Enterprise Bancorp (EBTC) 10-Q 8 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	May 02, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	ENTERPRISE BANCORP INC /MA/
Entity Central Index Key	1,018,399
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		11,682,613

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Cash and cash equivalents:
Cash and due from banks	$ 34,703	$ 40,310
Interest-earning deposits	22,175	14,496
Total cash and cash equivalents	56,878	54,806
Investment securities at fair value	412,508	405,206
Federal Home Loan Bank stock	2,370	5,215
Loans held for sale	0	208
Loans, less allowance for loan losses of $34,524 at March 31, 2018, and $32,915 at December 31, 2017	2,255,649	2,236,989
Premises and equipment, net	37,212	37,022
Accrued interest receivable	11,210	10,614
Deferred income taxes, net	12,858	10,751
Bank-owned life insurance	29,634	29,466
Prepaid income taxes	0	1,301
Prepaid expenses and other assets	10,953	20,330
Goodwill	5,656	5,656
Total assets	2,834,928	2,817,564
Liabilities
Deposits	2,571,389	2,441,362
Borrowed funds	0	89,000
Subordinated debt	14,850	14,847
Accrued expenses and other liabilities	16,400	40,067
Income taxes payable	53	0
Accrued interest payable	596	478
Total liabilities	2,603,288	2,585,754
Commitments and Contingencies
Stockholders' Equity
Preferred stock, $0.01 par value per share; 1,000,000 shares authorized; no shares issued	0	0
Common stock, $0.01 par value per share; 40,000,000 shares authorized; 11,682,914 shares issued and outstanding at March 31, 2018, and 11,609,853 shares issued and outstanding at December 31, 2017	117	116
Additional paid-in capital	89,159	88,205
Retained earnings	148,212	143,073
Accumulated other comprehensive (loss) income	(5,848)	416
Total stockholders' equity	231,640	231,810
Total liabilities and stockholders' equity	$ 2,834,928	$ 2,817,564

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Allowance for loan losses	$ 34,524	$ 32,915	$ 31,683	$ 31,342
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares issued	11,682,914	11,609,853
Common stock, shares,outstanding	11,682,914	11,609,853
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Interest and dividend income:
Loans and loans held for sale	$ 26,150	$ 22,371
Investment securities	2,487	1,920
Other interest-earning assets	134	73
Total interest and dividend income	28,771	24,364
Interest expense:
Deposits	2,236	1,228
Borrowed funds	292	61
Subordinated debt	228	228
Total interest expense	2,756	1,517
Net interest income	26,015	22,847
Provision for loan losses	1,600	125
Net interest income after provision for loan losses	24,415	22,722
Non-interest income:
Investment advisory fees	1,408	1,225
Deposit and interchange fees	1,489	1,340
Income on bank-owned life insurance, net	168	176
Net gains on sales of investment securities	1	540
Net gains on sales of loans	84	133
Other income	641	720
Total non-interest income	3,791	4,134
Non-interest expense:
Salaries and employee benefits	12,108	12,692
Occupancy and equipment expenses	2,157	1,939
Technology and telecommunications expenses	1,553	1,582
Advertising and public relations expenses	720	619
Audit, legal and other professional fees	507	363
Deposit insurance premiums	500	383
Supplies and postage expenses	232	233
Other operating expenses	1,670	1,609
Total non-interest expense	19,447	19,420
Income before income taxes	8,759	7,436
Provision for income taxes	1,934	1,864
Net income	$ 6,825	$ 5,572
Basic earnings per share	$ 0.59	$ 0.48
Diluted earnings per share	$ 0.58	$ 0.48
Basic weighted average common shares outstanding	11,628,587	11,508,811
Diluted weighted average common shares outstanding	11,700,854	11,598,862

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 6,825	$ 5,572
Other comprehensive (loss) income, net of taxes:
Gross unrealized holding (losses) gains on investments arising during the period	(8,069)	1,520
Income tax benefit (expense)	1,805	(544)
Net unrealized holding (losses) gains, net of tax	(6,264)	976
Less: Reclassification adjustment for net gains included in net income
Net realized gains on sales of securities during the period	1	540
Income tax expense	(1)	(193)
Reclassification adjustment for gains realized, net of tax	0	347
Total other comprehensive (loss) income, net	(6,264)	629
Comprehensive income	$ 561	$ 6,201

Consolidated Statement of Chang

Consolidated Statement of Changes in Stockholders' Equity - 3 months ended Mar. 31, 2018 - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss)/Income
Balance, beginning at Dec. 31, 2017	$ 231,810	$ 116	$ 88,205	$ 143,073	$ 416
Increase (Decrease) in Stockholders' Equity
Net income	6,825			6,825
Other comprehensive loss, net	(6,264)				(6,264)
Common stock dividend paid ($0.145 per share)	(1,686)			(1,686)
Common stock issued under dividend reinvestment plan	397	0	397
Common stock issued other	38	0	38
Stock-based compensation	591	1	590
Net settlement for employee taxes on restricted stock and options	(286)	0	(286)
Stock options exercised, net	215	0	215
Balance, ending at Mar. 31, 2018	$ 231,640	$ 117	$ 89,159	$ 148,212	$ (5,848)

Consolidated Statement of Chan7

Consolidated Statement of Changes in Stockholders' Equity (Parenthetical)	3 Months Ended
	Mar. 31, 2018$ / shares
Statement of Stockholders' Equity [Abstract]
Common stock dividend paid, per share	$ 0.145

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Cash flows from operating activities:
Net income	$ 6,825	$ 5,572
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	1,600	125
Depreciation and amortization	1,740	1,730
Stock-based compensation expense	385	324
Income on bank-owned life insurance, net	(168)	(176)
Net gains on sales of investment securities	(1)	(540)
Mortgage loans originated for sale	(3,536)	(5,554)
Proceeds from mortgage loans sold	3,828	6,504
Net gains on sales of loans	(84)	(133)
Changes in:
(Increase) decrease in other assets	(1,952)	2,114
Decrease in other liabilities	(2,410)	(1,027)
Net cash provided by operating activities	6,227	8,939
Cash flows from investing activities:
Proceeds from sales of investment securities	12,705	9,957
Net proceeds (purchases) from FHLB capital stock	2,845	(1,080)
Proceeds from maturities, calls and pay-downs of investment securities	6,347	6,062
Purchase of investment securities	(44,126)	(15,940)
Net increase in loans	(20,260)	(41,906)
Additions to premises and equipment, net	(1,371)	(2,514)
Net cash used in investing activities	(43,860)	(45,421)
Cash flows from financing activities:
Net increase in deposits	130,027	5,991
Net (decrease) increase in borrowed funds	(89,000)	36,000
Cash dividends paid	(1,686)	(1,552)
Proceeds from issuance of common stock	435	384
Net settlement for employee taxes on restricted stock and options	(286)	(694)
Proceeds from stock option exercises	215	168
Net cash provided by financing activities	39,705	40,297
Net increase in cash and cash equivalents	2,072	3,815
Cash and cash equivalents at beginning of period	54,806	50,475	$ 50,475
Cash and cash equivalents at end of period	56,878	54,290	$ 54,806
Supplemental financial data:
Cash Paid For: Interest	2,638	1,554
Cash Paid For: Income Taxes	868	760
Supplemental schedule of non-cash investing activity:
Net purchases of investment securities not yet settled	0	228
Capital expenditures incurred not yet paid	$ 0	$ 104

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies (a) Organization of Holding Company and Basis of Presentation The accompanying unaudited consolidated interim financial statements and these notes should be read in conjunction with the December 31, 2017 audited consolidated financial statements and notes thereto contained in the 2017 Annual Report on Form 10-K of Enterprise Bancorp, Inc. as filed with the Securities and Exchange Commission (the "SEC") on March 13, 2018 (the " 2017 Annual Report on Form 10-K"). The accompanying unaudited consolidated interim financial statements of Enterprise Bancorp, Inc. (the "Company," "Enterprise," "we," or "our"), a Massachusetts corporation, include the accounts of the Company and its wholly owned subsidiary, Enterprise Bank and Trust Company, commonly referred to as Enterprise Bank (the "Bank"). The Bank is a Massachusetts trust company and state chartered commercial bank organized in 1989. Substantially all of the Company's operations are conducted through the Bank and its subsidiaries. The Company has not changed its accounting policies from those disclosed in its 2017 Annual Report on Form 10-K. The Bank's subsidiaries include Enterprise Insurance Services, LLC and Enterprise Wealth Services, LLC, organized under the laws of the State of Delaware for the purposes of engaging in insurance sales activities and offering non-deposit investment products and services, respectively. In addition, the Bank has the following subsidiaries that are incorporated in the Commonwealth of Massachusetts and classified as security corporations in accordance with applicable Massachusetts General Laws: Enterprise Security Corporation; Enterprise Security Corporation II; and Enterprise Security Corporation III. The security corporations, which hold various types of qualifying securities, are limited to conducting securities investment activities that the Bank itself would be allowed to conduct under applicable laws. At March 31, 2018 , the Company had 24 full service branch banking offices serving the Greater Merrimack Valley and North Central regions of Massachusetts and Southern New Hampshire (Southern Hillsborough and Rockingham counties). Through the Bank and its subsidiaries, the Company offers a range of commercial, residential and consumer loan products, deposit products and cash management services and electronic banking options, as well as insurance services. The Company also provides a range of investment advisory, wealth management and trust services delivered via two channels, Enterprise Wealth Management and Enterprise Wealth Services. The services offered through the Bank and its subsidiaries are managed as one strategic unit and represent the Company's only reportable operating segment. The Federal Deposit Insurance Corporation (the "FDIC") and the Massachusetts Division of Banks (the "Division") have regulatory authority over the Bank. The Bank is also subject to certain regulatory requirements of the Board of Governors of the Federal Reserve System (the "Federal Reserve Board") and, with respect to its New Hampshire branch operations, the New Hampshire Banking Department. The business and operations of the Company are subject to the regulatory oversight of the Federal Reserve Board. The Division also retains supervisory jurisdiction over the Company. The accompanying unaudited consolidated interim financial statements and notes thereto have been prepared in accordance with U.S. generally accepted accounting principles ("GAAP") for interim financial information and the instructions for SEC Form 10-Q through the rules and interpretive releases of the SEC under federal securities law. In the opinion of management, the accompanying unaudited consolidated interim financial statements reflect all necessary adjustments consisting of normal recurring accruals for a fair presentation. All significant intercompany balances and transactions have been eliminated in the accompanying unaudited consolidated interim financial statements. Certain previous years' amounts in the consolidated financial statements, and notes thereto, have been reclassified to conform to the current year's presentation. Interim results are not necessarily indicative of results to be expected for the entire year, or any future period. The Company has evaluated subsequent events and transactions from March 31, 2018 through the date this Quarterly Report on Form 10-Q was filed with the SEC for potential recognition or disclosure as required by GAAP and determined that there were no material subsequent events requiring recognition or disclosure. (b) Uses of Estimates In preparing the unaudited consolidated interim financial statements in conformity with GAAP, management is required to exercise judgment in determining many of the methodologies, assumptions and estimates to be utilized. These assumptions and estimates affect the reported values of assets and liabilities as of the balance sheet date and income and expenses for the period then ended. As future events and their effects cannot be determined with precision, actual results could differ significantly from these estimates should the assumptions and estimates used change over time due to changes in circumstances. Changes in those estimates resulting from continuing change in the economic environment and other factors will be reflected in the consolidated financial statements and results of operations in future periods. As discussed in the Company's 2017 Annual Report on Form 10-K, the three most significant areas in which management applies critical assumptions and estimates are the estimates of the allowance for loan losses, impairment review of investment securities and the impairment review of goodwill. Refer to Note 1, "Summary of Significant Accounting Policies," to the Company's consolidated financial statements included in the Company's 2017 Annual Report on Form 10-K for accounting policies related to these significant estimates. The Company has not changed its significant accounting policies from those disclosed in its 2017 Annual Report on Form 10-K. (c) Restricted Instruments Certain of the Company's derivative agreements contain provisions for collateral to be posted if the derivative exposure exceeds a threshold amount. When the Company has pledged cash as collateral for this purpose, the cash is carried as restricted cash within cash and cash equivalents. See Note 7, "Derivatives and Hedging Activities" for more information about the Company's collateral related to its derivatives. The Bank is also required by the Federal Reserve Bank of Boston (the "FRB") to maintain in reserves certain amounts of vault cash and/or deposits with the FRB. The average daily reserve requirement included in “Cash and Due from Banks” was approximately $9.3 million , based on the two week computation period encompassing March 31, 2018 . As a member of the Federal Home Loan Bank of Boston (the "FHLB"), the Company is required to purchase certain levels of FHLB capital stock at par value in association with outstanding advances from the FHLB. From time-to-time, the FHLB may initiate the repurchase, at par value, of "excess" levels of its capital stock held by member banks. This stock is classified as a restricted investment and carried at cost, which management believes approximates fair value. FHLB stock represents the only restricted investment held by the Company. Management regularly reviews its holdings of FHLB stock for other-than-temporary-impairment ("OTTI"). Based on management's periodic review, the Company has not recorded any OTTI charges on this investment to date. If it was determined that a write-down of FHLB stock was required, impairment would be recognized through a charge to earnings. See Note 2, "Investment Securities," for additional information on management's OTTI review. (d) Revenue Recognition-Accounting Standard Codification (“ASC”) Topic 606 On January 1, 2018, the Company adopted ASC No. 2014-09, "Revenue from Contracts with Customers-Topic 606." The core principles require an entity to recognize revenue to depict the transfer of goods and services to customers as performance obligations are satisfied. While the majority of the Company’s revenue is generated from contracts with customers, our primary sources of revenue, interest and dividend income (primarily loan interest income), are outside of the scope of ASC 606 and accounted for under other ASC topics. We have not identified any material changes needed in our process of recording revenue or any income statement reclassifications necessary upon the adoption of the new revenue recognition standard. The primary areas of non-interest income on the Company's Consolidated Statements of Income that are within the scope of ASC 606 are discussed below. Investment advisory fees consists of income generated through Enterprise Wealth Management and Enterprise Wealth Services. Enterprise Wealth Management income is primarily generated by managing customer’s financial assets. Revenue is recognized under the accrual basis when our performance obligation is completed each month. Payment is typically received in the month following the service and the accrual is reversed. Enterprise Wealth Services revenue is generated through a third-party arrangement to refer, manage and service customers. For new sales and referrals along with transactional type charges, the performance obligation is based on a point in time and the payment is received and revenue is recognized in the same month as the revenue generating activity. For managing and servicing customers, revenue is recognized when our performance obligation is completed each month, which is generally the time the payment is received. Deposit and interchange fees are comprised of deposit account related charges and interchange income. Deposit fees consist of fees for accounts on analysis and monthly service charges, as well as transactional fees such as overdraft fees. Analysis and monthly services fees are recognized over the period the service is performed and payment is generally charged to customer’s account at the end of the month or in the following month with material amounts accrued if necessary. For transactional fees, the performance obligation and the revenue is recognized at a point of time and payment is typically received as the service is rendered. Interchange income is generated primarily from retail debit card transactions processed through the card payment network. The performance obligation and the revenue are recognized when the service is performed and payment is received as services are rendered. The following non-interest income components are not subject to ASC 606: Income on bank-owned life insurance, Net gains on sales of investment securities, and Net gains on sales of loans, and are covered under other ASC topics. The remaining revenue items in Non-interest income are not material. For further information on the Company's adoption of Accounting Standards Update ("ASU") 2014-09, "Revenue from Contracts with Customers (Topic 606), see Item (f) "Recent Accounting Pronouncements" under the subheading "Accounting pronouncements adopted by the Company" below in this Note 1. See also the Company's most recent 2017 Annual Report on Form 10-K Note 1, "Summary of Significant Accounting Policies," to the Company's consolidated financial statements for additional accounting policies on revenue recognition related to loans, investments, gains and losses on debt security sales, and net gains on loans held for sale. (e) Income Taxes The Company and its subsidiaries file income tax returns in the U.S. federal jurisdiction and in the states of Massachusetts and New Hampshire within the directives of the respective enacted tax legislation. The Company uses the asset and liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are recognized for the future tax expense or benefit attributable to differences between the financial statement carrying amounts and the tax basis of assets and liabilities. The deferred tax assets and liabilities are reflected at currently enacted income tax rates applicable to the period in which the deferred tax assets or liabilities are expected to be realized or settled. As changes in tax laws or rates are enacted, deferred tax assets and liabilities will be adjusted accordingly through the provision for income taxes in the period that includes the enactment date. The Company's policy is to classify interest resulting from underpayment of income taxes as income tax expense in the first period the interest would begin accruing according to the provisions of the relevant tax law. The Company classifies penalties resulting from underpayment of income taxes as income tax expense in the period for which the Company claims or expects to claim an uncertain tax position or in the period in which the Company's judgment changes regarding an uncertain tax position. The income tax provisions will differ from the expense that would result from applying the federal statutory rate to income before taxes, due primarily to the impact of tax-exempt interest from certain investment securities, loans and bank-owned life insurance ("BOLI"). The Company did not have any unrecognized tax benefits accrued as income tax liabilities or receivables or as deferred tax items at March 31, 2018 . The Company is subject to U.S. federal and state income tax examinations by taxing authorities for the 2014 through 2017 tax years. (f) Recent Accounting Pronouncements Accounting pronouncements adopted by the Company In May 2014, the Financial Accounting Standards Board ("FASB ") issued Accounting Standards Update ("ASU") No. 2014-09, "Revenue from Contracts with Customers (Topic 606)." This ASU is intended to create a single source of revenue guidance which is more principles based than current revenue guidance. The guidance affects any entity that either enters into contracts with customers to transfer goods or services, or enters into contracts for the transfer of non-financial assets, unless those contracts are within the scope of other standards. In the first quarter of 2018, the Company adopted ASU 2014-09. Because the largest portion of the Company's revenue, interest income and various loan fees, is specifically excluded from the scope of this ASU, and because the Company recognizes the majority of the remaining revenue sources in a manner that is consistent with this ASU, the adoption of this standard did not materially impact the Company's consolidated financial statements, results of operations or disclosures. For further information regarding the Company's revenue policies see Item (d) "Revenue Recognition-Accounting Standard Codification (“ASC”) Topic 606" above in this Note 1. 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," which updates certain aspects of recognition, measurement, presentation and disclosure of financial instruments. Among other things, ASU No. 2016-01: • Requires equity investments (except 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; • Requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; and • 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. The FASB has since issued an additional related ASU amendment intended to clarify certain aspects and improve understanding of the implementation guidance in ASU No. 2016-01 but does not change the core principles of the original guidance. This ASU is effective for public companies for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Because the Company's investment in equity securities at March 31, 2018 was immaterial, the adoption of this ASU by the Company in the first quarter of 2018 did not have a material impact on the Company's consolidated financial statements, results of operations or disclosures. The fair value changes of equity securities that will be recognized in net income in the future will depend on the amount of dollars invested and the magnitude of changes in equity market values. For further information regarding the Company's recognition and measurement of financial assets and liabilities see Note 2, "Investment Securities," and Note 12, "Fair Value Measures" in this Form 10-Q. In August 2016, the FASB issued ASU No. 2016-15, "Statement of Cash flows (Topic 230) - Classification of Certain Cash Receipts and Cash Payments." The amendments are intended to reduce diversity in practice related to the presentation of eight specific cash flow issues. For public business entities that are SEC filers, such as the Company, the amendments in this Update are effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Because this amendment primarily impacts the presentation and classification of information, this ASU did not materially impact the Company's consolidated financial statements and results of operations upon adoption in the first quarter of 2018. In November 2016, the FASB issued ASU No. 2016-18, "Statement of Cash flows-Restricted Cash (Topic 230)." The amendments in this Update clarify the inclusion of restricted cash in the cash and cash equivalents beginning-of-period and end-of period reconciliation on the statement of cash flows. For public business entities that are SEC filers, such as the Company, the amendments in this Update are effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Because this amendment primarily impacts the presentation and classification of information, this ASU did not have a significant impact on the Company's consolidated financial statements and results of operations upon adoption in the first quarter of 2018. For further information regarding the Company's restricted cash see Item (c) "Restricted Instruments" above in this Note 1. In March 2017, the FASB issued ASU No. 2017-07, "Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost." The amendments in this Update outline the presentation, classification and disclosure requirements for service cost and other components of net benefit costs. For public business entities that are SEC filers, such as the Company, the amendments in this Update are effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Because this amendment primarily impacts the presentation and classification of information, the adoption of this ASU in the first quarter of 2018 did not have a material impact on the Company's consolidated financial statements and results of operations. For further information regarding the Company's compensation retirement benefits see Note 9, "Supplemental Retirement Plans and Other Post-retirement Benefit Obligations" In May 2017, the FASB issued ASU No. 2017-09, "Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting." The amendments in this Update apply to entities that change the terms of an outstanding share-based payment award. The amendments are intended to reduce diversity in practice as well as cost and complexity when applying guidance in Topic 718 to the modification of the terms and conditions of a share-based payment award. This ASU provides guidance on the three modifications to share-based payment awards and conditions that must be met in order to exempt an entity from modification accounting under topic 718. The amendments in this Update apply prospectively to award modifications on or after the adoption date, and are effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The adoption of this ASU in the first quarter of 2018 did not have an impact on the Company's consolidated financial statements, results of operations or disclosures because to date the Company has not made any such modifications. For further information regarding the Company's stock compensation see Note 10, "Stock-Based Compensation" Accounting pronouncements not yet adopted by the Company (in order of effective date of implementation) In February 2016, the FASB issued ASU No. 2016-02, "Leases (Topic 842)," which supersedes previous leasing guidance in Topic 840, Leases. Under the new guidance, lessees are required to recognize lease assets and lease liabilities on the balance sheet for all leases with terms longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. The new standard is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. A modified retrospective transition approach is required for lessees for capital and operating leases existing at, or entered into after, the beginning of the earliest comparative period presented in the consolidated financial statements, with certain practical expedients available. The Company is currently evaluating the effects of this ASU on the Company's consolidated financial statements, results of operations and disclosures. Based on the Company's evaluation to date, management believes the more significant implication of this ASU on the Company relates to operating leases of our facilities, mainly branch leases. As of March 31, 2018 , the Company had leases on 17 of its locations, including branches and part of its main campus, and expects that upon adoption of this ASU the balance sheet will reflect both lease liabilities, equal to the present value of lease payments, and right-of-use assets, equal to the lease liability plus payments made to lessors adjusted for prepaid or accrued rent and any initial direct cost incurred. In addition, the Company will recognize lease expense in the income statement on a straight-line basis similar to current operating leases. The straight-line expense will reflect the interest expense on the lease liability (effective interest method) and amortization of the right-of-use asset. Lease expense will be presented as a single line item in the operating expense section of the income statement. Management believes that lease expense under the new standard will generally approximate lease expense under current GAAP. The foregoing observations are subject to change as management completes their evaluation. In June 2016, the FASB issued ASU No. 2016-13, "Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments." The amendments in this ASU require a financial asset (or a group of financial assets) measured at amortized cost basis to be presented at the net amount expected to be collected. Previously, when credit losses were measured under GAAP, an entity generally only considered past events and current conditions in measuring the incurred loss and generally recognition of the full amount of credit losses was delayed until the loss was probable of occurring. The amendments in this ASU eliminate the probable initial recognition threshold in current GAAP and, instead, reflect an entity’s current estimate of all expected credit losses (commonly known as "CECL"). The measurement of expected credit losses is based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. An entity must use judgment in determining the relevant information and estimation methods that are appropriate in its circumstances. The income statement reflects the measurement of credit losses for newly recognized financial assets, as well as the expected increases or decreases of expected credit losses that have taken place during the period. The allowance for credit losses is a valuation account that is deducted from the amortized cost basis of the financial asset(s) to present the net fair value at the amount expected to be collected on the financial asset. Credit losses on available-for-sale debt securities should be measured in a manner similar to current GAAP. However, the amendments in this Update require that credit losses be presented as an allowance rather than as a write-down. Unlike current GAAP, the ASU provides for reversals of credit losses in future period net income in situations where the estimate of loss declines. An entity will apply the amendments in this Update through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective (that is, a modified-retrospective approach). For public business entities that are SEC filers, such as the Company, the amendments in this Update are effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption for fiscal years beginning after December 15, 2018 is permitted. In April, 2018, banking regulators issued a proposed revision to their capital rules that addresses the regulatory capital treatment of credit loss allowances under the CECL methodology and, if enacted as proposed, would allow banking organizations to phase in the day-one regulatory capital effects of CECL adoption over three years. The Company has established an implementation committee and an enterprise-wide implementation plan for this ASU, which will consider the impact to operations, financial results, capital, and disclosures and controls. At present, the impact of the adoption of ASU No. 2016-13 on the Company's operations, financial results, disclosures, and controls is unknown. In January 2017, the FASB issued ASU No. 2017-04, "Intangibles-Goodwill and Other (Topic 350)-Simplifying the Test for Goodwill Impairment." The main provision in this ASU eliminated Step 2 of the goodwill impairment test and instead requires an entity to perform its annual, or interim, goodwill impairment test by comparing the fair value of the reporting unit with its carrying amount. An impairment charge would be recognized for the amount the carrying value exceeds the reporting unit's fair value as long as the amount recognized doesn't exceed the amount of goodwill allocated to the reporting unit. For public business entities that are SEC filers, such as the Company, the amendments in this Update are effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted for impairment tests performed on testing dates after January 1, 2017. Goodwill carried on the Company’s consolidated financial statements was $5.7 million at both March 31, 2018 and December 31, 2017 . This asset is related to the Company’s acquisition of two branch offices in July 2000. The Company does not expect the adoption of ASU No. 2017-01 to have a material impact on the Company's consolidated financial statements and results of operations.

