) Amount of indemnification liability recorded in other liabilities — (716 ) Ending balance — $ (895 ) 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	3 Months Ended
	Mar. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other Assets	Note 12 – Other Assets Other assets were comprised of (in thousands): March 31, December 31, Deferred tax asset, net $ 26,266 $ 21,697 Investment in low income housing tax credit funds 17,095 16,854 Prepaid expense 4,411 4,111 Tax refund receivable 4,754 4,754 Capital trusts 1,709 1,706 Software 883 1,126 Life insurance proceeds receivable — 2,242 Miscellaneous other assets 1,156 2,561 Total other assets $ 56,274 $ 55,051

Deposits

Deposits	3 Months Ended
	Mar. 31, 2018
Banking and Thrift [Abstract]
Deposits	Note 13 – Deposits A summary of the balances of deposits follows (in thousands): March 31, December 31, Noninterest-bearing demand $ 1,359,996 $ 1,368,218 Interest-bearing demand 1,022,299 971,459 Savings 1,395,481 1,364,518 Time certificates, over $250,000 76,306 73,596 Other time certificates 230,322 231,340 Total deposits $ 4,084,404 $ 4,009,131 Certificate of deposit balances of $50,000,000 from the State of California were included in time certificates, $250,000 and over, at each of March 31, 2018 and December 31, 2017. 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 $1,085,000 and $1,366,000 were classified as consumer loans at March 31, 2018 and December 31, 2017, respectively.

Reserve for Unfunded Commitment

Reserve for Unfunded Commitments	3 Months Ended
	Mar. 31, 2018
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 (in thousands): Three months ended March 31, 2018 2017 Balance at beginning of period $ 3,164 $ 2,719 Provision for losses – unfunded commitments 700 15 Balance at end of period $ 3,864 $ 2,734

Other Liabilities

Other Liabilities	3 Months Ended
	Mar. 31, 2018
Other Liabilities Disclosure [Abstract]
Other Liabilities	Note 15 – Other Liabilities Other liabilities were comprised of (in thousands): March 31, December 31, Pension liability $ 28,686 $ 28,472 Low income housing tax credit fund commitments 7,677 8,554 Deferred compensation 6,809 6,605 Taxes payable 5,243 — Accrued salaries and benefits expense 5,180 6,619 Joint beneficiary agreements 3,429 3,365 Loan escrow and servicing payable 1,464 1,958 Deferred revenue 1,077 1,228 Litigation contingency — 1,450 Miscellaneous other liabilities 3,964 5,007 Total other liabilities $ 63,529 $ 63,258

Other Borrowings

Other Borrowings	3 Months Ended
	Mar. 31, 2018
Text Block [Abstract]
Other Borrowings	Note 16 – Other Borrowings A summary of the balances of other borrowings follows: March 31, December 31, (in thousands) FHLB collateralized borrowing, fixed rate, as of March 31, 2018 of 1.87%, payable on April 2, 2018 $ 48,000 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 March 31, 2018 and December 31, 2017 of 0.05%, payable on April 2, 2018 and January 2, 2018, respectively 17,041 17,437 Total other borrowings $ 65,041 $ 122,166 The Company did not enter into any repurchase agreements during the three months ended March 31, 2018 or the year ended December 31, 2017. The Company maintains a collateralized line of credit with the Federal Home Loan Bank of San Francisco. Based on the FHLB stock requirements at March 31, 2018, this line provided for maximum borrowings of $1,597,695,000 of which $48,000,000 was outstanding, leaving $1,549,695,000 available. As of March 31, 2018, the Company has designated investment securities with fair value of $205,777,000 and loans totaling $2,138,150,000 as potential collateral under this collateralized line of credit with the FHLB. The Company had $17,041,000 and $17,437,000 of other collateralized borrowings at March 31, 2018 and December 31, 2017, respectively. Other collateralized borrowings are generally overnight maturity borrowings from non-financial The Company maintains a collateralized line of credit with the San Francisco Federal Reserve Bank. As of March 31, 2018, this line provided for maximum borrowings of $140,921,000 of which zero was outstanding, leaving $140,921,000 available. As of March 31, 2018, the Company has designated investment securities with fair value of $15,677 and loans totaling $262,663,000 as potential collateral under this collateralized line of credit with the San Francisco Federal Reserve Bank. The Company had available unused correspondent banking lines of credit from commercial banks totaling $20,000,000 for federal funds transactions at March 31, 2018.

Junior Subordinated Debt

Junior Subordinated Debt	3 Months Ended
	Mar. 31, 2018
Text Block [Abstract]
Junior Subordinated Debt	Note 17 – Junior Subordinated Debt At March 31, 2018, 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): Subordinated Debt Series Coupon Rate As of March 31, 2018 December 31, 2017 Maturity Face (Variable) Current Recorded Recorded Date Value 3 mo. LIBOR + Coupon Rate Book Value Book Value TriCo Cap Trust I 10/7/2033 $ 20,619 3.05 % 4.77 % $ 20,619 $ 20,619 TriCo Cap Trust II 7/23/2034 20,619 2.55 % 4.29 % 20,619 20,619 North Valley Trust II 4/24/2033 6,186 3.25 % 5.02 % 5,145 5,135 North Valley Trust III 4/24/2034 5,155 2.80 % 4.54 % 4,050 4,041 North Valley Trust IV 3/15/2036 10,310 1.33 % 3.45 % 6,472 6,444 $ 62,889 $ 56,905 $ 56,858 During the three months ended March 31, 2018, the balance of Junior Subordinated Debt increased $47,000 to $56,905,000 due to purchase fair value discount amortization.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 18 – Commitments and Contingencies Restricted Cash Balances Lease Commitments non-cancelable 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 Rent expense under operating leases was $921,000 and $1,047,000 during the three months ended March 31, 2018 and 2017, respectively. Rent expense was offset by rent income of $10,000 and $13,000 during the three months ended March 31, 2018 and 2017, respectively. 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 Company’s commitments and contingent liabilities: (in thousands) March 31, December 31, Financial instruments whose amounts represent risk: Commitments to extend credit: Commercial loans $ 253,001 $ 257,220 Consumer loans 437,790 422,958 Real estate mortgage loans 73,618 66,267 Real estate construction loans 236,650 187,097 Standby letters of credit 11,573 13,075 Deposit account overdraft privilege 101,411 98,260 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 Other Commitments and Contingencies The Company 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 March 31, 2018, the value of the Class A shares was $119.62 per share. Utilizing the conversion ratio, the value of unredeemed Class A equivalent shares owned by the Bank was $2,641,000 as of March 31, 2018, 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 Company. Management believes that any liabilities that may result from such recourse provisions are not significant.

Shareholders' Equity

Shareholders' Equity	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Shareholders' Equity	Note 19 – Shareholders’ Equity Dividends Paid The Bank paid to the Company cash dividends in the aggregate amounts of $4,372,000 and $4,042,000 during the three months ended March 31, 2018 and 2017, 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 March 31, 2018, the Company had repurchased 166,600 shares under this plan. Stock Repurchased Under Equity Compensation Plans During the three months ended March 31, 2018 and 2017, employees tendered 134 and 16,251 shares, respectively, of the Company’s common stock with market value of $4,000, and $604,000, respectively, in lieu of cash to exercise options to purchase shares of the Company’s stock and to pay income taxes related to equity compensation plan instruments 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 on August 21, 2007.

Stock Options and Other Equity-

Stock Options and Other Equity-Based Incentive Instruments	3 Months Ended
	Mar. 31, 2018
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 Restricted Stock Unit Award. 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 March 31, 2018, 446,400 options for the purchase of common shares, and 121,102 restricted stock units were outstanding, and 526,418 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 March 31, 2018, 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 during the three months ended March 31, 2018 is summarized in the following table: Number Option Price per Share Weighted Value on Weighted Outstanding at December 31, 2017 446,400 $ 12.63 to $23.21 $ 16.84 Options granted — — to — — Options exercised — — to — — Options forfeited — — to — — Outstanding at March 31, 2018 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 March 31, 2018: Currently Currently Not Total Exercisable Exercisable Outstanding Number of options 423,600 22,800 446,400 Weighted average exercise price $ 16.65 $ 20.45 $ 16.84 Intrinsic value (in thousands) $ 8,713 $ 382 $ 9,096 Weighted average remaining contractual term (yrs.) 3.6 5.5 3.7 The 22,800 options that are currently not exercisable as of March 31, 2018 are expected to vest, on a weighted-average basis, over the next 6 months, and the Company is expected to recognize $61,000 of pre-tax 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, 2017 68,457 52,829 RSUs granted — — RSUs added through dividend credits 310 — RSUs released (494 ) — RSUs forfeited/expired — — Outstanding at March 31, 2018 68,273 52,829 The 68,273 of service condition vesting RSUs outstanding as of March 31, 2018 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 68,273 of service condition vesting RSUs outstanding as of March 31, 2018 are expected to vest, and be released, on a weighted-average basis, over the next 1.0 year. The Company expects to recognize $1,211,000 of pre-tax The 52,829 of market plus service condition vesting RSUs outstanding as of March 31, 2018 are expected to vest, and be released, on a weighted-average basis, over the next 1.2 years. The Company expects to recognize $608,000 of pre-tax

Noninterest Income and Expense

Noninterest Income and Expense	3 Months Ended
	Mar. 31, 2018
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): Three months ended March 31, 2018 2017 Service charges on deposit accounts $ 3,779 $ 3,619 ATM and interchange fees 4,235 4,015 Other service fees 714 765 Mortgage banking service fees 517 521 Change in value of mortgage servicing rights 111 (13 ) Total service charges and fees 9,356 8,907 Commissions on sale of non-deposit 876 607 Gain on sale of loans 626 910 Increase in cash value of life insurance 608 685 Gain on sale of foreclosed assets 371 118 Lease brokerage income 128 206 Sale of customer checks 101 104 Change in indemnification asset — (221 ) Life insurance proceeds in excess of cash value — 107 Loss on disposal of fixed assets (13 ) — Loss on marketable equity securities (47 ) — Other 284 280 Total other noninterest income 2,934 2,796 Total noninterest income $ 12,290 $ 11,703 Mortgage loan servicing fees, net of change in fair value of mortgage loan servicing rights, totaling $628,000 and $508,000 were recorded in service charges and fees noninterest income for the three months ended March 31, 2018 and 2017, respectively. The components of noninterest expense were as follows (in thousands): Three months ended March 31, 2018 2017 Base salaries, net of deferred loan origination costs $ 13,962 $ 13,390 Incentive compensation 2,452 2,198 Benefits and other compensation costs 5,238 5,305 Total salaries and benefits expense 21,652 20,893 Occupancy 2,681 2,692 Data processing and software 2,514 2,396 Equipment 1,551 1,723 ATM and POS network charges 1,226 853 Advertising 838 967 Professional fees 773 766 Telecommunications 701 643 Change in reserve for unfunded commitments 700 15 Merger and acquisition expense 476 — Assessments 430 405 Postage 358 404 Intangible amortization 339 359 Operational losses 294 435 Courier service 267 254 Provision for (reversal of) foreclosed asset losses 90 (66 ) Foreclosed assets expense 24 38 Other miscellaneous expense 3,248 3,045 Total other noninterest expense 16,510 14,929 Total noninterest expense $ 38,162 $ 35,822 Merger and acquisition expense: Professional fees $ 355 — Advertising and marketing 8 — Other miscellaneous expense 112 — Total merger and acquisition expense $ 476 —

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Note 22 – Income Taxes The provisions for income taxes applicable to income before taxes 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 for the periods indicated as follows: Three months ended March 31, 2018 2017 Federal statutory income tax rate 21.0 % 35.0 % State income taxes, net of federal tax benefit 9.0 6.9 Tax-exempt (1.1 ) (1.9 ) Increase in cash value of insurance policies (0.7 ) (1.4 ) Low income housing tax credits (1.0 ) (0.6 ) Equity compensation — (0.5 ) Nondeductible merger expenses 0.4 — Nondeductible joint beneficiary agreement expense 0.1 0.1 Other 0.4 0.2 Effective Tax Rate 28.1 % 37.8 %

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Earnings Per Share	Note 23 – Earnings Per Share Basic earnings per share represent income available to common shareholders divided by the weighted-average number of common shares outstanding during the period. Diluted earnings per share reflect 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: Three months ended March 31, (in thousands) 2018 2017 Net income $ 13,910 $ 12,079 Average number of common shares outstanding 22,956 22,870 Effect of dilutive stock options and restricted stock 327 362 Average number of common shares outstanding used to calculate diluted earnings per share 23,283 23,232 Options excluded from diluted earnings per share because the effect of these options was antidilutive — —

Comprehensive Income

Comprehensive Income	3 Months Ended
	Mar. 31, 2018
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 Three months ended March 31, (in thousands) 2018 2017 Unrealized holding gains (losses) on available for sale securities before reclassifications $ (15,265 ) $ 787 Amounts reclassified out of accumulated other comprehensive income: Adoption ASU 2016-01 62 — Adoption ASU 2018-02 (425 ) — Total amounts reclassified out of accumulated other comprehensive income (363 ) — Unrealized holding gains (losses) on available for sale securities after reclassifications (15,628 ) 787 Tax effect 4,602 (330 ) Unrealized holding gains (losses) on available for sale securities, net of tax (11,026 ) 457 Change in unfunded status of the supplemental retirement plans before reclassifications 667 — Amounts reclassified out of accumulated other comprehensive income: Amortization of prior service cost (13 ) (3 ) Amortization of actuarial losses 127 96 Adoption ASU 2018-02 (668 ) — Total amounts reclassified out of accumulated other comprehensive income (554 ) 93 Change in unfunded status of the supplemental retirement plans after reclassifications 113 93 Tax effect (33 ) (39 ) Change in unfunded status of the supplemental retirement plans, net of tax 80 54 Change in joint beneficiary agreement liability before reclassifications — — Amounts reclassified out of accumulated other comprehensive income — — Change in joint beneficiary agreement liability after reclassifications — — Tax effect — — Change in joint beneficiary agreement liability, net of tax — — Total other comprehensive income (loss) $ (10,946 ) $ 511 The components of accumulated other comprehensive income, included in shareholders’ equity, are as follows: Three months ended March 31, (in thousands) 2018 2017 Net unrealized loss on available for sale securities $ (18,975 ) $ (8,083 ) Tax effect 5,610 3,399 Unrealized holding loss on available for sale securities, net of tax (13,365 ) (4,684 ) Unfunded status of the supplemental retirement plans (5,238 ) (4,621 ) Tax effect 1,549 1,943 Unfunded status of the supplemental retirement plans, net of tax (3,689 ) (2,678 ) Joint beneficiary agreement liability (151 ) (40 ) Tax effect — — Joint beneficiary agreement liability, net of tax (151 ) (40 ) Accumulated other comprehensive loss $ (17,205 ) $ (7,402 )

Retirement Plans

Retirement Plans	3 Months Ended
	Mar. 31, 2018
Retirement Benefits [Abstract]
Retirement Plans	Note 25 - Retirement Plans 401(k) Plan The Company sponsors a 401(k) Plan that allows participants to 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 $203,000, and $186,000 of salaries & benefits expense attributable to the 401(k) Plan matching contributions during the three months ended March 31, 2018 and 2017, respectively. The Company made contributions to the 401(k) Plan of $199,000 and $179,000 during the three months ended March 31, 2018 and 2017, 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 $465,000 and $525,000 during the three months ended March 31, 2018 and 2017, respectively, are included in salary expense. 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 $6,809,000 and $6,605,000 at March 31, 2018 and December 31, 2017, respectively. Earnings credits on deferred balances totaling $124,000 and $145,000 during the three months ended March 31, 2018 and 2017, respectively, are included in noninterest expense. Supplemental Retirement Plans The Company has supplemental retirement plans for current and former directors and key executives. These plans are non-qualified Three months ended March 31, 2018 2017 (in thousands) Net pension cost included the following components: Service cost-benefits earned during the period $ 243 $ 235 Interest cost on projected benefit obligation 237 249 Amortization of net obligation at transition 1 1 Amortization of prior service cost (13 ) (3 ) Recognized net actuarial loss 127 96 Net periodic pension cost $ 595 $ 578 During the three months ended March 31, 2018 and 2017, the Company contributed and paid out as benefits $267,000 and $259,000, respectively, to participants under the plans. For the year ending December 31, 2018, the Company expects to contribute and pay out as benefits $1,106,000 to participants under the plans.

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2018
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 periods indicated (in thousands): Balance December 31, 2016 $ 2,432 Advances/new loans 437 Removed/payments (721 ) Balance December 31, 2017 2,148 Advances/new loans 145 Removed/payments (314 ) Balance March 31, 2018 $ 1,979 Deposits of directors, officers and other related parties to the Bank totaled $30,871,000 and $46,025,000 at March 31, 2018 and December 31, 2017, respectively.

Fair Value Measurement

Fair Value Measurement	3 Months Ended
	Mar. 31, 2018
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): Fair value at March 31, 2018 Total Level 1 Level 2 Level 3 Marketable equity securities $ 2,890 $ 2,890 $ — $ — Debt securities available for sale: Obligations of U.S. government corporations and agencies 616,657 — 616,657 — Obligations of states and political subdivisions 119,238 — 119,238 — Mortgage servicing rights 6,953 — — 6,953 Total assets measured at fair value $ 745,738 $ 2,890 $ 735,895 $ 6,953 Fair value at December 31, 2017 Total Level 1 Level 2 Level 3 Marketable equity securities $ 2,938 $ 2,938 $ — $ — Debt 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 — Mortgage servicing rights 6,687 — — 6,687 Total assets measured at fair value $ 737,570 $ 2,938 $ 727,945 $ 6,687 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 the three months ended March 31, 2018 or the year ended December 31, 2017. 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 time periods indicated. Had there been any transfer into or out of Level 3 during the time periods indicated, 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): Three months ended March 31, Beginning Transfers Change Issuances Ending 2018: Mortgage servicing rights $ 6,687 — $ 111 $ 155 $ 6,953 2017: Mortgage servicing rights $ 6,595 — $ (13 ) $ 278 $ 6,860 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 March 31, 2018: Fair Value Valuation Unobservable Range, Mortgage Servicing Rights $ 6,953 Discounted cash flow Constant prepayment rate 6.0%-19.7%, 7.5 % Discount rate 11.0%-15.0%, 13.0% The following table presents quantitative information about recurring Level 3 fair value measurements at December 31, 2017: Fair Value Valuation Unobservable Range, 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% The tables below present the recorded investment in assets and liabilities measured at fair value on a nonrecurring basis, as of the dates indicated (in thousands): Three months ended March 31, 2018 Total Level 1 Level 2 Level 3 Total Gains Fair value: Impaired Originated & PNCI loans $ 2,103 — — $ 2,103 $ (795 ) Foreclosed assets 774 — — 774 (87 ) Total assets measured at fair value $ 2,877 — — $ 2,877 $ (882 ) Year ended December 31, 2017 Total Level 1 Level 2 Level 3 Total Gains 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 ) Three months ended March 31, 2017 Total Level 1 Level 2 Level 3 Total Gains Fair value: Impaired Originated & PNCI loans $ 824 — — $ 824 $ 30 Foreclosed assets 1,528 — — 1,528 (22 ) Total assets measured at fair value $ 2,352 — — $ 2,352 $ 8 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 Company 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 March 31, 2018: March 31, 2018 Fair Value Valuation Technique Unobservable Inputs Range, Impaired Originated & PNCI loans $ 2,103 Sales comparison Income approach Adjustment for differences Not meaningful Foreclosed assets (Land & construction) $ 190 Sales comparison Adjustment for differences Not meaningful Foreclosed assets (Residential real estate) $ 492 Sales comparison Adjustment for differences Not meaningful Foreclosed assets (Commercial real estate) $ 92 Sales comparison Adjustment for differences Not meaningful 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: December 31, 2017 Fair Value Valuation Unobservable Inputs Range, Impaired Originated & PNCI loans $ 2,767 Sales comparison Adjustment for differences Not meaningful Foreclosed assets (Land & construction) $ 1,341 Sales comparison Adjustment for differences Not meaningful Foreclosed assets (Residential real estate) $ 622 Sales comparison Adjustment for differences Not meaningful Foreclosed assets (Commercial real estate) $ 254 Sales comparison Adjustment for differences Not meaningful 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. In January 2018, the Company adopted the provisions of Accounting Standard Update 2016-01 Recognition and Measurement of Financial Assets and Financial Liabilities March 31, 2018 December 31, 2017 Carrying Fair Carrying Fair Financial assets: Level 1 inputs: Cash and due from banks $ 87,138 $ 87,138 $ 105,968 $ 105,968 Cash at Federal Reserve and other banks 95,841 95,841 99,460 99,460 Level 2 inputs: Securities held to maturity 496,035 488,639 514,844 518,165 Restricted equity securities 16,956 N/A 16,956 N/A Loans held for sale 2,149 2,149 4,616 4,616 Level 3 inputs: Loans, net 3,039,760 3,025,636 2,984,842 2,992,225 Financial liabilities: Level 2 inputs: Deposits 4,084,404 4,081,089 4,009,131 4,006,620 Other borrowings 65,041 65,041 122,166 122,166 Level 3 inputs: Junior subordinated debt 56,905 59,982 56,858 58,466 Contract Fair Contract Fair Off-balance Level 3 inputs: Commitments $ 1,001,059 $ 10,011 $ 933,542 $ 9,335 Standby letters of credit 11,573 116 13,075 131 Overdraft privilege commitments 101,411 1,014 98,260 983

