Bank of Marin Bancorp (BMRC) 10-Q 8 May 18 2018 Q1 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2018	Apr. 30, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	Bank of Marin Bancorp
Entity Central Index Key	1,403,475
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		6,983,918

CONSOLIDATED STATEMENTS OF COND

CONSOLIDATED STATEMENTS OF CONDITION - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets
Cash and due from banks	$ 159,347	$ 203,545
Investment securities
Held-to-maturity, at amortized cost	149,013	151,032
Available-for-sale, at fair value	423,882	332,467
Total investment securities	572,895	483,499
Loans, net of allowance for loan losses of $15,771 and $15,767 at March 31, 2018 and December 31, 2017, respectively	1,655,969	1,663,246
Bank premises and equipment, net	8,297	8,612
Goodwill	30,140	30,140
Core deposit intangible	6,262	6,492
Interest receivable and other assets	77,133	72,620
Total assets	2,510,043	2,468,154
Deposits
Non-interest bearing	1,065,470	1,014,103
Interest bearing
Transaction accounts	166,117	169,195
Savings accounts	180,730	178,473
Money market accounts	628,335	626,783
Time accounts	145,942	160,116
Total deposits	2,186,594	2,148,670
Subordinated debentures	5,772	5,739
Interest payable and other liabilities	19,213	16,720
Total liabilities	2,211,579	2,171,129
Stockholders' Equity
Preferred stock, no par value, Authorized - 5,000,000 shares, none issued	0	0
Common stock, no par value, Authorized - 15,000,000 shares; Issued and outstanding - 6,989,126 and 6,921,542 at March 31, 2018 and December 31, 2017, respectively	145,282	143,967
Retained earnings	160,556	155,544
Accumulated other comprehensive loss, net of taxes	(7,374)	(2,486)
Total stockholders' equity	298,464	297,025
Total liabilities and stockholders' equity	$ 2,510,043	$ 2,468,154

CONSOLIDATED STATEMENTS OF CON3

CONSOLIDATED STATEMENTS OF CONDITION (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Loans and Leases Receivable, Net Amount
Loans, allowance for loan losses	$ 15,771	$ 15,767
Stockholders' Equity
Preferred stock, no par value (in dollars per share)	$ 0	$ 0
Preferred stock, authorized (in shares)	5,000,000	5,000,000
Preferred stock, issued (in shares)	0	0
Common stock, no par value (in dollars per share)	$ 0	$ 0
Common stock, authorized (in shares)	15,000,000	15,000,000
Common stock, issued (in shares)	6,989,126	6,921,542
Common stock, outstanding (in shares)	6,989,126	6,921,542

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Interest income
Interest and fees on loans	$ 18,887	$ 15,849
Interest on investment securities
Securities of U.S. government agencies	2,475	1,518
Obligations of state and political subdivisions	638	568
Corporate debt securities and other	44	37
Interest on Federal funds sold and due from banks	403	60
Total interest income	22,447	18,032
Interest expense
Interest on interest-bearing transaction accounts	52	29
Interest on savings accounts	18	15
Interest on money market accounts	216	113
Interest on time accounts	156	146
Interest on subordinated debentures	114	108
Total interest expense	556	411
Net interest income	21,891	17,621
Provision for loan losses	0	0
Net interest income after provision for loan losses	21,891	17,621
Non-interest income
Service charges on deposit accounts	477	452
Wealth Management and Trust Services	515	503
Debit card interchange fees	396	372
Merchant interchange fees	80	96
Earnings on bank-owned life insurance	228	209
Dividends on FHLB stock	196	232
Other income	350	251
Total non-interest income	2,242	2,115
Non-interest expense
Salaries and related benefits	9,017	7,475
Occupancy and equipment	1,507	1,319
Depreciation and amortization	547	481
Federal Deposit Insurance Corporation insurance	191	161
Data processing	1,381	939
Professional services	1,299	522
Directors' expense	174	158
Information technology	269	198
Provision for losses on off-balance sheet commitments	0	165
Other expense	1,696	1,593
Total non-interest expense	16,081	13,011
Income before provision for income taxes	8,052	6,725
Provision for income taxes	1,663	2,177
Net income	$ 6,389	$ 4,548
Net income per common share:
Basic (usd per share)	$ 0.92	$ 0.75
Diluted (usd per share)	$ 0.91	$ 0.74
Weighted average shares:
Basic (shares)	6,914	6,092
Diluted (shares)	7,006	6,172
Dividends declared per common share (usd per share)	$ 0.29	$ 0.27
Comprehensive income:
Net income	$ 6,389	$ 4,548
Other comprehensive (loss) income
Change in net unrealized gain or loss on available-for-sale securities	(6,170)	4,710
Net unrealized loss on securities transferred from available-for-sale to held-to-maturity	0	(3,036)
Amortization of net unrealized losses on securities transferred from available-for-sale to held-to-maturity	136	41
Subtotal	(6,034)	1,715
Deferred tax (benefit) expense	(1,784)	704
Other comprehensive (loss) income, net of tax	(4,250)	1,011
Comprehensive income	$ 2,139	$ 5,559

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Retained Earnings	Accumulated Other Comprehensive Loss (AOCI), Net of Taxes
Balance (in shares) at Dec. 31, 2016		6,127,314
Balance at Dec. 31, 2016	$ 230,563	$ 87,392	$ 146,464	$ (3,293)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	15,976		15,976
Other comprehensive income (loss)	807			807
Stock options exercised, net of shares surrendered for cashless exercises and tax withholdings (in shares)		9,266
Stock options exercised, net of shares surrendered for cashless exercises and tax withholdings	28	$ 28
Stock issued under employee stock purchase plan (in shares)		512
Stock issued under employee stock purchase plan	32	$ 32
Stock issued under employee stock ownership plan (ESOP) (in shares)		29,547
Stock issued under employee stock ownership plan (ESOP)	1,850	$ 1,850
Restricted stock granted (in shares)		16,230
Restricted stock granted		$ 0
Restricted stock forfeited / cancelled (in shares)		0
Restricted stock forfeited / cancelled		$ 0
Stock-based compensation - stock options	529	529
Stock-based compensation - restricted stock	742	$ 742
Cash dividends paid on common stock	(6,896)		(6,896)
Stock purchased by directors under director stock plan (in shares)		531
Stock purchased by directors under director stock plan	35	$ 35
Stock issued in payment of director fees (in shares)		2,878
Stock issued in payment of director fees	188	$ 188
Stock and stock options issued to Bank of Napa shareholders (net of payment for fractional shares of $14 thousand) (in shares)		735,264
Stock and stock options issued to Bank of Napa shareholders (net of payment for fractional shares of $14 thousand)	$ 53,171	$ 53,171
Balance (in shares) at Dec. 31, 2017	6,921,542	6,921,542
Balance at Dec. 31, 2017	$ 297,025	$ 143,967	155,544	(2,486)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	6,389		6,389
Other comprehensive income (loss)	(4,250)			(4,250)
Reclassification of stranded tax effects in AOCI			638	(638)
Stock options exercised, net of shares surrendered for cashless exercises and tax withholdings (in shares)		47,787
Stock options exercised, net of shares surrendered for cashless exercises and tax withholdings	453	$ 453
Stock issued under employee stock purchase plan (in shares)		152
Stock issued under employee stock purchase plan	10	$ 10
Restricted stock granted (in shares)		18,520
Restricted stock surrendered for tax withholdings upon vesting (in shares)		(401)
Restricted stock surrendered for tax withholdings upon vesting	(28)	$ (28)
Restricted stock forfeited / cancelled (in shares)		(4,077)
Stock-based compensation - stock options	316	$ 316
Stock-based compensation - restricted stock	455	$ 455
Cash dividends paid on common stock	(2,015)		(2,015)
Stock purchased by directors under director stock plan (in shares)		260
Stock purchased by directors under director stock plan	18	$ 18
Stock issued in payment of director fees (in shares)		1,343
Stock issued in payment of director fees	$ 91	$ 91
Balance (in shares) at Mar. 31, 2018	6,989,126	6,985,126
Balance at Mar. 31, 2018	$ 298,464	$ 145,282	$ 160,556	$ (7,374)

CONSOLIDATED STATEMENTS OF CHA6

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Statement of Stockholders' Equity [Abstract]
Fractional shares issued in acquisition, payment	$ 14

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Cash Flows from Operating Activities:
Net income	$ 6,389	$ 4,548	$ 15,976
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for losses on off-balance sheet commitments	0	165
Noncash director compensation expense - common stock	67	73
Stock-based compensation expense	771	378
Amortization of core deposit intangible	230	118
Amortization of investment security premiums, net of accretion of discounts	762	762
Accretion of discount on acquired loans	(211)	(240)
Accretion of discount on subordinated debentures	33	42
Net change in deferred loan origination costs/fees	(110)	75
Gain on sales of other real estate owned	0	(1)
Depreciation and amortization	547	481
Earnings on bank-owned life insurance policies	(228)	(209)
Net change in operating assets and liabilities:
Deferred rent and other rent-related expenses	(86)	145
Interest receivable and other assets	(2,339)	1,305
Interest payable and other liabilities	3,374	(674)
Total adjustments	2,810	2,420
Net cash provided by operating activities	9,199	6,968
Cash Flows from Investing Activities:
Purchase of held-to-maturity securities	(1,989)	(2,991)
Purchase of available-for-sale securities	(109,693)	(5,590)
Proceeds from paydowns/maturities of held-to-maturity securities	3,917	4,001
Proceeds from paydowns/maturities of available-for-sale securities	11,572	8,594
Loans originated and principal collected, net	7,022	8,875
Purchase of premises and equipment	(232)	(297)
Proceeds from sale of other real estate owned or repossessed assets	0	170
Cash paid for low-income housing tax credit investment	(356)	(345)
Net cash (used in) provided by investing activities	(89,759)	12,417
Cash Flows from Financing Activities:
Net increase in deposits	37,924	6,569
Proceeds from stock options exercised	504	88
Payment of tax withholdings for stock options exercised and vesting of restricted stock	(79)	(60)
Proceeds from stock issued under employee and director stock purchase plans	28	31
Cash dividends paid on common stock	(2,015)	(1,655)
Net cash provided by financing activities	36,362	4,973
Net (decrease) increase in cash and cash equivalents	(44,198)	24,358
Cash and cash equivalents at beginning of period	203,545	48,804	48,804
Cash and cash equivalents at end of period	159,347	73,162	203,545
Supplemental disclosure of cash flow information:
Cash paid in interest	543	373
Supplemental disclosure of noncash investing and financing activities:
Change in net unrealized gain or loss on available-for-sale securities	(6,034)	1,674
Securities transferred from available-for-sale to held-to-maturity	0	128,965	129,000
Amortization of net unrealized loss on available-for-sale securities transferred to held-to-maturity	136	41	$ 41
Subscription in low income housing tax credit investment	(3,000)	0
Stock issued in payment of director fees	$ 91	$ 82

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The consolidated financial statements include the accounts of Bank of Marin Bancorp (“Bancorp”), a bank holding company, and its wholly-owned bank subsidiary, Bank of Marin (the “Bank”), a California state-chartered commercial bank. References to “we,” “our,” “us” mean Bancorp and the Bank that are consolidated for financial reporting purposes. The accompanying unaudited consolidated interim financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission ("SEC"). Certain information and note disclosures normally included in annual financial statements prepared in accordance with U.S. generally accepted accounting principles ("GAAP") have been condensed or omitted pursuant to those rules and regulations. Although we believe that the disclosures are adequate and the information presented is not misleading, we suggest that these interim financial statements be read in conjunction with the annual financial statements and the notes thereto included in our 2017 Annual Report on Form 10-K. In the opinion of Management, the unaudited consolidated financial statements reflect all adjustments, which are necessary for a fair presentation of the consolidated financial position, the results of operations, changes in comprehensive income, changes in stockholders’ equity, and cash flows for the periods presented. All material intercompany transactions have been eliminated. The results of these interim periods may not be indicative of the results for the full year or for any other period. The NorCal Community Bancorp Trusts I and II, respectively (the "Trusts") were formed for the sole purpose of issuing trust preferred securities. Bancorp is not considered the primary beneficiary of the Trusts (variable interest entities), therefore the Trusts are not consolidated in our consolidated financial statements, but rather the subordinated debentures are shown as a liability on our consolidated statements of condition (See Note 6, Borrowings). Bancorp's investment in the securities of the Trusts is accounted for under the equity method and is included in i nterest receivable and other assets on the consolidated statements of condition. The following table shows: 1) weighted average basic shares, 2) potentially dilutive weighted average common shares related to stock options and unvested restricted stock awards, and 3) weighted average diluted shares. Basic earnings per share (“EPS”) are calculated by dividing net income by the weighted average number of common shares outstanding during each period, excluding unvested restricted stock awards. Diluted EPS are calculated using the weighted average number of potentially dilutive common shares. The number of potentially dilutive common shares included in year-to-date diluted EPS is a year-to-date weighted average of potentially dilutive common shares included in each quarterly diluted EPS computation. In computing diluted EPS, we exclude anti-dilutive shares such as options whose exercise prices exceed the current common stock price as they would not reduce EPS under the treasury method. We have two forms of outstanding common stock: common stock and unvested restricted stock awards. Holders of unvested restricted stock awards receive non-forfeitable dividends at the same rate as common shareholders and they both share equally in undistributed earnings. Under the two-class method, the difference in EPS is nominal for these participating securities. Three months ended (in thousands, except per share data) March 31, 2018 March 31, 2017 Weighted average basic shares outstanding 6,914 6,092 Potentially dilutive common shares related to: Stock options 75 62 Unvested restricted stock awards 17 18 Weighted average diluted shares outstanding 7,006 6,172 Net income $ 6,389 $ 4,548 Basic EPS $ 0.92 $ 0.75 Diluted EPS $ 0.91 $ 0.74 Weighted average anti-dilutive shares not included in the calculation of diluted EPS 32 13

Recently Issued Accounting Stan

Recently Issued Accounting Standards	3 Months Ended
	Mar. 31, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recently Issued Accounting Standards	Recently Adopted and Issued Accounting Standards Accounting Standards Adopted in 2018 In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers (Topic 606). The core principle of this ASU (and all subsequent updates) is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. This ASU establishes a five-step model that must be used to recognize revenue that requires the entity to 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 entity satisfies the performance obligation. The ASU does not apply to the majority of our revenue, including revenue associated with financial instruments, such as loans and investment securities, and certain non-interest income, such as earnings on bank-owned life insurance, dividends on Federal Home Loan Bank ("FHLB") stock, gains or losses on sales of investment securities, and deposit overdraft charges. The standard allowed the use of either the full retrospective or modified retrospective transition method. We elected to apply the modified retrospective transition method to incomplete contracts as of the initial date of application on January 1, 2018. The adoption of the new standards did not have a material impact on our financial condition or results of operations as the revenue recognition patterns under the new standards did not change significantly from our current practice of recognizing the in-scope non-interest income. In addition, we did not retroactively revise prior period amounts or record a cumulative adjustment to retained earnings upon adoption. We considered the nature, amount, timing, and uncertainty of revenue from contracts with customers and determined that significant revenue streams are sufficiently disaggregated in the consolidated statements of comprehensive income. Descriptions of our significant revenue-generating transactions that are within the scope of the new revenue recognition standards, which are presented in the consolidated statements of comprehensive income as components of non-interest income, are as follows: • Wealth Management & Trust ("WM&T") fees - WM&T services include, but are not limited to: customized investment advisory and management; administrative services such as bill pay and tax reporting; trust administration, estate settlement, custody and fiduciary services. Performance obligations for investment advisory and management services are generally satisfied over time. Revenue is recognized monthly according to a tiered fee schedule based on the client's month-end market value of assets under our management. WM&T does not earn revenue based on performance or incentives. Costs associated with WM&T revenue-generating activities, such as payments to sub-advisors, are recorded separately as part of professional service expenses when incurred. • Deposit account service charges - Service charges on deposit accounts consist of monthly maintenance fees, business account analysis fees, business online banking fees, check order charges, and other deposit account-related fees. Performance obligations for monthly maintenance fees and account analysis fees are satisfied, and the related revenue recognized, when our performance obligation is completed each month. Performance obligations related to transaction-based services (such as check orders) are satisfied, and the related revenue recognized, at a point in time when completed, except for business accounts subject to analysis where the transaction-based fees are part of the monthly account analysis fees. • Debit card interchange fees - We issue debit cards to our consumer and small business customers that allow them to purchase goods and services from merchants in person, online, or via mobile devices using funds held in their demand deposit accounts held with us. Debit cards issued to our customers are part of global electronic payment networks (such as Visa) who pass a portion of the merchant interchange fees to debit card-issuing member banks like us when our customers make purchases through their networks. Performance obligations for debit card services are satisfied, and revenue is recognized, daily as transactions are processed by the payment networks. Because we act in an agent capacity, we determined that network costs previously recorded as a component of non-interest expense should be netted with interchange fees recorded in non-interest income starting in the second quarter of 2018. Network costs were immaterial for the three months ended March 31, 2018 and 2017. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities . The amendments in this ASU make improvements to accounting standards related to financial instruments, including the following: • Requires equity investments, except for those accounted for under the equity method of accounting or those that result in consolidation of the investee, to be measured at fair value with changes in fair value recognized in net income. However, an entity may choose to measure equity investments that do not have readily determinable fair values at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. • Simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment. When impairment exists, an entity is required to measure the investment at fair value. • Eliminates the requirement to disclose the method(s) and significant assumptions used to estimate the fair value required under current standards for financial instruments measured at amortized cost on the consolidated balance sheet. • Requires public companies to use the exit price notion when measuring and disclosing the fair value of financial instruments. • Requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset (i.e., securities or loans and receivables) on the balance sheet or the accompanying notes to the financial statements. • Clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities in combination with the entity's other deferred tax assets. We adopted the requirements of this ASU effective January 1, 2018, which did not have a material impact on our financial condition and results of operations. The fair value of our loans held for investment, which is recorded at amortized cost, now incorporates the exit price notion reflecting factors such as a liquidity premium. See Note 3, Fair Value of Assets and Liabilities. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments . This ASU provides guidance on how to present and classify eight specific cash flow topics in the statement of cash flows. The ASU is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. The amendments should be applied using a retrospective transition method to each period presented, if practical. We adopted the requirements of this ASU effective January 1, 2018, which did not impact our financial condition, results of operations, or related financial statement disclosures for the periods presented. In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business . The amendments are intended to help companies evaluate whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses and provide a more robust framework to use in determining when a set of assets and activities is a business. The amendments should be applied prospectively and are effective for annual periods after December 31, 2017, including interim periods within those periods. We adopted the amendments effective January 1, 2018, which did not impact our financial condition, results of operations, or related financial statement disclosures in the first quarter of 2018. In May 2017, the FASB issued ASU No. 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting . This ASU applies to entities that change the terms or conditions of a share-based payment award. The FASB adopted this ASU to provide clarity in what constitutes a modification and to reduce diversity in practice in applying Topic 718. In order for a change to a share-based arrangement to not require Topic 718 modification accounting treatment, all of the following must be met: no change in fair value, no change in vesting conditions and no change in the balance sheet classification of the modified award. The ASU is effective for fiscal years beginning after December 15, 2017, including interim periods within those periods. Early adoption is permitted, including adoption in an interim period. The amendments should be applied prospectively to an award modified on or after the adoption date. We adopted the requirements of this ASU effective January 1, 2018, which did not impact our financial condition, results of operation, or related financial statement disclosures in the first quarter of 2018. In February 2018, the FASB issued ASU No. 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income . This amendment helps organizations address certain stranded income tax effects in accumulated other comprehensive income (AOCI) resulting from the enactment of the Tax Cuts and Jobs Act of 2017. The ASU requires financial statement preparers to disclose a description of the accounting policy for releasing income tax effects from AOCI, whether or not they elect to reclassify the stranded income tax effects from the Tax Cuts and Jobs Act of 2017, and information about the other income tax effects that are reclassified. The amendments are effective for all organizations for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The amendments in this ASU should be applied in either the period of adoption or retrospectively to each period (or periods) in which the effect of the change in the U.S. federal corporate tax rate in the Tax Cuts and Jobs Act of 2017 is recognized. We early adopted this ASU in the first quarter of 2018. See Note 7, Stockholders' Equity. Accounting Standards Not Yet Effective In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) . The amendments in this ASU intend to increase transparency and comparability among organizations by recognizing an asset, which represents the right to use the asset for the lease term, and a lease liability, which is a lessee's obligation to make lease payments measured on a discounted basis. This ASU generally applies to leasing arrangements exceeding a twelve month term. ASU 2016-02 is effective for annual periods, including interim periods within those annual periods beginning after December 15, 2018 and requires a modified retrospective method of adoption. Early application of the amendments is permitted. We intend to adopt this ASU during the first quarter of 2019, as required. We are continuing to evaluate our lease agreements and potential accounting software solutions as they become available. As of March 31, 2018, our undiscounted operating lease obligations that were off-balance sheet totaled $17.7 million (See Note 8, Commitments and Contingencies). Upon adoption of this ASU, the present values of leases currently classified as operating leases will be recognized as lease assets and liabilities on our consolidated balance sheets. Additional disclosures of key information about our leasing arrangements will also be required. We do not expect that the ASU will have a material impact on our capital ratios or return on average assets when adopted and we are currently evaluating the effect that the ASU will have on other components of our financial condition and results of operations. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . Under the new guidance, entities will be required to measure expected credit losses by utilizing forward-looking information to assess an entity's allowance for credit losses. The measurement of expected credit losses will be based on historical experience, current conditions and reasonable and supportable forecasts that affect the collectability of a credit over its remaining life. In addition, the ASU amends the accounting for potential credit losses on available-for-sale debt securities and purchased financial assets with credit deterioration. ASU 2016-13 is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. We have formed an internal Current Expected Credit Loss ("CECL") committee and are working with our third party vendor to determine the appropriate methodologies and resources to utilize in preparation for transition to the new accounting standards. In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities . This amendment changes both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. It is intended to more closely align hedge accounting with companies' risk management strategies, simplify the application of hedge accounting, and increase transparency as to the scope and results of hedging programs. The ASU is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. The amended presentation and disclosure guidance will be required prospectively. We expect this amendment to affect the presentation of our hedging activities, but we do not expect it to have a material impact on our financial condition or results of operations.