Investment Securities

Investment Securities	3 Months Ended
	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Investment Securities	Investment Securities As of March 31, 2018 , the investment portfolio was primarily comprised of debt securities, with a small portion of the portfolio invested in equity securities. The Company had only debt securities at December 31, 2017 , as the equity portfolio was liquidated during 2017 in order to reduce the potential impact from market changes on earnings due to new accounting rules in effect on January 1, 2018. See Note 12, "Fair Value Measurements," below for further information regarding the Company's fair value measurements for available-for-sale securities and refer to Note 1, Item (c) "Restricted Instruments" for information regarding the Company's investment in FHLB stock. Debt Securities The amortized cost and fair values of debt securities at the dates specified are summarized as follows: March 31, 2018 (Dollars in thousands) Amortized cost Unrealized gains Unrealized losses Fair Value Federal agency obligations (1) $ 51,802 $ — $ 417 $ 51,385 Residential federal agency MBS (1) 154,739 5 3,627 151,117 Commercial federal agency MBS (1) 66,653 — 1,799 64,854 Municipal securities 134,306 495 1,942 132,859 Corporate bonds 11,326 6 276 11,056 Certificates of deposits (2) 950 — 8 942 Total debt securities, at fair value $ 419,776 $ 506 $ 8,069 $ 412,213 December 31, 2017 (Dollars in thousands) Amortized cost Unrealized gains Unrealized losses Fair Value Federal agency obligations (1) $ 51,769 $ 30 $ 82 $ 51,717 Residential federal agency MBS (1) 141,054 71 971 140,154 Commercial federal agency MBS (1) 66,777 9 286 66,500 Municipal securities 132,603 2,097 354 134,346 Corporate bonds 11,546 63 67 11,542 Certificates of deposits (2) 950 — 3 947 Total debt securities, at fair value $ 404,699 $ 2,270 $ 1,763 $ 405,206 __________________________________________ (1) These categories may include investments issued or guaranteed by government sponsored enterprises such as Fannie Mae ("FNMA"), Freddie Mac ("FHLMC"), Federal Farm Credit Bank ("FFCB"), or one of several Federal Home Loan Banks, as well as, investments guaranteed by Ginnie Mae ("GNMA"), a wholly-owned government entity. (2) Certificates of deposit ("CDs") represent term deposits issued by banks that are subject to FDIC insurance and purchased on the open market. Included in the residential and commercial federal agency MBS categories were collateralized mortgage obligations ("CMOs") issued by U.S. agencies with fair values totaling $183.2 million and $171.7 million at March 31, 2018 and December 31, 2017 , respectively. As of the dates reflected in the tables above, all of the Company’s debt securities were classified as available-for-sale and carried at fair value. Net unrealized appreciation and depreciation on debt securities available-for-sale, net of applicable income taxes, are reflected as a component of accumulated other comprehensive income (loss). The net unrealized gain or loss in the Company's debt security portfolio fluctuates as market interest rates rise and fall. Due to the predominantly fixed rate nature of this portfolio, as market rates fall, the value of the portfolio rises, and as market rates rise, the value of the portfolio declines. The unrealized gains or losses on debt securities will also decline as the securities approach maturity. Unrealized losses on debt securities that are deemed OTTI are generally charged to earnings, as described further in Note 1, "Summary of Significant Accounting Policies" under Item (d) "Investments" to the Company's consolidated financial statements in the Company's recent 2017 Annual Report on Form 10-K. Gains or losses will be recognized in the income statement if the securities are sold. The following tables summarize debt securities having temporary impairment, due to the fair market values having declined below the amortized costs of the individual investments, and the period that the investments have been temporarily impaired at March 31, 2018 and December 31, 2017 . March 31, 2018 Less than 12 months 12 months or longer Total (Dollars in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses # of holdings Federal agency obligations $ 51,385 $ 417 $ — $ — $ 51,385 $ 417 15 Residential federal agency MBS 145,472 3,480 1,983 147 147,455 3,627 41 Commercial federal agency MBS 59,804 1,586 5,050 213 64,854 1,799 16 Municipal securities 84,911 1,382 9,834 560 94,745 1,942 151 Corporate bonds 7,490 170 2,541 106 10,031 276 59 Certificates of deposit 942 8 — — 942 8 4 Total temporarily impaired debt securities $ 350,004 $ 7,043 $ 19,408 $ 1,026 $ 369,412 $ 8,069 286 December 31, 2017 Less than 12 months 12 months or longer Total (Dollars in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses # of holdings Federal agency obligations $ 34,344 $ 82 $ — $ — $ 34,344 $ 82 9 Residential federal agency MBS 109,308 882 2,015 89 111,323 971 30 Commercial federal agency MBS 35,859 205 5,190 81 41,049 286 11 Municipal securities 16,983 129 10,210 225 27,193 354 50 Corporate bonds 2,802 23 2,913 44 5,715 67 33 Certificates of deposit 947 3 — — 947 3 4 Total temporarily impaired debt securities $ 200,243 $ 1,324 $ 20,328 $ 439 $ 220,571 $ 1,763 137 During the three months ended March 31, 2018 and 2017 , the Company did not record any fair value impairment charges (OTTI) on its investments in debt securities. At March 31, 2018 , management did not consider any debt securities to have OTTI and attributes the unrealized losses to increases in current market yields compared to the yields at the time the investments were purchased by the Company. Management regularly reviews the portfolio for debt securities with unrealized losses that are other-than-temporarily impaired. There have been no material changes to the Company's process for assessing investments for OTTI as reported in the 2017 Annual Report on Form 10-K. For more information about the Company's assessment for OTTI see Note 2, "Investment Securities" to the Company's consolidated financial statements in the Company's recent 2017 Annual Report on Form 10-K. The contractual maturity distribution at March 31, 2018 of total debt securities was as follows: (Dollars in thousands) Amortized Cost Fair Value Due in one year or less $ 19,471 $ 19,491 Due after one, but within five years 81,704 80,955 Due after five, but within ten years 134,234 131,440 Due after ten years 184,367 180,327 Total debt securities $ 419,776 $ 412,213 Scheduled contractual maturities shown above may not reflect the actual maturities of the investments. The actual MBS/CMO cash flows likely will be faster than presented above due to prepayments and amortization. Similarly, included in the fair value of debt securities above are callable securities, comprised of municipal securities and corporate bonds totaling $76.5 million , which can be redeemed by the issuers prior to the maturity presented above. Management considers these factors when evaluating the interest rate risk in the Company's asset-liability management program. From time to time, the Company may pledge debt securities as collateral for deposit account balances of municipal customers, and for borrowing capacity with the FHLB and the FRB. The fair value of debt securities pledged as collateral for these purposes was $ 411.3 million at March 31, 2018 . Sales of investments in debt securities, including pending trades based on trade date, if applicable, for the three months ended March 31, 2018 and March 31, 2017 are summarized as follows: Three months ended March 31, (Dollars in thousands) 2018 2017 Amortized cost of debt securities sold (1) $ 668 $ 2,262 Gross realized gains on sales 3 32 Gross realized losses on sales (2 ) — Total proceeds from sales of debt securities $ 669 $ 2,294 _________________________________________ (1) Amortized cost of investments sold is determined on a specific identification basis. Equity Securities As of March 31, 2018 , the Company held equity securities with a fair value of $295 thousand , compared to no equity securities at December 31, 2017 . At March 31, 2018 , the equity portfolio consisted primarily of investments in a diversified group of mutual funds. The Company adopted ASU 2016-01 in the first quarter of 2018. As a result, the fair market value fluctuations associated with the equity portfolio are recognized in the Company’s Consolidated Statement of Income in the "Other income" line item. During the first quarter of the 2018, the Company’s holding in equity investments and the related fair value gain/loss on equity securities was immaterial. No sales on equity securities were recorded in the first quarter of 2018. For the three months ended March 31, 2017 , the amortized cost of equity securities sold including pending trades based on trade date, if applicable, amounted to $6.9 million , resulting in net realized gains of $508 thousand . The amortized cost of equity securities sold is determined on a specific identification basis.

Loans

Loans	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Loans	Loans The Company specializes in lending to business entities, non-profit organizations, professional practices and individuals. The Company's primary lending focus is on the development of high quality commercial relationships achieved through active business development efforts, long-term relationships with established commercial developers, strong community involvement and focused marketing strategies. Loans made to businesses include commercial mortgage loans, construction and land development loans, secured and unsecured commercial loans and lines of credit, and letters of credit. The Company also originates equipment lease financing for businesses. Loans made to individuals include conventional residential mortgage loans, home equity loans and lines, residential construction loans on owner-occupied primary and secondary residences, and secured and unsecured personal loans and lines of credit. The Company manages its loan portfolio to avoid concentration by industry, relationship size and source of repayment to lessen its credit risk exposure. See Note 4, "Allowance for Loan Losses," for information on the Company's credit risk management, non-accrual, impaired and troubled debt restructured loans and the allowance for loan losses. Major classifications of loans at the periods indicated were as follows: (Dollars in thousands) March 31, December 31, Commercial real estate $ 1,254,705 $ 1,201,351 Commercial and industrial 503,657 498,802 Commercial construction 228,797 274,905 Total commercial loans 1,987,159 1,975,058 Residential mortgages 198,756 195,492 Home equity loans and lines 96,531 91,706 Consumer 10,149 10,293 Total retail loans 305,436 297,491 Gross loans 2,292,595 2,272,549 Deferred loan origination fees, net (2,422 ) (2,645 ) Total loans 2,290,173 2,269,904 Allowance for loan losses (34,524 ) (32,915 ) Net loans $ 2,255,649 $ 2,236,989 Loan Portfolio Classifications - Commercial loans: Commercial real estate loans include loans secured by both owner-use and non-owner occupied real estate. These loans are typically secured by a variety of commercial and industrial property types, including one-to-four and multi-family apartment buildings, office, industrial or mixed-use facilities, strip shopping centers, or other commercial properties, and are generally guaranteed by the principals of the borrower. Commercial real estate loans generally have repayment periods of approximately fifteen to twenty-five years. Variable interest rate loans have a variety of adjustment terms and underlying interest rate indices, and are generally fixed for an initial period before periodic rate adjustments begin. Commercial and industrial loans include seasonal revolving lines of credit, working capital loans, equipment financing (including equipment leases), and term loans. Also included in commercial and industrial loans are loans partially guaranteed by the U.S. Small Business Administration ("SBA"), and loans under various programs and agencies. Commercial and industrial credits may be unsecured loans and lines to financially strong borrowers, loans secured in whole or in part by real estate unrelated to the principal purpose of the loan or secured by inventories, equipment, or receivables, and are generally guaranteed by the principals of the borrower. Variable rate loans and lines in this portfolio have interest rates that are periodically adjusted, with loans generally having fixed initial periods. Commercial and industrial loans have average repayment periods of one to seven years. Commercial construction loans include the development of residential housing and condominium projects, the development of commercial and industrial use property, and loans for the purchase and improvement of raw land. These loans are secured in whole or in part by the underlying real estate collateral and are generally guaranteed by the principals of the borrowers. Construction lenders work to cultivate long-term relationships with established developers. The Company limits the amount of financing provided to any single developer for the construction of properties built on a speculative basis. Funds for construction projects are disbursed as pre-specified stages of construction are completed. Regular site inspections are performed, prior to advancing additional funds, at each construction phase, either by experienced construction lenders on staff at the Bank or by independent outside inspection companies. Commercial construction loans generally are variable rate loans and lines of credit with interest rates that are periodically adjusted and generally have terms of one to three years. From time to time, the Company participates with other banks in the financing of certain commercial projects. Participating loans with other institutions provide banks the opportunity to retain customer relationships and reduce credit risk exposure among each participating bank, while providing customers with larger credit vehicles than the individual bank might be willing or able to offer independently. In some cases, the Company may act as the lead lender, originating and servicing the loans, but participating out a portion of the funding to other banks. In other cases, the Company may participate in loans originated by other institutions. In each case, the participating bank funds a percentage of the loan commitment and takes on the related pro-rata risk. In each case in which the Company participates in a loan, the rights and obligations of each participating bank are divided proportionately among the participating banks in an amount equal to their share of ownership and with equal priority among all banks. When the participation qualifies as a sale under GAAP, the balances participated out to other institutions are not carried as assets on the Company's financial statements. The Company performs an independent credit analysis of each commitment and a review of the participating institution prior to participation in the loan, and an annual review thereafter of each participating institution. Loans originated by other banks in which the Company is a participating institution are carried in the loan portfolio at the Company's pro rata share of ownership. Loans originated by other banks in which the Company is a participating institution amounted to $90.6 million at March 31, 2018 and $91.6 million at December 31, 2017 . See also "Loans serviced for others" below for information related to commercial loans participated out to various other institutions. Letters of credit are conditional commitments issued by the Company to guarantee the financial obligation or performance of a customer to a third party. The credit risk involved in issuing letters of credit is essentially the same as that involved in extending loan facilities to customers. If the letter of credit is drawn upon, a loan is created for the customer, generally a commercial loan, with the same criteria associated with similar commercial loans. - Residential mortgage loans: Enterprise originates conventional mortgage loans on one-to-four family residential properties. These properties may serve as the borrower's primary residence, or as vacation homes or investment properties. Loan-to-value limits vary, generally from 75% for multi-family, owner-occupied properties, up to 97% for single family, owner-occupied properties, with mortgage insurance coverage required for loan-to-value ratios greater than 80% based on program parameters. In addition, financing is provided for the construction of owner-occupied primary and secondary residences. Residential mortgage loans may have terms of up to 30 years at either fixed or adjustable rates of interest. Fixed and adjustable rate residential mortgage loans are generally originated using secondary market underwriting and documentation standards. Depending on the current interest rate environment, management projections of future interest rates and the overall asset-liability management program of the Company, management may elect to sell those fixed and adjustable rate residential mortgage loans which are eligible for sale in the secondary market, or hold some or all of this residential loan production for the Company's portfolio. Mortgage loans are generally not pooled for sale, but instead sold on an individual basis. The Company may retain or sell the servicing when selling the loans. Loans sold are subject to standard secondary market underwriting and eligibility representations and warranties over the life of the loan and are subject to an early payment default period covering the first four payments for certain loan sales. Loans classified as held for sale are carried as a separate line item on the balance sheet. - Home equity loans and lines of credit: Home equity term loans are originated for one-to-four family residential properties with maximum original loan-to-value ratios generally up to 80% of the automated valuation or appraised value of the property securing the loan. Home equity loan payments consist of monthly principal and interest based on amortization ranging from three to fifteen years. The rates may be variable or fixed. The Company originates home equity revolving lines of credit for one-to-four family residential properties with maximum original loan-to-value ratios generally up to 80% of the automated valuation or appraised value of the property securing the loan. Home equity lines generally have interest rates that adjust monthly based on changes in the Wall Street Journal Prime Rate, although minimum rates may be applicable. Some home equity line rates may be fixed for a period of time and then adjusted monthly thereafter. The payment schedule for home equity lines requires interest only payments for the first ten years of the lines. Generally at the end of ten years, the line may be frozen to future advances, and principal plus interest payments are collected over a fifteen -year amortization schedule or, for eligible borrowers meeting certain requirements, the line availability may be extended for an additional interest only period. - Consumer loans: Consumer loans consist primarily of secured or unsecured personal loans, unsecured loans under energy efficiency financing programs in conjunction with Massachusetts public utilities, and unsecured overdraft protection lines on checking accounts extended to individual customers. The aggregate amount of overdrawn deposit accounts are reclassified as loan balances. Loans serviced for others At March 31, 2018 and December 31, 2017 , the Company was servicing residential mortgage loans owned by investors amounting to $18.0 million and $18.4 million , respectively. Additionally, the Company was servicing commercial loans originated by the Company and participated out to various other institutions amounting to $70.8 million and $70.7 million at March 31, 2018 and December 31, 2017 , respectively. See the discussion above under the heading "Commercial loans" for further information regarding commercial participations. Loans serving as collateral Loans designated as qualified collateral and pledged to the FHLB for borrowing capacity for the periods indicated are summarized below: (Dollars in thousands) March 31, December 31, Commercial real estate $ 216,078 $ 224,703 Residential mortgages 188,758 187,524 Home equity 8,802 9,405 Total loans pledged to FHLB $ 413,638 $ 421,632 See Note 12, "Fair Value Measurements," below for further information regarding the Company's fair value measurements for loans, and Note 7, "Derivatives and Hedging Activities," below for information regarding interest-rate swap agreements related to certain commercial loans.