TriCo Bancshares Condensed Fina

TriCo Bancshares Condensed Financial Statements (Parent Only)	3 Months Ended
	Mar. 31, 2018
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 March 31, December 31, (In thousands) Assets Cash and cash equivalents $ 3,516 $ 3,924 Investment in Tri Counties Bank 557,380 557,538 Other assets 1,758 1,721 Total assets $ 562,654 $ 563,183 Liabilities and shareholders’ equity Other liabilities $ 493 $ 517 Junior subordinated debt 56,905 56,858 Total liabilities 57,398 57,375 Shareholders’ equity: Preferred stock, no par value: 1,000,000 shares authorized, zero issued and outstanding at March 31, 2018 and December 31, 2017 — — Common stock, no par value: authorized 50,000,000 shares; issued and outstanding 22,956,323 and 22,955,963 shares, respectively 256,226 255,836 Retained earnings 266,235 255,200 Accumulated other comprehensive loss, net (17,205 ) (5,228 ) Total shareholders’ equity 505,256 505,808 Total liabilities and shareholders’ equity $ 562,654 $ 563,183 Condensed Statements of Income Three months ended March 31, 2018 2017 (In thousands) Interest expense $ (697 ) $ (595 ) Administration expense (426 ) (159 ) Loss before equity in net income of Tri Counties Bank (1,123 ) (754 ) Equity in net income of Tri Counties Bank: Distributed 4,372 4,042 Undistributed 10,397 8,474 Income tax benefit 264 317 Net income $ 13,910 $ 12,079 Condensed Statements of Comprehensive Income Three months ended March 31, 2018 2017 (In thousands) Net income $ 13,910 $ 12,079 Other comprehensive income (loss), net of tax: Increase (decrease) in unrealized gains on available for sale securities arising during the period (11,026 ) 457 Change in minimum pension liability 80 54 Other comprehensive income (loss) (10,946 ) 511 Comprehensive income $ 2,964 $ 12,590 Condensed Statements of Cash Flows Three months ended March 31, 2018 2017 (In thousands) Operating activities: Net income $ 13,910 $ 12,079 Adjustments to reconcile net income to net cash provided by operating activities: Undistributed equity in earnings of Tri Counties Bank (10,397 ) (8,474 ) Equity compensation vesting expense 391 381 Stock option excess tax benefits — Net change in other assets and liabilities (405 ) (348 ) Net cash provided by operating activities 3,499 3,638 Investing activities: None Financing activities: Repurchase of common stock (4 ) (169 ) Cash dividends paid — common (3,903 ) (3,431 ) Net cash used for financing activities (3,907 ) (3,600 ) Net change in cash and cash equivalents (408 ) 38 Cash and cash equivalents at beginning of year 3,924 2,802 Cash and cash equivalents at end of year $ 3,516 $ 2,840

Regulatory Matters

Regulatory Matters	3 Months Ended
	Mar. 31, 2018
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 Quantitative measures established by regulation to ensure capital adequacy require the Company to maintain minimum amounts and ratios (set forth in the table below) of total, Tier 1, and common equity Tier 1capital to risk-weighted assets, and of Tier 1 capital to average assets. The following tables present actual and required capital ratios as of March 31, 2018 and December 31, 2017 for the Company and the Bank under Basel III Capital Rules. The minimum capital amounts presented include the minimum required capital levels as of March 31, 2018 (1.875%) and December 31, 2017 (1.25%) based on the then phased-in phased-in. Minimum Capital Minimum Capital Required to be Required – Basel III Required – Basel III Considered Well Actual Phase-in Fully Phased In Capitalized Amount Ratio Amount Ratio Amount Ratio Amount Ratio (dollars in thousands) As of March 31, 2018: Total Capital (to Risk Weighted Assets): Consolidated $539,966 13.91 % $ 383,434 9.875 % $ 407,702 10.50 % N/A N/A Tri Counties Bank $536,894 13.83 % $ 383,261 9.875 % $ 407,518 10.50 % $ 388,112 10.00 % Tier 1 Capital (to Risk Weighted Assets): Consolidated $506,129 13.03 % $ 305,777 7.875 % $ 330,045 8.50 % N/A N/A Tri Counties Bank $503,057 12.96 % $ 305,638 7.875 % $ 329,895 8.50 % $ 310,490 8.00 % Common equity Tier 1 Capital (to Risk Weighted Assets): Consolidated $450,933 11.61 % $ 247,534 6.375 % $ 271,802 7.00 % N/A N/A Tri Counties Bank $503,057 12.96 % $ 247,421 6.375 % $ 271,678 7.00 % $ 252,273 6.50 % Tier 1 Capital (to Average Assets): Consolidated $506,129 10.84 % $ 186,720 4.000 % $ 186,720 4.00 % N/A N/A Tri Counties Bank $503,057 10.78 % $ 186,716 4.000 % $ 186,716 4.00 % $ 233,395 5.00 % 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 9.25 % $ 394,679 10.50 % N/A N/A Tri Counties Bank $ 525,384 13.98 % $ 347,535 9.25 % $ 394,499 10.50 % $ 375,713 10.00 % Tier 1 Capital (to Risk Weighted Assets): Consolidated $ 495,318 13.18 % $ 272,517 7.25 % $ 319,502 8.50 % N/A N/A Tri Counties Bank $ 491,897 13.09 % $ 272,392 7.25 % $ 319,356 8.50 % $ 300,570 8.00 % Common equity Tier 1 Capital (to Risk Weighted Assets): Consolidated $ 440,643 11.72 % $ 216,134 5.75 % $ 263,120 7.00 % N/A N/A Tri Counties Bank $ 491,897 13.09 % $ 216,035 5.75 % $ 262,999 7.00 % $ 244,214 6.50 % Tier 1 Capital (to Average Assets): Consolidated $ 495,318 10.80 % $ 183,400 4.00 % $ 183,400 4.00 % N/A N/A Tri Counties Bank $ 491,897 10.73 % $ 183,394 4.00 % $ 183,394 4.00 % $ 229,243 5.00 % As of March 31, 2018, 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 March 31, 2018, the Company and the Bank are in compliance with the capital conservation buffer requirement. 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)	3 Months Ended
	Mar. 31, 2018
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 periods indicated, 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. 2018 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 $ 246 Discount accretion PCI – other 60 Discount accretion PNCI 326 All other loan interest income 37,417 Total loan interest income 38,049 Debt securities, dividends and interest bearing cash at banks (not FTE) 9,072 Total interest income 47,121 Interest expense 2,135 Net interest income 44,986 (Benefit from reversal of) provision for loan losses (236 ) Net interest income after provision for loan losses 45,222 Noninterest income 12,290 Noninterest expense 38,162 Income before income taxes 19,350 Income tax expense 5,440 Net income $ 13,910 Per common share: Net income (diluted) $ 0.60 Dividends $ 0.17 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

Summary of Significant Accoun39

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2018
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 and 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 consolidated 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 $1,703,000 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. The Company currently classifies all its operation into one business segment that it denotes as community banking.
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.
Marketable Equity Securities	Marketable Equity Securities As of December 31, 2017, marketable equity securities with a fair value of $2,938,000 were recorded within investment securities available for sale on the consolidated balance sheets with changes in the fair value recorded through other comprehensive income and accumulated other comprehensive income (loss). As of January 1, 2018, the Company adopted Accounting Standard Update (“ASU”) 2016-01
Debt Securities	Debt Securities The Company classifies its debt 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. During the three months ended March 31, 2018 and throughout 2017, the Company did not have any debt 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. On May 9, 2017, the Company and the FDIC terminated their loss sharing agreements.
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 purchase 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 credits and other loans, standby letters of credits, and unused deposit account overdraft privilege. 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.
Revenue Recognition	Revenue Recognition The Company records revenue from contracts with customers in accordance with Accounting Standards Codification Topic 606, “Revenue from Contracts with Customers” (“Topic 606”). Under Topic 606, the Company must identify the contract with a customer, identify the performance obligations in the contract, determine the transaction price, allocate the transaction price to the performance obligations in the contract, and recognize revenue when (or as) the Company satisfies a performance obligation. Significant revenue has not been recognized in the current reporting period that results from performance obligations satisfied in previous periods. Most of our revenue-generating transactions are not subject to ASC 606, including revenue generated from financial instruments, such as our loans and investment securities. In addition, certain noninterest income streams such as fees associated with mortgage servicing rights, financial guarantees, derivatives, and certain credit card fees are also not in scope of the new guidance. The Company’s noninterest revenue streams are largely based on transactional activity, or standard month-end month-end
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 1st lien and 2nd lien non-owner occupied 1-4 residential real estate mortgage loans from commercial real estate mortgage loans to residential real estate mortgage loans and consumer home equity loans, respectively. This change in loan category classification was made to better align the Company’s financial reporting classifications with regulatory reporting classifications, and to properly classify these loans for regulatory risk-based capital ratio calculations. Certain amounts reported in previous consolidated financial statements have been reclassified and recalculated to conform to the presentation in this report. These reclassifications did not affect previously reported net income, total loans or total shareholders’ equity.
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 In January 2016, the FASB issued ASU No. 2016-01, “Recognition and Measurement of Financial Assets and Financial Liabilities.” available-for-sale No. 2016-01 Fair Value Measurement FASB issued Accounting Standard Update (ASU) No. 2016-02 , Leases (Topic 842) ASU 2016-2, on-balance ASU 2016-02 No. 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, 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

Investment Securities (Tables)

Investment Securities (Tables)	3 Months Ended
	Mar. 31, 2018
Investments Schedule [Abstract]
Amortized Cost and Estimated Fair Values of Investments in Debt Securities	The amortized cost and estimated fair values of investments in debt securities are summarized in the following tables: March 31, 2018 Amortized Gross Gross Estimated (in thousands) Debt Securities Available for Sale Obligations of U.S. government corporations and agencies $ 633,310 $ 317 $ (16,970 ) $ 616,657 Obligations of states and political subdivisions 121,560 466 (2,788 ) 119,238 Total debt securities available for sale $ 754,870 $ 783 $ (19,758 ) $ 735,895 Debt Securities Held to Maturity Obligations of U.S. government corporations and agencies $ 481,457 $ 533 $ (7,737 ) $ 474,253 Obligations of states and political subdivisions 14,578 39 (231 ) 14,386 Total debt securities held to maturity $ 496,035 $ 572 $ (7,968 ) $ 488,639 December 31, 2017 Amortized Gross Gross Estimated (in thousands) Debt 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 Total debt securities available for sale $ 731,292 $ 2,583 $ (5,930 ) $ 727,945 Debt 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 debt securities held to maturity $ 514,844 $ 5,247 $ (1,926 ) $ 518,165
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. Debt Securities Available for Sale Held to Maturity (In thousands) Amortized Estimated Amortized Estimated Due in one year $ 2 $ 2 $ — $ — Due after one year through five years 235 236 1,215 1,228 Due after five years through ten years 3,324 3,452 20,631 20,291 Due after ten years 751,309 732,205 474,189 467,120 Totals $ 754,870 $ 735,895 $ 496,035 $ 488,639
Gross Unrealized Losses on Debt Securities	Gross unrealized losses on debt 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 Fair Unrealized Fair Unrealized Fair Unrealized (in thousands) March 31, 2018 Debt Securities Available for Sale Obligations of U.S. government corporations and agencies $ 434,302 $ (10,345 ) $ 158,324 $ (6,625 ) $ 592,626 $ (16,970 ) Obligations of states and political subdivisions 65,047 (1,456 ) 16,042 (1,332 ) 81,089 (2,788 ) Total debt securities available for sale $ 499,349 $ (11,801 ) $ 174,366 $ (7,957 ) $ 673,715 $ (19,758 ) Debt Securities Held to Maturity Obligations of U.S. government corporations and agencies $ 299,575 $ (4,551 ) $ 89,809 $ (3,186 ) $ 389,384 $ (7,737 ) Obligations of states and political subdivisions 8,901 (144 ) 2,579 (87 ) 11,480 (231 ) Total debt securities held to maturity $ 308,476 $ (4,695 ) $ 92,388 $ (3,273 ) $ 400,864 $ (7,968 ) Less than 12 months 12 months or more Total Fair Unrealized Fair Unrealized Fair Unrealized (in thousands) December 31, 2017 Debt 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 ) Total securities available for sale $ 289,271 $ (2,211 ) $ 183,423 $ (3,719 ) $ 472,694 $ (5,930 ) Debt 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 debt securities held to maturity $ 94,505 $ (574 ) $ 98,004 $ (1,352 ) $ 192,509 $ (1,926 )

Loans (Tables)

Loans (Tables)	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Summary of Loan Balances	A summary of loan balances follows (in thousands): March 31, 2018 Originated PNCI PCI - PCI - Total Mortgage loans on real estate: Residential 1-4 $ 323,161 $ 61,206 $ — $ 1,744 $ 386,111 Commercial 1,754,062 211,168 — 8,038 1,973,268 Total mortgage loan on real estate 2,077,223 272,374 — 9,782 2,359,379 Consumer: Home equity lines of credit 266,651 14,939 1,619 42 283,251 Home equity loans 38,889 2,558 — 485 41,932 Other 21,422 2,141 — 43 23,606 Total consumer loans 326,962 19,638 1,619 570 348,789 Commercial 205,673 7,837 — 2,505 216,015 Construction: Residential 71,589 9 — — 71,598 Commercial 73,701 251 — — 73,952 Total construction 145,290 260 — — 145,550 Total loans, net of deferred loan fees and discounts $ 2,755,148 $ 300,109 $ 1,619 $ 12,857 $ 3,069,733 Total principal balance of loans owed, net of charge-offs $ 2,764,819 $ 306,924 $ 5,167 $ 16,654 $ 3,093,564 Unamortized net deferred loan fees (9,671 ) — — — (9,671 ) Discounts to principal balance of loans owed, net of charge-offs — (6,815 ) (3,548 ) (3,797 ) (14,160 ) Total loans, net of unamortized deferred loan fees and discounts $ 2,755,148 $ 300,109 $ 1,619 $ 12,857 $ 3,069,733 Allowance for loan losses $ (29,057 ) $ (748 ) $ (8 ) $ (160 ) $ (29,973 ) 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 Allowance for loan losses $ (29,122 ) $ (929 ) $ (17 ) $ (255 ) $ (30,323 )
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): Three months ended March 31, 2018 2017 Change in accretable yield: Balance at beginning of period $ 4,262 $ 10,348 Accretion to interest income (255 ) (902 ) Reclassification (to) from nonaccretable difference 140 114 Balance at end of period $ 4,147 $ 9,560

