Bank of Marin Bancorp (BMRC) 10-Q 6 Nov 18 2018 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 31, 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
Smaller Reporting Company	false
Emerging Growth Company	false
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		6,974,765

CONSOLIDATED STATEMENTS OF COND

CONSOLIDATED STATEMENTS OF CONDITION - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets
Cash and due from banks	$ 142,718	$ 203,545
Investment securities
Held-to-maturity, at amortized cost	164,222	151,032
Available-for-sale, at fair value	405,571	332,467
Total investment securities	569,793	483,499
Loans, net of allowance for loan losses of $15,817 and $15,767 at September 30, 2018 and December 31, 2017, respectively	1,713,054	1,663,246
Bank premises and equipment, net	7,602	8,612
Goodwill	30,140	30,140
Core deposit intangible	5,802	6,492
Interest receivable and other assets	76,606	72,620
Total assets	2,545,715	2,468,154
Deposits
Non-interest bearing	1,109,909	1,014,103
Interest bearing
Transaction accounts	138,838	169,195
Savings accounts	178,171	178,473
Money market accounts	659,788	626,783
Time accounts	126,140	160,116
Total deposits	2,212,846	2,148,670
Subordinated debentures	5,831	5,739
Interest payable and other liabilities	18,435	16,720
Total liabilities	2,237,112	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 - 6,982,179 and 6,921,542 at September 30, 2018 and December 31, 2017, respectively	145,498	143,967
Retained earnings	172,723	155,544
Accumulated other comprehensive loss, net of taxes	(9,618)	(2,486)
Total stockholders' equity	308,603	297,025
Total liabilities and stockholders' equity	$ 2,545,715	$ 2,468,154

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF CONDITION (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Loans and Leases Receivable, Net Amount
Loans, allowance for loan losses	$ 15,817	$ 15,767
Stockholders' Equity
Preferred stock, authorized (in shares)	5,000,000	5,000,000
Preferred stock, issued (in shares)	0	0
Common stock, authorized (in shares)	15,000,000	15,000,000
Common stock, issued (in shares)	6,982,179	6,921,542
Common stock, outstanding (in shares)	6,982,179	6,921,542

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest income
Interest and fees on loans	$ 20,284	$ 16,738	$ 58,795	$ 49,010
Interest on investment securities
Securities of U.S. government agencies	2,953	1,525	8,288	4,577
Obligations of state and political subdivisions	546	511	1,788	1,632
Corporate debt securities and other	25	31	104	104
Interest on Federal funds sold and due from banks	400	406	1,088	623
Total interest income	24,208	19,211	70,063	55,946
Interest expense
Interest on interest-bearing transaction accounts	58	24	158	74
Interest on savings accounts	18	17	54	48
Interest on money market accounts	337	133	789	360
Interest on time accounts	130	138	426	423
Interest on Federal Home Loan Bank (FHLB) and other borrowings	1	0	2	0
Interest on subordinated debentures	125	111	362	328
Total interest expense	669	423	1,791	1,233
Net interest income	23,539	18,788	68,272	54,713
Provision for loan losses	0	0	0	0
Net interest income after provision for loan losses	23,539	18,788	68,272	54,713
Non-interest income
Merchant interchange fees, net	99	88	297	296
Earnings on bank-owned life insurance	227	209	685	628
Dividends on FHLB stock	194	177	582	585
(Losses) gains on investment securities, net	(90)	0	(79)	10
Other income	439	225	1,173	729
Total non-interest income	2,236	2,066	6,716	6,277
Non-interest expense
Salaries and related benefits	8,069	7,344	25,402	22,106
Occupancy and equipment	1,444	1,364	4,462	4,063
Depreciation and amortization	532	489	1,625	1,433
Federal Deposit Insurance Corporation insurance	186	167	568	490
Data processing	950	946	3,354	2,848
Professional services	727	801	2,836	1,845
Directors' expense	173	175	530	557
Information technology	262	179	795	563
Provision for losses on off-balance sheet commitments	0	100	0	57
Other expense	1,628	1,471	4,989	4,716
Total non-interest expense	13,971	13,036	44,561	38,678
Income before provision for income taxes	11,804	7,818	30,427	22,312
Provision for income taxes	3,124	2,686	7,467	7,446
Net income	$ 8,680	$ 5,132	$ 22,960	$ 14,866
Net income per common share:
Basic (usd per share)	$ 1.25	$ 0.84	$ 3.31	$ 2.43
Diluted (usd per share)	$ 1.23	$ 0.83	$ 3.27	$ 2.41
Weighted average shares:
Basic (shares)	6,950	6,123	6,936	6,109
Diluted (shares)	7,055	6,191	7,031	6,179
Comprehensive income:
Net income	$ 8,680	$ 5,132	$ 22,960	$ 14,866
Other comprehensive (loss) income
Change in net unrealized gain or loss on available-for-sale securities	(2,120)	(362)	(9,421)	6,309
Reclassification adjustment for losses (gains) on available-for-sale securities in net income	90	0	79	(10)
Net unrealized loss on securities transferred from available-for-sale to held-to-maturity	0	0	(278)	(3,036)
Amortization of net unrealized losses on securities transferred from available-for-sale to held-to-maturity	128	135	396	299
Subtotal	(1,902)	(227)	(9,224)	3,562
Deferred tax (benefit) expense	(562)	(96)	(2,730)	1,499
Other comprehensive (loss) income, net of tax	(1,340)	(131)	(6,494)	2,063
Comprehensive income	7,340	5,001	16,466	16,929
Deposit Account
Non-interest income
Charges and Fees	475	438	1,407	1,337
Fiduciary and Trust
Non-interest income
Charges and Fees	490	539	1,493	1,546
Debit Card
Non-interest income
Charges and Fees	$ 402	$ 390	$ 1,158	$ 1,146

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	14,866		14,866
Other comprehensive income (loss)	2,063			2,063
Stock options exercised, net of shares surrendered for cashless exercises and tax withholdings (in shares)		8,786
Stock options exercised, net of shares surrendered for cashless exercises and tax withholdings	28	$ 28
Stock issued under employee stock purchase plan (in shares)		280
Stock issued under employee stock purchase plan	17	$ 17
Stock issued under employee stock ownership plan (ESOP) (in shares)		21,732
Stock issued under employee stock ownership plan (ESOP)	1,335	$ 1,335
Stock-based compensation - stock options	423	423
Stock-based compensation - restricted stock	634	$ 634
Cash dividends paid on common stock ($0.29 per share)	(5,103)		(5,103)
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
Restricted stock granted (in shares)		14,230
Restricted stock granted	0
Balance (in shares) at Sep. 30, 2017		6,175,751
Balance at Sep. 30, 2017	245,049	$ 90,052	156,227	(1,230)
Balance (in shares) at Jun. 30, 2017		6,160,952
Balance at Jun. 30, 2017	240,733	$ 88,949	152,883	(1,099)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	5,132		5,132
Other comprehensive income (loss)	(131)			(131)
Stock options exercised, net of shares surrendered for cashless exercises and tax withholdings (in shares)		2,893
Stock options exercised, net of shares surrendered for cashless exercises and tax withholdings	0	$ 0
Stock issued under employee stock ownership plan (ESOP) (in shares)		10,000
Stock issued under employee stock ownership plan (ESOP)	637	$ 637
Stock-based compensation - stock options	141	141
Stock-based compensation - restricted stock	206	$ 206
Cash dividends paid on common stock ($0.29 per share)	(1,788)		(1,788)
Stock purchased by directors under director stock plan (in shares)		216
Stock purchased by directors under director stock plan	13	$ 13
Stock issued in payment of director fees (in shares)		1,690
Stock issued in payment of director fees	106	$ 106
Balance (in shares) at Sep. 30, 2017		6,175,751
Balance at Sep. 30, 2017	$ 245,049	$ 90,052	156,227	(1,230)
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	22,960		22,960
Other comprehensive income (loss)	(6,494)			(6,494)
Stock options exercised, net of shares surrendered for cashless exercises and tax withholdings (in shares)		51,826
Stock options exercised, net of shares surrendered for cashless exercises and tax withholdings	534	$ 534
Stock issued under employee stock purchase plan (in shares)		386
Stock issued under employee stock purchase plan	28	$ 28
Stock issued under employee stock ownership plan (ESOP) (in shares)		11,300
Stock issued under employee stock ownership plan (ESOP)	898	$ 898
Stock-based compensation - stock options	566	566
Stock-based compensation - restricted stock	848	$ 848
Cash dividends paid on common stock ($0.29 per share)	(6,419)		(6,419)
Stock purchased by directors under director stock plan (in shares)		499
Stock purchased by directors under director stock plan	37	$ 37
Stock issued in payment of director fees (in shares)		2,735
Stock issued in payment of director fees	204	$ 204
Stock repurchased, net of commissions (in shares)		(17,943)
Stock repurchased, net of commissions	(1,539)	$ (1,539)
Reclassification of stranded tax effects in AOCI	0		638	(638)
Restricted stock granted (in shares)		18,520
Restricted stock granted	0
Restricted stock surrendered for tax withholdings upon vesting (in shares)		(658)
Restricted stock surrendered for tax withholdings upon vesting	$ (45)	$ (45)
Restricted stock forfeited / cancelled (in shares)		(6,028)
Restricted stock forfeited / cancelled		$ 0
Balance (in shares) at Sep. 30, 2018	6,982,179	6,982,179
Balance at Sep. 30, 2018	$ 308,603	$ 145,498	172,723	(9,618)
Balance (in shares) at Jun. 30, 2018		6,991,821
Balance at Jun. 30, 2018	304,198	$ 146,195	166,281	(8,278)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	8,680		8,680
Other comprehensive income (loss)	(1,340)			(1,340)
Stock options exercised, net of shares surrendered for cashless exercises and tax withholdings (in shares)		1,751
Stock options exercised, net of shares surrendered for cashless exercises and tax withholdings	0	$ 0
Stock issued under employee stock purchase plan (in shares)		121
Stock issued under employee stock purchase plan	9	$ 9
Stock issued under employee stock ownership plan (ESOP) (in shares)		3,400
Stock issued under employee stock ownership plan (ESOP)	297	$ 297
Stock-based compensation - stock options	124	124
Stock-based compensation - restricted stock	176	$ 176
Cash dividends paid on common stock ($0.29 per share)	(2,238)		(2,238)
Stock purchased by directors under director stock plan (in shares)		239
Stock purchased by directors under director stock plan	19	$ 19
Stock issued in payment of director fees (in shares)		1,392
Stock issued in payment of director fees	113	$ 113
Stock repurchased, net of commissions (in shares)		(16,545)
Stock repurchased, net of commissions	$ (1,435)	$ (1,435)
Balance (in shares) at Sep. 30, 2018	6,982,179	6,982,179
Balance at Sep. 30, 2018	$ 308,603	$ 145,498	$ 172,723	$ (9,618)

CONSOLIDATED STATEMENTS OF CH_2

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Stockholders' Equity [Abstract]
Common Stock, Dividends, Per Share, Cash Paid	$ 0.32	$ 0.29	$ 0.92	$ 0.83

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Cash Flows from Operating Activities:
Net income	$ 8,680	$ 5,132	$ 22,960	$ 14,866
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for losses on off-balance sheet commitments	0	100	0	57
Noncash contribution expense to employee stock ownership plan			898	637
Noncash director compensation expense			219	170
Stock-based compensation expense			1,414	1,057
Amortization of core deposit intangible			690	354
Amortization of investment security premiums, net of accretion of discounts			2,172	2,204
Accretion of discount on acquired loans			(531)	(706)
Accretion of discount on subordinated debentures			92	117
Net change in deferred loan origination costs/fees			114	85
Loss (gain) on sale of investment securities	90	0	79	(10)
Depreciation and amortization	532	489	1,625	1,433
Gain on sale of repossessed assets			0	(1)
Earnings on bank-owned life insurance policies	(227)	(209)	(685)	(628)
Net change in operating assets and liabilities:
Deferred rent and other rent-related expenses			(278)	38
Interest receivable and other assets			2,780	421
Interest payable and other liabilities			(265)	350
Total adjustments			8,324	5,578
Net cash provided by operating activities			31,284	20,444
Cash Flows from Investing Activities:
Purchase of held-to-maturity securities			(1,988)	(4,496)
Purchase of available-for-sale securities			(174,617)	(51,130)
Proceeds from sale of available-for-sale securities	11,966	0	16,972	1,321
Proceeds from paydowns/maturities of held-to-maturity securities			15,947	22,352
Proceeds from paydowns/maturities of available-for-sale securities			45,917	37,126
Loans originated and principal collected, net			(50,315)	(37,370)
Purchase of premises and equipment			(615)	(1,143)
Proceeds from sale of other real estate owned or repossessed assets			0	170
Cash paid for low-income housing tax credit investment			(389)	(899)
Net cash used in investing activities			(149,088)	(34,069)
Cash Flows from Financing Activities:
Net increase in deposits			64,176	118,270
Proceeds from stock options exercised			585	88
Payment of tax withholdings for stock options exercised and vesting of restricted stock			(96)	(60)
Proceeds from stock issued under employee and director stock purchase plans			65	750
Stock repurchased, net of commissions			(1,334)	0
Cash dividends paid on common stock			(6,419)	(5,103)
Net cash provided by financing activities			56,977	113,945
Net (decrease) increase in cash and cash equivalents			(60,827)	100,320
Cash and cash equivalents at beginning of period			203,545	48,804	$ 48,804
Cash and cash equivalents at end of period	142,718	149,124	142,718	149,124	203,545
Supplemental disclosure of cash flow information:
Cash paid in interest			1,737	1,131
Cash paid in income taxes			4,900	6,815
Supplemental disclosure of noncash investing and financing activities:
Change in net unrealized gain or loss on available-for-sale securities			(9,421)	6,309
Securities transferred from available-for-sale to held-to-maturity			27,422	128,965	129,000
Amortization of net unrealized loss on available-for-sale securities transferred to held-to-maturity	$ 128	$ 135	396	299	$ 299
Stock issued to ESOP			898	637
Stock issued in payment of director fees			204	188
Subscription in low-income housing tax credit investment			3,000	0
Repurchase of stock not yet settled			$ 205	$ 0

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 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 accounts for its investment in the securities of the Trusts under the equity method, which is included in interest receivable and other assets in 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 the quarterly diluted EPS is computed using the average market prices during the three months included in the reporting period under the treasury stock method. 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 Nine months ended (in thousands, except per share data) September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Weighted average basic shares outstanding 6,950 6,123 6,936 6,109 Potentially dilutive common shares related to: Stock options 88 53 79 55 Unvested restricted stock awards 17 15 16 15 Weighted average diluted shares outstanding 7,055 6,191 7,031 6,179 Net income $ 8,680 $ 5,132 $ 22,960 $ 14,866 Basic EPS $ 1.25 $ 0.84 $ 3.31 $ 2.43 Diluted EPS $ 1.23 $ 0.83 $ 3.27 $ 2.41 Weighted average anti-dilutive shares not included in the calculation of diluted EPS — 23 1 19 On October 22, 2018, the Bancorp announced a 2 :1 stock split, payable on November 27, 2018, to shareholders of record at the close of business on November 9, 2018. Pro forma per share amounts are shown below to reflect the stock split, effective November 27, 2018. Three months ended Nine months ended (in thousands, except per share data) September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Basic EPS $ 0.62 $ 0.42 $ 1.66 $ 1.22 Diluted EPS $ 0.62 $ 0.41 $ 1.63 $ 1.20

