Cambridge Bancorp (CATC) 10-K 16 Mar 23 2022 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Mar. 09, 2023	Jun. 30, 2022
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Trading Symbol	CATC
Entity Registrant Name	CAMBRIDGE BANCORP
Entity Central Index Key	0000711772
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity Emerging Growth Company	false
Entity Small Business	false
Title of 12(b) Security	Common Stock
Security Exchange Name	NASDAQ
Entity Public Float			$ 528.7
Entity Common Stock, Shares Outstanding		7,834,057
Entity File Number	001-38184
Entity Incorporation, State or Country Code	MA
Entity Tax Identification Number	04-2777442
Entity Address, Address Line One	1336 Massachusetts Avenue
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02138
City Area Code	617
Local Phone Number	876-5500
Document Annual Report	true
Document Transition Report	false
ICFR Auditor Attestation Flag	true
Documents Incorporated by Reference	Portions of the Registrant’s Definitive Proxy Statement relating to the Annual Meeting of Shareholders, scheduled to be held on May 15, 2023, are incorporated by reference into Part III of this Report.
Auditor Name	Wolf & Company, P.C.
Auditor Location	Boston, Massachusetts
Auditor Firm ID	392

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Assets
Cash and cash equivalents	$ 30,719	$ 180,153
Investment securities
Available for sale, at fair value (amortized cost $182,027 and $201,270, respectively)	153,416	197,803
Held to maturity, at amortized cost (fair value $885,586 and $971,092, respectively)	1,051,997	977,061
Total investment securities	1,205,413	1,174,864
Loans held for sale, at lower of cost or fair value		1,490
Loans
Total loans	4,062,856	3,319,106
Less: allowance for credit losses on loans	(37,774)	(34,496)
Net loans	4,025,082	3,284,610
Federal Home Loan Bank ("FHLB") of Boston Stock, at cost	6,264	4,816
Bank owned life insurance	34,484	46,970
Banking premises and equipment, net	23,297	17,326
Right-of-use asset operating leases	25,098	31,273
Deferred income taxes, net	17,990	9,985
Accrued interest receivable	14,118	9,162
Goodwill	64,539	51,912
Merger related intangibles, net	7,443	2,617
Other assets	105,290	76,366
Total assets	5,559,737	4,891,544
Deposits
Demand	1,366,395	1,393,935
Interest bearing checking	908,961	763,188
Money market	1,162,773	1,104,238
Savings	790,628	907,722
Certificates of deposit	586,619	162,069
Total deposits	4,815,376	4,331,152
Borrowings	105,212	16,510
Operating lease liabilities	27,413	33,871
Other liabilities	94,184	72,174
Total liabilities	5,042,185	4,453,707
Shareholders’ Equity
Common stock, par value $1.00; Authorized 10,000,000 shares; Outstanding: 7,796,440 shares and 6,968,192 shares, respectively	7,796	6,968
Additional paid-in capital	293,186	229,205
Retained earnings	237,369	202,874
Accumulated other comprehensive loss	(20,799)	(1,210)
Total shareholders’ equity	517,552	437,837
Total liabilities and shareholders’ equity	5,559,737	4,891,544
Residential Mortgage
Loans
Total loans	1,648,838	1,415,079
Commercial Mortgage
Loans
Total loans	1,914,423	1,511,002
Home Equity
Loans
Total loans	111,351	87,960
Commercial and Industrial
Loans
Total loans	350,650	269,446
Consumer
Loans
Total loans	$ 37,594	$ 35,619

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Available for sale securities, amortized cost	$ 182,027	$ 201,270
Held-to-maturity securities, fair value	$ 885,586	$ 971,092
Common stock, par value	$ 1	$ 1
Common stock, shares authorized	10,000,000	10,000,000
Common stock, shares, outstanding	7,796,440	6,968,192

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Interest and dividend income
Interest on taxable loans	$ 135,965	$ 120,019	$ 119,447
Interest on tax-exempt loans	1,447	1,205	880
Interest on taxable investment securities	19,555	9,464	6,048
Interest on tax-exempt investment securities	2,477	2,630	2,485
Dividends on FHLB of Boston stock	287	46	331
Interest on overnight investments	262	150	187
Total interest and dividend income	159,993	133,514	129,378
Interest expense
Interest on deposits	14,598	4,974	7,295
Interest on borrowed funds	2,180	559	1,406
Interest on subordinated debt			444
Total interest expense	16,778	5,533	9,145
Net interest and dividend income	143,215	127,981	120,233
Provision for (release of) credit losses	3,881	(1,294)	18,310
Net interest and dividend income after provision for (release of) credit losses	139,334	129,275	101,923
Noninterest income
Bank owned life insurance income	1,808	801	747
Gain (loss) on disposition of investment securities			69
Gain on loans sold, net	98	832	1,850
Loan related derivative income	625	2,124	1,479
Other income	2,868	2,024	1,726
Total noninterest income	43,009	44,324	39,525
Noninterest expense
Salaries and employee benefits	70,109	65,127	58,975
Occupancy and equipment	14,364	13,898	13,004
Data processing	10,706	8,829	7,662
Professional services	4,728	5,391	4,190
Marketing	2,301	2,536	1,818
FDIC insurance	1,845	1,318	992
Non-operating expenses	3,059	1,118	7,612
Other expenses	3,270	2,267	3,832
Total noninterest expense	110,382	100,484	98,085
Income before income taxes	71,961	73,115	43,363
Income tax expense	19,052	19,091	11,404
Net Income	$ 52,909	$ 54,024	$ 31,959
Share data:
Weighted average shares outstanding, basic	7,163,223	6,926,257	6,289,481
Weighted average shares outstanding, diluted	7,213,913	6,990,603	6,344,409
Basic earnings per share	$ 7.35	$ 7.76	$ 5.07
Diluted earnings per share	$ 7.30	$ 7.69	$ 5.03
Wealth Management Revenue
Noninterest income
Noninterest income	$ 33,034	$ 35,037	$ 29,751
Deposit Account Fees
Noninterest income
Noninterest income	2,913	1,939	2,595
ATM/Debit Card Income
Noninterest income
Noninterest income	$ 1,663	$ 1,567	$ 1,308