Allowance for Loan Losses (Tabl

Allowance for Loan Losses (Tables)	3 Months Ended
	Mar. 31, 2018
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 – Three Months Ended March 31, 2018 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total Beginning balance $ 2,317 $ 11,441 $ 5,800 $ 1,841 $ 586 $ 6,512 $ 1,184 $ 642 $ 30,323 Charge-offs (1 ) — (80 ) — (194 ) (205 ) — — (480 ) Recoveries — 15 209 14 78 50 — — 366 (Benefit) provision (146 ) 39 (517 ) (119 ) 100 35 167 205 (236 ) Ending balance $ 2,170 $ 11,495 $ 5,412 $ 1,736 $ 570 $ 6,392 $ 1,351 $ 847 $ 29,973 Ending balance: Individ. evaluated for impairment $ 190 $ 154 $ 448 $ 130 $ 56 $ 2,113 — — $ 3,091 Loans pooled for evaluation $ 1,910 $ 11,281 $ 4,956 $ 1,606 $ 514 $ 4,249 $ 1,351 $ 847 $ 26,714 Loans acquired with deteriorated credit quality $ 70 $ 60 $ 8 — — $ 30 — — $ 168 Loans, net of unearned fees – As of March 31, 2018 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total Ending balance: Total loans $ 386,111 $ 1,973,268 $ 283,251 $ 41,932 $ 23,606 $ 216,015 $ 71,598 $ 73,952 $ 3,069,733 Individ. evaluated for impairment $ 5,535 $ 11,110 $ 2,450 $ 1,673 $ 278 $ 4,621 $ 136 — $ 25,803 Loans pooled for evaluation $ 378,832 $ 1,954,120 $ 279,140 $ 39,774 $ 23,285 $ 208,889 $ 71,462 $ 73,952 $ 3,029,454 Loans acquired with deteriorated credit quality $ 1,744 $ 8,038 $ 1,661 $ 485 $ 43 $ 2,505 — — $ 14,476 Allowance for Loan Losses—Year Ended December 31, 2017 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans 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 Other Construction (in thousands) Resid. Comm. Lines Loans 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 – Three Months Ended March 31, 2017 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans 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 — — (71 ) (31 ) (174 ) (133 ) — — (409 ) Recoveries — 110 46 12 141 170 — 1 480 (Benefit) provision (86 ) (85 ) (489 ) (174 ) 6 (542 ) (78 ) (109 ) (1,557 ) Ending balance $ 2,662 $ 11,542 $ 6,530 $ 2,451 $ 595 $ 5,326 $ 1,339 $ 572 $ 31,017 Ending balance: Individ. evaluated for impairment $ 249 $ 124 $ 400 $ 57 $ 31 $ 811 $ 14 — $ 1,686 Loans pooled for evaluation $ 2,188 $ 9,971 $ 6,122 $ 2,328 $ 564 $ 3,873 $ 1,282 $ 572 $ 26,900 Loans acquired with deteriorated credit quality $ 225 $ 1,447 $ 8 $ 66 — $ 642 $ 43 — $ 2,431 Loans, net of unearned fees – As of March 31, 2017 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total Ending balance: Total loans $ 309,701 $ 1,761,114 $ 283,596 $ 40,241 $ 29,313 $ 212,685 $ 59,699 $ 64,843 $ 2,761,192 Individ. evaluated for impairment $ 3,849 $ 16,979 $ 2,204 $ 1,241 $ 280 $ 3,072 $ 25 — $ 27,650 Loans pooled for evaluation $ 304,493 $ 1,731,785 $ 277,388 $ 37,867 $ 28,967 $ 205,832 $ 58,830 $ 64,843 $ 2,710,005 Loans acquired with deteriorated credit quality $ 1,359 $ 12,350 $ 4,004 $ 1,133 $ 66 $ 3,781 $ 844 — $ 23,537
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 March 31, 2018 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total Originated loans: Pass $ 317,799 $ 1,716,599 $ 263,270 $ 35,730 $ 21,067 $ 193,829 $ 71,482 $ 68,846 $ 2,688,622 Special mention 2,274 23,679 1,628 1,532 238 7,263 — 4,855 41,469 Substandard 3,088 13,784 1,753 1,627 117 4,581 107 — 25,057 Loss — — — — — — — — — Total originated $ 323,161 $ 1,754,062 $ 266,651 $ 38,889 $ 21,422 $ 205,673 $ 71,589 $ 73,701 $ 2,755,148 PNCI loans: Pass $ 59,184 $ 201,641 $ 13,686 $ 2,301 $ 2,067 $ 7,837 $ 9 $ 251 $ 286,976 Special mention 214 8,977 282 184 37 — — — 9,694 Substandard 1,808 550 971 73 37 — — — 3,439 Loss — — — — — — — — — Total PNCI $ 61,206 $ 211,168 $ 14,939 $ 2,558 $ 2,141 $ 7,837 $ 9 $ 251 $ 300,109 PCI loans $ 1,744 $ 8,038 $ 1,661 $ 485 $ 43 $ 2,505 — — $ 14,476 Total loans $ 386,111 $ 1,973,268 $ 283,251 $ 41,932 $ 23,606 $ 216,015 $ 71,598 $ 73,952 $ 3,069,733 Credit Quality Indicators – As of December 31, 2017 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans 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
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 March 31, 2018 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total Originated loan balance: Past due: 30-59 $ 2,217 $ 5,531 $ 938 $ 1,490 $ 63 $ 915 $ 298 $ — $ 11,452 60-89 — — 26 18 18 534 — 1,249 1,845 > 90 Days 846 1,162 320 154 — 1,557 — — 4,039 Total past due 3,063 6,693 1,284 1,662 81 3,006 298 1,249 17,336 Current 320,098 1,747,369 265,367 37,227 21,341 202,667 71,291 72,452 2,737,812 Total originated loans $ 323,161 $ 1,754,062 $ 266,651 $ 38,889 $ 21,422 $ 205,673 $ 71,589 $ 73,701 $ 2,755,148 > 90 Days and still accruing — — — — — — — — — Nonaccrual loans $ 2,235 $ 7,925 $ 733 $ 1,193 $ 4 $ 3,990 — — $ 16,080 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 March 31, 2018 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total PNCI loan balance: Past due: 30-59 $ 2,537 — $ 362 $ 2 — $ 1 — — $ 2,902 60-89 — — — — 4 — — — 4 > 90 Days — — 146 — 28 — — — 174 Total past due 2,537 — 508 2 32 1 — — 3,080 Current 58,669 211,168 14,431 2,556 2,109 7,836 9 251 297,029 Total PNCI loans $ 61,206 $ 211,168 $ 14,939 $ 2,558 $ 2,141 $ 7,837 $ 9 $ 251 $ 300,109 > 90 Days and still accruing — — — — — — — — — Nonaccrual loans $ 1,067 — $ 571 $ 40 $ 33 — — — $ 1,711 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 Other Construction (in thousands) Resid. Comm. Lines Loans 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 originated 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 Other Construction (in thousands) Resid. Comm. Lines Loans 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
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 original 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, or for the Three Months Ended, March 31, 2018 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total With no related allowance recorded: Recorded investment $ 2,678 $ 9,848 $ 888 $ 1,193 — $ 881 $ 136 — $ 15,624 Unpaid principal $ 2,829 $ 10,126 $ 944 $ 1,548 — $ 894 $ 136 — $ 16,477 Average recorded investment $ 2,368 $ 11,474 $ 991 $ 1,150 $ 2 $ 728 $ 138 — $ 16,851 Interest income recognized $ 19 $ 35 $ 6 — — $ 9 $ 2 — $ 71 With an allowance recorded: Recorded investment $ 1,525 $ 1,262 $ 527 $ 196 $ 4 $ 3,740 — — $ 7,254 Unpaid principal $ 1,549 $ 1,281 $ 534 $ 196 $ 4 $ 3,862 — — $ 7,426 Related allowance $ 190 $ 154 $ 146 $ 10 $ 4 $ 2,113 — — $ 2,617 Average recorded investment $ 1,703 $ 1,036 $ 464 $ 197 $ 4 $ 3,817 — — $ 7,221 Interest income recognized $ 9 $ 9 $ 4 $ 2 — $ 17 — — $ 41 Impaired PNCI Loans – As of, or for the Three Months Ended, March 31, 2018 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total With no related allowance recorded: Recorded investment $ 1,332 — $ 501 $ 40 $ 28 — — — $ 1,901 Unpaid principal $ 1,390 — $ 529 $ 54 $ 28 — — — $ 2,001 Average recorded investment $ 1,345 — $ 546 $ 42 $ 14 — — — $ 1,947 Interest income recognized $ 2 — $ 2 — — — — $ 4 With an allowance recorded: Recorded investment — — $ 534 $ 244 $ 246 — — — $ 1,024 Unpaid principal — — $ 536 $ 244 $ 246 — — — $ 1,026 Related allowance — — $ 302 $ 120 $ 52 — — — $ 474 Average recorded investment — — $ 568 $ 183 $ 248 — — — $ 999 Interest income recognized — — $ 3 $ 3 $ 2 — — — $ 8 Impaired Originated Loans – As of, or for the Twelve Months Ended, December 31, 2017 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans 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, or for the Twelve Months Ended, December 31, 2017 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans 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, or for the Three Months Ended, March 31, 2017 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total With no related allowance recorded: Recorded investment $ 1,782 $ 14,431 $ 1,064 $ 743 $ 5 $ 1,289 $ 11 — $ 19,325 Unpaid principal $ 1,793 $ 14,881 $ 1,144 $ 1,085 $ 6 $ 1,312 $ 16 — $ 20,237 Average recorded investment $ 2,834 $ 20,770 $ 2,013 $ 845 $ 12 $ 932 $ 7 — $ 27,413 Interest income recognized $ 20 $ 98 $ 6 $ 1 — $ 7 — — $ 132 With an allowance recorded: Recorded investment $ 1,378 $ 640 $ 427 $ 440 $ 21 $ 1,783 $ 14 — $ 4,703 Unpaid principal $ 1,382 $ 640 $ 440 $ 443 $ 22 $ 1,842 $ 14 — $ 4,783 Related allowance $ 172 $ 18 $ 106 $ 57 $ 14 $ 811 $ 14 — $ 1,192 Average recorded investment $ 1,692 $ 1,029 $ 1,076 $ 557 $ 11 $ 1,938 $ 7 — $ 6,310 Interest income recognized $ 11 $ 9 $ 1 $ 5 — $ 14 — — $ 40 Impaired PNCI Loans – As of, or for the Three Months Ended, March 31, 2017 RE Mortgage Home Equity Other Construction (in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total With no related allowance recorded: Recorded investment $ 433 $ 1,777 $ 220 $ 58 $ 138 — — — $ 2,626 Unpaid principal $ 455 $ 2,011 $ 233 $ 67 $ 139 — — — $ 2,905 Average recorded investment $ 654 $ 1,455 $ 337 $ 64 $ 86 $ 1 — $ 245 $ 2,842 Interest income recognized $ 2 — $ 1 — $ 2 — — — $ 5 With an allowance recorded: Recorded investment $ 256 $ 131 $ 493 — $ 116 — — — $ 996 Unpaid principal $ 256 $ 131 $ 493 — $ 116 — — — $ 996 Related allowance $ 77 $ 106 $ 295 — $ 16 — — — $ 494 Average recorded investment $ 128 $ 1,440 $ 550 $ 19 $ 175 — — — $ 2,312 Interest income recognized $ 2 $ 2 $ 5 — $ 1 — — — $ 10
Troubled Debt Restructurings	The following table shows certain information regarding TDRs that occurred during the period indicated: TDR Information for the Three Months Ended March 31, 2018 RE Mortgage Home Equity Other Construction (dollars in thousands) Resid. Comm. Lines Loans Consum. C&I Resid. Comm. Total Number — 1 1 1 — — — — 3 Pre-mod — $ 384 $ 133 $ 121 — — — — $ 638 Post-mod — $ 384 $ 138 $ 121 — — — — $ 643 Financial impact due to TDR taken as additional provision — $ 11 — — — — — — $ 11 Number that defaulted during the period — 1 — — — — — — 1 Recorded investment of TDRs that defaulted during the period — $ 169 — — — — — — $ 169 Financial impact due to the default of previous TDR taken as charge-offs or additional provisions — — — — — — — — — The following table shows certain information regarding TDRs that occurred during the period indicated: TDR Information for the Year Ended December 31, 2017 RE Mortgage Home Equity Other Construction (dollars in thousands) Resid. Comm. Lines Loans 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 defaulted during the period $ 223 $ 219 $ 127 $ 55 — — — — $ 624 Financial impact due to the default of previous TDR taken as charge-offs or additional provisions — — $ (5 ) — — — — — $ (5 )

Foreclosed Assets (Tables)

Foreclosed Assets (Tables)	3 Months Ended
	Mar. 31, 2018
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): Three months ended Three months ended March 31, 2017 Total Noncovered Covered Total Beginning balance, net $ 3,226 $ 3,763 $ 223 $ 3,986 Additions/transfers from loans — 85 — 85 Dispositions/sales (1,572 ) (385 ) (223 ) (608 ) Valuation adjustments (90 ) 66 — 66 Ending balance, net $ 1,564 $ 3,529 — $ 3,529 Ending valuation allowance $ (152 ) $ (300 ) — $ (300 ) Ending number of foreclosed assets 10 12 — 12 Proceeds from sale of foreclosed assets $ 1,943 $ 510 $ 216 $ 726 Gain (loss) on sale of foreclosed assets $ 371 $ 125 $ (7 ) $ 118

Premises and Equipment (Tables)

Premises and Equipment (Tables)	3 Months Ended
	Mar. 31, 2018
Property, Plant and Equipment [Abstract]
Summary of Premises and Equipment	Premises and equipment were comprised of: March 31, December 31, (In thousands) Land & land improvements $ 9,959 $ 9,959 Buildings 50,792 50,340 Furniture and equipment 37,348 35,939 98,099 96,238 Less: Accumulated depreciation (41,678 ) (40,644 ) 56,421 55,594 Construction in progress 2,137 2,148 Total premises and equipment $ 58,558 $ 57,742

Cash Value of Life Insurance (T

Cash Value of Life Insurance (Tables)	3 Months Ended
	Mar. 31, 2018
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): Three months ended March 31, 2018 2017 Beginning balance $ 97,783 $ 95,912 Increase in cash value of life insurance 608 685 Gain on death benefit — 107 Insurance proceeds receivable reclassified to other assets — (921 ) Ending balance $ 98,391 $ 95,783 End of period death benefit $ 159,640 $ 164,574 Number of policies owned 182 183 Insurance companies used 14 14 Current and former employees and directors covered 57 58

Goodwill and Other Intangible46

Goodwill and Other Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Goodwill Intangible	The following table summarizes the Company’s goodwill intangible as of the dates indicated: (in thousands) March 31, Additions Reductions December 31, 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: (in thousands) March 31, Additions Reductions/ December 31, Core deposit intangibles $ 9,558 — — $ 9,558 Accumulated amortization (4,723 ) — $ (339 ) (4,384 ) Core deposit intangibles, net $ 4,835 — $ (339 ) $ 5,174
Remaining Estimated Core Deposit Intangible Amortization	The following table summarizes the Company’s remaining estimated core deposit intangible amortization (in thousands): Years Ended Estimated Core Deposit 2018 $ 1,324 2019 1,228 2020 1,228 2021 969 2022 280 Thereafter 145

Mortgage Servicing Rights (Tabl

Mortgage Servicing Rights (Tables)	3 Months Ended
	Mar. 31, 2018
Text Block [Abstract]
Fair Value of Mortgage Servicing Rights	The following tables summarize the activity in, and the main assumptions used to determine the fair value of mortgage servicing rights (“MSRs”) for the periods indicated (dollars in thousands): Three months ended March 31, 2018 2017 Balance at beginning of period $ 6,687 $ 6,595 Additions 155 278 Change in fair value 111 (13 ) Balance at end of period $ 6,953 $ 6,860 Contractually specified servicing fees, late fees and ancillary fees earned $ 517 $ 521 Balance of loans serviced at: Beginning of period $ 811,065 $ 816,623 End of period $ 806,478 $ 822,506 Weighted-average prepayment speed (CPR) 7.5 % 8.3 % Weighted-average discount rate 13.0 % 14.0 %

Indemnification Asset (Tables)

Indemnification Asset (Tables)	3 Months Ended
	Mar. 31, 2018
Text Block [Abstract]
Summary of Activity in Balance of Indemnification Asset	A summary of the activity in the balance of indemnification asset follows (in thousands): Three months ended March 31, 2018 2017 Beginning balance — $ (744 ) Effect of actual and estimated future covered losses and recoveries — (191 ) Reimbursable (revenue) expenses incurred — (32 ) Payments made to (received from) FDIC — 72 Ending balance — $ (895 ) Amount of indemnification liability recorded in other assets — $ (179 ) Amount of indemnification liability recorded in other liabilities — (716 ) Ending balance — $ (895 )

Other Assets (Tables)

Other Assets (Tables)	3 Months Ended
	Mar. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Summary of Other Assets	Other assets were comprised of (in thousands): March 31, December 31, Deferred tax asset, net $ 26,266 $ 21,697 Investment in low income housing tax credit funds 17,095 16,854 Prepaid expense 4,411 4,111 Tax refund receivable 4,754 4,754 Capital trusts 1,709 1,706 Software 883 1,126 Life insurance proceeds receivable — 2,242 Miscellaneous other assets 1,156 2,561 Total other assets $ 56,274 $ 55,051

Deposits (Tables)

Deposits (Tables)	3 Months Ended
	Mar. 31, 2018
Banking and Thrift [Abstract]
Summary of Balances of Deposits	A summary of the balances of deposits follows (in thousands): March 31, December 31, Noninterest-bearing demand $ 1,359,996 $ 1,368,218 Interest-bearing demand 1,022,299 971,459 Savings 1,395,481 1,364,518 Time certificates, over $250,000 76,306 73,596 Other time certificates 230,322 231,340 Total deposits $ 4,084,404 $ 4,009,131

Reserve for Unfunded Commitme51

Reserve for Unfunded Commitments (Tables)	3 Months Ended
	Mar. 31, 2018
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 (in thousands): Three months ended March 31, 2018 2017 Balance at beginning of period $ 3,164 $ 2,719 Provision for losses – unfunded commitments 700 15 Balance at end of period $ 3,864 $ 2,734

Other Liabilities (Tables)

Other Liabilities (Tables)	3 Months Ended
	Mar. 31, 2018
Other Liabilities Disclosure [Abstract]
Components of Other Liabilities	Other liabilities were comprised of (in thousands): March 31, December 31, Pension liability $ 28,686 $ 28,472 Low income housing tax credit fund commitments 7,677 8,554 Deferred compensation 6,809 6,605 Taxes payable 5,243 — Accrued salaries and benefits expense 5,180 6,619 Joint beneficiary agreements 3,429 3,365 Loan escrow and servicing payable 1,464 1,958 Deferred revenue 1,077 1,228 Litigation contingency — 1,450 Miscellaneous other liabilities 3,964 5,007 Total other liabilities $ 63,529 $ 63,258

Other Borrowings (Tables)

Other Borrowings (Tables)	3 Months Ended
	Mar. 31, 2018
Text Block [Abstract]
Summary of Balances of Other Borrowings	A summary of the balances of other borrowings follows: March 31, December 31, (in thousands) FHLB collateralized borrowing, fixed rate, as of March 31, 2018 of 1.87%, payable on April 2, 2018 $ 48,000 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 March 31, 2018 and December 31, 2017 of 0.05%, payable on April 2, 2018 and January 2, 2018, respectively 17,041 17,437 Total other borrowings $ 65,041 $ 122,166

Junior Subordinated Debt (Table

Junior Subordinated Debt (Tables)	3 Months Ended
	Mar. 31, 2018
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): Subordinated Debt Series Coupon Rate As of March 31, 2018 December 31, 2017 Maturity Face (Variable) Current Recorded Recorded Date Value 3 mo. LIBOR + Coupon Rate Book Value Book Value TriCo Cap Trust I 10/7/2033 $ 20,619 3.05 % 4.77 % $ 20,619 $ 20,619 TriCo Cap Trust II 7/23/2034 20,619 2.55 % 4.29 % 20,619 20,619 North Valley Trust II 4/24/2033 6,186 3.25 % 5.02 % 5,145 5,135 North Valley Trust III 4/24/2034 5,155 2.80 % 4.54 % 4,050 4,041 North Valley Trust IV 3/15/2036 10,310 1.33 % 3.45 % 6,472 6,444 $ 62,889 $ 56,905 $ 56,858

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2018
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 Company's Commitments and Contingent Liabilities	The following table presents a summary of the Company’s commitments and contingent liabilities: (in thousands) March 31, December 31, Financial instruments whose amounts represent risk: Commitments to extend credit: Commercial loans $ 253,001 $ 257,220 Consumer loans 437,790 422,958 Real estate mortgage loans 73,618 66,267 Real estate construction loans 236,650 187,097 Standby letters of credit 11,573 13,075 Deposit account overdraft privilege 101,411 98,260

Stock Options and Other Equit56

Stock Options and Other Equity-Based Incentive Instruments (Tables)	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Option Activity	Stock option activity during the three months ended March 31, 2018 is summarized in the following table: Number Option Price per Share Weighted Value on Weighted Outstanding at December 31, 2017 446,400 $ 12.63 to $23.21 $ 16.84 Options granted — — to — — Options exercised — — to — — Options forfeited — — to — — Outstanding at March 31, 2018 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 March 31, 2018: Currently Currently Not Total Exercisable Exercisable Outstanding Number of options 423,600 22,800 446,400 Weighted average exercise price $ 16.65 $ 20.45 $ 16.84 Intrinsic value (in thousands) $ 8,713 $ 382 $ 9,096 Weighted average remaining contractual term (yrs.) 3.6 5.5 3.7
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, 2017 68,457 52,829 RSUs granted — — RSUs added through dividend credits 310 — RSUs released (494 ) — RSUs forfeited/expired — — Outstanding at March 31, 2018 68,273 52,829

Noninterest Income and Expense

Noninterest Income and Expense (Tables)	3 Months Ended
	Mar. 31, 2018
Other Income and Expenses [Abstract]
Components of Other Noninterest Income	The components of other noninterest income were as follows (in thousands): Three months ended March 31, 2018 2017 Service charges on deposit accounts $ 3,779 $ 3,619 ATM and interchange fees 4,235 4,015 Other service fees 714 765 Mortgage banking service fees 517 521 Change in value of mortgage servicing rights 111 (13 ) Total service charges and fees 9,356 8,907 Commissions on sale of non-deposit 876 607 Gain on sale of loans 626 910 Increase in cash value of life insurance 608 685 Gain on sale of foreclosed assets 371 118 Lease brokerage income 128 206 Sale of customer checks 101 104 Change in indemnification asset — (221 ) Life insurance proceeds in excess of cash value — 107 Loss on disposal of fixed assets (13 ) — Loss on marketable equity securities (47 ) — Other 284 280 Total other noninterest income 2,934 2,796 Total noninterest income $ 12,290 $ 11,703
Components of Noninterest Expense	The components of noninterest expense were as follows (in thousands): Three months ended March 31, 2018 2017 Base salaries, net of deferred loan origination costs $ 13,962 $ 13,390 Incentive compensation 2,452 2,198 Benefits and other compensation costs 5,238 5,305 Total salaries and benefits expense 21,652 20,893 Occupancy 2,681 2,692 Data processing and software 2,514 2,396 Equipment 1,551 1,723 ATM and POS network charges 1,226 853 Advertising 838 967 Professional fees 773 766 Telecommunications 701 643 Change in reserve for unfunded commitments 700 15 Merger and acquisition expense 476 — Assessments 430 405 Postage 358 404 Intangible amortization 339 359 Operational losses 294 435 Courier service 267 254 Provision for (reversal of) foreclosed asset losses 90 (66 ) Foreclosed assets expense 24 38 Other miscellaneous expense 3,248 3,045 Total other noninterest expense 16,510 14,929 Total noninterest expense $ 38,162 $ 35,822 Merger and acquisition expense: Professional fees $ 355 — Advertising and marketing 8 — Other miscellaneous expense 112 — Total merger and acquisition expense $ 476 —

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Reconciliation of Effective Tax Rate and Statutory Federal Income Tax Rate	The effective tax rate and the statutory federal income tax rate are reconciled for the periods indicated as follows: Three months ended March 31, 2018 2017 Federal statutory income tax rate 21.0 % 35.0 % State income taxes, net of federal tax benefit 9.0 6.9 Tax-exempt (1.1 ) (1.9 ) Increase in cash value of insurance policies (0.7 ) (1.4 ) Low income housing tax credits (1.0 ) (0.6 ) Equity compensation — (0.5 ) Nondeductible merger expenses 0.4 — Nondeductible joint beneficiary agreement expense 0.1 0.1 Other 0.4 0.2 Effective Tax Rate 28.1 % 37.8 %