Fair Value of Assets and Liabil

Fair Value of Assets and Liabilities	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value of Assets and Liabilities	Fair Value of Assets and Liabilities Fair Value Hierarchy and Fair Value Measurement We group our assets and liabilities that are measured at fair value in three levels within the fair value hierarchy, based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. These levels are: Level 1: Valuations are based on unadjusted quoted prices in active markets for identical assets or liabilities. Level 2: Valuations are based on quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active and model-based valuations for which all significant assumptions are observable or can be corroborated by observable market data. Level 3: Valuations are based on unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Values are determined using pricing models and discounted cash flow models and may include significant Management judgment and estimation. Transfers between levels of the fair value hierarchy are recognized through our monthly and/or quarterly valuation process in the reporting period during which the event or circumstances that caused the transfer occurred. The following table summarizes our assets and liabilities that were required to be recorded at fair value on a recurring basis. (in thousands) Description of Financial Instruments Carrying Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Measurement Categories: Changes in Fair Value Recorded In 1 March 31, 2018 Securities available-for-sale: Mortgage-backed securities and collateralized mortgage obligations issued by U.S. government agencies $ 262,666 $ — $ 262,666 $ — OCI SBA-backed securities 33,538 — 33,373 165 OCI Debentures of government sponsored agencies 27,336 — 27,336 — OCI Privately-issued collateralized mortgage obligations 1,390 — 1,390 — OCI Obligations of state and political subdivisions 93,414 — 93,414 — OCI Corporate bonds 5,538 — 5,538 — OCI Derivative financial assets (interest rate contracts) 239 — 239 — NI Derivative financial liabilities (interest rate contracts) 376 — 376 — NI December 31, 2017 Securities available-for-sale: Mortgage-backed securities and collateralized mortgage obligations issued by U.S. government agencies $ 188,061 $ — $ 188,061 $ — OCI SBA-backed securities 25,982 25,817 165 OCI Debentures of government sponsored agencies 12,938 — 12,938 — OCI Privately-issued collateralized mortgage obligations 1,431 — 1,431 — OCI Obligations of state and political subdivisions 97,491 — 97,491 — OCI Corporate bonds 6,564 — 6,564 — OCI Derivative financial assets (interest rate contracts) 74 — 74 — NI Derivative financial liabilities (interest rate contracts) 740 — 740 — NI 1 Other comprehensive income ("OCI") or net income ("NI"). Securities available-for-sale are recorded at fair value on a recurring basis. When available, quoted market prices (Level 1) are used to determine the fair value of securities available-for-sale. If quoted market prices are not available, we obtain pricing information from a reputable third-party service provider, who may utilize valuation techniques that use current market-based or independently sourced parameters, such as bid/ask prices, dealer-quoted prices, interest rates, benchmark yield curves, prepayment speeds, probability of default, loss severity and credit spreads (Level 2). Level 2 securities include obligations of state and political subdivisions, U.S. agencies or government-sponsored agencies' debt securities, mortgage-backed securities, government agency-issued, privately-issued collateralized mortgage obligations, and corporate bonds. As of March 31, 2018 and December 31, 2017 , there were no securities that were considered Level 1 securities. As of March 31, 2018 , we had one available-for-sale security that was considered a Level 3 security. The security is a U.S. government agency obligation collateralized by a small number of business equipment loans guaranteed by the Small Business Administration ("SBA") program. The security is not actively traded and is owned only by a few investors. The significant unobservable data that is reflected in the fair value measurement include dealer quotes, projected prepayment speeds/average life and credit information, among other things. The unrealized loss on this SBA-guaranteed security recorded as part of other comprehensive income remained at $2 thousand at both March 31, 2018 and December 31, 2017. Securities held-to-maturity may be written down to fair value (determined using the same techniques discussed above for securities available-for-sale) as a result of other-than-temporary impairment, and we did not record any write-downs during the quarter ended March 31, 2018 or year ended December 31, 2017. On a recurring basis, derivative financial instruments are recorded at fair value, which is based on the income approach using observable Level 2 market inputs, reflecting market expectations of future interest rates as of the measurement date. Standard valuation techniques are used to calculate the present value of the future expected cash flows assuming an orderly transaction. Valuation adjustments may be made to reflect both our own credit risk and the counterparties’ credit risk in determining the fair value of the derivatives. Level 2 inputs for the valuations are limited to observable market prices for London Interbank Offered Rate ("LIBOR") and Overnight Index Swap ("OIS") rates (for the very short term), quoted prices for LIBOR futures contracts, observable market prices for LIBOR and OIS swap rates, and one-month and three-month LIBOR basis spreads at commonly quoted intervals. Mid-market pricing of the inputs is used as a practical expedient in the fair value measurements. We project spot rates at reset days specified by each swap contract to determine future cash flows, then discount to present value using either LIBOR or OIS curves depending on whether the swap positions are fully collateralized as of the measurement date. When the value of any collateral placed with counterparties is less than the interest rate derivative liability, a credit valuation adjustment ("CVA") is applied to reflect the credit risk we pose to counterparties. We have used the spread between the Standard & Poor's BBB rated U.S. Bank Composite rate and LIBOR for the closest maturity term corresponding to the duration of the swaps to derive the CVA. A similar credit risk adjustment, correlated to the credit standing of the counterparty, is made when collateral posted by the counterparty does not fully cover their liability to the Bank. For further discussion on our methodology in valuing our derivative financial instruments, refer to Note 9, Derivative Financial Instruments and Hedging Activities. Certain financial assets may be measured at fair value on a non-recurring basis. These assets are subject to fair value adjustments that result from the application of the lower of cost or fair value accounting or write-downs of individual assets, such as impaired loans that are collateral dependent and other real estate owned ("OREO"). As of March 31, 2018 and December 31, 2017, we do not carry any assets measured at fair value on a non-recurring basis. Disclosures about Fair Value of Financial Instruments The following table summarizes fair value estimates for financial instruments as of March 31, 2018 and December 31, 2017 , excluding financial instruments recorded at fair value on a recurring basis (summarized in the first table in this note). The carrying amounts in the following table are recorded in the consolidated statements of condition under the indicated captions. Further, we have not disclosed the fair value of financial instruments specifically excluded from disclosure requirements such as bank-owned life insurance policies ("BOLI") and non-maturity deposit liabilities. Additionally, we hold shares of FHLB stock and Visa Inc. Class B common stock at cost. These shares are restricted from resale, except among member banks, and their values are discussed in Note 4, Investment Securities . March 31, 2018 December 31, 2017 (in thousands) Carrying Amounts Fair Value Fair Value Hierarchy Carrying Amounts Fair Value Fair Value Hierarchy Financial assets (recorded at amortized cost) Cash and cash equivalents $ 159,347 $ 159,347 Level 1 $ 203,545 $ 203,545 Level 1 Investment securities held-to-maturity 149,013 145,818 Level 2 151,032 151,032 Level 2 Loans, net 1,655,969 1,622,552 Level 3 1,663,246 1,650,198 Level 3 Interest receivable 7,087 7,087 Level 2 7,501 7,501 Level 2 Financial liabilities (recorded at amortized cost) Time deposits 145,942 145,212 Level 2 160,116 159,540 Level 2 Subordinated debentures 5,772 6,820 Level 3 5,739 5,118 Level 3 Interest payable 172 172 Level 2 191 191 Level 2 Commitments - The value of unrecognized financial instruments is estimated based on the fee income associated with the commitments which, in the absence of credit exposure, is considered to approximate their settlement value. The fair value of commitment fees was not material at March 31, 2018 and December 31, 2017 .

Investment Securities

Investment Securities	3 Months Ended
	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Investment Securities	Investment Securities Our investment securities portfolio consists of obligations of state and political subdivisions, corporate bonds, U.S. government agency securities, including residential and commercial mortgage-backed securities (“MBS”) and collateralized mortgage obligations (“CMOs”) issued or guaranteed by Federal National Mortgage Association ("FNMA"), Federal Home Loan Mortgage Corporation ("FHLMC"), or Government National Mortgage Association ("GNMA"), debentures issued by government-sponsored agencies such as FNMA, Federal Farm Credit Bureau, FHLB and FHLMC, as well as privately issued CMOs, as reflected in the following table: March 31, 2018 December 31, 2017 Amortized Fair Gross Unrealized Amortized Fair Gross Unrealized (in thousands) Cost Value Gains (Losses) Cost Value Gains (Losses) Held-to-maturity: Obligations of state and political subdivisions $ 19,599 $ 19,857 $ 278 $ (20 ) $ 19,646 $ 19,998 $ 383 $ (31 ) MBS pass-through securities issued by FHLMC and FNMA 97,222 94,735 12 (2,499 ) 100,376 100,096 234 (514 ) CMOs issued by FHLMC 32,192 31,226 1 (967 ) 31,010 30,938 2 (74 ) Total held-to-maturity 149,013 145,818 291 (3,486 ) 151,032 151,032 619 (619 ) Available-for-sale: Securities of U.S. government agencies: MBS pass-through securities issued by FHLMC and FNMA 93,915 92,029 22 (1,908 ) 65,559 65,262 126 (423 ) SBA-backed securities 33,809 33,538 8 (279 ) 25,979 25,982 58 (55 ) CMOs issued by FNMA 34,210 33,613 9 (606 ) 35,340 35,125 33 (248 ) CMOs issued by FHLMC 123,007 120,374 60 (2,693 ) 70,514 69,889 3 (628 ) CMOs issued by GNMA 17,173 16,650 5 (528 ) 17,953 17,785 26 (194 ) Debentures of government- sponsored agencies 27,446 27,336 6 (116 ) 12,940 12,938 3 (5 ) Privately issued CMOs 1,389 1,390 3 (2 ) 1,432 1,431 1 (2 ) Obligations of state and political subdivisions 95,395 93,414 99 (2,080 ) 98,027 97,491 298 (834 ) Corporate bonds 5,527 5,538 27 (16 ) 6,541 6,564 26 (3 ) Total available-for-sale 431,871 423,882 239 (8,228 ) 334,285 332,467 574 (2,392 ) Total investment securities $ 580,884 $ 569,700 $ 530 $ (11,714 ) $ 485,317 $ 483,499 $ 1,193 $ (3,011 ) The amortized cost and fair value of investment debt securities by contractual maturity at March 31, 2018 are shown in the following table. Expected maturities may differ from contractual maturities if the issuers of the securities have the right to call or prepay obligations with or without call or prepayment penalties. March 31, 2018 December 31, 2017 Held-to-Maturity Available-for-Sale Held-to-Maturity Available-for-Sale (in thousands) Amortized Cost Fair Value Amortized Cost Fair Value Amortized Cost Fair Value Amortized Cost Fair Value Within one year $ 3,230 $ 3,256 $ 10,291 $ 10,281 $ 2,151 $ 2,172 $ 10,268 $ 10,272 After one but within five years 14,458 14,599 77,606 76,619 15,577 15,791 71,576 71,237 After five years through ten years 53,048 51,589 225,526 220,904 54,641 54,554 129,723 128,954 After ten years 78,277 76,374 118,448 116,078 78,663 78,515 122,718 122,004 Total $ 149,013 $ 145,818 $ 431,871 $ 423,882 $ 151,032 $ 151,032 $ 334,285 $ 332,467 Pledged investment securities are shown in the following table: (in thousands) March 31, 2018 December 31, 2017 Pledged to the State of California: Secure public deposits in compliance with the Local Agency Security Program $ 102,738 $ 107,829 Collateral for trust deposits 754 761 Total investment securities pledged to the State of California $ 103,492 $ 108,590 Collateral for Wealth Management and Trust Services ("WMTS") checking account $ 2,018 $ 2,026 As part of our ongoing review of our investment securities portfolio, we reassessed the classification of certain MBS pass-through and CMOs securities issued by FHLMC and FNMA. During 2017, we transferred $129 million of these securities, which we intend and have the ability to hold to maturity, from available-for-sale securities to held-to-maturity at fair value. The net unrealized pre-tax loss of $3.0 million at the date of transfer remained in accumulated other comprehensive income and are amortized over the remaining lives of the securities. Amortization of the net unrealized pre-tax losses totaled $136 thousand and $41 thousand in the first quarter of 2018 and 2017, respectively. Other-Than-Temporarily Impaired ("OTTI") Debt Securities We have evaluated the credit of our investment securities and their issuers and/or insurers. Based on our evaluation, Management has determined that no investment security in our investment portfolio is other-than-temporarily impaired as of March 31, 2018 . We do not have the intent and it is more likely than not that we will not have to sell the remaining securities temporarily impaired at March 31, 2018 before recovery of the amortized cost basis. There were 258 and 198 investment securities in unrealized loss positions at March 31, 2018 and December 31, 2017 , respectively. Those securities are summarized and classified according to the duration of the loss period in the following tables: March 31, 2018 < 12 continuous months ≥ 12 continuous months Total securities in a loss position (in thousands) Fair value Unrealized loss Fair value Unrealized loss Fair value Unrealized loss Held-to-maturity: Obligations of state and political subdivisions $ 3,636 $ (20 ) $ — $ — $ 3,636 $ (20 ) MBS pass-through securities issued by FHLMC and FNMA 22,570 (611 ) 69,808 (1,888 ) 92,378 (2,499 ) CMOs issued by FHLMC 16,571 (445 ) 12,667 (522 ) 29,238 (967 ) Total held-to-maturity 42,777 (1,076 ) 82,475 (2,410 ) 125,252 (3,486 ) Available-for-sale: MBS pass-through securities issued by FHLMC and FNMA 71,449 (1,314 ) 18,895 (594 ) 90,344 (1,908 ) SBA-backed securities 24,816 (277 ) 165 (2 ) 24,981 (279 ) CMOs issued by FNMA 28,289 (473 ) 5,061 (133 ) 33,350 (606 ) CMOs issued by FHLMC 107,801 (2,693 ) — — 107,801 (2,693 ) CMOs issued by GNMA 15,955 (528 ) — — 15,955 (528 ) Debentures of government- sponsored agencies 12,330 (116 ) — — 12,330 (116 ) Privately issued CMOs 862 (2 ) — — 862 (2 ) Obligations of state and political subdivisions 63,831 (920 ) 18,880 (1,160 ) 82,711 (2,080 ) Corporate bonds 4,032 (16 ) — — 4,032 (16 ) Total available-for-sale 329,365 (6,339 ) 43,001 (1,889 ) 372,366 (8,228 ) Total temporarily impaired securities $ 372,142 $ (7,415 ) $ 125,476 $ (4,299 ) $ 497,618 $ (11,714 ) December 31, 2017 < 12 continuous months ≥ 12 continuous months Total securities in a loss position (in thousands) Fair value Unrealized loss Fair value Unrealized loss Fair value Unrealized loss Held-to-maturity: Obligations of state and political subdivisions $ 3,648 $ (31 ) $ — $ — $ 3,648 $ (31 ) MBS pass-through securities issued by FHLMC and FNMA $ 16,337 $ (143 ) $ 46,845 $ (371 ) $ 63,182 $ (514 ) CMOs issued by FHLMC 11,066 (31 ) 13,824 (43 ) 24,890 (74 ) Total held-to-maturity 31,051 (205 ) 60,669 (414 ) 91,720 (619 ) Available-for-sale: MBS pass-through securities issued by FHLMC and FNMA 32,189 (121 ) 15,325 (302 ) 47,514 (423 ) SBA-backed securities 11,028 (53 ) 165 (2 ) 11,193 (55 ) CMOs issued by FNMA 26,401 (171 ) 5,440 (77 ) 31,841 (248 ) CMOs issued by FHLMC 69,276 (628 ) — — 69,276 (628 ) CMOs issued by GNMA 14,230 (194 ) — — 14,230 (194 ) Debentures of government- sponsored agencies 2,984 (5 ) — — 2,984 (5 ) Privately issued CMO's 1,310 (2 ) — — 1,310 (2 ) Obligations of state and political subdivisions 52,197 (288 ) 19,548 (546 ) 71,745 (834 ) Corporate bonds 3,060 (3 ) — — 3,060 (3 ) Total available-for-sale 212,675 (1,465 ) 40,478 (927 ) 253,153 (2,392 ) Total temporarily impaired securities $ 243,726 $ (1,670 ) $ 101,147 $ (1,341 ) $ 344,873 $ (3,011 ) As of March 31, 2018 , sixty-one investment securities in our portfolio had been in a continuous loss position for twelve months or more. They consisted of one SBA-backed security, four CMOs issued by FHLMC, three CMOs issued by FNMA, twenty-one agency MBS securities and thirty-two obligations of U.S. state and political subdivisions securities. We have evaluated the securities and believe that the decline in fair value is primarily driven by factors other than credit. It is probable that we will be able to collect all amounts due according to the contractual terms and no other-than-temporary impairment exists on these securities. The debenture of government-sponsored agency security is supported by the U.S. Federal Government, which protects us from credit losses. Based upon our assessment of the credit fundamentals, we concluded that these securities were not other-than-temporarily impaired at March 31, 2018 . There were one hundred ninety-seven investment securities in our portfolio that had been in temporary loss positions for less than twelve months as of March 31, 2018 , and their temporary loss positions mainly arose from changes in interest rates since purchase. They consisted of seven SBA-backed securities, five debentures of a U.S. government-sponsored agency, one hundred one obligations of U.S. state and political subdivisions, thirty-four MBS securities, forty-three CMOs issued by government-sponsored agencies, one privately issued CMO and six corporate bonds. Securities of government-sponsored agencies are supported by the U.S. Federal Government, which protects us from credit losses. Other temporarily impaired securities are deemed creditworthy after internal analysis of the issuers' latest financial information and credit enhancement. Additionally, all are rated as investment grade by at least one major rating agency. As a result of this impairment analysis, we concluded that these securities were not other-than-temporarily impaired at March 31, 2018 . Non-Marketable Securities As a member of the FHLB, we are required to maintain a minimum investment in FHLB capital stock determined by the Board of Directors of the FHLB. The minimum investment requirements can increase in the event we increase our total asset size or borrowings with the FHLB. Shares cannot be purchased or sold except between the FHLB and its members at the $100 per share par value. We held $11.1 million of FHLB stock recorded at cost in other assets on the consolidated statements of condition at both March 31, 2018 and December 31, 2017 . The carrying amounts of these investments are reasonable estimates of fair value because the securities are restricted to member banks and they do not have a readily determinable market value. Management does not believe that the FHLB stock is other-than-temporarily-impaired, due to FHLB's current financial condition. On April 26, 2018, FHLB announced a cash dividend to be distributed in mid-May 2018 at an annualized dividend rate of 7.00% . Cash dividends paid on FHLB capital stock are recorded as non-interest income. As a member bank of Visa U.S.A., we hold 16,939 shares of Visa Inc. Class B common stock with a carrying value of zero , which is equal to our cost basis. These shares are restricted from resale until their conversion into Class A (voting) shares upon the termination of Visa Inc.'s Covered Litigation escrow account. As a result of the restriction, these shares are not considered available-for-sale and are not carried at fair value. When converting this Class B common stock to Class A common stock based on the conversion rate of 1.6483 and the closing stock price of Class A shares, the value of our shares of Class B common stock would have been $3.3 million and $3.2 million at March 31, 2018 and December 31, 2017 , respectively. The conversion rate is subject to further reduction upon the final settlement of the covered litigation against Visa Inc. and its member banks. As such, the fair value of these Class B shares can differ significantly from their if-converted values. For further information, see Note 8, Commitments and Contingencies . We invest in low-income housing tax credit funds as a limited partner, which totaled $5.0 million and $2.1 million recorded in other assets as of March 31, 2018 and December 31, 2017 , respectively. In the first three months of 2018, we recognized $110 thousand of low-income housing tax credits and other tax benefits, net of $94 thousand of amortization expense of low-income housing tax credit investment, as a component of income tax expense. As of March 31, 2018 , our unfunded commitments for these low-income housing tax credit funds totaled $3.2 million . We did not recognize any impairment losses on these low-income housing tax credit investments during the first three months of 2018 or 2017, as the value of the future tax benefits exceeds the carrying value of the investments.