Recently Adopted and Issued Acc

Recently Adopted and Issued Accounting Standards	9 Months Ended
	Sep. 30, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recently Adopted and 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 revenue recognition 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 we complete our performance obligation 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 the payment networks process transactions. 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. 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 for the periods presented. 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 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. We early adopted the amendments of this ASU in the second quarter of 2018, and elected to perform hedge effectiveness assessments using a qualitative approach instead of quantitative regression analysis going forward. The adoption of this ASU had an immaterial impact to our financial results. The amendments also require additional disclosures, which are included in Note 9, Derivative Financial Instruments and Hedging Activities. 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. In July 2018, the FASB issued two amendments to ASU 2016-02: ASU No. 2018-10, Codification Improvements to Topic 842, Leases , which provides various corrections and clarifications to ASU 2016-02; and ASU No. 2018-11, Leases (Topic 842): Targeted Improvements , which provides a new optional transition method and provides a lessor with practical expedients for separating lease and non-lease components of a lease. Early application of the amendments is permitted. We intend to adopt this ASU during the first quarter of 2019, as required. We completed an inventory of our lease agreements and selected a lease accounting software solution. We are in the process of abstracting and inputting lease-related data, developing policies and procedures, and designing related internal controls. As of September 30, 2018 , our undiscounted operating lease obligations that were off-balance sheet totaled $15.4 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 retained earnings, capital ratios, results of operations or return on average assets when adopted. 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 present financial assets at the net amount expected to be collected. 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 expected 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. The impact of this ASU on our financial condition and results of operations is not known at this time. In June 2018, the FASB issued ASU No. 2018-07, Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting . This update simplifies the accounting for share-based payment transactions for acquiring goods and services from nonemployees, applying some of the same requirements as employee share-based payment transactions. The ASU will not affect the accounting for share-based payment awards to nonemployee directors, which will continue to be treated as employee share-based transactions under the current standards. ASU 2018-07 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. We do not expect that the ASU will have a material impact on our financial condition or results of operations, as it is not our practice to issue stock-based awards to pay for goods and services from nonemployees, other than nonemployee directors. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement . The amendments in this ASU remove, modify and add disclosure requirements for the fair value reporting of assets and liabilities. The modifications and additions relate to Level 3 fair value measurements at the end of the reporting period. ASU 2018-13 is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted. Entities making this election are permitted to early adopt the eliminated or modified disclosure requirements and delay the adoption of all the new disclosure requirements until the ASU's effective date. We do not expect that the ASU will have a material impact on our financial condition or results of operations. In August 2018, the FASB issued ASU No. 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract . This standard aligns the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software, regardless of whether they convey a license to the hosted software. The accounting for the service element of a hosting arrangement that is a service contract is not affected by this ASU. The amendments are effective for public business entities for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. We do not expect that the ASU will have a material impact on our financial condition or results of operations. In October 2018, the FASB issued ASU No. 2018-16, Derivatives and Hedging (Topic 815): Inclusion of the Secured Overnight Financing Rate (SOFR) Overnight Index Swap (OIS) Rate as a Benchmark Interest Rate for Hedge Accounting Purposes . This update adds an alternative fifth permissible U.S. benchmark rate to be used for hedge accounting purposes. As we have already adopted the amendments in ASU 2017-12, which changed both the designation and measurement guidance for qualifying hedging relationships, the amendments in ASU 2018-16 are effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted in any interim period upon issuance of this ASU if an entity already has adopted ASU 2017-12. 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	9 Months Ended
	Sep. 30, 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. No such transfers occurred during the first nine months of 2018 or 2017. 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 September 30, 2018 Securities available-for-sale: Mortgage-backed securities and collateralized mortgage obligations issued by U.S. government agencies $ 246,220 $ — $ 246,220 $ — OCI SBA-backed securities 40,181 — 40,181 — OCI Debentures of government sponsored agencies 42,914 — 42,914 — OCI Privately-issued collateralized mortgage obligations 370 — 370 — OCI Obligations of state and political subdivisions 73,373 — 73,373 — OCI Corporate bonds 2,513 — 2,513 — OCI Derivative financial assets (interest rate contracts) 436 — 436 — NI Derivative financial liabilities (interest rate contracts) 163 — 163 — 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 reputable third-party service providers, 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 September 30, 2018 and December 31, 2017 , there were no Level 1 securities. As of December 31, 2017 , we had one Level 3 available-for-sale U.S. government agency obligation, which was paid off during the second quarter of 2018. 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 nine months ended September 30, 2018 or September 30, 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 us. 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 September 30, 2018 and December 31, 2017 , we did 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 September 30, 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. September 30, 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 $ 142,718 $ 142,718 Level 1 $ 203,545 $ 203,545 Level 1 Investment securities held-to-maturity 164,222 158,106 Level 2 151,032 151,032 Level 2 Loans, net 1,713,054 1,683,109 Level 3 1,663,246 1,650,198 Level 3 Interest receivable 7,366 7,366 Level 2 7,501 7,501 Level 2 Financial liabilities (recorded at amortized cost) Time deposits 126,140 124,796 Level 2 160,116 159,540 Level 2 Subordinated debentures 5,831 7,505 Level 3 5,739 5,118 Level 3 Interest payable 155 155 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 September 30, 2018 or December 31, 2017 .

Investment Securities

Investment Securities	9 Months Ended
	Sep. 30, 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"), Small Business Administration ("SBA"), or Government National Mortgage Association ("GNMA"), debentures issued by government-sponsored agencies such as FNMA, Federal Farm Credit Bureau, FHLB and FHLMC, and privately issued CMOs, as reflected in the following table. September 30, 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: Securities of U.S. government agencies: MBS pass-through securities issued by FHLMC and FNMA $ 91,237 $ 86,962 $ — $ (4,275 ) $ 100,376 $ 100,096 $ 234 $ (514 ) SBA-backed securities 8,723 8,489 — (234 ) — — — — CMOs issued by FNMA 11,646 11,254 — (392 ) — — — — CMOs issued by FHLMC 34,169 32,868 — (1,301 ) 31,010 30,938 2 (74 ) CMOs issued by GNMA 3,734 3,694 — (40 ) — — — — Obligations of state and political subdivisions 14,713 14,839 160 (34 ) 19,646 19,998 383 (31 ) Total held-to-maturity 164,222 158,106 160 (6,276 ) 151,032 151,032 619 (619 ) Available-for-sale: Securities of U.S. government agencies: MBS pass-through securities issued by FHLMC and FNMA 93,096 90,484 20 (2,632 ) 65,559 65,262 126 (423 ) SBA-backed securities 41,074 40,181 — (893 ) 25,979 25,982 58 (55 ) CMOs issued by FNMA 19,914 19,356 4 (562 ) 35,340 35,125 33 (248 ) CMOs issued by FHLMC 128,848 124,930 1 (3,919 ) 70,514 69,889 3 (628 ) CMOs issued by GNMA 11,938 11,450 — (488 ) 17,953 17,785 26 (194 ) Debentures of government- sponsored agencies 43,470 42,914 — (556 ) 12,940 12,938 3 (5 ) Privately issued CMOs 367 370 3 — 1,432 1,431 1 (2 ) Obligations of state and political subdivisions 75,519 73,373 41 (2,187 ) 98,027 97,491 298 (834 ) Corporate bonds 2,506 2,513 19 (12 ) 6,541 6,564 26 (3 ) Total available-for-sale 416,732 405,571 88 (11,249 ) 334,285 332,467 574 (2,392 ) Total investment securities $ 580,954 $ 563,677 $ 248 $ (17,525 ) $ 485,317 $ 483,499 $ 1,193 $ (3,011 ) The amortized cost a nd fair value of investment debt securities by contractual maturity at September 30, 2018 and December 31, 2017 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. September 30, 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 $ 2,677 $ 2,697 $ 10,111 $ 10,031 $ 2,151 $ 2,172 $ 10,268 $ 10,272 After one but within five years 12,476 12,438 69,230 67,972 15,577 15,791 71,576 71,237 After five years through ten years 60,422 58,041 239,939 232,532 54,641 54,554 129,723 128,954 After ten years 88,647 84,930 97,452 95,036 78,663 78,515 122,718 122,004 Total $ 164,222 $ 158,106 $ 416,732 $ 405,571 $ 151,032 $ 151,032 $ 334,285 $ 332,467 Sales of investment securities and gross gains and losses are shown in the following table. Three months ended Nine months ended (in thousands) September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Available-for-sale: Sales proceeds $ 11,966 $ — $ 16,972 $ 1,321 Gross realized gains — — 27 13 Gross realized losses (90 ) — (106 ) (3 ) Pledged investment securities are shown in the following table. (in thousands) September 30, 2018 December 31, 2017 Pledged to the State of California: Secure public deposits in compliance with the Local Agency Security Program $ 97,978 $ 107,829 Collateral for trust deposits 740 761 Total investment securities pledged to the State of California $ 98,718 $ 108,590 Collateral for Wealth Management and Trust Services checking account $ 2,005 $ 2,026 As part of our ongoing review of our investment securities portfolio, we reassessed the classification of certain securities issued by government sponsored agencies. During 2018 and 2017, we transferred $27.4 million and $129.0 million , respectively, of these securities from available-for-sale to held-to-maturity at fair value. We intend and have the ability to hold these securities to maturity. The net unrealized pre-tax loss of $278 thousand and $3.0 million , at the respective transfer dates, 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 $396 thousand and $299 thousand for the nine months ended September 30, 2018 and 2017, respectively. Other-Than-Temporarily Impaired ("OTTI") Debt Securities There were 253 and 198 investment securities in unrealized loss positions at September 30, 2018 and December 31, 2017 , respectively. Those securities are summarized and classified according to the duration of the loss period in the following tables: September 30, 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: MBS pass-through securities issued by FHLMC and FNMA $ 6,602 $ (225 ) $ 80,360 $ (4,050 ) $ 86,962 $ (4,275 ) SBA-backed securities 8,489 (234 ) — — $ 8,489 $ (234 ) CMOs issued by FNMA 11,254 (392 ) — — 11,254 (392 ) CMOs issued by FHLMC 11,430 (400 ) 21,438 (901 ) 32,868 (1,301 ) CMOs issued by GNMA — — 3,694 (40 ) 3,694 (40 ) Obligations of state and political subdivisions 3,792 (34 ) — — 3,792 (34 ) Total held-to-maturity 41,567 (1,285 ) 105,492 (4,991 ) 147,059 (6,276 ) Available-for-sale: MBS pass-through securities issued by FHLMC and FNMA 52,821 (1,804 ) 20,406 (828 ) 73,227 (2,632 ) SBA-backed securities 23,162 (893 ) — — 23,162 (893 ) CMOs issued by FNMA 13,230 (383 ) 5,905 (179 ) 19,135 (562 ) CMOs issued by FHLMC 87,017 (2,930 ) 29,702 (989 ) 116,719 (3,919 ) CMOs issued by GNMA 10,728 (485 ) 485 (3 ) 11,213 (488 ) Debentures of government- sponsored agencies 37,831 (556 ) — — 37,831 (556 ) Obligations of state and political subdivisions 44,714 (785 ) 21,543 (1,402 ) 66,257 (2,187 ) Corporate bonds 1,010 (12 ) — — 1,010 (12 ) Total available-for-sale 270,513 (7,848 ) 78,041 (3,401 ) 348,554 (11,249 ) Total temporarily impaired securities $ 312,080 $ (9,133 ) $ 183,533 $ (8,392 ) $ 495,613 $ (17,525 ) 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 September 30, 2018 , the investment portfolio included 83 investment securities that had been in a continuous unrealized loss position for twelve months or more and 170 investment securities that had been in a loss position for less than twelve months. Securities issued by government-sponsored agencies, such as FNMA and FHLMC, have implicit credit support by the U.S. federal government. Securities issued by the SBA and GNMA have explicit credit guarantees by the U.S. federal government, which protects us from credit losses on the contractual cash flows of the securities. Other temporarily impaired securities, including obligations of state and political subdivisions and corporate bonds, were deemed credit worthy after our internal analyses of the issuers’ latest financial information, credit ratings by major credit rating agencies, and/or credit enhancements. Based on our comprehensive analyses, we determined that the decline in the fair values of these securities was primarily driven by factors other than credit, such as changes in market interest rates and liquidity spreads subsequent to purchase. At September 30, 2018, Management determined that it did not intend to sell investment securities with unrealized losses, and it is more likely than not that we are not required to sell any of the securities with unrealized losses before recovery of their amortized cost. Therefore, we do not consider these investment securities to be other-than-temporarily impaired at September 30, 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 in the consolidated statements of condition at both September 30, 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 October 25, 2018, FHLB announced a cash dividend to be distributed in mid-November 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 to non-member banks of Visa U.S.A. until their conversion into Class A (voting) shares upon the termination of Visa Inc.'s Covered Litigation escrow account. Because of the restriction and the uncertainty on the conversation rate to Class A shares, these shares lack readily determinable fair value and are not classified as available-for-sale securities nor are they carried at fair value. When converting this Class B common stock to Class A common stock based on the conversion rate of 1.6298 as of September 30, 2018 and 1.6483 as of December 31, 2017, and the closing stock price of Class A shares at those respective dates, the converted value of our shares of Class B common stock would have been $4.1 million and $3.2 million at September 30, 2018 and December 31, 2017 , respectively. The conversion rate is subject to further adjustment 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 converted values. For further information, refer to Note 8, Commitments and Contingencies. On October 25, 2018, we entered into an agreement to sell 6,500 shares of our holdings of Visa Class B common stock to a member bank of Visa U.S.A. to be settled in the fourth quarter of 2018, and the estimated net pre-tax gain from the sale is $955 thousand . We invest in low-income housing tax credit funds as a limited partner, which totaled $4.8 million and $2.1 million recorded in other assets as of September 30, 2018 and December 31, 2017 , respectively. We recognized $173 thousand and $454 thousand of low-income housing tax credits and other tax benefits, net of $144 thousand and $381 thousand of amortization expense of low-income housing tax credit investment, as a component of income tax expense in the three and nine months ended September 30, 2018 , respectively. As of September 30, 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 three and nine months ended September 30, 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	9 Months Ended
	Sep. 30, 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 September 30, 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 September 30, 2018 30-59 days past due $ — $ — $ — $ — $ 121 $ — $ 113 $ 234 60-89 days past due 20 — — — — — 47 67 90 days or more past due — — — — — — — — Total past due 20 — — — 121 — 160 301 Current 238,751 316,467 841,493 68,739 121,122 113,383 28,615 1,728,570 Total loans 3 $ 238,771 $ 316,467 $ 841,493 $ 68,739 $ 121,243 $ 113,383 $ 28,775 $ 1,728,871 Non-accrual loans 2 $ — $ — $ — $ — $ 318 $ — $ 68 $ 386 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 Includes no purchased credit impaired ("PCI") loans at September 30, 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 September 30, 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 September 30, 2018 or December 31, 2017 . 3 Amounts include net deferred loan origination costs of $704 thousand and $818 thousand at September 30, 2018 and December 31, 2017 , respectively. Amounts are also net of unaccreted purchase discounts on non-PCI loans of $922 thousand and $1.2 million at September 30, 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 personal guarantees. 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 generally required to submit financial information at regular intervals. Typically, 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. In addition, investor commercial real estate borrowers are usually 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 September 30, 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 September 30, 2018 Pass $ 223,259 $ 302,082 $ 838,493 $ 66,049 $ 119,383 $ 113,383 $ 28,611 $ 2,129 $ 1,693,389 Special Mention 14,574 5,192 2,194 — 1,121 — — — 23,081 Substandard 899 7,995 — 2,690 653 — 164 — 12,401 Total loans $ 238,732 $ 315,269 $ 840,687 $ 68,739 $ 121,157 $ 113,383 $ 28,775 $ 2,129 $ 1,728,871 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 nine months ended September 30, 2018 , one TIC loan and one home equity loan with recorded investments totaling $247 thousand were 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 September 30, 2018 and December 31, 2017 . (in thousands) Recorded investment in Troubled Debt Restructurings 1 September 30, 2018 December 31, 2017 Commercial and industrial $ 1,763 $ 2,165 Commercial real estate, owner-occupied 6,997 6,999 Commercial real estate, investor 1,831 2,171 Construction 2,690 2,969 Home equity 251 347 Other residential 986 1,148 Installment and other consumer 695 721 Total $ 15,213 $ 16,520 1 There were two TDR loans with recorded investments totaling $68 thousand on non-accrual status at September 30, 2018 and no TDR loans on non-accrual status at December 31, 2017 . Includes no acquired loans on TDR status as of September 30, 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 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 TDRs during the three months ended September 30, 2018: None — $ — $ — $ — TDRs during the three months ended September 30, 2017: None — $ — $ — $ — TDRs during the nine months ended September 30, 2018: Commercial and industrial 2 $ 254 $ 245 $ 235 TDRs during the nine months ended September 30, 2017: Installment and consumer 1 $ 50 $ 50 $ 49 The two loans that were modified during the nine months ended September 30, 2018 were to the same borrower and included loan extensions and other changes in loan terms. The modification during the nine months ended September 30, 2017 primarily involved an interest rate concession and other changes to loan terms. During the first nine 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 September 30, 2018 Recorded investment in impaired loans: With no specific allowance recorded $ 304 $ — $ — $ 2,690 $ 318 $ 986 $ 113 $ 4,411 With a specific allowance recorded 1,459 6,997 1,831 — 251 — 582 11,120 Total recorded investment in impaired loans $ 1,763 $ 6,997 $ 1,831 $ 2,690 $ 569 $ 986 $ 695 $ 15,531 Unpaid principal balance of impaired loans $ 1,751 $ 6,993 $ 1,824 $ 2,688 $ 567 $ 985 $ 694 $ 15,502 Specific allowance 173 228 44 — 5 — 77 527 Average recorded investment in impaired loans during the quarter ended 1,840 7,000 1,837 2,690 651 987 700 15,705 Interest income recognized on impaired loans during the quarter ended 1 31 67 20 39 5 13 7 182 Average recorded investment in impaired loans during the nine months ended 2,019 7,002 1,925 2,831 698 1,029 708 16,212 Interest income recognized on impaired loans during the nine months ended 1 214 199 63 114 15 38 22 665 Average recorded investment in impaired loans during the quarter ended 2,063 7,000 3,236 3,104 607 1,164 802 17,976 Interest income recognized on impaired loans during the quarter ended 1 27 67 22 39 5 14 9 183 Average recorded investment in impaired loans during the nine months ended 2,100 6,998 3,010 3,174 660 1,367 871 18,180 Interest income recognized on impaired loans during the nine months ended September 30, 2017 1 74 199 65 110 19 48 29 544 1 Interest income recognized on a cash basis totaling $6 thousand and $134 thousand during the three and nine months ended September 30, 2018 was primarily related to the pay-off of three non-accrual commercial PCI loans. No interest income on impaired loans was recognized on a cash basis during the three and nine months ended September 30, 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 September 30, 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 September 30, 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 $950 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 September 30, 2018 Beginning balance $ 2,597 $ 2,339 $ 7,390 $ 508 $ 952 $ 746 $ 325 $ 956 $ 15,813 Provision (reversal) (245 ) 83 46 157 (39 ) 35 5 (42 ) — Charge-offs — — — — — — — — — Recoveries 4 — — — — — — — 4 Ending balance $ 2,356 $ 2,422 $ 7,436 $ 665 $ 913 $ 781 $ 330 $ 914 $ 15,817 Three months ended September 30, 2017 Beginning balance $ 3,932 $ 2,082 $ 6,065 $ 411 $ 981 $ 509 $ 340 $ 912 $ 15,232 Provision (reversal) 612 (56 ) 33 217 21 33 (5 ) (855 ) — Charge-offs (5 ) — — — — — (1 ) — (6 ) Recoveries 21 — — — — — 1 — 22 Ending balance $ 4,560 $ 2,026 $ 6,098 $ 628 $ 1,002 $ 542 $ 335 $ 57 $ 15,248 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 Nine months ended September 30, 2018 Allowance for loan losses: Beginning balance $ 3,654 $ 2,294 $ 6,475 $ 681 $ 1,031 $ 536 $ 378 $ 718 $ 15,767 Provision (reversal) (1,308 ) 128 961 (16 ) (118 ) 245 (88 ) 196 — Charge-offs (3 ) — — — — — (2 ) — (5 ) Recoveries 13 — — — — — 42 — 55 Ending balance $ 2,356 $ 2,422 $ 7,436 $ 665 $ 913 $ 781 $ 330 $ 914 $ 15,817 Nine months ended September 30, 2017 Allowance for loan losses: Beginning balance $ 3,248 $ 1,753 $ 6,320 $ 781 $ 973 $ 454 $ 372 $ 1,541 $ 15,442 Provision (reversal) 1,509 273 (222 ) (153 ) 29 88 (40 ) (1,484 ) — Charge-offs (289 ) — — — — — (3 ) — (292 ) Recoveries 92 — — — — — 6 — 98 Ending balance $ 4,560 $ 2,026 $ 6,098 $ 628 $ 1,002 $ 542 $ 335 $ 57 $ 15,248 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 September 30, 2018 Ending ALLL related to loans collectively evaluated for impairment $ 2,183 $ 2,194 $ 7,392 $ 665 $ 908 $ 781 $ 253 $ 914 $ 15,290 Ending ALLL related to loans individually evaluated for impairment 173 228 44 — 5 — 77 — 527 Ending ALLL related to PCI loans — — — — — — — — — Ending balance $ 2,356 $ 2,422 $ 7,436 $ 665 $ 913 $ 781 $ 330 $ 914 $ 15,817 Recorded Investment: Collectively evaluated for impairment $ 236,969 $ 308,272 $ 838,856 $ 66,049 $ 120,588 $ 112,397 $ 28,080 $ — $ 1,711,211 Individually evaluated for impairment 1,763 6,997 1,831 2,690 569 986 695 — 15,531 PCI loans 39 1,198 806 — 86 — — — 2,129 Total $ 238,771 $ 316,467 $ 841,493 $ 68,739 $ 121,243 $ 113,383 $ 28,775 $ — $ 1,728,871 Ratio of allowance for loan losses to total loans 0.99 % 0.77 % 0.88 % 0.97 % 0.75 % 0.69 % 1.15 % NM 0.91 % Allowance for loan losses to non-accrual loans NM NM NM NM 287 % NM 485 % NM 4,098 % 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 September 30, 2018 December 31, 2017 (in thousands) Unpaid Principal Balance Carrying Value Unpaid Principal Balance Carrying Value Commercial and industrial $ 106 $ 39 $ 276 $ 65 Commercial real estate, owner occupied 1,259 1,198 1,297 1,166 Commercial real estate, investor 1,041 806 1,064 790 Home equity 215 86 231 94 Total purchased credit-impaired loans $ 2,621 $ 2,129 $ 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 Nine months ended (in thousands) September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Balance at beginning of period $ 1,059 $ 1,306 $ 1,254 $ 1,476 Accretion (63 ) (76 ) (258 ) (246 ) Balance at end of period $ 996 $ 1,230 $ 996 $ 1,230 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 $1,031.5 million and $887.9 million at September 30, 2018 and December 31, 2017 , respectively. In addition, we pledge a certain residential loan portfolio, which totaled $85.2 million and $67.6 million at September 30, 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 September 30, 2018 compared to $11.9 million at December 31, 2017 . In addition, undisbursed commitments to related parties totaled $9.1 million at September 30, 2018 and December 31, 2017 .