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Computation of Earnings Per Share	Earnings per share have been computed based on the following: Three months ended March 31, (in thousands) 2018 2017 Net income $ 13,910 $ 12,079 Average number of common shares outstanding 22,956 22,870 Effect of dilutive stock options and restricted stock 327 362 Average number of common shares outstanding used to calculate diluted earnings per share 23,283 23,232 Options excluded from diluted earnings per share because the effect of these options was antidilutive — —

Comprehensive Income (Tables)

Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Components of Other Comprehensive Income and Related Tax Effects	The components of other comprehensive income and related tax effects are as follows: Three months ended March 31, (in thousands) 2018 2017 Unrealized holding gains (losses) on available for sale securities before reclassifications $ (15,265 ) $ 787 Amounts reclassified out of accumulated other comprehensive income: Adoption ASU 2016-01 62 — Adoption ASU 2018-02 (425 ) — Total amounts reclassified out of accumulated other comprehensive income (363 ) — Unrealized holding gains (losses) on available for sale securities after reclassifications (15,628 ) 787 Tax effect 4,602 (330 ) Unrealized holding gains (losses) on available for sale securities, net of tax (11,026 ) 457 Change in unfunded status of the supplemental retirement plans before reclassifications 667 — Amounts reclassified out of accumulated other comprehensive income: Amortization of prior service cost (13 ) (3 ) Amortization of actuarial losses 127 96 Adoption ASU 2018-02 (668 ) — Total amounts reclassified out of accumulated other comprehensive income (554 ) 93 Change in unfunded status of the supplemental retirement plans after reclassifications 113 93 Tax effect (33 ) (39 ) Change in unfunded status of the supplemental retirement plans, net of tax 80 54 Change in joint beneficiary agreement liability before reclassifications — — Amounts reclassified out of accumulated other comprehensive income — — Change in joint beneficiary agreement liability after reclassifications — — Tax effect — — Change in joint beneficiary agreement liability, net of tax — — Total other comprehensive income (loss) $ (10,946 ) $ 511
Components of Accumulated Other Comprehensive Income	The components of accumulated other comprehensive income, included in shareholders’ equity, are as follows: Three months ended March 31, (in thousands) 2018 2017 Net unrealized loss on available for sale securities $ (18,975 ) $ (8,083 ) Tax effect 5,610 3,399 Unrealized holding loss on available for sale securities, net of tax (13,365 ) (4,684 ) Unfunded status of the supplemental retirement plans (5,238 ) (4,621 ) Tax effect 1,549 1,943 Unfunded status of the supplemental retirement plans, net of tax (3,689 ) (2,678 ) Joint beneficiary agreement liability (151 ) (40 ) Tax effect — — Joint beneficiary agreement liability, net of tax (151 ) (40 ) Accumulated other comprehensive loss $ (17,205 ) $ (7,402 )

Retirement Plans (Tables)

Retirement Plans (Tables)	3 Months Ended
	Mar. 31, 2018
Retirement Benefits [Abstract]
Net Periodic Benefit Cost Recognized for Supplemental Retirement Plans	The following table sets forth the net periodic benefit cost recognized for the plans: Three months ended March 31, 2018 2017 (in thousands) Net pension cost included the following components: Service cost-benefits earned during the period $ 243 $ 235 Interest cost on projected benefit obligation 237 249 Amortization of net obligation at transition 1 1 Amortization of prior service cost (13 ) (3 ) Recognized net actuarial loss 127 96 Net periodic pension cost $ 595 $ 578

Related Party Transactions (Tab

Related Party Transactions (Tables)	3 Months Ended
	Mar. 31, 2018
Related Party Transactions [Abstract]
Summary of Activity in Lending Transactions	The following table summarizes the activity in these loans for periods indicated (in thousands): Balance December 31, 2016 $ 2,432 Advances/new loans 437 Removed/payments (721 ) Balance December 31, 2017 2,148 Advances/new loans 145 Removed/payments (314 ) Balance March 31, 2018 $ 1,979

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	3 Months Ended
	Mar. 31, 2018
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): Fair value at March 31, 2018 Total Level 1 Level 2 Level 3 Marketable equity securities $ 2,890 $ 2,890 $ — $ — Debt securities available for sale: Obligations of U.S. government corporations and agencies 616,657 — 616,657 — Obligations of states and political subdivisions 119,238 — 119,238 — Mortgage servicing rights 6,953 — — 6,953 Total assets measured at fair value $ 745,738 $ 2,890 $ 735,895 $ 6,953 Fair value at December 31, 2017 Total Level 1 Level 2 Level 3 Marketable equity securities $ 2,938 $ 2,938 $ — $ — Debt 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 — Mortgage servicing rights 6,687 — — 6,687 Total assets measured at fair value $ 737,570 $ 2,938 $ 727,945 $ 6,687
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 time periods indicated. Had there been any transfer into or out of Level 3 during the time periods indicated, 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): Three months ended March 31, Beginning Transfers Change Issuances Ending 2018: Mortgage servicing rights $ 6,687 — $ 111 $ 155 $ 6,953 2017: Mortgage servicing rights $ 6,595 — $ (13 ) $ 278 $ 6,860
Quantitative Information about Recurring Level 3 Fair Value Measurements	The following table presents quantitative information about recurring Level 3 fair value measurements at March 31, 2018: Fair Value Valuation Unobservable Range, Mortgage Servicing Rights $ 6,953 Discounted cash flow Constant prepayment rate 6.0%-19.7%, 7.5 % Discount rate 11.0%-15.0%, 13.0% The following table presents quantitative information about recurring Level 3 fair value measurements at December 31, 2017: Fair Value Valuation Unobservable Range, Mortgage Servicing Rights $ 6,687 Discounted cash flow Constant prepayment rate 6.2%-22.0%, 8.9 %
Assets and Liabilities Measured at Fair Value on Nonrecurring Basis	The tables below present the recorded investment in assets and liabilities measured at fair value on a nonrecurring basis, as of the dates indicated (in thousands): Three months ended March 31, 2018 Total Level 1 Level 2 Level 3 Total Gains Fair value: Impaired Originated & PNCI loans $ 2,103 — — $ 2,103 $ (795 ) Foreclosed assets 774 — — 774 (87 ) Total assets measured at fair value $ 2,877 — — $ 2,877 $ (882 ) Year ended December 31, 2017 Total Level 1 Level 2 Level 3 Total Gains 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 ) Three months ended March 31, 2017 Total Level 1 Level 2 Level 3 Total Gains Fair value: Impaired Originated & PNCI loans $ 824 — — $ 824 $ 30 Foreclosed assets 1,528 — — 1,528 (22 ) Total assets measured at fair value $ 2,352 — — $ 2,352 $ 8
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 March 31, 2018: March 31, 2018 Fair Value Valuation Technique Unobservable Inputs Range, Impaired Originated & PNCI loans $ 2,103 Sales comparison Income approach Adjustment for differences Not meaningful Foreclosed assets (Land & construction) $ 190 Sales comparison Adjustment for differences Not meaningful Foreclosed assets (Residential real estate) $ 492 Sales comparison Adjustment for differences Not meaningful Foreclosed assets (Commercial real estate) $ 92 Sales comparison Adjustment for differences Not meaningful 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: December 31, 2017 Fair Value Valuation Unobservable Inputs Range, Impaired Originated & PNCI loans $ 2,767 Sales comparison Adjustment for differences Not meaningful Foreclosed assets (Land & construction) $ 1,341 Sales comparison Adjustment for differences Not meaningful Foreclosed assets (Residential real estate) $ 622 Sales comparison Adjustment for differences Not meaningful Foreclosed assets (Commercial real estate) $ 254 Sales comparison Adjustment for differences 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 Company’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): March 31, 2018 December 31, 2017 Carrying Fair Carrying Fair Financial assets: Level 1 inputs: Cash and due from banks $ 87,138 $ 87,138 $ 105,968 $ 105,968 Cash at Federal Reserve and other banks 95,841 95,841 99,460 99,460 Level 2 inputs: Securities held to maturity 496,035 488,639 514,844 518,165 Restricted equity securities 16,956 N/A 16,956 N/A Loans held for sale 2,149 2,149 4,616 4,616 Level 3 inputs: Loans, net 3,039,760 3,025,636 2,984,842 2,992,225 Financial liabilities: Level 2 inputs: Deposits 4,084,404 4,081,089 4,009,131 4,006,620 Other borrowings 65,041 65,041 122,166 122,166 Level 3 inputs: Junior subordinated debt 56,905 59,982 56,858 58,466 Contract Fair Contract Fair Off-balance Level 3 inputs: Commitments $ 1,001,059 $ 10,011 $ 933,542 $ 9,335 Standby letters of credit 11,573 116 13,075 131 Overdraft privilege commitments 101,411 1,014 98,260 983

TriCo Bancshares Condensed Fi64

TriCo Bancshares Condensed Financial Statements (Parent Only) (Tables)	3 Months Ended
	Mar. 31, 2018
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Balance Sheets	Condensed Balance Sheets March 31, December 31, (In thousands) Assets Cash and cash equivalents $ 3,516 $ 3,924 Investment in Tri Counties Bank 557,380 557,538 Other assets 1,758 1,721 Total assets $ 562,654 $ 563,183 Liabilities and shareholders’ equity Other liabilities $ 493 $ 517 Junior subordinated debt 56,905 56,858 Total liabilities 57,398 57,375 Shareholders’ equity: Preferred stock, no par value: 1,000,000 shares authorized, zero issued and outstanding at March 31, 2018 and December 31, 2017 — — Common stock, no par value: authorized 50,000,000 shares; issued and outstanding 22,956,323 and 22,955,963 shares, respectively 256,226 255,836 Retained earnings 266,235 255,200 Accumulated other comprehensive loss, net (17,205 ) (5,228 ) Total shareholders’ equity 505,256 505,808 Total liabilities and shareholders’ equity $ 562,654 $ 563,183
Condensed Statements of Income	Condensed Statements of Income Three months ended March 31, 2018 2017 (In thousands) Interest expense $ (697 ) $ (595 ) Administration expense (426 ) (159 ) Loss before equity in net income of Tri Counties Bank (1,123 ) (754 ) Equity in net income of Tri Counties Bank: Distributed 4,372 4,042 Undistributed 10,397 8,474 Income tax benefit 264 317 Net income $ 13,910 $ 12,079
Condensed Statements of Comprehensive Income	Condensed Statements of Comprehensive Income Three months ended March 31, 2018 2017 (In thousands) Net income $ 13,910 $ 12,079 Other comprehensive income (loss), net of tax: Increase (decrease) in unrealized gains on available for sale securities arising during the period (11,026 ) 457 Change in minimum pension liability 80 54 Other comprehensive income (loss) (10,946 ) 511 Comprehensive income $ 2,964 $ 12,590
Condensed Statements of Cash Flows	Condensed Statements of Cash Flows Three months ended March 31, 2018 2017 (In thousands) Operating activities: Net income $ 13,910 $ 12,079 Adjustments to reconcile net income to net cash provided by operating activities: Undistributed equity in earnings of Tri Counties Bank (10,397 ) (8,474 ) Equity compensation vesting expense 391 381 Stock option excess tax benefits — Net change in other assets and liabilities (405 ) (348 ) Net cash provided by operating activities 3,499 3,638 Investing activities: None Financing activities: Repurchase of common stock (4 ) (169 ) Cash dividends paid — common (3,903 ) (3,431 ) Net cash used for financing activities (3,907 ) (3,600 ) Net change in cash and cash equivalents (408 ) 38 Cash and cash equivalents at beginning of year 3,924 2,802 Cash and cash equivalents at end of year $ 3,516 $ 2,840

Regulatory Matters (Tables)

Regulatory Matters (Tables)	3 Months Ended
	Mar. 31, 2018
Banking and Thrift [Abstract]
Actual and Required Capital Ratios of Bank	The following tables present actual and required capital ratios as of March 31, 2018 and December 31, 2017 for the Company and the Bank under Basel III Capital Rules. The minimum capital amounts presented include the minimum required capital levels as of March 31, 2018 (1.875%) and December 31, 2017 (1.25%) based on the then phased-in phased-in. Minimum Capital Minimum Capital Required to be Required – Basel III Required – Basel III Considered Well Actual Phase-in Fully Phased In Capitalized Amount Ratio Amount Ratio Amount Ratio Amount Ratio (dollars in thousands) As of March 31, 2018: Total Capital (to Risk Weighted Assets): Consolidated $539,966 13.91 % $ 383,434 9.875 % $ 407,702 10.50 % N/A N/A Tri Counties Bank $536,894 13.83 % $ 383,261 9.875 % $ 407,518 10.50 % $ 388,112 10.00 % Tier 1 Capital (to Risk Weighted Assets): Consolidated $506,129 13.03 % $ 305,777 7.875 % $ 330,045 8.50 % N/A N/A Tri Counties Bank $503,057 12.96 % $ 305,638 7.875 % $ 329,895 8.50 % $ 310,490 8.00 % Common equity Tier 1 Capital (to Risk Weighted Assets): Consolidated $450,933 11.61 % $ 247,534 6.375 % $ 271,802 7.00 % N/A N/A Tri Counties Bank $503,057 12.96 % $ 247,421 6.375 % $ 271,678 7.00 % $ 252,273 6.50 % Tier 1 Capital (to Average Assets): Consolidated $506,129 10.84 % $ 186,720 4.000 % $ 186,720 4.00 % N/A N/A Tri Counties Bank $503,057 10.78 % $ 186,716 4.000 % $ 186,716 4.00 % $ 233,395 5.00 % 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 9.25 % $ 394,679 10.50 % N/A N/A Tri Counties Bank $ 525,384 13.98 % $ 347,535 9.25 % $ 394,499 10.50 % $ 375,713 10.00 % Tier 1 Capital (to Risk Weighted Assets): Consolidated $ 495,318 13.18 % $ 272,517 7.25 % $ 319,502 8.50 % N/A N/A Tri Counties Bank $ 491,897 13.09 % $ 272,392 7.25 % $ 319,356 8.50 % $ 300,570 8.00 % Common equity Tier 1 Capital (to Risk Weighted Assets): Consolidated $ 440,643 11.72 % $ 216,134 5.75 % $ 263,120 7.00 % N/A N/A Tri Counties Bank $ 491,897 13.09 % $ 216,035 5.75 % $ 262,999 7.00 % $ 244,214 6.50 % Tier 1 Capital (to Average Assets): Consolidated $ 495,318 10.80 % $ 183,400 4.00 % $ 183,400 4.00 % N/A N/A Tri Counties Bank $ 491,897 10.73 % $ 183,394 4.00 % $ 183,394 4.00 % $ 229,243 5.00 %

Summary of Quarterly Results 66

Summary of Quarterly Results of Operations (unaudited) (Tables)	3 Months Ended
	Mar. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Results of Operations	The following table sets forth the results of operations for the periods indicated, 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. 2018 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 $ 246 Discount accretion PCI – other 60 Discount accretion PNCI 326 All other loan interest income 37,417 Total loan interest income 38,049 Debt securities, dividends and interest bearing cash at banks (not FTE) 9,072 Total interest income 47,121 Interest expense 2,135 Net interest income 44,986 (Benefit from reversal of) provision for loan losses (236 ) Net interest income after provision for loan losses 45,222 Noninterest income 12,290 Noninterest expense 38,162 Income before income taxes 19,350 Income tax expense 5,440 Net income $ 13,910 Per common share: Net income (diluted) $ 0.60 Dividends $ 0.17 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

Summary of Significant Accoun67

Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended		12 Months Ended
	Mar. 31, 2018USD ($)OfficeSegmentLocationTrustBranchBusiness	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)	Jan. 01, 2018USD ($)
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	$ 1,703,000
Number of business segment | Segment	1
Marketable securities recorded	$ 2,890,000		$ 2,938,000
Unrealized losses recognized in condensed consolidated statements of income	48,000
OTTI losses due to debt securities	$ 0		$ 0
Loans contractual past due	90 days
TDR loans payment period in nonaccrual status	6 months
Federal statutory income tax rate	21.00%	35.00%	35.00%
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
Trading Debt Securities [Member]
Significant Of Accounting Policies [Line Items]
Trading debt securities	$ 0		$ 0
California [Member]
Significant Of Accounting Policies [Line Items]
Number of counties | Business	26
ASU 2016-01 [Member] | Deferred Tax Assets [Member]
Significant Of Accounting Policies [Line Items]
New accounting pronouncement or change in accounting principle cumulative effect of change on equity or net assets				$ (18,000)
ASU 2016-01 [Member] | Retained Earnings [Member]
Significant Of Accounting Policies [Line Items]
New accounting pronouncement or change in accounting principle cumulative effect of change on equity or net assets				(62,000)
ASU 2016-09 [Member]
Significant Of Accounting Policies [Line Items]
Recognition of excess tax benefits		$ 90,000
ASU 2018-02 [Member] | Retained Earnings [Member]
Significant Of Accounting Policies [Line Items]
New accounting pronouncement or change in accounting principle cumulative effect of change on equity or net assets				1,093,000
ASU 2018-02 [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Significant Of Accounting Policies [Line Items]
New accounting pronouncement or change in accounting principle cumulative effect of change on equity or net assets				$ (1,093,000)
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) - USD ($) $ / shares in Units, $ in Millions	Dec. 11, 2017	Dec. 08, 2017
Business Acquisition [Line Items]
Common stock, closing price		$ 41.64
Merger Agreement [Member] | FNBB [Member]
Business Acquisition [Line Items]
Ownership percentage of combined entity post merger		24.00%
FNBB [Member]
Business Acquisition [Line Items]
Consideration value, per share		$ 40.81
Total consideration value		$ 315.3
FNBB [Member] | Merger Agreement [Member]
Business Acquisition [Line Items]
Average share price of the Company's Stock, percentage	120.00%
Initial price	$ 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	$ 49.78
FNBB [Member] | Merger Agreement [Member] | Maximum [Member]
Business Acquisition [Line Items]
Consideration value, per share	$ 33.18
Number of trading days	20 days
Shares held by acquiree	$ 119
FNBB [Member] | Common Stock [Member]
Business Acquisition [Line Items]
Shares exchange ratio	0.98

Investment Securities - Amortiz

Investment Securities - Amortized Cost and Estimated Fair Values of Investments in Debt Securities (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 754,870	$ 731,292
Gross Unrealized Gains	783	2,583
Gross Unrealized Losses	(19,758)	(5,930)
Estimated Fair Value	735,895	727,945
Amortized Cost, Held to Maturity	496,035	514,844
Gross Unrealized Gains, Held to Maturity	572	5,247
Gross Unrealized Losses, Held to Maturity	(7,968)	(1,926)
Estimated Fair Value, Held to Maturity	488,639	518,165
Obligations of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	633,310	609,695
Gross Unrealized Gains	317	695
Gross Unrealized Losses	(16,970)	(5,601)
Estimated Fair Value	616,657	604,789
Amortized Cost, Held to Maturity	481,457	500,271
Gross Unrealized Gains, Held to Maturity	533	5,101
Gross Unrealized Losses, Held to Maturity	(7,737)	(1,889)
Estimated Fair Value, Held to Maturity	474,253	503,483
Obligations of States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	121,560	121,597
Gross Unrealized Gains	466	1,888
Gross Unrealized Losses	(2,788)	(329)
Estimated Fair Value	119,238	123,156
Amortized Cost, Held to Maturity	14,578	14,573
Gross Unrealized Gains, Held to Maturity	39	146
Gross Unrealized Losses, Held to Maturity	(231)	(37)
Estimated Fair Value, Held to Maturity	$ 14,386	$ 14,682

Investment Securities - Additio

Investment Securities - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2018USD ($)Investmentsecurities	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)
Investment Securities [Line Items]
Investment securities sold	$ 0	$ 0
Investment securities carrying value	415,542,000		$ 285,596,000
Residential real estate mortgage-backed securities	$ 1,114,767,000
Life of mortgage-backed securities	6 years 1 month 6 days
Obligations of U.S. Government Corporations and Agencies [Member]
Investment Securities [Line Items]
Debt securities | Investmentsecurities	128
Percentage of aggregate depreciation in unrealized losses	2.45%
Obligations of States and Political Subdivisions [Member]
Investment Securities [Line Items]
Debt securities | Investmentsecurities	94
Percentage of aggregate depreciation in unrealized losses	3.16%