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income		$ 52,909	$ 54,024	$ 31,959
Available for sale securities
Unrealized holding gains (losses)		(18,736)	(4,622)	2,800
Reclassification adjustment for losses realized in net income	[1]			(57)
Total unrealized losses on available for sale securities		(18,736)	(4,622)	2,743
Interest rate swaps designated as cash flow hedges
Unrealized holding gains (losses)		(1,563)	(959)	4,758
Reclassification adjustment for gains (losses) realized in net income	[2]	(600)	(1,864)	(1,354)
Total unrealized losses on interest rate swaps		(2,163)	(2,823)	3,404
Defined benefit retirement plans
Change in retirement liabilities		1,310	3,801	(1,232)
Other comprehensive income (loss)		(19,589)	(3,644)	4,915
Comprehensive income		$ 33,320	$ 50,380	$ 36,874
[1] Reported in gain (loss) on disposition of investment securities line item in the Consolidated Statements of Income. Reported in interest on payable loans line item in the Consolidated Statements of Income.

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Wellesley Bancorp Inc	North Mark Merger	Common Stock	Common Stock Wellesley Bancorp Inc	Common Stock North Mark Merger	Additional Paid-In Capital	Additional Paid-In Capital Wellesley Bancorp Inc	Additional Paid-In Capital North Mark Merger	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income / (Loss)
Beginning balance at Dec. 31, 2019	$ 286,561	$ (347)			$ 5,401			$ 136,766			$ 146,875	$ (347)	$ (2,481)
Accounting Standards Update [Extensible List]	ASU 2020-04				ASU 2020-04			ASU 2020-04			ASU 2020-04		ASU 2020-04
Net income	$ 31,959										$ 31,959
Other comprehensive income (loss)	4,915												$ 4,915
Share based compensation and other share-based activity	4,564				$ 23			$ 4,541
Dividends declared	(13,083)										(13,083)
Common stock issued for merger			$ 87,163			$ 1,503			$ 85,660
Ending balance at Dec. 31, 2020	401,732				6,927			226,967			165,404		2,434
Net income	54,024										54,024
Other comprehensive income (loss)	(3,644)												(3,644)
Share based compensation and other share-based activity	2,279				41			2,238
Dividends declared	(16,554)										(16,554)
Ending balance at Dec. 31, 2021	437,837				6,968			229,205			202,874		(1,210)
Net income	52,909										52,909
Other comprehensive income (loss)	(19,589)												(19,589)
Share based compensation and other share-based activity	1,959				39			1,920
Dividends declared	(18,414)										(18,414)
Common stock issued for merger				$ 62,850			$ 789			$ 62,061
Ending balance at Dec. 31, 2022	$ 517,552				$ 7,796			$ 293,186			$ 237,369		$ (20,799)

CONSOLIDATED STATEMENTS OF CH_2

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Retained Earnings
Dividends declared, per share	$ 2.56	$ 2.38	$ 2.12

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 52,909	$ 54,024	$ 31,959
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for (Release of) credit losses	3,881	(1,294)	18,310
Amortization (accretion) of deferred charges and fees, net	2,282	(1,434)	(780)
Depreciation (accretion), and amortization, net	726	(1,838)	(8,134)
Bank owned life insurance income	(1,808)	(801)	(747)
(Gain) loss on disposition of investment securities			(69)
Share-based compensation and other share-based activity	1,959	2,279	4,564
Change in accrued interest receivable	(4,280)	352	253
Deferred income tax expense	587	2,899	(665)
Change in loans held for sale	1,490	5,419	(5,363)
Change in other assets, net	(32,056)	5,473	(22,863)
Change in other liabilities, net	26,260	429	20,332
Net cash provided by operating activities	51,950	65,508	36,797
CASH FLOWS FROM INVESTING ACTIVITIES
Origination of loans	(1,265,305)	(1,327,044)	(1,070,321)
Proceeds from principal payments of loans	850,886	1,170,430	1,022,516
Purchase of loans	(23,655)
Proceeds from calls/maturities of securities available for sale	29,040	42,169	47,087
Purchase of securities available for sale	(10,170)	(9,927)	(140,570)
Proceeds from sales of securities	19,018		10,821
Proceeds from calls/maturities of securities held to maturity	132,173	70,800	56,007
Purchase of securities held to maturity	(205,137)	(801,775)	(33,818)
Death benefit on bank-owned life insurance	4,025
Redemption on bank-owned life insurance	10,759
(Purchase) redemption of FHLB of Boston stock	(1,215)	918	8,505
Purchase of banking premises and equipment	(1,776)	(2,033)	(2,218)
Net cash acquired in business combinations	82,174		43,063
Net cash used in investing activities	(379,183)	(856,462)	(58,928)
CASH FLOWS FROM FINANCING ACTIVITIES
Change in demand, interest bearing, money market and savings accounts	(216,751)	1,020,821	422,866
Change in certificates of deposit	327,938	(92,552)	(138,213)
Change in short term borrowings	85,026	(16,393)	(224,989)
Redemption of subordinated debt			(10,000)
Cash dividends paid on common stock	(18,414)	(16,554)	(13,083)
Net cash provided by financing activities	177,799	895,322	36,581
Net change in cash and cash equivalents	(149,434)	104,368	14,450
Cash and cash equivalents at beginning of period	180,153	75,785	61,335
Cash and cash equivalents at end of period	30,719	180,153	75,785
Cash paid during the period for:
Interest	15,805	5,656	9,172
Income taxes	21,822	$ 9,054	14,628
Significant non-cash transactions
Transfer of other real estate owned			2,293
Common Stock issued to shareholders due to merger	62,850		87,163
Fair value of assets acquired, net of cash acquired	346,501		961,668
Fair value of liabilities assumed	$ 378,453		$ 917,569