Allowance For Loan Loss

Allowance For Loan Loss	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Allowance for Loan Loss	Allowance for Loan Losses Allowance for probable loan losses methodology On a quarterly basis, management prepares an estimate of the allowance necessary to cover estimated probable credit losses. The Company uses a systematic methodology to measure the amount of estimated loan loss exposure inherent in the portfolio for purposes of establishing a sufficient allowance for loan losses. The methodology makes use of specific reserves for loans individually evaluated and deemed impaired, and general reserves for larger groups of homogeneous loans, which are collectively evaluated relying on a combination of qualitative and quantitative factors that may affect credit quality of the pool. There have been no material changes to the Company's underwriting practices, credit risk management system, or to the allowance assessment methodology used to estimate loan loss exposure as reported in the 2017 Annual Report on Form 10-K. Refer to Note 4, "Allowance for Loan Losses," to the Company's consolidated financial statements contained in the 2017 Annual Report on Form 10-K for further discussion of management's methodology used to estimate a sufficient allowance for loan losses, the credit risk management function and adversely classified loan rating system. The balances of loans as of March 31, 2018 by portfolio classification and evaluation method are summarized as follows: (Dollars in thousands) Loans individually evaluated for impairment Loans collectively evaluated for impairment Gross Loans Commercial real estate $ 13,686 $ 1,241,019 $ 1,254,705 Commercial and industrial 11,148 492,509 503,657 Commercial construction 1,670 227,127 228,797 Residential mortgages 715 198,041 198,756 Home equity loans and lines 505 96,026 96,531 Consumer 23 10,126 10,149 Total gross loans $ 27,747 $ 2,264,848 $ 2,292,595 The balances of loans as of December 31, 2017 by portfolio classification and evaluation method are summarized as follows: (Dollars in thousands) Loans individually evaluated for impairment Loans collectively evaluated for impairment Gross Loans Commercial real estate $ 13,739 $ 1,187,612 $ 1,201,351 Commercial and industrial 10,096 488,706 498,802 Commercial construction 1,624 273,281 274,905 Residential mortgages 397 195,095 195,492 Home equity loans and lines 371 91,335 91,706 Consumer 35 10,258 10,293 Total gross loans $ 26,262 $ 2,246,287 $ 2,272,549 See "Financial Condition," in Item 2, "Management's Discussion and Analysis," under the headings "Credit Risk" and "Allowance for Loan Losses" in this Form 10-Q for additional information about changes in the Company's Credit quality indicators since December 31, 2017 . Credit quality indicators Early detection of credit issues is critical to minimize credit losses. Accordingly, management regularly monitors internal credit quality indicators such as, among others, the risk classification of adversely classified loans, past due and non-accrual loans, impaired and restructured loans, and the level of foreclosure activity. These credit quality indicators are discussed below. Adversely classified loans The Company's loan risk rating system classifies loans depending on risk of loss characteristics. The classifications range from "substantially risk free" for the highest quality loans and loans that are secured by cash collateral, through a satisfactory range of "minimal," "moderate," "better than average," and "average" risk, to the regulatory problem-asset classifications of "criticized," for loans that may need additional monitoring, and the more severe adverse classifications of "substandard," "doubtful," and "loss" based on criteria established under banking regulations. Loans which are evaluated to be of weaker credit quality are placed on the "watch credit list" and reviewed on a more frequent basis by management. Adversely classified loans may be accruing or in non-accrual status and may be additionally designated as impaired or restructured, or some combination thereof. The following tables present the Company's credit risk profile for each portfolio classification by internally assigned adverse risk rating category as of the periods indicated. March 31, 2018 Adversely Classified Not Adversely (Dollars in thousands) Substandard Doubtful Loss Classified Gross Loans Commercial real estate $ 13,117 $ — $ — $ 1,241,588 $ 1,254,705 Commercial and industrial 10,137 46 1 493,473 503,657 Commercial construction 1,670 — — 227,127 228,797 Residential mortgages 1,663 — — 197,093 198,756 Home equity loans and lines 555 — — 95,976 96,531 Consumer 40 9 — 10,100 10,149 Total gross loans $ 27,182 $ 55 $ 1 $ 2,265,357 $ 2,292,595 December 31, 2017 Adversely Classified Not Adversely (Dollars in thousands) Substandard Doubtful Loss Classified Gross Loans Commercial real estate $ 12,895 $ — $ — $ 1,188,456 $ 1,201,351 Commercial and industrial 9,915 48 1 488,838 498,802 Commercial construction 1,624 — — 273,281 274,905 Residential mortgages 1,355 — — 194,137 195,492 Home equity loans and lines 513 — — 91,193 91,706 Consumer 52 10 — 10,231 10,293 Total gross loans $ 26,354 $ 58 $ 1 $ 2,246,136 $ 2,272,549 Total adversely classified loans amounted to 1.19% of total loans at March 31, 2018 , as compared to 1.16% at December 31, 2017 . Past due and non-accrual loans The following tables present an age analysis of past due loans by portfolio classification as of the dates indicated: Balance at March 31, 2018 (Dollars in thousands) 30-59 Days Past Due 60-89 Days Past Due Past Due 90 days or more Total Past Due Loans Current Loans Gross Loans Non-accrual Loans Commercial real estate $ 6,405 $ 1,428 $ 3,574 $ 11,407 $ 1,243,298 $ 1,254,705 $ 6,485 Commercial and industrial 969 894 1,458 3,321 500,336 503,657 2,771 Commercial construction 234 — — 234 228,563 228,797 192 Residential mortgages 1,209 92 88 1,389 197,367 198,756 582 Home equity loans and lines 189 126 131 446 96,085 96,531 505 Consumer 49 10 — 59 10,090 10,149 23 Total gross loans $ 9,055 $ 2,550 $ 5,251 $ 16,856 $ 2,275,739 $ 2,292,595 $ 10,558 Balance at December 31, 2017 (Dollars in thousands) 30-59 Days Past Due 60-89 Days Past Due Past Due 90 days or more Total Past Due Loans Current Loans Gross Loans Non-accrual Loans Commercial real estate $ 4,200 $ 69 $ 3,569 $ 7,838 $ 1,193,513 $ 1,201,351 $ 6,751 Commercial and industrial 374 527 327 1,228 497,574 498,802 1,294 Commercial construction 2,526 518 — 3,044 271,861 274,905 193 Residential mortgages 1,931 93 89 2,113 193,379 195,492 262 Home equity loans and lines 491 120 12 623 91,083 91,706 463 Consumer 51 5 45 101 10,192 10,293 69 Total gross loans $ 9,573 $ 1,332 $ 4,042 $ 14,947 $ 2,257,602 $ 2,272,549 $ 9,032 At March 31, 2018 and December 31, 2017 , all loans past due 90 days or more were carried as non-accrual, in addition to those loans less than 90 days past due where reasonable doubt existed as to the full and timely collection of interest or principal that have also been designated as non-accrual, despite their payment due status shown in the tables above. Non-accrual loans that were not adversely classified amounted to $224 thousand at March 31, 2018 and $21 thousand at December 31, 2017 . These balances primarily represented the guaranteed portions of non-performing SBA loans. The majority of the non-accrual loan balances were also carried as impaired loans during the periods noted, and are discussed further below. The ratio of non-accrual loans to total loans amounted to 0.46% at March 31, 2018 , and 0.40% at December 31, 2017 . At March 31, 2018 , additional funding commitments for non-accrual loans was not material. Impaired loans Impaired loans are individually significant loans for which management considers it probable that not all amounts due (principal and interest) will be collected in accordance with the original contractual terms. Impaired loans include loans that have been modified in a troubled debt restructuring ("TDR"), see "Troubled debt restructurings" below. Impaired loans are individually evaluated for credit loss and a specific allowance reserve is assigned for the amount of the estimated probable credit loss. The carrying value of impaired loans amounted to $27.7 million and $26.3 million at March 31, 2018 and December 31, 2017 , respectively. Total accruing impaired loans amounted to $17.2 million and $17.4 million at March 31, 2018 and December 31, 2017 , respectively, while non-accrual impaired loans amounted to $10.6 million and $8.9 million as of March 31, 2018 and December 31, 2017 , respectively. The following tables set forth the recorded investment in impaired loans and the related specific allowance allocated by portfolio classification as of the dates indicated: Balance at March 31, 2018 (Dollars in thousands) Unpaid contractual principal balance Total recorded investment in impaired loans Recorded investment with no allowance Recorded investment with allowance Related specific allowance Commercial real estate $ 14,994 $ 13,686 $ 13,159 $ 527 $ 52 Commercial and industrial 11,550 11,148 6,530 4,618 2,776 Commercial construction 1,726 1,670 1,670 — — Residential mortgages 835 715 581 134 4 Home equity loans and lines 714 505 505 — — Consumer 23 23 — 23 22 Total $ 29,842 $ 27,747 $ 22,445 $ 5,302 $ 2,854 Balance at December 31, 2017 (Dollars in thousands) Unpaid contractual principal balance Total recorded investment in impaired loans Recorded investment with no allowance Recorded investment with allowance Related specific allowance Commercial real estate $ 15,132 $ 13,739 $ 12,850 $ 889 $ 59 Commercial and industrial 10,458 10,096 7,053 3,043 1,284 Commercial construction 1,678 1,624 1,624 — — Residential mortgages 511 397 262 135 5 Home equity loans and lines 543 371 371 — — Consumer 36 35 — 35 35 Total $ 28,358 $ 26,262 $ 22,160 $ 4,102 $ 1,383 The following table presents the average recorded investment in impaired loans by portfolio classification and the related interest recognized during the periods indicated: Three Months Ended March 31, 2018 Three Months Ended March 31, 2017 (Dollars in thousands) Average recorded investment Interest income (loss) recognized Average recorded investment Interest income (loss) recognized Commercial real estate $ 13,715 $ 94 $ 13,378 $ 101 Commercial and industrial 10,647 77 12,878 105 Commercial construction 1,636 22 2,412 27 Residential mortgages 614 (1 ) 287 — Home equity loans and lines 475 — 539 (2 ) Consumer 32 — 13 — Total $ 27,119 $ 192 $ 29,507 $ 231 At March 31, 2018 , additional funding commitments for impaired loans was not material. The Company's obligation to fulfill the additional funding commitments on impaired loans is generally contingent on the borrower's compliance with the terms of the credit agreement. If the borrower is not in compliance, additional funding commitments may or may not be made at the Company's discretion. Troubled debt restructurings Loans are designated as a TDR when, as part of an agreement to modify the original contractual terms of the loan as a result of financial difficulties of the borrower, the Bank grants the borrower a concession on the terms that would not otherwise be considered. Typically, such concessions may consist of one or a combination of the following: a reduction in interest rate to a below market rate, taking into account the credit quality of the note; extension of additional credit based on receipt of adequate collateral; or a deferment or reduction of payments (principal or interest) which materially alters the Bank's position or significantly extends the note's maturity date, such that the present value of cash flows to be received is materially less than those contractually established at the loan's origination. All loans that are modified are reviewed by the Company to identify if a TDR has occurred. TDR loans are included in the impaired loan category and, as such, these loans are individually reviewed and evaluated and a specific reserve is assigned for the amount of the estimated probable credit loss. Total TDR loans, included in the impaired loan balances above, as of March 31, 2018 and December 31, 2017 , were $20.6 million and $20.3 million , respectively. TDR loans on accrual status amounted to $17.2 million and $17.4 million at March 31, 2018 and December 31, 2017 , respectively. TDR loans included in non-performing loans amounted to $3.4 million and $2.9 million at March 31, 2018 and December 31, 2017 , respectively. The Company continues to work with customers, particularly commercial relationships, and enters into loan modifications (which may or may not be TDRs) to the extent deemed to be necessary or appropriate while attempting to achieve the best mutual outcome given the individual financial circumstances and future prospects of the borrower. At March 31, 2018 , additional funding commitments for TDR loans was not material. The Company's obligation to fulfill the additional funding commitments on TDR loans is generally contingent on the borrower's compliance with the terms of the credit agreement. If the borrower is not in compliance, additional funding commitments may or may not be made at the Company's discretion. The following table sets forth the post modification balances of TDRs listed by type of modification for TDRs that occurred during the periods indicated. Three months ended March 31, 2018 March 31, 2017 (Dollars in thousands) Number of restructurings Amount Number of restructurings Amount Extended maturity date — — 2 3,063 Temporary payment reduction and payment re-amortization of remaining principal over extended term 2 139 1 374 Temporary interest only payment plan 2 132 1 94 Total 4 $ 271 4 $ 3,531 Amount of specific reserves included in the allowance for loan losses associated with TDRs listed above $ 120 $ — Loans modified as TDRs during the three month periods ended March 31, 2018 and March 31, 2017 by portfolio classification are detailed below. Three months ended March 31, 2018 March 31, 2017 (Dollars in thousands) Number of restructurings Pre-modification outstanding recorded investment Post-modification outstanding recorded investment Number of restructurings Pre-modification outstanding recorded investment Post-modification outstanding recorded investment Commercial real estate 2 $ 131 $ 132 1 $ 375 $ 374 Commercial and industrial 2 142 139 2 2,952 2,952 Commercial construction — — — 1 206 205 Residential mortgages — — — — — — Home equity loans and lines — — — — — — Consumer — — — — — — Total 4 $ 273 $ 271 4 $ 3,533 $ 3,531 There were no subsequent charge-offs associated with the new TDRs noted in the table above during the three months ended March 31, 2018 or 2017 . For the three month period ended March 31, 2018 , there were no payment defaults on loans modified as TDRs within the preceding twelve months. Payment defaults by portfolio classification, during the three month period ended March 31, 2017 on loans modified as TDRs within the preceding twelve months are detailed below. Three months ended March 31, 2017 (Dollars in thousands) Number of TDRs that defaulted Post- modification outstanding recorded investment Commercial real estate 3 $ 956 Commercial and industrial 1 231 Commercial construction — — Residential mortgages — — Home equity loans and lines — — Consumer — — Total 4 $ 1,187 Other real estate owned ( " OREO " ) The Company carried no OREO at March 31, 2018 , December 31, 2017 or March 31, 2017 . There were no additions, sales or write downs on OREO during the three months ended March 31, 2018 or 2017 . At March 31, 2018 , the Company had consumer mortgage loans secured by residential real estate properties for which formal foreclosure proceedings were in process according to local requirements of the applicable jurisdictions with carrying amounts totaling $234 thousand compared with $101 thousand at December 31, 2017 . Allowance for loan loss activity The allowance for loan losses is established through a provision for loan losses, a direct charge to earnings. Loan losses are charged against the allowance when management believes that the collectability of the loan principal is unlikely. Recoveries on loans previously charged-off are credited to the allowance. The allowance for loan losses amounted to $34.5 million at March 31, 2018 , compared to $32.9 million at December 31, 2017 , and $31.7 million at March 31, 2017 . For the three months ended March 31, 2018 and March 31, 2017 , the provision for loan losses amounted to $1.6 million and $125 thousand , respectively. The primary factor in the increase in the provision for loan losses for the three months ended March 31, 2018 compared to the same period in the prior year was an increase in the balance of the allowance for loan losses allocated to impaired and classified loans of $1.4 million for the three months ended March 31, 2018 , compared to a decrease of $390 thousand during the three months ended March 31, 2017 . The allowance for loan losses to total loans ratio was 1.51% at March 31, 2018 , 1.45% at December 31, 2017 and 1.53% at March 31, 2017 . Based on management's judgment as to the existing credit risks inherent in the loan portfolio, as discussed above under the heading "Credit Quality Indicators," management believes that the Company's allowance for loan losses is adequate to absorb probable losses from specifically known and other probable credit risks associated with the portfolio as of March 31, 2018 . Changes in the allowance for loan losses by portfolio classification for the three months ended March 31, 2018 are presented below: (Dollars in thousands) Cmml Real Estate Cmml and Industrial Cmml Constr Resid. Mortgage Home Equity Consumer Total Beginning Balance at December 31, 2017 $ 17,545 $ 9,669 $ 3,947 $ 904 $ 608 $ 242 $ 32,915 Provision 755 1,435 (664 ) 10 20 44 1,600 Recoveries — 108 — — 1 5 114 Less: Charge offs — 41 — — — 64 105 Ending Balance at March 31, 2018 $ 18,300 $ 11,171 $ 3,283 $ 914 $ 629 $ 227 $ 34,524 Ending allowance balance: Allocated to loans individually evaluated for impairment $ 52 $ 2,776 $ — $ 4 $ — $ 22 $ 2,854 Allocated to loans collectively evaluated for impairment $ 18,248 $ 8,395 $ 3,283 $ 910 $ 629 $ 205 $ 31,670 Changes in the allowance for loan losses by portfolio classification for the three months ended March 31, 2017 are presented below: (Dollars in thousands) Cmml Real Estate Cmml and Industrial Cmml Constr Resid. Mortgage Home Equity Consumer Total Beginning Balance at December 31, 2016 $ 14,902 $ 11,204 $ 3,406 $ 960 $ 634 $ 236 $ 31,342 Provision 316 (195 ) (42 ) 18 — 28 125 Recoveries 76 272 — — 1 3 352 Less: Charge offs — 103 — — — 33 136 Ending Balance at March 31, 2017 $ 15,294 $ 11,178 $ 3,364 $ 978 $ 635 $ 234 $ 31,683 Ending allowance balance: Allocated to loans individually evaluated for impairment $ 409 $ 1,928 $ 23 $ — $ — $ 14 $ 2,374 Allocated to loans collectively evaluated for impairment $ 14,885 $ 9,250 $ 3,341 $ 978 $ 635 $ 220 $ 29,309

Deposits

Deposits	3 Months Ended
	Mar. 31, 2018
Deposits [Abstract]
Deposits	Deposits Deposits are summarized as follows: (Dollars in thousands) March 31, 2018 December 31, 2017 Non-interest bearing demand deposits $ 717,656 $ 705,846 Interest-bearing checking 382,580 391,111 Savings 193,766 193,385 Money market 868,359 807,931 Certificates of deposit $250,000 or less 173,720 150,445 Certificates of deposit more than $250,000 49,814 45,154 Total customer deposits 2,385,895 2,293,872 Brokered deposits (1) 185,494 147,490 Total deposits $ 2,571,389 $ 2,441,362 ___________________________________ (1) Brokered CDs $250,000 and under. Total customer deposits (deposits excluding brokered deposits) include reciprocal money market deposits and CDs received from participating banks in nationwide deposit networks as a result of our customers electing to participate in Company offered programs which allow for enhanced FDIC insurance. Essentially, the equivalent of the customers' original deposited funds comes back to the Company as customer deposits within the appropriate category under total customer deposits. The Company's balances in these reciprocal products were $299.9 million and $249.6 million at March 31, 2018 and December 31, 2017 , respectively. See Note 12, "Fair Value Measurements," below for further information regarding the Company's fair value measurements for deposits.

Borrowed Funds and Subordinated

Borrowed Funds and Subordinated Debt	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Borrowed Funds and Subordinated Debt	Borrowed Funds and Subordinated Debt The Company had no borrowed funds at March 31, 2018 . At December 31, 2017 , borrowed funds consisted of FHLB borrowings amounting to $89.0 million . The Company had $14.9 million of outstanding subordinated debt (net of deferred issuance costs) at March 31, 2018 and $14.8 million at December 31, 2017 , which consisted of $15.0 million in aggregate principal amount of Fixed-to-Floating Rate Subordinated Notes (the "Notes") issued in January 2015 , with a 15 year term. The Notes are intended to qualify as Tier 2 capital for regulatory purposes and pay interest at a fixed rate of 6.00% per annum through January 30, 2025 , after which floating rates apply. Refer to Note 7, "Borrowed Funds and Subordinated Debt," to the Company's consolidated financial statements contained in the 2017 Annual Report on Form 10-K for additional information about the Company's subordinated debt. See Note 12, "Fair Value Measurements," below for further information regarding the Company's fair value measurements for borrowed funds and subordinated debt. See Note 2, "Investments," and Note 3, "Loans" above to these consolidated financial statements for further information regarding securities and loans pledged for borrowed funds. Refer to the "Liquidity" section in Item 2, "Management's Discussion and Analysis," for additional information about other sources of funding available to the Company.