Investment Securities - Amort71

Investment Securities - Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Due in one year, Amortized Cost	$ 2
Due after one year through five years, Amortized Cost	235
Due after five years through ten years, Amortized Cost	3,324
Due after ten years, Amortized Cost	751,309
Totals, Amortized Cost	754,870
Due in one year, Estimated Fair Value	2
Due after one year through five years, Estimated Fair Value	236
Due after five years through ten years, Estimated Fair Value	3,452
Due after ten years, Estimated Fair Value	732,205
Totals, Estimated Fair Value	735,895
Due in one year, Amortized Cost, Held to Maturity	0
Due after one year through five years, Amortized Cost, Held to Maturity	1,215
Due after five years through ten years, Amortized Cost, Held to Maturity	20,631
Due after ten years, Amortized Cost, Held to Maturity	474,189
Totals, Amortized Cost, Held to Maturity	496,035	$ 514,844
Due in one year, Estimated Fair Value, Held to Maturity	0
Due after one year through five years, Estimated Fair Value, Held to Maturity	1,228
Due after five years through ten years, Estimated Fair Value, Held to Maturity	20,291
Due after ten years, Estimated Fair Value, Held to Maturity	467,120
Estimated Fair Value, Held to Maturity	$ 488,639	$ 518,165

Investment Securities - Gross U

Investment Securities - Gross Unrealized Losses on Debt Securities (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	$ 499,349	$ 289,271
Less than 12 months, Unrealized Loss	(11,801)	(2,211)
12 months or more, Fair Value	174,366	183,423
12 months or more, Unrealized Loss	(7,957)	(3,719)
Total Fair Value	673,715	472,694
Total Unrealized Loss	(19,758)	(5,930)
Less than 12 months, Fair Value, held to maturity	308,476	94,505
Less than 12 months, Unrealized Loss, held to maturity	(4,695)	(574)
12 months or more, Fair Value, held to maturity	92,388	98,004
12 months or more, Unrealized Loss, held to maturity	(3,273)	(1,352)
Total Fair Value, held to maturity	400,864	192,509
Total Unrealized Loss, held to maturity	(7,968)	(1,926)
Obligations of U.S. Government Corporations and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	434,302	284,367
Less than 12 months, Unrealized Loss	(10,345)	(2,176)
12 months or more, Fair Value	158,324	166,338
12 months or more, Unrealized Loss	(6,625)	(3,425)
Total Fair Value	592,626	450,705
Total Unrealized Loss	(16,970)	(5,601)
Less than 12 months, Fair Value, held to maturity	299,575	93,017
Less than 12 months, Unrealized Loss, held to maturity	(4,551)	(567)
12 months or more, Fair Value, held to maturity	89,809	95,367
12 months or more, Unrealized Loss, held to maturity	(3,186)	(1,322)
Total Fair Value, held to maturity	389,384	188,384
Total Unrealized Loss, held to maturity	(7,737)	(1,889)
Obligations of States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	65,047	4,904
Less than 12 months, Unrealized Loss	(1,456)	(35)
12 months or more, Fair Value	16,042	17,085
12 months or more, Unrealized Loss	(1,332)	(294)
Total Fair Value	81,089	21,989
Total Unrealized Loss	(2,788)	(329)
Less than 12 months, Fair Value, held to maturity	8,901	1,488
Less than 12 months, Unrealized Loss, held to maturity	(144)	(7)
12 months or more, Fair Value, held to maturity	2,579	2,637
12 months or more, Unrealized Loss, held to maturity	(87)	(30)
Total Fair Value, held to maturity	11,480	4,125
Total Unrealized Loss, held to maturity	$ (231)	$ (37)

Loans - Summary of Loan Balance

Loans - Summary of Loan Balances (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	$ 3,069,733	$ 3,015,165	$ 2,761,192
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	3,069,733	3,015,165	2,761,192
Construction:
Total loans, net of unamortized deferred loan fees and discounts	3,069,733	3,015,165	2,761,192
Commercial	3,093,564	3,038,472
Unamortized net deferred loan fees	(9,671)	(8,651)
Discounts to principal balance of loans owed, net of charge-offs	(14,160)	(14,656)
Total loans, net of unamortized deferred loan fees and discounts	3,069,733	3,015,165	2,761,192
Allowance for loan losses	(29,973)	(30,323)	(31,017)	$ (32,503)
Mortgage Loans on Real Estate [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	2,359,379	2,300,322
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	2,359,379	2,300,322
Construction:
Total loans, net of unamortized deferred loan fees and discounts	2,359,379	2,300,322
Total loans, net of unamortized deferred loan fees and discounts	2,359,379	2,300,322
Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	348,789	356,874
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	348,789	356,874
Construction:
Total loans, net of unamortized deferred loan fees and discounts	348,789	356,874
Total loans, net of unamortized deferred loan fees and discounts	348,789	356,874
Commercial Portfolio Segment [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	216,015	220,412
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	216,015	220,412
Construction:
Total loans, net of unamortized deferred loan fees and discounts	216,015	220,412
Total loans, net of unamortized deferred loan fees and discounts	216,015	220,412
Construction [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	145,550	137,557
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	145,550	137,557
Construction:
Total loans, net of unamortized deferred loan fees and discounts	145,550	137,557
Total loans, net of unamortized deferred loan fees and discounts	145,550	137,557
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	386,111	385,426
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	386,111	385,426
Construction:
Total loans, net of unamortized deferred loan fees and discounts	386,111	385,426
Total loans, net of unamortized deferred loan fees and discounts	386,111	385,426
Home Equity Loans [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	41,932	43,031	40,241
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	41,932	43,031	40,241
Construction:
Total loans, net of unamortized deferred loan fees and discounts	41,932	43,031	40,241
Total loans, net of unamortized deferred loan fees and discounts	41,932	43,031	40,241
Allowance for loan losses	(1,736)	(1,841)	(2,451)	(2,644)
Other Consumer [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	23,606	25,155	29,313
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	23,606	25,155	29,313
Construction:
Total loans, net of unamortized deferred loan fees and discounts	23,606	25,155	29,313
Total loans, net of unamortized deferred loan fees and discounts	23,606	25,155	29,313
Allowance for loan losses	(570)	(586)	(595)	(622)
Commercial [Member] | Mortgage Loans on Real Estate [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	1,973,268	1,914,896	1,761,114
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	1,973,268	1,914,896	1,761,114
Construction:
Total loans, net of unamortized deferred loan fees and discounts	1,973,268	1,914,896	1,761,114
Total loans, net of unamortized deferred loan fees and discounts	1,973,268	1,914,896	1,761,114
Allowance for loan losses	(11,495)	(11,441)	(11,542)	(11,517)
Commercial [Member] | Construction [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	73,952	69,627	64,843
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	73,952	69,627	64,843
Construction:
Total loans, net of unamortized deferred loan fees and discounts	73,952	69,627	64,843
Total loans, net of unamortized deferred loan fees and discounts	73,952	69,627	64,843
Allowance for loan losses	(847)	(642)	(572)	(680)
Home Equity Lines of Credit [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	283,251	288,688	283,596
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	283,251	288,688	283,596
Construction:
Total loans, net of unamortized deferred loan fees and discounts	283,251	288,688	283,596
Total loans, net of unamortized deferred loan fees and discounts	283,251	288,688	283,596
Allowance for loan losses	(5,412)	(5,800)	(6,530)	(7,044)
Residential [Member] | Mortgage Loans on Real Estate [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	386,111	385,426	309,701
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	386,111	385,426	309,701
Construction:
Total loans, net of unamortized deferred loan fees and discounts	386,111	385,426	309,701
Total loans, net of unamortized deferred loan fees and discounts	386,111	385,426	309,701
Allowance for loan losses	(2,170)	(2,317)	(2,662)	(2,748)
Residential [Member] | Construction [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	71,598	67,930	59,699
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	71,598	67,930	59,699
Construction:
Total loans, net of unamortized deferred loan fees and discounts	71,598	67,930	59,699
Total loans, net of unamortized deferred loan fees and discounts	71,598	67,930	59,699
Allowance for loan losses	(1,351)	(1,184)	$ (1,339)	$ (1,417)
Originated [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	2,755,148	2,690,402
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	2,755,148	2,690,402
Construction:
Total loans, net of unamortized deferred loan fees and discounts	2,755,148	2,690,402
Commercial	2,764,819	2,699,053
Unamortized net deferred loan fees	(9,671)	(8,651)
Total loans, net of unamortized deferred loan fees and discounts	2,755,148	2,690,402
Allowance for loan losses	(29,057)	(29,122)
Originated [Member] | Mortgage Loans on Real Estate [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	2,077,223	2,011,032
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	2,077,223	2,011,032
Construction:
Total loans, net of unamortized deferred loan fees and discounts	2,077,223	2,011,032
Total loans, net of unamortized deferred loan fees and discounts	2,077,223	2,011,032
Originated [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	326,962	332,649
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	326,962	332,649
Construction:
Total loans, net of unamortized deferred loan fees and discounts	326,962	332,649
Total loans, net of unamortized deferred loan fees and discounts	326,962	332,649
Originated [Member] | Commercial Portfolio Segment [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	205,673	209,437
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	205,673	209,437
Construction:
Total loans, net of unamortized deferred loan fees and discounts	205,673	209,437
Total loans, net of unamortized deferred loan fees and discounts	205,673	209,437
Originated [Member] | Construction [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	145,290	137,284
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	145,290	137,284
Construction:
Total loans, net of unamortized deferred loan fees and discounts	145,290	137,284
Total loans, net of unamortized deferred loan fees and discounts	145,290	137,284
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	323,161	320,522
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	323,161	320,522
Construction:
Total loans, net of unamortized deferred loan fees and discounts	323,161	320,522
Total loans, net of unamortized deferred loan fees and discounts	323,161	320,522
Originated [Member] | Home Equity Loans [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	38,889	39,848
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	38,889	39,848
Construction:
Total loans, net of unamortized deferred loan fees and discounts	38,889	39,848
Total loans, net of unamortized deferred loan fees and discounts	38,889	39,848
Originated [Member] | Other Consumer [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	21,422	22,859
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	21,422	22,859
Construction:
Total loans, net of unamortized deferred loan fees and discounts	21,422	22,859
Total loans, net of unamortized deferred loan fees and discounts	21,422	22,859
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	1,754,062	1,690,510
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	1,754,062	1,690,510
Construction:
Total loans, net of unamortized deferred loan fees and discounts	1,754,062	1,690,510
Total loans, net of unamortized deferred loan fees and discounts	1,754,062	1,690,510
Originated [Member] | Commercial [Member] | Construction [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	73,701	69,364
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	73,701	69,364
Construction:
Total loans, net of unamortized deferred loan fees and discounts	73,701	69,364
Total loans, net of unamortized deferred loan fees and discounts	73,701	69,364
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	266,651	269,942
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	266,651	269,942
Construction:
Total loans, net of unamortized deferred loan fees and discounts	266,651	269,942
Total loans, net of unamortized deferred loan fees and discounts	266,651	269,942
Originated [Member] | Residential [Member] | Construction [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	71,589	67,920
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	71,589	67,920
Construction:
Total loans, net of unamortized deferred loan fees and discounts	71,589	67,920
Total loans, net of unamortized deferred loan fees and discounts	71,589	67,920
PNCI [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	300,109	309,203
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	300,109	309,203
Construction:
Total loans, net of unamortized deferred loan fees and discounts	300,109	309,203
Commercial	306,924	316,238
Discounts to principal balance of loans owed, net of charge-offs	(6,815)	(7,035)
Total loans, net of unamortized deferred loan fees and discounts	300,109	309,203
Allowance for loan losses	(748)	(929)
PNCI [Member] | Mortgage Loans on Real Estate [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	272,374	279,342
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	272,374	279,342
Construction:
Total loans, net of unamortized deferred loan fees and discounts	272,374	279,342
Total loans, net of unamortized deferred loan fees and discounts	272,374	279,342
PNCI [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	19,638	21,197
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	19,638	21,197
Construction:
Total loans, net of unamortized deferred loan fees and discounts	19,638	21,197
Total loans, net of unamortized deferred loan fees and discounts	19,638	21,197
PNCI [Member] | Commercial Portfolio Segment [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	7,837	8,391
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	7,837	8,391
Construction:
Total loans, net of unamortized deferred loan fees and discounts	7,837	8,391
Total loans, net of unamortized deferred loan fees and discounts	7,837	8,391
PNCI [Member] | Construction [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	260	273
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	260	273
Construction:
Total loans, net of unamortized deferred loan fees and discounts	260	273
Total loans, net of unamortized deferred loan fees and discounts	260	273
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	61,206	63,519
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	61,206	63,519
Construction:
Total loans, net of unamortized deferred loan fees and discounts	61,206	63,519
Total loans, net of unamortized deferred loan fees and discounts	61,206	63,519
PNCI [Member] | Home Equity Loans [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	2,558	2,698
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	2,558	2,698
Construction:
Total loans, net of unamortized deferred loan fees and discounts	2,558	2,698
Total loans, net of unamortized deferred loan fees and discounts	2,558	2,698
PNCI [Member] | Other Consumer [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	2,141	2,251
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	2,141	2,251
Construction:
Total loans, net of unamortized deferred loan fees and discounts	2,141	2,251
Total loans, net of unamortized deferred loan fees and discounts	2,141	2,251
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	211,168	215,823
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	211,168	215,823
Construction:
Total loans, net of unamortized deferred loan fees and discounts	211,168	215,823
Total loans, net of unamortized deferred loan fees and discounts	211,168	215,823
PNCI [Member] | Commercial [Member] | Construction [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	251	263
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	251	263
Construction:
Total loans, net of unamortized deferred loan fees and discounts	251	263
Total loans, net of unamortized deferred loan fees and discounts	251	263
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	14,939	16,248
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	14,939	16,248
Construction:
Total loans, net of unamortized deferred loan fees and discounts	14,939	16,248
Total loans, net of unamortized deferred loan fees and discounts	14,939	16,248
PNCI [Member] | Residential [Member] | Construction [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	9	10
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	9	10
Construction:
Total loans, net of unamortized deferred loan fees and discounts	9	10
Total loans, net of unamortized deferred loan fees and discounts	9	10
PCI - Cash Basis [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	1,619	2,069
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	1,619	2,069
Construction:
Total loans, net of unamortized deferred loan fees and discounts	1,619	2,069
Commercial	5,167	5,863
Discounts to principal balance of loans owed, net of charge-offs	(3,548)	(3,794)
Total loans, net of unamortized deferred loan fees and discounts	1,619	2,069
Allowance for loan losses	(8)	(17)
PCI - Cash Basis [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	1,619	2,069
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	1,619	2,069
Construction:
Total loans, net of unamortized deferred loan fees and discounts	1,619	2,069
Total loans, net of unamortized deferred loan fees and discounts	1,619	2,069
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	1,619	2,069
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	1,619	2,069
Construction:
Total loans, net of unamortized deferred loan fees and discounts	1,619	2,069
Total loans, net of unamortized deferred loan fees and discounts	1,619	2,069
PCI - Other [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	12,857	13,491
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	12,857	13,491
Construction:
Total loans, net of unamortized deferred loan fees and discounts	12,857	13,491
Commercial	16,654	17,318
Discounts to principal balance of loans owed, net of charge-offs	(3,797)	(3,827)
Total loans, net of unamortized deferred loan fees and discounts	12,857	13,491
Allowance for loan losses	(160)	(255)
PCI - Other [Member] | Mortgage Loans on Real Estate [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	9,782	9,948
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	9,782	9,948
Construction:
Total loans, net of unamortized deferred loan fees and discounts	9,782	9,948
Total loans, net of unamortized deferred loan fees and discounts	9,782	9,948
PCI - Other [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	570	959
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	570	959
Construction:
Total loans, net of unamortized deferred loan fees and discounts	570	959
Total loans, net of unamortized deferred loan fees and discounts	570	959
PCI - Other [Member] | Commercial Portfolio Segment [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	2,505	2,584
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	2,505	2,584
Construction:
Total loans, net of unamortized deferred loan fees and discounts	2,505	2,584
Total loans, net of unamortized deferred loan fees and discounts	2,505	2,584
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	1,744	1,385
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	1,744	1,385
Construction:
Total loans, net of unamortized deferred loan fees and discounts	1,744	1,385
Total loans, net of unamortized deferred loan fees and discounts	1,744	1,385
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	485
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	485	485
Construction:
Total loans, net of unamortized deferred loan fees and discounts	485	485
Total loans, net of unamortized deferred loan fees and discounts	485	485
PCI - Other [Member] | Other Consumer [Member] | Consumer [Member]
Mortgage loans on real estate:
Total loans, net of unamortized deferred loan fees and discounts	43	45
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	43	45
Construction:
Total loans, net of unamortized deferred loan fees and discounts	43	45
Total loans, net of unamortized deferred loan fees and discounts	43	45
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	8,038	8,563
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	8,038	8,563
Construction:
Total loans, net of unamortized deferred loan fees and discounts	8,038	8,563
Total loans, net of unamortized deferred loan fees and discounts	8,038	8,563
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	42	429
Consumer:
Total loans, net of unamortized deferred loan fees and discounts	42	429
Construction:
Total loans, net of unamortized deferred loan fees and discounts	42	429
Total loans, net of unamortized deferred loan fees and discounts	$ 42	$ 429

Loans - Change in Accretable Yi

Loans - Change in Accretable Yield for PCI (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Change in accretable yield:
Balance at beginning of period	$ 4,262	$ 10,348
Accretion to interest income	(255)	(902)
Reclassification (to) from nonaccretable difference	140	114
Balance at end of period	$ 4,147	$ 9,560