Borrowings

Borrowings	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Borrowings	Borrowings Federal Funds Purchased – The Bank had unsecured lines of credit with correspondent banks for overnight borrowing totaling $92.0 million at September 30, 2018 and $100.4 million at 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 September 30, 2018 or December 31, 2017 . Federal Home Loan Bank Borrowings – As of September 30, 2018 and December 31, 2017 , the Bank had lines of credit with the FHLB totaling $616.2 million and $538.9 million , respectively, based on eligible collateral of certain loans. There were no FHLB overnight borrowings at September 30, 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 September 30, 2018 and December 31, 2017 , the Bank had borrowing capacity under this line totaling $64.4 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 $92 thousand and $117 thousand in the nine months ended September 30, 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 September 30, 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 (5.39% as of September 30, 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 (3.73% as of September 30, 2018), redeemable, in whole or in part, on any interest payment date 4,124 Total $ 8,248 On October 5, 2018, Bancorp redeemed in full the subordinated debentures due to NorCal Community Bancorp Trust I resulting in $916 thousand in accelerated accretion, which will have a one-time impact on net interest income in the fourth quarter of 2018, but will not have a material impact on our capital ratios.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Stockholders' Equity	Stockholders' Equity Dividend and Stock Split On October 22, 2018, the Bancorp declared a $0.35 per share cash dividend, payable on November 8, 2018 to shareholders of record at the close of business on November 1, 2018. Additionally, Bancorp announced a 2 :1 stock split, payable on November 27, 2018, to shareholders of record at the close of business on November 9, 2018. See Note 1, Basis of Presentation, for the pro forma effect of the stock split on reported earnings per share for the periods presented. 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, which is generally the vesting period, with a corresponding increase in common stock. Stock-based compensation also includes compensation expense related to the issuance of restricted stock awards. The fair value of the restricted stock awards on the grant date, which equals the intrinsic value, is recorded as compensation expense over the requisite service period with a corresponding increase in common stock as the shares vest. Stock option and restricted stock awards issued in 2018 include a retirement eligibility clause whereby the requisite service period is satisfied at the retirement eligibility date. For those awards, we accelerate stock-based compensation if the award holder is eligible to retire. However, retirement eligibility does not affect the legal vesting schedule of the awards. 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 nine months ended September 30, 2018 , option holders exchanged 20,981 shares totaling $1.5 million at a weighted-average price of $71.35 for cashless stock option exercises and tax withholdings upon vesting of performance-based stock awards. During the nine months ended September 30, 2017 , option holders exchanged 11,938 shares totaling $782 thousand at a weighted-average price of $65.50 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 entered 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 times that might otherwise be prohibited 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. During the nine months ended September 30, 2018 , Bancorp purchased 17,943 shares for a total amount of $1.5 million .

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 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 in the consolidated statements of condition are as follows: (in thousands) September 30, 2018 December 31, 2017 Commercial lines of credit $ 228,932 $ 224,370 Revolving home equity lines 189,353 177,678 Undisbursed construction loans 51,624 35,322 Personal and other lines of credit 10,783 11,758 Standby letters of credit 2,636 4,074 Total commitments and standby letters of credit $ 483,328 $ 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 September 30, 2018 and December 31, 2017 , which is recorded in interest payable and other liabilities in 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 September 30, 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 $ 1,106 $ 4,198 $ 3,758 $ 2,138 $ 1,330 $ 2,904 $ 15,434 Rent expense included in occupancy expense totaled $1.1 million and $997 thousand for the three months ended September 30, 2018 and 2017 , respectively. Rent expense totaled $3.5 million and $ 3.0 million for the nine months ended September 30, 2018 and 2017 , respectively. 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. The Bank is responsible for a proportionate share of certain litigation indemnifications provided to Visa U.S.A. ("Visa") by its member banks in connection with Visa's lawsuits related to anti-trust charges and interchange fees ("Covered Litigation"). Our proportionate share of the litigation indemnification liability does not change or transfer upon the sale of our Class B Visa shares to member banks. Visa established an escrow account to pay for settlements or judgments in the Covered Litigation. Under the terms of the U.S. retrospective responsibility plan, when Visa funds the litigation escrow account, it triggers a conversion rate reduction of the Class B common stock to shares of Class A common stock, effectively reducing the aggregate value of the Class B common stock held by Visa's member banks like us. In 2012, Visa had reached a $4.0 billion interchange multidistrict litigation class settlement agreement with plaintiffs representing a class of U.S. retailers. On September 17, 2018, Visa signed an amended settlement agreement with the class action plaintiffs of the U.S. interchange multidistrict litigation that superseded the 2012 settlement agreement. Pursuant to the amended settlement agreement, Visa deposited an additional $600 million into the litigation escrow account, increasing the escrow account balance to $1.5 billion . The escrow balance, combined with funds previously deposited with the court, are expected to cover all settlement payment obligations. According to Visa's Form 10-Q filed on July 27, 2018, 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. The outcome of the Covered Litigation affects the conversion rate of Visa Class B common stock held by us to Visa Class A common stock, as discussed above and in Note 4, Investment Securities. The final conversion rate might change depending on the final settlement payments, and the full effect on member banks is still uncertain. Litigation is ongoing and until the court approval process is complete, there is no assurance that Visa will resolve the claims as contemplated by the settlement agreement and additional lawsuits may arise. However, until the escrow account is fully depleted and the conversion rate of Class B to Class A common stock is reduced to zero, no future cash settlement payments are required by the member banks, such as us, on the Covered Litigation. Therefore, we are not required to record any indemnification liabilities related to the Covered Litigation.

Derivative Financial Instrument

Derivative Financial Instruments and Hedging Activities	9 Months Ended
	Sep. 30, 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 interest rate risk 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 September 30, 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 designated hedging instruments and 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 $4 thousand and $8 thousand as of September 30, 2018 and December 31, 2017 , respectively. The following table presents the notional amount and fair value of our derivatives designated as hedging instruments: Derivative Assets Derivative Liabilities (in thousands) September 30, December 31, 2017 September 30, December 31, 2017 Fair value hedges: Interest rate contracts notional amount $ 8,988 $ 4,019 $ 9,156 $ 14,810 Interest rate contracts fair value 1 $ 436 $ 74 $ 163 $ 740 1 See Note 3, Fair Value of Assets and Liabilities, for valuation methodology. The following table presents the carrying amount and associated cumulative basis adjustment related to the application of fair value hedge accounting that is included in the carrying amount of hedged assets as of September 30, 2018 : (in thousands) Carrying Amounts of Hedged Assets Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Loans Loans $ 17,651 $ (493 ) The following table presents the net gains (losses) recognized in interest income on loans on the consolidated statements of comprehensive income related to our derivatives designated as fair value hedges: Three months ended (in thousands) September 30, 2018 September 30, 2017 Increase in value of designated interest rate swaps $ 222 $ 25 Payment on interest rate swaps $ (32 ) $ (76 ) Decrease in value of hedged loans $ (231 ) $ (43 ) Decrease in value of yield maintenance agreement $ (4 ) $ (4 ) Net loss on fair value hedging relationships recognized in interest income $ (45 ) $ (98 ) Nine months ended (in thousands) September 30, 2018 September 30, 2017 Increase in value of designated interest rate swaps $ 939 $ 7 Payment on interest rate swaps $ (127 ) $ (261 ) (Decrease) increase in value of hedged loans $ (924 ) $ 35 Decrease in value of yield maintenance agreement $ (11 ) $ (11 ) Net loss on fair value hedging relationships recognized against interest income $ (123 ) $ (230 ) 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. The following table shows information on financial instruments that are eligible for offset in the consolidated statements of condition. 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 September 30, 2018 Derivatives by Counterparty: Counterparty A $ 436 $ — $ 436 $ (163 ) $ — $ 273 December 31, 2017 Derivatives by Counterparty: Counterparty A $ 74 $ — $ 74 $ (74 ) $ — $ — 1 Amounts exclude accrued interest totaling less than $1 thousand at both September 30, 2018 and December 31, 2017 . 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 September 30, 2018 Derivatives by Counterparty: Counterparty A $ 163 $ — $ 163 $ (163 ) $ — December 31, 2017 Derivatives by Counterparty: Counterparty A $ 740 $ — $ 740 $ (74 ) $ (666 ) $ — 2 Amounts exclude accrued interest totaling $3 thousand and $8 thousand at September 30, 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	9 Months Ended
	Sep. 30, 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 $381 thousand was amortized in the first nine months of 2018. The core deposit intangible 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 September 30, 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 and nine months ended September 30, 2018 as follows: Three months ended Nine months ended (in thousands) September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Data processing 1 $ 43 $ — $ 598 $ — Professional services 46 449 172 458 Personnel severance — — 141 — Other — 46 43 46 Total $ 89 $ 495 $ 954 $ 504 1 Primarily relates to Bank of Napa's core processing system contract termination and deconversion fees.