Derivatives and Hedging Activit

Derivatives and Hedging Activities	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives and Hedging Activities	Derivatives and Hedging Activities Interest-rate lock commitments related to the origination of mortgage loans that will be sold are considered derivative instruments. The commitments to sell loans are also considered derivative instruments. The Company generally does not pool mortgage loans for sale, but instead, sells the loans on an individual basis. To reduce the net interest-rate exposure arising from its loan sale activity, the Company enters into the commitment to sell these loans at essentially the same time that the interest-rate lock commitment is quoted on the origination of the loan. The Company estimates the fair value of these derivatives based on current secondary mortgage market prices. At March 31, 2018 and December 31, 2017 , the estimated fair value of the Company's interest rate lock commitments and commitments to sell these mortgage loans were deemed immaterial. The Company may use interest rate contract swaps as part of its interest rate risk management strategy. Interest rate swap agreements may be entered into as hedges against future interest rate fluctuations on specifically identified assets or liabilities. The Company had no derivative fair value hedges or derivative cash flow hedges at March 31, 2018 or December 31, 2017 . The Company has a “Back-to-Back Swap” program whereby the Bank enters into an interest rate swap with a qualified commercial banking customer and simultaneously enters into an equal and opposite interest rate swap with a swap counterparty. The customer interest rate swap agreement allows commercial banking customers to convert a floating-rate loan payment to a fixed-rate payment. The transaction structure effectively minimizes the Bank’s net risk exposure resulting from such transactions. Customer-related credit risk is minimized by the cross collateralization of the loan and the interest rate swap agreement. Back-to-Back Swaps are not speculative; rather, the transactions result from a service the Company provides to certain commercial customers. Back-to-Back Swaps do not meet hedge accounting requirements and therefore changes in the fair value of both the customer swaps and the counterparty swaps, which have an offsetting relationship, are recognized directly in earnings. As a result of this offsetting relationship, there were no net gains or losses recognized in income on Back-to-Back Swaps during the three months ended March 31, 2018 or March 31, 2017 . Each Back-to-Back swap transaction consists of two interest-rate swaps (a customer swap and offsetting counterparty swap) and amounted to a total number of six interest rate swaps outstanding at both March 31, 2018 and December 31, 2017 , with an aggregate notional amount of $29.2 million and $29.4 million on those respective dates. Asset derivatives are included in the line item prepaid expenses and other assets and liability derivatives are included in the accrued expenses and other liabilities line item on the consolidated balance sheets, respectively. The table below presents the fair value and classification of the Company’s derivative financial instruments for the periods presented: As of March 31, 2018 As of December 31, 2017 (Dollars in thousands) Asset Derivatives Liability Derivatives Asset Derivatives Liability Derivatives Interest rate contracts - pay floating, received fixed $ — $ 887 $ 25 $ 568 Interest rate contracts - pay fixed, receive floating 887 — 543 — Total interest rate swaps $ 887 $ 887 $ 568 $ 568 By using derivative financial instruments, the Company exposes itself to counterparty-credit risk. Credit risk is the risk of failure by the counterparty to perform under the terms of the derivative contract. When the fair value of a derivative contract is positive, the counterparty owes the Company, which creates credit risk for the Company. When the fair value of a derivative is negative, the Company owes the counterparty and, therefore, it does not possess credit risk. The credit risk in derivative instruments is mitigated by entering into transactions with highly-rated counterparties that management believes to be creditworthy. The counterparty was rated A / A2 by S&P and Moody’s, respectively, at March 31, 2018 . Additionally, counterparty interest rate swaps contain provisions for collateral to be posted if the derivative exposure exceeds a threshold amount. The Company had credit risk exposure amounting to $887 thousand and $543 thousand at March 31, 2018 and December 31, 2017 , respectively, relating to interest rate swaps with counterparties. The Company held cash collateral of $930 thousand at March 31, 2018 and $480 thousand at December 31, 2017 . Collateral held by the Company is restricted and not considered an asset of the Company. Therefore, it is not carried on the Company's consolidated balance sheet. Interest rate swaps with the counterparty are subject to master netting agreements. The table below presents the Company's asset derivative positions and the potential effect of those netting arrangements on its financial position, as of the periods presented. Interest rate swaps with customers are not subject to master netting agreements and therefore are not included in the table below. As of March 31, 2018 (Dollars in thousands) Gross Amounts of Recognized Assets Gross Amounts Offset in the Statement of Financial Position Net Amounts of Assets Presented in the Statement of Financial Position Asset Derivatives Interest rate contracts - pay fixed, receive floating $ 887 $ — $ 887 As of December 31, 2017 (Dollars in thousands) Gross Amounts of Recognized Assets Gross Amounts Offset in the Statement of Financial Position Net Amounts of Assets Presented in the Statement of Financial Position Asset Derivatives Interest rate contracts - pay fixed, receive floating $ 568 $ 25 $ 543 The Company's interest rate swaps with counterparties contain credit-risk-related contingent provisions. These provisions provide the counterparty with the right to terminate its derivative positions and require the Company to settle its obligations under the agreements if the Company defaults on certain of its indebtedness. The Company also participates in loans originated by third party banks, where the originating bank utilizes a back-to-back interest rate swap structure; however, the Company is not a party to the swap agreements. Under the terms of the loan participations, the Company has accepted contingent liabilities that would only be realized if the swaps were terminated early and there were outstanding losses not covered by the underlying borrowers and the borrowers' pledged collateral. If applicable, the Company’s swap-loss exposure would be equal to the percentage of the Company’s participation in the underlying loan applied to the originating bank's swap loss. At March 31, 2018 and December 31, 2017 , the Company had two such participation loans and management considers the risk of material swap loss exposure to be unlikely based on the swap market value, as well as the borrower's financial and collateral strength.

Stockholder's Equity

Stockholder's Equity	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Stockholders' Equity	Stockholders' Equity Shares Authorized and Share Issuance The Company’s authorized capital is divided into common stock and preferred stock. The Company is authorized to issue 40,000,000 shares of common stock, with a par value of $0.01 , and as of March 31, 2018 had 11,682,914 shares issued and outstanding. The Company is authorized to issue 1,000,000 shares of preferred stock, with a par value of $0.01 . No preferred stock has been issued as of the date of this Form 10-Q. Holders of common stock are entitled to one vote per share, and are entitled to receive dividends if and when declared by the Company's Board of Directors (the "Board"). Dividend and liquidation rights of the common stock may be subject to the rights of any outstanding preferred stock. The Company has a shareholders rights plan. Under the plan, each share of common stock includes a right to purchase under certain circumstances one one-hundredth of a share of the Company’s Series A Junior Participating Preferred Stock, par value $0.01 per share, at a purchase price of $122.50 per one one-hundredth of a preferred share, subject to adjustment, or, in certain circumstances, to receive cash, property, shares of common stock or other securities of the Company. The rights are not presently exercisable and remain attached to the shares of common stock until the occurrence of certain triggering events that would ordinarily be associated with an unsolicited acquisition or attempted acquisition of 10% or more of the Company’s outstanding shares of common stock. The rights have no voting or dividend privileges, and unless and until they become exercisable, have no dilutive effect on the earnings of the Company. The rights will expire, unless earlier redeemed, exchanged, or otherwise rescinded by the Company, on January 13, 2028. The Company's stock incentive plans permit the Board to grant, under various terms, stock options (for the purchase of newly issued shares of common stock), restricted stock awards, restricted stock units and stock appreciation rights to officers and other employees, non-employee directors and consultants. The Company issues stock options and restricted stock awards to officers and other employees and restricted stock awards and stock compensation in lieu of cash fees to non-employee directors. The restricted stock awards allow for the non-forfeitable receipt of dividends, and the voting of all shares, whether or not vested, throughout the vesting periods at the same proportional level as common shares outstanding. The unvested restricted stock awards are the Company's only participating securities and are included in shares outstanding. Unvested participating restricted awards amounted to 121,999 shares and 117,219 shares as of March 31, 2018 and December 31, 2017 , respectively. Upon vesting, restricted stock awards may be net share-settled to cover payment for employee tax obligations, resulting in shares of common stock being reacquired by the Company and returned to the pool of shares reserved for issuance under the incentive plans. Chapter 156D of the Massachusetts General Laws, a statute known as the Massachusetts Business Corporation Act, which applies to Massachusetts corporations such as the Company, eliminates the concept of “treasury stock” and provides that shares a Massachusetts company reacquires will be treated as authorized but unissued shares. The Company's stock incentive plans also allow for newly issued shares of common stock to be issued without restrictions to officers and other employees, non-employee directors and consultants. From time to time, the Company issues shares to community members for consulting on regional advisory councils and grants shares of fully vested stock as employee anniversary awards. These shares vest immediately and the cost, which is deemed to be immaterial, is expensed in the period in which the services are rendered and is based on the market price on the date of grant. In addition to shares issued to employees, non-employee directors and community members for consulting on regional advisory councils, and shares issued through equity offerings, the Company maintains a dividend reinvestment and direct stock purchase plan (“DRSPP”) for stockholders and new investors to reinvest or purchase additional shares of common stock directly from the Company. See Note 10, "Stock-Based Compensation," below for additional information regarding the Company's stock incentive plans. See Note 11, "Earnings Per Share," below for additional information regarding unvested participating restricted awards and the Company's earnings per share calculation. Comprehensive Income Comprehensive income is defined as all changes to stockholders' equity except investments by and distributions to stockholders. Net income is one component of comprehensive income, with other components referred to in the aggregate as other comprehensive income. At March 31, 2018 , the Company's only other comprehensive income component is the net unrealized holding gains or losses on available-for-sale debt securities, net of deferred income taxes. Prior to the adoption of ASU 2016-01, other comprehensive income also included unrealized holding gains or losses on available-for-sale equity securities. Pursuant to GAAP, the Company initially excludes these unrealized holding gains and losses from net income; however, they are later reported as reclassifications out of accumulated other comprehensive income into net income when the debt securities are sold. When debt securities are sold, the reclassification of realized gains and losses on available-for-sale securities are included on the Consolidated Statements of Income under the "non-interest income" subheading on the line item "net gains on sales of investment securities" and the related income tax expense is included in the line item "provision for income taxes," both of which are also detailed on the Consolidated Statements of Comprehensive Income under the subheading "reclassification adjustment for net gains included in net income." Refer to Note 10, "Stockholders' Equity," to the Company's consolidated financial statements included in the Company's 2017 Annual Report on Form 10-K for additional information relating to capital adequacy requirements, dividends and the DRSPP.

Supplemental Retirement Plan an

Supplemental Retirement Plan and Other Postretirement Benefit Obligations	3 Months Ended
	Mar. 31, 2018
Retirement Benefits [Abstract]
Supplemental Retirement Plan and Other Postretirement Benefit Obligations	Supplemental Retirement Plan and Other Post-retirement Benefit Obligations Supplemental Employee Retirement Plan ("SERP") The Company has salary continuation agreements with two of its current executive officers and one former executive officer. These salary continuation agreements provide for predetermined fixed-cash supplemental retirement benefits to be provided for a period of 20 years after each individual reaches a defined "benefit age." The individuals covered under the SERP have reached the defined benefit age and are receiving payments under the plan. Additionally, the Company has not recognized service costs in the current or prior year as each officer had previously attained their individually defined benefit age and was fully vested under the plan. This non-qualified plan represents a direct liability of the Company, and as such has no specific assets set aside to settle the benefit obligation. The funded status is the aggregate amount accrued, or the "accumulated benefit obligation," which is equal to the present value of the benefits to be provided to the employee or any beneficiary. Because the Company's benefit obligations provide for predetermined fixed-cash payments, the Company does not have any unrecognized costs to be included as a component of accumulated other comprehensive income. Total net periodic benefit costs, comprised of interest costs only, were $26 thousand for the three months ended March 31, 2018 , compared to $29 thousand for the three months ended March 31, 2017 . Benefits paid amounted to $69 thousand for both the three months ended March 31, 2018 and March 31, 2017 . The Company anticipates accruing an additional $78 thousand to the SERP during the remainder of 2018 . Supplemental Life Insurance The Company has provided supplemental life insurance through split-dollar life insurance arrangements for certain executive and senior officers on whom the Bank owns bank-owned life insurance ("BOLI"). These arrangements provide a death benefit to the officer's designated beneficiaries that extend to postretirement periods for some of the supplemental life insurance plans. The Company has recognized a liability for these future postretirement benefits. These non-qualified plans represent a direct liability of the Company, and as such has no specific assets set aside to settle the benefit obligation. The funded status is the aggregate amount accrued, or the "accumulated postretirement benefit obligation," which is the present value of the post-retirement benefits associated with this arrangement. The following table illustrates the net periodic post-retirement benefit cost for the supplemental life insurance plans for the periods indicated: Three months ended March 31, (Dollars in thousands) 2018 2017 Service Cost $ (17 ) $ (3 ) Interest Cost 62 23 Net periodic benefit cost $ 45 $ 20

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	Stock-Based Compensation The Company currently has two individual stock incentive plans: the 2009 plan, as amended in 2015, and the 2016 plan. As of March 31, 2018 , an aggregate of 409,301 shares remain available for future grants under the plans. The Company's stock-based compensation expense related to these plans includes stock options and stock awards to officers and other employees included in salary and benefits expense, and stock awards and stock compensation in lieu of cash fees to non-employee directors both included in other operating expenses. Total stock-based compensation expense was $385 thousand for the three months ended March 31, 2018 , compared to $324 thousand for the three months ended March 31, 2017 . A tax benefit associated with employee exercises and vesting of stock compensation of approximately $195 thousand was recorded as a reduction of the Company's income tax expense for the three months ended March 31, 2018 , compared with $667 thousand for the three months ended March 31, 2017 . These amounts, treated as discrete tax items in the period in which they occur, will vary from year to year as a function of the volume of share-based payments vested or exercised and the then current market price of the Company's stock in comparison to the compensation cost recognized in the Company's consolidated financial statements. Stock Option Awards The Company recognized stock-based compensation expense related to stock option awards of $51 thousand for the three months ended March 31, 2018 , compared to $62 thousand for the three months ended March 31, 2017 . The table below provides a summary of the options granted, including the fair value as a percentage of the market value of the stock at the date of grant and the average assumptions used during the periods indicated: Three Months Ended March 31, 2018 2017 Options granted 14,755 15,009 Term in years 10 10 Weighted average assumptions used in the fair value model: Expected volatility 37 % 40 % Expected dividend yield 2.10 % 2.09 % Expected life in years 6.5 7 Risk-free interest rate 2.86 % 2.35 % Weighted average market price on date of grants $ 34.33 $ 30.46 Per share weighted average fair value $ 11.98 $ 11.34 Fair value as a percentage of market value at grant date 35 % 37 % Options granted during the first three months of 2018 and 2017 generally vest 50% in year two and 50% in year four, on the anniversary date of the awards. The Company utilizes the Black-Scholes option valuation model in order to determine the per share grant date fair value of option grants. Stock Awards Stock-based compensation expense recognized in association with stock awards amounted to $259 thousand for the three months ended March 31, 2018 , compared to $187 thousand for the three months ended March 31, 2017 . Restricted stock awards are granted at the market price on the date of the grant. Employee awards generally vest over four years in equal portions beginning on or about the first anniversary date of the award or are performance based awards that vest upon the Company achieving certain predefined performance objectives. Non-employee director awards generally vest over two years in equal portions beginning on or about the first anniversary date of the award. The table below provides a summary of restricted stock awards granted during the periods indicated: Three Months Ended March 31, Restricted Stock Awards (no. of underlying shares) 2018 2017 Two year vesting 7,280 6,944 Four year vesting 16,666 16,253 Performance-based vesting 20,559 25,623 Total restricted stock awards 44,505 48,820 Weighted average grant date fair value $ 34.33 $ 30.46 Stock in Lieu of Directors' Fees In addition to restricted stock awards discussed above, the non-employee members of the Company's Board of Directors may opt to receive newly issued shares of the Company's common stock in lieu of cash compensation for attendance at Board and Board Committee meetings. Stock-based compensation expense related to these directors' fees amounted to $75 thousand for both the three months ended March 31, 2018 and the three months ended March 31, 2017 , and is included in other operating expenses. In January 2018 , non-employee directors were issued 7,326 shares of common stock in lieu of 2017 annual cash fees of $281 thousand at a market value price of $38.39 per share, the market value of the common stock on the opt-in measurement date of January 3, 2017 . For further information regarding the Company's stock awards, see Note 8, "Stockholders' Equity," above under the caption "Shares authorized and share issuance." There have been no material changes to the terms of the Company's stock incentive plans or the terms for vesting, forfeiture and settlement for options and restricted stock awards granted and outstanding under such plans as reported in the 2017 Annual Report on Form 10-K. Refer to Note 12 "Stock-Based Compensation Plans," in the Company's 2017 Annual Report on Form 10-K for further information on the Company's stock incentive plans, stock options and restricted awards including descriptions of the assumptions used in the valuation model for stock options.

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Earnings Per Share	Earnings per Share Basic earnings per share are calculated by dividing net income available to common stockholders by the weighted average number of common shares outstanding (including participating securities) during the year. The Company's only participating securities are unvested restricted stock awards that contain non-forfeitable rights to dividends. See Note 8, "Stockholders' Equity," under the caption "Shares authorized and share issuance," above for further information regarding the Company's participating securities. Diluted earnings per share reflects the effect on weighted average shares outstanding of the number of additional shares outstanding if dilutive stock options were converted into common stock using the treasury stock method. The table below presents the increase in average shares outstanding, using the treasury stock method, for the diluted earnings per share calculation for the periods indicated: Three months ended March 31, 2018 2017 Basic weighted average common shares outstanding 11,628,587 11,508,811 Dilutive shares 72,267 90,051 Diluted weighted average common shares outstanding 11,700,854 11,598,862 There were 29,353 options outstanding that were determined to be anti-dilutive and therefore excluded from the calculation of dilutive shares for the three months ended March 31, 2018 . These options, which were not dilutive at that date, may potentially dilute earnings per share in the future.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The FASB defines the fair value of an asset or liability to be the price which a seller would receive in an orderly transaction between market participants (an exit price) and also establishes a fair value hierarchy segregating fair value measurements using three levels of inputs: (Level 1) quoted market prices in active markets for identical assets or liabilities; (Level 2) significant other observable inputs, including quoted prices for similar items in active markets, quoted prices for identical or similar items in markets that are not active, inputs such as interest rates and yield curves, volatilities, prepayment speeds, credit risks and default rates which provide a reasonable basis for fair value determination or inputs derived principally from observed market data; and (Level 3) significant unobservable inputs for situations in which there is little, if any, market activity for the asset or liability. Unobservable inputs must reflect reasonable assumptions that market participants would use in pricing the asset or liability, which are developed on the basis of the best information available under the circumstances. The following tables summarize significant assets and liabilities carried at fair value and placement in the fair value hierarchy at the dates specified: March 31, 2018 Fair Value Measurements using: (Dollars in thousands) Fair Value (Level 1) (Level 2) (Level 3) Assets measured on a recurring basis: Debt securities $ 412,213 $ — $ 412,213 $ — Equity securities 295 295 — — FHLB stock 2,370 — — 2,370 Interest rate swaps 887 — 887 — Assets measured on a non-recurring basis: Impaired loans (collateral dependent) 2,424 — — 2,424 Liabilities measured on a recurring basis: Interest rate swaps $ 887 $ — $ 887 $ — December 31, 2017 Fair Value Measurements using: (Dollars in thousands) Fair Value (Level 1) (Level 2) (Level 3) Assets measured on a recurring basis: Debt securities $ 405,206 $ — $ 405,206 $ — FHLB stock 5,215 — — 5,215 Interest rate swaps 568 — 568 — Assets measured on a non-recurring basis: Impaired loans (collateral dependent) 2,696 — — 2,696 Liabilities measured on a recurring basis: Interest rate swaps $ 568 $ — $ 568 $ — The Company did not transfer any assets between the fair value measurement levels during the three months ended March 31, 2018 or the year ended December 31, 2017 . All of the Company's debt securities are considered "available-for-sale" and are carried at fair value. The debt security category above includes federal agency obligations, commercial and residential federal agency MBS, municipal securities, corporate bonds and certificates of deposits, as held at those dates. The Company utilizes third-party pricing vendors to provide valuations on its debt securities. Fair values provided by the vendors were generally determined based upon pricing matrices utilizing observable market data inputs for similar or benchmark securities in active markets and/or based on a matrix pricing methodology which employs The Bond Market Association's standard calculations for cash flow and price/yield analysis, live benchmark bond pricing and terms/condition data available from major pricing sources. Therefore, management regards the inputs and methods used by third-party pricing vendors to be "Level 2 inputs and methods" as defined in the "fair value hierarchy." The Company periodically obtains a second price from an impartial third party on debt securities to assess the reasonableness of prices provided by the primary independent pricing vendor. The Company's equity portfolio fair value is measured based on quoted market prices for the shares; therefore, these securities are categorized as Level 1 within the fair value hierarchy. The Bank is required to purchase FHLB stock at par value in association with advances from the FHLB; this stock is classified as a restricted investment and carried at cost which management believes approximates fair value; therefore, these securities are categorized as Level 3 measures. See Note 1, "Summary of Significant Accounting Policies," Item (c) "Restricted Instruments" for further information regarding the Company's fair value assessment of FHLB capital stock. Impaired loan balances in the table above represent those collateral dependent impaired commercial loans where management has estimated the probable credit loss by comparing the loan's fair value against the expected realizable fair value of the collateral (appraised value, or internal analysis less estimated cost to sell, adjusted as necessary for changes in relevant valuation factors subsequent to the measurement date). Certain inputs used in these assessments, and possible subsequent adjustments, are not always observable, and therefore, collateral dependent impaired loans are categorized as Level 3 within the fair value hierarchy. A specific allowance is assigned to the collateral dependent impaired loan for the amount of management's estimated probable credit loss. The specific allowances assigned to the collateral dependent impaired loans amounted to $1.4 million at March 31, 2018 compared to $872 thousand at December 31, 2017 . The fair values for the interest rate swap assets and liabilities represent a FASB Level 2 measurement and are based on settlement values adjusted for credit risks and observable market interest rate curves. The settlement values are based on discounted cash flow analysis, a widely accepted valuation technique, reflecting the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate curves. Credit risk adjustments consider factors such as the likelihood of default by the Company and its counterparties, its net exposures and remaining contractual life. The change in value of interest rate swap assets and liabilities attributable to credit risk was not significant during the reported periods. Refer also to Note 7, "Derivatives and Hedging Activities," for additional information on the Company's interest rate swaps. Letters of credit are conditional commitments issued by the Company to guarantee the financial obligation or performance of a customer to a third party. The fair value of these commitments was estimated to be the fees charged to enter into similar agreements, and accordingly these fair value measures are deemed to be FASB Level 2 measurements. In accordance with the FASB, the estimated fair values of these commitments are carried on the consolidated balance sheet as a liability and amortized to income over the life of the letters of credit, which are typically one year. The estimated fair value of these commitments carried on the consolidated balance sheet at March 31, 2018 and December 31, 2017 were deemed immaterial. Interest rate lock commitments related to the origination of mortgage loans that will be sold are considered derivative instruments. The commitments to sell loans are also considered derivative instruments. The Company generally does not pool mortgage loans for sale, but instead sells the loans on an individual basis. To reduce the net interest rate exposure arising from its loan sale activity, the Company enters into the commitment to sell these loans at essentially the same time that the interest rate lock commitment is quoted on the origination of the loan. The Company estimates the fair value of these derivatives based on current secondary mortgage market prices. These commitments are accounted for in accordance with FASB guidance. The fair values of the Company's derivative instruments are deemed to be FASB Level 2 measurements. At March 31, 2018 and December 31, 2017 , the estimated fair value of the Company's interest rate lock commitments and commitments to sell these mortgages loans were deemed immaterial. The following table presents additional quantitative information about assets measured at fair value on a recurring and non-recurring basis for which the Company utilized Level 3 inputs (significant unobservable inputs for situations in which there is little, if any, market activity for the asset or liability) to determine fair value as of March 31, 2018 : (Dollars in thousands) Fair Value Valuation Technique Unobservable Input Unobservable Input Value or Range Assets measured on a recurring basis: FHLB stock $ 2,370 FHLB Stated Par Value N/A N/A Assets measured on a non-recurring basis: Impaired loans (collateral dependent) $ 2,424 Appraisal of collateral Appraisal adjustments (1) 5% - 50% __________________________________________ (1) Appraisals may be adjusted by management for qualitative factors such as economic conditions and estimated liquidation expenses. Estimated Fair Values of Assets and Liabilities In addition to disclosures regarding the measurement of assets and liabilities carried at fair value on the consolidated balance sheet, the Company is also required to disclose fair value information about financial instruments for which it is practicable to estimate that value, whether or not recognized on the consolidated balance sheet. The carrying values, estimated fair values and placement in the fair value hierarchy of the Company's consolidated financial instruments for which fair value is only disclosed but not recognized on the consolidated balance sheet at the dates indicated are summarized as follows: March 31, 2018 Fair value measurement (Dollars in thousands) Carrying Amount Fair Value Level 1 Inputs Level 2 Inputs Level 3 Inputs Financial assets: Loans, net $ 2,255,649 $ 2,237,319 $ — $ — $ 2,237,319 Financial liabilities: Certificates of deposit (including brokered) 409,028 406,487 — 406,487 — Subordinated debt 14,850 13,949 — — 13,949 December 31, 2017 Fair value measurement (Dollars in thousands) Carrying Amount Fair Value Level 1 Inputs Level 2 Inputs Level 3 Inputs Financial assets: Loans held for sale $ 208 $ 208 $ — $ 208 $ — Loans, net 2,236,989 2,236,169 — — 2,236,169 Financial liabilities: Certificates of deposit (including brokered) 343,089 341,765 — 341,765 — Borrowed funds 89,000 88,996 — 88,996 — Subordinated debt 14,847 14,208 — — 14,208 Excluded from the tables above are certain financial instruments with carrying values that approximated their fair value at the dates indicated, as they were short-term in nature or payable on demand. These include cash and cash equivalents, and non-term deposit accounts. The respective carrying values of these instruments would all be considered to be classified within Level 1 of their fair value hierarchy. Also excluded from these tables are the fair values of commitments for unused portions of lines of credit and commitments to originate loans that were short-term, at current market rates and estimated to have no significant change in fair value.