The Business

The Business	12 Months Ended
	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
The Business	1. THE BUSINESS The accompanying consolidated financial statements include the accounts of Cambridge Bancorp (the “Company”) and its wholly owned subsidiary, Cambridge Trust Company (the “Bank”), and the Bank’s subsidiaries, Cambridge Trust Company of New Hampshire, Inc., CTC Security Corporation, and CTC Security Corporation III. References to the Company herein relate to the consolidated group of companies. All significant intercompany accounts and transactions have been eliminated in preparation of the consolidated financial statements. The Company is a state-chartered, federally registered bank holding company headquartered in Cambridge, Massachusetts, incorporated in 1983. The Company is the sole shareholder of the Bank, a Massachusetts trust company chartered in 1890 which is a commercial bank. The Company is a private bank offering a full range of private banking and wealth management services to its clients. The private banking business, the Company’s only reportable operating segment, is managed as a single strategic unit. As a private bank, the Company focuses on four core services that center around client needs. The core services include Wealth Management, Commercial Banking, Residential Lending, and Personal Banking. The Bank offers a full range of commercial and consumer banking services through its network of 22 banking offices in Massachusetts and New Hampshire. The Bank is engaged principally in the business of attracting deposits from the public and investing those deposits. The Bank invests those funds in various types of loans, including residential and commercial real estate, and a variety of commercial and consumer loans. The Bank also invests its deposits and borrowed funds in investment securities and has two wholly owned Massachusetts security corporations, CTC Security Corporation and CTC Security Corporation III, for this purpose. Deposits at the Bank are insured by the Federal Deposit Insurance Corporation (“FDIC”) for the maximum amount permitted by FDIC Regulations. Trust and investment management services are offered through the Bank’s private banking offices in Massachusetts and New Hampshire, and its wealth management offices located in Boston and Wellesley, Massachusetts and Concord, Manchester, and Portsmouth, New Hampshire. The Bank also has a non-depository trust company, Cambridge Trust Company of New Hampshire, Inc., which allows non-New Hampshire residents the opportunity to take advantage of the state’s favorable trust laws. The assets held for wealth management clients are not assets of the Bank and, accordingly, are not reflected in the accompanying consolidated balance sheets.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”). Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements. Actual results could differ from those estimates. The allowance for credit losses, the valuation of deferred tax assets, and the valuation of assets acquired and liabilities assumed in business combinations are particularly subject to change. Reclassifications Certain amounts in the prior year’s financial statements may have been reclassified to conform with the current year’s presentation. Cash and Cash Equivalents Cash and cash equivalents consist of cash on hand, amounts due from banks, and overnight investments. Investment Securities Investment securities are classified as either “held to maturity” or “available for sale” in accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 320, Investments – Debt Securities. Debt securities that management has the positive intent and ability to hold to maturity are classified as held to maturity and recorded at amortized cost. Debt securities not classified as held to maturity are classified as available for sale and carried at fair value with unrealized after-tax gains and losses reported net as a separate component of shareholders’ equity. The Company classifies its securities based on its intention at the time of purchase. Purchase premiums and discounts are recognized in interest income using the effective yield or straight-line method over the term of the securities, except for callable debt securities for which the purchase premiums are recognized through the earliest call date. Gains and losses on the sale of debt securities are recorded on the trade date and determined using the specific identification method. Allowance for Credit Losses - Held to Maturity Securities The Company measures expected credit losses on held to maturity debt securities on a collective basis by security type and risk rating where available. The reserve for each pool is calculated based on a Probability of Default/Loss Given Default (“PD/LGD”) basis taking into consideration the expected life of each security. Held to maturity securities which are issued by the United States of America (“U.S.”) or are guaranteed by U.S. federal agencies do not currently have an allowance for credit loss as the Company determined these securities are either backed by the full faith and credit of the U.S. government and/or there is an unconditional commitment to make interest payments and to return the principal investment in full to investors when a debt security reaches maturity. The Company will evaluate this position no less than annually, however, certain items which may cause the Company to change this methodology include legislative changes that remove a government-sponsored enterprise’s (“GSE”) ability to draw funds from the U.S. government, or legislative changes to housing policy that reduce or eliminate the U.S. government’s implicit guarantee on such securities. For securities which are not U.S. treasury or agency backed, risk ratings are generally sourced from Moody’s or Standard & Poor’s. The Company updates loss given default, probability of default, and recovery rates for each security as that information becomes available but no less than annually. The expected remaining life to maturity of each applicable security is updated quarterly. Any expected credit losses on held to maturity securities would be presented as an allowance rather than as a direct write-down through the consolidated statements of income if the Company does not intend to sell or believes that it is more likely than not that the Company will be required to sell the security. Allowance for Credit Losses - Available for Sale Securities The Company measures expected credit losses on available for sale securities based upon the gain or loss position of the security. For available for sale debt securities in an unrealized loss position, which the Company does not intend to sell, or it is not more likely than not that the Company will be required to sell the security before recovery of the Company’s amortized cost, the Company evaluates qualitative criteria to determine any expected loss. This includes among other items the financial health of, and specific prospects for the issuer, including whether the issuer is in compliance with the terms and covenants of the security. The Company also evaluates quantitative criteria including determining whether there has been an adverse change in expected future cash flows of the security. If the Company does not expect to recover the entire amortized cost basis of the security, an allowance for credit losses would be recorded, with a related charge to earnings, limited by the amount of the fair value of the security less its amortized cost. If the Company intends to sell the security or it is more likely than not that the Company will be required to sell the debt security before recovery of its amortized cost basis, the Company recognizes the entire difference between the security’s amortized cost basis and its fair value in earnings. Loans Loans are reported at the amount of their outstanding principal, including deferred loan origination fees and costs, reduced by unearned discounts, and the allowance for credit losses. Loans are considered delinquent when a payment of principal and/or interest becomes past due 30 days following its scheduled payment due date. Loans on which the accrual of interest has been discontinued are designated as non-accrual loans. Loans are removed from non-accrual when they become less than 90 days past due and when concern no longer exists as to the collectability of principal or interest. Allowance for Credit Losses - Loans Losses on loan receivables are estimated and recognized upon origination of the loan, based on expected credit losses for the life of the loan balance as of the period end date. The Company’s methodology for calculating the allowance