Loans and Allowance for Loan Lo

Loans and Allowance for Loan Losses	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Loans and Allowance for Loan Losses	Loans and Allowance for Loan Losses Credit Quality of Loans The following table shows outstanding loans by class and payment aging as of March 31, 2018 and December 31, 2017 . Loan Aging Analysis by Loan Class (in thousands) Commercial and industrial Commercial real estate, owner-occupied Commercial real estate, investor Construction Home equity Other residential 1 Installment and other consumer Total March 31, 2018 30-59 days past due $ — $ — $ — $ — $ 385 $ — $ — $ 385 60-89 days past due 4 — — — — — — 4 90 days or more past due — — — — — — — — Total past due 4 — — — 385 — — 389 Current 231,676 300,377 828,945 64,978 124,314 95,621 25,440 1,671,351 Total loans 3 $ 231,680 $ 300,377 $ 828,945 $ 64,978 $ 124,699 $ 95,621 $ 25,440 $ 1,671,740 Non-accrual loans 2 $ — $ — $ — $ — $ 392 $ — $ — $ 392 December 31, 2017 30-59 days past due $ — $ — $ — $ — $ 99 $ 255 $ 330 $ 684 60-89 days past due 1,340 — — — — — — 1,340 90 days or more past due — — — — 307 — — 307 Total past due 1,340 — — — 406 255 330 2,331 Current 234,495 300,963 822,984 63,828 132,061 95,271 27,080 1,676,682 Total loans 3 $ 235,835 $ 300,963 $ 822,984 $ 63,828 $ 132,467 $ 95,526 $ 27,410 $ 1,679,013 Non-accrual loans 2 $ — $ — $ — $ — $ 406 $ — $ — $ 406 1 Our residential loan portfolio does not include sub-prime loans, nor is it our practice to underwrite loans commonly referred to as "Alt-A mortgages", the characteristics of which are loans lacking full documentation, borrowers having low FICO scores or higher loan-to-value ratios. 2 One purchased credit impaired ("PCI") loan with an unpaid balance of $11 thousand and no carrying value was not accreting interest at March 31, 2018 . Three PCI loans with unpaid balances totaling $131 thousand and no carrying values were not accreting interest at December 31, 2017 . Amounts exclude accreting PCI loans totaling $2.1 million at both March 31, 2018 and December 31, 2017 as we have a reasonable expectation about future cash flows to be collected and we continue to recognize accretable yield on these loans in interest income. There were no accruing loans past due more than ninety days at March 31, 2018 or December 31, 2017 . 3 Amounts include net deferred loan origination costs of $928 thousand and $818 thousand at March 31, 2018 and December 31, 2017 , respectively. Amounts are also net of unaccreted purchase discounts on non-PCI loans of $1.1 million and $1.2 million at March 31, 2018 and December 31, 2017 , respectively. We generally make commercial loans to established small and mid-sized businesses to provide financing for their growth and working capital needs, equipment purchases and acquisitions. Management examines historical, current, and projected cash flows to determine the ability of the borrower to repay obligations as agreed. Commercial loans are made based primarily on the identified cash flows of the borrower and secondarily on the underlying collateral and guarantor support. The cash flows of borrowers, however, may not occur as expected, and the collateral securing these loans may fluctuate in value. Most commercial and industrial loans are secured by the assets being financed, such as accounts receivable and inventory, and typically include a personal guarantee. We target stable businesses with guarantors who provide additional sources of repayment and have proven to be resilient in periods of economic stress. Commercial real estate loans are subject to underwriting standards and processes similar to commercial loans discussed above. We underwrite these loans to be repaid from cash flow and to be supported by real property collateral. Underwriting standards for commercial real estate loans include, but are not limited to, debt coverage and loan-to-value ratios. Furthermore, the owners of the properties guarantee substantially all of our commercial real estate loans. Conditions in the real estate markets or in the general economy may adversely affect our commercial real estate loans. In the event of a vacancy, we expect guarantors to carry the loans until they find a replacement tenant. The owner's substantial equity investment provides a strong economic incentive to continue to support the commercial real estate projects. As such, we have generally experienced a relatively low level of loss and delinquencies in this portfolio. We generally make construction loans to developers and builders to finance construction, renovation and occasionally land acquisitions in anticipation of near-term development. These loans are underwritten after evaluation of the borrower's financial strength, reputation, prior track record, and independent appraisals. Significant events can affect the construction industry, including: the inherent volatility of real estate markets and vulnerability to delays due to weather, change orders, inability to obtain construction permits, labor or material shortages, and price changes. Estimates of construction costs and value associated with the completed project may be inaccurate. Repayment of construction loans is largely dependent on the ultimate success of the project. Consumer loans primarily consist of home equity lines of credit, other residential loans and floating homes, along with a small number of installment loans. Our other residential loans include tenancy-in-common fractional interest loans ("TIC") located almost entirely in San Francisco County. We originate consumer loans utilizing credit score information, debt-to-income ratio and loan-to-value ratio analysis. Diversification among consumer loan types, coupled with relatively small loan amounts that are spread across many individual borrowers, mitigates risk. We use a risk rating system to evaluate asset quality, and to identify and monitor credit risk in individual loans, and in the loan portfolio. Our definitions of “Special Mention” risk graded loans, or worse, are consistent with those used by the Federal Deposit Insurance Corporation ("FDIC"). Our internally assigned grades are as follows: Pass and Watch : Loans to borrowers of acceptable or better credit quality. Borrowers in this category demonstrate fundamentally sound financial positions, repayment capacity, credit history and management expertise. Loans in this category must have an identifiable and stable source of repayment and meet the Bank’s policy regarding debt-service-coverage ratios. These borrowers are capable of sustaining normal economic, market or operational setbacks without significant financial consequences. Negative external industry factors are generally not present. The loan may be secured, unsecured or supported by non-real estate collateral for which the value is more difficult to determine and/or marketability is more uncertain. This category also includes “Watch” loans, where the primary source of repayment has been delayed. “Watch” is intended to be a transitional grade, with either an upgrade or downgrade within a reasonable period. Special Mention : Potential weaknesses that deserve close attention. If left uncorrected, those potential weaknesses may result in deterioration of the payment prospects for the asset. Special Mention assets do not present sufficient risk to warrant adverse classification. Substandard : Inadequately protected by either the current sound worth and paying capacity of the obligor or the collateral pledged, if any. A Substandard asset has a well-defined weakness or weaknesses that jeopardize(s) the liquidation of the debt. Substandard assets are characterized by the distinct possibility that we will sustain some loss if such weaknesses or deficiencies are not corrected. Well-defined weaknesses include adverse trends or developments of the borrower’s financial condition, managerial weaknesses and/or significant collateral deficiencies. Doubtful : Critical weaknesses that make collection or liquidation in full improbable. There may be specific pending events that work to strengthen the asset; however, the amount or timing of the loss may not be determinable. Pending events generally occur within one year of the asset being classified as Doubtful. Examples include: merger, acquisition, or liquidation; capital injection; guarantee; perfecting liens on additional collateral; and refinancing. Such loans are placed on non-accrual status and usually are collateral-dependent. We regularly review our credits for accuracy of risk grades whenever we receive new information. Borrowers are required to submit financial information at regular intervals. Generally, commercial borrowers with lines of credit are required to submit financial information with reporting intervals ranging from monthly to annually depending on credit size, risk and complexity. Investor commercial real estate borrowers are generally required to submit rent rolls or property income statements annually. We monitor construction loans monthly and review them on an ongoing basis. We review home equity and other consumer loans based on delinquency status. We also review loans graded “Watch” or worse, regardless of loan type, no less than quarterly. The following table represents an analysis of the carrying amount in loans, net of deferred fees and costs and purchase premiums or discounts, by internally assigned risk grades, including PCI loans, at March 31, 2018 and December 31, 2017 . Credit Risk Profile by Internally Assigned Risk Grade (in thousands) Commercial and industrial Commercial real estate, owner-occupied Commercial real estate, investor Construction Home equity Other residential Installment and other consumer Purchased credit-impaired Total March 31, 2018 Pass $ 213,676 $ 279,899 $ 824,867 $ 62,003 $ 122,760 $ 95,621 $ 25,339 $ 1,338 $ 1,625,503 Special Mention 4,761 9,918 2,954 — — — — 797 18,430 Substandard 13,191 9,366 327 2,975 1,847 — 101 — 27,807 Total loans $ 231,628 $ 299,183 $ 828,148 $ 64,978 $ 124,607 $ 95,621 $ 25,440 $ 2,135 $ 1,671,740 December 31, 2017 Pass $ 214,636 $ 281,104 $ 818,570 $ 60,859 $ 130,558 $ 95,526 $ 27,287 $ 1,325 $ 1,629,865 Special Mention 9,318 9,284 1,850 — — — — 790 21,242 Substandard 11,816 9,409 1,774 2,969 1,815 — 123 — 27,906 Total loans $ 235,770 $ 299,797 $ 822,194 $ 63,828 $ 132,373 $ 95,526 $ 27,410 $ 2,115 $ 1,679,013 Troubled Debt Restructuring Our loan portfolio includes certain loans modified in a troubled debt restructuring (“TDR”), where we have granted economic concessions to borrowers experiencing financial difficulties. These concessions typically result from our loss mitigation activities and could include reductions in the interest rate, payment extensions, forgiveness of principal, forbearance or other actions. TDRs on non-accrual status at the time of restructure may be returned to accruing status after Management considers the borrower’s sustained repayment performance for a reasonable period, generally six months, and obtains reasonable assurance of repayment and performance. We may remove a loan from TDR designation if it meets all of the following conditions: • The loan is subsequently refinanced or restructured at current market interest rates and the new terms are consistent with the treatment of creditworthy borrowers under regular underwriting standards; • The borrower is no longer considered to be in financial difficulty; • Performance on the loan is reasonably assured; and; • Existing loan did not have any forgiveness of principal or interest. The same Management level that approved the upgrading of the loan classification must approve the removal of TDR status. During the three months ended March 31, 2018, one TIC loan with a recorded investment of $150 thousand was removed from TDR designation after meeting all of the conditions noted above. There were no loans removed from TDR designation during 2017. The following table summarizes the carrying amount of TDR loans by loan class as of March 31, 2018 and December 31, 2017 . (in thousands) Recorded investment in Troubled Debt Restructurings 1 March 31, 2018 December 31, 2017 Commercial and industrial $ 2,267 $ 2,165 Commercial real estate, owner-occupied 7,007 6,999 Commercial real estate, investor 1,854 2,171 Construction 2,976 2,969 Home equity 347 347 Other residential 992 1,148 Installment and other consumer 712 721 Total $ 16,155 $ 16,520 1 There were no TDR loans on non-accrual status at March 31, 2018 and December 31, 2017 . The following table presents information for loans modified in a TDR during the presented periods, including the number of modified contracts, the recorded investment in the loans prior to modification, and the recorded investment in the loans at period end after being restructured. The following table excludes fully charged-off TDR loans and loans modified in a TDR and subsequently paid-off during the years presented. (dollars in thousands) Number of Contracts Modified Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment at Period End Troubled Debt Restructurings during the three months ended March 31, 2018: None — $ — $ — $ — Troubled Debt Restructurings during the three months ended March 31, 2017: Installment and other consumer 1 $ 50 $ 50 $ 50 The modification during the three months ended March 31, 2017 primarily involved an interest rate concession and other changes to loan terms. During the first three months of 2018 and 2017, there were no defaults on loans that had been modified in a TDR within the prior twelve-month period. We report defaulted TDRs based on a payment default definition of more than ninety days past due. Impaired Loans The following tables summarize information by class on impaired loans and their related allowances. Total impaired loans include non-accrual loans, accruing TDR loans and accreting PCI loans that have experienced post-acquisition declines in cash flows expected to be collected. (in thousands) Commercial and industrial Commercial real estate, owner-occupied Commercial real estate, investor Construction Home equity Other residential Installment and other consumer Total March 31, 2018 Recorded investment in impaired loans: With no specific allowance recorded $ 307 $ — $ — $ 2,692 $ 392 $ 992 $ 46 $ 4,429 With a specific allowance recorded 1,960 7,007 1,854 284 347 — 666 12,118 Total recorded investment in impaired loans $ 2,267 $ 7,007 $ 1,854 $ 2,976 $ 739 $ 992 $ 712 $ 16,547 Unpaid principal balance of impaired loans $ 2,260 $ 6,993 $ 1,847 $ 2,962 $ 736 $ 991 $ 711 $ 16,500 Specific allowance 35 162 48 11 6 — 92 354 Average recorded investment in impaired loans during the quarter ended 2,216 7,003 2,012 2,972 746 1,070 717 16,736 Interest income recognized on impaired loans during the quarter ended 1 155 66 22 38 5 13 7 306 Average recorded investment in impaired loans during the quarter ended 2,138 6,997 2,783 3,243 713 1,571 939 18,384 Interest income recognized on impaired loans during the quarter ended 1 23 66 23 34 8 19 10 183 1 Interest income recognized on a cash basis totaled $128 thousand in the first quarter of 2018 and was related to the pay-off of two non-accrual commercial PCI loans. No interest income on impaired loans was recognized on a cash basis during the three months ended March 31, 2017. (in thousands) Commercial and industrial Commercial real estate, owner-occupied Commercial real estate, investor Construction Home equity Other residential Installment and other consumer Total December 31, 2017 Recorded investment in impaired loans: With no specific allowance recorded $ 309 $ — $ — $ 2,689 $ 406 $ 995 $ 46 $ 4,445 With a specific allowance recorded 1,856 6,999 2,171 280 347 153 675 12,481 Total recorded investment in impaired loans $ 2,165 $ 6,999 $ 2,171 $ 2,969 $ 753 $ 1,148 $ 721 $ 16,926 Unpaid principal balance of impaired loans $ 2,278 $ 6,993 $ 2,168 $ 2,963 $ 750 $ 1,147 $ 720 $ 17,019 Specific allowance $ 50 $ 188 $ 159 $ 7 $ 6 $ 1 $ 102 $ 513 Management monitors delinquent loans continuously and identifies problem loans, generally loans graded Substandard or worse, loans on non-accrual status and loans modified in a TDR, to be evaluated individually for impairment. Generally, the recorded investment in impaired loans is net of any charge-offs from estimated losses related to specifically identified impaired loans when they are deemed uncollectible. There were no charged-off amounts on impaired loans at March 31, 2018 or December 31, 2017 . In addition, the recorded investment in impaired loans is net of purchase discounts or premiums on acquired loans and deferred fees and costs. At March 31, 2018 and December 31, 2017 , unused commitments to extend credit on impaired loans, including performing loans to borrowers whose terms have been modified in TDRs, totaled $610 thousand and $935 thousand , respectively. The following tables disclose activity in the allowance for loan losses ("ALLL") and the recorded investment in loans by class, as well as the related ALLL disaggregated by impairment evaluation method. Allowance for Loan Losses Rollforward for the Period (in thousands) Commercial and industrial Commercial real estate, owner-occupied Commercial real estate, investor Construction Home equity Other residential Installment and other consumer Unallocated Total Three months ended March 31, 2018 Beginning balance $ 3,654 $ 2,294 $ 6,475 $ 681 $ 1,031 $ 536 $ 378 $ 718 $ 15,767 Provision (reversal) 35 (214 ) (20 ) 16 (52 ) 7 (27 ) 255 — Charge-offs — — — — — — — — — Recoveries 4 — — — — — — — 4 Ending balance $ 3,693 $ 2,080 $ 6,455 $ 697 $ 979 $ 543 $ 351 $ 973 $ 15,771 Three months ended March 31, 2017 Beginning balance $ 3,248 $ 1,753 $ 6,320 $ 781 $ 973 $ 454 $ 372 $ 1,541 $ 15,442 Provision (reversal) 1,386 239 (187 ) (235 ) 17 (10 ) (11 ) (1,199 ) — Charge-offs (284 ) — — — — — (3 ) — (287 ) Recoveries 63 — — — — — 1 — 64 Ending balance $ 4,413 $ 1,992 $ 6,133 $ 546 $ 990 $ 444 $ 359 $ 342 $ 15,219 Allowance for Loan Losses and Recorded Investment in Loans (dollars in thousands) Commercial and industrial Commercial real estate, owner-occupied Commercial real estate, investor Construction Home equity Other residential Installment and other consumer Unallocated Total March 31, 2018 Ending ALLL related to loans collectively evaluated for impairment $ 3,658 $ 1,918 $ 6,407 $ 686 $ 973 $ 543 $ 259 $ 973 $ 15,417 Ending ALLL related to loans individually evaluated for impairment 35 162 48 11 6 — 92 — 354 Ending ALLL related to purchased credit-impaired loans — — — — — — — — — Ending balance $ 3,693 $ 2,080 $ 6,455 $ 697 $ 979 $ 543 $ 351 $ 973 $ 15,771 Recorded Investment: Collectively evaluated for impairment $ 229,361 $ 292,176 $ 826,294 $ 62,002 $ 123,868 $ 94,629 $ 24,728 $ — $ 1,653,058 Individually evaluated for impairment 2,267 7,007 1,854 2,976 739 992 712 — 16,547 Purchased credit-impaired 52 1,194 797 — 92 — — — 2,135 Total $ 231,680 $ 300,377 $ 828,945 $ 64,978 $ 124,699 $ 95,621 $ 25,440 $ — $ 1,671,740 Ratio of allowance for loan losses to total loans 1.59 % 0.69 % 0.78 % 1.07 % 0.79 % 0.57 % 1.38 % NM 0.94 % Allowance for loan losses to non-accrual loans NM NM NM NM 250 % NM NM NM 4,023 % NM - Not Meaningful Allowance for Loan Losses and Recorded Investment in Loans (dollars in thousands) Commercial and industrial Commercial real estate, owner-occupied Commercial real estate, investor Construction Home equity Other residential Installment and other consumer Unallocated Total December 31, 2017 Ending ALLL related to loans collectively evaluated for impairment $ 3,604 $ 2,106 $ 6,316 $ 674 $ 1,025 $ 535 $ 276 $ 718 $ 15,254 Ending ALLL related to loans individually evaluated for impairment 50 188 159 7 6 1 102 — 513 Ending ALLL related to purchased credit-impaired loans — — — — — — — — — Ending balance $ 3,654 $ 2,294 $ 6,475 $ 681 $ 1,031 $ 536 $ 378 $ 718 $ 15,767 Recorded Investment: Collectively evaluated for impairment $ 233,605 $ 292,798 $ 820,023 $ 60,859 $ 131,620 $ 94,378 $ 26,689 $ — $ 1,659,972 Individually evaluated for impairment 2,165 6,999 2,171 2,969 753 1,148 721 — 16,926 Purchased credit-impaired 65 1,166 790 — 94 — — — 2,115 Total $ 235,835 $ 300,963 $ 822,984 $ 63,828 $ 132,467 $ 95,526 $ 27,410 $ — $ 1,679,013 Ratio of allowance for loan losses to total loans 1.55 % 0.76 % 0.79 % 1.07 % 0.78 % 0.56 % 1.38 % NM 0.94 % Allowance for loan losses to non-accrual loans NM NM NM NM 254 % NM NM NM 3,883 % NM - Not Meaningful Purchased Credit-Impaired Loans Acquired loans are considered credit-impaired if there is evidence of significant deterioration of credit quality since origination and it is probable, at the acquisition date, that we will be unable to collect all contractually required payments receivable. Management has determined certain loans purchased in our three bank acquisitions to be PCI loans based on credit indicators such as nonaccrual status, past due status, loan risk grade, loan-to-value ratio, etc. Revolving credit agreements (e.g., home equity lines of credit and revolving commercial loans) are not considered PCI loans as cash flows cannot be reasonably estimated. The following table reflects the unpaid principal balance and related carrying value of PCI loans. PCI Loans March 31, 2018 December 31, 2017 (in thousands) Unpaid Principal Balance Carrying Value Unpaid Principal Balance Carrying Value Commercial and industrial $ 141 $ 52 $ 276 $ 65 Commercial real estate, owner occupied 1,284 1,194 1,297 1,166 Commercial real estate, investor 1,056 797 1,064 790 Home equity 226 92 231 94 Total purchased credit-impaired loans $ 2,707 $ 2,135 $ 2,868 $ 2,115 The activities in the accretable yield, or income expected to be earned over the remaining lives of the PCI loans were as follows: Accretable Yield Three months ended (in thousands) March 31, 2018 March 31, 2017 Balance at beginning of period $ 1,254 $ 1,476 Accretion (112 ) (90 ) Balance at end of period $ 1,142 $ 1,386 Pledged Loans Our FHLB line of credit is secured under terms of a blanket collateral agreement by a pledge of certain qualifying loans with unpaid principal balances of $1,007.5 million and $887.9 million at March 31, 2018 and December 31, 2017 , respectively. In addition, we pledge a certain residential loan portfolio, which totaled $65.8 million and $67.6 million at March 31, 2018 and December 31, 2017 , respectively, to secure our borrowing capacity with the Federal Reserve Bank ("FRB"). Also, see Note 6, Borrowings. Related Party Loans The Bank has, and expects to have in the future, banking transactions in the ordinary course of its business with directors, officers, principal shareholders and their businesses or associates. These transactions, including loans, are granted on substantially the same terms, including interest rates and collateral on loans, as those prevailing at the same time for comparable transactions with persons not related to us. Likewise, these transactions do not involve more than the normal risk of collectability or present other unfavorable features. Related party loans totaled $11.3 million at March 31, 2018 compared to $11.9 million at December 31, 2017 . In addition, undisbursed commitments to related parties totaled $8.8 million and $9.1 million at March 31, 2018 and December 31, 2017 , respectively.

Borrowings

Borrowings	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Borrowings	Borrowings Federal Funds Purchased – The Bank had unsecured lines of credit with correspondent banks for overnight borrowing totaling $100.4 million at March 31, 2018 and December 31, 2017 . In general, interest rates on these lines approximate the federal funds target rate. We had no overnight borrowings under these credit facilities at March 31, 2018 or December 31, 2017 . Federal Home Loan Bank Borrowings – As of March 31, 2018 and December 31, 2017 , the Bank had lines of credit with the FHLB totaling $617.0 million and $538.9 million , respectively, based on eligible collateral of certain loans. There were no FHLB overnight borrowings at March 31, 2018 or December 31, 2017 . Federal Reserve Line of Credit – The Bank has a line of credit with the FRBSF secured by certain residential loans. At March 31, 2018 and December 31, 2017 , the Bank had borrowing capacity under this line totaling $49.9 million and $52.1 million , respectively, and had no outstanding borrowings with the FRBSF. As part of an acquisition, Bancorp assumed two subordinated debentures due to NorCal Community Bancorp Trusts I and II (the "Trusts"), established for the sole purpose of issuing trust preferred securities on September 22, 2003 and December 29, 2005, respectively. The subordinated debentures were recorded at fair values totaling $4.95 million at acquisition date with contractual values totaling $8.2 million . The difference between the contractual balance and the fair value at acquisition date is accreted into interest expense over the lives of the debentures. Accretion on the subordinated debentures totaled $33 thousand and $42 thousand in the first three months of 2018 and 2017, respectively. Bancorp has the option to defer payment of the interest on the subordinated debentures for a period of up to five years, as long as there is no default on the subordinated debentures. In the event of interest deferral, dividends to Bancorp common stockholders are prohibited. The trust preferred securities were sold and issued in private transactions pursuant to an exemption from registration under the Securities Act of 1933, as amended. Bancorp has guaranteed, on a subordinated basis, distributions and other payments due on trust preferred securities totaling $8.0 million issued by the Trusts, which have identical maturity, repricing, and payment terms as the subordinated debentures. The following table summarizes the contractual terms of the subordinated debentures due to the Trusts as of March 31, 2018 : (in thousands) Subordinated debentures due to NorCal Community Bancorp Trust I on October 7, 2033 with interest payable quarterly, based on 3-month LIBOR plus 3.05%, repricing quarterly (4.77% as of March 31, 2018), redeemable, in whole or in part, on any interest payment date $ 4,124 Subordinated debentures due to NorCal Community Bancorp Trust II on March 15, 2036 with interest payable quarterly, based on 3-month LIBOR plus 1.40%, repricing quarterly (3.52% as of March 31, 2018), redeemable, in whole or in part, on any interest payment date 4,124 Total $ 8,248