Summary of Significant Accoun21

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Principles of Consolidation	The accompanying unaudited consolidated interim financial statements and these notes should be read in conjunction with the December 31, 2017 audited consolidated financial statements and notes thereto contained in the 2017 Annual Report on Form 10-K of Enterprise Bancorp, Inc. as filed with the Securities and Exchange Commission (the "SEC") on March 13, 2018 (the " 2017 Annual Report on Form 10-K"). The accompanying unaudited consolidated interim financial statements of Enterprise Bancorp, Inc. (the "Company," "Enterprise," "we," or "our"), a Massachusetts corporation, include the accounts of the Company and its wholly owned subsidiary, Enterprise Bank and Trust Company, commonly referred to as Enterprise Bank (the "Bank"). The Bank is a Massachusetts trust company and state chartered commercial bank organized in 1989. Substantially all of the Company's operations are conducted through the Bank and its subsidiaries. The Company has not changed its accounting policies from those disclosed in its 2017 Annual Report on Form 10-K. The Bank's subsidiaries include Enterprise Insurance Services, LLC and Enterprise Wealth Services, LLC, organized under the laws of the State of Delaware for the purposes of engaging in insurance sales activities and offering non-deposit investment products and services, respectively. In addition, the Bank has the following subsidiaries that are incorporated in the Commonwealth of Massachusetts and classified as security corporations in accordance with applicable Massachusetts General Laws: Enterprise Security Corporation; Enterprise Security Corporation II; and Enterprise Security Corporation III. The security corporations, which hold various types of qualifying securities, are limited to conducting securities investment activities that the Bank itself would be allowed to conduct under applicable laws. At March 31, 2018 , the Company had 24 full service branch banking offices serving the Greater Merrimack Valley and North Central regions of Massachusetts and Southern New Hampshire (Southern Hillsborough and Rockingham counties). Through the Bank and its subsidiaries, the Company offers a range of commercial, residential and consumer loan products, deposit products and cash management services and electronic banking options, as well as insurance services. The Company also provides a range of investment advisory, wealth management and trust services delivered via two channels, Enterprise Wealth Management and Enterprise Wealth Services. The services offered through the Bank and its subsidiaries are managed as one strategic unit and represent the Company's only reportable operating segment. The Federal Deposit Insurance Corporation (the "FDIC") and the Massachusetts Division of Banks (the "Division") have regulatory authority over the Bank. The Bank is also subject to certain regulatory requirements of the Board of Governors of the Federal Reserve System (the "Federal Reserve Board") and, with respect to its New Hampshire branch operations, the New Hampshire Banking Department. The business and operations of the Company are subject to the regulatory oversight of the Federal Reserve Board. The Division also retains supervisory jurisdiction over the Company.
Basis of Accounting	The accompanying unaudited consolidated interim financial statements and notes thereto have been prepared in accordance with U.S. generally accepted accounting principles ("GAAP") for interim financial information and the instructions for SEC Form 10-Q through the rules and interpretive releases of the SEC under federal securities law. In the opinion of management, the accompanying unaudited consolidated interim financial statements reflect all necessary adjustments consisting of normal recurring accruals for a fair presentation. All significant intercompany balances and transactions have been eliminated in the accompanying unaudited consolidated interim financial statements. Interim results are not necessarily indicative of results to be expected for the entire year, or any future period.
Reclassifications	Certain previous years' amounts in the consolidated financial statements, and notes thereto, have been reclassified to conform to the current year's presentation.
Subsequent events	The Company has evaluated subsequent events and transactions from March 31, 2018 through the date this Quarterly Report on Form 10-Q was filed with the SEC for potential recognition or disclosure as required by GAAP and determined that there were no material subsequent events requiring recognition or disclosure.
Critical Accounting Estimates	In preparing the unaudited consolidated interim financial statements in conformity with GAAP, management is required to exercise judgment in determining many of the methodologies, assumptions and estimates to be utilized. These assumptions and estimates affect the reported values of assets and liabilities as of the balance sheet date and income and expenses for the period then ended. As future events and their effects cannot be determined with precision, actual results could differ significantly from these estimates should the assumptions and estimates used change over time due to changes in circumstances. Changes in those estimates resulting from continuing change in the economic environment and other factors will be reflected in the consolidated financial statements and results of operations in future periods. As discussed in the Company's 2017 Annual Report on Form 10-K, the three most significant areas in which management applies critical assumptions and estimates are the estimates of the allowance for loan losses, impairment review of investment securities and the impairment review of goodwill. Refer to Note 1, "Summary of Significant Accounting Policies," to the Company's consolidated financial statements included in the Company's 2017 Annual Report on Form 10-K for accounting policies related to these significant estimates. The Company has not changed its significant accounting policies from those disclosed in its 2017 Annual Report on Form 10-K.
Restricted Instruments	Restricted Instruments Certain of the Company's derivative agreements contain provisions for collateral to be posted if the derivative exposure exceeds a threshold amount. When the Company has pledged cash as collateral for this purpose, the cash is carried as restricted cash within cash and cash equivalents. See Note 7, "Derivatives and Hedging Activities" for more information about the Company's collateral related to its derivatives. The Bank is also required by the Federal Reserve Bank of Boston (the "FRB") to maintain in reserves certain amounts of vault cash and/or deposits with the FRB. The average daily reserve requirement included in “Cash and Due from Banks” was approximately $9.3 million , based on the two week computation period encompassing March 31, 2018 . As a member of the Federal Home Loan Bank of Boston (the "FHLB"), the Company is required to purchase certain levels of FHLB capital stock at par value in association with outstanding advances from the FHLB. From time-to-time, the FHLB may initiate the repurchase, at par value, of "excess" levels of its capital stock held by member banks. This stock is classified as a restricted investment and carried at cost, which management believes approximates fair value. FHLB stock represents the only restricted investment held by the Company. Management regularly reviews its holdings of FHLB stock for other-than-temporary-impairment ("OTTI"). Based on management's periodic review, the Company has not recorded any OTTI charges on this investment to date. If it was determined that a write-down of FHLB stock was required, impairment would be recognized through a charge to earnings. See Note 2, "Investment Securities," for additional information on management's OTTI review.
Revenue Recognition	Revenue Recognition-Accounting Standard Codification (“ASC”) Topic 606 On January 1, 2018, the Company adopted ASC No. 2014-09, "Revenue from Contracts with Customers-Topic 606." The core principles require an entity to recognize revenue to depict the transfer of goods and services to customers as performance obligations are satisfied. While the majority of the Company’s revenue is generated from contracts with customers, our primary sources of revenue, interest and dividend income (primarily loan interest income), are outside of the scope of ASC 606 and accounted for under other ASC topics. We have not identified any material changes needed in our process of recording revenue or any income statement reclassifications necessary upon the adoption of the new revenue recognition standard. The primary areas of non-interest income on the Company's Consolidated Statements of Income that are within the scope of ASC 606 are discussed below. Investment advisory fees consists of income generated through Enterprise Wealth Management and Enterprise Wealth Services. Enterprise Wealth Management income is primarily generated by managing customer’s financial assets. Revenue is recognized under the accrual basis when our performance obligation is completed each month. Payment is typically received in the month following the service and the accrual is reversed. Enterprise Wealth Services revenue is generated through a third-party arrangement to refer, manage and service customers. For new sales and referrals along with transactional type charges, the performance obligation is based on a point in time and the payment is received and revenue is recognized in the same month as the revenue generating activity. For managing and servicing customers, revenue is recognized when our performance obligation is completed each month, which is generally the time the payment is received. Deposit and interchange fees are comprised of deposit account related charges and interchange income. Deposit fees consist of fees for accounts on analysis and monthly service charges, as well as transactional fees such as overdraft fees. Analysis and monthly services fees are recognized over the period the service is performed and payment is generally charged to customer’s account at the end of the month or in the following month with material amounts accrued if necessary. For transactional fees, the performance obligation and the revenue is recognized at a point of time and payment is typically received as the service is rendered. Interchange income is generated primarily from retail debit card transactions processed through the card payment network. The performance obligation and the revenue are recognized when the service is performed and payment is received as services are rendered. The following non-interest income components are not subject to ASC 606: Income on bank-owned life insurance, Net gains on sales of investment securities, and Net gains on sales of loans, and are covered under other ASC topics. The remaining revenue items in Non-interest income are not material. For further information on the Company's adoption of Accounting Standards Update ("ASU") 2014-09, "Revenue from Contracts with Customers (Topic 606), see Item (f) "Recent Accounting Pronouncements" under the subheading "Accounting pronouncements adopted by the Company" below in this Note 1. See also the Company's most recent 2017 Annual Report on Form 10-K Note 1, "Summary of Significant Accounting Policies," to the Company's consolidated financial statements for additional accounting policies on revenue recognition related to loans, investments, gains and losses on debt security sales, and net gains on loans held for sale.
Income Taxes	Income Taxes The Company and its subsidiaries file income tax returns in the U.S. federal jurisdiction and in the states of Massachusetts and New Hampshire within the directives of the respective enacted tax legislation. The Company uses the asset and liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are recognized for the future tax expense or benefit attributable to differences between the financial statement carrying amounts and the tax basis of assets and liabilities. The deferred tax assets and liabilities are reflected at currently enacted income tax rates applicable to the period in which the deferred tax assets or liabilities are expected to be realized or settled. As changes in tax laws or rates are enacted, deferred tax assets and liabilities will be adjusted accordingly through the provision for income taxes in the period that includes the enactment date. The Company's policy is to classify interest resulting from underpayment of income taxes as income tax expense in the first period the interest would begin accruing according to the provisions of the relevant tax law. The Company classifies penalties resulting from underpayment of income taxes as income tax expense in the period for which the Company claims or expects to claim an uncertain tax position or in the period in which the Company's judgment changes regarding an uncertain tax position. The income tax provisions will differ from the expense that would result from applying the federal statutory rate to income before taxes, due primarily to the impact of tax-exempt interest from certain investment securities, loans and bank-owned life insurance ("BOLI"). The Company did not have any unrecognized tax benefits accrued as income tax liabilities or receivables or as deferred tax items at March 31, 2018 . The Company is subject to U.S. federal and state income tax examinations by taxing authorities for the 2014 through 2017 tax years.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Accounting pronouncements adopted by the Company In May 2014, the Financial Accounting Standards Board ("FASB ") issued Accounting Standards Update ("ASU") No. 2014-09, "Revenue from Contracts with Customers (Topic 606)." This ASU is intended to create a single source of revenue guidance which is more principles based than current revenue guidance. The guidance affects any entity that either enters into contracts with customers to transfer goods or services, or enters into contracts for the transfer of non-financial assets, unless those contracts are within the scope of other standards. In the first quarter of 2018, the Company adopted ASU 2014-09. Because the largest portion of the Company's revenue, interest income and various loan fees, is specifically excluded from the scope of this ASU, and because the Company recognizes the majority of the remaining revenue sources in a manner that is consistent with this ASU, the adoption of this standard did not materially impact the Company's consolidated financial statements, results of operations or disclosures. For further information regarding the Company's revenue policies see Item (d) "Revenue Recognition-Accounting Standard Codification (“ASC”) Topic 606" above in this Note 1. 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," which updates certain aspects of recognition, measurement, presentation and disclosure of financial instruments. Among other things, ASU No. 2016-01: • Requires equity investments (except 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; • Requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; and • 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. The FASB has since issued an additional related ASU amendment intended to clarify certain aspects and improve understanding of the implementation guidance in ASU No. 2016-01 but does not change the core principles of the original guidance. This ASU is effective for public companies for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Because the Company's investment in equity securities at March 31, 2018 was immaterial, the adoption of this ASU by the Company in the first quarter of 2018 did not have a material impact on the Company's consolidated financial statements, results of operations or disclosures. The fair value changes of equity securities that will be recognized in net income in the future will depend on the amount of dollars invested and the magnitude of changes in equity market values. For further information regarding the Company's recognition and measurement of financial assets and liabilities see Note 2, "Investment Securities," and Note 12, "Fair Value Measures" in this Form 10-Q. In August 2016, the FASB issued ASU No. 2016-15, "Statement of Cash flows (Topic 230) - Classification of Certain Cash Receipts and Cash Payments." The amendments are intended to reduce diversity in practice related to the presentation of eight specific cash flow issues. For public business entities that are SEC filers, such as the Company, the amendments in this Update are effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Because this amendment primarily impacts the presentation and classification of information, this ASU did not materially impact the Company's consolidated financial statements and results of operations upon adoption in the first quarter of 2018. In November 2016, the FASB issued ASU No. 2016-18, "Statement of Cash flows-Restricted Cash (Topic 230)." The amendments in this Update clarify the inclusion of restricted cash in the cash and cash equivalents beginning-of-period and end-of period reconciliation on the statement of cash flows. For public business entities that are SEC filers, such as the Company, the amendments in this Update are effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Because this amendment primarily impacts the presentation and classification of information, this ASU did not have a significant impact on the Company's consolidated financial statements and results of operations upon adoption in the first quarter of 2018. For further information regarding the Company's restricted cash see Item (c) "Restricted Instruments" above in this Note 1. In March 2017, the FASB issued ASU No. 2017-07, "Compensation-Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost." The amendments in this Update outline the presentation, classification and disclosure requirements for service cost and other components of net benefit costs. For public business entities that are SEC filers, such as the Company, the amendments in this Update are effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Because this amendment primarily impacts the presentation and classification of information, the adoption of this ASU in the first quarter of 2018 did not have a material impact on the Company's consolidated financial statements and results of operations. For further information regarding the Company's compensation retirement benefits see Note 9, "Supplemental Retirement Plans and Other Post-retirement Benefit Obligations" In May 2017, the FASB issued ASU No. 2017-09, "Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting." The amendments in this Update apply to entities that change the terms of an outstanding share-based payment award. The amendments are intended to reduce diversity in practice as well as cost and complexity when applying guidance in Topic 718 to the modification of the terms and conditions of a share-based payment award. This ASU provides guidance on the three modifications to share-based payment awards and conditions that must be met in order to exempt an entity from modification accounting under topic 718. The amendments in this Update apply prospectively to award modifications on or after the adoption date, and are effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The adoption of this ASU in the first quarter of 2018 did not have an impact on the Company's consolidated financial statements, results of operations or disclosures because to date the Company has not made any such modifications. For further information regarding the Company's stock compensation see Note 10, "Stock-Based Compensation" Accounting pronouncements not yet adopted by the Company (in order of effective date of implementation) In February 2016, the FASB issued ASU No. 2016-02, "Leases (Topic 842)," which supersedes previous leasing guidance in Topic 840, Leases. Under the new guidance, lessees are required to recognize lease assets and lease liabilities on the balance sheet for all leases with terms longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. The new standard is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. A modified retrospective transition approach is required for lessees for capital and operating leases existing at, or entered into after, the beginning of the earliest comparative period presented in the consolidated financial statements, with certain practical expedients available. The Company is currently evaluating the effects of this ASU on the Company's consolidated financial statements, results of operations and disclosures. Based on the Company's evaluation to date, management believes the more significant implication of this ASU on the Company relates to operating leases of our facilities, mainly branch leases. As of March 31, 2018 , the Company had leases on 17 of its locations, including branches and part of its main campus, and expects that upon adoption of this ASU the balance sheet will reflect both lease liabilities, equal to the present value of lease payments, and right-of-use assets, equal to the lease liability plus payments made to lessors adjusted for prepaid or accrued rent and any initial direct cost incurred. In addition, the Company will recognize lease expense in the income statement on a straight-line basis similar to current operating leases. The straight-line expense will reflect the interest expense on the lease liability (effective interest method) and amortization of the right-of-use asset. Lease expense will be presented as a single line item in the operating expense section of the income statement. Management believes that lease expense under the new standard will generally approximate lease expense under current GAAP. The foregoing observations are subject to change as management completes their evaluation. In June 2016, the FASB issued ASU No. 2016-13, "Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments." The amendments in this ASU require a financial asset (or a group of financial assets) measured at amortized cost basis to be presented at the net amount expected to be collected. Previously, when credit losses were measured under GAAP, an entity generally only considered past events and current conditions in measuring the incurred loss and generally recognition of the full amount of credit losses was delayed until the loss was probable of occurring. The amendments in this ASU eliminate the probable initial recognition threshold in current GAAP and, instead, reflect an entity’s current estimate of all expected credit losses (commonly known as "CECL"). The measurement of expected credit losses is based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. An entity must use judgment in determining the relevant information and estimation methods that are appropriate in its circumstances. The income statement reflects the measurement of credit losses for newly recognized financial assets, as well as the expected increases or decreases of expected credit losses that have taken place during the period. The allowance for credit losses is a valuation account that is deducted from the amortized cost basis of the financial asset(s) to present the net fair value at the amount expected to be collected on the financial asset. Credit losses on available-for-sale debt securities should be measured in a manner similar to current GAAP. However, the amendments in this Update require that credit losses be presented as an allowance rather than as a write-down. Unlike current GAAP, the ASU provides for reversals of credit losses in future period net income in situations where the estimate of loss declines. An entity will apply the amendments in this Update through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective (that is, a modified-retrospective approach). For public business entities that are SEC filers, such as the Company, the amendments in this Update are effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption for fiscal years beginning after December 15, 2018 is permitted. In April, 2018, banking regulators issued a proposed revision to their capital rules that addresses the regulatory capital treatment of credit loss allowances under the CECL methodology and, if enacted as proposed, would allow banking organizations to phase in the day-one regulatory capital effects of CECL adoption over three years. The Company has established an implementation committee and an enterprise-wide implementation plan for this ASU, which will consider the impact to operations, financial results, capital, and disclosures and controls. At present, the impact of the adoption of ASU No. 2016-13 on the Company's operations, financial results, disclosures, and controls is unknown. In January 2017, the FASB issued ASU No. 2017-04, "Intangibles-Goodwill and Other (Topic 350)-Simplifying the Test for Goodwill Impairment." The main provision in this ASU eliminated Step 2 of the goodwill impairment test and instead requires an entity to perform its annual, or interim, goodwill impairment test by comparing the fair value of the reporting unit with its carrying amount. An impairment charge would be recognized for the amount the carrying value exceeds the reporting unit's fair value as long as the amount recognized doesn't exceed the amount of goodwill allocated to the reporting unit. For public business entities that are SEC filers, such as the Company, the amendments in this Update are effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted for impairment tests performed on testing dates after January 1, 2017. Goodwill carried on the Company’s consolidated financial statements was $5.7 million at both March 31, 2018 and December 31, 2017 . This asset is related to the Company’s acquisition of two branch offices in July 2000. The Company does not expect the adoption of ASU No. 2017-01 to have a material impact on the Company's consolidated financial statements and results of operations.

Stockholder's Equity (Policies)

Stockholder's Equity (Policies)	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Comprehensive Income	Comprehensive income is defined as all changes to stockholders' equity except investments by and distributions to stockholders. Net income is one component of comprehensive income, with other components referred to in the aggregate as other comprehensive income. At March 31, 2018 , the Company's only other comprehensive income component is the net unrealized holding gains or losses on available-for-sale debt securities, net of deferred income taxes. Prior to the adoption of ASU 2016-01, other comprehensive income also included unrealized holding gains or losses on available-for-sale equity securities. Pursuant to GAAP, the Company initially excludes these unrealized holding gains and losses from net income; however, they are later reported as reclassifications out of accumulated other comprehensive income into net income when the debt securities are sold. When debt securities are sold, the reclassification of realized gains and losses on available-for-sale securities are included on the Consolidated Statements of Income under the "non-interest income" subheading on the line item "net gains on sales of investment securities" and the related income tax expense is included in the line item "provision for income taxes," both of which are also detailed on the Consolidated Statements of Comprehensive Income under the subheading "reclassification adjustment for net gains included in net income."