for credit losses (“ACL”) on loans consists of quantitative and qualitative components. The Company uses a discounted cash flow method incorporating probability of default and loss given default forecasted based on statistically derived economic variable loss drivers combined with qualitative factors, to estimate expected credit losses. This process includes estimates which involve modeling loss projections attributable to existing loan balances, considering historical experience, current conditions, and future expectations for homogeneous pools of loans over the reasonable and supportable forecast period. The reasonable and supportable forecast period is determined based upon the accuracy level of historical loss forecast estimates, the specific loan level models and methodology utilized, and considers material changes in growth and credit strategy, and business changes. For periods beyond a reasonable and supportable forecast interval, the Company reverts to historical information over a period for which comparable data is available. The historical information either experienced by the Company, or by a selection of peer banks when appropriate, is derived from a combination of recessionary and non-recessionary performance periods for which data is available. Similar to the reasonable and supportable forecast period, the Company reassesses the reversion period at the segment level, considering any required adjustments for differences in underwriting standards, portfolio mix, and other relevant data shifts over time. The Company generally segments its loan receivable population into homogeneous pools of loans. Consistent with the Company’s other assumptions, the Company regularly reviews segmentation to determine whether the homogeneous pools remain relevant as risk characteristics change. When a loan no longer meets the criteria of its initial pooling as a result of credit deterioration or other changes, the Company may evaluate the credit for estimated losses on an individual basis if the Company determines that the credit no longer retains the same risk characteristics. To the extent that there are a multitude of these loans with new similar risk characteristics, the Company would anticipate a change to the pooling methodology. Loans that do not share risk characteristics are evaluated on an individual basis and are not included in the collective evaluation. For loans with real estate collateral, when management determines that foreclosure is probable, expected credit losses are based on the fair value of the collateral at the reporting date, adjusted for selling costs as appropriate. The qualitative component of the ACL considers (i) the uncertainty of forward-looking scenarios; (ii) certain portfolio characteristics, such as portfolio concentrations, real estate values, changes in the number and amount of non-accrual and past due loans; and (iii) model limitations; among other factors. Qualitative adjustments are considered when management believes expected credit losses are not representative of historical loss experience alone, and should be adjusted to reflect the current conditions and characteristics of the Company’s own portfolio. They are made at the segment level, considering any required adjustments for differences in underwriting standards, portfolio mix, and other relevant data shifts over time. The Company evaluates the allowance for credit losses on loans quarterly. The Company regularly reviews its collection experience (including delinquencies and net charge-offs) in determining its allowance for credit losses. The Company also considers its historical loss experience to date based on actual defaulted loans and overall portfolio indicators including delinquent and non-accrual loans, trends in loan volume and lending terms, credit policies and other observable environmental factors such as unemployment and interest rate changes. The underlying assumption estimates and assessments the Company uses to estimate the allowance for credit losses reflects the Company’s best estimate of model assumptions and forecasted conditions at that time. Changes in such estimates can significantly affect the allowance and provision for (release of) credit losses. It is possible and likely that the Company will experience credit losses that are different from the current estimates. The provision for (release of) credit losses charged to income is based on management’s judgment of the amount necessary to maintain the allowance at a level to provide for expected credit losses for the life of the loan balances as of the evaluation date. When management believes that the collectability of a loan’s principal balance, or portions thereof, is unlikely, the principal amount is charged against the allowance for credit losses. Recoveries on loans that have been previously charged off are credited to the allowance for credit losses, generally at the time cash is received on a charged-off account. The allowance is an estimate, and ultimate losses may vary from current estimates. As adjustments become necessary, they are reported in the results of operations through the provision for (release of) credit losses in the period in which they become known. Risk characteristics relevant to each portfolio segment are as follows: Residential mortgage and home equity loans – The Company generally does not originate loans in these segments with a loan-to-value ratio greater than 80 %, unless covered by private mortgage insurance, and in all cases not greater than a loan-to-value ratio of 97 %. The Company does not originate subprime loans. Loans in these segments are secured by one-to-four family residential real estate, and repayment is primarily dependent on the credit quality of the individual borrower. Commercial mortgage loans – This includes multi-family properties and construction. The Company generally does not originate loans in this segment with a loan-to-value ratio greater than 75 % . Loans in this segment are secured by owner-occupied and nonowner-occupied commercial real estate (“CRE”), and repayment is primarily dependent on the cash flows of the property (if nonowner-occupied) or of the business (if owner-occupied). Commercial and industrial loans (“C&I”) – Loans in this segment are made to businesses and are generally secured by equipment, accounts receivable, or inventory, as well as the personal guarantees of the principal owners of the business, and repayment is primarily dependent on the cash flows generated by the business. In addition, this segment includes certain loans issued under the U. S. Small Business Administration’s (“SBA”) Paycheck Protection Program (“PPP”). These loans are guaranteed and are not evaluated for an allowance for credit losses because the Company expects the guarantees will be effective, if necessary. Consumer loans – Loans in this segment are made to individuals and can be secured or unsecured. Repayment is primarily dependent on the credit quality of the individual borrower. The majority of the Company’s loans are concentrated in Eastern Massachusetts and Southern New Hampshire and therefore the overall health of the local economy, including unemployment rates, vacancy rates, and consumer spending levels, can have a material effect on the credit quality of all of these portfolio segments. The process to determine the allowance for credit losses requires management to exercise considerable judgment regarding the risk characteristics of the loan portfolio segments and the effect of relevant internal and external factors. Allowance for Credit Losses - Unfunded Commitments The expected credit losses for unfunded commitments are measured over the contractual period of the Company’s exposure to credit risk. The estimate of credit loss incorporates assumptions for both the likelihood and amount of funding over the estimated life of the commitments, for the risk of loss, and current conditions and expectations. Management periodically reviews and updates its assumptions for estimated funding rates based on historical rates, and factors such as portfolio growth, changes to organizational structure, economic conditions, borrowing habits, or any other factor which could impact the likelihood that funding will occur. The Company does not reserve for unfunded commitments which are unconditionally cancellable. Acquired Loans Acquired loans are recorded at fair value at the date of acquisition based on a discounted cash flow methodology that considers various factors, including the type of loan and related collateral, classification status, fixed or variable interest rate, term of loan and whether or not the loan was amortizing, and a discount