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 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 accounts for its investment in the securities of the Trusts under the equity method, which is included in interest receivable and other assets in 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 the quarterly diluted EPS is computed using the average market prices during the three months included in the reporting period under the treasury stock method. 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 Adopted and 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 revenue recognition 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 we complete our performance obligation 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 the payment networks process transactions. 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. 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 for the periods presented. 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 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. We early adopted the amendments of this ASU in the second quarter of 2018, and elected to perform hedge effectiveness assessments using a qualitative approach instead of quantitative regression analysis going forward. The adoption of this ASU had an immaterial impact to our financial results. The amendments also require additional disclosures, which are included in Note 9, Derivative Financial Instruments and Hedging Activities. 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. In July 2018, the FASB issued two amendments to ASU 2016-02: ASU No. 2018-10, Codification Improvements to Topic 842, Leases , which provides various corrections and clarifications to ASU 2016-02; and ASU No. 2018-11, Leases (Topic 842): Targeted Improvements , which provides a new optional transition method and provides a lessor with practical expedients for separating lease and non-lease components of a lease. Early application of the amendments is permitted. We intend to adopt this ASU during the first quarter of 2019, as required. We completed an inventory of our lease agreements and selected a lease accounting software solution. We are in the process of abstracting and inputting lease-related data, developing policies and procedures, and designing related internal controls. As of September 30, 2018 , our undiscounted operating lease obligations that were off-balance sheet totaled $15.4 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 retained earnings, capital ratios, results of operations or return on average assets when adopted. 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 present financial assets at the net amount expected to be collected. 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 expected 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. The impact of this ASU on our financial condition and results of operations is not known at this time. In June 2018, the FASB issued ASU No. 2018-07, Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting . This update simplifies the accounting for share-based payment transactions for acquiring goods and services from nonemployees, applying some of the same requirements as employee share-based payment transactions. The ASU will not affect the accounting for share-based payment awards to nonemployee directors, which will continue to be treated as employee share-based transactions under the current standards. ASU 2018-07 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. We do not expect that the ASU will have a material impact on our financial condition or results of operations, as it is not our practice to issue stock-based awards to pay for goods and services from nonemployees, other than nonemployee directors. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement . The amendments in this ASU remove, modify and add disclosure requirements for the fair value reporting of assets and liabilities. The modifications and additions relate to Level 3 fair value measurements at the end of the reporting period. ASU 2018-13 is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted. Entities making this election are permitted to early adopt the eliminated or modified disclosure requirements and delay the adoption of all the new disclosure requirements until the ASU's effective date. We do not expect that the ASU will have a material impact on our financial condition or results of operations. In August 2018, the FASB issued ASU No. 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract . This standard aligns the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software, regardless of whether they convey a license to the hosted software. The accounting for the service element of a hosting arrangement that is a service contract is not affected by this ASU. The amendments are effective for public business entities for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. We do not expect that the ASU will have a material impact on our financial condition or results of operations. In October 2018, the FASB issued ASU No. 2018-16, Derivatives and Hedging (Topic 815): Inclusion of the Secured Overnight Financing Rate (SOFR) Overnight Index Swap (OIS) Rate as a Benchmark Interest Rate for Hedge Accounting Purposes . This update adds an alternative fifth permissible U.S. benchmark rate to be used for hedge accounting purposes. As we have already adopted the amendments in ASU 2017-12, which changed both the designation and measurement guidance for qualifying hedging relationships, the amendments in ASU 2018-16 are effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted in any interim period upon issuance of this ASU if an entity already has adopted ASU 2017-12. 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 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. No such transfers occurred during the first nine months of 2018 or 2017.
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 personal guarantees. 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 generally required to submit financial information at regular intervals. Typically, 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. In addition, investor commercial real estate borrowers are usually 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)	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Earnings Per Share Reconciliation and Proforma EPS	On October 22, 2018, the Bancorp announced a 2 :1 stock split, payable on November 27, 2018, to shareholders of record at the close of business on November 9, 2018. Pro forma per share amounts are shown below to reflect the stock split, effective November 27, 2018. Three months ended Nine months ended (in thousands, except per share data) September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Basic EPS $ 0.62 $ 0.42 $ 1.66 $ 1.22 Diluted EPS $ 0.62 $ 0.41 $ 1.63 $ 1.20 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 the quarterly diluted EPS is computed using the average market prices during the three months included in the reporting period under the treasury stock method. 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 Nine months ended (in thousands, except per share data) September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Weighted average basic shares outstanding 6,950 6,123 6,936 6,109 Potentially dilutive common shares related to: Stock options 88 53 79 55 Unvested restricted stock awards 17 15 16 15 Weighted average diluted shares outstanding 7,055 6,191 7,031 6,179 Net income $ 8,680 $ 5,132 $ 22,960 $ 14,866 Basic EPS $ 1.25 $ 0.84 $ 3.31 $ 2.43 Diluted EPS $ 1.23 $ 0.83 $ 3.27 $ 2.41 Weighted average anti-dilutive shares not included in the calculation of diluted EPS — 23 1 19

Fair Value of Assets and Liab_2

Fair Value of Assets and Liabilities (Tables)	9 Months Ended
	Sep. 30, 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 September 30, 2018 Securities available-for-sale: Mortgage-backed securities and collateralized mortgage obligations issued by U.S. government agencies $ 246,220 $ — $ 246,220 $ — OCI SBA-backed securities 40,181 — 40,181 — OCI Debentures of government sponsored agencies 42,914 — 42,914 — OCI Privately-issued collateralized mortgage obligations 370 — 370 — OCI Obligations of state and political subdivisions 73,373 — 73,373 — OCI Corporate bonds 2,513 — 2,513 — OCI Derivative financial assets (interest rate contracts) 436 — 436 — NI Derivative financial liabilities (interest rate contracts) 163 — 163 — 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").
Schedule of Fair Value by Balance Sheet Grouping	The following table summarizes fair value estimates for financial instruments as of September 30, 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. September 30, 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 $ 142,718 $ 142,718 Level 1 $ 203,545 $ 203,545 Level 1 Investment securities held-to-maturity 164,222 158,106 Level 2 151,032 151,032 Level 2 Loans, net 1,713,054 1,683,109 Level 3 1,663,246 1,650,198 Level 3 Interest receivable 7,366 7,366 Level 2 7,501 7,501 Level 2 Financial liabilities (recorded at amortized cost) Time deposits 126,140 124,796 Level 2 160,116 159,540 Level 2 Subordinated debentures 5,831 7,505 Level 3 5,739 5,118 Level 3 Interest payable 155 155 Level 2 191 191 Level 2

Investment Securities (Tables)

Investment Securities (Tables)	9 Months Ended
	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Summary of Held-to-Maturity Investments	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"), Small Business Administration ("SBA"), or Government National Mortgage Association ("GNMA"), debentures issued by government-sponsored agencies such as FNMA, Federal Farm Credit Bureau, FHLB and FHLMC, and privately issued CMOs, as reflected in the following table. September 30, 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: Securities of U.S. government agencies: MBS pass-through securities issued by FHLMC and FNMA $ 91,237 $ 86,962 $ — $ (4,275 ) $ 100,376 $ 100,096 $ 234 $ (514 ) SBA-backed securities 8,723 8,489 — (234 ) — — — — CMOs issued by FNMA 11,646 11,254 — (392 ) — — — — CMOs issued by FHLMC 34,169 32,868 — (1,301 ) 31,010 30,938 2 (74 ) CMOs issued by GNMA 3,734 3,694 — (40 ) — — — — Obligations of state and political subdivisions 14,713 14,839 160 (34 ) 19,646 19,998 383 (31 ) Total held-to-maturity 164,222 158,106 160 (6,276 ) 151,032 151,032 619 (619 ) Available-for-sale: Securities of U.S. government agencies: MBS pass-through securities issued by FHLMC and FNMA 93,096 90,484 20 (2,632 ) 65,559 65,262 126 (423 ) SBA-backed securities 41,074 40,181 — (893 ) 25,979 25,982 58 (55 ) CMOs issued by FNMA 19,914 19,356 4 (562 ) 35,340 35,125 33 (248 ) CMOs issued by FHLMC 128,848 124,930 1 (3,919 ) 70,514 69,889 3 (628 ) CMOs issued by GNMA 11,938 11,450 — (488 ) 17,953 17,785 26 (194 ) Debentures of government- sponsored agencies 43,470 42,914 — (556 ) 12,940 12,938 3 (5 ) Privately issued CMOs 367 370 3 — 1,432 1,431 1 (2 ) Obligations of state and political subdivisions 75,519 73,373 41 (2,187 ) 98,027 97,491 298 (834 ) Corporate bonds 2,506 2,513 19 (12 ) 6,541 6,564 26 (3 ) Total available-for-sale 416,732 405,571 88 (11,249 ) 334,285 332,467 574 (2,392 ) Total investment securities $ 580,954 $ 563,677 $ 248 $ (17,525 ) $ 485,317 $ 483,499 $ 1,193 $ (3,011 )
Summary of Available-for-Sale Investments	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"), Small Business Administration ("SBA"), or Government National Mortgage Association ("GNMA"), debentures issued by government-sponsored agencies such as FNMA, Federal Farm Credit Bureau, FHLB and FHLMC, and privately issued CMOs, as reflected in the following table. September 30, 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: Securities of U.S. government agencies: MBS pass-through securities issued by FHLMC and FNMA $ 91,237 $ 86,962 $ — $ (4,275 ) $ 100,376 $ 100,096 $ 234 $ (514 ) SBA-backed securities 8,723 8,489 — (234 ) — — — — CMOs issued by FNMA 11,646 11,254 — (392 ) — — — — CMOs issued by FHLMC 34,169 32,868 — (1,301 ) 31,010 30,938 2 (74 ) CMOs issued by GNMA 3,734 3,694 — (40 ) — — — — Obligations of state and political subdivisions 14,713 14,839 160 (34 ) 19,646 19,998 383 (31 ) Total held-to-maturity 164,222 158,106 160 (6,276 ) 151,032 151,032 619 (619 ) Available-for-sale: Securities of U.S. government agencies: MBS pass-through securities issued by FHLMC and FNMA 93,096 90,484 20 (2,632 ) 65,559 65,262 126 (423 ) SBA-backed securities 41,074 40,181 — (893 ) 25,979 25,982 58 (55 ) CMOs issued by FNMA 19,914 19,356 4 (562 ) 35,340 35,125 33 (248 ) CMOs issued by FHLMC 128,848 124,930 1 (3,919 ) 70,514 69,889 3 (628 ) CMOs issued by GNMA 11,938 11,450 — (488 ) 17,953 17,785 26 (194 ) Debentures of government- sponsored agencies 43,470 42,914 — (556 ) 12,940 12,938 3 (5 ) Privately issued CMOs 367 370 3 — 1,432 1,431 1 (2 ) Obligations of state and political subdivisions 75,519 73,373 41 (2,187 ) 98,027 97,491 298 (834 ) Corporate bonds 2,506 2,513 19 (12 ) 6,541 6,564 26 (3 ) Total available-for-sale 416,732 405,571 88 (11,249 ) 334,285 332,467 574 (2,392 ) Total investment securities $ 580,954 $ 563,677 $ 248 $ (17,525 ) $ 485,317 $ 483,499 $ 1,193 $ (3,011 )
Investments Classified by Contractual Maturity Date	The amortized cost a nd fair value of investment debt securities by contractual maturity at September 30, 2018 and December 31, 2017 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. September 30, 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 $ 2,677 $ 2,697 $ 10,111 $ 10,031 $ 2,151 $ 2,172 $ 10,268 $ 10,272 After one but within five years 12,476 12,438 69,230 67,972 15,577 15,791 71,576 71,237 After five years through ten years 60,422 58,041 239,939 232,532 54,641 54,554 129,723 128,954 After ten years 88,647 84,930 97,452 95,036 78,663 78,515 122,718 122,004 Total $ 164,222 $ 158,106 $ 416,732 $ 405,571 $ 151,032 $ 151,032 $ 334,285 $ 332,467
Sale of Investment Securities and Gross Gains and Losses	Sales of investment securities and gross gains and losses are shown in the following table. Three months ended Nine months ended (in thousands) September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Available-for-sale: Sales proceeds $ 11,966 $ — $ 16,972 $ 1,321 Gross realized gains — — 27 13 Gross realized losses (90 ) — (106 ) (3 )
Schedule of Financial Instruments Owned and Pledged as Collateral	Pledged investment securities are shown in the following table. (in thousands) September 30, 2018 December 31, 2017 Pledged to the State of California: Secure public deposits in compliance with the Local Agency Security Program $ 97,978 $ 107,829 Collateral for trust deposits 740 761 Total investment securities pledged to the State of California $ 98,718 $ 108,590 Collateral for Wealth Management and Trust Services checking account $ 2,005 $ 2,026
Schedule of Unrealized Loss on Investments	There were 253 and 198 investment securities in unrealized loss positions at September 30, 2018 and December 31, 2017 , respectively. Those securities are summarized and classified according to the duration of the loss period in the following tables: September 30, 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: MBS pass-through securities issued by FHLMC and FNMA $ 6,602 $ (225 ) $ 80,360 $ (4,050 ) $ 86,962 $ (4,275 ) SBA-backed securities 8,489 (234 ) — — $ 8,489 $ (234 ) CMOs issued by FNMA 11,254 (392 ) — — 11,254 (392 ) CMOs issued by FHLMC 11,430 (400 ) 21,438 (901 ) 32,868 (1,301 ) CMOs issued by GNMA — — 3,694 (40 ) 3,694 (40 ) Obligations of state and political subdivisions 3,792 (34 ) — — 3,792 (34 ) Total held-to-maturity 41,567 (1,285 ) 105,492 (4,991 ) 147,059 (6,276 ) Available-for-sale: MBS pass-through securities issued by FHLMC and FNMA 52,821 (1,804 ) 20,406 (828 ) 73,227 (2,632 ) SBA-backed securities 23,162 (893 ) — — 23,162 (893 ) CMOs issued by FNMA 13,230 (383 ) 5,905 (179 ) 19,135 (562 ) CMOs issued by FHLMC 87,017 (2,930 ) 29,702 (989 ) 116,719 (3,919 ) CMOs issued by GNMA 10,728 (485 ) 485 (3 ) 11,213 (488 ) Debentures of government- sponsored agencies 37,831 (556 ) — — 37,831 (556 ) Obligations of state and political subdivisions 44,714 (785 ) 21,543 (1,402 ) 66,257 (2,187 ) Corporate bonds 1,010 (12 ) — — 1,010 (12 ) Total available-for-sale 270,513 (7,848 ) 78,041 (3,401 ) 348,554 (11,249 ) Total temporarily impaired securities $ 312,080 $ (9,133 ) $ 183,533 $ (8,392 ) $ 495,613 $ (17,525 ) 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 _2