Investment Securities (Tables)

Investment Securities (Tables)	3 Months Ended
	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Schedule of Available-for-Sale Investments Reconciliation	The amortized cost and fair values of debt securities at the dates specified are summarized as follows: March 31, 2018 (Dollars in thousands) Amortized cost Unrealized gains Unrealized losses Fair Value Federal agency obligations (1) $ 51,802 $ — $ 417 $ 51,385 Residential federal agency MBS (1) 154,739 5 3,627 151,117 Commercial federal agency MBS (1) 66,653 — 1,799 64,854 Municipal securities 134,306 495 1,942 132,859 Corporate bonds 11,326 6 276 11,056 Certificates of deposits (2) 950 — 8 942 Total debt securities, at fair value $ 419,776 $ 506 $ 8,069 $ 412,213 December 31, 2017 (Dollars in thousands) Amortized cost Unrealized gains Unrealized losses Fair Value Federal agency obligations (1) $ 51,769 $ 30 $ 82 $ 51,717 Residential federal agency MBS (1) 141,054 71 971 140,154 Commercial federal agency MBS (1) 66,777 9 286 66,500 Municipal securities 132,603 2,097 354 134,346 Corporate bonds 11,546 63 67 11,542 Certificates of deposits (2) 950 — 3 947 Total debt securities, at fair value $ 404,699 $ 2,270 $ 1,763 $ 405,206 __________________________________________ (1) These categories may include investments issued or guaranteed by government sponsored enterprises such as Fannie Mae ("FNMA"), Freddie Mac ("FHLMC"), Federal Farm Credit Bank ("FFCB"), or one of several Federal Home Loan Banks, as well as, investments guaranteed by Ginnie Mae ("GNMA"), a wholly-owned government entity. (2) Certificates of deposit ("CDs") represent term deposits issued by banks that are subject to FDIC insurance and purchased on the open market.
Schedule of Unrealized Loss on Available-for-Sale Investments	The following tables summarize debt securities having temporary impairment, due to the fair market values having declined below the amortized costs of the individual investments, and the period that the investments have been temporarily impaired at March 31, 2018 and December 31, 2017 . March 31, 2018 Less than 12 months 12 months or longer Total (Dollars in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses # of holdings Federal agency obligations $ 51,385 $ 417 $ — $ — $ 51,385 $ 417 15 Residential federal agency MBS 145,472 3,480 1,983 147 147,455 3,627 41 Commercial federal agency MBS 59,804 1,586 5,050 213 64,854 1,799 16 Municipal securities 84,911 1,382 9,834 560 94,745 1,942 151 Corporate bonds 7,490 170 2,541 106 10,031 276 59 Certificates of deposit 942 8 — — 942 8 4 Total temporarily impaired debt securities $ 350,004 $ 7,043 $ 19,408 $ 1,026 $ 369,412 $ 8,069 286 December 31, 2017 Less than 12 months 12 months or longer Total (Dollars in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses # of holdings Federal agency obligations $ 34,344 $ 82 $ — $ — $ 34,344 $ 82 9 Residential federal agency MBS 109,308 882 2,015 89 111,323 971 30 Commercial federal agency MBS 35,859 205 5,190 81 41,049 286 11 Municipal securities 16,983 129 10,210 225 27,193 354 50 Corporate bonds 2,802 23 2,913 44 5,715 67 33 Certificates of deposit 947 3 — — 947 3 4 Total temporarily impaired debt securities $ 200,243 $ 1,324 $ 20,328 $ 439 $ 220,571 $ 1,763 137
Available-for-Sale Investments Classified by Contractual Maturity Date	The contractual maturity distribution at March 31, 2018 of total debt securities was as follows: (Dollars in thousands) Amortized Cost Fair Value Due in one year or less $ 19,471 $ 19,491 Due after one, but within five years 81,704 80,955 Due after five, but within ten years 134,234 131,440 Due after ten years 184,367 180,327 Total debt securities $ 419,776 $ 412,213
Schedule of Realized Gain (Loss) on Sales of Available-for-Sale Investments	Sales of investments in debt securities, including pending trades based on trade date, if applicable, for the three months ended March 31, 2018 and March 31, 2017 are summarized as follows: Three months ended March 31, (Dollars in thousands) 2018 2017 Amortized cost of debt securities sold (1) $ 668 $ 2,262 Gross realized gains on sales 3 32 Gross realized losses on sales (2 ) — Total proceeds from sales of debt securities $ 669 $ 2,294 _________________________________________ (1) Amortized cost of investments sold is determined on a specific identification basis.

Loans (Tables)

Loans (Tables)	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Schedule of Loans by Loan Classification	Major classifications of loans at the periods indicated were as follows: (Dollars in thousands) March 31, December 31, Commercial real estate $ 1,254,705 $ 1,201,351 Commercial and industrial 503,657 498,802 Commercial construction 228,797 274,905 Total commercial loans 1,987,159 1,975,058 Residential mortgages 198,756 195,492 Home equity loans and lines 96,531 91,706 Consumer 10,149 10,293 Total retail loans 305,436 297,491 Gross loans 2,292,595 2,272,549 Deferred loan origination fees, net (2,422 ) (2,645 ) Total loans 2,290,173 2,269,904 Allowance for loan losses (34,524 ) (32,915 ) Net loans $ 2,255,649 $ 2,236,989
Schedule of Loans Pledged as Collateral	Loans designated as qualified collateral and pledged to the FHLB for borrowing capacity for the periods indicated are summarized below: (Dollars in thousands) March 31, December 31, Commercial real estate $ 216,078 $ 224,703 Residential mortgages 188,758 187,524 Home equity 8,802 9,405 Total loans pledged to FHLB $ 413,638 $ 421,632

Allowance For Loan Loss (Tables

Allowance For Loan Loss (Tables)	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Financing Receivables by Evaluation Method	The balances of loans as of March 31, 2018 by portfolio classification and evaluation method are summarized as follows: (Dollars in thousands) Loans individually evaluated for impairment Loans collectively evaluated for impairment Gross Loans Commercial real estate $ 13,686 $ 1,241,019 $ 1,254,705 Commercial and industrial 11,148 492,509 503,657 Commercial construction 1,670 227,127 228,797 Residential mortgages 715 198,041 198,756 Home equity loans and lines 505 96,026 96,531 Consumer 23 10,126 10,149 Total gross loans $ 27,747 $ 2,264,848 $ 2,292,595 The balances of loans as of December 31, 2017 by portfolio classification and evaluation method are summarized as follows: (Dollars in thousands) Loans individually evaluated for impairment Loans collectively evaluated for impairment Gross Loans Commercial real estate $ 13,739 $ 1,187,612 $ 1,201,351 Commercial and industrial 10,096 488,706 498,802 Commercial construction 1,624 273,281 274,905 Residential mortgages 397 195,095 195,492 Home equity loans and lines 371 91,335 91,706 Consumer 35 10,258 10,293 Total gross loans $ 26,262 $ 2,246,287 $ 2,272,549
Financing Receivable Credit Quality Indicators	The following tables present the Company's credit risk profile for each portfolio classification by internally assigned adverse risk rating category as of the periods indicated. March 31, 2018 Adversely Classified Not Adversely (Dollars in thousands) Substandard Doubtful Loss Classified Gross Loans Commercial real estate $ 13,117 $ — $ — $ 1,241,588 $ 1,254,705 Commercial and industrial 10,137 46 1 493,473 503,657 Commercial construction 1,670 — — 227,127 228,797 Residential mortgages 1,663 — — 197,093 198,756 Home equity loans and lines 555 — — 95,976 96,531 Consumer 40 9 — 10,100 10,149 Total gross loans $ 27,182 $ 55 $ 1 $ 2,265,357 $ 2,292,595 December 31, 2017 Adversely Classified Not Adversely (Dollars in thousands) Substandard Doubtful Loss Classified Gross Loans Commercial real estate $ 12,895 $ — $ — $ 1,188,456 $ 1,201,351 Commercial and industrial 9,915 48 1 488,838 498,802 Commercial construction 1,624 — — 273,281 274,905 Residential mortgages 1,355 — — 194,137 195,492 Home equity loans and lines 513 — — 91,193 91,706 Consumer 52 10 — 10,231 10,293 Total gross loans $ 26,354 $ 58 $ 1 $ 2,246,136 $ 2,272,549
Past Due Financing Receivables	The following tables present an age analysis of past due loans by portfolio classification as of the dates indicated: Balance at March 31, 2018 (Dollars in thousands) 30-59 Days Past Due 60-89 Days Past Due Past Due 90 days or more Total Past Due Loans Current Loans Gross Loans Non-accrual Loans Commercial real estate $ 6,405 $ 1,428 $ 3,574 $ 11,407 $ 1,243,298 $ 1,254,705 $ 6,485 Commercial and industrial 969 894 1,458 3,321 500,336 503,657 2,771 Commercial construction 234 — — 234 228,563 228,797 192 Residential mortgages 1,209 92 88 1,389 197,367 198,756 582 Home equity loans and lines 189 126 131 446 96,085 96,531 505 Consumer 49 10 — 59 10,090 10,149 23 Total gross loans $ 9,055 $ 2,550 $ 5,251 $ 16,856 $ 2,275,739 $ 2,292,595 $ 10,558 Balance at December 31, 2017 (Dollars in thousands) 30-59 Days Past Due 60-89 Days Past Due Past Due 90 days or more Total Past Due Loans Current Loans Gross Loans Non-accrual Loans Commercial real estate $ 4,200 $ 69 $ 3,569 $ 7,838 $ 1,193,513 $ 1,201,351 $ 6,751 Commercial and industrial 374 527 327 1,228 497,574 498,802 1,294 Commercial construction 2,526 518 — 3,044 271,861 274,905 193 Residential mortgages 1,931 93 89 2,113 193,379 195,492 262 Home equity loans and lines 491 120 12 623 91,083 91,706 463 Consumer 51 5 45 101 10,192 10,293 69 Total gross loans $ 9,573 $ 1,332 $ 4,042 $ 14,947 $ 2,257,602 $ 2,272,549 $ 9,032
Impaired Financing Receivables	The following tables set forth the recorded investment in impaired loans and the related specific allowance allocated by portfolio classification as of the dates indicated: Balance at March 31, 2018 (Dollars in thousands) Unpaid contractual principal balance Total recorded investment in impaired loans Recorded investment with no allowance Recorded investment with allowance Related specific allowance Commercial real estate $ 14,994 $ 13,686 $ 13,159 $ 527 $ 52 Commercial and industrial 11,550 11,148 6,530 4,618 2,776 Commercial construction 1,726 1,670 1,670 — — Residential mortgages 835 715 581 134 4 Home equity loans and lines 714 505 505 — — Consumer 23 23 — 23 22 Total $ 29,842 $ 27,747 $ 22,445 $ 5,302 $ 2,854 Balance at December 31, 2017 (Dollars in thousands) Unpaid contractual principal balance Total recorded investment in impaired loans Recorded investment with no allowance Recorded investment with allowance Related specific allowance Commercial real estate $ 15,132 $ 13,739 $ 12,850 $ 889 $ 59 Commercial and industrial 10,458 10,096 7,053 3,043 1,284 Commercial construction 1,678 1,624 1,624 — — Residential mortgages 511 397 262 135 5 Home equity loans and lines 543 371 371 — — Consumer 36 35 — 35 35 Total $ 28,358 $ 26,262 $ 22,160 $ 4,102 $ 1,383 The following table presents the average recorded investment in impaired loans by portfolio classification and the related interest recognized during the periods indicated: Three Months Ended March 31, 2018 Three Months Ended March 31, 2017 (Dollars in thousands) Average recorded investment Interest income (loss) recognized Average recorded investment Interest income (loss) recognized Commercial real estate $ 13,715 $ 94 $ 13,378 $ 101 Commercial and industrial 10,647 77 12,878 105 Commercial construction 1,636 22 2,412 27 Residential mortgages 614 (1 ) 287 — Home equity loans and lines 475 — 539 (2 ) Consumer 32 — 13 — Total $ 27,119 $ 192 $ 29,507 $ 231
Troubled Debt Restructurings on Financing Receivables	Payment defaults by portfolio classification, during the three month period ended March 31, 2017 on loans modified as TDRs within the preceding twelve months are detailed below. Three months ended March 31, 2017 (Dollars in thousands) Number of TDRs that defaulted Post- modification outstanding recorded investment Commercial real estate 3 $ 956 Commercial and industrial 1 231 Commercial construction — — Residential mortgages — — Home equity loans and lines — — Consumer — — Total 4 $ 1,187 The following table sets forth the post modification balances of TDRs listed by type of modification for TDRs that occurred during the periods indicated. Three months ended March 31, 2018 March 31, 2017 (Dollars in thousands) Number of restructurings Amount Number of restructurings Amount Extended maturity date — — 2 3,063 Temporary payment reduction and payment re-amortization of remaining principal over extended term 2 139 1 374 Temporary interest only payment plan 2 132 1 94 Total 4 $ 271 4 $ 3,531 Amount of specific reserves included in the allowance for loan losses associated with TDRs listed above $ 120 $ — Loans modified as TDRs during the three month periods ended March 31, 2018 and March 31, 2017 by portfolio classification are detailed below. Three months ended March 31, 2018 March 31, 2017 (Dollars in thousands) Number of restructurings Pre-modification outstanding recorded investment Post-modification outstanding recorded investment Number of restructurings Pre-modification outstanding recorded investment Post-modification outstanding recorded investment Commercial real estate 2 $ 131 $ 132 1 $ 375 $ 374 Commercial and industrial 2 142 139 2 2,952 2,952 Commercial construction — — — 1 206 205 Residential mortgages — — — — — — Home equity loans and lines — — — — — — Consumer — — — — — — Total 4 $ 273 $ 271 4 $ 3,533 $ 3,531
Allowance for Credit Losses on Financing Receivables	Changes in the allowance for loan losses by portfolio classification for the three months ended March 31, 2018 are presented below: (Dollars in thousands) Cmml Real Estate Cmml and Industrial Cmml Constr Resid. Mortgage Home Equity Consumer Total Beginning Balance at December 31, 2017 $ 17,545 $ 9,669 $ 3,947 $ 904 $ 608 $ 242 $ 32,915 Provision 755 1,435 (664 ) 10 20 44 1,600 Recoveries — 108 — — 1 5 114 Less: Charge offs — 41 — — — 64 105 Ending Balance at March 31, 2018 $ 18,300 $ 11,171 $ 3,283 $ 914 $ 629 $ 227 $ 34,524 Ending allowance balance: Allocated to loans individually evaluated for impairment $ 52 $ 2,776 $ — $ 4 $ — $ 22 $ 2,854 Allocated to loans collectively evaluated for impairment $ 18,248 $ 8,395 $ 3,283 $ 910 $ 629 $ 205 $ 31,670 Changes in the allowance for loan losses by portfolio classification for the three months ended March 31, 2017 are presented below: (Dollars in thousands) Cmml Real Estate Cmml and Industrial Cmml Constr Resid. Mortgage Home Equity Consumer Total Beginning Balance at December 31, 2016 $ 14,902 $ 11,204 $ 3,406 $ 960 $ 634 $ 236 $ 31,342 Provision 316 (195 ) (42 ) 18 — 28 125 Recoveries 76 272 — — 1 3 352 Less: Charge offs — 103 — — — 33 136 Ending Balance at March 31, 2017 $ 15,294 $ 11,178 $ 3,364 $ 978 $ 635 $ 234 $ 31,683 Ending allowance balance: Allocated to loans individually evaluated for impairment $ 409 $ 1,928 $ 23 $ — $ — $ 14 $ 2,374 Allocated to loans collectively evaluated for impairment $ 14,885 $ 9,250 $ 3,341 $ 978 $ 635 $ 220 $ 29,309

Deposits (Tables)

Deposits (Tables)	3 Months Ended
	Mar. 31, 2018
Deposits [Abstract]
Schedule of Deposit Liabilities	Deposits are summarized as follows: (Dollars in thousands) March 31, 2018 December 31, 2017 Non-interest bearing demand deposits $ 717,656 $ 705,846 Interest-bearing checking 382,580 391,111 Savings 193,766 193,385 Money market 868,359 807,931 Certificates of deposit $250,000 or less 173,720 150,445 Certificates of deposit more than $250,000 49,814 45,154 Total customer deposits 2,385,895 2,293,872 Brokered deposits (1) 185,494 147,490 Total deposits $ 2,571,389 $ 2,441,362 ___________________________________ (1) Brokered CDs $250,000 and under.

Derivatives and Hedging Activ27

Derivatives and Hedging Activities (Tables)	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivatives, Fair Value and Classification	The table below presents the fair value and classification of the Company’s derivative financial instruments for the periods presented: As of March 31, 2018 As of December 31, 2017 (Dollars in thousands) Asset Derivatives Liability Derivatives Asset Derivatives Liability Derivatives Interest rate contracts - pay floating, received fixed $ — $ 887 $ 25 $ 568 Interest rate contracts - pay fixed, receive floating 887 — 543 — Total interest rate swaps $ 887 $ 887 $ 568 $ 568
Schedule of Derivatives- Offsetting Assets and Liabilities	The table below presents the Company's asset derivative positions and the potential effect of those netting arrangements on its financial position, as of the periods presented. Interest rate swaps with customers are not subject to master netting agreements and therefore are not included in the table below. As of March 31, 2018 (Dollars in thousands) Gross Amounts of Recognized Assets Gross Amounts Offset in the Statement of Financial Position Net Amounts of Assets Presented in the Statement of Financial Position Asset Derivatives Interest rate contracts - pay fixed, receive floating $ 887 $ — $ 887 As of December 31, 2017 (Dollars in thousands) Gross Amounts of Recognized Assets Gross Amounts Offset in the Statement of Financial Position Net Amounts of Assets Presented in the Statement of Financial Position Asset Derivatives Interest rate contracts - pay fixed, receive floating $ 568 $ 25 $ 543

Supplemental Life Insurance (Ta

Supplemental Life Insurance (Tables)	3 Months Ended
	Mar. 31, 2018
Supplemental Life Insurance
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Schedule of Net Benefit Costs	The following table illustrates the net periodic post-retirement benefit cost for the supplemental life insurance plans for the periods indicated: Three months ended March 31, (Dollars in thousands) 2018 2017 Service Cost $ (17 ) $ (3 ) Interest Cost 62 23 Net periodic benefit cost $ 45 $ 20

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	The table below provides a summary of the options granted, including the fair value as a percentage of the market value of the stock at the date of grant and the average assumptions used during the periods indicated: Three Months Ended March 31, 2018 2017 Options granted 14,755 15,009 Term in years 10 10 Weighted average assumptions used in the fair value model: Expected volatility 37 % 40 % Expected dividend yield 2.10 % 2.09 % Expected life in years 6.5 7 Risk-free interest rate 2.86 % 2.35 % Weighted average market price on date of grants $ 34.33 $ 30.46 Per share weighted average fair value $ 11.98 $ 11.34 Fair value as a percentage of market value at grant date 35 % 37 %
Schedule of Restricted Stock Awards Granted	The table below provides a summary of restricted stock awards granted during the periods indicated: Three Months Ended March 31, Restricted Stock Awards (no. of underlying shares) 2018 2017 Two year vesting 7,280 6,944 Four year vesting 16,666 16,253 Performance-based vesting 20,559 25,623 Total restricted stock awards 44,505 48,820 Weighted average grant date fair value $ 34.33 $ 30.46

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Schedule of Weighted Average Number of Shares	The table below presents the increase in average shares outstanding, using the treasury stock method, for the diluted earnings per share calculation for the periods indicated: Three months ended March 31, 2018 2017 Basic weighted average common shares outstanding 11,628,587 11,508,811 Dilutive shares 72,267 90,051 Diluted weighted average common shares outstanding 11,700,854 11,598,862

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value, Assets Measured on Recurring and Nonrecurring Basis	The following tables summarize significant assets and liabilities carried at fair value and placement in the fair value hierarchy at the dates specified: March 31, 2018 Fair Value Measurements using: (Dollars in thousands) Fair Value (Level 1) (Level 2) (Level 3) Assets measured on a recurring basis: Debt securities $ 412,213 $ — $ 412,213 $ — Equity securities 295 295 — — FHLB stock 2,370 — — 2,370 Interest rate swaps 887 — 887 — Assets measured on a non-recurring basis: Impaired loans (collateral dependent) 2,424 — — 2,424 Liabilities measured on a recurring basis: Interest rate swaps $ 887 $ — $ 887 $ — December 31, 2017 Fair Value Measurements using: (Dollars in thousands) Fair Value (Level 1) (Level 2) (Level 3) Assets measured on a recurring basis: Debt securities $ 405,206 $ — $ 405,206 $ — FHLB stock 5,215 — — 5,215 Interest rate swaps 568 — 568 — Assets measured on a non-recurring basis: Impaired loans (collateral dependent) 2,696 — — 2,696 Liabilities measured on a recurring basis: Interest rate swaps $ 568 $ — $ 568 $ —
Quantitative Information About Significant Unobservable Inputs for Fair Value Measurements	The following table presents additional quantitative information about assets measured at fair value on a recurring and non-recurring basis for which the Company utilized Level 3 inputs (significant unobservable inputs for situations in which there is little, if any, market activity for the asset or liability) to determine fair value as of March 31, 2018 : (Dollars in thousands) Fair Value Valuation Technique Unobservable Input Unobservable Input Value or Range Assets measured on a recurring basis: FHLB stock $ 2,370 FHLB Stated Par Value N/A N/A Assets measured on a non-recurring basis: Impaired loans (collateral dependent) $ 2,424 Appraisal of collateral Appraisal adjustments (1) 5% - 50% __________________________________________ (1) Appraisals may be adjusted by management for qualitative factors such as economic conditions and estimated liquidation expenses.
Fair Value, by Balance Sheet Grouping	The carrying values, estimated fair values and placement in the fair value hierarchy of the Company's consolidated financial instruments for which fair value is only disclosed but not recognized on the consolidated balance sheet at the dates indicated are summarized as follows: March 31, 2018 Fair value measurement (Dollars in thousands) Carrying Amount Fair Value Level 1 Inputs Level 2 Inputs Level 3 Inputs Financial assets: Loans, net $ 2,255,649 $ 2,237,319 $ — $ — $ 2,237,319 Financial liabilities: Certificates of deposit (including brokered) 409,028 406,487 — 406,487 — Subordinated debt 14,850 13,949 — — 13,949 December 31, 2017 Fair value measurement (Dollars in thousands) Carrying Amount Fair Value Level 1 Inputs Level 2 Inputs Level 3 Inputs Financial assets: Loans held for sale $ 208 $ 208 $ — $ 208 $ — Loans, net 2,236,989 2,236,169 — — 2,236,169 Financial liabilities: Certificates of deposit (including brokered) 343,089 341,765 — 341,765 — Borrowed funds 89,000 88,996 — 88,996 — Subordinated debt 14,847 14,208 — — 14,208