rate reflecting the Company’s assessment of risk inherent in the cash flow estimates. Purchased loans are grouped together according to similar risk characteristics and are treated in the aggregate when applying various valuation techniques. These cash flow evaluations are inherently subjective as they may be susceptible to significant change. Effective January 1, 2020, loans acquired in a business combination that have experienced more-than-insignificant deterioration in credit quality since origination are considered purchased credit deteriorated (“PCD”) loans. The Company evaluates acquired loans for deterioration in credit quality based on, but not limited to, the following: (1) non-accrual status; (2) troubled debt restructured designation; (3) risk ratings of special mention, substandard or doubtful; (4) watchlist credits; and (5) delinquency status, including loans that are current on acquisition date, but had been previously delinquent. At the acquisition date, an estimate of expected credit losses is made for groups of PCD loans with similar risk characteristics and individual PCD loans without similar risk characteristics. This initial allowance for credit losses is allocated to individual PCD loans and added to the purchase price or acquisition date fair values to establish the initial amortized cost basis of the PCD loans. As the initial allowance for credit losses is added to the purchase price, there is no credit loss expense recognized upon acquisition of a PCD loan. Any difference between the unpaid principal balance of PCD loans and the amortized cost basis is considered to relate to noncredit factors and results in a discount or premium. Discounts and premiums are recognized through interest income on a level-yield method over the life of the loans. For acquired loans not deemed PCD at acquisition, the differences between the initial fair value and the unpaid principal balance are recognized as interest income on a level-yield basis over the lives of the related loans. At the acquisition date, an initial allowance for expected credit losses is estimated and recorded as provision for credit losses. The subsequent measurement of expected credit losses for all acquired loans is the same as the subsequent measurement of expected credit losses for originated loans. Allowance for Loan Losses Prior to the adoption of ASC Topic 326 – Financial Instruments – Credit Losses (“CECL”) on January 1, 2020, the Company calculated its provision for loan losses and the level of the allowance for loan losses to reflect management’s estimate of probable loan losses inherent in the loan portfolio at the balance sheet date. Management used a systematic process and methodology to establish the allowance for loan losses each quarter. To determine the total allowance for loan losses, an estimate was made by management of the allowance needed for each of the following segments of the loan portfolio: (a) residential mortgage loans, (b) commercial mortgage loans, (c) home equity loans, (d) C&I loans, and (e) consumer loans. Portfolio segments were further disaggregated into classes of loans. The establishment of the allowance for each portfolio segment was based on a process that evaluated the risk characteristics relevant to each portfolio segment and took into consideration multiple internal and external factors. Internal factors included, but were not limited to, (a) historic levels and trends in charge-offs, delinquencies, risk ratings, and foreclosures, (b) level and changes in industry, geographic, and credit concentrations, (c) underwriting policies and adherence to such policies, (d) the growth and vintage of the portfolios, and (e) the experience of, and any changes in, lending and credit personnel. External factors included, but were not limited to, (a) conditions and trends in the local and national economy and (b) levels and trends in national delinquent and non-performing loans. The Company evaluated certain loans individually for specific impairment. A loan was considered impaired when, based on current information and events, it was probable that the Company would be unable to collect the scheduled payments of principal or interest when due according to the contractual terms of the loan agreement. Loans that experienced insignificant payment delays and payment shortfalls generally were not classified as impaired. Loans were selected for evaluation based upon internal risk rating, delinquency status, or non-accrual status. A specific allowance amount was allocated to an individual loan when such loan had been deemed impaired and when the amount of the probable loss was able to be estimated. Estimates of loss were determined by the present value of anticipated future cash flows, the loan’s observable fair market value, or the fair value of the collateral, if the loan was collateral dependent. Loans Held for Sale Residential mortgage loans originated and intended for sale in the secondary market are classified as held for sale at the time of their origination and are carried at the lower of cost or fair value on an individual loan basis. Changes in fair value relating to loans held for sale below the loans cost basis are charged against gain on loans sold. Gains and losses on the actual sale of the residential loans are recorded in earnings as gains on loans sold, net on the consolidated statements of income. Bank Owned Life Insurance Bank owned life insurance (“BOLI”) represents life insurance on the lives of certain active and former employees who have provided positive consent allowing the Company to be the beneficiary of such policies. Since the Company is the primary beneficiary of the insurance policies, increases in the cash value of the policies, as well as insurance proceeds received in excess of cash surrender value, are recorded in noninterest income, and are not subject to income taxes. Applicable regulations generally limit the Company’s investment in BOLI to 25 % of its Tier 1 capital plus its allowance for credit losses. The Company reviews the financial strength of the insurance carriers prior to the purchase of BOLI and at least annually thereafter. Banking Premises and Equipment Land is stated at cost. Buildings, leasehold improvements, and equipment are stated at cost, less accumulated depreciation, and amortization, which is computed using the straight-line method over the estimated useful lives of the assets or the terms of the leases, if shorter. The cost of ordinary maintenance and repairs is charged to expense when incurred. Leases The Company leases office space and certain branch locations under noncancelable operating leases, several of which have renewal options to extend lease terms. Upon commencement of a new lease, the Company will recognize a right-of-use (“ROU”) asset and corresponding lease liability. The Company makes the decision on whether to renew an option to extend a lease by considering various factors. The Company will recognize an adjustment to its ROU asset and lease liability when lease agreements are amended and executed. The discount rate used in determining the present value of lease payments is based on the Company’s incremental borrowing rate for borrowings with terms similar to each lease at commencement date. The Company has lease agreements with lease and non-lease components, which are generally accounted for separately. For real estate leases, non-lease components and other non-components, such as common area maintenance charges, real estate taxes, and insurance, are not included in the measurement of the lease liability since they are generally able to be segregated. Marketing Expense Advertising costs are expensed as incurred. Other Real Estate Owned Other real estate owned consists of properties formerly pledged as collateral to loans, which have been acquired by the Company through foreclosure proceedings or acceptance of a deed in lieu of foreclosure. Upon transfer of a loan to foreclosure status, an appraisal is obtained and any excess of the loan balance over the fair value, less estimated costs to sell, is charged against the allowance for credit losses. Expenses and subsequent adjustments to the fair value are treated as noninterest expense through other expenses. Goodwill, Core Deposit Intangibles, and Other Intangible Assets Goodwill represents the excess of the purchase price over the fair value of net assets acquired in a business combination. Core deposit intangible (“CDI”) represents a premium paid to acquire the core deposits of an institution and is recorded as an intangible asset. Goodwill and intangible assets that are not amortized are tested for impairment, based on their