Loans and Allowance for Loan Losses (Tables)	9 Months Ended
	Sep. 30, 2018
Receivables [Abstract]
Past Due Financing Receivables	The following table shows outstanding loans by class and payment aging as of September 30, 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 September 30, 2018 30-59 days past due $ — $ — $ — $ — $ 121 $ — $ 113 $ 234 60-89 days past due 20 — — — — — 47 67 90 days or more past due — — — — — — — — Total past due 20 — — — 121 — 160 301 Current 238,751 316,467 841,493 68,739 121,122 113,383 28,615 1,728,570 Total loans 3 $ 238,771 $ 316,467 $ 841,493 $ 68,739 $ 121,243 $ 113,383 $ 28,775 $ 1,728,871 Non-accrual loans 2 $ — $ — $ — $ — $ 318 $ — $ 68 $ 386 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 Includes no purchased credit impaired ("PCI") loans at September 30, 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 September 30, 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 September 30, 2018 or December 31, 2017 . 3 Amounts include net deferred loan origination costs of $704 thousand and $818 thousand at September 30, 2018 and December 31, 2017 , respectively. Amounts are also net of unaccreted purchase discounts on non-PCI loans of $922 thousand and $1.2 million at September 30, 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 September 30, 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 September 30, 2018 Pass $ 223,259 $ 302,082 $ 838,493 $ 66,049 $ 119,383 $ 113,383 $ 28,611 $ 2,129 $ 1,693,389 Special Mention 14,574 5,192 2,194 — 1,121 — — — 23,081 Substandard 899 7,995 — 2,690 653 — 164 — 12,401 Total loans $ 238,732 $ 315,269 $ 840,687 $ 68,739 $ 121,157 $ 113,383 $ 28,775 $ 2,129 $ 1,728,871 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 September 30, 2018 and December 31, 2017 . (in thousands) Recorded investment in Troubled Debt Restructurings 1 September 30, 2018 December 31, 2017 Commercial and industrial $ 1,763 $ 2,165 Commercial real estate, owner-occupied 6,997 6,999 Commercial real estate, investor 1,831 2,171 Construction 2,690 2,969 Home equity 251 347 Other residential 986 1,148 Installment and other consumer 695 721 Total $ 15,213 $ 16,520 1 There were two TDR loans with recorded investments totaling $68 thousand on non-accrual status at September 30, 2018 and no TDR loans on non-accrual status at December 31, 2017 . Includes no acquired loans on TDR status as of September 30, 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 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 TDRs during the three months ended September 30, 2018: None — $ — $ — $ — TDRs during the three months ended September 30, 2017: None — $ — $ — $ — TDRs during the nine months ended September 30, 2018: Commercial and industrial 2 $ 254 $ 245 $ 235 TDRs during the nine months ended September 30, 2017: Installment and consumer 1 $ 50 $ 50 $ 49
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 September 30, 2018 Recorded investment in impaired loans: With no specific allowance recorded $ 304 $ — $ — $ 2,690 $ 318 $ 986 $ 113 $ 4,411 With a specific allowance recorded 1,459 6,997 1,831 — 251 — 582 11,120 Total recorded investment in impaired loans $ 1,763 $ 6,997 $ 1,831 $ 2,690 $ 569 $ 986 $ 695 $ 15,531 Unpaid principal balance of impaired loans $ 1,751 $ 6,993 $ 1,824 $ 2,688 $ 567 $ 985 $ 694 $ 15,502 Specific allowance 173 228 44 — 5 — 77 527 Average recorded investment in impaired loans during the quarter ended 1,840 7,000 1,837 2,690 651 987 700 15,705 Interest income recognized on impaired loans during the quarter ended 1 31 67 20 39 5 13 7 182 Average recorded investment in impaired loans during the nine months ended 2,019 7,002 1,925 2,831 698 1,029 708 16,212 Interest income recognized on impaired loans during the nine months ended 1 214 199 63 114 15 38 22 665 Average recorded investment in impaired loans during the quarter ended 2,063 7,000 3,236 3,104 607 1,164 802 17,976 Interest income recognized on impaired loans during the quarter ended 1 27 67 22 39 5 14 9 183 Average recorded investment in impaired loans during the nine months ended 2,100 6,998 3,010 3,174 660 1,367 871 18,180 Interest income recognized on impaired loans during the nine months ended September 30, 2017 1 74 199 65 110 19 48 29 544 1 Interest income recognized on a cash basis totaling $6 thousand and $134 thousand during the three and nine months ended September 30, 2018 was primarily related to the pay-off of three non-accrual commercial PCI loans. No interest income on impaired loans was recognized on a cash basis during the three and nine months ended September 30, 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 September 30, 2018 Beginning balance $ 2,597 $ 2,339 $ 7,390 $ 508 $ 952 $ 746 $ 325 $ 956 $ 15,813 Provision (reversal) (245 ) 83 46 157 (39 ) 35 5 (42 ) — Charge-offs — — — — — — — — — Recoveries 4 — — — — — — — 4 Ending balance $ 2,356 $ 2,422 $ 7,436 $ 665 $ 913 $ 781 $ 330 $ 914 $ 15,817 Three months ended September 30, 2017 Beginning balance $ 3,932 $ 2,082 $ 6,065 $ 411 $ 981 $ 509 $ 340 $ 912 $ 15,232 Provision (reversal) 612 (56 ) 33 217 21 33 (5 ) (855 ) — Charge-offs (5 ) — — — — — (1 ) — (6 ) Recoveries 21 — — — — — 1 — 22 Ending balance $ 4,560 $ 2,026 $ 6,098 $ 628 $ 1,002 $ 542 $ 335 $ 57 $ 15,248 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 Nine months ended September 30, 2018 Allowance for loan losses: Beginning balance $ 3,654 $ 2,294 $ 6,475 $ 681 $ 1,031 $ 536 $ 378 $ 718 $ 15,767 Provision (reversal) (1,308 ) 128 961 (16 ) (118 ) 245 (88 ) 196 — Charge-offs (3 ) — — — — — (2 ) — (5 ) Recoveries 13 — — — — — 42 — 55 Ending balance $ 2,356 $ 2,422 $ 7,436 $ 665 $ 913 $ 781 $ 330 $ 914 $ 15,817 Nine months ended September 30, 2017 Allowance for loan losses: Beginning balance $ 3,248 $ 1,753 $ 6,320 $ 781 $ 973 $ 454 $ 372 $ 1,541 $ 15,442 Provision (reversal) 1,509 273 (222 ) (153 ) 29 88 (40 ) (1,484 ) — Charge-offs (289 ) — — — — — (3 ) — (292 ) Recoveries 92 — — — — — 6 — 98 Ending balance $ 4,560 $ 2,026 $ 6,098 $ 628 $ 1,002 $ 542 $ 335 $ 57 $ 15,248 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 September 30, 2018 Ending ALLL related to loans collectively evaluated for impairment $ 2,183 $ 2,194 $ 7,392 $ 665 $ 908 $ 781 $ 253 $ 914 $ 15,290 Ending ALLL related to loans individually evaluated for impairment 173 228 44 — 5 — 77 — 527 Ending ALLL related to PCI loans — — — — — — — — — Ending balance $ 2,356 $ 2,422 $ 7,436 $ 665 $ 913 $ 781 $ 330 $ 914 $ 15,817 Recorded Investment: Collectively evaluated for impairment $ 236,969 $ 308,272 $ 838,856 $ 66,049 $ 120,588 $ 112,397 $ 28,080 $ — $ 1,711,211 Individually evaluated for impairment 1,763 6,997 1,831 2,690 569 986 695 — 15,531 PCI loans 39 1,198 806 — 86 — — — 2,129 Total $ 238,771 $ 316,467 $ 841,493 $ 68,739 $ 121,243 $ 113,383 $ 28,775 $ — $ 1,728,871 Ratio of allowance for loan losses to total loans 0.99 % 0.77 % 0.88 % 0.97 % 0.75 % 0.69 % 1.15 % NM 0.91 % Allowance for loan losses to non-accrual loans NM NM NM NM 287 % NM 485 % NM 4,098 % 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 September 30, 2018 December 31, 2017 (in thousands) Unpaid Principal Balance Carrying Value Unpaid Principal Balance Carrying Value Commercial and industrial $ 106 $ 39 $ 276 $ 65 Commercial real estate, owner occupied 1,259 1,198 1,297 1,166 Commercial real estate, investor 1,041 806 1,064 790 Home equity 215 86 231 94 Total purchased credit-impaired loans $ 2,621 $ 2,129 $ 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 Nine months ended (in thousands) September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Balance at beginning of period $ 1,059 $ 1,306 $ 1,254 $ 1,476 Accretion (63 ) (76 ) (258 ) (246 ) Balance at end of period $ 996 $ 1,230 $ 996 $ 1,230

Borrowings (Tables)

Borrowings (Tables)	9 Months Ended
	Sep. 30, 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 September 30, 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 (5.39% as of September 30, 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 (3.73% as of September 30, 2018), redeemable, in whole or in part, on any interest payment date 4,124 Total $ 8,248

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 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 in the consolidated statements of condition are as follows: (in thousands) September 30, 2018 December 31, 2017 Commercial lines of credit $ 228,932 $ 224,370 Revolving home equity lines 189,353 177,678 Undisbursed construction loans 51,624 35,322 Personal and other lines of credit 10,783 11,758 Standby letters of credit 2,636 4,074 Total commitments and standby letters of credit $ 483,328 $ 453,202
Schedule of Future Minimum Rental Payments for Operating Leases	At September 30, 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 $ 1,106 $ 4,198 $ 3,758 $ 2,138 $ 1,330 $ 2,904 $ 15,434

Derivative Financial Instrume_2

Derivative Financial Instruments and Hedging Activities (Tables)	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	The following table presents the notional amount and fair value of our derivatives designated as hedging instruments: Derivative Assets Derivative Liabilities (in thousands) September 30, December 31, 2017 September 30, December 31, 2017 Fair value hedges: Interest rate contracts notional amount $ 8,988 $ 4,019 $ 9,156 $ 14,810 Interest rate contracts fair value 1 $ 436 $ 74 $ 163 $ 740 1 See Note 3, Fair Value of Assets and Liabilities, for valuation methodology. The following table presents the carrying amount and associated cumulative basis adjustment related to the application of fair value hedge accounting that is included in the carrying amount of hedged assets as of September 30, 2018 : (in thousands) Carrying Amounts of Hedged Assets Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Loans Loans $ 17,651 $ (493 )
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance	The following table presents the net gains (losses) recognized in interest income on loans on the consolidated statements of comprehensive income related to our derivatives designated as fair value hedges: Three months ended (in thousands) September 30, 2018 September 30, 2017 Increase in value of designated interest rate swaps $ 222 $ 25 Payment on interest rate swaps $ (32 ) $ (76 ) Decrease in value of hedged loans $ (231 ) $ (43 ) Decrease in value of yield maintenance agreement $ (4 ) $ (4 ) Net loss on fair value hedging relationships recognized in interest income $ (45 ) $ (98 ) Nine months ended (in thousands) September 30, 2018 September 30, 2017 Increase in value of designated interest rate swaps $ 939 $ 7 Payment on interest rate swaps $ (127 ) $ (261 ) (Decrease) increase in value of hedged loans $ (924 ) $ 35 Decrease in value of yield maintenance agreement $ (11 ) $ (11 ) Net loss on fair value hedging relationships recognized against interest income $ (123 ) $ (230 )
Offsetting Assets	The following table shows information on financial instruments that are eligible for offset in the consolidated statements of condition. 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 September 30, 2018 Derivatives by Counterparty: Counterparty A $ 436 $ — $ 436 $ (163 ) $ — $ 273 December 31, 2017 Derivatives by Counterparty: Counterparty A $ 74 $ — $ 74 $ (74 ) $ — $ — 1 Amounts exclude accrued interest totaling less than $1 thousand at both September 30, 2018 and December 31, 2017 . 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 September 30, 2018 Derivatives by Counterparty: Counterparty A $ 163 $ — $ 163 $ (163 ) $ — 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 September 30, 2018 Derivatives by Counterparty: Counterparty A $ 163 $ — $ 163 $ (163 ) $ — December 31, 2017 Derivatives by Counterparty: Counterparty A $ 740 $ — $ 740 $ (74 ) $ (666 ) $ — 2 Amounts exclude accrued interest totaling $3 thousand and $8 thousand at September 30, 2018 and December 31, 2017 , respectively.

Acquisition (Tables)

Acquisition (Tables)	9 Months Ended
	Sep. 30, 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 and nine months ended September 30, 2018 as follows: Three months ended Nine months ended (in thousands) September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Data processing 1 $ 43 $ — $ 598 $ — Professional services 46 449 172 458 Personnel severance — — 141 — Other — 46 43 46 Total $ 89 $ 495 $ 954 $ 504 1 Primarily relates to Bank of Napa's core processing system contract termination and deconversion fees.

Basis of Presentation - Reconci

Basis of Presentation - Reconciliation of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Weighted average basic shares outstanding (shares)	6,950	6,123	6,936	6,109
Potentially dilutive common shares related to:
Stock options (shares)	88	53	79	55
Unvested restricted stock awards (shares)	17	15	16	15
Weighted average diluted shares outstanding (shares)	7,055	6,191	7,031	6,179
Net income	$ 8,680	$ 5,132	$ 22,960	$ 14,866
Basic EPS (usd per share)	$ 1.25	$ 0.84	$ 3.31	$ 2.43
Diluted EPS (usd per share)	$ 1.23	$ 0.83	$ 3.27	$ 2.41
Weighted average anti-dilutive shares not included in the calculation of diluted EPS (shares)	0	23	1	19

Basis of Presentation - Summary

Basis of Presentation - Summary of Proforma EPS (Details)	Oct. 22, 2018	Sep. 30, 2018$ / shares	Sep. 30, 2017$ / shares	Sep. 30, 2018$ / shares	Sep. 30, 2017$ / shares
Subsequent Event [Line Items]
Basic EPS stock split proforma (usd per share)		$ 0.62	$ 0.42	$ 1.66	$ 1.22
Diluted EPS stock split proforma (usd per share)		$ 0.62	$ 0.41	$ 1.63	$ 1.20
Subsequent Event
Subsequent Event [Line Items]
Stock split, conversion ratio	2

Recently Adopted and Issued A_2

Recently Adopted and Issued Accounting Standards (Details) $ in Millions	Sep. 30, 2018USD ($)
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Undiscounted operating lease obligations, off-balance sheet	$ 15.4

Fair Value of Assets and Liab_3

Fair Value of Assets and Liabilities - Recorded on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 405,571	$ 332,467
SBA-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	40,181	25,982
Debentures of government- sponsored agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	42,914	12,938
Privately-issued collateralized mortgage obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	370	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	73,373	97,491
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	2,513	6,564
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)	436	74
Derivative financial liabilities (interest rate contracts)	163	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 | 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	246,220	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 | 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 | 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	40,181	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	0	165
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	42,914	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 | 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	370	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 | 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	73,373	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 | 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	2,513	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
Carrying Value | Assets and liabilities at fair value measured on a recurring basis | Interest rate contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial assets (interest rate contracts)	436	74
Derivative financial liabilities (interest rate contracts)	163	740
Carrying Value | Assets and liabilities at fair value measured on a recurring basis | Mortgage-backed securities and collateralized mortgage obligations issued by U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	246,220	188,061
Carrying Value | Assets and liabilities at fair value measured on a recurring basis | SBA-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	40,181	25,982
Carrying Value | Assets and liabilities at fair value measured on a recurring basis | Debentures of government- sponsored agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	42,914	12,938
Carrying Value | Assets and liabilities at fair value measured on a recurring basis | Privately-issued collateralized mortgage obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	370	1,431
Carrying Value | Assets and liabilities at fair value measured on a recurring basis | Obligations of state and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	73,373	97,491
Carrying Value | Assets and liabilities at fair value measured on a recurring basis | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 2,513	$ 6,564

Fair Value of Assets and Liab_4

Fair Value of Assets and Liabilities - Narrative (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2018USD ($)security	Dec. 31, 2017USD ($)security
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Write down of held to maturity securities | $	$ 0	$ 0
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value | $	$ 0	$ 0
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	0
U.S. government agency obligation collateralized by loans guaranteed by SBA program | Available-for-sale Securities | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of securities | security		1

Fair Value of Assets and Liab_5

Fair Value of Assets and Liabilities - Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financial assets (recorded at amortized cost)
Investment securities held-to-maturity	$ 158,106	$ 151,032
Carrying Amounts | Level 1
Financial assets (recorded at amortized cost)
Cash and cash equivalents	142,718	203,545
Carrying Amounts | Level 2
Financial assets (recorded at amortized cost)
Investment securities held-to-maturity	164,222	151,032
Interest receivable	7,366	7,501
Financial liabilities (recorded at amortized cost)
Time deposits	126,140	160,116
Interest payable	155	191
Carrying Amounts | Level 3
Financial assets (recorded at amortized cost)
Loans, net	1,713,054	1,663,246
Financial liabilities (recorded at amortized cost)
Subordinated debentures	5,831	5,739
Fair Value | Level 1
Financial assets (recorded at amortized cost)
Cash and cash equivalents	142,718	203,545
Fair Value | Level 2
Financial assets (recorded at amortized cost)
Investment securities held-to-maturity	158,106	151,032
Interest receivable	7,366	7,501
Financial liabilities (recorded at amortized cost)
Time deposits	124,796	159,540
Interest payable	155	191
Fair Value | Level 3
Financial assets (recorded at amortized cost)
Loans, net	1,683,109	1,650,198
Financial liabilities (recorded at amortized cost)
Subordinated debentures	$ 7,505	$ 5,118