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Stockholders' Equity	Stockholders' Equity Dividends The following table summarizes cash dividends paid to common shareholders, recorded as a reduction of retained earnings. Three months ended (in thousands, except per share data) March 31, 2018 March 31, 2017 Cash dividends to common stockholders $ 2,015 $ 1,655 Cash dividends per common share $ 0.29 $ 0.27 On April 20, 2018, the Board of Directors declared a $0.31 per share cash dividend, payable on May 11, 2018 to shareholders of record at the close of business on May 4, 2018. Share-Based Payments The fair value of stock options as of the grant date is recorded as stock-based compensation expense in the consolidated statements of comprehensive income over the requisite service period with a corresponding increase in common stock. Stock-based compensation also includes compensation expense related to the issuance of restricted stock awards. The grant-date fair value of the restricted stock awards, which equals the intrinsic value on that date, is being recorded as compensation expense over the requisite service period with a corresponding increase in common stock as the shares vest. Performance-based stock awards (restricted stock awards) are issued to a selected group of employees. Stock award vesting is contingent upon the achievement of pre-established long-term performance goals set by the Compensation Committee of the Board of Directors. Performance is measured over a three -year period and the stock awards cliff vest. These performance-based stock awards were granted at a maximum opportunity level, and based on the achievement of the pre-established goals, the actual payouts can range from 0% to 200% of the target award. For performance-based stock awards, an estimate is made of the number of shares expected to vest based on the probability that the performance criteria will be achieved to determine the amount of compensation expense to be recognized. The estimate is re-evaluated quarterly and total compensation expense is adjusted for any change in the current period. In addition, we record excess tax benefits (deficiencies) resulting from the exercise of non-qualified stock options, the disqualifying disposition of incentive stock options and vesting of restricted stock awards as income tax benefits (expense) in the consolidated statements of comprehensive income with a corresponding decrease (increase) to current taxes payable. The holders of unvested restricted stock awards are entitled to dividends on the same per-share ratio as holders of common stock. Tax benefits on dividends paid on unvested restricted stock awards are recorded as tax benefits in the consolidated statements of comprehensive income with a corresponding decrease to current taxes payable. Under the 2017 Equity Plan, stock options may be net settled by a reduction in the number of shares otherwise deliverable upon exercise in satisfaction of the exercise payment and applicable tax withholding requirements. During the first three months of 2018, option holders exchanged 19,606 shares totaling $1.4 million at a weighted-average price of $70.36 for cashless stock option exercises and tax withholdings upon vesting of performance-based stock awards. During the first three months of 2017, option holders exchanged 4,715 shares totaling $324 thousand at a weighted-average price of $68.80 for cashless stock option exercises. Shares exchanged under net settlement arrangements are available for future grants under the 2017 Equity Plan. Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income We early adopted ASU No. 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income, in the first quarter of 2018 and reclassified $638 thousand from AOCI to retained earnings. This amount represents the stranded income tax effects related to the unrealized loss on available-for-sale securities in AOCI on the date of the enactment of the Tax Cuts and Jobs Act of 2017. For more information regarding ASU No. 2018-02, refer to Note 2, Accounting Standards Adopted in 2018. Share Repurchase Program On April 23, 2018, Bancorp announced that its Board of Directors approved a Share Repurchase Program under which Bancorp may repurchase up to $25.0 million of its outstanding common stock through May 1, 2019. Under the Share Repurchase Program, Bancorp may purchase shares of its common stock through various means such as open market transactions, including block purchases, and privately negotiated transactions. The number of shares repurchased and the timing, manner, price and amount of any repurchases will be determined at Bancorp's discretion. Factors include, but are not limited to, stock price, trading volume and general market conditions, along with Bancorp’s general business conditions. The program may be suspended or discontinued at any time and does not obligate Bancorp to acquire any specific number of shares of its common stock. As part of the Share Repurchase Program, Bancorp is entering into a trading plan adopted in accordance with Rule 10b5-1 of the Securities Exchange Act of 1934, as amended. The 10b5-1 trading plan permits common stock to be repurchased at a time that Bancorp might otherwise be precluded from doing so under insider trading laws or self-imposed trading restrictions. The 10b5-1 trading plan is administered by an independent broker and is subject to price, market volume and timing restrictions.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Financial Instruments with Off-Balance Sheet Risk We make commitments to extend credit in the normal course of business to meet the financing needs of our customers. These financial instruments include commitments to extend credit in the form of loans or through standby letters of credit. 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 or other termination clauses and may require payment of a fee. Because various commitments will expire without being fully drawn, the total commitment amount does not necessarily represent future cash requirements. Our credit loss exposure is equal to the contractual amount of the commitment in the event of nonperformance by the borrower. We use the same credit underwriting criteria for all credit exposure. The amount of collateral obtained, if deemed necessary by us, is based on Management's credit evaluation of the borrower. Collateral types pledged may include accounts receivable, inventory, other personal property and real property. The contractual amount of undrawn loan commitments and standby letters of credit not reflected on the consolidated statements of condition are as follows: (in thousands) March 31, 2018 December 31, 2017 Commercial lines of credit $ 226,816 $ 224,370 Revolving home equity lines 187,405 177,678 Undisbursed construction loans 24,315 35,322 Personal and other lines of credit 12,769 11,758 Standby letters of credit 2,539 4,074 Total commitments and standby letters of credit $ 453,844 $ 453,202 We record an allowance for losses on these off-balance sheet commitments based on an estimate of probabilities of the utilization of these commitments according to our historical experience on different types of commitments and expected loss. The allowance for losses on off-balance sheet commitments totaled $958 thousand as of March 31, 2018 and December 31, 2017 , which is recorded in interest payable and other liabilities on the consolidated statements of condition. Operating Leases We rent certain premises under long-term, non-cancelable operating leases expiring at various dates through the year 2032. Most of the leases contain certain renewal options and escalation clauses. At March 31, 2018 , the approximate minimum future commitments payable under non-cancelable contracts for leased premises are as follows: (in thousands) 2018 2019 2020 2021 2022 Thereafter Total Operating leases 1 $ 3,330 $ 4,198 $ 3,758 $ 2,138 $ 1,330 $ 2,904 $ 17,658 1 Minimum payments have not been reduced by minimum sublease rentals of $25 thousand due in the future under non-cancelable subleases. Rent expense included in occupancy expense totaled $1.0 million for the three months ended March 31, 2018 and 2017 . Litigation Matters We may be party to legal actions that arise from time to time during the normal course of business. We believe, after consultation with legal counsel, that litigation contingent liability, if any, would not have a material adverse effect on our consolidated financial position, results of operations, or cash flows. We are responsible for our proportionate share of certain litigation indemnifications provided to Visa U.S.A. ("Visa") by its member banks in connection with lawsuits related to anti-trust charges and interchange fees ("Covered Litigation"). In 2012, Visa had reached a $4.0 billion interchange multidistrict litigation class settlement agreement for which it maintains an escrow account to be used for settlements or judgments in the Covered Litigation. At March 31, 2018 , according to Visa's Form 10-Q filed on April 27, 2018, the escrow account balance was $0.9 billion . While the accrued liability related to the Covered Litigation could be higher or lower than the litigation escrow account balance, Visa did not record an additional accrual for the Covered Litigation during the first three months of 2018. In 2017, a number of class plaintiffs filed amended complaints for damages or filed new class complaints against Visa for injunctive relief. In addition, Wal-Mart Stores, Inc. entered into a new, unconditional settlement agreement with Visa in October 2017. As of the date of Visa's filing, it had reached settlement agreements with individual merchants representing 51% of the Visa-branded payment card sales volume of merchants who opted out of the 2012 settlement agreement. Litigation is ongoing and until the appeal process is complete, Visa is uncertain whether it will resolve the claims as contemplated by the settlement agreement and additional lawsuits may arise. The conversion rate of Visa Class B common stock held by us to Class A common stock (as discussed in Note 4, Investment Securities) may decrease if Visa makes more Covered Litigation settlement payments in the future, and the full effect on member banks is still uncertain. However, we are not aware of significant future cash settlement payments required by us on the Covered Litigation.

Derivative Financial Instrument

Derivative Financial Instruments and Hedging Activities	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments and Hedging Activities	Derivative Financial Instruments and Hedging Activities We have entered into interest rate swap agreements, primarily as an asset/liability management strategy, in order to mitigate the changes in the fair value of specified long-term fixed-rate loans (or firm commitments to enter into long-term fixed-rate loans) caused by changes in interest rates. These hedges allow us to offer long-term fixed-rate loans to customers without assuming the interest rate risk of a long-term asset. Converting our fixed-rate interest payments to floating-rate interest payments, generally benchmarked to the one-month U.S. dollar LIBOR index, protects us against changes in the fair value of our loans associated with fluctuating interest rates. Our credit exposure, if any, on interest rate swap asset positions is limited to the fair value (net of any collateral pledged to us) and interest payments of all swaps by each counterparty. Conversely, when an interest rate swap is in a liability position exceeding a certain threshold, we may be required to post collateral to the counterparty in an amount determined by the agreements. Collateral levels are monitored and adjusted on a regular basis for changes in interest rate swap values. As of March 31, 2018 , we had five interest rate swap agreements, which are scheduled to mature in June 2031, October 2031, July 2032, August 2037 and October 2037. All of our derivatives are accounted for as fair value hedges. The notional amounts of the interest rate contracts are equal to the notional amounts of the hedged loans. Our interest rate swap payments are settled monthly with counterparties. Accrued interest on the swaps totaled $7 thousand and $8 thousand as of March 31, 2018 and December 31, 2017 , respectively. Information on our derivatives follows: Asset derivatives Liability derivatives (in thousands) March 31, 2018 December 31, 2017 March 31, 2018 December 31, 2017 Fair value hedges: Interest rate contracts notional amount $ 9,171 $ 4,019 $ 9,429 $ 14,810 Interest rate contracts fair value 1 $ 239 $ 74 $ 376 $ 740 Three months ended (in thousands) March 31, 2018 March 31, 2017 Increase in value of designated interest rate swaps due to LIBOR interest rate movements recognized in interest income $ 529 $ 111 Payment on interest rate swaps recorded in interest income $ (55 ) $ (98 ) Decrease in value of hedged loans recognized in interest income $ (576 ) $ (113 ) Decrease in value of yield maintenance agreement recognized against interest income $ (4 ) $ (4 ) Net loss on derivatives recognized against interest income 2 $ (106 ) $ (104 ) 1 See Note 3, Fair Value of Assets and Liabilities, for valuation methodology. 2 Includes hedge ineffectiveness loss of $51 thousand and $6 thousand for the quarters ended March 31, 2018 and March 31, 2017 , respectively. Changes in value of swaps were included in the assessment of hedge effectiveness. Hedge ineffectiveness is the measure of the extent to which the change in the fair value of the hedging instruments does not exactly offset the change in the fair value of the hedged items from period to period. Our derivative transactions with counterparties are under International Swaps and Derivative Association (“ISDA”) master agreements that include “right of set-off” provisions. “Right of set-off” provisions are legally enforceable rights to offset recognized amounts and there may be an intention to settle such amounts on a net basis. We do not offset such financial instruments for financial reporting purposes. Information on financial instruments that are eligible for offset in the consolidated statements of condition follows: Offsetting of Financial Assets and Derivative Assets Gross Amounts Net Amounts of Gross Amounts Not Offset in Gross Amounts Offset in the Assets Presented the Statements of Condition of Recognized Statements of in the Statements Financial Cash Collateral ( in thousands) Assets 1 Condition of Condition 1 Instruments Received Net Amount March 31, 2018 Derivatives by Counterparty: Counterparty A $ 239 $ — $ 239 $ (239 ) $ — $ — December 31, 2017 Derivatives by Counterparty: Counterparty A $ 74 $ — $ 74 $ (74 ) $ — $ — 1 Amounts exclude accrued interest totaling $2 thousand and $1 thousand at March 31, 2018 and December 31, 2017 , respectively. Offsetting of Financial Liabilities and Derivative Liabilities Gross Amounts Net Amounts of Gross Amounts Not Offset in Gross Amounts Offset in the Liabilities Presented the Statements of Condition of Recognized Statements of in the Statements Financial Cash Collateral (in thousands) Liabilities 2 Condition of Condition 2 Instruments Pledged Net Amount March 31, 2018 Derivatives by Counterparty: Counterparty A $ 376 $ — $ 376 $ (239 ) $ (137 ) $ — December 31, 2017 Derivatives by Counterparty: Counterparty A $ 740 $ — $ 740 $ (74 ) $ (666 ) $ — 2 Amounts exclude accrued interest totaling $5 thousand and $8 thousand at March 31, 2018 and December 31, 2017 , respectively. For more information on how we account for our interest rate swaps, refer to Note 1 to the Consolidated Financial Statements included in our 2017 Form 10-K filed with the SEC on March 14, 2018.

Acquisition

Acquisition	3 Months Ended
	Mar. 31, 2018
Business Combinations [Abstract]
Acquisition	Acquisition On November 21, 2017, we completed the merger of Bank of Napa, N.A. (OTCQB: BNNP), to enhance our market presence in Napa, California. Bank of Napa was a national bank with two branch offices serving Napa. The acquisition added $134.7 million in loans, $249.9 million in deposits and $75.5 million in investment securities to Bank of Marin as of the acquisition date. Bank of Napa shareholders received 0.307 shares of Bancorp common stock for each share of Bank of Napa common stock outstanding. We have accounted for the acquisition of Bank of Napa as a business combination under the acquisition method of accounting. The assets acquired and liabilities assumed, both tangible and intangible, were recorded at their fair values as of the acquisition date in accordance with ASC 805, Business Combinations . The acquisition was treated as a "reorganization" within the definition of section 368(a) of the Internal Revenue Code and is generally considered tax-free for U.S. federal income tax purposes. The Bank of Napa acquisition resulted in $23.7 million in goodwill, which represents the excess of the total purchase price paid over the fair value of the assets acquired, net of the fair values of liabilities assumed. Goodwill mainly reflects expected value created through the combined operations of Bank of Napa and Bank of Marin, which we evaluate for impairment annually. We determined that the fair value of our traditional community banking activities (provided through our branch network) exceeded the carrying amount of the bank-level reporting unit. The goodwill is not deductible for tax purposes. The core deposit intangible represents the estimated future benefits of acquired deposits and is booked separately from the related deposits. We recorded a core deposit intangible asset of $4.4 million from the Bank of Napa acquisition on November 21, 2017, of which $56 thousand was amortized in 2017 and $127 thousand was amortized in the first quarter of 2018 . It is amortized on an accelerated basis over an estimated ten -year life, and is evaluated periodically for impairment. No impairment loss was recognized as of March 31, 2018 . Acquisition-related expenses are recognized as incurred and continue until all systems have been converted and operational functions become fully integrated. Bank of Marin Bancorp incurred acquisition-related expenses in the consolidated statements of comprehensive income for the three months ended March 31, 2018 as follows: (in thousands) Three months ended March 31, 2018 Data processing 1 $ 392 Professional services 95 Personnel severance 106 Other 22 Total $ 615 1 Primarily relates to Bank of Napa's core processing system contract termination and deconversion fees.

Basis of Presentation (Policies

Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	The consolidated financial statements include the accounts of Bank of Marin Bancorp (“Bancorp”), a bank holding company, and its wholly-owned bank subsidiary, Bank of Marin (the “Bank”), a California state-chartered commercial bank. References to “we,” “our,” “us” mean Bancorp and the Bank that are consolidated for financial reporting purposes. The accompanying unaudited consolidated interim financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission ("SEC"). Certain information and note disclosures normally included in annual financial statements prepared in accordance with U.S. generally accepted accounting principles ("GAAP") have been condensed or omitted pursuant to those rules and regulations. Although we believe that the disclosures are adequate and the information presented is not misleading, we suggest that these interim financial statements be read in conjunction with the annual financial statements and the notes thereto included in our 2017 Annual Report on Form 10-K. In the opinion of Management, the unaudited consolidated financial statements reflect all adjustments, which are necessary for a fair presentation of the consolidated financial position, the results of operations, changes in comprehensive income, changes in stockholders’ equity, and cash flows for the periods presented. All material intercompany transactions have been eliminated. The results of these interim periods may not be indicative of the results for the full year or for any other period. The NorCal Community Bancorp Trusts I and II, respectively (the "Trusts") were formed for the sole purpose of issuing trust preferred securities. Bancorp is not considered the primary beneficiary of the Trusts (variable interest entities), therefore the Trusts are not consolidated in our consolidated financial statements, but rather the subordinated debentures are shown as a liability on our consolidated statements of condition (See Note 6, Borrowings). Bancorp's investment in the securities of the Trusts is accounted for under the equity method and is included in i nterest receivable and other assets on the consolidated statements of condition.
Earnings Per Share	Basic earnings per share (“EPS”) are calculated by dividing net income by the weighted average number of common shares outstanding during each period, excluding unvested restricted stock awards. Diluted EPS are calculated using the weighted average number of potentially dilutive common shares. The number of potentially dilutive common shares included in year-to-date diluted EPS is a year-to-date weighted average of potentially dilutive common shares included in each quarterly diluted EPS computation. In computing diluted EPS, we exclude anti-dilutive shares such as options whose exercise prices exceed the current common stock price as they would not reduce EPS under the treasury method. We have two forms of outstanding common stock: common stock and unvested restricted stock awards. Holders of unvested restricted stock awards receive non-forfeitable dividends at the same rate as common shareholders and they both share equally in undistributed earnings. Under the two-class method, the difference in EPS is nominal for these participating securities.
Recently Issued Accounting Standards	In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers (Topic 606). The core principle of this ASU (and all subsequent updates) is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. This ASU establishes a five-step model that must be used to recognize revenue that requires the entity to 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 entity satisfies the performance obligation. The ASU does not apply to the majority of our revenue, including revenue associated with financial instruments, such as loans and investment securities, and certain non-interest income, such as earnings on bank-owned life insurance, dividends on Federal Home Loan Bank ("FHLB") stock, gains or losses on sales of investment securities, and deposit overdraft charges. The standard allowed the use of either the full retrospective or modified retrospective transition method. We elected to apply the modified retrospective transition method to incomplete contracts as of the initial date of application on January 1, 2018. The adoption of the new standards did not have a material impact on our financial condition or results of operations as the revenue recognition patterns under the new standards did not change significantly from our current practice of recognizing the in-scope non-interest income. In addition, we did not retroactively revise prior period amounts or record a cumulative adjustment to retained earnings upon adoption. We considered the nature, amount, timing, and uncertainty of revenue from contracts with customers and determined that significant revenue streams are sufficiently disaggregated in the consolidated statements of comprehensive income. Descriptions of our significant revenue-generating transactions that are within the scope of the new revenue recognition standards, which are presented in the consolidated statements of comprehensive income as components of non-interest income, are as follows: • Wealth Management & Trust ("WM&T") fees - WM&T services include, but are not limited to: customized investment advisory and management; administrative services such as bill pay and tax reporting; trust administration, estate settlement, custody and fiduciary services. Performance obligations for investment advisory and management services are generally satisfied over time. Revenue is recognized monthly according to a tiered fee schedule based on the client's month-end market value of assets under our management. WM&T does not earn revenue based on performance or incentives. Costs associated with WM&T revenue-generating activities, such as payments to sub-advisors, are recorded separately as part of professional service expenses when incurred. • Deposit account service charges - Service charges on deposit accounts consist of monthly maintenance fees, business account analysis fees, business online banking fees, check order charges, and other deposit account-related fees. Performance obligations for monthly maintenance fees and account analysis fees are satisfied, and the related revenue recognized, when our performance obligation is completed each month. Performance obligations related to transaction-based services (such as check orders) are satisfied, and the related revenue recognized, at a point in time when completed, except for business accounts subject to analysis where the transaction-based fees are part of the monthly account analysis fees. • Debit card interchange fees - We issue debit cards to our consumer and small business customers that allow them to purchase goods and services from merchants in person, online, or via mobile devices using funds held in their demand deposit accounts held with us. Debit cards issued to our customers are part of global electronic payment networks (such as Visa) who pass a portion of the merchant interchange fees to debit card-issuing member banks like us when our customers make purchases through their networks. Performance obligations for debit card services are satisfied, and revenue is recognized, daily as transactions are processed by the payment networks. Because we act in an agent capacity, we determined that network costs previously recorded as a component of non-interest expense should be netted with interchange fees recorded in non-interest income starting in the second quarter of 2018. Network costs were immaterial for the three months ended March 31, 2018 and 2017. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities . The amendments in this ASU make improvements to accounting standards related to financial instruments, including the following: • Requires equity investments, except for those accounted for under the equity method of accounting or those that result in consolidation of the investee, to be measured at fair value with changes in fair value recognized in net income. However, an entity may choose to measure equity investments that do not have readily determinable fair values at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. • Simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment. When impairment exists, an entity is required to measure the investment at fair value. • Eliminates the requirement to disclose the method(s) and significant assumptions used to estimate the fair value required under current standards for financial instruments measured at amortized cost on the consolidated balance sheet. • Requires public companies to use the exit price notion when measuring and disclosing the fair value of financial instruments. • Requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset (i.e., securities or loans and receivables) on the balance sheet or the accompanying notes to the financial statements. • Clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities in combination with the entity's other deferred tax assets. We adopted the requirements of this ASU effective January 1, 2018, which did not have a material impact on our financial condition and results of operations. The fair value of our loans held for investment, which is recorded at amortized cost, now incorporates the exit price notion reflecting factors such as a liquidity premium. See Note 3, Fair Value of Assets and Liabilities. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments . This ASU provides guidance on how to present and classify eight specific cash flow topics in the statement of cash flows. The ASU is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. The amendments should be applied using a retrospective transition method to each period presented, if practical. We adopted the requirements of this ASU effective January 1, 2018, which did not impact our financial condition, results of operations, or related financial statement disclosures for the periods presented. In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business . The amendments are intended to help companies evaluate whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses and provide a more robust framework to use in determining when a set of assets and activities is a business. The amendments should be applied prospectively and are effective for annual periods after December 31, 2017, including interim periods within those periods. We adopted the amendments effective January 1, 2018, which did not impact our financial condition, results of operations, or related financial statement disclosures in the first quarter of 2018. In May 2017, the FASB issued ASU No. 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting . This ASU applies to entities that change the terms or conditions of a share-based payment award. The FASB adopted this ASU to provide clarity in what constitutes a modification and to reduce diversity in practice in applying Topic 718. In order for a change to a share-based arrangement to not require Topic 718 modification accounting treatment, all of the following must be met: no change in fair value, no change in vesting conditions and no change in the balance sheet classification of the modified award. The ASU is effective for fiscal years beginning after December 15, 2017, including interim periods within those periods. Early adoption is permitted, including adoption in an interim period. The amendments should be applied prospectively to an award modified on or after the adoption date. We adopted the requirements of this ASU effective January 1, 2018, which did not impact our financial condition, results of operation, or related financial statement disclosures in the first quarter of 2018. In February 2018, the FASB issued ASU No. 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income . This amendment helps organizations address certain stranded income tax effects in accumulated other comprehensive income (AOCI) resulting from the enactment of the Tax Cuts and Jobs Act of 2017. The ASU requires financial statement preparers to disclose a description of the accounting policy for releasing income tax effects from AOCI, whether or not they elect to reclassify the stranded income tax effects from the Tax Cuts and Jobs Act of 2017, and information about the other income tax effects that are reclassified. The amendments are effective for all organizations for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The amendments in this ASU should be applied in either the period of adoption or retrospectively to each period (or periods) in which the effect of the change in the U.S. federal corporate tax rate in the Tax Cuts and Jobs Act of 2017 is recognized. We early adopted this ASU in the first quarter of 2018. See Note 7, Stockholders' Equity. Accounting Standards Not Yet Effective In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) . The amendments in this ASU intend to increase transparency and comparability among organizations by recognizing an asset, which represents the right to use the asset for the lease term, and a lease liability, which is a lessee's obligation to make lease payments measured on a discounted basis. This ASU generally applies to leasing arrangements exceeding a twelve month term. ASU 2016-02 is effective for annual periods, including interim periods within those annual periods beginning after December 15, 2018 and requires a modified retrospective method of adoption. Early application of the amendments is permitted. We intend to adopt this ASU during the first quarter of 2019, as required. We are continuing to evaluate our lease agreements and potential accounting software solutions as they become available. As of March 31, 2018, our undiscounted operating lease obligations that were off-balance sheet totaled $17.7 million (See Note 8, Commitments and Contingencies). Upon adoption of this ASU, the present values of leases currently classified as operating leases will be recognized as lease assets and liabilities on our consolidated balance sheets. Additional disclosures of key information about our leasing arrangements will also be required. We do not expect that the ASU will have a material impact on our capital ratios or return on average assets when adopted and we are currently evaluating the effect that the ASU will have on other components of our financial condition and results of operations. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . Under the new guidance, entities will be required to measure expected credit losses by utilizing forward-looking information to assess an entity's allowance for credit losses. The measurement of expected credit losses will be based on historical experience, current conditions and reasonable and supportable forecasts that affect the collectability of a credit over its remaining life. In addition, the ASU amends the accounting for potential credit losses on available-for-sale debt securities and purchased financial assets with credit deterioration. ASU 2016-13 is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. We have formed an internal Current Expected Credit Loss ("CECL") committee and are working with our third party vendor to determine the appropriate methodologies and resources to utilize in preparation for transition to the new accounting standards. In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities . This amendment changes both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. It is intended to more closely align hedge accounting with companies' risk management strategies, simplify the application of hedge accounting, and increase transparency as to the scope and results of hedging programs. The ASU is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. The amended presentation and disclosure guidance will be required prospectively. We expect this amendment to affect the presentation of our hedging activities, but we do not expect it to have a material impact on our financial condition or results of operations.
Fair Value Measurement	We group our assets and liabilities that are measured at fair value in three levels within the fair value hierarchy, based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. These levels are: Level 1: Valuations are based on unadjusted quoted prices in active markets for identical assets or liabilities. Level 2: Valuations are based on quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active and model-based valuations for which all significant assumptions are observable or can be corroborated by observable market data. Level 3: Valuations are based on unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Values are determined using pricing models and discounted cash flow models and may include significant Management judgment and estimation. Transfers between levels of the fair value hierarchy are recognized through our monthly and/or quarterly valuation process in the reporting period during which the event or circumstances that caused the transfer occurred.
Finance, Loan and Lease Receivables, Held-for-investment, Allowance and Nonperforming Loans	We generally make commercial loans to established small and mid-sized businesses to provide financing for their growth and working capital needs, equipment purchases and acquisitions. Management examines historical, current, and projected cash flows to determine the ability of the borrower to repay obligations as agreed. Commercial loans are made based primarily on the identified cash flows of the borrower and secondarily on the underlying collateral and guarantor support. The cash flows of borrowers, however, may not occur as expected, and the collateral securing these loans may fluctuate in value. Most commercial and industrial loans are secured by the assets being financed, such as accounts receivable and inventory, and typically include a personal guarantee. We target stable businesses with guarantors who provide additional sources of repayment and have proven to be resilient in periods of economic stress. Commercial real estate loans are subject to underwriting standards and processes similar to commercial loans discussed above. We underwrite these loans to be repaid from cash flow and to be supported by real property collateral. Underwriting standards for commercial real estate loans include, but are not limited to, debt coverage and loan-to-value ratios. Furthermore, the owners of the properties guarantee substantially all of our commercial real estate loans. Conditions in the real estate markets or in the general economy may adversely affect our commercial real estate loans. In the event of a vacancy, we expect guarantors to carry the loans until they find a replacement tenant. The owner's substantial equity investment provides a strong economic incentive to continue to support the commercial real estate projects. As such, we have generally experienced a relatively low level of loss and delinquencies in this portfolio. We generally make construction loans to developers and builders to finance construction, renovation and occasionally land acquisitions in anticipation of near-term development. These loans are underwritten after evaluation of the borrower's financial strength, reputation, prior track record, and independent appraisals. Significant events can affect the construction industry, including: the inherent volatility of real estate markets and vulnerability to delays due to weather, change orders, inability to obtain construction permits, labor or material shortages, and price changes. Estimates of construction costs and value associated with the completed project may be inaccurate. Repayment of construction loans is largely dependent on the ultimate success of the project. Consumer loans primarily consist of home equity lines of credit, other residential loans and floating homes, along with a small number of installment loans. Our other residential loans include tenancy-in-common fractional interest loans ("TIC") located almost entirely in San Francisco County. We originate consumer loans utilizing credit score information, debt-to-income ratio and loan-to-value ratio analysis. Diversification among consumer loan types, coupled with relatively small loan amounts that are spread across many individual borrowers, mitigates risk. We use a risk rating system to evaluate asset quality, and to identify and monitor credit risk in individual loans, and in the loan portfolio. Our definitions of “Special Mention” risk graded loans, or worse, are consistent with those used by the Federal Deposit Insurance Corporation ("FDIC"). Our internally assigned grades are as follows: Pass and Watch : Loans to borrowers of acceptable or better credit quality. Borrowers in this category demonstrate fundamentally sound financial positions, repayment capacity, credit history and management expertise. Loans in this category must have an identifiable and stable source of repayment and meet the Bank’s policy regarding debt-service-coverage ratios. These borrowers are capable of sustaining normal economic, market or operational setbacks without significant financial consequences. Negative external industry factors are generally not present. The loan may be secured, unsecured or supported by non-real estate collateral for which the value is more difficult to determine and/or marketability is more uncertain. This category also includes “Watch” loans, where the primary source of repayment has been delayed. “Watch” is intended to be a transitional grade, with either an upgrade or downgrade within a reasonable period. Special Mention : Potential weaknesses that deserve close attention. If left uncorrected, those potential weaknesses may result in deterioration of the payment prospects for the asset. Special Mention assets do not present sufficient risk to warrant adverse classification. Substandard : Inadequately protected by either the current sound worth and paying capacity of the obligor or the collateral pledged, if any. A Substandard asset has a well-defined weakness or weaknesses that jeopardize(s) the liquidation of the debt. Substandard assets are characterized by the distinct possibility that we will sustain some loss if such weaknesses or deficiencies are not corrected. Well-defined weaknesses include adverse trends or developments of the borrower’s financial condition, managerial weaknesses and/or significant collateral deficiencies. Doubtful : Critical weaknesses that make collection or liquidation in full improbable. There may be specific pending events that work to strengthen the asset; however, the amount or timing of the loss may not be determinable. Pending events generally occur within one year of the asset being classified as Doubtful. Examples include: merger, acquisition, or liquidation; capital injection; guarantee; perfecting liens on additional collateral; and refinancing. Such loans are placed on non-accrual status and usually are collateral-dependent. We regularly review our credits for accuracy of risk grades whenever we receive new information. Borrowers are required to submit financial information at regular intervals. Generally, commercial borrowers with lines of credit are required to submit financial information with reporting intervals ranging from monthly to annually depending on credit size, risk and complexity. Investor commercial real estate borrowers are generally required to submit rent rolls or property income statements annually. We monitor construction loans monthly and review them on an ongoing basis. We review home equity and other consumer loans based on delinquency status. We also review loans graded “Watch” or worse, regardless of loan type, no less than quarterly.
Troubled Debt Restructuring	Our loan portfolio includes certain loans modified in a troubled debt restructuring (“TDR”), where we have granted economic concessions to borrowers experiencing financial difficulties. These concessions typically result from our loss mitigation activities and could include reductions in the interest rate, payment extensions, forgiveness of principal, forbearance or other actions. TDRs on non-accrual status at the time of restructure may be returned to accruing status after Management considers the borrower’s sustained repayment performance for a reasonable period, generally six months, and obtains reasonable assurance of repayment and performance. We may remove a loan from TDR designation if it meets all of the following conditions: • The loan is subsequently refinanced or restructured at current market interest rates and the new terms are consistent with the treatment of creditworthy borrowers under regular underwriting standards; • The borrower is no longer considered to be in financial difficulty; • Performance on the loan is reasonably assured; and; • Existing loan did not have any forgiveness of principal or interest. The same Management level that approved the upgrading of the loan classification must approve the removal of TDR status.