fair values, at least annual ly. There was no goodwill impairment recognized during 2022, 2021, or 2020. Identifiable intangible assets that are subject to amortizatio n are also reviewed for impairment based on their fair value. Any impairment is recognized as a charge to earnings and the adjusted carrying amount of the intangible asset becomes its new accounting basis. The remaining useful life of an intangible asset that is being amortized is also evaluated each reporting period to determine whether events and circumstances warrant a revision to the remaining period of amortization. The Company is amortizing the CDI on a straight-line basis over a ten-year period. Mortgage servicing rights (“MSR”) are recognized as separate assets when rights are acquired through purchase or through sale of financial assets with servicing rights retained. The fair value of the servicing rights is determined by estimating the present value of future net cash flows, taking into consideration market loan prepayment speeds, discount rates, servicing costs, and other economic factors. For purposes of measuring impairment, the underlying loans are generally stratified into relatively homogeneous pools based on predominant risk characteristics. Because of the small size of this asset class, and its relative homogeneity, only one stratum is used. I f the aggregate carrying value of the capitalized mortgage servicing rights for this stratum exceeds its fair value, MSR impairment is recognized in earnings through a valuation allowance for the difference. As the loans are repaid and net servicing revenue is earned, the MSR asset is amortized as an offset to loan servicing income. Servicing revenues are expected to exceed this amortization expense. However, if actual prepayment experience or defaults exceed what was originally anticipated, net servicing revenues may be less than expected and mortgage servicing income may be negative. Income Taxes The Company and its subsidiaries file income tax returns in the U.S. federal jurisdiction, the Commonwealth of Massachusetts, the state of New Hampshire, the state of Maine, and other states as required. For the tax year ended December 31, 2022, the Company expects to file taxes in Massachusetts, New Hampshire, and Maine. Income taxes are accounted for under the asset and liability method. 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 are adjusted through income tax expenses in the period of enactment. Deferred tax assets are reviewed quarterly and reduced by a valuation allowance if, based upon the information available, it is more likely than not that some or all of the deferred tax assets will not be realized. Interest and penalties related to unrecognized tax benefits, if incurred, are recognized as a component of income tax expense. Wealth Management Fee Revenue The Company earns wealth management fees for providing investment management, trust administration, and financial planning services to clients. The Company’s performance obligation under these contracts is satisfied over time as the wealth management services are provided. Fees are recognized monthly based on the monthly value of the assets under management and the applicable fee rate, or at a fixed annual rate, depending on the terms of the contract. No performance-based incentives are earned on wealth management contracts. The Company also earns trust fees for servicing as trustee for certain clients. As trustee, the Company serves as a fiduciary, administers the client’s trust, and in some cases, manages the assets of the trust. The Company’s performance obligation under these agreements is satisfied over time as the administrative and management services are provided. Fees are recognized monthly based on a percentage of the market value of the account or at a fixed annual rate as outlined in the agreement. The Company also earns fees for trust related activities. The Company’s performance obligation under these agreements is satisfied at a point in time and recognized when these services have been performed. Other Banking Fee Income The Company charges a variety of fees to its clients for services provided on the deposit and deposit management related accounts. Each fee is either transaction-based or assessed monthly. The types of fees include service charges on accounts, wire transfer fees, maintenance fees, ATM fee charges, and other miscellaneous charges related to the accounts. These fees are not governed by individual contracts with clients. They are charged to clients based on disclosures presented to these clients upon opening these accounts, along with updated disclosures when changes are made to the fee structures. The transaction-based fees are recognized in revenue when charged to the client based on specific activity on the client’s account. Monthly service and maintenance charges are recognized in the month they are earned and are charged directly to the client’s account. Pension and Retirement Plans The Company sponsors a defined benefit pension plan (the “Pension Plan”) and a postretirement health care plan covering substantially all employees hired before May 2, 2011. Effective December 31, 2017, the accrual of benefits for all participants in the Pension Plan was frozen. Benefits for the postretirement health care plan are based on years of service. Expenses for the postretirement health care plan are recognized over the employee’s service life utilizing the projected unit credit actuarial cost method. Effective November 7, 2019, the postretirement health care plan was frozen for employees hired after that date. The Company also sponsors non-qualified retirement programs that provide supplemental retirement benefits to certain current and former executives. Prior to 2016, the Company provided individual non-qualified defined benefit supplemental executive retirement plans (“DB SERPs”) to certain executives. The DB SERPs generally provide for an annual benefit payable in equal monthly installments following the executive’s retirement and continuing for at least the remainder of his or her lifetime, with such annual benefit generally based on the executive’s years of service and his or her highest three consecutive years of base salary and bonus. In 2016, the Company’s Board of Directors discontinued the use of DB SERPs for new entrants to the Company’s non-qualified retirement programs. Instead, new entrants are provided with individual non-qualified defined contribution supplemental executive retirement plans (“DC SERPs”). Under the DC SERPs, the Company may contribute an amount equal to 10 % of the executive’s base salary and bonus to his or her account under the Company’s non-qualified deferred compensation plan, the Executive Deferred Compensation Plan. Expense for the DB SERPs is recognized over the executive’s service life utilizing the projected unit credit actuarial cost method. Expense for the DC SERPs is recognized as incurred. The Company maintains a Profit-Sharing Plan (“PSP”) that provides for deferral of federal and state income taxes on employee contributions allowed under Section 401(k) of federal law. The Company matches employee contributions up to 100 % of the first 4 % of each participant’s salary, eligible bonus, and eligible incentive. Each year, the Company may also make a discretionary contribution to the PSP based on eligible salary, bonus, and incentive. Employees are eligible to participate in the PSP on the first day of their initial date of service. Employees are also eligible to participate in the discretionary contribution portion of the PSP on the first date of their initial date of service. The employee must be employed on the last day of the calendar year or retire at the normal retirement age of 65 during the calendar year to receive the discretionary contribution. Share-Based Compensation Share-based compensation plans provide for stock option awards, restricted stock awards, time-based restricted stock units (“RSUs”), and performance-based restricted stock units (“PRSUs”). Compensation expense for restricted stock awards is recognized over the vesting period based on the fair value at the date of grant. RSUs and PRSUs are valued at the fair market value of the Company’s common stock as of the award date. PRSUs’ compensation expense is based on the most recent performance assumption available and is adjusted as assumptions change. If the goals are not met, vesting does not occur, no compensation cost will be recognized and any recognized compensation costs will be reversed. Stock-based awards that do not require future service are expensed in the year of grant. Derivative Instruments and Hedging Activiti