Investment Securities - Amortiz

Investment Securities - Amortized Cost and Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	$ 164,222	$ 151,032
Held to maturity, Fair Value	158,106	151,032
Held-to-maturity, Gross Unrealized Gains	160	619
Held-to-maturity, Gross Unrealized Losses	(6,276)	(619)
Total	416,732	334,285
Available-for-sale, at fair value	405,571	332,467
Available-for-sale, Gross Unrealized Gains	88	574
Available-for-sale, Gross Unrealized Losses	(11,249)	(2,392)
Total investment securities, Amortized Cost	580,954	485,317
Total investment securities, Fair Value	563,677	483,499
Total investment securities, Gross Unrealized Gains	248	1,193
Total investment securities, Gross Unrealized Losses	(17,525)	(3,011)
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	91,237	100,376
Held to maturity, Fair Value	86,962	100,096
Held-to-maturity, Gross Unrealized Gains	0	234
Held-to-maturity, Gross Unrealized Losses	(4,275)	(514)
Total	93,096	65,559
Available-for-sale, at fair value	90,484	65,262
Available-for-sale, Gross Unrealized Gains	20	126
Available-for-sale, Gross Unrealized Losses	(2,632)	(423)
SBA-backed securities
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	8,723	0
Held to maturity, Fair Value	8,489	0
Held-to-maturity, Gross Unrealized Gains	0	0
Held-to-maturity, Gross Unrealized Losses	(234)	0
Total	41,074	25,979
Available-for-sale, at fair value	40,181	25,982
Available-for-sale, Gross Unrealized Gains	0	58
Available-for-sale, Gross Unrealized Losses	(893)	(55)
CMOs issued by FNMA
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	11,646	0
Held to maturity, Fair Value	11,254	0
Held-to-maturity, Gross Unrealized Gains	0	0
Held-to-maturity, Gross Unrealized Losses	(392)	0
Total	19,914	35,340
Available-for-sale, at fair value	19,356	35,125
Available-for-sale, Gross Unrealized Gains	4	33
Available-for-sale, Gross Unrealized Losses	(562)	(248)
CMOs issued by FHLMC
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	34,169	31,010
Held to maturity, Fair Value	32,868	30,938
Held-to-maturity, Gross Unrealized Gains	0	2
Held-to-maturity, Gross Unrealized Losses	(1,301)	(74)
Total	128,848	70,514
Available-for-sale, at fair value	124,930	69,889
Available-for-sale, Gross Unrealized Gains	1	3
Available-for-sale, Gross Unrealized Losses	(3,919)	(628)
CMOs issued by GNMA
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	3,734	0
Held to maturity, Fair Value	3,694	0
Held-to-maturity, Gross Unrealized Gains	0	0
Held-to-maturity, Gross Unrealized Losses	(40)	0
Total	11,938	17,953
Available-for-sale, at fair value	11,450	17,785
Available-for-sale, Gross Unrealized Gains	0	26
Available-for-sale, Gross Unrealized Losses	(488)	(194)
Debentures of government- sponsored agencies
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Total	43,470	12,940
Available-for-sale, at fair value	42,914	12,938
Available-for-sale, Gross Unrealized Gains	0	3
Available-for-sale, Gross Unrealized Losses	(556)	(5)
Privately issued CMOs
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Total	367	1,432
Available-for-sale, at fair value	370	1,431
Available-for-sale, Gross Unrealized Gains	3	1
Available-for-sale, Gross Unrealized Losses	0	(2)
Obligations of state and political subdivisions
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	14,713	19,646
Held to maturity, Fair Value	14,839	19,998
Held-to-maturity, Gross Unrealized Gains	160	383
Held-to-maturity, Gross Unrealized Losses	(34)	(31)
Total	75,519	98,027
Available-for-sale, at fair value	73,373	97,491
Available-for-sale, Gross Unrealized Gains	41	298
Available-for-sale, Gross Unrealized Losses	(2,187)	(834)
Corporate bonds
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Total	2,506	6,541
Available-for-sale, at fair value	2,513	6,564
Available-for-sale, Gross Unrealized Gains	19	26
Available-for-sale, Gross Unrealized Losses	$ (12)	$ (3)

Investment Securities - Maturit

Investment Securities - Maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Held-to-maturity Securities, Amortized Cost
Within one year	$ 2,677	$ 2,151
After one but within five years	12,476	15,577
After five years through ten years	60,422	54,641
After ten years	88,647	78,663
Total	164,222	151,032
Held-to-maturity Securities, Fair Value
Within one year	2,697	2,172
After one but within five years	12,438	15,791
After five years through ten years	58,041	54,554
After ten years	84,930	78,515
Total	158,106	151,032
Available-for-sale Securities, Amortized Cost
Within one year	10,111	10,268
After one but within five years	69,230	71,576
After five years through ten years	239,939	129,723
After ten years	97,452	122,718
Total	416,732	334,285
Available-for-sale Securities, Fair Value
Within one year	10,031	10,272
After one but within five years	67,972	71,237
After five years through ten years	232,532	128,954
After ten years	95,036	122,004
Total	$ 405,571	$ 332,467

Investment Securities - Sales o

Investment Securities - Sales of investment securities and gross gains and losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Available-for-sale:
Sales proceeds	$ 11,966	$ 0	$ 16,972	$ 1,321
Gross realized gains	0	0	27	13
Gross realized losses	$ (90)	$ 0	$ (106)	$ (3)

Investment Securities - Pledged

Investment Securities - Pledged and Transferred Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Public Deposits
Financial Instruments Owned and Pledged as Collateral [Line Items]
Available-for-sale securities pledged as collateral	$ 97,978	$ 107,829
Trust Deposits
Financial Instruments Owned and Pledged as Collateral [Line Items]
Available-for-sale securities pledged as collateral	740	761
State of California
Financial Instruments Owned and Pledged as Collateral [Line Items]
Available-for-sale securities pledged as collateral	98,718	108,590
Internal checking account
Financial Instruments Owned and Pledged as Collateral [Line Items]
Available-for-sale securities pledged as collateral	$ 2,005	$ 2,026

Investment Securities - Narrati

Investment Securities - Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018USD ($)security	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)security	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)security
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Securities transferred from available-for-sale to held-to-maturity | $			$ 27,422	$ 128,965	$ 129,000
Unrealized pre-tax loss from transfer of available-for-sale securities to held-to-maturity | $			278		3,000
Amortization of net unrealized losses on securities transferred from available-for-sale to held-to-maturity | $	$ 128	$ 135	$ 396	$ 299	$ 299
Number of investment securities in unrealized loss position | security	253		253		198
Number of investment securities in unrealized loss position longer than 12 months | security	83		83
Number of investment securities in unrealized loss position less than 12 months | security	170		170

Investment Securities - Unreali

Investment Securities - Unrealized Loss Positions (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 continuous months	$ 41,567	$ 31,051
Greater than or equal to 12 continuous months	105,492	60,669
Total Securities in a loss position	147,059	91,720
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 continuous months	(1,285)	(205)
Greater than or equal to 12 continuous months	(4,991)	(414)
Held-to-maturity, Gross Unrealized Losses	(6,276)	(619)
Debt Securities, Available-for-sale, Unrealized Loss Position [Abstract]
Available-for-sale, less than 12 continuous months, Fair value	270,513	212,675
Available-for-sale, greater than 12 continuous months, Fair value	78,041	40,478
Available-for-sale, Total Securities in a loss position, Fair Value	348,554	253,153
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Available-for-sale, less than 12 continuous months, Unrealized loss	(7,848)	(1,465)
Available-for-sale, greater than 12 continuous months, Unrealized loss	(3,401)	(927)
Available-for-sale, Total Securities in a loss position, Unrealized loss	(11,249)	(2,392)
Marketable Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Marketable securities, less than 12 continuous months, Fair value	312,080	243,726
Marketable securities, greater than 12 continuous months, Fair value	183,533	101,147
Marketable securities, Total Securities in a loss position, Fair value	495,613	344,873
Marketable Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract]
Marketable securities, less than 12 continuous months, Unrealized loss	(9,133)	(1,670)
Marketable securities, greater than 12 continuous months, Unrealized loss	(8,392)	(1,341)
Marketable securities, Total Securities in a loss position, Unrealized loss	(17,525)	(3,011)
MBS pass-through securities issued by FHLMC and FNMA
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 continuous months	6,602	16,337
Greater than or equal to 12 continuous months	80,360	46,845
Total Securities in a loss position	86,962	63,182
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 continuous months	(225)	(143)
Greater than or equal to 12 continuous months	(4,050)	(371)
Held-to-maturity, Gross Unrealized Losses	(4,275)	(514)
Debt Securities, Available-for-sale, Unrealized Loss Position [Abstract]
Available-for-sale, less than 12 continuous months, Fair value	52,821	32,189
Available-for-sale, greater than 12 continuous months, Fair value	20,406	15,325
Available-for-sale, Total Securities in a loss position, Fair Value	73,227	47,514
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Available-for-sale, less than 12 continuous months, Unrealized loss	(1,804)	(121)
Available-for-sale, greater than 12 continuous months, Unrealized loss	(828)	(302)
Available-for-sale, Total Securities in a loss position, Unrealized loss	(2,632)	(423)
SBA-backed securities
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 continuous months	8,489
Greater than or equal to 12 continuous months	0
Total Securities in a loss position	8,489
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 continuous months	(234)
Greater than or equal to 12 continuous months	0
Held-to-maturity, Gross Unrealized Losses	(234)
Debt Securities, Available-for-sale, Unrealized Loss Position [Abstract]
Available-for-sale, less than 12 continuous months, Fair value	23,162	11,028
Available-for-sale, greater than 12 continuous months, Fair value	0	165
Available-for-sale, Total Securities in a loss position, Fair Value	23,162	11,193
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Available-for-sale, less than 12 continuous months, Unrealized loss	(893)	(53)
Available-for-sale, greater than 12 continuous months, Unrealized loss	0	(2)
Available-for-sale, Total Securities in a loss position, Unrealized loss	(893)	(55)
CMOs issued by FNMA
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 continuous months	11,254
Greater than or equal to 12 continuous months	0
Total Securities in a loss position	11,254
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 continuous months	(392)
Greater than or equal to 12 continuous months	0
Held-to-maturity, Gross Unrealized Losses	(392)
Debt Securities, Available-for-sale, Unrealized Loss Position [Abstract]
Available-for-sale, less than 12 continuous months, Fair value	13,230	26,401
Available-for-sale, greater than 12 continuous months, Fair value	5,905	5,440
Available-for-sale, Total Securities in a loss position, Fair Value	19,135	31,841
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Available-for-sale, less than 12 continuous months, Unrealized loss	(383)	(171)
Available-for-sale, greater than 12 continuous months, Unrealized loss	(179)	(77)
Available-for-sale, Total Securities in a loss position, Unrealized loss	(562)	(248)
CMOs issued by FHLMC
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 continuous months	11,430	11,066
Greater than or equal to 12 continuous months	21,438	13,824
Total Securities in a loss position	32,868	24,890
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 continuous months	(400)	(31)
Greater than or equal to 12 continuous months	(901)	(43)
Held-to-maturity, Gross Unrealized Losses	(1,301)	(74)
Debt Securities, Available-for-sale, Unrealized Loss Position [Abstract]
Available-for-sale, less than 12 continuous months, Fair value	87,017	69,276
Available-for-sale, greater than 12 continuous months, Fair value	29,702	0
Available-for-sale, Total Securities in a loss position, Fair Value	116,719	69,276
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Available-for-sale, less than 12 continuous months, Unrealized loss	(2,930)	(628)
Available-for-sale, greater than 12 continuous months, Unrealized loss	(989)	0
Available-for-sale, Total Securities in a loss position, Unrealized loss	(3,919)	(628)
CMOs issued by GNMA
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 continuous months	0
Greater than or equal to 12 continuous months	3,694
Total Securities in a loss position	3,694
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 continuous months	0
Greater than or equal to 12 continuous months	(40)
Held-to-maturity, Gross Unrealized Losses	(40)
Debt Securities, Available-for-sale, Unrealized Loss Position [Abstract]
Available-for-sale, less than 12 continuous months, Fair value	10,728	14,230
Available-for-sale, greater than 12 continuous months, Fair value	485	0
Available-for-sale, Total Securities in a loss position, Fair Value	11,213	14,230
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Available-for-sale, less than 12 continuous months, Unrealized loss	(485)	(194)
Available-for-sale, greater than 12 continuous months, Unrealized loss	(3)	0
Available-for-sale, Total Securities in a loss position, Unrealized loss	(488)	(194)
Debentures of government- sponsored agencies
Debt Securities, Available-for-sale, Unrealized Loss Position [Abstract]
Available-for-sale, less than 12 continuous months, Fair value	37,831	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	37,831	2,984
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Available-for-sale, less than 12 continuous months, Unrealized loss	(556)	(5)
Available-for-sale, greater than 12 continuous months, Unrealized loss	0	0
Available-for-sale, Total Securities in a loss position, Unrealized loss	(556)	(5)
Privately issued CMOs
Debt Securities, Available-for-sale, Unrealized Loss Position [Abstract]
Available-for-sale, less than 12 continuous months, Fair value		1,310
Available-for-sale, greater than 12 continuous months, Fair value		0
Available-for-sale, Total Securities in a loss position, Fair Value		1,310
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Available-for-sale, less than 12 continuous months, Unrealized loss		(2)
Available-for-sale, greater than 12 continuous months, Unrealized loss		0
Available-for-sale, Total Securities in a loss position, Unrealized loss		(2)
Obligations of state and political subdivisions
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 continuous months	3,792	3,648
Greater than or equal to 12 continuous months	0	0
Total Securities in a loss position	3,792	3,648
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss [Abstract]
Less than 12 continuous months	(34)	(31)
Greater than or equal to 12 continuous months	0	0
Held-to-maturity, Gross Unrealized Losses	(34)	(31)
Debt Securities, Available-for-sale, Unrealized Loss Position [Abstract]
Available-for-sale, less than 12 continuous months, Fair value	44,714	52,197
Available-for-sale, greater than 12 continuous months, Fair value	21,543	19,548
Available-for-sale, Total Securities in a loss position, Fair Value	66,257	71,745
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Available-for-sale, less than 12 continuous months, Unrealized loss	(785)	(288)
Available-for-sale, greater than 12 continuous months, Unrealized loss	(1,402)	(546)
Available-for-sale, Total Securities in a loss position, Unrealized loss	(2,187)	(834)
Corporate bonds
Debt Securities, Available-for-sale, Unrealized Loss Position [Abstract]
Available-for-sale, less than 12 continuous months, Fair value	1,010	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	1,010	3,060
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Available-for-sale, less than 12 continuous months, Unrealized loss	(12)	(3)
Available-for-sale, greater than 12 continuous months, Unrealized loss	0	0
Available-for-sale, Total Securities in a loss position, Unrealized loss	$ (12)	$ (3)