Summary of Significant Accoun32

Summary of Significant Accounting Policies (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)propertybranchessegment	Dec. 31, 2017USD ($)	Jul. 31, 2000branches
Accounting Policies [Abstract]
Number of branches | branches	24
Reportable operating segments | segment	1
Federal Reserve Bank Average Daily Reserve Requirement included in Cash and Due from Banks | $	$ 9,300
Number of operating leases | property	17
Goodwill | $	$ 5,656	$ 5,656
Number of offices related to the goodwill in acquisition | branches			2

Investment Securities Available

Investment Securities Available-for-Sale (Details) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Debt Securities, Gross Unrealized Gain (Loss) [Abstract]
Available-for-sale Securities, Debt Securities, Fair Value		$ 412,213
Securities pledged as collateral		411,300
Debt securities
Debt Securities, Gross Unrealized Gain (Loss) [Abstract]
AFS-Available-for-sale Securities, Debt Securities, Amortized Cost		419,776	$ 404,699
AFS - Unrealized gains		506	2,270
AFS - Unrealized losses		8,069	1,763
Available-for-sale Securities, Debt Securities, Fair Value		412,213	405,206
Federal agency obligations
Debt Securities, Gross Unrealized Gain (Loss) [Abstract]
AFS-Available-for-sale Securities, Debt Securities, Amortized Cost	[1]	51,802	51,769
AFS - Unrealized gains	[1]	0	30
AFS - Unrealized losses	[1]	417	82
Available-for-sale Securities, Debt Securities, Fair Value	[1]	51,385	51,717
Residential federal agency MBS
Debt Securities, Gross Unrealized Gain (Loss) [Abstract]
AFS-Available-for-sale Securities, Debt Securities, Amortized Cost	[1]	154,739	141,054
AFS - Unrealized gains	[1]	5	71
AFS - Unrealized losses	[1]	3,627	971
Available-for-sale Securities, Debt Securities, Fair Value	[1]	151,117	140,154
Commercial federal agency MBS
Debt Securities, Gross Unrealized Gain (Loss) [Abstract]
AFS-Available-for-sale Securities, Debt Securities, Amortized Cost	[1]	66,653	66,777
AFS - Unrealized gains	[1]	0	9
AFS - Unrealized losses	[1]	1,799	286
Available-for-sale Securities, Debt Securities, Fair Value	[1]	64,854	66,500
Collateralized Mortgage Obligations
Debt Securities, Gross Unrealized Gain (Loss) [Abstract]
Available-for-sale Securities, Debt Securities, Fair Value		183,200	171,700
Municipal securities
Debt Securities, Gross Unrealized Gain (Loss) [Abstract]
AFS-Available-for-sale Securities, Debt Securities, Amortized Cost		134,306	132,603
AFS - Unrealized gains		495	2,097
AFS - Unrealized losses		1,942	354
Available-for-sale Securities, Debt Securities, Fair Value		132,859	134,346
Corporate bonds
Debt Securities, Gross Unrealized Gain (Loss) [Abstract]
AFS-Available-for-sale Securities, Debt Securities, Amortized Cost		11,326	11,546
AFS - Unrealized gains		6	63
AFS - Unrealized losses		276	67
Available-for-sale Securities, Debt Securities, Fair Value		11,056	11,542
Certificates of Deposit
Debt Securities, Gross Unrealized Gain (Loss) [Abstract]
AFS-Available-for-sale Securities, Debt Securities, Amortized Cost	[2]	950	950
AFS - Unrealized gains	[2]	0	0
AFS - Unrealized losses	[2]	8	3
Available-for-sale Securities, Debt Securities, Fair Value	[2]	$ 942	$ 947
[1]	These categories may include investments issued or guaranteed by government sponsored enterprises such as Fannie Mae ("FNMA"), Freddie Mac ("FHLMC"), Federal Farm Credit Bank ("FFCB"), or one of several Federal Home Loan Banks, as well as, investments guaranteed by Ginnie Mae ("GNMA"), a wholly-owned government entity.
[2]	Certificates of deposit ("CDs") represent term deposits issued by banks that are subject to FDIC insurance and purchased on the open market.

Investment Securities Availab34

Investment Securities Available-for-Sale - Continuous Loss Position (Details) $ in Thousands	Mar. 31, 2018USD ($)investments	Dec. 31, 2017USD ($)investments
Schedule of Available-for-sale Securities [Line Items]
AFS investments temporarily impaired, less than 12 months, fair value	$ 350,004	$ 200,243
AFS investments temporarily impaired, less than 12 months, unrealized losses	7,043	1,324
AFS investments temporarily impaired, 12 months or longer, fair value	19,408	20,328
AFS investments temporarily impaired, 12 months or longer, Unrealized Losses	1,026	439
AFS investments Temporarily Impaired, Fair Value	369,412	220,571
AFS investments temporarily impaired unrealized losses	$ 8,069	$ 1,763
AFS number of securities in loss position | investments	286	137
Federal agency obligations
Schedule of Available-for-sale Securities [Line Items]
AFS investments temporarily impaired, less than 12 months, fair value	$ 51,385	$ 34,344
AFS investments temporarily impaired, less than 12 months, unrealized losses	417	82
AFS investments temporarily impaired, 12 months or longer, fair value	0	0
AFS investments temporarily impaired, 12 months or longer, Unrealized Losses	0	0
AFS investments Temporarily Impaired, Fair Value	51,385	34,344
AFS investments temporarily impaired unrealized losses	$ 417	$ 82
AFS number of securities in loss position | investments	15	9
Residential federal agency MBS
Schedule of Available-for-sale Securities [Line Items]
AFS investments temporarily impaired, less than 12 months, fair value	$ 145,472	$ 109,308
AFS investments temporarily impaired, less than 12 months, unrealized losses	3,480	882
AFS investments temporarily impaired, 12 months or longer, fair value	1,983	2,015
AFS investments temporarily impaired, 12 months or longer, Unrealized Losses	147	89
AFS investments Temporarily Impaired, Fair Value	147,455	111,323
AFS investments temporarily impaired unrealized losses	$ 3,627	$ 971
AFS number of securities in loss position | investments	41	30
Commercial federal agency MBS
Schedule of Available-for-sale Securities [Line Items]
AFS investments temporarily impaired, less than 12 months, fair value	$ 59,804	$ 35,859
AFS investments temporarily impaired, less than 12 months, unrealized losses	1,586	205
AFS investments temporarily impaired, 12 months or longer, fair value	5,050	5,190
AFS investments temporarily impaired, 12 months or longer, Unrealized Losses	213	81
AFS investments Temporarily Impaired, Fair Value	64,854	41,049
AFS investments temporarily impaired unrealized losses	$ 1,799	$ 286
AFS number of securities in loss position | investments	16	11
Municipal securities
Schedule of Available-for-sale Securities [Line Items]
AFS investments temporarily impaired, less than 12 months, fair value	$ 84,911	$ 16,983
AFS investments temporarily impaired, less than 12 months, unrealized losses	1,382	129
AFS investments temporarily impaired, 12 months or longer, fair value	9,834	10,210
AFS investments temporarily impaired, 12 months or longer, Unrealized Losses	560	225
AFS investments Temporarily Impaired, Fair Value	94,745	27,193
AFS investments temporarily impaired unrealized losses	$ 1,942	$ 354
AFS number of securities in loss position | investments	151	50
Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
AFS investments temporarily impaired, less than 12 months, fair value	$ 7,490	$ 2,802
AFS investments temporarily impaired, less than 12 months, unrealized losses	170	23
AFS investments temporarily impaired, 12 months or longer, fair value	2,541	2,913
AFS investments temporarily impaired, 12 months or longer, Unrealized Losses	106	44
AFS investments Temporarily Impaired, Fair Value	10,031	5,715
AFS investments temporarily impaired unrealized losses	$ 276	$ 67
AFS number of securities in loss position | investments	59	33
Certificates of Deposit
Schedule of Available-for-sale Securities [Line Items]
AFS investments temporarily impaired, less than 12 months, fair value	$ 942	$ 947
AFS investments temporarily impaired, less than 12 months, unrealized losses	8	3
AFS investments temporarily impaired, 12 months or longer, fair value	0	0
AFS investments temporarily impaired, 12 months or longer, Unrealized Losses	0	0
AFS investments Temporarily Impaired, Fair Value	942	947
AFS investments temporarily impaired unrealized losses	$ 8	$ 3
AFS number of securities in loss position | investments	4	4

Investment Securities Availab35

Investment Securities Available-for-Sale -Maturities (Details) $ in Thousands	Mar. 31, 2018USD ($)
Investments, Debt and Equity Securities [Abstract]
AFS-Amortized Cost, Within One Year	$ 19,471
AFS-Fair Value, Within One Year	19,491
AFS-Amortized Cost Basis, After One, But Within Five Years	81,704
AFS-Fair Value, After One, But Within Five Years	80,955
AFS-Amortized Cost, After Five, But Within Ten Years	134,234
AFS-Fair Value, after Five but Within Ten Years	131,440
AFS-Amortized Cost Basis, After Ten Years	184,367
AFS-Fair Value, After Ten Years	180,327
Available-for-sale Debt Securities, Amortized Cost	419,776
Available-for-sale Securities, Debt Securities, Fair Value	412,213
Callable debt securities, fair value	$ 76,500

Investment Securities Availab36

Investment Securities Available-for-Sale -Sales (Details) - Debt securities - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Amortized cost of debt securities sold, including pending trades based on trade date	[1]	$ 668	$ 2,262
Debt Securities, Gross realized gains on sales		3	32
Debt Securities, Gross realized losses on sales		(2)	0
Proceeds from sale of debt securities, including pending trades based on trade date		$ 669	$ 2,294
[1]	Amortized cost of investments sold is determined on a specific identification basis.

Investment Securities Equity Se

Investment Securities Equity Securities (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Schedule of Marketable Securities [Line Items]
Equity securities at fair value after adoption of ASU 2016-01	$ 295,000
Investment securities at fair value	412,508,000		$ 405,206,000
Equity investments
Schedule of Marketable Securities [Line Items]
Investment securities at fair value			$ 0
Amortized cost of equity securities sold, including pending trades after adoption of ASU 2016-01	$ 0
Available-for-sale Securities, Amortized Cost Basis, Investments Sold, Including Pending Trades		$ 6,900,000
Net gains on equities before the adoption of ASU 2016-01		$ 508,000

Loans - Balance by Class of Loa

Loans - Balance by Class of Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Schedule of Loans by Loan Classification [Line Items]
Gross loans	$ 2,292,595	$ 2,272,549
Deferred loan origination fees, net	(2,422)	(2,645)
Total loans	2,290,173	2,269,904
Allowance for loan losses	(34,524)	(32,915)	$ (31,683)	$ (31,342)
Net Loans	2,255,649	2,236,989
Commercial
Schedule of Loans by Loan Classification [Line Items]
Gross loans	1,987,159	1,975,058
Commercial real estate
Schedule of Loans by Loan Classification [Line Items]
Gross loans	1,254,705	1,201,351
Allowance for loan losses	(18,300)	(17,545)	(15,294)	(14,902)
Commercial and industrial
Schedule of Loans by Loan Classification [Line Items]
Gross loans	503,657	498,802
Allowance for loan losses	(11,171)	(9,669)	(11,178)	(11,204)
Commercial construction
Schedule of Loans by Loan Classification [Line Items]
Gross loans	228,797	274,905
Allowance for loan losses	(3,283)	(3,947)	(3,364)	(3,406)
Retail
Schedule of Loans by Loan Classification [Line Items]
Gross loans	305,436	297,491
Residential
Schedule of Loans by Loan Classification [Line Items]
Gross loans	198,756	195,492
Allowance for loan losses	(914)	(904)	(978)	(960)
Home Equity
Schedule of Loans by Loan Classification [Line Items]
Gross loans	96,531	91,706
Allowance for loan losses	(629)	(608)	(635)	(634)
Consumer
Schedule of Loans by Loan Classification [Line Items]
Gross loans	10,149	10,293
Allowance for loan losses	$ (227)	$ (242)	$ (234)	$ (236)

Loans - Loan Categories Narrati

Loans - Loan Categories Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018USD ($)payment	Dec. 31, 2017USD ($)
Commercial
Schedule of Loans by Loan Classification [Line Items]
Participation loans amount	$ 90.6	$ 91.6
Participations loans sold that are still serviced amount	$ 70.8	70.7
Commercial real estate | Minimum
Schedule of Loans by Loan Classification [Line Items]
Repayment period, term of loan	15 years
Commercial real estate | Maximum
Schedule of Loans by Loan Classification [Line Items]
Repayment period, term of loan	25 years
Commercial and industrial | Minimum
Schedule of Loans by Loan Classification [Line Items]
Repayment period, term of loan	1 year
Commercial and industrial | Maximum
Schedule of Loans by Loan Classification [Line Items]
Repayment period, term of loan	7 years
Commercial construction | Minimum
Schedule of Loans by Loan Classification [Line Items]
Repayment period, term of loan	1 year
Commercial construction | Maximum
Schedule of Loans by Loan Classification [Line Items]
Repayment period, term of loan	3 years
Residential
Schedule of Loans by Loan Classification [Line Items]
Early Payment Default Period | payment	4
Amount of loans serviced for others	$ 18	$ 18.4
Residential | Maximum
Schedule of Loans by Loan Classification [Line Items]
Repayment period, term of loan	30 years
Home Equity | Maximum
Schedule of Loans by Loan Classification [Line Items]
Loan-to-value ratio	80.00%
Home Equity Loans | Minimum
Schedule of Loans by Loan Classification [Line Items]
Repayment period, term of loan	3 years
Home Equity Loans | Maximum
Schedule of Loans by Loan Classification [Line Items]
Repayment period, term of loan	15 years
Home equity lines of credit
Schedule of Loans by Loan Classification [Line Items]
Term of interest only payments	10 years
Term of Principal and Interest Payments after Interest only term	15 years
Multi-family owner occupied residential property | Minimum
Schedule of Loans by Loan Classification [Line Items]
Loan-to-value ratio	75.00%
Single family owner occupied residential property | Maximum
Schedule of Loans by Loan Classification [Line Items]
Loan-to-value ratio	97.00%

Loans - Loans Serving as Collat

Loans - Loans Serving as Collateral (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financial Instruments Owned and Pledged as Collateral [Line Items]
Loans pledged to the FHLB for borrowing capacity	$ 413,638	$ 421,632
Commercial real estate
Financial Instruments Owned and Pledged as Collateral [Line Items]
Loans pledged to the FHLB for borrowing capacity	216,078	224,703
Residential
Financial Instruments Owned and Pledged as Collateral [Line Items]
Loans pledged to the FHLB for borrowing capacity	188,758	187,524
Home Equity
Financial Instruments Owned and Pledged as Collateral [Line Items]
Loans pledged to the FHLB for borrowing capacity	$ 8,802	$ 9,405

Allowance For Loan Loss - Evalu

Allowance For Loan Loss - Evaluation Method (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Financing Receivable by Evaluation Method [Line Items]
Loans individually evaluated for impairment	$ 27,747	$ 26,262
Loans collectively evaluated for impairment	2,264,848	2,246,287
Gross loans	2,292,595	2,272,549
Commercial real estate
Schedule of Financing Receivable by Evaluation Method [Line Items]
Loans individually evaluated for impairment	13,686	13,739
Loans collectively evaluated for impairment	1,241,019	1,187,612
Gross loans	1,254,705	1,201,351
Commercial and industrial
Schedule of Financing Receivable by Evaluation Method [Line Items]
Loans individually evaluated for impairment	11,148	10,096
Loans collectively evaluated for impairment	492,509	488,706
Gross loans	503,657	498,802
Commercial construction
Schedule of Financing Receivable by Evaluation Method [Line Items]
Loans individually evaluated for impairment	1,670	1,624
Loans collectively evaluated for impairment	227,127	273,281
Gross loans	228,797	274,905
Residential
Schedule of Financing Receivable by Evaluation Method [Line Items]
Loans individually evaluated for impairment	715	397
Loans collectively evaluated for impairment	198,041	195,095
Gross loans	198,756	195,492
Home Equity
Schedule of Financing Receivable by Evaluation Method [Line Items]
Loans individually evaluated for impairment	505	371
Loans collectively evaluated for impairment	96,026	91,335
Gross loans	96,531	91,706
Consumer
Schedule of Financing Receivable by Evaluation Method [Line Items]
Loans individually evaluated for impairment	23	35
Loans collectively evaluated for impairment	10,126	10,258
Gross loans	$ 10,149	$ 10,293

Allowance For Loan Loss - Adver

Allowance For Loan Loss - Adversely Classified Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Gross loans	$ 2,292,595	$ 2,272,549
Adversely classified loans to total loans	1.19%	1.16%
Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Gross loans	$ 1,254,705	$ 1,201,351
Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Gross loans	503,657	498,802
Commercial construction
Financing Receivable, Recorded Investment [Line Items]
Gross loans	228,797	274,905
Residential
Financing Receivable, Recorded Investment [Line Items]
Gross loans	198,756	195,492
Home Equity
Financing Receivable, Recorded Investment [Line Items]
Gross loans	96,531	91,706
Consumer
Financing Receivable, Recorded Investment [Line Items]
Gross loans	10,149	10,293
Substandard
Financing Receivable, Recorded Investment [Line Items]
Gross loans	27,182	26,354
Substandard | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Gross loans	13,117	12,895
Substandard | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Gross loans	10,137	9,915
Substandard | Commercial construction
Financing Receivable, Recorded Investment [Line Items]
Gross loans	1,670	1,624
Substandard | Residential
Financing Receivable, Recorded Investment [Line Items]
Gross loans	1,663	1,355
Substandard | Home Equity
Financing Receivable, Recorded Investment [Line Items]
Gross loans	555	513
Substandard | Consumer
Financing Receivable, Recorded Investment [Line Items]
Gross loans	40	52
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Gross loans	55	58
Doubtful | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Gross loans	0	0
Doubtful | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Gross loans	46	48
Doubtful | Commercial construction
Financing Receivable, Recorded Investment [Line Items]
Gross loans	0	0
Doubtful | Residential
Financing Receivable, Recorded Investment [Line Items]
Gross loans	0	0
Doubtful | Home Equity
Financing Receivable, Recorded Investment [Line Items]
Gross loans	0	0
Doubtful | Consumer
Financing Receivable, Recorded Investment [Line Items]
Gross loans	9	10
Loss
Financing Receivable, Recorded Investment [Line Items]
Gross loans	1	1
Loss | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Gross loans	0	0
Loss | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Gross loans	1	1
Loss | Commercial construction
Financing Receivable, Recorded Investment [Line Items]
Gross loans	0	0
Loss | Residential
Financing Receivable, Recorded Investment [Line Items]
Gross loans	0	0
Loss | Home Equity
Financing Receivable, Recorded Investment [Line Items]
Gross loans	0	0
Loss | Consumer
Financing Receivable, Recorded Investment [Line Items]
Gross loans	0	0
Not Adversely Classified
Financing Receivable, Recorded Investment [Line Items]
Gross loans	2,265,357	2,246,136
Not Adversely Classified | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Gross loans	1,241,588	1,188,456
Not Adversely Classified | Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Gross loans	493,473	488,838
Not Adversely Classified | Commercial construction
Financing Receivable, Recorded Investment [Line Items]
Gross loans	227,127	273,281
Not Adversely Classified | Residential
Financing Receivable, Recorded Investment [Line Items]
Gross loans	197,093	194,137
Not Adversely Classified | Home Equity
Financing Receivable, Recorded Investment [Line Items]
Gross loans	95,976	91,193
Not Adversely Classified | Consumer
Financing Receivable, Recorded Investment [Line Items]
Gross loans	$ 10,100	$ 10,231