Recently Issued and Adopted Acc

Recently Issued and Adopted Accounting Standards	12 Months Ended
	Dec. 31, 2022
Accounting Standards Update and Change in Accounting Principle [Abstract]
Recently Issued and Adopted Accounting Standards	3. Recently Issued and Adopted Accounting Standards Accounting Pronouncements Adopted in 2022 In December 2022, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2022-06, Reference Rate Reform (Topic 848): Deferral of the Sunset Date of Topic 848. The amendments in this ASU defer the sunset date of Topic 848 from December 31, 2022, to December 31, 2024, after which entities will no longer be permitted to apply the relief in Topic 848. The ASU is effective upon issuance. The FASB had previously issued 2020-04 - Facilitation of the Effects of Reference Rate Reform on Financial Reporting and related amendments in 2020 to ease the potential burden in accounting for reference rate reform. The amendments in ASU 2020-04 were elective and applied to all entities that have contracts, hedging relationships, and other transactions that reference the London Inter-bank Offer Rate (“LIBOR”) or another reference rate expected to be discontinued due to reference rate reform. The adoption of the new ASU did no t have an impact on the Company's consolidated financial statements. Accounting Pronouncements Yet to be Adopted In March 2022, the FASB issued Accounting Standards Update (“ASU”) 2022-02, Financial Instruments – Credit Losses (Topic 326): Troubled Debt Restructurings and Vintage Disclosures. The amendments in this ASU eliminate the accounting guidance for troubled debt restructurings (“TDRs”) by creditors in Subtopic 310-40, Receivables – Troubled Debt Restructurings by Creditors , while enhancing disclosure requirements for certain loan refinancings and restructurings by creditors when a borrower is experiencing financial difficulty. For public business entities, the amendments in this ASU require an entity disclose current-period gross write-offs by year of origination for financing receivables and net investments in leases. This ASU is effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. Early adoption was permitted. The Company plans to adopt this guidance in January of 2023. The adoption of the new ASU is not expected to have an impact on the Company's consolidated financial statements. In March 2022, the FASB issued ASU 2022-01, Derivatives and Hedging (Topic 815): Fair Value Hedging - Portfolio Layer Method . The amendments in this ASU allow multiple hedged layers to be designated for a single closed portfolio of financial assets or one or more beneficial interests secured by a portfolio of financial instruments. The amendments in this ASU also clarify the accounting for and promote consistency in the reporting of hedge basis adjustments applicable to both a single hedged layer and multiple hedged layers. These amendments are effective for fiscal years beginning after December 15, 2022, and interim periods within those fiscal years. The adoption of the new ASU is not expected to have an impact on the Compa ny's consolidated financial statements. As of December 31, 2022, the Company has no hedge relationships designated as fair value hedges.