Investment Securities - Non-Mar

Investment Securities - Non-Marketable Securities (Details)	Oct. 25, 2018USD ($)shares	Oct. 22, 2018	Sep. 30, 2018USD ($)$ / sharesshares	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)$ / sharesshares	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Schedule of Equity Method Investments [Line Items]
Federal Home Loan Bank stock, par value (usd per share) | $ / shares			$ 100		$ 100
Investments in low income housing tax credit funds			$ 4,800,000		$ 4,800,000		$ 2,100,000
Low income housing tax credits and other tax benefits			173,000		454,000
Low income housing amortization expense			144,000		381,000
Unfunded commitments for low income housing tax credit funds			$ 3,200,000		$ 3,200,000
Visa Inc. Class B common stock
Schedule of Equity Method Investments [Line Items]
Number of shares of securities carried at cost (in shares) | shares			16,939		16,939
Carrying value of securities carried at cost			$ 0		$ 0
Fair value of Class B common stock			4,100,000		$ 4,100,000		$ 3,200,000
Visa Inc. | Visa Inc. Class B common stock
Schedule of Equity Method Investments [Line Items]
Conversion rate on common stock					1.6298		1.6483
Other assets
Schedule of Equity Method Investments [Line Items]
Federal Home Loan Bank stock			11,100,000		$ 11,100,000		$ 11,100,000
Low-Income Housing Tax Credit Investment
Schedule of Equity Method Investments [Line Items]
Impairment losses			$ 0	$ 0	$ 0	$ 0
Subsequent Event
Schedule of Equity Method Investments [Line Items]
Federal Home Loan Bank, dividend rate percentage	7.00%
Conversion rate on common stock		2
Subsequent Event | Visa Inc. Class B common stock
Schedule of Equity Method Investments [Line Items]
Number of shares sold during the period (in shares) | shares	6,500
Scenario, Forecast | Visa Inc. Class B common stock
Schedule of Equity Method Investments [Line Items]
Estimated net pre-tax gain from sale of Visa class B common stock	$ 955,000

Loans and Allowance for Loan _3

Loans and Allowance for Loan Losses - Outstanding and Aging Analysis (Details)	12 Months Ended
	Dec. 31, 2017USD ($)loan	Sep. 30, 2018USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	$ 2,331,000	$ 301,000
Current	1,676,682,000	1,728,570,000
Total loans	1,679,013,000	1,728,871,000
Non-accrual	$ 406,000	386,000
Number of purchase credit impaired (PCI) loans with unpaid balances | loan	3
Unpaid balances on purchase credit impaired (PCI) loans	$ 131,000	0
Purchased Credit Impaired (PCI) loans no longer accreting interest	0
Purchased Credit-impaired (PCI) loans accreting interest	2,100,000	2,100,000
Loans past due more than 90 days still accruing	0	0
Deferred loan fees	818,000	704,000
Unaccreted purchase discounts on non-PCI loans	1,200,000	922,000
30-59 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	684,000	234,000
60-89 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	1,340,000	67,000
90 days or more past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	307,000	0
Commercial loans | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	1,340,000	20,000
Current	234,495,000	238,751,000
Total loans	235,835,000	238,771,000
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	1,340,000	20,000
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	300,963,000	316,467,000
Total loans	300,963,000	316,467,000
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	822,984,000	841,493,000
Total loans	822,984,000	841,493,000
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	63,828,000	68,739,000
Total loans	63,828,000	68,739,000
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	406,000	121,000
Current	132,061,000	121,122,000
Total loans	132,467,000	121,243,000
Non-accrual	406,000	318,000
Residential loans | Home equity | 30-59 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	99,000	121,000
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	307,000	0
Residential loans | Other residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	255,000	0
Current	95,271,000	113,383,000
Total loans	95,526,000	113,383,000
Non-accrual	0	0
Residential loans | Other residential | 30-59 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	255,000	0
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	330,000	160,000
Current	27,080,000	28,615,000
Total loans	27,410,000	28,775,000
Non-accrual	0	68,000
Consumer loans | Installment and other consumer | 30-59 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	330,000	113,000
Consumer loans | Installment and other consumer | 60-89 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due	0	47,000
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 _4

Loans and Allowance for Loan Losses - Credit Quality (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Total loans	$ 1,728,871	$ 1,679,013
Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,693,389	1,629,865
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	23,081	21,242
Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	12,401	27,906
Purchased credit-impaired
Financing Receivable, Recorded Investment [Line Items]
Purchased credit-impaired	2,129	2,115
Purchased credit-impaired | Pass
Financing Receivable, Recorded Investment [Line Items]
Purchased credit-impaired	2,129	1,325
Purchased credit-impaired | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Purchased credit-impaired	0	790
Purchased credit-impaired | Substandard
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	238,732	235,770
Total loans	238,771	235,835
Commercial loans | Commercial and industrial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	223,259	214,636
Commercial loans | Commercial and industrial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	14,574	9,318
Commercial loans | Commercial and industrial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	899	11,816
Commercial loans | Purchased credit-impaired | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Purchased credit-impaired	39	65
Commercial real estate loans | Commercial real estate, owner-occupied
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	315,269	299,797
Total loans	316,467	300,963
Commercial real estate loans | Commercial real estate, owner-occupied | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	302,082	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	5,192	9,284
Commercial real estate loans | Commercial real estate, owner-occupied | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	7,995	9,409
Commercial real estate loans | Commercial real estate, investor
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	840,687	822,194
Total loans	841,493	822,984
Commercial real estate loans | Commercial real estate, investor | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	838,493	818,570
Commercial real estate loans | Commercial real estate, investor | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	2,194	1,850
Commercial real estate loans | Commercial real estate, investor | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	0	1,774
Commercial real estate loans | Construction
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	68,739	63,828
Total loans	68,739	63,828
Commercial real estate loans | Construction | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	66,049	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	2,690	2,969
Commercial real estate loans | Purchased credit-impaired | Commercial real estate, owner-occupied
Financing Receivable, Recorded Investment [Line Items]
Purchased credit-impaired	1,198	1,166
Commercial real estate loans | Purchased credit-impaired | Commercial real estate, investor
Financing Receivable, Recorded Investment [Line Items]
Purchased credit-impaired	806	790
Commercial real estate loans | Purchased credit-impaired | Construction
Financing Receivable, Recorded Investment [Line Items]
Purchased credit-impaired	0	0
Residential loans | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	121,157	132,373
Total loans	121,243	132,467
Residential loans | Home equity | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	119,383	130,558
Residential loans | Home equity | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	1,121	0
Residential loans | Home equity | Substandard
Financing Receivable, Recorded Investment [Line Items]
Loans excluding purchased credit-impaired loans	653	1,815
Residential loans | Other residential
Financing Receivable, Recorded Investment [Line Items]
Total loans	113,383	95,526
Residential loans | Other residential | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	113,383	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
Residential loans | Purchased credit-impaired | Home equity
Financing Receivable, Recorded Investment [Line Items]
Purchased credit-impaired	86	94
Residential loans | Purchased credit-impaired | Other residential
Financing Receivable, Recorded Investment [Line Items]
Purchased credit-impaired	0	0
Consumer loans | Installment and other consumer
Financing Receivable, Recorded Investment [Line Items]
Total loans	28,775	27,410
Consumer loans | Installment and other consumer | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	28,611	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	164	123
Consumer loans | Purchased credit-impaired | Installment and other consumer
Financing Receivable, Recorded Investment [Line Items]
Purchased credit-impaired	$ 0	$ 0

Loans and Allowance for Loan _5

Loans and Allowance for Loan Losses - Troubled Debt Restructuring by Class (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2018USD ($)loan	Dec. 31, 2017USD ($)loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans removed from TDR designation | loan		0
Recorded investment of loans removed from TDR resignation	$ 247,000
Recorded investment in Troubled Debt Restructurings	$ 15,213,000	$ 16,520,000
TDR loans on non-accrual status, quantity | loan	2
TDR loans on non-accrual status	$ 68,000	$ 0
Acquired loans on TDR status | loan	0	0
Commercial loans | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in Troubled Debt Restructurings	$ 1,763,000	$ 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	6,997,000	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	1,831,000	2,171,000
Commercial real estate loans | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in Troubled Debt Restructurings	$ 2,690,000	2,969,000
Residential loans | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans removed from TDR designation | loan	1
Recorded investment in Troubled Debt Restructurings	$ 251,000	347,000
Residential loans | Other residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans removed from TDR designation | loan	1
Recorded investment in Troubled Debt Restructurings	$ 986,000	1,148,000
Consumer loans | Installment and other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in Troubled Debt Restructurings	$ 695,000	$ 721,000

Loans and Allowance for Loan _6

Loans and Allowance for Loan Losses - Troubled Debt Restructuring Modifications (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)contract	Sep. 30, 2017USD ($)contract	Sep. 30, 2018USD ($)contractloan	Sep. 30, 2017USD ($)contractloan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts Modified | contract	0	0
Pre-Modification Outstanding Recorded Investment	$ 0	$ 0
Post-Modification Outstanding Recorded Investment	0	0
Post-Modification Outstanding Recorded Investment at Period End	$ 0	$ 0
Number of modified TDR loans that defaulted | loan			0	0
Commercial loans | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts Modified | contract			2
Pre-Modification Outstanding Recorded Investment			$ 254
Post-Modification Outstanding Recorded Investment			245
Post-Modification Outstanding Recorded Investment at Period End			$ 235
Consumer loans | Installment and other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts Modified | contract				1
Pre-Modification Outstanding Recorded Investment				$ 50
Post-Modification Outstanding Recorded Investment				50
Post-Modification Outstanding Recorded Investment at Period End				$ 49

Loans and Allowance for Loan _7

Loans and Allowance for Loan Losses - Impaired and Related Allowance (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Recorded investment in impaired loans:
With no specific allowance recorded	$ 4,411,000		$ 4,411,000		$ 4,445,000
With a specific allowance recorded	11,120,000		11,120,000		12,481,000
Total recorded investment in impaired loans	15,531,000		15,531,000		16,926,000
Unpaid principal balance of impaired loans	15,502,000		15,502,000		17,019,000
Specific allowance	527,000		527,000		513,000
Average recorded investment in impaired loans during the period	15,705,000	$ 17,976,000	16,212,000	$ 18,180,000
Interest income recognized on impaired loans during the period ended	182,000	183,000	665,000	544,000
Interest income recognized on impaired loans during the period ended, cash basis	6,000	0	134,000	0
Charge-off amounts on impaired loans			0		0
Outstanding commitments to extend credit on impaired loans	950,000		950,000		935,000
Commercial loans | Commercial and industrial
Recorded investment in impaired loans:
With no specific allowance recorded	304,000		304,000		309,000
With a specific allowance recorded	1,459,000		1,459,000		1,856,000
Total recorded investment in impaired loans	1,763,000		1,763,000		2,165,000
Unpaid principal balance of impaired loans	1,751,000		1,751,000		2,278,000
Specific allowance	173,000		173,000		50,000
Average recorded investment in impaired loans during the period	1,840,000	2,063,000	2,019,000	2,100,000
Interest income recognized on impaired loans during the period ended	31,000	27,000	214,000	74,000
Commercial real estate loans | Commercial real estate, owner-occupied
Recorded investment in impaired loans:
With no specific allowance recorded	0		0		0
With a specific allowance recorded	6,997,000		6,997,000		6,999,000
Total recorded investment in impaired loans	6,997,000		6,997,000		6,999,000
Unpaid principal balance of impaired loans	6,993,000		6,993,000		6,993,000
Specific allowance	228,000		228,000		188,000
Average recorded investment in impaired loans during the period	7,000,000	7,000,000	7,002,000	6,998,000
Interest income recognized on impaired loans during the period ended	67,000	67,000	199,000	199,000
Commercial real estate loans | Commercial real estate, investor
Recorded investment in impaired loans:
With no specific allowance recorded	0		0		0
With a specific allowance recorded	1,831,000		1,831,000		2,171,000
Total recorded investment in impaired loans	1,831,000		1,831,000		2,171,000
Unpaid principal balance of impaired loans	1,824,000		1,824,000		2,168,000
Specific allowance	44,000		44,000		159,000
Average recorded investment in impaired loans during the period	1,837,000	3,236,000	1,925,000	3,010,000
Interest income recognized on impaired loans during the period ended	20,000	22,000	63,000	65,000
Commercial real estate loans | Construction
Recorded investment in impaired loans:
With no specific allowance recorded	2,690,000		2,690,000		2,689,000
With a specific allowance recorded	0		0		280,000
Total recorded investment in impaired loans	2,690,000		2,690,000		2,969,000
Unpaid principal balance of impaired loans	2,688,000		2,688,000		2,963,000
Specific allowance	0		0		7,000
Average recorded investment in impaired loans during the period	2,690,000	3,104,000	2,831,000	3,174,000
Interest income recognized on impaired loans during the period ended	39,000	39,000	114,000	110,000
Residential loans | Home equity
Recorded investment in impaired loans:
With no specific allowance recorded	318,000		318,000		406,000
With a specific allowance recorded	251,000		251,000		347,000
Total recorded investment in impaired loans	569,000		569,000		753,000
Unpaid principal balance of impaired loans	567,000		567,000		750,000
Specific allowance	5,000		5,000		6,000
Average recorded investment in impaired loans during the period	651,000	607,000	698,000	660,000
Interest income recognized on impaired loans during the period ended	5,000	5,000	15,000	19,000
Residential loans | Other residential
Recorded investment in impaired loans:
With no specific allowance recorded	986,000		986,000		995,000
With a specific allowance recorded	0		0		153,000
Total recorded investment in impaired loans	986,000		986,000		1,148,000
Unpaid principal balance of impaired loans	985,000		985,000		1,147,000
Specific allowance	0		0		1,000
Average recorded investment in impaired loans during the period	987,000	1,164,000	1,029,000	1,367,000
Interest income recognized on impaired loans during the period ended	13,000	14,000	38,000	48,000
Consumer loans | Installment and other consumer
Recorded investment in impaired loans:
With no specific allowance recorded	113,000		113,000		46,000
With a specific allowance recorded	582,000		582,000		675,000
Total recorded investment in impaired loans	695,000		695,000		721,000
Unpaid principal balance of impaired loans	694,000		694,000		720,000
Specific allowance	77,000		77,000		$ 102,000
Average recorded investment in impaired loans during the period	700,000	802,000	708,000	871,000
Interest income recognized on impaired loans during the period ended	$ 7,000	$ 9,000	$ 22,000	$ 29,000