Basis of Presentation (Tables)

Basis of Presentation (Tables)	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Earnings Per Share Reconciliation	The following table shows: 1) weighted average basic shares, 2) potentially dilutive weighted average common shares related to stock options and unvested restricted stock awards, and 3) weighted average diluted shares. Basic earnings per share (“EPS”) are calculated by dividing net income by the weighted average number of common shares outstanding during each period, excluding unvested restricted stock awards. Diluted EPS are calculated using the weighted average number of potentially dilutive common shares. The number of potentially dilutive common shares included in year-to-date diluted EPS is a year-to-date weighted average of potentially dilutive common shares included in each quarterly diluted EPS computation. In computing diluted EPS, we exclude anti-dilutive shares such as options whose exercise prices exceed the current common stock price as they would not reduce EPS under the treasury method. We have two forms of outstanding common stock: common stock and unvested restricted stock awards. Holders of unvested restricted stock awards receive non-forfeitable dividends at the same rate as common shareholders and they both share equally in undistributed earnings. Under the two-class method, the difference in EPS is nominal for these participating securities. Three months ended (in thousands, except per share data) March 31, 2018 March 31, 2017 Weighted average basic shares outstanding 6,914 6,092 Potentially dilutive common shares related to: Stock options 75 62 Unvested restricted stock awards 17 18 Weighted average diluted shares outstanding 7,006 6,172 Net income $ 6,389 $ 4,548 Basic EPS $ 0.92 $ 0.75 Diluted EPS $ 0.91 $ 0.74 Weighted average anti-dilutive shares not included in the calculation of diluted EPS 32 13

Fair Value of Assets and Liab20

Fair Value of Assets and Liabilities (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following table summarizes our assets and liabilities that were required to be recorded at fair value on a recurring basis. (in thousands) Description of Financial Instruments Carrying Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Measurement Categories: Changes in Fair Value Recorded In 1 March 31, 2018 Securities available-for-sale: Mortgage-backed securities and collateralized mortgage obligations issued by U.S. government agencies $ 262,666 $ — $ 262,666 $ — OCI SBA-backed securities 33,538 — 33,373 165 OCI Debentures of government sponsored agencies 27,336 — 27,336 — OCI Privately-issued collateralized mortgage obligations 1,390 — 1,390 — OCI Obligations of state and political subdivisions 93,414 — 93,414 — OCI Corporate bonds 5,538 — 5,538 — OCI Derivative financial assets (interest rate contracts) 239 — 239 — NI Derivative financial liabilities (interest rate contracts) 376 — 376 — NI December 31, 2017 Securities available-for-sale: Mortgage-backed securities and collateralized mortgage obligations issued by U.S. government agencies $ 188,061 $ — $ 188,061 $ — OCI SBA-backed securities 25,982 25,817 165 OCI Debentures of government sponsored agencies 12,938 — 12,938 — OCI Privately-issued collateralized mortgage obligations 1,431 — 1,431 — OCI Obligations of state and political subdivisions 97,491 — 97,491 — OCI Corporate bonds 6,564 — 6,564 — OCI Derivative financial assets (interest rate contracts) 74 — 74 — NI Derivative financial liabilities (interest rate contracts) 740 — 740 — NI 1 Other comprehensive income ("OCI") or net income ("NI").
Fair Value, by Balance Sheet Grouping	The following table summarizes fair value estimates for financial instruments as of March 31, 2018 and December 31, 2017 , excluding financial instruments recorded at fair value on a recurring basis (summarized in the first table in this note). The carrying amounts in the following table are recorded in the consolidated statements of condition under the indicated captions. Further, we have not disclosed the fair value of financial instruments specifically excluded from disclosure requirements such as bank-owned life insurance policies ("BOLI") and non-maturity deposit liabilities. Additionally, we hold shares of FHLB stock and Visa Inc. Class B common stock at cost. These shares are restricted from resale, except among member banks, and their values are discussed in Note 4, Investment Securities . March 31, 2018 December 31, 2017 (in thousands) Carrying Amounts Fair Value Fair Value Hierarchy Carrying Amounts Fair Value Fair Value Hierarchy Financial assets (recorded at amortized cost) Cash and cash equivalents $ 159,347 $ 159,347 Level 1 $ 203,545 $ 203,545 Level 1 Investment securities held-to-maturity 149,013 145,818 Level 2 151,032 151,032 Level 2 Loans, net 1,655,969 1,622,552 Level 3 1,663,246 1,650,198 Level 3 Interest receivable 7,087 7,087 Level 2 7,501 7,501 Level 2 Financial liabilities (recorded at amortized cost) Time deposits 145,942 145,212 Level 2 160,116 159,540 Level 2 Subordinated debentures 5,772 6,820 Level 3 5,739 5,118 Level 3 Interest payable 172 172 Level 2 191 191 Level 2

Investment Securities (Tables)

Investment Securities (Tables)	3 Months Ended
	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Held-to-maturity Securities	Our investment securities portfolio consists of obligations of state and political subdivisions, corporate bonds, U.S. government agency securities, including residential and commercial mortgage-backed securities (“MBS”) and collateralized mortgage obligations (“CMOs”) issued or guaranteed by Federal National Mortgage Association ("FNMA"), Federal Home Loan Mortgage Corporation ("FHLMC"), or Government National Mortgage Association ("GNMA"), debentures issued by government-sponsored agencies such as FNMA, Federal Farm Credit Bureau, FHLB and FHLMC, as well as privately issued CMOs, as reflected in the following table: March 31, 2018 December 31, 2017 Amortized Fair Gross Unrealized Amortized Fair Gross Unrealized (in thousands) Cost Value Gains (Losses) Cost Value Gains (Losses) Held-to-maturity: Obligations of state and political subdivisions $ 19,599 $ 19,857 $ 278 $ (20 ) $ 19,646 $ 19,998 $ 383 $ (31 ) MBS pass-through securities issued by FHLMC and FNMA 97,222 94,735 12 (2,499 ) 100,376 100,096 234 (514 ) CMOs issued by FHLMC 32,192 31,226 1 (967 ) 31,010 30,938 2 (74 ) Total held-to-maturity 149,013 145,818 291 (3,486 ) 151,032 151,032 619 (619 ) Available-for-sale: Securities of U.S. government agencies: MBS pass-through securities issued by FHLMC and FNMA 93,915 92,029 22 (1,908 ) 65,559 65,262 126 (423 ) SBA-backed securities 33,809 33,538 8 (279 ) 25,979 25,982 58 (55 ) CMOs issued by FNMA 34,210 33,613 9 (606 ) 35,340 35,125 33 (248 ) CMOs issued by FHLMC 123,007 120,374 60 (2,693 ) 70,514 69,889 3 (628 ) CMOs issued by GNMA 17,173 16,650 5 (528 ) 17,953 17,785 26 (194 ) Debentures of government- sponsored agencies 27,446 27,336 6 (116 ) 12,940 12,938 3 (5 ) Privately issued CMOs 1,389 1,390 3 (2 ) 1,432 1,431 1 (2 ) Obligations of state and political subdivisions 95,395 93,414 99 (2,080 ) 98,027 97,491 298 (834 ) Corporate bonds 5,527 5,538 27 (16 ) 6,541 6,564 26 (3 ) Total available-for-sale 431,871 423,882 239 (8,228 ) 334,285 332,467 574 (2,392 ) Total investment securities $ 580,884 $ 569,700 $ 530 $ (11,714 ) $ 485,317 $ 483,499 $ 1,193 $ (3,011 )
Available-for-sale Securities	Our investment securities portfolio consists of obligations of state and political subdivisions, corporate bonds, U.S. government agency securities, including residential and commercial mortgage-backed securities (“MBS”) and collateralized mortgage obligations (“CMOs”) issued or guaranteed by Federal National Mortgage Association ("FNMA"), Federal Home Loan Mortgage Corporation ("FHLMC"), or Government National Mortgage Association ("GNMA"), debentures issued by government-sponsored agencies such as FNMA, Federal Farm Credit Bureau, FHLB and FHLMC, as well as privately issued CMOs, as reflected in the following table: March 31, 2018 December 31, 2017 Amortized Fair Gross Unrealized Amortized Fair Gross Unrealized (in thousands) Cost Value Gains (Losses) Cost Value Gains (Losses) Held-to-maturity: Obligations of state and political subdivisions $ 19,599 $ 19,857 $ 278 $ (20 ) $ 19,646 $ 19,998 $ 383 $ (31 ) MBS pass-through securities issued by FHLMC and FNMA 97,222 94,735 12 (2,499 ) 100,376 100,096 234 (514 ) CMOs issued by FHLMC 32,192 31,226 1 (967 ) 31,010 30,938 2 (74 ) Total held-to-maturity 149,013 145,818 291 (3,486 ) 151,032 151,032 619 (619 ) Available-for-sale: Securities of U.S. government agencies: MBS pass-through securities issued by FHLMC and FNMA 93,915 92,029 22 (1,908 ) 65,559 65,262 126 (423 ) SBA-backed securities 33,809 33,538 8 (279 ) 25,979 25,982 58 (55 ) CMOs issued by FNMA 34,210 33,613 9 (606 ) 35,340 35,125 33 (248 ) CMOs issued by FHLMC 123,007 120,374 60 (2,693 ) 70,514 69,889 3 (628 ) CMOs issued by GNMA 17,173 16,650 5 (528 ) 17,953 17,785 26 (194 ) Debentures of government- sponsored agencies 27,446 27,336 6 (116 ) 12,940 12,938 3 (5 ) Privately issued CMOs 1,389 1,390 3 (2 ) 1,432 1,431 1 (2 ) Obligations of state and political subdivisions 95,395 93,414 99 (2,080 ) 98,027 97,491 298 (834 ) Corporate bonds 5,527 5,538 27 (16 ) 6,541 6,564 26 (3 ) Total available-for-sale 431,871 423,882 239 (8,228 ) 334,285 332,467 574 (2,392 ) Total investment securities $ 580,884 $ 569,700 $ 530 $ (11,714 ) $ 485,317 $ 483,499 $ 1,193 $ (3,011 )
Investments Classified by Contractual Maturity Date	The amortized cost and fair value of investment debt securities by contractual maturity at March 31, 2018 are shown in the following table. Expected maturities may differ from contractual maturities if the issuers of the securities have the right to call or prepay obligations with or without call or prepayment penalties. March 31, 2018 December 31, 2017 Held-to-Maturity Available-for-Sale Held-to-Maturity Available-for-Sale (in thousands) Amortized Cost Fair Value Amortized Cost Fair Value Amortized Cost Fair Value Amortized Cost Fair Value Within one year $ 3,230 $ 3,256 $ 10,291 $ 10,281 $ 2,151 $ 2,172 $ 10,268 $ 10,272 After one but within five years 14,458 14,599 77,606 76,619 15,577 15,791 71,576 71,237 After five years through ten years 53,048 51,589 225,526 220,904 54,641 54,554 129,723 128,954 After ten years 78,277 76,374 118,448 116,078 78,663 78,515 122,718 122,004 Total $ 149,013 $ 145,818 $ 431,871 $ 423,882 $ 151,032 $ 151,032 $ 334,285 $ 332,467
Schedule of Financial Instruments Owned and Pledged as Collateral	Pledged investment securities are shown in the following table: (in thousands) March 31, 2018 December 31, 2017 Pledged to the State of California: Secure public deposits in compliance with the Local Agency Security Program $ 102,738 $ 107,829 Collateral for trust deposits 754 761 Total investment securities pledged to the State of California $ 103,492 $ 108,590 Collateral for Wealth Management and Trust Services ("WMTS") checking account $ 2,018 $ 2,026
Schedule of Unrealized Loss on Investments	There were 258 and 198 investment securities in unrealized loss positions at March 31, 2018 and December 31, 2017 , respectively. Those securities are summarized and classified according to the duration of the loss period in the following tables: March 31, 2018 < 12 continuous months ≥ 12 continuous months Total securities in a loss position (in thousands) Fair value Unrealized loss Fair value Unrealized loss Fair value Unrealized loss Held-to-maturity: Obligations of state and political subdivisions $ 3,636 $ (20 ) $ — $ — $ 3,636 $ (20 ) MBS pass-through securities issued by FHLMC and FNMA 22,570 (611 ) 69,808 (1,888 ) 92,378 (2,499 ) CMOs issued by FHLMC 16,571 (445 ) 12,667 (522 ) 29,238 (967 ) Total held-to-maturity 42,777 (1,076 ) 82,475 (2,410 ) 125,252 (3,486 ) Available-for-sale: MBS pass-through securities issued by FHLMC and FNMA 71,449 (1,314 ) 18,895 (594 ) 90,344 (1,908 ) SBA-backed securities 24,816 (277 ) 165 (2 ) 24,981 (279 ) CMOs issued by FNMA 28,289 (473 ) 5,061 (133 ) 33,350 (606 ) CMOs issued by FHLMC 107,801 (2,693 ) — — 107,801 (2,693 ) CMOs issued by GNMA 15,955 (528 ) — — 15,955 (528 ) Debentures of government- sponsored agencies 12,330 (116 ) — — 12,330 (116 ) Privately issued CMOs 862 (2 ) — — 862 (2 ) Obligations of state and political subdivisions 63,831 (920 ) 18,880 (1,160 ) 82,711 (2,080 ) Corporate bonds 4,032 (16 ) — — 4,032 (16 ) Total available-for-sale 329,365 (6,339 ) 43,001 (1,889 ) 372,366 (8,228 ) Total temporarily impaired securities $ 372,142 $ (7,415 ) $ 125,476 $ (4,299 ) $ 497,618 $ (11,714 ) December 31, 2017 < 12 continuous months ≥ 12 continuous months Total securities in a loss position (in thousands) Fair value Unrealized loss Fair value Unrealized loss Fair value Unrealized loss Held-to-maturity: Obligations of state and political subdivisions $ 3,648 $ (31 ) $ — $ — $ 3,648 $ (31 ) MBS pass-through securities issued by FHLMC and FNMA $ 16,337 $ (143 ) $ 46,845 $ (371 ) $ 63,182 $ (514 ) CMOs issued by FHLMC 11,066 (31 ) 13,824 (43 ) 24,890 (74 ) Total held-to-maturity 31,051 (205 ) 60,669 (414 ) 91,720 (619 ) Available-for-sale: MBS pass-through securities issued by FHLMC and FNMA 32,189 (121 ) 15,325 (302 ) 47,514 (423 ) SBA-backed securities 11,028 (53 ) 165 (2 ) 11,193 (55 ) CMOs issued by FNMA 26,401 (171 ) 5,440 (77 ) 31,841 (248 ) CMOs issued by FHLMC 69,276 (628 ) — — 69,276 (628 ) CMOs issued by GNMA 14,230 (194 ) — — 14,230 (194 ) Debentures of government- sponsored agencies 2,984 (5 ) — — 2,984 (5 ) Privately issued CMO's 1,310 (2 ) — — 1,310 (2 ) Obligations of state and political subdivisions 52,197 (288 ) 19,548 (546 ) 71,745 (834 ) Corporate bonds 3,060 (3 ) — — 3,060 (3 ) Total available-for-sale 212,675 (1,465 ) 40,478 (927 ) 253,153 (2,392 ) Total temporarily impaired securities $ 243,726 $ (1,670 ) $ 101,147 $ (1,341 ) $ 344,873 $ (3,011 )