Allowance For Loan Loss - Past

Allowance For Loan Loss - Past Due and Non-Accrual Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	$ 2,292,595	$ 2,272,549
Total Past Due Loans	16,856	14,947
Current Loans	2,275,739	2,257,602
Non-accrual loans	$ 10,558	$ 9,032
The ratio of non-accrual loans to total loans	0.46%	0.40%
Commercial real estate
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	$ 1,254,705	$ 1,201,351
Total Past Due Loans	11,407	7,838
Current Loans	1,243,298	1,193,513
Non-accrual loans	6,485	6,751
Commercial and industrial
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	503,657	498,802
Total Past Due Loans	3,321	1,228
Current Loans	500,336	497,574
Non-accrual loans	2,771	1,294
Commercial construction
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	228,797	274,905
Total Past Due Loans	234	3,044
Current Loans	228,563	271,861
Non-accrual loans	192	193
Residential
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	198,756	195,492
Total Past Due Loans	1,389	2,113
Current Loans	197,367	193,379
Non-accrual loans	582	262
Home Equity
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	96,531	91,706
Total Past Due Loans	446	623
Current Loans	96,085	91,083
Non-accrual loans	505	463
Consumer
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	10,149	10,293
Total Past Due Loans	59	101
Current Loans	10,090	10,192
Non-accrual loans	23	69
Loans 30 to 59 Days Past Due
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	9,055	9,573
Loans 30 to 59 Days Past Due | Commercial real estate
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	6,405	4,200
Loans 30 to 59 Days Past Due | Commercial and industrial
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	969	374
Loans 30 to 59 Days Past Due | Commercial construction
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	234	2,526
Loans 30 to 59 Days Past Due | Residential
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	1,209	1,931
Loans 30 to 59 Days Past Due | Home Equity
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	189	491
Loans 30 to 59 Days Past Due | Consumer
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	49	51
Loans 60 to 89 Days Past Due
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	2,550	1,332
Loans 60 to 89 Days Past Due | Commercial real estate
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	1,428	69
Loans 60 to 89 Days Past Due | Commercial and industrial
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	894	527
Loans 60 to 89 Days Past Due | Commercial construction
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	0	518
Loans 60 to 89 Days Past Due | Residential
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	92	93
Loans 60 to 89 Days Past Due | Home Equity
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	126	120
Loans 60 to 89 Days Past Due | Consumer
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	10	5
Loans Equal to Greater than 90 Days Past Due
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	5,251	4,042
Loans Equal to Greater than 90 Days Past Due | Commercial real estate
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	3,574	3,569
Loans Equal to Greater than 90 Days Past Due | Commercial and industrial
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	1,458	327
Loans Equal to Greater than 90 Days Past Due | Commercial construction
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	0	0
Loans Equal to Greater than 90 Days Past Due | Residential
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	88	89
Loans Equal to Greater than 90 Days Past Due | Home Equity
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	131	12
Loans Equal to Greater than 90 Days Past Due | Consumer
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	0	45
Not Adversely Classified
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	2,265,357	2,246,136
Non-accrual loans not adversely classified	224	21
Not Adversely Classified | Commercial real estate
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	1,241,588	1,188,456
Not Adversely Classified | Commercial and industrial
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	493,473	488,838
Not Adversely Classified | Commercial construction
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	227,127	273,281
Not Adversely Classified | Residential
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	197,093	194,137
Not Adversely Classified | Home Equity
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	95,976	91,193
Not Adversely Classified | Consumer
Schedule of Aging of Financing Receivables [Line Items]
Gross loans	$ 10,100	$ 10,231

Allowance For Loan Loss - Impai

Allowance For Loan Loss - Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Total recorded investment in impaired loans	$ 27,747		$ 26,262
Total accruing impaired loans	17,200		17,400
Impaired non-accrual loans	10,600		8,900
Unpaid contractual principal balance	29,842		28,358
Recorded investment with no allowance	22,445		22,160
Recorded investment with allowance	5,302		4,102
Related allowance	2,854		1,383
Average recorded investment	27,119	$ 29,507
Interest income recognized	192	231
Commercial real estate
Financing Receivable, Impaired [Line Items]
Total recorded investment in impaired loans	13,686		13,739
Unpaid contractual principal balance	14,994		15,132
Recorded investment with no allowance	13,159		12,850
Recorded investment with allowance	527		889
Related allowance	52		59
Average recorded investment	13,715	13,378
Interest income recognized	94	101
Commercial and industrial
Financing Receivable, Impaired [Line Items]
Total recorded investment in impaired loans	11,148		10,096
Unpaid contractual principal balance	11,550		10,458
Recorded investment with no allowance	6,530		7,053
Recorded investment with allowance	4,618		3,043
Related allowance	2,776		1,284
Average recorded investment	10,647	12,878
Interest income recognized	77	105
Commercial construction
Financing Receivable, Impaired [Line Items]
Total recorded investment in impaired loans	1,670		1,624
Unpaid contractual principal balance	1,726		1,678
Recorded investment with no allowance	1,670		1,624
Recorded investment with allowance	0		0
Related allowance	0		0
Average recorded investment	1,636	2,412
Interest income recognized	22	27
Residential
Financing Receivable, Impaired [Line Items]
Total recorded investment in impaired loans	715		397
Unpaid contractual principal balance	835		511
Recorded investment with no allowance	581		262
Recorded investment with allowance	134		135
Related allowance	4		5
Average recorded investment	614	287
Interest income recognized	(1)	0
Home Equity
Financing Receivable, Impaired [Line Items]
Total recorded investment in impaired loans	505		371
Unpaid contractual principal balance	714		543
Recorded investment with no allowance	505		371
Recorded investment with allowance	0		0
Related allowance	0		0
Average recorded investment	475	539
Interest income recognized	0	(2)
Consumer
Financing Receivable, Impaired [Line Items]
Total recorded investment in impaired loans	23		35
Unpaid contractual principal balance	23		36
Recorded investment with no allowance	0		0
Recorded investment with allowance	23		35
Related allowance	22		$ 35
Average recorded investment	32	13
Interest income recognized	$ 0	$ 0

Allowance For Loan Loss - Troub

Allowance For Loan Loss - Troubled Debt Restructures (Details)	3 Months Ended
	Mar. 31, 2018USD ($)restructuring	Mar. 31, 2017USD ($)restructuring	Dec. 31, 2017USD ($)
Financing Receivable, Modifications [Line Items]
Total Troubled Debt Restructure (TDR) loans	$ 20,600,000		$ 20,300,000
TDR loans on accrual status	17,200,000		17,400,000
TDR loans included in non-performing loans	$ 3,400,000		$ 2,900,000
Number of restructurings | restructuring	4	4
Post-modification outstanding recorded investment	$ 271,000	$ 3,531,000
Specific reserves allocated to TDRs	120,000	0
Pre-modification outstanding recorded investment	$ 273,000	$ 3,533,000
Number of TDRs that defaulted | restructuring	0	4
Post-modification outstanding recorded investment, TDRs that defaulted		$ 1,187,000
Charge-offs associated with new TDRs	$ 0	$ 0
Commercial real estate
Financing Receivable, Modifications [Line Items]
Number of restructurings | restructuring	2	1
Post-modification outstanding recorded investment	$ 132,000	$ 374,000
Pre-modification outstanding recorded investment	$ 131,000	$ 375,000
Number of TDRs that defaulted | restructuring		3
Post-modification outstanding recorded investment, TDRs that defaulted		$ 956,000
Commercial and industrial
Financing Receivable, Modifications [Line Items]
Number of restructurings | restructuring	2	2
Post-modification outstanding recorded investment	$ 139,000	$ 2,952,000
Pre-modification outstanding recorded investment	$ 142,000	$ 2,952,000
Number of TDRs that defaulted | restructuring		1
Post-modification outstanding recorded investment, TDRs that defaulted		$ 231,000
Commercial construction
Financing Receivable, Modifications [Line Items]
Number of restructurings | restructuring	0	1
Post-modification outstanding recorded investment	$ 0	$ 205,000
Pre-modification outstanding recorded investment	$ 0	$ 206,000
Number of TDRs that defaulted | restructuring		0
Post-modification outstanding recorded investment, TDRs that defaulted		$ 0
Residential
Financing Receivable, Modifications [Line Items]
Number of restructurings | restructuring	0	0
Post-modification outstanding recorded investment	$ 0	$ 0
Pre-modification outstanding recorded investment	$ 0	$ 0
Number of TDRs that defaulted | restructuring		0
Post-modification outstanding recorded investment, TDRs that defaulted		$ 0
Home Equity
Financing Receivable, Modifications [Line Items]
Number of restructurings | restructuring	0	0
Post-modification outstanding recorded investment	$ 0	$ 0
Pre-modification outstanding recorded investment	$ 0	$ 0
Number of TDRs that defaulted | restructuring		0
Post-modification outstanding recorded investment, TDRs that defaulted		$ 0
Consumer
Financing Receivable, Modifications [Line Items]
Number of restructurings | restructuring	0	0
Post-modification outstanding recorded investment	$ 0	$ 0
Pre-modification outstanding recorded investment	$ 0	$ 0
Number of TDRs that defaulted | restructuring		0
Post-modification outstanding recorded investment, TDRs that defaulted		$ 0
Extended Maturity
Financing Receivable, Modifications [Line Items]
Number of restructurings | restructuring	0	2
Post-modification outstanding recorded investment	$ 0	$ 3,063,000
Temporary payment reduction and payment re-amortization of remaining principal over extended term
Financing Receivable, Modifications [Line Items]
Number of restructurings | restructuring	2	1
Post-modification outstanding recorded investment	$ 139,000	$ 374,000
Temporary interest only payment plan
Financing Receivable, Modifications [Line Items]
Number of restructurings | restructuring	2	1
Post-modification outstanding recorded investment	$ 132,000	$ 94,000

Allowance For Loan Loss - Other

Allowance For Loan Loss - Other Real Estate Owned (Details)	3 Months Ended
	Mar. 31, 2018USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carry value of OREO	$ 0	$ 0	$ 0
Net gains on sales of OREO	0	$ 0
Consumer mortgage loans in process of foreclosure	$ 234,000		$ 101,000
Other real estate owned
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of OREO properties added	0	0
OREO fair value adjustment	$ 0	$ 0

Allowance For Loan Loss - Allow

Allowance For Loan Loss - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses to total loans ratio	1.51%	1.53%	1.45%
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	$ 32,915	$ 31,342
Provision for loan losses	1,600	125
Recoveries	114	352
Less: Charge offs	105	136
Ending Balance	34,524	31,683
Allocated to loans individually evaluated for impairment	2,854	2,374
Allocated to loans collectively evaluated for impairment	31,670	29,309
Commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	17,545	14,902
Provision for loan losses	755	316
Recoveries	0	76
Less: Charge offs	0	0
Ending Balance	18,300	15,294
Allocated to loans individually evaluated for impairment	52	409
Allocated to loans collectively evaluated for impairment	18,248	14,885
Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	9,669	11,204
Provision for loan losses	1,435	(195)
Recoveries	108	272
Less: Charge offs	41	103
Ending Balance	11,171	11,178
Allocated to loans individually evaluated for impairment	2,776	1,928
Allocated to loans collectively evaluated for impairment	8,395	9,250
Commercial construction
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	3,947	3,406
Provision for loan losses	(664)	(42)
Recoveries	0	0
Less: Charge offs	0	0
Ending Balance	3,283	3,364
Allocated to loans individually evaluated for impairment	0	23
Allocated to loans collectively evaluated for impairment	3,283	3,341
Residential
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	904	960
Provision for loan losses	10	18
Recoveries	0	0
Less: Charge offs	0	0
Ending Balance	914	978
Allocated to loans individually evaluated for impairment	4	0
Allocated to loans collectively evaluated for impairment	910	978
Home Equity
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	608	634
Provision for loan losses	20	0
Recoveries	1	1
Less: Charge offs	0	0
Ending Balance	629	635
Allocated to loans individually evaluated for impairment	0	0
Allocated to loans collectively evaluated for impairment	629	635
Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning Balance	242	236
Provision for loan losses	44	28
Recoveries	5	3
Less: Charge offs	64	33
Ending Balance	227	234
Allocated to loans individually evaluated for impairment	22	14
Allocated to loans collectively evaluated for impairment	$ 205	$ 220

Deposits (Details)

Deposits (Details) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Deposits [Abstract]
Non-interest bearing demand deposits		$ 717,656	$ 705,846
Interest-bearing checking		382,580	391,111
Savings		193,766	193,385
Money market		868,359	807,931
Certificates of deposit $250,000 or less		173,720	150,445
Certificates of deposit more than $250,000		49,814	45,154
Total customer deposits		2,385,895	2,293,872
Brokered deposits	[1]	185,494	147,490
Total deposits		2,571,389	2,441,362
Reciprocal deposits		$ 299,900	$ 249,600
[1]	Brokered CDs $250,000 and under.

Borrowed Funds and Subordinat49

Borrowed Funds and Subordinated Debt (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Jan. 31, 2015
Debt Instrument [Line Items]
Borrowed funds	$ 0	$ 89,000,000
Subordinated debt	$ 14,850,000	$ 14,847,000
Fixed-to Floating Rate Subordinated Notes
Debt Instrument [Line Items]
Subordinated debt			$ 15,000,000
Subordinated debt, term	15 years
Subordinated debt, rate until January 30, 2025	6.00%

Derivatives and Hedging Activ50

Derivatives and Hedging Activities (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2018USD ($)instrumentloan	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)instrumentloan
Derivative [Line Items]
Number of Participation Loans with Swap Contingent Liabilities | loan	2		2
Interest rate swap
Derivative [Line Items]
Gain (Loss) on Interest Rate Swaps	$ 0	$ 0
Number of Interest Rate Swaps | instrument	6		6
Aggregate notional value of interest-rate swaps	$ 29,200,000		$ 29,400,000
Fair Value of Interest-Rate Swap Assets	887,000		568,000
Fair Value of Interest-Rate Swap Liabilities	887,000		568,000
Counterparty Credit Risk Exposure on Interest Rate Swaps	887,000		543,000
Collateral received for interest-rate swaps	930,000		480,000
Receive Fixed Pay Variable | Interest rate swap
Derivative [Line Items]
Fair Value of Interest-Rate Swap Assets	0		25,000
Fair Value of Interest-Rate Swap Liabilities	887,000		568,000
Pay Fixed Receive Variable | Interest rate swap
Derivative [Line Items]
Fair Value of Interest-Rate Swap Assets	887,000		543,000
Fair Value of Interest-Rate Swap Liabilities	0		0
Gross Amount Interest Rate Swap Asset Recognized	887,000		568,000
Gross Amounts Interest Rate Swap Offset in the Statement of Financial Position	$ 0		$ 25,000

Stockholder's Equity (Details)

Stockholder's Equity (Details) - $ / shares	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Common stock, shares authorized	40,000,000	40,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares,outstanding	11,682,914	11,609,853
Common stock, shares issued	11,682,914	11,609,853
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares issued	0	0
Unvested participating restricted stock awards	121,999	117,219
Common Stock
Class of Stock [Line Items]
Common stock, voting rights	1
Series A Preferred Stock
Class of Stock [Line Items]
Preferred stock, par value	$ 0.01
Price per one one-hundredth of a share	$ 122.50
Minimum acquisition percentage to trigger the exercise of the right to purchase	10.00%
Amount of a share allowed to be purchased under right to purchase	0.01

Supplemental Retirement Plan 52

Supplemental Retirement Plan and Other Postretirement Benefit Obligations (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)officer	Mar. 31, 2017USD ($)
Supplemental Employee Retirement Plan
Defined Benefit Plan Disclosures [Line Items]
Number of Active Executive Officers under Plan | officer	2
Number of Former Executive Officers under Plan | officer	1
Term of SERP benefits	20 years
Net Periodic Benefit Cost	$ 26	$ 29
Benefits Paid	69	69
Remaining accrual for benefit obligation in current year	78
Supplemental Life Insurance
Defined Benefit Plan Disclosures [Line Items]
Net Periodic Benefit Cost	45	20
Service Cost	(17)	(3)
Interest Cost	$ 62	$ 23

Stock-Based Compensation Summar

Stock-Based Compensation Summary Information for Options Granted (Details) - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option granted	14,755	15,009
Per share weighted average fair value	$ 11.98	$ 11.34
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term in years	10 years	10 years
Expected volatility	37.00%	40.00%
Weighted average market price on date of grants	$ 34.33	$ 30.46
Weighted Average | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	2.10%	2.09%
Expected life in years	6 years 6 months	7 years
Risk-free interest rate	2.86%	2.35%
Fair Value as a percentage of market value at grant date	35.00%	37.00%

Stock-Based Compensation Stock

Stock-Based Compensation Stock Options, Stock Awards, and Stock in Lieu of Directors' Fees (Details) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		12 Months Ended
	Jan. 31, 2018shares	Mar. 31, 2018USD ($)plansshares	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)	Jan. 03, 2017$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of individual stock incentive plans | plans		2
Shares remaining available for future grants | shares		409,301
Stock-based compensation expense		$ 385	$ 324
Income tax benefit for stock compensation in Income Statement		195	667
Number of shares issued in lieu of cash to directors | shares	7,326
Fair market share price | $ / shares					$ 38.39
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		$ 51	62
Restricted stock | Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		4 years
Restricted stock | Non-Employee Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		2 years
Restricted stock and common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		$ 259	187
Common stock in lieu of cash | Non-Employee Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		$ 75	$ 75	$ 281
Vesting, Year Two | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted, vesting percentage		50.00%	50.00%
Vesting, Year Four | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted, vesting percentage		50.00%	50.00%

Stock-Based Compensation Restri

Stock-Based Compensation Restricted Stock Grants (Details) - Restricted stock - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards in the period	44,505	48,820
Weighted Average Grant Date Fair Value, Stock Awards	$ 34.33	$ 30.46
Non-Employee Director | Two year vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards in the period	7,280	6,944
Employee | Four year vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards in the period	16,666	16,253
Employee | Performance-based vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards in the period	20,559	25,623

Earnings Per Share Earnings Per

Earnings Per Share Earnings Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Basic weighted average common shares outstanding	11,628,587	11,508,811
Dilutive shares	72,267	90,051
Diluted weighted average common shares outstanding	11,700,854	11,598,862
Antidilutive shares excluded from EPS	29,353

Fair Value Measurements - Recur

Fair Value Measurements - Recurring and Nonrecurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Specific allowance for collateral dependent impaired loans	$ 1,400	$ 872
Letter of Credit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amortization period of estimated fair value on letters of credit	1 year
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1 | Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of liabilities	$ 0	0
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1 | Debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	0	0
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1 | Equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	295
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1 | FHLB Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	0	0
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1 | Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	0	0
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of liabilities	887	568
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	412,213	405,206
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	0
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | FHLB Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	0	0
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	887	568
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 | Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of liabilities	0	0
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 | Debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	0	0
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 | Equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	0
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 | FHLB Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	2,370	5,215
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 | Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	0	0
Fair Value, Measurements, Nonrecurring | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans (collateral dependent), Fair Value	0	0
Fair Value, Measurements, Nonrecurring | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans (collateral dependent), Fair Value	0	0
Fair Value, Measurements, Nonrecurring | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans (collateral dependent), Fair Value	2,424	2,696
Fair Value | Fair Value, Measurements, Recurring | Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of liabilities	887	568
Fair Value | Fair Value, Measurements, Recurring | Debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	412,213	405,206
Fair Value | Fair Value, Measurements, Recurring | Equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	295
Fair Value | Fair Value, Measurements, Recurring | FHLB Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	2,370	5,215
Fair Value | Fair Value, Measurements, Recurring | Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of assets	887	568
Fair Value | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans (collateral dependent), Fair Value	$ 2,424	$ 2,696

Fair Value Measurements - Quant

Fair Value Measurements - Quantitative (Details) - Fair Value, Inputs, Level 3 - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Dec. 31, 2017
Fair Value, Measurements, Recurring | FHLB Stock
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value of assets		$ 2,370	$ 5,215
Fair Value, Measurements, Recurring | FHLB Stock | FHLB stated par value
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value of assets		2,370
Fair Value, Measurements, Nonrecurring
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Impaired loans (collateral dependent), Fair Value		2,424	$ 2,696
Fair Value, Measurements, Nonrecurring | Impaired loans (collateral dependent) | Appraisal of collateral
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Impaired loans (collateral dependent), Fair Value	[1]	$ 2,424
Fair Value, Measurements, Nonrecurring | Impaired loans (collateral dependent) | Appraisal of collateral | Minimum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Unobservable Input Value or Range		5.00%
Fair Value, Measurements, Nonrecurring | Impaired loans (collateral dependent) | Appraisal of collateral | Maximum
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Unobservable Input Value or Range		50.00%
[1]	Appraisals may be adjusted by management for qualitative factors such as economic conditions and estimated liquidation expenses.

Fair Value Measurements - Balan

Fair Value Measurements - Balance Sheet Grouping (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Carrying Amount
Financial assets:
Loans held for sale		$ 208
Loans, net	$ 2,255,649	2,236,989
Financial liabilities:
Borrowed Funds		89,000
Subordinated debt	14,850	14,847
Carrying Amount | Certificates of Deposit
Financial liabilities:
Certificates of deposit	409,028	343,089
Fair Value
Financial assets:
Loans held for sale		208
Loans, net	2,237,319	2,236,169
Financial liabilities:
Borrowed Funds		88,996
Subordinated debt	13,949	14,208
Fair Value | Certificates of Deposit
Financial liabilities:
Certificates of deposit	406,487	341,765
Fair Value, Inputs, Level 1
Financial assets:
Loans held for sale		0
Loans, net	0	0
Financial liabilities:
Borrowed Funds		0
Subordinated debt	0	0
Fair Value, Inputs, Level 1 | Certificates of Deposit
Financial liabilities:
Certificates of deposit	0	0
Fair Value, Inputs, Level 2
Financial assets:
Loans held for sale		208
Loans, net	0	0
Financial liabilities:
Borrowed Funds		88,996
Subordinated debt	0	0
Fair Value, Inputs, Level 2 | Certificates of Deposit
Financial liabilities:
Certificates of deposit	406,487	341,765
Fair Value, Inputs, Level 3
Financial assets:
Loans held for sale		0
Loans, net	2,237,319	2,236,169
Financial liabilities:
Borrowed Funds		0
Subordinated debt	13,949	14,208
Fair Value, Inputs, Level 3 | Certificates of Deposit
Financial liabilities:
Certificates of deposit	$ 0	$ 0