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	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	$ 3,069,733	$ 2,761,192	$ 3,015,165
Individ. evaluated for impairment	25,803	27,650	28,234
Loans pooled for evaluation	3,029,454	2,710,005	2,971,371
Beginning balance	30,323	32,503	32,503
Charge-offs	(480)	(409)	(4,410)
Recoveries	366	480	2,141
(Benefit) provision	(236)	(1,557)	89
Ending balance	29,973	31,017	30,323
Ending balance:
Individ. evaluated for impairment	3,091	1,686	2,699
Loans pooled for evaluation	26,714	26,900	27,352
Mortgage Loans on Real Estate [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	2,359,379		2,300,322
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	386,111	309,701	385,426
Individ. evaluated for impairment	5,535	3,849	5,298
Loans pooled for evaluation	378,832	304,493	378,743
Beginning balance	2,317	2,748	2,748
Charge-offs	(1)		(60)
(Benefit) provision	(146)	(86)	(371)
Ending balance	2,170	2,662	2,317
Ending balance:
Individ. evaluated for impairment	190	249	230
Loans pooled for evaluation	1,910	2,188	1,932
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	1,973,268	1,761,114	1,914,896
Individ. evaluated for impairment	11,110	16,979	13,911
Loans pooled for evaluation	1,954,120	1,731,785	1,892,422
Beginning balance	11,441	11,517	11,517
Charge-offs			(186)
Recoveries	15	110	397
(Benefit) provision	39	(85)	(287)
Ending balance	11,495	11,542	11,441
Ending balance:
Individ. evaluated for impairment	154	124	30
Loans pooled for evaluation	11,281	9,971	11,351
Consumer [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	348,789		356,874
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	283,251	283,596	288,688
Individ. evaluated for impairment	2,450	2,204	2,688
Loans pooled for evaluation	279,140	277,388	283,502
Beginning balance	5,800	7,044	7,044
Charge-offs	(80)	(71)	(98)
Recoveries	209	46	698
(Benefit) provision	(517)	(489)	(1,844)
Ending balance	5,412	6,530	5,800
Ending balance:
Individ. evaluated for impairment	448	400	427
Loans pooled for evaluation	4,956	6,122	5,356
Consumer and Industrial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	216,015	212,685	220,412
Individ. evaluated for impairment	4,621	3,072	4,470
Loans pooled for evaluation	208,889	205,832	213,358
Beginning balance	6,512	5,831	5,831
Charge-offs	(205)	(133)	(1,444)
Recoveries	50	170	428
(Benefit) provision	35	(542)	1,697
Ending balance	6,392	5,326	6,512
Ending balance:
Individ. evaluated for impairment	2,113	811	1,848
Loans pooled for evaluation	4,249	3,873	4,624
Construction [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	145,550		137,557
Construction [Member] | Residential [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	71,598	59,699	67,930
Individ. evaluated for impairment	136	25	140
Loans pooled for evaluation	71,462	58,830	67,790
Beginning balance	1,184	1,417	1,417
Charge-offs			(1,104)
(Benefit) provision	167	(78)	871
Ending balance	1,351	1,339	1,184
Ending balance:
Individ. evaluated for impairment		14
Loans pooled for evaluation	1,351	1,282	1,184
Construction [Member] | Commercial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	73,952	64,843	69,627
Loans pooled for evaluation	73,952	64,843	69,627
Beginning balance	642	680	680
Recoveries		1	1
(Benefit) provision	205	(109)	(39)
Ending balance	847	572	642
Ending balance:
Loans pooled for evaluation	847	572	642
Home Equity Loans [Member] | Consumer [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	41,932	40,241	43,031
Individ. evaluated for impairment	1,673	1,241	1,470
Loans pooled for evaluation	39,774	37,867	41,076
Beginning balance	1,841	2,644	2,644
Charge-offs		(31)	(332)
Recoveries	14	12	242
(Benefit) provision	(119)	(174)	(713)
Ending balance	1,736	2,451	1,841
Ending balance:
Individ. evaluated for impairment	130	57	107
Loans pooled for evaluation	1,606	2,328	1,734
Other Consumer [Member] | Consumer [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	23,606	29,313	25,155
Individ. evaluated for impairment	278	280	257
Loans pooled for evaluation	23,285	28,967	24,853
Beginning balance	586	622	622
Charge-offs	(194)	(174)	(1,186)
Recoveries	78	141	375
(Benefit) provision	100	6	775
Ending balance	570	595	586
Ending balance:
Individ. evaluated for impairment	56	31	57
Loans pooled for evaluation	514	564	529
Receivables Acquired with Deteriorated Credit Quality [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	14,476	23,537	15,560
Ending balance:
Loans acquired with deteriorated credit quality	168	2,431	272
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	1,744	1,359	1,385
Ending balance:
Loans acquired with deteriorated credit quality	70	225	155
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	8,038	12,350	8,563
Ending balance:
Loans acquired with deteriorated credit quality	60	1,447	60
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	1,661	4,004	2,498
Ending balance:
Loans acquired with deteriorated credit quality	8	8	17
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	2,505	3,781	2,584
Ending balance:
Loans acquired with deteriorated credit quality	30	642	40
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		844
Ending balance:
Loans acquired with deteriorated credit quality		43
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	1,133	485
Ending balance:
Loans acquired with deteriorated credit quality		66
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	$ 43	$ 66	$ 45

Allowance for Loan Losses - Pre

Allowance for Loan Losses - Presentation of Credit Quality Indicators (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	$ 3,069,733	$ 3,015,165	$ 2,761,192
Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	2,755,148	2,690,402
PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	300,109	309,203
PCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	14,476	15,560
Pass [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	2,688,622	2,617,171
Pass [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	286,976	293,331
Special Mention [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	41,469	38,662
Special Mention [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	9,694	12,408
Substandard [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	25,057	34,569
Substandard [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	3,439	3,464
Mortgage Loans on Real Estate [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	2,359,379	2,300,322
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	386,111	385,426	309,701
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	323,161	320,522
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	61,206	63,519
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	1,744	1,385
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	317,799	315,120
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	59,184	61,411
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	2,274	2,234
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	214	218
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	3,088	3,168
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	1,808	1,890
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	1,973,268	1,914,896	1,761,114
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	1,754,062	1,690,510
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	211,168	215,823
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	8,038	8,563
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	1,716,599	1,649,333
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	201,641	203,751
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	23,679	18,434
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	8,977	11,513
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	13,784	22,743
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	550	559
Consumer [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	348,789	356,874
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	283,251	288,688	283,596
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	266,651	269,942
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	14,939	16,248
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	1,661	2,498
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	263,270	265,345
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	13,686	14,866
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	1,628	2,558
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	282	450
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	1,753	2,039
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	971	932
Consumer [Member] | Home Equity Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	41,932	43,031	40,241
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	38,889	39,848
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	2,558	2,698
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	485
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	35,730	37,428
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	2,301	2,433
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	1,532	800
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	184	188
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	1,627	1,620
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	73	77
Consumer [Member] | Other Consumer [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	23,606	25,155	29,313
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	21,422	22,859
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	2,141	2,251
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	43	45
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	21,067	22,432
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	2,067	2,207
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	238	272
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	37	38
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	117	155
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	37	6
Consumer and Industrial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	216,015	220,412	212,685
Consumer and Industrial [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	205,673	209,437
Consumer and Industrial [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	7,837	8,391
Consumer and Industrial [Member] | PCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	2,505	2,584
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	193,829	195,208
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	7,837	8,390
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	7,263	9,492
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
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	4,581	4,737
Construction [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	145,550	137,557
Construction [Member] | Residential [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	71,598	67,930	59,699
Construction [Member] | Residential [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	71,589	67,920
Construction [Member] | Residential [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	9	10
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	71,482	67,813
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	9	10
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	107
Construction [Member] | Commercial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	73,952	69,627	$ 64,843
Construction [Member] | Commercial [Member] | Originated Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	73,701	69,364
Construction [Member] | Commercial [Member] | PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total loans, net of unamortized deferred loan fees and discounts	251	263
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	68,846	64,492
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	251	263
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	$ 4,855	$ 4,872

Allowance for Loan Losses - Add

Allowance for Loan Losses - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2018USD ($)Category	Dec. 31, 2017USD ($)	Mar. 31, 2017USD ($)
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	$ 9,781,000	$ 12,517,000	$ 12,285,000
Additional funds in TDR	1,000	1,000	70,000
PNCI Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Impaired TDR Loans	1,471,000	1,352,000	1,470,000
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	Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total originated loans	$ 3,069,733	$ 3,015,165
Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	17,336	8,927
Current	2,737,812	2,681,475
Total originated loans	2,755,148	2,690,402
Nonaccrual loans	16,080	15,462
PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	3,080	2,682
Current	297,029	306,521
Total originated loans	300,109	309,203
> 90 Days and still accruing		281
Nonaccrual loans	1,711	1,463
30-59 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	11,452	3,983
30-59 Days [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	2,902	1,899
60-89 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	1,845	2,426
60-89 Days [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	4	344
> 90 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	4,039	2,518
> 90 Days [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	174	439
Mortgage Loans on Real Estate [Member] | Residential [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	3,063	2,493
Current	320,098	318,029
Total originated loans	323,161	320,522
Nonaccrual loans	2,235	1,725
Mortgage Loans on Real Estate [Member] | Residential [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	2,537	1,694
Current	58,669	61,825
Total originated loans	61,206	63,519
> 90 Days and still accruing		81
Nonaccrual loans	1,067	1,012
Mortgage Loans on Real Estate [Member] | Commercial [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	6,693	1,145
Current	1,747,369	1,689,365
Total originated loans	1,754,062	1,690,510
Nonaccrual loans	7,925	8,144
Mortgage Loans on Real Estate [Member] | Commercial [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		70
Current	211,168	215,753
Total originated loans	211,168	215,823
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	2,217	1,740
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	2,537	1,495
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	5,531	158
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
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
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
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	846	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
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	1,162
Consumer [Member] | Home Equity Lines of Credit [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	1,284	948
Current	265,367	268,994
Total originated loans	266,651	269,942
Nonaccrual loans	733	811
Consumer [Member] | Home Equity Lines of Credit [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	508	856
Current	14,431	15,392
Total originated loans	14,939	16,248
> 90 Days and still accruing		200
Nonaccrual loans	571	402
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	938	528
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	362	298
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	26	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	320	372
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	146	330
Consumer [Member] | Home Equity Loans [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	1,662	991
Current	37,227	38,857
Total originated loans	38,889	39,848
Nonaccrual loans	1,193	1,106
Consumer [Member] | Home Equity Loans [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	2	30
Current	2,556	2,668
Total originated loans	2,558	2,698
Nonaccrual loans	40	44
Consumer [Member] | Home Equity Loans [Member] | 30-59 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	1,490	511
Consumer [Member] | Home Equity Loans [Member] | 30-59 Days [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	2	30
Consumer [Member] | Home Equity Loans [Member] | 60-89 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	18	107
Consumer [Member] | Home Equity Loans [Member] | > 90 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	154	373
Consumer [Member] | Other Consumer [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	81	95
Current	21,341	22,764
Total originated loans	21,422	22,859
Nonaccrual loans	4	7
Consumer [Member] | Other Consumer [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	32	32
Current	2,109	2,219
Total originated loans	2,141	2,251
Nonaccrual loans	33	5
Consumer [Member] | Other Consumer [Member] | 30-59 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	63	56
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	18	36
Consumer [Member] | Other Consumer [Member] | 60-89 Days [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	4	26
Consumer [Member] | Other Consumer [Member] | > 90 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due		3
Consumer [Member] | Other Consumer [Member] | > 90 Days [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	28
Consumer and Industrial [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	3,006	3,221
Current	202,667	206,216
Total originated loans	205,673	209,437
Nonaccrual loans	3,990	3,669
Consumer and Industrial [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	1
Current	7,836	8,391
Total originated loans	7,837	8,391
Consumer and Industrial [Member] | 30-59 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	915	956
Consumer and Industrial [Member] | 30-59 Days [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	1
Consumer and Industrial [Member] | 60-89 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	534	738
Consumer and Industrial [Member] | > 90 Days [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	1,557	1,527
Construction [Member] | Residential [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	298	34
Current	71,291	67,886
Total originated loans	71,589	67,920
Construction [Member] | Residential [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	9	10
Total originated loans	9	10
Construction [Member] | Commercial [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	1,249
Current	72,452	69,364
Total originated loans	73,701	69,364
Construction [Member] | Commercial [Member] | PNCI Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	251	263
Total originated loans	251	263
Construction [Member] | 30-59 Days [Member] | Residential [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	298	$ 34
Construction [Member] | 60-89 Days [Member] | Commercial [Member] | Originated Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total past due	$ 1,249

Allowance for Loan Losses - Imp

Allowance for Loan Losses - Impaired Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Originated Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	$ 15,624	$ 19,325	$ 18,078
Unpaid principal, With no related allowance recorded	16,477	20,237	18,850
Average recorded investment, With no related allowance recorded	16,851	27,413	17,891
Interest income recognized, With no related allowance recorded	71	132	774
Recorded investment, With an allowance recorded	7,254	4,703	7,188
Unpaid principal, With an allowance recorded	7,426	4,783	7,328
Related allowance, With an allowance recorded	2,617	1,192	2,232
Average recorded investment, With an allowance recorded	7,221	6,310	6,735
Interest income recognized, With an allowance recorded	41	40	278
PNCI Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	1,901	2,626	1,994
Unpaid principal, With no related allowance recorded	2,001	2,905	2,073
Average recorded investment, With no related allowance recorded	1,947	2,842	2,545
Interest income recognized, With no related allowance recorded	4	5	46
Recorded investment, With an allowance recorded	1,024	996	974
Unpaid principal, With an allowance recorded	1,026	996	975
Related allowance, With an allowance recorded	474	494	467
Average recorded investment, With an allowance recorded	999	2,312	1,018
Interest income recognized, With an allowance recorded	8	10	43
Mortgage Loans on Real Estate [Member] | Residential [Member] | Originated Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	2,678	1,782	2,058
Unpaid principal, With no related allowance recorded	2,829	1,793	2,109
Average recorded investment, With no related allowance recorded	2,368	2,834	1,875
Interest income recognized, With no related allowance recorded	19	20	85
Recorded investment, With an allowance recorded	1,525	1,378	1,881
Unpaid principal, With an allowance recorded	1,549	1,382	1,914
Related allowance, With an allowance recorded	190	172	230
Average recorded investment, With an allowance recorded	1,703	1,692	1,626
Interest income recognized, With an allowance recorded	9	11	58
Mortgage Loans on Real Estate [Member] | Residential [Member] | PNCI Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	1,332	433	1,359
Unpaid principal, With no related allowance recorded	1,390	455	1,404
Average recorded investment, With no related allowance recorded	1,345	654	911
Interest income recognized, With no related allowance recorded	2	2	24
Recorded investment, With an allowance recorded		256
Unpaid principal, With an allowance recorded		256
Related allowance, With an allowance recorded		77
Average recorded investment, With an allowance recorded		128	130
Interest income recognized, With an allowance recorded		2
Mortgage Loans on Real Estate [Member] | Commercial [Member] | Originated Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	9,848	14,431	13,101
Unpaid principal, With no related allowance recorded	10,126	14,881	13,360
Average recorded investment, With no related allowance recorded	11,474	20,770	13,123
Interest income recognized, With no related allowance recorded	35	98	609
Recorded investment, With an allowance recorded	1,262	640	810
Unpaid principal, With an allowance recorded	1,281	640	826
Related allowance, With an allowance recorded	154	18	30
Average recorded investment, With an allowance recorded	1,036	1,029	728
Interest income recognized, With an allowance recorded	9	9	36
Mortgage Loans on Real Estate [Member] | Commercial [Member] | PNCI Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded		1,777
Unpaid principal, With no related allowance recorded		2,011
Average recorded investment, With no related allowance recorded		1,455	913
Recorded investment, With an allowance recorded		131
Unpaid principal, With an allowance recorded		131
Related allowance, With an allowance recorded		106
Average recorded investment, With an allowance recorded		1,440	66
Interest income recognized, With an allowance recorded		2
Consumer [Member] | Home Equity Lines of Credit [Member] | Originated Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	888	1,064	1,093
Unpaid principal, With no related allowance recorded	944	1,144	1,175
Average recorded investment, With no related allowance recorded	991	2,013	1,287
Interest income recognized, With no related allowance recorded	6	6	39
Recorded investment, With an allowance recorded	527	427	401
Unpaid principal, With an allowance recorded	534	440	406
Related allowance, With an allowance recorded	146	106	111
Average recorded investment, With an allowance recorded	464	1,076	415
Interest income recognized, With an allowance recorded	4	1	8
Consumer [Member] | Home Equity Lines of Credit [Member] | PNCI Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	501	220	591
Unpaid principal, With no related allowance recorded	529	233	612
Average recorded investment, With no related allowance recorded	546	337	663
Interest income recognized, With no related allowance recorded	2	1	22
Recorded investment, With an allowance recorded	534	493	603
Unpaid principal, With an allowance recorded	536	493	604
Related allowance, With an allowance recorded	302	295	316
Average recorded investment, With an allowance recorded	568	550	577
Interest income recognized, With an allowance recorded	3	5	26
Consumer [Member] | Home Equity Loans [Member] | Originated Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	1,193	743	1,107
Unpaid principal, With no related allowance recorded	1,548	1,085	1,429
Average recorded investment, With no related allowance recorded	1,150	845	852
Interest income recognized, With no related allowance recorded		1	14
Recorded investment, With an allowance recorded	196	440	198
Unpaid principal, With an allowance recorded	196	443	198
Related allowance, With an allowance recorded	10	57	10
Average recorded investment, With an allowance recorded	197	557	341
Interest income recognized, With an allowance recorded	2	5	10
Consumer [Member] | Home Equity Loans [Member] | PNCI Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	40	58	44
Unpaid principal, With no related allowance recorded	54	67	57
Average recorded investment, With no related allowance recorded	42	64	56
Recorded investment, With an allowance recorded	244		121
Unpaid principal, With an allowance recorded	244		121
Related allowance, With an allowance recorded	120		97
Average recorded investment, With an allowance recorded	183	19	61
Interest income recognized, With an allowance recorded	3		6
Consumer [Member] | Other Consumer [Member] | Originated Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded		5	4
Unpaid principal, With no related allowance recorded		6	52
Average recorded investment, With no related allowance recorded	2	12	10
Recorded investment, With an allowance recorded	4	21	3
Unpaid principal, With an allowance recorded	4	22	3
Related allowance, With an allowance recorded	4	14	3
Average recorded investment, With an allowance recorded	4	11	10
Consumer [Member] | Other Consumer [Member] | PNCI Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	28	138
Unpaid principal, With no related allowance recorded	28	139
Average recorded investment, With no related allowance recorded	14	86	2
Interest income recognized, With no related allowance recorded		2
Recorded investment, With an allowance recorded	246	116	250
Unpaid principal, With an allowance recorded	246	116	250
Related allowance, With an allowance recorded	52	16	54
Average recorded investment, With an allowance recorded	248	175	184
Interest income recognized, With an allowance recorded	2	1	11
Consumer and Industrial [Member] | Originated Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment, With no related allowance recorded	881	1,289	575
Unpaid principal, With no related allowance recorded	894	1,312	585
Average recorded investment, With no related allowance recorded	728	932	668
Interest income recognized, With no related allowance recorded	9	7	18
Recorded investment, With an allowance recorded	3,740	1,783	3,895
Unpaid principal, With an allowance recorded	3,862	1,842	3,981
Related allowance, With an allowance recorded	2,113	811	1,848
Average recorded investment, With an allowance recorded	3,817	1,938	3,615
Interest income recognized, With an allowance recorded	17	14	166
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	136	11	140
Unpaid principal, With no related allowance recorded	136	16	140
Average recorded investment, With no related allowance recorded	138	7	76
Interest income recognized, With no related allowance recorded	$ 2		$ 9
Recorded investment, With an allowance recorded		14
Unpaid principal, With an allowance recorded		14
Related allowance, With an allowance recorded		14
Average recorded investment, With an allowance recorded		7
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	3 Months Ended	12 Months Ended
	Mar. 31, 2018USD ($)SecurityLoan	Dec. 31, 2017USD ($)SecurityLoan
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan	3	26
Pre-mod outstanding principal balance	$ 638	$ 7,111
Post-mod outstanding principal balance	643	6,978
Financial impact due to TDR taken as additional provision	$ 11	$ 133
Number that defaulted during the period | SecurityLoan	1	5
Recorded investment of TDRs that defaulted during the period	$ 169	$ 624
Financial impact due to the default of previous TDR taken as charge-offs or additional provisions		$ (5)
Mortgage Loans on Real Estate [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan		1
Pre-mod outstanding principal balance		$ 939
Post-mod outstanding principal balance		939
Financial impact due to TDR taken as additional provision		$ 169
Number that defaulted during the period | SecurityLoan		2
Recorded investment of TDRs that defaulted during the period		$ 223
Mortgage Loans on Real Estate [Member] | Commercial [Member]
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan	1	8
Pre-mod outstanding principal balance	$ 384	$ 3,721
Post-mod outstanding principal balance	384	3,695
Financial impact due to TDR taken as additional provision	$ 11	$ (111)
Number that defaulted during the period | SecurityLoan	1	1
Recorded investment of TDRs that defaulted during the period	$ 169	$ 219
Consumer [Member] | Home Equity Lines of Credit [Member]
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan	1	3
Pre-mod outstanding principal balance	$ 133	$ 187
Post-mod outstanding principal balance	$ 138	187
Financial impact due to TDR taken as additional provision		$ 27
Number that defaulted during the period | SecurityLoan		1
Recorded investment of TDRs that defaulted during the period		$ 127
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
Pre-mod outstanding principal balance	$ 121	$ 252
Post-mod outstanding principal balance	$ 121	$ 252
Number that defaulted during the period | SecurityLoan		1
Recorded investment of TDRs that defaulted during the period		$ 55
Consumer [Member] | Other Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan		1
Pre-mod outstanding principal balance		$ 14
Post-mod outstanding principal balance		14
Financial impact due to TDR taken as additional provision		$ 11
Consumer and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan		11
Pre-mod outstanding principal balance		$ 1,854
Post-mod outstanding principal balance		1,747
Financial impact due to TDR taken as additional provision		$ 37
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	3 Months Ended
	Mar. 31, 2018USD ($)Assets	Mar. 31, 2017USD ($)Assets
Schedule Of Foreclosed Assets Activity [Line Items]
Beginning balance, net	$ 3,226	$ 3,986
Additions/transfers from loans		85
Dispositions/sales	(1,572)	(608)
Valuation adjustments	(90)	66
Ending balance, net	1,564	3,529
Ending valuation allowance	$ (152)	$ (300)
Ending number of foreclosed assets | Assets	10	12
Proceeds from sale of foreclosed assets	$ 1,943	$ 726
Gain (loss) on sale of foreclosed assets	$ 371	118
Noncovered [Member]
Schedule Of Foreclosed Assets Activity [Line Items]
Beginning balance, net		3,763
Additions/transfers from loans		85
Dispositions/sales		(385)
Valuation adjustments		66
Ending balance, net		3,529
Ending valuation allowance		$ (300)
Ending number of foreclosed assets | Assets		12
Proceeds from sale of foreclosed assets		$ 510
Gain (loss) on sale of foreclosed assets		125
Covered [Member]
Schedule Of Foreclosed Assets Activity [Line Items]
Beginning balance, net		223
Dispositions/sales		(223)
Proceeds from sale of foreclosed assets		216
Gain (loss) on sale of foreclosed assets		$ (7)