Loans and Allowance for Loan 22

Loans and Allowance for Loan Losses (Tables)	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Past Due Financing Receivables	The following table shows outstanding loans by class and payment aging as of March 31, 2018 and December 31, 2017 . Loan Aging Analysis by Loan Class (in thousands) Commercial and industrial Commercial real estate, owner-occupied Commercial real estate, investor Construction Home equity Other residential 1 Installment and other consumer Total March 31, 2018 30-59 days past due $ — $ — $ — $ — $ 385 $ — $ — $ 385 60-89 days past due 4 — — — — — — 4 90 days or more past due — — — — — — — — Total past due 4 — — — 385 — — 389 Current 231,676 300,377 828,945 64,978 124,314 95,621 25,440 1,671,351 Total loans 3 $ 231,680 $ 300,377 $ 828,945 $ 64,978 $ 124,699 $ 95,621 $ 25,440 $ 1,671,740 Non-accrual loans 2 $ — $ — $ — $ — $ 392 $ — $ — $ 392 December 31, 2017 30-59 days past due $ — $ — $ — $ — $ 99 $ 255 $ 330 $ 684 60-89 days past due 1,340 — — — — — — 1,340 90 days or more past due — — — — 307 — — 307 Total past due 1,340 — — — 406 255 330 2,331 Current 234,495 300,963 822,984 63,828 132,061 95,271 27,080 1,676,682 Total loans 3 $ 235,835 $ 300,963 $ 822,984 $ 63,828 $ 132,467 $ 95,526 $ 27,410 $ 1,679,013 Non-accrual loans 2 $ — $ — $ — $ — $ 406 $ — $ — $ 406 1 Our residential loan portfolio does not include sub-prime loans, nor is it our practice to underwrite loans commonly referred to as "Alt-A mortgages", the characteristics of which are loans lacking full documentation, borrowers having low FICO scores or higher loan-to-value ratios. 2 One purchased credit impaired ("PCI") loan with an unpaid balance of $11 thousand and no carrying value was not accreting interest at March 31, 2018 . Three PCI loans with unpaid balances totaling $131 thousand and no carrying values were not accreting interest at December 31, 2017 . Amounts exclude accreting PCI loans totaling $2.1 million at both March 31, 2018 and December 31, 2017 as we have a reasonable expectation about future cash flows to be collected and we continue to recognize accretable yield on these loans in interest income. There were no accruing loans past due more than ninety days at March 31, 2018 or December 31, 2017 . 3 Amounts include net deferred loan origination costs of $928 thousand and $818 thousand at March 31, 2018 and December 31, 2017 , respectively. Amounts are also net of unaccreted purchase discounts on non-PCI loans of $1.1 million and $1.2 million at March 31, 2018 and December 31, 2017 , respectively.
Financing Receivable Credit Quality Indicators	The following table represents an analysis of the carrying amount in loans, net of deferred fees and costs and purchase premiums or discounts, by internally assigned risk grades, including PCI loans, at March 31, 2018 and December 31, 2017 . Credit Risk Profile by Internally Assigned Risk Grade (in thousands) Commercial and industrial Commercial real estate, owner-occupied Commercial real estate, investor Construction Home equity Other residential Installment and other consumer Purchased credit-impaired Total March 31, 2018 Pass $ 213,676 $ 279,899 $ 824,867 $ 62,003 $ 122,760 $ 95,621 $ 25,339 $ 1,338 $ 1,625,503 Special Mention 4,761 9,918 2,954 — — — — 797 18,430 Substandard 13,191 9,366 327 2,975 1,847 — 101 — 27,807 Total loans $ 231,628 $ 299,183 $ 828,148 $ 64,978 $ 124,607 $ 95,621 $ 25,440 $ 2,135 $ 1,671,740 December 31, 2017 Pass $ 214,636 $ 281,104 $ 818,570 $ 60,859 $ 130,558 $ 95,526 $ 27,287 $ 1,325 $ 1,629,865 Special Mention 9,318 9,284 1,850 — — — — 790 21,242 Substandard 11,816 9,409 1,774 2,969 1,815 — 123 — 27,906 Total loans $ 235,770 $ 299,797 $ 822,194 $ 63,828 $ 132,373 $ 95,526 $ 27,410 $ 2,115 $ 1,679,013
Troubled Debt Restructurings on Financing Receivables	The following table summarizes the carrying amount of TDR loans by loan class as of March 31, 2018 and December 31, 2017 . (in thousands) Recorded investment in Troubled Debt Restructurings 1 March 31, 2018 December 31, 2017 Commercial and industrial $ 2,267 $ 2,165 Commercial real estate, owner-occupied 7,007 6,999 Commercial real estate, investor 1,854 2,171 Construction 2,976 2,969 Home equity 347 347 Other residential 992 1,148 Installment and other consumer 712 721 Total $ 16,155 $ 16,520 1 There were no TDR loans on non-accrual status at March 31, 2018 and December 31, 2017 . The following table presents information for loans modified in a TDR during the presented periods, including the number of modified contracts, the recorded investment in the loans prior to modification, and the recorded investment in the loans at period end after being restructured. The following table excludes fully charged-off TDR loans and loans modified in a TDR and subsequently paid-off during the years presented. (dollars in thousands) Number of Contracts Modified Pre-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment Post-Modification Outstanding Recorded Investment at Period End Troubled Debt Restructurings during the three months ended March 31, 2018: None — $ — $ — $ — Troubled Debt Restructurings during the three months ended March 31, 2017: Installment and other consumer 1 $ 50 $ 50 $ 50
Impaired Financing Receivables	The following tables summarize information by class on impaired loans and their related allowances. Total impaired loans include non-accrual loans, accruing TDR loans and accreting PCI loans that have experienced post-acquisition declines in cash flows expected to be collected. (in thousands) Commercial and industrial Commercial real estate, owner-occupied Commercial real estate, investor Construction Home equity Other residential Installment and other consumer Total March 31, 2018 Recorded investment in impaired loans: With no specific allowance recorded $ 307 $ — $ — $ 2,692 $ 392 $ 992 $ 46 $ 4,429 With a specific allowance recorded 1,960 7,007 1,854 284 347 — 666 12,118 Total recorded investment in impaired loans $ 2,267 $ 7,007 $ 1,854 $ 2,976 $ 739 $ 992 $ 712 $ 16,547 Unpaid principal balance of impaired loans $ 2,260 $ 6,993 $ 1,847 $ 2,962 $ 736 $ 991 $ 711 $ 16,500 Specific allowance 35 162 48 11 6 — 92 354 Average recorded investment in impaired loans during the quarter ended 2,216 7,003 2,012 2,972 746 1,070 717 16,736 Interest income recognized on impaired loans during the quarter ended 1 155 66 22 38 5 13 7 306 Average recorded investment in impaired loans during the quarter ended 2,138 6,997 2,783 3,243 713 1,571 939 18,384 Interest income recognized on impaired loans during the quarter ended 1 23 66 23 34 8 19 10 183 1 Interest income recognized on a cash basis totaled $128 thousand in the first quarter of 2018 and was related to the pay-off of two non-accrual commercial PCI loans. No interest income on impaired loans was recognized on a cash basis during the three months ended March 31, 2017. (in thousands) Commercial and industrial Commercial real estate, owner-occupied Commercial real estate, investor Construction Home equity Other residential Installment and other consumer Total December 31, 2017 Recorded investment in impaired loans: With no specific allowance recorded $ 309 $ — $ — $ 2,689 $ 406 $ 995 $ 46 $ 4,445 With a specific allowance recorded 1,856 6,999 2,171 280 347 153 675 12,481 Total recorded investment in impaired loans $ 2,165 $ 6,999 $ 2,171 $ 2,969 $ 753 $ 1,148 $ 721 $ 16,926 Unpaid principal balance of impaired loans $ 2,278 $ 6,993 $ 2,168 $ 2,963 $ 750 $ 1,147 $ 720 $ 17,019 Specific allowance $ 50 $ 188 $ 159 $ 7 $ 6 $ 1 $ 102 $ 513
Allowance for Credit Losses on Financing Receivables	The following tables disclose activity in the allowance for loan losses ("ALLL") and the recorded investment in loans by class, as well as the related ALLL disaggregated by impairment evaluation method. Allowance for Loan Losses Rollforward for the Period (in thousands) Commercial and industrial Commercial real estate, owner-occupied Commercial real estate, investor Construction Home equity Other residential Installment and other consumer Unallocated Total Three months ended March 31, 2018 Beginning balance $ 3,654 $ 2,294 $ 6,475 $ 681 $ 1,031 $ 536 $ 378 $ 718 $ 15,767 Provision (reversal) 35 (214 ) (20 ) 16 (52 ) 7 (27 ) 255 — Charge-offs — — — — — — — — — Recoveries 4 — — — — — — — 4 Ending balance $ 3,693 $ 2,080 $ 6,455 $ 697 $ 979 $ 543 $ 351 $ 973 $ 15,771 Three months ended March 31, 2017 Beginning balance $ 3,248 $ 1,753 $ 6,320 $ 781 $ 973 $ 454 $ 372 $ 1,541 $ 15,442 Provision (reversal) 1,386 239 (187 ) (235 ) 17 (10 ) (11 ) (1,199 ) — Charge-offs (284 ) — — — — — (3 ) — (287 ) Recoveries 63 — — — — — 1 — 64 Ending balance $ 4,413 $ 1,992 $ 6,133 $ 546 $ 990 $ 444 $ 359 $ 342 $ 15,219 Allowance for Loan Losses and Recorded Investment in Loans (dollars in thousands) Commercial and industrial Commercial real estate, owner-occupied Commercial real estate, investor Construction Home equity Other residential Installment and other consumer Unallocated Total March 31, 2018 Ending ALLL related to loans collectively evaluated for impairment $ 3,658 $ 1,918 $ 6,407 $ 686 $ 973 $ 543 $ 259 $ 973 $ 15,417 Ending ALLL related to loans individually evaluated for impairment 35 162 48 11 6 — 92 — 354 Ending ALLL related to purchased credit-impaired loans — — — — — — — — — Ending balance $ 3,693 $ 2,080 $ 6,455 $ 697 $ 979 $ 543 $ 351 $ 973 $ 15,771 Recorded Investment: Collectively evaluated for impairment $ 229,361 $ 292,176 $ 826,294 $ 62,002 $ 123,868 $ 94,629 $ 24,728 $ — $ 1,653,058 Individually evaluated for impairment 2,267 7,007 1,854 2,976 739 992 712 — 16,547 Purchased credit-impaired 52 1,194 797 — 92 — — — 2,135 Total $ 231,680 $ 300,377 $ 828,945 $ 64,978 $ 124,699 $ 95,621 $ 25,440 $ — $ 1,671,740 Ratio of allowance for loan losses to total loans 1.59 % 0.69 % 0.78 % 1.07 % 0.79 % 0.57 % 1.38 % NM 0.94 % Allowance for loan losses to non-accrual loans NM NM NM NM 250 % NM NM NM 4,023 % NM - Not Meaningful Allowance for Loan Losses and Recorded Investment in Loans (dollars in thousands) Commercial and industrial Commercial real estate, owner-occupied Commercial real estate, investor Construction Home equity Other residential Installment and other consumer Unallocated Total December 31, 2017 Ending ALLL related to loans collectively evaluated for impairment $ 3,604 $ 2,106 $ 6,316 $ 674 $ 1,025 $ 535 $ 276 $ 718 $ 15,254 Ending ALLL related to loans individually evaluated for impairment 50 188 159 7 6 1 102 — 513 Ending ALLL related to purchased credit-impaired loans — — — — — — — — — Ending balance $ 3,654 $ 2,294 $ 6,475 $ 681 $ 1,031 $ 536 $ 378 $ 718 $ 15,767 Recorded Investment: Collectively evaluated for impairment $ 233,605 $ 292,798 $ 820,023 $ 60,859 $ 131,620 $ 94,378 $ 26,689 $ — $ 1,659,972 Individually evaluated for impairment 2,165 6,999 2,171 2,969 753 1,148 721 — 16,926 Purchased credit-impaired 65 1,166 790 — 94 — — — 2,115 Total $ 235,835 $ 300,963 $ 822,984 $ 63,828 $ 132,467 $ 95,526 $ 27,410 $ — $ 1,679,013 Ratio of allowance for loan losses to total loans 1.55 % 0.76 % 0.79 % 1.07 % 0.78 % 0.56 % 1.38 % NM 0.94 % Allowance for loan losses to non-accrual loans NM NM NM NM 254 % NM NM NM 3,883 % NM - Not Meaningful
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period	The following table reflects the unpaid principal balance and related carrying value of PCI loans. PCI Loans March 31, 2018 December 31, 2017 (in thousands) Unpaid Principal Balance Carrying Value Unpaid Principal Balance Carrying Value Commercial and industrial $ 141 $ 52 $ 276 $ 65 Commercial real estate, owner occupied 1,284 1,194 1,297 1,166 Commercial real estate, investor 1,056 797 1,064 790 Home equity 226 92 231 94 Total purchased credit-impaired loans $ 2,707 $ 2,135 $ 2,868 $ 2,115
Accretable Yield Activity	The activities in the accretable yield, or income expected to be earned over the remaining lives of the PCI loans were as follows: Accretable Yield Three months ended (in thousands) March 31, 2018 March 31, 2017 Balance at beginning of period $ 1,254 $ 1,476 Accretion (112 ) (90 ) Balance at end of period $ 1,142 $ 1,386

Borrowings (Tables)

Borrowings (Tables)	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	The following table summarizes the contractual terms of the subordinated debentures due to the Trusts as of March 31, 2018 : (in thousands) Subordinated debentures due to NorCal Community Bancorp Trust I on October 7, 2033 with interest payable quarterly, based on 3-month LIBOR plus 3.05%, repricing quarterly (4.77% as of March 31, 2018), redeemable, in whole or in part, on any interest payment date $ 4,124 Subordinated debentures due to NorCal Community Bancorp Trust II on March 15, 2036 with interest payable quarterly, based on 3-month LIBOR plus 1.40%, repricing quarterly (3.52% as of March 31, 2018), redeemable, in whole or in part, on any interest payment date 4,124 Total $ 8,248

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Dividends Declared	The following table summarizes cash dividends paid to common shareholders, recorded as a reduction of retained earnings. Three months ended (in thousands, except per share data) March 31, 2018 March 31, 2017 Cash dividends to common stockholders $ 2,015 $ 1,655 Cash dividends per common share $ 0.29 $ 0.27

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Undrawn Loan Commitments and Standby Letters of Credit	The contractual amount of undrawn loan commitments and standby letters of credit not reflected on the consolidated statements of condition are as follows: (in thousands) March 31, 2018 December 31, 2017 Commercial lines of credit $ 226,816 $ 224,370 Revolving home equity lines 187,405 177,678 Undisbursed construction loans 24,315 35,322 Personal and other lines of credit 12,769 11,758 Standby letters of credit 2,539 4,074 Total commitments and standby letters of credit $ 453,844 $ 453,202
Schedule of Future Minimum Rental Payments for Operating Leases	At March 31, 2018 , the approximate minimum future commitments payable under non-cancelable contracts for leased premises are as follows: (in thousands) 2018 2019 2020 2021 2022 Thereafter Total Operating leases 1 $ 3,330 $ 4,198 $ 3,758 $ 2,138 $ 1,330 $ 2,904 $ 17,658 1 Minimum payments have not been reduced by minimum sublease rentals of $25 thousand due in the future under non-cancelable subleases.

Derivative Financial Instrume26

Derivative Financial Instruments and Hedging Activities (Tables)	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	Information on our derivatives follows: Asset derivatives Liability derivatives (in thousands) March 31, 2018 December 31, 2017 March 31, 2018 December 31, 2017 Fair value hedges: Interest rate contracts notional amount $ 9,171 $ 4,019 $ 9,429 $ 14,810 Interest rate contracts fair value 1 $ 239 $ 74 $ 376 $ 740 Three months ended (in thousands) March 31, 2018 March 31, 2017 Increase in value of designated interest rate swaps due to LIBOR interest rate movements recognized in interest income $ 529 $ 111 Payment on interest rate swaps recorded in interest income $ (55 ) $ (98 ) Decrease in value of hedged loans recognized in interest income $ (576 ) $ (113 ) Decrease in value of yield maintenance agreement recognized against interest income $ (4 ) $ (4 ) Net loss on derivatives recognized against interest income 2 $ (106 ) $ (104 ) 1 See Note 3, Fair Value of Assets and Liabilities, for valuation methodology. 2 Includes hedge ineffectiveness loss of $51 thousand and $6 thousand for the quarters ended March 31, 2018 and March 31, 2017 , respectively. Changes in value of swaps were included in the assessment of hedge effectiveness. Hedge ineffectiveness is the measure of the extent to which the change in the fair value of the hedging instruments does not exactly offset the change in the fair value of the hedged items from period to period.
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance	Information on our derivatives follows: Asset derivatives Liability derivatives (in thousands) March 31, 2018 December 31, 2017 March 31, 2018 December 31, 2017 Fair value hedges: Interest rate contracts notional amount $ 9,171 $ 4,019 $ 9,429 $ 14,810 Interest rate contracts fair value 1 $ 239 $ 74 $ 376 $ 740 Three months ended (in thousands) March 31, 2018 March 31, 2017 Increase in value of designated interest rate swaps due to LIBOR interest rate movements recognized in interest income $ 529 $ 111 Payment on interest rate swaps recorded in interest income $ (55 ) $ (98 ) Decrease in value of hedged loans recognized in interest income $ (576 ) $ (113 ) Decrease in value of yield maintenance agreement recognized against interest income $ (4 ) $ (4 ) Net loss on derivatives recognized against interest income 2 $ (106 ) $ (104 ) 1 See Note 3, Fair Value of Assets and Liabilities, for valuation methodology. 2 Includes hedge ineffectiveness loss of $51 thousand and $6 thousand for the quarters ended March 31, 2018 and March 31, 2017 , respectively. Changes in value of swaps were included in the assessment of hedge effectiveness. Hedge ineffectiveness is the measure of the extent to which the change in the fair value of the hedging instruments does not exactly offset the change in the fair value of the hedged items from period to period.
Offsetting Assets	Information on financial instruments that are eligible for offset in the consolidated statements of condition follows: Offsetting of Financial Assets and Derivative Assets Gross Amounts Net Amounts of Gross Amounts Not Offset in Gross Amounts Offset in the Assets Presented the Statements of Condition of Recognized Statements of in the Statements Financial Cash Collateral ( in thousands) Assets 1 Condition of Condition 1 Instruments Received Net Amount March 31, 2018 Derivatives by Counterparty: Counterparty A $ 239 $ — $ 239 $ (239 ) $ — $ — December 31, 2017 Derivatives by Counterparty: Counterparty A $ 74 $ — $ 74 $ (74 ) $ — $ — 1 Amounts exclude accrued interest totaling $2 thousand and $1 thousand at March 31, 2018 and December 31, 2017 , respectively. Offsetting of Financial Liabilities and Derivative Liabilities Gross Amounts Net Amounts of Gross Amounts Not Offset in Gross Amounts Offset in the Liabilities Presented the Statements of Condition of Recognized Statements of in the Statements Financial Cash Collateral (in thousands) Liabilities 2 Condition of Condition 2 Instruments Pledged Net Amount March 31, 2018 Derivatives by Counterparty: Counterparty A $ 376 $ — $ 376 $ (239 ) $ (137 ) $ — December 31, 2017 Derivatives by Counterparty: Counterparty A $ 740 $ — $ 740 $ (74 ) $ (666 ) $ —
Offsetting Liabilities	Offsetting of Financial Liabilities and Derivative Liabilities Gross Amounts Net Amounts of Gross Amounts Not Offset in Gross Amounts Offset in the Liabilities Presented the Statements of Condition of Recognized Statements of in the Statements Financial Cash Collateral (in thousands) Liabilities 2 Condition of Condition 2 Instruments Pledged Net Amount March 31, 2018 Derivatives by Counterparty: Counterparty A $ 376 $ — $ 376 $ (239 ) $ (137 ) $ — December 31, 2017 Derivatives by Counterparty: Counterparty A $ 740 $ — $ 740 $ (74 ) $ (666 ) $ — 2 Amounts exclude accrued interest totaling $5 thousand and $8 thousand at March 31, 2018 and December 31, 2017 , respectively.

Acquisition (Tables)

Acquisition (Tables)	3 Months Ended
	Mar. 31, 2018
Business Combinations [Abstract]
Schedule Of Acquisition-Related Expenses	Bank of Marin Bancorp incurred acquisition-related expenses in the consolidated statements of comprehensive income for the three months ended March 31, 2018 as follows: (in thousands) Three months ended March 31, 2018 Data processing 1 $ 392 Professional services 95 Personnel severance 106 Other 22 Total $ 615 1 Primarily relates to Bank of Napa's core processing system contract termination and deconversion fees.

Basis of Presentation (Details)

Basis of Presentation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Weighted average basic shares outstanding (shares)	6,914	6,092
Potentially dilutive common shares related to:
Stock options (shares)	75	62
Unvested restricted stock awards (shares)	17	18
Weighted average diluted shares outstanding (shares)	7,006	6,172
Net income	$ 6,389	$ 4,548	$ 15,976
Basic EPS (usd per share)	$ 0.92	$ 0.75
Diluted EPS (usd per share)	$ 0.91	$ 0.74
Weighted average anti-dilutive shares not included in the calculation of diluted EPS (shares)	32	13

Recently Issued Accounting St29

Recently Issued Accounting Standards (Details) $ in Thousands	Mar. 31, 2018USD ($)
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Undiscounted operating lease obligations, off-balance sheet	$ 17,658

Fair Value of Assets and Liab30

Fair Value of Assets and Liabilities - Recorded on a Recurring Basis (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018USD ($)security	Dec. 31, 2017USD ($)security
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 423,882	$ 332,467
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of securities | security		0
SBA-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	33,538	$ 25,982
Unrealized loss on SBA-guaranteed security recorded as part of other comprehensive income	(2)
Debentures of government- sponsored agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	27,336	12,938
Privately-issued collateralized mortgage obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	1,390	1,431
Obligations of state and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	93,414	97,491
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 5,538	6,564
U.S. government agency obligation collateralized by loans guaranteed by SBA program | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized loss on SBA-guaranteed security recorded as part of other comprehensive income		2
U.S. government agency obligation collateralized by loans guaranteed by SBA program | Significant Unobservable Inputs (Level 3) | Available-for-sale Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of securities | security	1
Assets and liabilities at fair value measured on a recurring basis | Carrying Value | Interest rate contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial assets (interest rate contracts)	$ 239	74
Derivative financial liabilities (interest rate contracts)	376	740
Assets and liabilities at fair value measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Interest rate contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial assets (interest rate contracts)	0	0
Derivative financial liabilities (interest rate contracts)	0	0
Assets and liabilities at fair value measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Interest rate contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial assets (interest rate contracts)	239	74
Derivative financial liabilities (interest rate contracts)	376	740
Assets and liabilities at fair value measured on a recurring basis | Significant Unobservable Inputs (Level 3) | Interest rate contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial assets (interest rate contracts)	0	0
Derivative financial liabilities (interest rate contracts)	0	0
Assets and liabilities at fair value measured on a recurring basis | Mortgage-backed securities and collateralized mortgage obligations issued by U.S. government agencies | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	262,666	188,061
Assets and liabilities at fair value measured on a recurring basis | Mortgage-backed securities and collateralized mortgage obligations issued by U.S. government agencies | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Assets and liabilities at fair value measured on a recurring basis | Mortgage-backed securities and collateralized mortgage obligations issued by U.S. government agencies | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	262,666	188,061
Assets and liabilities at fair value measured on a recurring basis | Mortgage-backed securities and collateralized mortgage obligations issued by U.S. government agencies | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Assets and liabilities at fair value measured on a recurring basis | SBA-backed securities | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	33,538	25,982
Assets and liabilities at fair value measured on a recurring basis | SBA-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0
Assets and liabilities at fair value measured on a recurring basis | SBA-backed securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	33,373	25,817
Assets and liabilities at fair value measured on a recurring basis | SBA-backed securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	165	165
Assets and liabilities at fair value measured on a recurring basis | Debentures of government- sponsored agencies | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	27,336	12,938
Assets and liabilities at fair value measured on a recurring basis | Debentures of government- sponsored agencies | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Assets and liabilities at fair value measured on a recurring basis | Debentures of government- sponsored agencies | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	27,336	12,938
Assets and liabilities at fair value measured on a recurring basis | Debentures of government- sponsored agencies | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Assets and liabilities at fair value measured on a recurring basis | Privately-issued collateralized mortgage obligations | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	1,390	1,431
Assets and liabilities at fair value measured on a recurring basis | Privately-issued collateralized mortgage obligations | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Assets and liabilities at fair value measured on a recurring basis | Privately-issued collateralized mortgage obligations | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	1,390	1,431
Assets and liabilities at fair value measured on a recurring basis | Privately-issued collateralized mortgage obligations | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Assets and liabilities at fair value measured on a recurring basis | Obligations of state and political subdivisions | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	93,414	97,491
Assets and liabilities at fair value measured on a recurring basis | Obligations of state and political subdivisions | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Assets and liabilities at fair value measured on a recurring basis | Obligations of state and political subdivisions | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	93,414	97,491
Assets and liabilities at fair value measured on a recurring basis | Obligations of state and political subdivisions | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Assets and liabilities at fair value measured on a recurring basis | Corporate bonds | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	5,538	6,564
Assets and liabilities at fair value measured on a recurring basis | Corporate bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Assets and liabilities at fair value measured on a recurring basis | Corporate bonds | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	5,538	6,564
Assets and liabilities at fair value measured on a recurring basis | Corporate bonds | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 0	$ 0