Loans and Allowance for Loan _8

Loans and Allowance for Loan Losses - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Allowance for loan losses:
Beginning balance	$ 15,813	$ 15,232	$ 15,767	$ 15,442
Provision for loan losses	0	0	0	0
Charge-offs	0	(6)	(5)	(292)
Recoveries	4	22	55	98
Ending balance	15,817	15,248	15,817	15,248
Ending ALLL related to loans collectively evaluated for impairment	15,290		15,290		$ 15,254
Ending ALLL related to loans individually evaluated for impairment	527		527		513
Ending ALLL	15,817		15,817		15,767
Collectively evaluated for impairment	1,711,211		1,711,211		1,659,972
Individually evaluated for impairment	15,531		15,531		16,926
Total loans	$ 1,728,871		$ 1,728,871		$ 1,679,013
Ratio of allowance for loan losses to total loans	0.91%		0.91%		0.94%
Allowance for loan losses to non-accrual loans	4098.00%		4098.00%		3883.00%
Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0		$ 0
Purchased credit-impaired	2,129		2,129		2,115
Commercial loans | Commercial and industrial
Allowance for loan losses:
Beginning balance	2,597	3,932	3,654	3,248
Provision for loan losses	(245)	612	(1,308)	1,509
Charge-offs	0	(5)	(3)	(289)
Recoveries	4	21	13	92
Ending balance	2,356	4,560	2,356	4,560
Ending ALLL related to loans collectively evaluated for impairment	2,183		2,183		3,604
Ending ALLL related to loans individually evaluated for impairment	173		173		50
Ending ALLL	2,356		2,356		3,654
Collectively evaluated for impairment	236,969		236,969		233,605
Individually evaluated for impairment	1,763		1,763		2,165
Total loans	$ 238,771		$ 238,771		$ 235,835
Ratio of allowance for loan losses to total loans	0.99%		0.99%		1.55%
Commercial loans | Commercial and industrial | Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0		$ 0
Purchased credit-impaired	39		39		65
Commercial real estate loans | Commercial real estate, owner-occupied
Allowance for loan losses:
Beginning balance	2,339	2,082	2,294	1,753
Provision for loan losses	83	(56)	128	273
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	2,422	2,026	2,422	2,026
Ending ALLL related to loans collectively evaluated for impairment	2,194		2,194		2,106
Ending ALLL related to loans individually evaluated for impairment	228		228		188
Ending ALLL	2,422		2,422		2,294
Collectively evaluated for impairment	308,272		308,272		292,798
Individually evaluated for impairment	6,997		6,997		6,999
Total loans	$ 316,467		$ 316,467		$ 300,963
Ratio of allowance for loan losses to total loans	0.77%		0.77%		0.76%
Commercial real estate loans | Commercial real estate, owner-occupied | Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0		$ 0
Purchased credit-impaired	1,198		1,198		1,166
Commercial real estate loans | Commercial real estate, investor
Allowance for loan losses:
Beginning balance	7,390	6,065	6,475	6,320
Provision for loan losses	46	33	961	(222)
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	7,436	6,098	7,436	6,098
Ending ALLL related to loans collectively evaluated for impairment	7,392		7,392		6,316
Ending ALLL related to loans individually evaluated for impairment	44		44		159
Ending ALLL	7,436		7,436		6,475
Collectively evaluated for impairment	838,856		838,856		820,023
Individually evaluated for impairment	1,831		1,831		2,171
Total loans	$ 841,493		$ 841,493		$ 822,984
Ratio of allowance for loan losses to total loans	0.88%		0.88%		0.79%
Commercial real estate loans | Commercial real estate, investor | Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0		$ 0
Purchased credit-impaired	806		806		790
Commercial real estate loans | Construction
Allowance for loan losses:
Beginning balance	508	411	681	781
Provision for loan losses	157	217	(16)	(153)
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	665	628	665	628
Ending ALLL related to loans collectively evaluated for impairment	665		665		674
Ending ALLL related to loans individually evaluated for impairment	0		0		7
Ending ALLL	665		665		681
Collectively evaluated for impairment	66,049		66,049		60,859
Individually evaluated for impairment	2,690		2,690		2,969
Total loans	$ 68,739		$ 68,739		$ 63,828
Ratio of allowance for loan losses to total loans	0.97%		0.97%		1.07%
Commercial real estate loans | Construction | Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0		$ 0
Purchased credit-impaired	0		0		0
Residential loans | Home equity
Allowance for loan losses:
Beginning balance	952	981	1,031	973
Provision for loan losses	(39)	21	(118)	29
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	913	1,002	913	1,002
Ending ALLL related to loans collectively evaluated for impairment	908		908		1,025
Ending ALLL related to loans individually evaluated for impairment	5		5		6
Ending ALLL	913		913		1,031
Collectively evaluated for impairment	120,588		120,588		131,620
Individually evaluated for impairment	569		569		753
Total loans	$ 121,243		$ 121,243		$ 132,467
Ratio of allowance for loan losses to total loans	0.75%		0.75%		0.78%
Allowance for loan losses to non-accrual loans	287.00%		287.00%		254.00%
Residential loans | Home equity | Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0		$ 0
Purchased credit-impaired	86		86		94
Residential loans | Other residential
Allowance for loan losses:
Beginning balance	746	509	536	454
Provision for loan losses	35	33	245	88
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	781	542	781	542
Ending ALLL related to loans collectively evaluated for impairment	781		781		535
Ending ALLL related to loans individually evaluated for impairment	0		0		1
Ending ALLL	781		781		536
Collectively evaluated for impairment	112,397		112,397		94,378
Individually evaluated for impairment	986		986		1,148
Total loans	$ 113,383		$ 113,383		$ 95,526
Ratio of allowance for loan losses to total loans	0.69%		0.69%		0.56%
Residential loans | Other residential | Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0		$ 0
Purchased credit-impaired	0		0		0
Consumer loans | Installment and other consumer
Allowance for loan losses:
Beginning balance	325	340	378	372
Provision for loan losses	5	(5)	(88)	(40)
Charge-offs	0	(1)	(2)	(3)
Recoveries	0	1	42	6
Ending balance	330	335	330	335
Ending ALLL related to loans collectively evaluated for impairment	253		253		276
Ending ALLL related to loans individually evaluated for impairment	77		77		102
Ending ALLL	330		330		378
Collectively evaluated for impairment	28,080		28,080		26,689
Individually evaluated for impairment	695		695		721
Total loans	$ 28,775		$ 28,775		$ 27,410
Ratio of allowance for loan losses to total loans	1.15%		1.15%		1.38%
Allowance for loan losses to non-accrual loans	485.00%		485.00%
Consumer loans | Installment and other consumer | Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	$ 0		$ 0		$ 0
Purchased credit-impaired	0		0		0
Unallocated
Allowance for loan losses:
Beginning balance	956	912	718	1,541
Provision for loan losses	(42)	(855)	196	(1,484)
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	914	$ 57	914	$ 57
Ending ALLL related to loans collectively evaluated for impairment	914		914		718
Ending ALLL related to loans individually evaluated for impairment	0		0		0
Ending ALLL	914		914		718
Collectively evaluated for impairment	0		0		0
Individually evaluated for impairment	0		0		0
Total loans	0		0		0
Unallocated | Purchased credit-impaired
Allowance for loan losses:
Ending ALLL	0		0		0
Purchased credit-impaired	$ 0		$ 0		$ 0

Loans and Allowance for Loan _9

Loans and Allowance for Loan Losses - Purchased Credit-Impaired (Details) $ in Thousands	3 Months Ended		9 Months Ended		81 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Nov. 21, 2017acquisition	Dec. 31, 2017USD ($)
Business Acquisitions, Purchased Credit-Impaired Loans [Line Items]
Number of banks acquired | acquisition					3
PCI Loans, Carrying Value [Abstract]
Unpaid Principal Balance	$ 2,621		$ 2,621			$ 2,868
Carrying Value	2,129		2,129			2,115
Accretable Yield [Roll Forward]
Balance at beginning of period	1,059	$ 1,306	1,254	$ 1,476
Accretion	(63)	(76)	(258)	(246)
Balance at end of period	996	$ 1,230	996	$ 1,230
Commercial loans | Commercial and industrial
PCI Loans, Carrying Value [Abstract]
Unpaid Principal Balance	106		106			276
Carrying Value	39		39			65
Commercial real estate loans | Commercial real estate, owner-occupied
PCI Loans, Carrying Value [Abstract]
Unpaid Principal Balance	1,259		1,259			1,297
Carrying Value	1,198		1,198			1,166
Commercial real estate loans | Commercial real estate, investor
PCI Loans, Carrying Value [Abstract]
Unpaid Principal Balance	1,041		1,041			1,064
Carrying Value	806		806			790
Residential loans | Home equity
PCI Loans, Carrying Value [Abstract]
Unpaid Principal Balance	215		215			231
Carrying Value	$ 86		$ 86			$ 94

Loans and Allowance for Loan_10

Loans and Allowance for Loan Losses - Pledged Loans (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Financial Instruments Owned and Pledged as Collateral [Line Items]
Residential loans pledged for FRB borrowings	$ 1,031.5	$ 887.9
Other residential
Financial Instruments Owned and Pledged as Collateral [Line Items]
Pledged residential loan portfolio to secure borrowing with FRB	$ 85.2	$ 67.6

Loans and Allowance for Loan_11

Loans and Allowance for Loan Losses - Related Party (Details) - USD ($) $ in Millions	Sep. 30, 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	$ 9.1	$ 9.1

Borrowings - Lines of Credit (D

Borrowings - Lines of Credit (Details) - Line of credit - USD ($)	Sep. 30, 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	616,200,000	538,900,000
Federal Home Loan Bank Overnight Borrowings
Line of Credit Facility [Line Items]
Amount of borrowings outstanding	0	0
Federal Reserve Line of Credit
Line of Credit Facility [Line Items]
Lines of credit	64,400,000	52,100,000
Amount of borrowings outstanding	0	0
Unsecured Debt | Federal Funds Purchased
Line of Credit Facility [Line Items]
Lines of credit	$ 92,000,000	$ 100,400,000

Borrowings - Subordinated Debt

Borrowings - Subordinated Debt (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)debenture	Sep. 30, 2017USD ($)
Debt Instrument [Line Items]
Accretion of discount on subordinated debentures		$ 92	$ 117
Amount guaranteed, on subordinated basis, distributions and other payments on trust preferred securities		$ 8,000
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		$ 92	$ 117
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		5.39%
Subordinated debenture | NorCal Community Bancorp Trust II
Debt Instrument [Line Items]
Contractual value of subordinated debt		$ 4,124
Effective interest rate		3.73%
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%
Subsequent Event | Subordinated debenture | NorCal Community Bancorp Trust I
Debt Instrument [Line Items]
Accretion of discount on subordinated debentures	$ 916

Stockholders' Equity (Details)

Stockholders' Equity (Details)	Oct. 22, 2018$ / shares	Sep. 30, 2018USD ($)shares	Mar. 31, 2018USD ($)	Sep. 30, 2018USD ($)$ / sharesshares	Sep. 30, 2017USD ($)$ / sharesshares	Apr. 20, 2018USD ($)
Class of Stock [Line Items]
Shares withheld for tax withholding and exercise of options (in shares) | shares				20,981	11,938
Amount of shares withheld for tax withholding and exercise of options				$ 1,500,000	$ 782,000
Shares withheld for tax withholding and exercise of options, weighted average price (usd per share) | $ / shares				$ 71.35	$ 65.50
Reclassification from AOCI to retained earnings for stranded income tax effects				$ 0
Share Repurchase Program, amount approved to repurchase						$ 25,000,000
Stock repurchased, net of commissions		$ 1,435,000		$ 1,539,000
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%
Retained Earnings
Class of Stock [Line Items]
Reclassification from AOCI to retained earnings for stranded income tax effects			$ 638,000	$ 638,000
Common Stock
Class of Stock [Line Items]
Stock repurchased, net of commissions (in shares) | shares		16,545		17,943
Stock repurchased, net of commissions		$ 1,435,000		$ 1,539,000
Subsequent Event
Class of Stock [Line Items]
Dividends declared per common share (usd per share) | $ / shares	$ 0.35
Stock split, conversion ratio	2

Commitments and Contingencies_2

Commitments and Contingencies (Details) - USD ($) $ in Thousands	Jun. 28, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2012	Dec. 31, 2017
Operating Leases
2,018		$ 1,106		$ 1,106
2,019		4,198		4,198
2,020		3,758		3,758
2,021		2,138		2,138
2,022		1,330		1,330
Thereafter		2,904		2,904
Total		15,400		15,400
Rent expense		1,100	$ 997	3,500	$ 3,000
Visa Inc.
Litigation Matters
Settlement agreement amount						$ 4,000,000
Litigation escrow deposit	$ 600,000
Balance of escrow account for legal settlements		1,500,000		1,500,000
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		483,328		483,328			$ 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			958
Commercial lines of credit
Loss Contingencies [Line Items]
Loan commitments and standby letters of credit, off-balance sheet		228,932		228,932			224,370
Revolving home equity lines
Loss Contingencies [Line Items]
Loan commitments and standby letters of credit, off-balance sheet		189,353		189,353			177,678
Undisbursed construction loans
Loss Contingencies [Line Items]
Loan commitments and standby letters of credit, off-balance sheet		51,624		51,624			35,322
Personal and other lines of credit
Loss Contingencies [Line Items]
Loan commitments and standby letters of credit, off-balance sheet		10,783		10,783			11,758
Standby letters of credit
Loss Contingencies [Line Items]
Loan commitments and standby letters of credit, off-balance sheet		$ 2,636		$ 2,636			$ 4,074

Derivative Financial Instrume_3

Derivative Financial Instruments and Hedging Activities - Information on Derivatives (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)derivative	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)derivative	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Derivatives, Fair Value [Line Items]
Carrying Amounts of Hedged Assets	$ 17,651		$ 17,651
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Loans	(493)		(493)
Fair value hedge | Interest income
Derivatives, Fair Value [Line Items]
Increase in value of designated interest rate swaps	222	$ 25	939	$ 7
Payment on interest rate swaps	(32)	(76)	(127)	(261)
Decrease in value of hedged loans	(231)	(43)	(924)	35
Decrease in value of yield maintenance agreement	(4)	(4)	(11)	(11)
Net loss on derivatives recognized against interest income	(45)	$ (98)	(123)	$ (230)
Fair value hedge | Designated as hedging instrument
Derivatives, Fair Value [Line Items]
Accrued interest on swaps	$ 4		$ 4		$ 8
Fair value hedge | Designated as hedging instrument | Interest rate swap
Derivatives, Fair Value [Line Items]
Number of derivative instruments | derivative	5		5
Fair value hedge | Designated as hedging instrument | Interest rate swap | Other assets
Derivatives, Fair Value [Line Items]
Interest rate contracts notional amount, asset derivatives	$ 8,988		$ 8,988		4,019
Fair value hedge | Designated as hedging instrument | Interest rate swap | Other liabilities
Derivatives, Fair Value [Line Items]
Interest rate contracts notional amount, liability derivatives	9,156		9,156		14,810
Fair value hedge | Designated as hedging instrument | Interest rate contract | Other assets
Derivatives, Fair Value [Line Items]
Interest rate contracts fair value, asset derivatives	436		436		74
Fair value hedge | Designated as hedging instrument | Interest rate contract | Other liabilities
Derivatives, Fair Value [Line Items]
Interest rate contracts fair value, liability derivatives	$ 163		$ 163		$ 740

Derivative Financial Instrume_4

Derivative Financial Instruments and Hedging Activities - Offsetting of Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Interest rate swap | Other assets
Offsetting Assets [Line Items]
Accrued interest on derivative asset interest rate swaps	$ 1	$ 1
Counterparty A
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets	436	74
Gross Amounts Offset in the Statements of Condition	0	0
Net Amounts of Assets Presented in the Statements of Condition	436	74
Gross Amounts Not Offset in the Statements of Condition, Financial Instruments	(163)	(74)
Gross Amounts Not Offset in the Statements of Condition, Cash Collateral Received	0	0
Net Amount	$ 273	$ 0

Derivative Financial Instrume_5

Derivative Financial Instruments and Hedging Activities - Offsetting of Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Interest rate swap | Other liabilities
Offsetting Liabilities [Line Items]
Accrued interest on derivative liability interest swaps	$ 3	$ 8
Counterparty A
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	163	740
Gross Amounts Offset in the Statements of Condition	0	0
Net Amounts of Liabilities Presented in the Statements of Condition	163	740
Gross Amounts Not Offset in the Statements of Condition, Financial Instruments	(163)	(74)
Gross Amounts Not Offset in the Statements of Condition, Cash Collateral Pledged		(666)
Net Amount	$ 0	$ 0

Acquisition - Narrative (Detail

Acquisition - Narrative (Details)	9 Months Ended		12 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)	Nov. 21, 2017USD ($)branch
Business Acquisition [Line Items]
Goodwill	$ 30,140,000		$ 30,140,000
Amortization of core deposit intangible	690,000	$ 354,000
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
Goodwill impairment	0
Core deposits | Bank of Napa, N.A. (Napa)
Business Acquisition [Line Items]
Core deposit intangible asset				$ 4,400,000
Amortization of core deposit intangible	$ 381,000		$ 56,000
Useful life of core deposit intangible asset	10 years

Acquisition - Summary of Acquis

Acquisition - Summary of Acquisition Related Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Business Acquisition [Line Items]
Data processing	$ 950	$ 946	$ 3,354	$ 2,848
Professional services	727	801	2,836	1,845
Other expense	1,628	1,471	4,989	4,716
Bank of Napa, N.A. (Napa)
Business Acquisition [Line Items]
Data processing	43	0	598	0
Professional services	46	449	172	458
Personnel severance	0	0	141	0
Other expense	0	46	43	46
Total	$ 89	$ 495	$ 954	$ 504