Foreclosed Assets - Additional

Foreclosed Assets - Additional Information (Detail) - USD ($)	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Schedule Of Foreclosed Assets Activity [Line Items]
Foreclosed assets	$ 1,564,000	$ 3,226,000	$ 3,529,000	$ 3,986,000
Residential Real Estate [Member]
Schedule Of Foreclosed Assets Activity [Line Items]
Foreclosed assets	836,000
Formal foreclosure proceedings	$ 407,000

Premises and Equipment - Summar

Premises and Equipment - Summary of Premises and Equipment (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment, Net, by Type [Abstract]
Land & land improvements	$ 9,959	$ 9,959
Buildings	50,792	50,340
Furniture and equipment	37,348	35,939
Premises and equipment, gross	98,099	96,238
Less: Accumulated depreciation	(41,678)	(40,644)
Premises and equipment less depreciation, gross	56,421	55,594
Construction in progress	2,137	2,148
Total premises and equipment	$ 58,558	$ 57,742

Premises and Equipment - Additi

Premises and Equipment - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Property, Plant and Equipment [Abstract]
Depreciation expense for premises and equipment	$ 1,371,000	$ 1,311,000

Cash Value of Life Insurance -

Cash Value of Life Insurance - Summary of Activity in Balance of Cash Value of Life Insurance (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)PoliciesEmployeesCompany	Mar. 31, 2017USD ($)PoliciesEmployeesCompany
Increase (Decrease) in Insurance Liabilities [Abstract]
Beginning balance	$ 97,783	$ 95,912
Increase in cash value of life insurance	608	685
Gain on death benefit		107
Insurance proceeds receivable reclassified to other assets		(921)
Ending balance	98,391	95,783
End of period death benefit	$ 159,640	$ 164,574
Number of policies owned | Policies	182	183
Insurance companies used | Company	14	14
Current and former employees and directors covered | Employees	57	58

Cash Value of Life Insurance 86

Cash Value of Life Insurance - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2018PoliciesCompany	Mar. 31, 2017Company
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 Intangible87

Goodwill and Other Intangible Assets - Summary of Goodwill Intangible (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
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 Intangible88

Goodwill and Other Intangible Assets - Summary of Core Deposit Intangibles (Detail) - Core Deposit Intangibles [Member] $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Finite-Lived Intangible Assets [Line Items]
Core deposit intangibles, Beginning balance	$ 9,558
Core deposit intangibles, Reductions/Amortization	0
Core deposit intangibles, Additions	0
Core deposit intangibles, Ending balance	9,558
Accumulated amortization, Beginning balance	(4,384)
Accumulated amortization, Reductions/Amortization	(339)
Accumulated amortization, Additions	0
Accumulated amortization, Ending balance	(4,723)
Core deposit intangibles, net, Beginning balance	5,174
Core deposit intangibles, net, Reductions/Amortization	(339)
Core deposit intangibles, net, Additions	0
Core deposit intangibles, net, Ending balance	$ 4,835

Goodwill and Other Intangible89

Goodwill and Other Intangible Assets - Additional Information (Detail)	Mar. 18, 2016USD ($)Branches	Oct. 03, 2014USD ($)	Sep. 23, 2011USD ($)
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
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 Intangible90

Goodwill and Other Intangible Assets - Remaining Estimated Core Deposit Intangible Amortization (Detail) - Core Deposit Intangibles [Member] $ in Thousands	Mar. 31, 2018USD ($)
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	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Servicing Assets at Fair Value [Line Items]
Contractually specified servicing fees, late fees and ancillary fees earned	$ 517	$ 521
Weighted-average prepayment speed (CPR)	7.50%	8.30%
Weighted-average discount rate	13.00%	14.00%
Mortgage Servicing Rights [Member]
Servicing Assets at Fair Value [Line Items]
Balance at beginning of period	$ 6,687	$ 6,595	$ 6,595
Additions	155	278
Change in fair value	111	(13)
Balance at end of period	6,953	6,860	6,687
Loans [Member]
Servicing Assets at Fair Value [Line Items]
Balance at beginning of period	811,065	816,623	816,623
Balance at end of period	$ 806,478	$ 822,506	$ 811,065

Indemnification Asset - Summary

Indemnification Asset - Summary of Activity in Balance of Indemnification Asset (Detail) - USD ($) $ in Thousands	May 09, 2017	Mar. 31, 2017
FDIC Indemnification Asset [Roll Forward]
Beginning balance		$ (744)
Effect of actual and estimated future covered losses and recoveries		(191)
Reimbursable (revenue) expenses incurred		(32)
Payments made to (received from) FDIC	$ (184)	72
Ending balance		(895)
Amount of indemnification liability recorded in other assets		(179)
Amount of indemnification liability recorded in other liabilities		(716)
Ending balance		$ (895)

Indemnification Asset - Additio

Indemnification Asset - Additional Information (Detail) - USD ($) $ in Thousands	May 09, 2017	Mar. 31, 2017
Fdic Indemnification Asset [Abstract]
Payment made to FDIC	$ 184	$ (72)
Gain on termination of loss share agreement	$ 712

Other Assets - Summary of Other

Other Assets - Summary of Other Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Deferred tax asset, net	$ 26,266	$ 21,697
Investment in low income housing tax credit funds	17,095	16,854
Prepaid expense	4,411	4,111
Tax refund receivable	4,754	4,754
Capital trusts	1,709	1,706
Software	883	1,126
Life insurance proceeds receivable		2,242
Miscellaneous other assets	1,156	2,561
Total other assets	$ 56,274	$ 55,051

Deposits - Summary of Balances

Deposits - Summary of Balances of Deposits (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Deposits [Abstract]
Noninterest-bearing demand	$ 1,359,996	$ 1,368,218
Interest-bearing demand	1,022,299	971,459
Savings	1,395,481	1,364,518
Time certificates, over $250,000	76,306	73,596
Other time certificates	230,322	231,340
Total deposits	$ 4,084,404	$ 4,009,131

Deposits - Additional Informati

Deposits - Additional Information (Detail) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Schedule Of Deposits [Line Items]
Overdrawn deposit balances classified as consumer loans	$ 1,085,000	$ 1,366,000
California [Member]
Schedule Of Deposits [Line Items]
Certificate of deposits, included in time certificates $250,000 and over	$ 50,000,000	$ 50,000,000

Reserve for Unfunded Commitme97

Reserve for Unfunded Commitments - Summary of Activity in Reserve for Unfunded Commitments (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Balance at beginning of period	$ 3,164	$ 2,719
Change in reserve for unfunded commitments	700	15
Balance at end of period	$ 3,864	$ 2,734

Other Liabilities - Components

Other Liabilities - Components of Other Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Other Liabilities Disclosure [Abstract]
Pension liability	$ 28,686	$ 28,472
Low income housing tax credit fund commitments	7,677	8,554
Deferred compensation	6,809	6,605
Taxes payable	5,243
Accrued salaries and benefits expense	5,180	6,619
Joint beneficiary agreements	3,429	3,365
Loan escrow and servicing payable	1,464	1,958
Deferred revenue	1,077	1,228
Litigation contingency		1,450
Miscellaneous other liabilities	3,964	5,007
Total other liabilities	$ 63,529	$ 63,258

Other Borrowings - Summary of B

Other Borrowings - Summary of Balances of Other Borrowings (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total other borrowings	$ 65,041	$ 122,166
1.87% Fixed Rate FHLB Collateralized Borrowings [Member]
Debt Instrument [Line Items]
Collateralized borrowings	48,000
1.38% Fixed Rate FHLB Collateralized Borrowings [Member]
Debt Instrument [Line Items]
Collateralized borrowings		104,729
0.05% Fixed Rate Collateralized Borrowings [Member]
Debt Instrument [Line Items]
Collateralized borrowings	$ 17,041	$ 17,437

Other Borrowings - Summary o100

Other Borrowings - Summary of Balances of Other Borrowings (Parenthetical) (Detail)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
1.87% Fixed Rate FHLB Collateralized Borrowings [Member]
Debt Instrument [Line Items]
Collateralized borrowing, fixed rate	1.87%
Collateralized borrowing, maturity date	Apr. 2, 2018
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%	0.05%
Collateralized borrowing, maturity date	Apr. 2, 2018	Jan. 2, 2018

Other Borrowings - Additional I

Other Borrowings - Additional Information (Detail) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Schedule Of Borrowings [Line Items]
Security repurchase agreement	$ 0	$ 0
FHLB collateral line of credit, maximum borrowings capacity	1,597,695,000
FHLB collateral line of credit, outstanding balance	48,000,000
FHLB collateral line of credit, remaining borrowing capacity	1,549,695,000
Loans designated as potential collateral under collateralized line of credit with FHLB	205,777,000
Investment securities designated as potential collateral under collateral line of credit	2,138,150,000
Repurchase investment securities sold and pledged as collateral under securities repurchase agreement	31,667,000
Collateralized line of credit with San Francisco Federal Reserve Bank, maximum borrowings capacity	140,921,000
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	140,921,000
Investment securities designated as potential collateral under collateral line of credit with San Francisco Federal Reserve Bank	15,677
Loans designated as potential collateral under collateral line of credit with San Francisco Federal Reserve Bank	262,663,000
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]
Collateralized borrowings	$ 17,041,000	$ 17,437,000

Junior Subordinated Debt - Addi

Junior Subordinated Debt - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2018USD ($)LocationTrust	Dec. 31, 2017USD ($)	Oct. 03, 2014USD ($)
Class of Stock [Line Items]
Number of subsidiary business trusts | Trust	5
Trust preferred securities amount	$ 62,889,000
Subordinated debenture, recorded fair value	$ 56,905,000	$ 56,858,000
Number of locations organized | Location	2
Change in junior subordinated debt	$ 47,000
Capital Trusts [Member]
Class of Stock [Line Items]
Trust preferred securities amount	62,900,000
North Valley Trust II [Member]
Class of Stock [Line Items]
Trust preferred securities amount	6,186,000
Subordinated debenture, recorded fair value	5,145,000	5,135,000	$ 5,006,000
North Valley Trust III [Member]
Class of Stock [Line Items]
Trust preferred securities amount	5,155,000
Subordinated debenture, recorded fair value	4,050,000	4,041,000	3,918,000
North Valley Trust IV [Member]
Class of Stock [Line Items]
Trust preferred securities amount	10,310,000
Subordinated debenture, recorded fair value	$ 6,472,000	$ 6,444,000	$ 6,063,000
North Valley Bancorp [Member]
Class of Stock [Line Items]
Number of locations acquired | Location	3
Acquisition, completion date	Oct. 3, 2014
Maximum [Member]
Class of Stock [Line Items]
Consecutive payments of interest on debenture defer Period	5 years

Junior Subordinated Debt - Summ

Junior Subordinated Debt - Summary of Terms and Recorded Balance of Subordinated Debenture (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Oct. 03, 2014
Subordinated Borrowing [Line Items]
Subordinated debenture, Face Value	$ 62,889,000
Subordinated debenture, Recorded Book Value	$ 56,905,000	$ 56,858,000
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	4.77%
Subordinated debenture, Recorded Book Value	$ 20,619,000	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	4.29%
Subordinated debenture, Recorded Book Value	$ 20,619,000	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	5.02%
Subordinated debenture, Recorded Book Value	$ 5,145,000	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	4.54%
Subordinated debenture, Recorded Book Value	$ 4,050,000	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	3.45%
Subordinated debenture, Recorded Book Value	$ 6,472,000	$ 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)	3 Months Ended
	Mar. 31, 2018USD ($)site$ / sharesshares	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)shares	Aug. 21, 2007shares
Conversion of Stock [Line Items]
Reserves to satisfy Federal regulatory requirements	$ 91,860,000		$ 82,068,000
Number of sites leased under non-cancelable operating leases | site	41
Rent expense under operating leases	$ 921,000	$ 1,047,000
Rent expense offset by rent income	$ 10,000	$ 13,000
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.
Class B common stock of Visa Inc. | shares	22,956,323		22,955,963	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	$ 119.62
Value of unredeemed Class A equivalent shares	$ 2,641,000

Commitments and Contingencie105

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 Contingencie106

Commitments and Contingencies - Summary of Company's Commitments and Contingent Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
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	236,650	187,097
RE Mortgage [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments to extend credit	73,618	66,267
Standby Letters of Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments to extend credit	11,573	13,075
Commercial [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments to extend credit	253,001	257,220
Consumer Loans [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments to extend credit	437,790	422,958
Deposit Account Overdraft Privilege [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Commitments to extend credit	$ 101,411	$ 98,260

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	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	22,956,323		22,955,963		15,814,662
Repurchased shares outstanding	166,600
Market value of common stock	$ 4,000	$ 604,000
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	$ 4,372,000	$ 4,042,000
Common Stock [Member]
Class of Stock [Line Items]
Common stock, shares outstanding	22,956,323	22,873,305	22,955,963	22,867,802
Company's common stock in lieu of cash to exercise options to purchase shares	134	16,251
Market value of common stock	$ 4,000	$ 604,000

Stock Options and Other Equi108

Stock Options and Other Equity-Based Incentive Instruments - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding options under the plan	446,400	446,400
Options currently not exercisable yet expected to vest	22,800
Weighted-average remaining contractual term	6 months
Pre-tax compensation costs expected to recognize	$ 61,000
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	68,273	68,457
Weighted-average remaining contractual term	1 year
Pre-tax compensation costs	$ 1,211,000
Number of units released	494
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	52,829
Weighted-average remaining contractual term	1 year 2 months 12 days
Pre-tax compensation costs	$ 608,000
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	79,244
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	446,400
Options available for grant under the plan	526,418
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	121,102
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 Equi109

Stock Options and Other Equity-Based Incentive Instruments - Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding, Number of Shares, beginning balance	446,400
Options granted, Number of Shares	0
Options exercised, Number of Shares	0
Options forfeited, Number of Shares	0
Options outstanding, Number of Shares, ending balance	446,400
Options outstanding, Weighted Average Exercise Price, beginning balance	$ 16.84
Options granted, Weighted Average Exercise Price	0
Options exercised, Weighted Average Exercise Price	0
Options forfeited, Weighted Average Exercise Price	0
Options outstanding, Weighted Average Exercise Price, ending balance	$ 16.84
Options Outstanding, Value on Date of Grant	$ 0	$ 0
Options granted, Weighted Average Fair Value	$ 0
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	0
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	0
Options forfeited, Option Price per Share	0
Options outstanding, Option Price per Share, ending balance	$ 23.21

Stock Options and Other Equi110

Stock Options and Other Equity-Based Incentive Instruments - Summary of Options Outstanding (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of options	446,400	446,400
Weighted average exercise price	$ 16.84	$ 16.84
Intrinsic value (in thousands)	$ 9,096
Weighted average remaining contractual term (yrs.)	3 years 8 months 12 days
Currently Exercisable [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of options	423,600
Weighted average exercise price	$ 16.65
Intrinsic value (in thousands)	$ 8,713
Weighted average remaining contractual term (yrs.)	3 years 7 months 6 days
Currently Not Exercisable [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of options	22,800
Weighted average exercise price	$ 20.45
Intrinsic value (in thousands)	$ 382
Weighted average remaining contractual term (yrs.)	5 years 6 months

Stock Options and Other Equi111

Stock Options and Other Equity-Based Incentive Instruments - Restricted Stock Unit (RSU) Activity (Detail) - Restricted Stock Units (RSUs) [Member]	3 Months Ended
	Mar. 31, 2018$ / 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	52,829
RSUs granted, Number of RSUs	0
RSUs forfeited/expired, Number of RSUs	0
RSUs outstanding, Number of RSUs, ending balance	52,829
RSUs granted, Weighted Average Fair Value on Date of Grant | $ / shares	$ 0
Service Condition Vesting RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs outstanding, Number of RSUs, beginning balance	68,457
RSUs granted, Number of RSUs	0
RSUs added through dividend credits, Number of RSUs	310
RSUs released, Number of RSUs	(494)
RSUs forfeited/expired, Number of RSUs	0
RSUs outstanding, Number of RSUs, ending balance	68,273
RSUs granted, Weighted Average Fair Value on Date of Grant | $ / shares	$ 0

Noninterest Income and Expen112

Noninterest Income and Expense - Components of Other Noninterest Income (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017
Income Statement [Abstract]
Service charges on deposit accounts	$ 3,779				$ 3,619
ATM and interchange fees	4,235				4,015
Other service fees	714				765
Mortgage banking service fees	517				521
Change in value of mortgage servicing rights	111				(13)
Total service charges and fees	9,356				8,907
Commissions on sale of non-deposit investment products	876				607
Gain on sale of loans	626				910
Increase in cash value of life insurance	608				685
Gain on sale of foreclosed assets	371				118
Lease brokerage income	128				206
Sale of customer checks	101				104
Change in indemnification asset					(221)
Life insurance proceeds in excess of cash value					107
Loss on disposal of fixed assets	(13)
Loss on marketable equity securities	(47)
Other	284				280
Total other noninterest income	2,934				2,796
Total noninterest income	$ 12,290	$ 12,478	$ 12,930	$ 12,910	$ 11,703

Noninterest Income and Expen113

Noninterest Income and Expense - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Mortgage loan servicing fees, net of change in fair value of mortgage loan servicing rights	$ 628,000	$ 508,000

Noninterest Income and Expen114

Noninterest Income and Expense - Components of Noninterest Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017
Schedule Of Other Noninterest Income And Expense [Line Items]
Base salaries, net of deferred loan origination costs	$ 13,962				$ 13,390
Incentive compensation	2,452				2,198
Benefits and other compensation costs	5,238				5,305
Total salaries and benefits expense	21,652				20,893
Occupancy	2,681				2,692
Data processing and software	2,514				2,396
Equipment	1,551				1,723
ATM and POS network charges	1,226				853
Advertising	838				967
Professional fees	773				766
Telecommunications	701				643
Change in reserve for unfunded commitments	700				15
Merger and acquisition expense	476
Assessments	430				405
Postage	358				404
Intangible amortization	339				359
Operational losses	294				435
Courier service	267				254
Provision for (reversal of) foreclosed asset losses	90				(66)
Foreclosed assets expense	24				38
Other miscellaneous expense	3,248				3,045
Total other noninterest expense	16,510				14,929
Total noninterest expense	38,162	$ 38,076	$ 37,222	$ 35,904	$ 35,822
Total merger and acquisition expense	476
North Valley Bancorp [Member]
Schedule Of Other Noninterest Income And Expense [Line Items]
Professional fees	355
Advertising and marketing	8
Other miscellaneous expense	$ 112

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Effective Tax Rate and Statutory Federal Income Tax Rate (Detail)	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Federal statutory income tax rate	21.00%	35.00%	35.00%
State income taxes, net of federal tax benefit	9.00%	6.90%
Tax-exempt interest on municipal obligations	(1.10%)	(1.90%)
Increase in cash value of insurance policies	(0.70%)	(1.40%)
Low income housing tax credits	(1.00%)	(0.60%)
Equity compensation		(0.50%)
Nondeductible merger expenses	0.40%
Nondeductible joint beneficiary agreement expense	0.10%	0.10%
Other	0.40%	0.20%
Effective Tax Rate	28.10%	37.80%