Fair Value of Assets and Liab31

Fair Value of Assets and Liabilities - Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Investment securities held-to-maturity	$ 145,818	$ 151,032
Carrying Amounts | Level 1
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Cash and cash equivalents	159,347	203,545
Carrying Amounts | Level 2
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Investment securities held-to-maturity	149,013	151,032
Interest receivable	7,087	7,501
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Time deposits	145,942	160,116
Interest payable	172	191
Carrying Amounts | Level 3
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Loans, net	1,655,969	1,663,246
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Subordinated debentures	5,772	5,739
Fair Value | Level 1
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Cash and cash equivalents	159,347	203,545
Fair Value | Level 2
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Investment securities held-to-maturity	145,818	151,032
Interest receivable	7,087	7,501
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Time deposits	145,212	159,540
Interest payable	172	191
Fair Value | Level 3
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Loans, net	1,622,552	1,650,198
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Subordinated debentures	$ 6,820	$ 5,118

Investment Securities - Amortiz

Investment Securities - Amortized Cost and Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	$ 149,013	$ 151,032
Held to maturity, Fair Value	145,818	151,032
Held-to-maturity, Gross Unrealized Gains	291	619
Held-to-maturity, Gross Unrealized Losses	(3,486)	(619)
Available-for-sale, Amortized Cost	431,871	334,285
Available-for-sale, at fair value	423,882	332,467
Available-for-sale, Gross Unrealized Gains	239	574
Available-for-sale, Gross Unrealized Losses	(8,228)	(2,392)
Total investment securities, Amortized Cost	580,884	485,317
Total investment securities, Fair Value	569,700	483,499
Total investment securities, Gross Unrealized Gains	530	1,193
Total investment securities, Gross Unrealized Losses	(11,714)	(3,011)
MBS pass-through securities issued by FHLMC and FNMA
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Available-for-sale, Amortized Cost	93,915	65,559
Available-for-sale, at fair value	92,029	65,262
Available-for-sale, Gross Unrealized Gains	22	126
Available-for-sale, Gross Unrealized Losses	(1,908)	(423)
SBA-backed securities
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Available-for-sale, Amortized Cost	33,809	25,979
Available-for-sale, at fair value	33,538	25,982
Available-for-sale, Gross Unrealized Gains	8	58
Available-for-sale, Gross Unrealized Losses	(279)	(55)
CMOs issued by FNMA
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Available-for-sale, Amortized Cost	34,210	35,340
Available-for-sale, at fair value	33,613	35,125
Available-for-sale, Gross Unrealized Gains	9	33
Available-for-sale, Gross Unrealized Losses	(606)	(248)
CMOs issued by FHLMC
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Available-for-sale, Amortized Cost	123,007	70,514
Available-for-sale, at fair value	120,374	69,889
Available-for-sale, Gross Unrealized Gains	60	3
Available-for-sale, Gross Unrealized Losses	(2,693)	(628)
CMOs issued by GNMA
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Available-for-sale, Amortized Cost	17,173	17,953
Available-for-sale, at fair value	16,650	17,785
Available-for-sale, Gross Unrealized Gains	5	26
Available-for-sale, Gross Unrealized Losses	(528)	(194)
Debentures of government- sponsored agencies
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Available-for-sale, Amortized Cost	27,446	12,940
Available-for-sale, at fair value	27,336	12,938
Available-for-sale, Gross Unrealized Gains	6	3
Available-for-sale, Gross Unrealized Losses	(116)	(5)
Privately issued CMOs
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Available-for-sale, Amortized Cost	1,389	1,432
Available-for-sale, at fair value	1,390	1,431
Available-for-sale, Gross Unrealized Gains	3	1
Available-for-sale, Gross Unrealized Losses	(2)	(2)
Obligations of state and political subdivisions
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Available-for-sale, Amortized Cost	95,395	98,027
Available-for-sale, at fair value	93,414	97,491
Available-for-sale, Gross Unrealized Gains	99	298
Available-for-sale, Gross Unrealized Losses	(2,080)	(834)
Corporate bonds
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Available-for-sale, Amortized Cost	5,527	6,541
Available-for-sale, at fair value	5,538	6,564
Available-for-sale, Gross Unrealized Gains	27	26
Available-for-sale, Gross Unrealized Losses	(16)	(3)
Obligations of state and political subdivisions
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	19,599	19,646
Held to maturity, Fair Value	19,857	19,998
Held-to-maturity, Gross Unrealized Gains	278	383
Held-to-maturity, Gross Unrealized Losses	(20)	(31)
MBS pass-through securities issued by FHLMC and FNMA
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	97,222	100,376
Held to maturity, Fair Value	94,735	100,096
Held-to-maturity, Gross Unrealized Gains	12	234
Held-to-maturity, Gross Unrealized Losses	(2,499)	(514)
CMOs issued by FHLMC
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	32,192	31,010
Held to maturity, Fair Value	31,226	30,938
Held-to-maturity, Gross Unrealized Gains	1	2
Held-to-maturity, Gross Unrealized Losses	$ (967)	$ (74)

Investment Securities - Maturit

Investment Securities - Maturities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Held-to-maturity Securities, Amortized Cost
Within one year	$ 3,230	$ 2,151
After one but within five years	14,458	15,577
After five years through ten years	53,048	54,641
After ten years	78,277	78,663
Total	149,013	151,032
Held-to-maturity Securities, Fair Value
Within one year	3,256	2,172
After one but within five years	14,599	15,791
After five years through ten years	51,589	54,554
After ten years	76,374	78,515
Total	145,818	151,032
Available-for-sale Securities, Amortized Cost
Within one year	10,291	10,268
After one but within five years	77,606	71,576
After five years through ten years	225,526	129,723
After ten years	118,448	122,718
Total	431,871	334,285
Available-for-sale Securities, Fair Value
Within one year	10,281	10,272
After one but within five years	76,619	71,237
After five years through ten years	220,904	128,954
After ten years	116,078	122,004
Total	$ 423,882	$ 332,467

Investment Securities - Pledged

Investment Securities - Pledged and Transferred Securities (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities transferred from available-for-sale to held-to-maturity	$ 0	$ 128,965	$ 129,000
Unrealized pre-tax loss from transfer of available-for-sale securities to held-to-maturity			3,000
Amortization of net unrealized loss on available-for-sale securities transferred to held-to-maturity	136	$ 41	41
Public Deposits
Financial Instruments Owned and Pledged as Collateral [Line Items]
Available-for-sale securities pledged as collateral	102,738		107,829
Trust Deposits
Financial Instruments Owned and Pledged as Collateral [Line Items]
Available-for-sale securities pledged as collateral	754		761
State of California
Financial Instruments Owned and Pledged as Collateral [Line Items]
Available-for-sale securities pledged as collateral	103,492		108,590
Internal checking account
Financial Instruments Owned and Pledged as Collateral [Line Items]
Available-for-sale securities pledged as collateral	$ 2,018		$ 2,026

Investment Securities - Unreali

Investment Securities - Unrealized Loss Positions (Details) $ in Thousands	Mar. 31, 2018USD ($)security	Dec. 31, 2017USD ($)security
Investments, Debt and Equity Securities [Abstract]
Number of investment securities other-than-temporarily impaired | security	0
Number of investment securities in unrealized loss position | security	258	198
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 continuous months	$ 42,777	$ 31,051
Greater than or equal to 12 continuous months	82,475	60,669
Total Securities in a loss position	125,252	91,720
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 continuous months	(1,076)	(205)
Greater than or equal to 12 continuous months	(2,410)	(414)
Held-to-maturity, Gross Unrealized Losses	(3,486)	(619)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale, less than 12 continuous months, Fair value	329,365	212,675
Available-for-sale, greater than 12 continuous months, Fair value	43,001	40,478
Available-for-sale, Total Securities in a loss position, Fair Value	372,366	253,153
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Available-for-sale, less than 12 continuous months, Unrealized loss	(6,339)	(1,465)
Available-for-sale, greater than 12 continuous months, Unrealized loss	(1,889)	(927)
Available-for-sale, Total Securities in a loss position, Unrealized loss	(8,228)	(2,392)
Marketable Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Marketable securities, less than 12 continuous months, Fair value	372,142	243,726
Marketable securities, greater than 12 continuous months, Fair value	125,476	101,147
Marketable securities, Total Securities in a loss position, Fair value	497,618	344,873
Marketable Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Marketable securities, less than 12 continuous months, Unrealized loss	(7,415)	(1,670)
Marketable securities, greater than 12 continuous months, Unrealized loss	(4,299)	(1,341)
Marketable securities, Total Securities in a loss position, Unrealized loss	$ (11,714)	(3,011)
Number of investment securities in unrealized loss position longer than 12 months | security	61
Number of investment securities in unrealized loss position less than 12 months | security	197
Collateralized Mortgage Obligations [Member]
Marketable Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Number of investment securities in unrealized loss position less than 12 months | security	43
MBS pass-through securities issued by FHLMC and FNMA
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale, less than 12 continuous months, Fair value	$ 71,449	32,189
Available-for-sale, greater than 12 continuous months, Fair value	18,895	15,325
Available-for-sale, Total Securities in a loss position, Fair Value	90,344	47,514
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Available-for-sale, less than 12 continuous months, Unrealized loss	(1,314)	(121)
Available-for-sale, greater than 12 continuous months, Unrealized loss	(594)	(302)
Available-for-sale, Total Securities in a loss position, Unrealized loss	$ (1,908)	(423)
Marketable Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Number of investment securities in unrealized loss position longer than 12 months | security	21
Number of investment securities in unrealized loss position less than 12 months | security	34
SBA-backed securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale, less than 12 continuous months, Fair value	$ 24,816	11,028
Available-for-sale, greater than 12 continuous months, Fair value	165	165
Available-for-sale, Total Securities in a loss position, Fair Value	24,981	11,193
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Available-for-sale, less than 12 continuous months, Unrealized loss	(277)	(53)
Available-for-sale, greater than 12 continuous months, Unrealized loss	(2)	(2)
Available-for-sale, Total Securities in a loss position, Unrealized loss	$ (279)	(55)
Marketable Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Number of investment securities in unrealized loss position longer than 12 months | security	1
Number of investment securities in unrealized loss position less than 12 months | security	7
CMOs issued by FNMA
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale, less than 12 continuous months, Fair value	$ 28,289	26,401
Available-for-sale, greater than 12 continuous months, Fair value	5,061	5,440
Available-for-sale, Total Securities in a loss position, Fair Value	33,350	31,841
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Available-for-sale, less than 12 continuous months, Unrealized loss	(473)	(171)
Available-for-sale, greater than 12 continuous months, Unrealized loss	(133)	(77)
Available-for-sale, Total Securities in a loss position, Unrealized loss	$ (606)	(248)
Marketable Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Number of investment securities in unrealized loss position longer than 12 months | security	3
CMOs issued by FHLMC
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale, less than 12 continuous months, Fair value	$ 107,801	69,276
Available-for-sale, greater than 12 continuous months, Fair value	0	0
Available-for-sale, Total Securities in a loss position, Fair Value	107,801	69,276
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Available-for-sale, less than 12 continuous months, Unrealized loss	(2,693)	(628)
Available-for-sale, greater than 12 continuous months, Unrealized loss	0	0
Available-for-sale, Total Securities in a loss position, Unrealized loss	$ (2,693)	(628)
Marketable Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Number of investment securities in unrealized loss position longer than 12 months | security	4
CMOs issued by GNMA
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale, less than 12 continuous months, Fair value	$ 15,955	14,230
Available-for-sale, greater than 12 continuous months, Fair value	0	0
Available-for-sale, Total Securities in a loss position, Fair Value	15,955	14,230
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Available-for-sale, less than 12 continuous months, Unrealized loss	(528)	(194)
Available-for-sale, greater than 12 continuous months, Unrealized loss	0	0
Available-for-sale, Total Securities in a loss position, Unrealized loss	(528)	(194)
Debentures of government- sponsored agencies
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale, less than 12 continuous months, Fair value	12,330	2,984
Available-for-sale, greater than 12 continuous months, Fair value	0	0
Available-for-sale, Total Securities in a loss position, Fair Value	12,330	2,984
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Available-for-sale, less than 12 continuous months, Unrealized loss	(116)	(5)
Available-for-sale, greater than 12 continuous months, Unrealized loss	0	0
Available-for-sale, Total Securities in a loss position, Unrealized loss	$ (116)	(5)
Marketable Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Number of investment securities in unrealized loss position less than 12 months | security	5
Privately issued CMOs
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale, less than 12 continuous months, Fair value	$ 862	1,310
Available-for-sale, greater than 12 continuous months, Fair value	0	0
Available-for-sale, Total Securities in a loss position, Fair Value	862	1,310
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Available-for-sale, less than 12 continuous months, Unrealized loss	(2)	(2)
Available-for-sale, greater than 12 continuous months, Unrealized loss	0	0
Available-for-sale, Total Securities in a loss position, Unrealized loss	$ (2)	(2)
Marketable Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Number of investment securities in unrealized loss position less than 12 months | security	1
Obligations of state and political subdivisions
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale, less than 12 continuous months, Fair value	$ 63,831	52,197
Available-for-sale, greater than 12 continuous months, Fair value	18,880	19,548
Available-for-sale, Total Securities in a loss position, Fair Value	82,711	71,745
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Available-for-sale, less than 12 continuous months, Unrealized loss	(920)	(288)
Available-for-sale, greater than 12 continuous months, Unrealized loss	(1,160)	(546)
Available-for-sale, Total Securities in a loss position, Unrealized loss	$ (2,080)	(834)
Marketable Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Number of investment securities in unrealized loss position longer than 12 months | security	32
Number of investment securities in unrealized loss position less than 12 months | security	101
Corporate bonds
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale, less than 12 continuous months, Fair value	$ 4,032	3,060
Available-for-sale, greater than 12 continuous months, Fair value	0	0
Available-for-sale, Total Securities in a loss position, Fair Value	4,032	3,060
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Available-for-sale, less than 12 continuous months, Unrealized loss	(16)	(3)
Available-for-sale, greater than 12 continuous months, Unrealized loss	0	0
Available-for-sale, Total Securities in a loss position, Unrealized loss	$ (16)	(3)
Marketable Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Number of investment securities in unrealized loss position less than 12 months | security	6
Obligations of state and political subdivisions
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 continuous months	$ 3,636	3,648
Greater than or equal to 12 continuous months	0	0
Total Securities in a loss position	3,636	3,648
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 continuous months	(20)	(31)
Greater than or equal to 12 continuous months	0	0
Held-to-maturity, Gross Unrealized Losses	(20)	(31)
MBS pass-through securities issued by FHLMC and FNMA
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 continuous months	22,570	16,337
Greater than or equal to 12 continuous months	69,808	46,845
Total Securities in a loss position	92,378	63,182
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 continuous months	(611)	(143)
Greater than or equal to 12 continuous months	(1,888)	(371)
Held-to-maturity, Gross Unrealized Losses	(2,499)	(514)
CMOs issued by FHLMC
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 continuous months	16,571	11,066
Greater than or equal to 12 continuous months	12,667	13,824
Total Securities in a loss position	29,238	24,890
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 continuous months	(445)	(31)
Greater than or equal to 12 continuous months	(522)	(43)
Held-to-maturity, Gross Unrealized Losses	$ (967)	$ (74)

Investment Securities - Non-Mar

Investment Securities - Non-Marketable Securities (Details)	3 Months Ended
	Mar. 31, 2018USD ($)$ / sharesshares	Apr. 26, 2018	Dec. 31, 2017USD ($)
Schedule of Cost-method Investments [Line Items]
Federal Home Loan Bank stock, par value (usd per share) | $ / shares	$ 100
Investments in low income housing tax credit funds	$ 5,000,000		$ 2,100,000
Low income housing tax credits and other tax benefits	110,000
Low income housing amortization expense	94,000
Unfunded commitments for low income housing tax credit funds	$ 3,200,000
Visa Inc. | Visa Inc. Class B common stock
Schedule of Cost-method Investments [Line Items]
Conversion rate on common stock	1.6483
Visa Inc. Class B common stock
Schedule of Cost-method Investments [Line Items]
Number of shares of securities carried at cost | shares	16,939
Carrying value of securities carried at cost	$ 0
Fair value of Class B common stock	3,300,000		3,200,000
Subsequent event
Schedule of Cost-method Investments [Line Items]
Federal Home Loan Bank, dividend rate percentage		7.00%
Other assets
Schedule of Cost-method Investments [Line Items]
Federal Home Loan Bank stock	$ 11,100,000		$ 11,100,000

Loans and Allowance for Loan 37

Loans and Allowance for Loan Losses - Outstanding and Aging Analysis (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2018USD ($)loan	Dec. 31, 2017USD ($)loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	$ 389,000	$ 2,331,000
Current	1,671,351,000	1,676,682,000
Total loans	1,671,740,000	1,679,013,000
Non-accrual	$ 392,000	$ 406,000
Number of purchase credit impaired (PCI) loans with unpaid balances | loan	1	3
Unpaid balances on purchase credit impaired (PCI) loans	$ 11,000	$ 131,000
Purchased Credit Impaired (PCI) loans no longer accreting interest	0	0
Purchased Credit-impaired (PCI) loans accreting interest	2,100,000
Loans past due more than 90 days still accruing	0	0
Deferred loan fees	928,000	818,000
Unaccreted purchase discounts on non-PCI loans	1,100,000	1,200,000
30-59 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	385,000	684,000
60-89 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	4,000	1,340,000
90 days or more past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	307,000
Commercial loans | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	4,000	1,340,000
Current	231,676,000	234,495,000
Total loans	231,680,000	235,835,000
Non-accrual	0	0
Commercial loans | Commercial and industrial | 30-59 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	0
Commercial loans | Commercial and industrial | 60-89 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	4,000	1,340,000
Commercial loans | Commercial and industrial | 90 days or more past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	0
Commercial real estate loans | Commercial real estate, owner-occupied
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	0
Current	300,377,000	300,963,000
Total loans	300,377,000	300,963,000
Non-accrual	0	0
Commercial real estate loans | Commercial real estate, owner-occupied | 30-59 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	0
Commercial real estate loans | Commercial real estate, owner-occupied | 60-89 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	0
Commercial real estate loans | Commercial real estate, owner-occupied | 90 days or more past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	0
Commercial real estate loans | Commercial real estate, investor
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	0
Current	828,945,000	822,984,000
Total loans	828,945,000	822,984,000
Non-accrual	0	0
Commercial real estate loans | Commercial real estate, investor | 30-59 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	0
Commercial real estate loans | Commercial real estate, investor | 60-89 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	0
Commercial real estate loans | Commercial real estate, investor | 90 days or more past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	0
Commercial real estate loans | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	0
Current	64,978,000	63,828,000
Total loans	64,978,000	63,828,000
Non-accrual	0	0
Commercial real estate loans | Construction | 30-59 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	0
Commercial real estate loans | Construction | 60-89 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	0
Commercial real estate loans | Construction | 90 days or more past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	0
Residential loans | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	385,000	406,000
Current	124,314,000	132,061,000
Total loans	124,699,000	132,467,000
Non-accrual	392,000	406,000
Residential loans | Home equity | 30-59 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	385,000	99,000
Residential loans | Home equity | 60-89 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	0
Residential loans | Home equity | 90 days or more past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	307,000
Residential loans | Other residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	255,000
Current	95,621,000	95,271,000
Total loans	95,621,000	95,526,000
Non-accrual	0	0
Residential loans | Other residential | 30-59 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	255,000
Residential loans | Other residential | 60-89 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	0
Residential loans | Other residential | 90 days or more past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	0
Consumer loans | Installment and other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	330,000
Current	25,440,000	27,080,000
Total loans	25,440,000	27,410,000
Non-accrual	0	0
Consumer loans | Installment and other consumer | 30-59 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	330,000
Consumer loans | Installment and other consumer | 60-89 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	0
Consumer loans | Installment and other consumer | 90 days or more past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	$ 0	$ 0

Loans and Allowance for Loan 38

Loans and Allowance for Loan Losses - Credit Quality (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Total loans	$ 1,671,740	$ 1,679,013
Purchased credit-impaired
Financing Receivable, Recorded Investment [Line Items]
Purchased credit-impaired	2,135	2,115
Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,625,503	1,629,865
Pass | Purchased credit-impaired
Financing Receivable, Recorded Investment [Line Items]
Purchased credit-impaired	1,338	1,325
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	18,430	21,242
Special Mention | Purchased credit-impaired
Financing Receivable, Recorded Investment [Line Items]
Purchased credit-impaired	797	790
Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	27,807	27,906
Substandard | Purchased credit-impaired
Financing Receivable, Recorded Investment [Line Items]
Purchased credit-impaired	0	0
Commercial loans | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	231,628	235,770
Total loans	231,680	235,835
Commercial loans | Commercial and industrial | Purchased credit-impaired
Financing Receivable, Recorded Investment [Line Items]
Purchased credit-impaired	52	65
Commercial loans | Commercial and industrial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	213,676	214,636
Commercial loans | Commercial and industrial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	4,761	9,318
Commercial loans | Commercial and industrial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	13,191	11,816
Commercial real estate loans | Commercial real estate, owner-occupied
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	299,183	299,797
Total loans	300,377	300,963
Commercial real estate loans | Commercial real estate, owner-occupied | Purchased credit-impaired
Financing Receivable, Recorded Investment [Line Items]
Purchased credit-impaired	1,194	1,166
Commercial real estate loans | Commercial real estate, owner-occupied | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	279,899	281,104
Commercial real estate loans | Commercial real estate, owner-occupied | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	9,918	9,284
Commercial real estate loans | Commercial real estate, owner-occupied | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	9,366	9,409
Commercial real estate loans | Commercial real estate, investor
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	828,148	822,194
Total loans	828,945	822,984
Commercial real estate loans | Commercial real estate, investor | Purchased credit-impaired
Financing Receivable, Recorded Investment [Line Items]
Purchased credit-impaired	797	790
Commercial real estate loans | Commercial real estate, investor | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	824,867	818,570
Commercial real estate loans | Commercial real estate, investor | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	2,954	1,850
Commercial real estate loans | Commercial real estate, investor | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	327	1,774
Commercial real estate loans | Construction
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	64,978	63,828
Total loans	64,978	63,828
Commercial real estate loans | Construction | Purchased credit-impaired
Financing Receivable, Recorded Investment [Line Items]
Purchased credit-impaired	0	0
Commercial real estate loans | Construction | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	62,003	60,859
Commercial real estate loans | Construction | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	0	0
Commercial real estate loans | Construction | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	2,975	2,969
Residential loans | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	124,607	132,373
Total loans	124,699	132,467
Residential loans | Home equity | Purchased credit-impaired
Financing Receivable, Recorded Investment [Line Items]
Purchased credit-impaired	92	94
Residential loans | Home equity | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	122,760	130,558
Residential loans | Home equity | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	0	0
Residential loans | Home equity | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	1,847	1,815
Residential loans | Other residential
Financing Receivable, Recorded Investment [Line Items]
Total loans	95,621	95,526
Residential loans | Other residential | Purchased credit-impaired
Financing Receivable, Recorded Investment [Line Items]
Purchased credit-impaired	0	0
Residential loans | Other residential | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	95,621	95,526
Residential loans | Other residential | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Residential loans | Other residential | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Consumer loans | Installment and other consumer
Financing Receivable, Recorded Investment [Line Items]
Total loans	25,440	27,410
Consumer loans | Installment and other consumer | Purchased credit-impaired
Financing Receivable, Recorded Investment [Line Items]
Purchased credit-impaired	0	0
Consumer loans | Installment and other consumer | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	25,339	27,287
Consumer loans | Installment and other consumer | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Consumer loans | Installment and other consumer | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	$ 101	$ 123