Earnings Per Share - Computatio

Earnings Per Share - Computation of Earnings Per Share (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017
Earnings Per Share [Abstract]
Net income	$ 13,910	$ 2,989	$ 11,897	$ 13,589	$ 12,079
Average number of common shares outstanding	22,956				22,870
Effect of dilutive stock options and restricted stock	327				362
Average number of common shares outstanding used to calculate diluted earnings per share	23,283				23,232
Options excluded from diluted earnings per share because the effect of these options was antidilutive	0				0

Comprehensive Income - Componen

Comprehensive Income - Components of Other Comprehensive Income and Related Tax Effects (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized holding gains (losses) on available for sale securities before reclassifications	$ (15,265)	$ 787
Amounts reclassified out of accumulated other comprehensive income:
Total amounts reclassified out of accumulated other comprehensive income	(363)
Unrealized holding gains (losses) on available for sale securities after reclassifications	(15,628)	787
Tax effect	4,602	(330)
Unrealized holding gains (losses) on available for sale securities, net of tax	(11,026)	457
Change in unfunded status of the supplemental retirement plans before reclassifications	667
Amounts reclassified out of accumulated other comprehensive income:
Amortization of prior service cost	(13)	(3)
Amortization of actuarial losses	127	96
Total amounts reclassified out of accumulated other comprehensive income	(554)	93
Change in unfunded status of the supplemental retirement plans after reclassifications	113	93
Tax effect	(33)	(39)
Change in unfunded status of the supplemental retirement plans, net of tax	80	54
Change in joint beneficiary agreement liability before reclassifications	0	0
Amounts reclassified out of accumulated other comprehensive income	0	0
Change in joint beneficiary agreement liability after reclassifications	0	0
Tax effect	0	0
Change in joint beneficiary agreement liability, net of tax	0	0
Other comprehensive income (loss)	(10,946)	$ 511
ASU 2016-01 [Member]
Amounts reclassified out of accumulated other comprehensive income:
Total amounts reclassified out of accumulated other comprehensive income	62
ASU 2018-02 [Member]
Amounts reclassified out of accumulated other comprehensive income:
Total amounts reclassified out of accumulated other comprehensive income	(425)
Amounts reclassified out of accumulated other comprehensive income:
Total amounts reclassified out of accumulated other comprehensive income	$ (668)

Comprehensive Income - Compo118

Comprehensive Income - Components of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	$ (17,205)	$ (5,228)	$ (7,402)
Net Unrealized Loss on Available For Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss, before tax	(18,975)		(8,083)
Accumulated other comprehensive loss, tax effect	5,610		3,399
Accumulated other comprehensive loss	(13,365)		(4,684)
Unfunded Status of Supplemental Retirement Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss, before tax	(5,238)		(4,621)
Accumulated other comprehensive loss, tax effect	1,549		1,943
Accumulated other comprehensive loss	(3,689)		(2,678)
Joint Beneficiary Agreement Liability [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss, before tax	(151)		(40)
Accumulated other comprehensive loss	$ (151)		$ (40)

Retirement Plans - Additional I

Retirement Plans - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Salaries & benefits expense	$ 21,652,000	$ 20,893,000
Employee service period under ESOP	1 year
Contribution and paid out as benefits under ESOP	$ 465,000	525,000
Deferred compensation obligations	6,809,000			$ 6,605,000
Earnings credits on deferred balances included in noninterest expense	$ 124,000	145,000
401(k) Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
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	$ 203,000	186,000
Employer's contribution to retirement plan	199,000	179,000
Supplemental Retirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer's contribution to retirement plan	$ 267,000	$ 259,000
Supplemental Retirement Plans [Member] | Scenario, Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer's contribution to retirement plan			$ 1,106,000

Retirement Plans - Net Periodic

Retirement Plans - Net Periodic Benefit Cost Recognized for Supplemental Retirement Plans (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Net pension cost included the following components:
Service cost-benefits earned during the period	$ 243	$ 235
Interest cost on projected benefit obligation	237	249
Amortization of net obligation at transition	1	1
Amortization of prior service cost	(13)	(3)
Recognized net actuarial loss	127	96
Net periodic pension cost	$ 595	$ 578

Related Party Transactions - Su

Related Party Transactions - Summary of Activity in Lending Transactions (Detail) - Directors and Officers [Member] - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Beginning balance	$ 2,148	$ 2,432
Advances/new loans	145	437
Removed/payments	(314)	(721)
Ending balance	$ 1,979	$ 2,148

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Related Party Transactions [Abstract]
Bank deposits of directors, officers and other related parties	$ 30,871,000	$ 46,025,000

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	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	$ 745,738	$ 737,570
Marketable Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	2,890	2,938
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	616,657	604,789
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	119,238	123,156
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	2,890	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	2,890	2,938
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	735,895	727,945
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	616,657	604,789
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	119,238	123,156
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	6,953	6,687
Mortgage Servicing Rights [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	6,953	6,687
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	$ 6,953	$ 6,687

Fair Value Measurement - Additi

Fair Value Measurement - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
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

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	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 6,687	$ 6,595
Transfers into (out of) Level 3	0	0
Change Included in Earnings	111	(13)
Issuances	155	278
Ending Balance	$ 6,953	$ 6,860

Fair Value Measurement - Quanti

Fair Value Measurement - Quantitative Information about Recurring Level 3 Fair Value Measurements (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Constant prepayment rate	7.50%	8.30%
Discount rate	13.00%	14.00%
Mortgage Servicing Rights [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortgages Servicing Rights, Fair Value	$ 6,953	$ 6,860	$ 6,687	$ 6,595
Minimum [Member] | Mortgage Servicing Rights [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate	11.00%		13.00%
Minimum [Member] | Mortgage Servicing Rights [Member] | Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Constant prepayment rate	6.00%		6.20%
Maximum [Member] | Mortgage Servicing Rights [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate	15.00%		15.00%
Maximum [Member] | Mortgage Servicing Rights [Member] | Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Constant prepayment rate	19.70%		22.00%
Weighted Average [Member] | Mortgage Servicing Rights [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate	13.00%		13.00%
Weighted Average [Member] | Mortgage Servicing Rights [Member] | Discounted Cash Flow [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Constant prepayment rate	7.50%		8.90%

Fair Value Measurement - Assets

Fair Value Measurement - Assets and Liabilities Measured at Fair Value on Nonrecurring Basis (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Impaired Originated & PNCI Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	$ 2,103		$ 2,767
Fair Value Nonrecurring Basis [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	2,877	$ 2,352	4,984
Total Gains/(Losses)	(882)	8	(1,587)
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	2,103	824	2,767
Total Gains/(Losses)	(795)	30	(1,452)
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	774	1,528	2,217
Total Gains/(Losses)	(87)	(22)	(135)
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	2,877	2,352	4,984
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	2,103	824	2,767
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	$ 774	$ 1,528	$ 2,217

Fair Value Measurement - Qua128

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	Mar. 31, 2018	Dec. 31, 2017
Impaired Originated & PNCI Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 2,103	$ 2,767
Foreclosed Assets [Member] | Land & Construction [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	190	1,341
Foreclosed Assets [Member] | Residential Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	492	622
Foreclosed Assets [Member] | Commercial Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 92	$ 254

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 ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financial assets:
Cash and due from banks	$ 87,138	$ 105,968
Cash at Federal Reserve and other banks	95,841	99,460
Securities held to maturity	496,035	514,844
Financial liabilities:
Other borrowings	65,041	122,166
Junior subordinated debt	56,905	56,858
Level 3 [Member] | Overdraft Privilege Commitments [Member]
Off-balance sheet:
Contract amount, Off-balance sheet	101,411	98,260
Level 3 [Member] | Standby Letters of Credit [Member]
Off-balance sheet:
Contract amount, Off-balance sheet	11,573	13,075
Level 3 [Member] | Commitments [Member]
Off-balance sheet:
Contract amount, Off-balance sheet	1,001,059	933,542
Fair Value [Member] | Level 3 [Member]
Financial assets:
Loans, net	3,025,636	2,992,225
Financial liabilities:
Junior subordinated debt	59,982	58,466
Fair Value [Member] | Level 3 [Member] | Overdraft Privilege Commitments [Member]
Off-balance sheet:
Fair value, Off-balance sheet	1,014	983
Fair Value [Member] | Level 3 [Member] | Standby Letters of Credit [Member]
Off-balance sheet:
Fair value, Off-balance sheet	116	131
Fair Value [Member] | Level 3 [Member] | Commitments [Member]
Off-balance sheet:
Fair value, Off-balance sheet	10,011	9,335
Fair Value [Member] | Level 1 [Member]
Financial assets:
Cash and due from banks	87,138	105,968
Cash at Federal Reserve and other banks	95,841	99,460
Fair Value [Member] | Level 2 [Member]
Financial assets:
Securities held to maturity	488,639	518,165
Loans held for sale	2,149	4,616
Financial liabilities:
Deposits	4,081,089	4,006,620
Other borrowings	65,041	122,166
Carrying Amount [Member] | Level 3 [Member]
Financial assets:
Loans, net	3,039,760	2,984,842
Financial liabilities:
Junior subordinated debt	56,905	56,858
Carrying Amount [Member] | Level 1 [Member]
Financial assets:
Cash and due from banks	87,138	105,968
Cash at Federal Reserve and other banks	95,841	99,460
Carrying Amount [Member] | Level 2 [Member]
Financial assets:
Securities held to maturity	496,035	514,844
Restricted equity securities	16,956	16,956
Loans held for sale	2,149	4,616
Financial liabilities:
Deposits	4,084,404	4,009,131
Other borrowings	$ 65,041	$ 122,166

TriCo Bancshares Condensed F130

TriCo Bancshares Condensed Financial Statements (Parent Only) - Condensed Balance Sheets (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Assets
Cash and cash equivalents	$ 182,979	$ 205,428	$ 323,706	$ 305,612
Other assets	56,274	55,051
Total assets	4,779,957	4,761,315
Liabilities and shareholders' equity
Other liabilities	63,529	63,258
Junior subordinated debt	56,905	56,858
Total liabilities	4,274,701	4,255,507
Shareholders' equity:
Preferred stock, no par value: 1,000,000 shares authorized, zero issued and outstanding at March 31, 2018 and December 31, 2017
Common stock, no par value: authorized 50,000,000 shares; issued and outstanding 22,956,323 and 22,955,963 shares, respectively	256,226	255,836
Retained earnings	266,235	255,200
Accumulated other comprehensive loss, net	(17,205)	(5,228)	(7,402)
Total shareholders' equity	505,256	505,808	486,718	477,347
Total liabilities and shareholders' equity	4,779,957	4,761,315
Parent [Member]
Assets
Cash and cash equivalents	3,516	3,924	$ 2,840	$ 2,802
Investment in Tri Counties Bank	557,380	557,538
Other assets	1,758	1,721
Total assets	562,654	563,183
Liabilities and shareholders' equity
Other liabilities	493	517
Junior subordinated debt	56,905	56,858
Total liabilities	57,398	57,375
Shareholders' equity:
Preferred stock, no par value: 1,000,000 shares authorized, zero issued and outstanding at March 31, 2018 and December 31, 2017
Common stock, no par value: authorized 50,000,000 shares; issued and outstanding 22,956,323 and 22,955,963 shares, respectively	256,226	255,836
Retained earnings	266,235	255,200
Accumulated other comprehensive loss, net	(17,205)	(5,228)
Total shareholders' equity	505,256	505,808
Total liabilities and shareholders' equity	$ 562,654	$ 563,183

TriCo Bancshares Condensed F131

TriCo Bancshares Condensed Financial Statements (Parent Only) - Condensed Balance Sheets (Parenthetical) (Detail) - $ / shares	Mar. 31, 2018	Dec. 31, 2017	Aug. 21, 2007
Condensed Financial Statements, Captions [Line Items]
Preferred stock, par value	$ 0	$ 0
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0	$ 0
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	22,956,323	22,955,963
Common stock, shares outstanding	22,956,323	22,955,963	15,814,662
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Preferred stock, par value	$ 0	$ 0
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0	$ 0
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	22,956,323	22,955,963
Common stock, shares outstanding	22,956,323	22,955,963

TriCo Bancshares Condensed F132

TriCo Bancshares Condensed Financial Statements (Parent Only) - Condensed Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Interest expense	$ (2,135)	$ (1,868)	$ (1,829)	$ (1,610)	$ (1,491)
Income before income taxes	19,350	17,818	19,027	21,236	19,431
Equity in net income of Tri Counties Bank:
Income tax benefit	(5,440)	(14,829)	(7,130)	(7,647)	(7,352)
Net income	13,910	$ 2,989	$ 11,897	$ 13,589	12,079
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Interest expense	(697)				(595)
Administration expense	(426)				(159)
Income before income taxes	(1,123)				(754)
Equity in net income of Tri Counties Bank:
Distributed	4,372				4,042
Undistributed	10,397				8,474
Income tax benefit	264				317
Net income	$ 13,910				$ 12,079

TriCo Bancshares Condensed F133

TriCo Bancshares Condensed Financial Statements (Parent Only) - Condensed Statements of Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Net income	$ 13,910	$ 2,989	$ 11,897	$ 13,589	$ 12,079
Other comprehensive income (loss), net of tax:
Unrealized gains (losses) on available for sale securities arising during the period	(11,026)				457
Change in minimum pension liability	80				54
Other comprehensive income (loss)	(10,946)				511
Comprehensive income	2,964				12,590
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	13,910				12,079
Other comprehensive income (loss), net of tax:
Unrealized gains (losses) on available for sale securities arising during the period	(11,026)				457
Change in minimum pension liability	80				54
Other comprehensive income (loss)	(10,946)				511
Comprehensive income	$ 2,964				$ 12,590

TriCo Bancshares Condensed F134

TriCo Bancshares Condensed Financial Statements (Parent Only) - Condensed Statements of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017
Operating activities:
Net income	$ 13,910	$ 2,989	$ 11,897	$ 13,589	$ 12,079
Adjustments to reconcile net income to net cash provided by operating activities:
Equity compensation vesting expense	391				381
Net cash from operating activities	23,714				19,444
Financing activities:
Repurchase of common stock					(169)
Cash dividends paid - common	(3,903)				(3,431)
Net cash used by financing activities	14,245				(2,572)
Net change in cash and cash equivalents	(22,449)				18,094
Cash and cash equivalents and beginning of year	205,428			323,706	305,612
Cash and cash equivalents at end of year	182,979	205,428			323,706
Parent [Member]
Operating activities:
Net income	13,910				12,079
Adjustments to reconcile net income to net cash provided by operating activities:
Undistributed equity in earnings of Tri Counties Bank	(10,397)				(8,474)
Equity compensation vesting expense	391				381
Stock option excess tax benefits	0				0
Net change in other assets and liabilities	(405)				(348)
Net cash from operating activities	3,499				3,638
Financing activities:
Repurchase of common stock	(4)				(169)
Cash dividends paid - common	(3,903)				(3,431)
Net cash used by financing activities	(3,907)				(3,600)
Net change in cash and cash equivalents	(408)				38
Cash and cash equivalents and beginning of year	3,924			$ 2,840	2,802
Cash and cash equivalents at end of year	$ 3,516	$ 3,924			$ 2,840

Regulatory Matters - Additional

Regulatory Matters - Additional Information (Detail)	Dec. 31, 2019	Mar. 31, 2018	Dec. 31, 2017
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Increase in risk-based capital ratios		0.625%
Basel III Phase-in Schedule [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Minimum capital level requirements, Total capital ratio		1.875%	1.25%
Scenario, Forecast [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Minimum capital level requirements, Total capital ratio	10.50%
Minimum capital level requirements, Tier 1 capital ratio	8.50%
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%

Regulatory Matters - Actual and

Regulatory Matters - Actual and Required Capital Ratios of Bank (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Capitalization [Line Items]
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%
Basel III Phase-in Schedule [Member]
Schedule of Capitalization [Line Items]
Total Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	1.875%	1.25%
Parent [Member]
Schedule of Capitalization [Line Items]
Total Capital (to Risk Weighted Assets), Actual, Amount	$ 539,966	$ 528,805
Tier 1 Capital (to Risk Weighted Assets), Actual, Amount	506,129	495,318
Common Equity Tier 1 Capital (to Risk Weighted Assets), Actual, Amount	450,933	440,643
Tier 1 Capital (to Average Assets), Actual, Amount	$ 506,129	$ 495,318
Total Capital (to Risk Weighted Assets), Actual, Ratio	13.91%	14.07%
Tier 1 Capital (to Risk Weighted Assets), Actual, Ratio	13.03%	13.18%
Common Equity Tier 1 Capital (to Risk Weighted Assets), Actual, Ratio	11.61%	11.72%
Tier 1 Capital (to Average Assets), Actual, Ratio	10.84%	10.80%
Parent [Member] | Basel III Phase-in Schedule [Member]
Schedule of Capitalization [Line Items]
Total Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	$ 383,434	$ 347,694
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	305,777	272,517
Common Equity Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	247,534	216,134
Tier 1 Capital (to Average Assets), Minimum Capital Requirement, Amount	$ 186,720	$ 183,400
Total Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	9.875%	9.25%
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	7.875%	7.25%
Common Equity Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	6.375%	5.75%
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	$ 407,702	$ 394,679
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	330,045	319,502
Common Equity Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	271,802	263,120
Tier 1 Capital (to Average Assets), Minimum Capital Requirement, Amount	$ 186,720	$ 183,400
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%
Tri Countries Bank [Member]
Schedule of Capitalization [Line Items]
Total Capital (to Risk Weighted Assets), Actual, Amount	$ 536,894	$ 525,384
Tier 1 Capital (to Risk Weighted Assets), Actual, Amount	503,057	491,897
Common Equity Tier 1 Capital (to Risk Weighted Assets), Actual, Amount	503,057	491,897
Tier 1 Capital (to Average Assets), Actual, Amount	$ 503,057	$ 491,897
Total Capital (to Risk Weighted Assets), Actual, Ratio	13.83%	13.98%
Tier 1 Capital (to Risk Weighted Assets), Actual, Ratio	12.96%	13.09%
Common Equity Tier 1 Capital (to Risk Weighted Assets), Actual, Ratio	12.96%	13.09%
Tier 1 Capital (to Average Assets), Actual, Ratio	10.78%	10.73%
Total Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 388,112	$ 375,713
Tier 1 Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	310,490	300,570
Common Equity Tier 1 Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	252,273	244,214
Tier 1 Capital (to Average Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	233,395	229,243
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	383,261	347,535
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	305,638	272,392
Common Equity Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	247,421	216,035
Tier 1 Capital (to Average Assets), Minimum Capital Requirement, Amount	$ 186,716	$ 183,394
Total Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	9.875%	9.25%
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	7.875%	7.25%
Common Equity Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	6.375%	5.75%
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	$ 407,518	$ 394,499
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	329,895	319,356
Common Equity Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	271,678	262,999
Tier 1 Capital (to Average Assets), Minimum Capital Requirement, Amount	$ 186,716	$ 183,394
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%

Summary of Quarterly Results137

Summary of Quarterly Results of Operations (Unaudited) - Results of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017
Loans:
Discount accretion PCI - cash basis	$ 246	$ 516	$ 398	$ 386	$ 112
Discount accretion PCI - other	60	445	407	797	631
Discount accretion PNCI	326	528	559	987	798
All other loan interest income	37,417	36,705	35,904	34,248	33,373
Total loan interest income	38,049	38,194	37,268	36,418	34,914
Debt securities, dividends and interest bearing cash at banks (not FTE)	9,072	8,767	8,645	8,626	8,570
Total interest and dividend income	47,121	46,961	45,913	45,044	43,484
Interest expense	2,135	1,868	1,829	1,610	1,491
Net interest income	44,986	45,093	44,084	43,434	41,993
Provision for (benefit from reversal of provision for) loan losses	(236)	1,677	765	(796)	(1,557)
Net interest income after provision for loan losses	45,222	43,416	43,319	44,230	43,550
Noninterest income	12,290	12,478	12,930	12,910	11,703
Noninterest expense	38,162	38,076	37,222	35,904	35,822
Income before income taxes	19,350	17,818	19,027	21,236	19,431
Income tax expense	5,440	14,829	7,130	7,647	7,352
Net income	$ 13,910	$ 2,989	$ 11,897	$ 13,589	$ 12,079
Per common share:
Net income (diluted)	$ 0.60	$ 0.13	$ 0.51	$ 0.58	$ 0.52
Dividends	$ 0.17	$ 0.17	$ 0.17	$ 0.17	$ 0.15