Loans and Allowance for Loan 39

Loans and Allowance for Loan Losses - Troubled Debt Restructuring by Class (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2018USD ($)loan	Dec. 31, 2017USD ($)loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans removed from TDR designation | loan	1	0
Recorded investment of loans removed from TDR resignation	$ 150,000
Recorded investment in Troubled Debt Restructurings	16,155,000	$ 16,520,000
TDR loans on non-accrual status		0
Commercial loans | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in Troubled Debt Restructurings	2,267,000	2,165,000
Commercial real estate loans | Commercial real estate, owner-occupied
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in Troubled Debt Restructurings	7,007,000	6,999,000
Commercial real estate loans | Commercial real estate, investor
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in Troubled Debt Restructurings	1,854,000	2,171,000
Commercial real estate loans | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in Troubled Debt Restructurings	2,976,000	2,969,000
Residential loans | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in Troubled Debt Restructurings	347,000	347,000
Residential loans | Other residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in Troubled Debt Restructurings	992,000	1,148,000
Consumer loans | Installment and other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in Troubled Debt Restructurings	$ 712,000	$ 721,000

Loans and Allowance for Loan 40

Loans and Allowance for Loan Losses - Troubled Debt Restructuring Modifications (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)contractloan	Mar. 31, 2017USD ($)contractloan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts Modified | contract	0	1
Pre-Modification Outstanding Recorded Investment	$ 0	$ 50
Post-Modification Outstanding Recorded Investment	0	50
Post-Modification Outstanding Recorded Investment at Period End	$ 0	$ 50
Number of modified TDR loans that defaulted | loan	0	0

Loans and Allowance for Loan 41

Loans and Allowance for Loan Losses - Impaired and Related Allowance (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Recorded investment in impaired loans:
With no specific allowance recorded	$ 4,429,000		$ 4,445,000
With a specific allowance recorded	12,118,000		12,481,000
Total recorded investment in impaired loans	16,547,000		16,926,000
Unpaid principal balance of impaired loans	16,500,000		17,019,000
Specific allowance	354,000		513,000
Average recorded investment in impaired loans during the period	16,736,000	$ 18,384,000
Interest income recognized on impaired loans during the period ended	306,000	183,000
Interest income recognized on impaired loans during the period ended, cash basis	128,000	0
Outstanding commitments to extend credit on impaired loans	610,000		935,000
Commercial loans | Commercial and industrial
Recorded investment in impaired loans:
With no specific allowance recorded	307,000		309,000
With a specific allowance recorded	1,960,000		1,856,000
Total recorded investment in impaired loans	2,267,000		2,165,000
Unpaid principal balance of impaired loans	2,260,000		2,278,000
Specific allowance	35,000		50,000
Average recorded investment in impaired loans during the period	2,216,000	2,138,000
Interest income recognized on impaired loans during the period ended	155,000	23,000
Commercial real estate loans | Commercial real estate, owner-occupied
Recorded investment in impaired loans:
With no specific allowance recorded	0		0
With a specific allowance recorded	7,007,000		6,999,000
Total recorded investment in impaired loans	7,007,000		6,999,000
Unpaid principal balance of impaired loans	6,993,000		6,993,000
Specific allowance	162,000		188,000
Average recorded investment in impaired loans during the period	7,003,000	6,997,000
Interest income recognized on impaired loans during the period ended	66,000	66,000
Commercial real estate loans | Commercial real estate, investor
Recorded investment in impaired loans:
With no specific allowance recorded	0		0
With a specific allowance recorded	1,854,000		2,171,000
Total recorded investment in impaired loans	1,854,000		2,171,000
Unpaid principal balance of impaired loans	1,847,000		2,168,000
Specific allowance	48,000		159,000
Average recorded investment in impaired loans during the period	2,012,000	2,783,000
Interest income recognized on impaired loans during the period ended	22,000	23,000
Commercial real estate loans | Construction
Recorded investment in impaired loans:
With no specific allowance recorded	2,692,000		2,689,000
With a specific allowance recorded	284,000		280,000
Total recorded investment in impaired loans	2,976,000		2,969,000
Unpaid principal balance of impaired loans	2,962,000		2,963,000
Specific allowance	11,000		7,000
Average recorded investment in impaired loans during the period	2,972,000	3,243,000
Interest income recognized on impaired loans during the period ended	38,000	34,000
Residential loans | Home equity
Recorded investment in impaired loans:
With no specific allowance recorded	392,000		406,000
With a specific allowance recorded	347,000		347,000
Total recorded investment in impaired loans	739,000		753,000
Unpaid principal balance of impaired loans	736,000		750,000
Specific allowance	6,000		6,000
Average recorded investment in impaired loans during the period	746,000	713,000
Interest income recognized on impaired loans during the period ended	5,000	8,000
Residential loans | Other residential
Recorded investment in impaired loans:
With no specific allowance recorded	992,000		995,000
With a specific allowance recorded	0		153,000
Total recorded investment in impaired loans	992,000		1,148,000
Unpaid principal balance of impaired loans	991,000		1,147,000
Specific allowance	0		1,000
Average recorded investment in impaired loans during the period	1,070,000	1,571,000
Interest income recognized on impaired loans during the period ended	13,000	19,000
Consumer loans | Installment and other consumer
Recorded investment in impaired loans:
With no specific allowance recorded	46,000		46,000
With a specific allowance recorded	666,000		675,000
Total recorded investment in impaired loans	712,000		721,000
Unpaid principal balance of impaired loans	711,000		720,000
Specific allowance	92,000		$ 102,000
Average recorded investment in impaired loans during the period	717,000	939,000
Interest income recognized on impaired loans during the period ended	$ 7,000	$ 10,000

Loans and Allowance for Loan 42

Loans and Allowance for Loan Losses - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Allowance for loan losses:
Beginning balance	$ 15,767	$ 15,442
Provision for loan losses	0	0
Charge-offs	0	(287)
Recoveries	4	64
Ending balance	15,771	15,219
Ending ALLL related to loans collectively evaluated for impairment	15,417		$ 15,254
Ending ALLL related to loans individually evaluated for impairment	354		513
Ending ALLL	15,771		15,767
Collectively evaluated for impairment	1,653,058		1,659,972
Individually evaluated for impairment	16,547		16,926
Total loans	$ 1,671,740		$ 1,679,013
Ratio of allowance for loan losses to total loans	0.94%		0.94%
Allowance for loan losses to non-accrual loans	4023.00%		3883.00%
Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0
Purchased credit-impaired	2,135		2,115
Commercial loans | Commercial and industrial
Allowance for loan losses:
Beginning balance	3,654	3,248
Provision for loan losses	35	1,386
Charge-offs	0	(284)
Recoveries	4	63
Ending balance	3,693	4,413
Ending ALLL related to loans collectively evaluated for impairment	3,658		3,604
Ending ALLL related to loans individually evaluated for impairment	35		50
Ending ALLL	3,693		3,654
Collectively evaluated for impairment	229,361		233,605
Individually evaluated for impairment	2,267		2,165
Total loans	$ 231,680		$ 235,835
Ratio of allowance for loan losses to total loans	1.59%		1.55%
Commercial loans | Commercial and industrial | Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0
Purchased credit-impaired	52		65
Commercial real estate loans | Commercial real estate, owner-occupied
Allowance for loan losses:
Beginning balance	2,294	1,753
Provision for loan losses	(214)	239
Charge-offs	0	0
Recoveries	0	0
Ending balance	2,080	1,992
Ending ALLL related to loans collectively evaluated for impairment	1,918		2,106
Ending ALLL related to loans individually evaluated for impairment	162		188
Ending ALLL	2,080		2,294
Collectively evaluated for impairment	292,176		292,798
Individually evaluated for impairment	7,007		6,999
Total loans	$ 300,377		$ 300,963
Ratio of allowance for loan losses to total loans	0.69%		0.76%
Commercial real estate loans | Commercial real estate, owner-occupied | Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0
Purchased credit-impaired	1,194		1,166
Commercial real estate loans | Commercial real estate, investor
Allowance for loan losses:
Beginning balance	6,475	6,320
Provision for loan losses	(20)	(187)
Charge-offs	0	0
Recoveries	0	0
Ending balance	6,455	6,133
Ending ALLL related to loans collectively evaluated for impairment	6,407		6,316
Ending ALLL related to loans individually evaluated for impairment	48		159
Ending ALLL	6,455		6,475
Collectively evaluated for impairment	826,294		820,023
Individually evaluated for impairment	1,854		2,171
Total loans	$ 828,945		$ 822,984
Ratio of allowance for loan losses to total loans	0.78%		0.79%
Commercial real estate loans | Commercial real estate, investor | Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0
Purchased credit-impaired	797		790
Commercial real estate loans | Construction
Allowance for loan losses:
Beginning balance	681	781
Provision for loan losses	16	(235)
Charge-offs	0	0
Recoveries	0	0
Ending balance	697	546
Ending ALLL related to loans collectively evaluated for impairment	686		674
Ending ALLL related to loans individually evaluated for impairment	11		7
Ending ALLL	697		681
Collectively evaluated for impairment	62,002		60,859
Individually evaluated for impairment	2,976		2,969
Total loans	$ 64,978		$ 63,828
Ratio of allowance for loan losses to total loans	1.07%		1.07%
Commercial real estate loans | Construction | Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0
Purchased credit-impaired	0		0
Residential loans | Home equity
Allowance for loan losses:
Beginning balance	1,031	973
Provision for loan losses	(52)	17
Charge-offs	0	0
Recoveries	0	0
Ending balance	979	990
Ending ALLL related to loans collectively evaluated for impairment	973		1,025
Ending ALLL related to loans individually evaluated for impairment	6		6
Ending ALLL	979		1,031
Collectively evaluated for impairment	123,868		131,620
Individually evaluated for impairment	739		753
Total loans	$ 124,699		$ 132,467
Ratio of allowance for loan losses to total loans	0.79%		0.78%
Allowance for loan losses to non-accrual loans	250.00%		254.00%
Residential loans | Home equity | Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0
Purchased credit-impaired	92		94
Residential loans | Other residential
Allowance for loan losses:
Beginning balance	536	454
Provision for loan losses	7	(10)
Charge-offs	0	0
Recoveries	0	0
Ending balance	543	444
Ending ALLL related to loans collectively evaluated for impairment	543		535
Ending ALLL related to loans individually evaluated for impairment	0		1
Ending ALLL	543		536
Collectively evaluated for impairment	94,629		94,378
Individually evaluated for impairment	992		1,148
Total loans	$ 95,621		$ 95,526
Ratio of allowance for loan losses to total loans	0.57%		0.56%
Residential loans | Other residential | Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0
Purchased credit-impaired	0		0
Consumer loans | Installment and other consumer
Allowance for loan losses:
Beginning balance	378	372
Provision for loan losses	(27)	(11)
Charge-offs	0	(3)
Recoveries	0	1
Ending balance	351	359
Ending ALLL related to loans collectively evaluated for impairment	259		276
Ending ALLL related to loans individually evaluated for impairment	92		102
Ending ALLL	351		378
Collectively evaluated for impairment	24,728		26,689
Individually evaluated for impairment	712		721
Total loans	$ 25,440		$ 27,410
Ratio of allowance for loan losses to total loans	1.38%		1.38%
Consumer loans | Installment and other consumer | Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0
Purchased credit-impaired	0		0
Unallocated
Allowance for loan losses:
Beginning balance	718	1,541
Provision for loan losses	255	(1,199)
Charge-offs	0	0
Recoveries	0	0
Ending balance	973	$ 342
Ending ALLL related to loans collectively evaluated for impairment	973		718
Ending ALLL related to loans individually evaluated for impairment	0		0
Ending ALLL	973		718
Collectively evaluated for impairment	0		0
Individually evaluated for impairment	0		0
Total loans	0		0
Unallocated | Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	0		0
Purchased credit-impaired	$ 0		$ 0

Loans and Allowance for Loan 43

Loans and Allowance for Loan Losses - Purchased Credit-Impaired (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
PCI Loans, Carrying Value [Abstract]
Unpaid Principal Balance	$ 2,707		$ 2,868
Carrying Value	2,135		2,115
Accretable Yield [Roll Forward]
Balance at beginning of period	1,254	$ 1,476
Accretion	(112)	(90)
Balance at end of period	1,142	$ 1,386
Commercial loans | Commercial and industrial
PCI Loans, Carrying Value [Abstract]
Unpaid Principal Balance	141		276
Carrying Value	52		65
Commercial real estate loans | Commercial real estate, owner-occupied
PCI Loans, Carrying Value [Abstract]
Unpaid Principal Balance	1,284		1,297
Carrying Value	1,194		1,166
Commercial real estate loans | Commercial real estate, investor
PCI Loans, Carrying Value [Abstract]
Unpaid Principal Balance	1,056		1,064
Carrying Value	797		790
Residential loans | Home equity
PCI Loans, Carrying Value [Abstract]
Unpaid Principal Balance	226		231
Carrying Value	$ 92		$ 94

Loans and Allowance for Loan 44

Loans and Allowance for Loan Losses - Pledged Loans (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Financial Instruments Owned and Pledged as Collateral [Line Items]
Residential loans pledged for FRB borrowings	$ 1,007.5	$ 887.9
Other residential
Financial Instruments Owned and Pledged as Collateral [Line Items]
Pledged residential loan portfolio to secure borrowing with FRB	$ 65.8	$ 67.6

Loans and Allowance for Loan 45

Loans and Allowance for Loan Losses - Related Party (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Related party loans	$ 11.3	$ 11.9
Directors, Officers, Principal Shareholders and Associates
Related Party Transaction [Line Items]
Undisbursed commitment to related parties	$ 8.8	$ 9.1

Borrowings - Lines of Credit (D

Borrowings - Lines of Credit (Details) - Line of credit - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Federal Funds Purchased
Line of Credit Facility [Line Items]
Amount of borrowings outstanding	$ 0	$ 0
Federal Home Loan Bank Borrowings
Line of Credit Facility [Line Items]
Lines of credit	617,000,000	538,900,000
Federal Home Loan Bank Overnight Borrowings
Line of Credit Facility [Line Items]
Amount of borrowings outstanding	0
Federal Reserve Line of Credit
Line of Credit Facility [Line Items]
Lines of credit	49,900,000	52,100,000
Amount of borrowings outstanding	0	0
Unsecured Debt | Federal Funds Purchased
Line of Credit Facility [Line Items]
Lines of credit	$ 100,400,000	$ 100,400,000

Borrowings - Subordinated Debt

Borrowings - Subordinated Debt (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)debenture	Mar. 31, 2017USD ($)
Debt Instrument [Line Items]
Amount guaranteed, on subordinated basis, distributions and other payments on trust preferred securities	$ 8,000
Accretion of discount on subordinated debentures	$ 33	$ 42
Subordinated debenture
Debt Instrument [Line Items]
Number of subordinated debentures acquired | debenture	2
Subordinated debentures	$ 4,950
Contractual value of subordinated debt	8,248
Accretion of discount on subordinated debentures	$ 33	$ 42
Debenture distribution deferral period (up to number of years)	5 years
Subordinated debenture | NorCal Community Bancorp Trust I
Debt Instrument [Line Items]
Contractual value of subordinated debt	$ 4,124
Effective interest rate	4.77%
Subordinated debenture | NorCal Community Bancorp Trust II
Debt Instrument [Line Items]
Contractual value of subordinated debt	$ 4,124
Effective interest rate	3.52%
LIBOR | Subordinated debenture | NorCal Community Bancorp Trust I
Debt Instrument [Line Items]
Basis spread on subordinated debentures	3.05%
LIBOR | Subordinated debenture | NorCal Community Bancorp Trust II
Debt Instrument [Line Items]
Basis spread on subordinated debentures	1.40%

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($)	Apr. 20, 2018	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Class of Stock [Line Items]
Cash dividends to common stockholders		$ 2,015,000	$ 1,655,000	$ 6,896,000
Cash dividends per common share (usd per share)		$ 0.29	$ 0.27
Shares withheld for tax withholding and exercise of options		19,606	4,715
Amount of shares withheld for tax withholding and exercise of options		$ 1,400,000	$ 324,000
Shares withheld for tax withholding and exercise of options, weighted average price (usd per share)		$ 70.36	$ 68.80
Performance-based stock awards
Class of Stock [Line Items]
Vesting period of performance-based stock awards		3 years
Performance-based stock awards | Minimum
Class of Stock [Line Items]
Vesting percentage of performance-based awards		0.00%
Performance-based stock awards | Maximum
Class of Stock [Line Items]
Vesting percentage of performance-based awards		200.00%
Subsequent event
Class of Stock [Line Items]
Dividends declared per common share (usd per share)	$ 0.31
Share Repurchase Program, amount approved to repurchase	$ 25,000,000
Retained Earnings
Class of Stock [Line Items]
Cash dividends to common stockholders		$ 2,015,000		$ 6,896,000
Reclassification from AOCI to retained earnings for stranded income tax effects		$ 638,000

Commitments and Contingencies49

Commitments and Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2012	Dec. 31, 2017
Operating Leases
2,018	$ 3,330
2,019	4,198
2,020	3,758
2,021	2,138
2,022	1,330
Thereafter	2,904
Total	17,658
Minimum payments due on minimum sublease rentals under non-cancelable subleases	25
Rent expense	1,000	$ 1,000
Visa Inc.
Litigation Matters
Settlement agreement amount			$ 4,000,000
Balance of escrow account for legal settlements	900,000
Visa Inc. | Pending due to reversal
Litigation Matters
Settlements reached by percentage of sales volume of merchants who opted out in Visa litigation, percent				51.00%
Loan commitments and standby letters of credit, unused
Loss Contingencies [Line Items]
Loan commitments and standby letters of credit, off-balance sheet	453,844			$ 453,202
Loan commitments and standby letters of credit, unused | Interest payable and other liabilities
Loss Contingencies [Line Items]
Allowance for off balance sheet commitments	958			958
Commercial lines of credit
Loss Contingencies [Line Items]
Loan commitments and standby letters of credit, off-balance sheet	226,816			224,370
Revolving home equity lines
Loss Contingencies [Line Items]
Loan commitments and standby letters of credit, off-balance sheet	187,405			177,678
Undisbursed construction loans
Loss Contingencies [Line Items]
Loan commitments and standby letters of credit, off-balance sheet	24,315			35,322
Personal and other lines of credit
Loss Contingencies [Line Items]
Loan commitments and standby letters of credit, off-balance sheet	12,769			11,758
Standby letters of credit
Loss Contingencies [Line Items]
Loan commitments and standby letters of credit, off-balance sheet	$ 2,539			$ 4,074

Derivative Financial Instrume50

Derivative Financial Instruments and Hedging Activities - Information on Derivatives (Details) - Fair value hedge $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)derivative	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)
Derivatives, Fair Value [Line Items]
Net hedge ineffectiveness gain (loss), derivatives	$ 51	$ 6
Interest income
Derivatives, Fair Value [Line Items]
Increase in value of designated interest rate swaps due to LIBOR interest rate movements recognized in interest income	529	111
Payment on interest rate swaps recorded in interest income	(55)	(98)
Decrease in value of hedged loans recognized in interest income	(576)	(113)
Decrease in value of yield maintenance agreement recognized against interest income	(4)	(4)
Net loss on derivatives recognized against interest income	(106)	$ (104)
Designated as hedging instrument
Derivatives, Fair Value [Line Items]
Accrued interest on swaps	$ 7		$ 8
Designated as hedging instrument | Interest rate swap
Derivatives, Fair Value [Line Items]
Number of derivative instruments | derivative	5
Designated as hedging instrument | Interest rate swap | Other assets
Derivatives, Fair Value [Line Items]
Interest rate contracts notional amount, Asset derivatives	$ 9,171		4,019
Designated as hedging instrument | Interest rate swap | Other liabilities
Derivatives, Fair Value [Line Items]
Interest rate contracts notional amount, Liability derivatives	9,429		14,810
Designated as hedging instrument | Interest rate contract | Other assets
Derivatives, Fair Value [Line Items]
Interest rate contracts fair value, Asset derivatives	239		74
Designated as hedging instrument | Interest rate contract | Other liabilities
Derivatives, Fair Value [Line Items]
Interest rate contracts fair value, Liability derivatives	$ 376		$ 740

Derivative Financial Instrume51

Derivative Financial Instruments and Hedging Activities - Offsetting of Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Interest rate swap | Other assets
Offsetting Assets [Line Items]
Accrued interest on derivative asset interest rate swaps	$ 2	$ 1
Counterparty A
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	239	74
Gross Amounts Offset in the Statements of Condition	0	0
Net Amounts of Assets Presented in the Statements of Condition	239	74
Gross Amounts Not Offset in the Statements of Condition, Financial Instruments	(239)	(74)
Gross Amounts Not Offset in the Statements of Condition, Cash Collateral Received	0	0
Net Amount	$ 0	$ 0

Derivative Financial Instrume52

Derivative Financial Instruments and Hedging Activities - Offsetting of Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Interest rate swap | Other liabilities
Offsetting Liabilities [Line Items]
Accrued interest on derivative liability interest swaps	$ 5	$ 8
Counterparty A
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	376	740
Gross Amounts Offset in the Statements of Condition	0	0
Net Amounts of Liabilities Presented in the Statements of Condition	376	740
Gross Amounts Not Offset in the Statements of Condition, Financial Instruments	(239)	(74)
Gross Amounts Not Offset in the Statements of Condition, Cash Collateral Pledged	(137)	(666)
Net Amount	$ 0	$ 0

Acquisition - Narrative (Detail

Acquisition - Narrative (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2018USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)	Nov. 21, 2017USD ($)branch
Business Acquisition [Line Items]
Goodwill	$ 30,140,000		$ 30,140,000
Amortization of core deposit intangible	230,000	$ 118,000
Goodwill impairment	0
Bank of Napa, N.A. (Napa)
Business Acquisition [Line Items]
Number of branch offices | branch				2
Loans acquired				$ 134,700,000
Deposits assumed				249,900,000
Investment securities acquired				$ 75,500,000
Shares received by Napa shareholders in acquisition per acquiree share				0.307
Goodwill				$ 23,700,000
Core deposits | Bank of Napa, N.A. (Napa)
Business Acquisition [Line Items]
Core deposit intangible asset			4,400,000
Amortization of core deposit intangible	$ 127,000		$ 56,000
Useful life of core deposit intangible asset	10 years

Acquisition - Acquisition Relat

Acquisition - Acquisition Related Expenses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Business Acquisition [Line Items]
Data processing	$ 1,381	$ 939
Professional services	1,299	522
Other	1,696	$ 1,593
Bank of Napa, N.A. (Napa)
Business Acquisition [Line Items]
Data processing	392
Professional services	95
Personnel severance	106
Other	22
Total	$ 615