Mergers

Mergers	12 Months Ended
	Dec. 31, 2022
Business Combinations [Abstract]
Mergers	4. Mergers Northmark Bank On October 1, 2022, the Company completed its merger (the “Northmark Merger”) with Northmark Bank. (“Northmark”), adding three banking offices in Massachusetts. Under the terms of the Agreement and Plan of Merger, each outstanding share of Northmark common stock was converted into 0.9950 shares of the Company’s common stock. As a result of the merger, former Northmark stockholders received an aggregate of 788,137 shares of the Company's common stock. The total consideration paid amounted to $ 62.8 million, based on the closing price of $ 79.74 of the Company's common stock and cash paid for fractional shares on October 1, 2022. The Company recorded total assets of $ 428.7 million, assumed total liabilities of $ 378.5 million, and recorded $ 12.6 million in goodwill. The Company accounted for the merger using the acquisition method pursuant to ASC Topic 805, “Business Combinations.” Accordingly, the Company recorded merger expenses of $ 1.9 million during the year ended at December 31, 2022. Additionally, on October 1, 2022, the Company recorded $ 2.2 million in provision for credit losses to reflect the impact of CECL on the acquired loans. The acquisition method requires the acquirer to recognize the assets acquired and the liabilities assumed at their fair values as of the acquisition date. The following table summarizes the estimated fair value of the assets acquired and liabilities assumed as of the date of the acquisition: At October 1, 2022 Net Assets Acquired at Fair Value (dollars in thousands) Total Purchase Price $ 62,850 Assets Cash and cash equivalents $ 82,174 Investments 22,929 Gross loans 303,215 Allowance for loan loss — Premises and equipment 6,856 Core deposit intangible 5,320 Other assets 8,181 Total assets acquired 428,675 Liabilities Deposits 373,129 Repurchase agreements 3,745 Other liabilities 1,579 Total liabilities assumed 378,453 Net assets acquired $ 50,222 Goodwill $ 12,628 Fair value adjustments to assets acquired and liabilities assumed are generally amortized using either an effective yield or straight-line basis over periods consistent with the average life, useful life, and/or contractual term of the related assets and liabilities. Fair values of the major categories of assets acquired and liabilities assumed were determined as follows: Cash and Cash Equivalents The fair values of cash and cash equivalents approximate the respective carrying amounts because the instruments are payable on demand or have short-term maturities. Investments The fair values of securities were based on quoted market prices for identical securities received from an independent, nationally recognized, third-party pricing service. Prices provided by the independent pricing service were based on recent trading activity and other observable information including, but not limited to, market interest rate curves, referenced credit spreads, and estimated prepayment rates where applicable. Loans Fair value was determined using market participant assumptions in estimating the amount and timing of both principal and interest cash flows expected to be collected, as adjusted for an estimate of default rate and prepayments, and then applying a market-based discount rate to those cash flows. Premises and Equipment The fair value of premises was determined based upon appraisals by licensed real estate appraisers. The appraisal was based upon the best and highest use of the property with the final value determined based upon an analysis of the cost, sales comparison, and income capitalization approaches for the property appraised. Core Deposit Intangible The fair value of the core deposit intangible is derived by comparing the interest rate and servicing costs that the financial institution pays on the core deposit liability versus the current market rate for alternative sources of financing, while factoring in estimates over the remaining life and attrition rate of the deposit accounts. The intangible asset represents the stable and relatively low cost source of funds that the deposits and accompanying relationships provide the Company, when compared to alternative funding sources. Deposits The fair value of acquired savings and transaction deposit accounts was assumed to approximate the carrying value as these accounts have no stated maturity and are payable on demand. The fair value of time deposits was determined based on the present value of the contractual cash flows over the remaining period to maturity using a market interest rate. Selected Pro Forma Results The following summarizes the pro forma results of operations as if the Company merged with Northmark on January 1, 2022 (2021 amounts represent combined results for the Company and Northmark). The selected pro forma financial information is presented for illustrative purposes only and is not necessarily indicative of the financial results of the combined companies had the acquisition actually been completed at the beginning of the periods presented, nor does it indicate future results for any other interim or full-year period. For the Year Ended December 31, 2022 2021 (dollars in thousands) Net interest and dividend income after provision for loan losses $ 169,606 $ 111,753 Net Income 69,839 29,182 Excluded from the pro forma results of operations for the year ended December 31, 2022 are merger-related costs of approximately $ 1.9 million recognized by the Company. There were no merger related expenses for the year ended December 31, 2021. These costs primarily consisted of contract terminations arising due to the merger, the acceleration of certain compensation and benefit costs, and other merger expenses. The provision for credit losses recorded on acquired loans of $ 2.2 million was also excluded as a non-recurring adjustment. Wellesley Bancorp, Inc. The Company completed its merger (the “Wellesley Merger”) with Wellesley Bancorp, Inc. (“Wellesley”) on June 1, 2020. Under the terms of the Agreement and Plan of Merger, each outstanding share of Wellesley common stock was converted into 0.580 shares of the Company’s common stock. As a result of the merger, former Wellesley stockholders received an aggregate of 1,502,814 shares of the Company’s common stock. The total consideration paid amounted to $ 88.8 million, based on the closing price of $ 58.00 of the Company's common stock, the value of Wellesley's exercisable options, and cash paid for fractional shares. The Company accounted for the merger using the acquisition method and recorded total assets of $ 985.6 million, including $ 20.7 million in goodwill, and assumed total liabilities of $ 917.6 million.

Cash and Cash Equivalents

Cash and Cash Equivalents	12 Months Ended
	Dec. 31, 2022
Cash and Cash Equivalents [Abstract]
Cash and Cash Equivalents	5. CASH AND CASH EQUIVALENTS At December 31, 2022 and December 31, 2021, cash and due from banks totaled $ 30.7 million and $ 180.2 million , respectively. There were no amounts required to be maintained at the Federal Reserve Bank of Boston (“FRB of Boston”) at December 31, 2022 and December 31, 2021. At December 31, 2022 and December 31, 2021 , the Company pledged $ 500,000 to the New Hampshire Banking Department relating to Cambridge Trust Company of New Hampshire, Inc.’s operations in that state. The Company did no t have any cash pledged as collateral to derivative counterparties at December 31, 2022 , as compared to $ 13.3 million at December 31, 2021. See Note 21 - Derivatives and Hedging Activities for a discussion of the Company’s derivative and hedging activities .

Investment Securities

Investment Securities	12 Months Ended
	Dec. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Investment Securities	6. INVESTMENT SECURITIES Investment securities have been classified in the accompanying consolidated balance sheets according to management’s intent. The carrying amounts of securities and their approximate fair values were as follows: December 31, 2022 December 31, 2021 Amortized Gross Gross Fair Amortized Gross Gross Fair (dollars in thousands) Available for sale securities U.S. Government Sponsored $ 22,997 $ — $ ( 3,264 ) $ 19,733 $ 22,996 $ 246 $ ( 231 ) $ 23,011 Mortgage-backed securities 158,034 3 ( 25,354 ) 132,683 176,531 959 ( 4,462 ) 173,028 Corporate debt securities 996 4 — 1,000 1,743 24 ( 3 ) 1,764 Total available for sale securities $ 182,027 $ 7 $ ( 28,618 ) $ 153,416 $ 201,270 $ 1,229 $ ( 4,696 ) $ 197,803 Held to maturity securities U.S. Treasury Notes $ 3,970 $ — $ ( 18 ) $ 3,952 $ — $ — $ — $ — Mortgage-backed securities 951,372 4 ( 157,208 ) 794,168 864,983 3,981 ( 13,258 ) 855,706 Corporate debt securities 250 — ( 6 ) 244 6,997 26 — 7,023 Municipal securities 96,405 88 ( 9,271 ) 87,222 105,081 3,798 ( 516 ) 108,363 Total held to maturity securities $ 1,051,997 $ 92 $ ( 166,503 ) $ 885,586 $ 977,061 $ 7,805 $ ( 13,774 ) $ 971,092 Total $ 1,234,024 $ 99 $ ( 195,121 ) $ 1,039,002 $ 1,178,331 $ 9,034 $ ( 18,470 ) $ 1,168,895 All of the Company’s mortgage-backed securities have been issued by, or are collateralized by securities issued by, either the Government National Mortgage Association (“Ginnie Mae” or “GNMA”), the Federal National Mortgage Association (“Fannie Mae” or “FNMA”), or the Federal Home Loan Mortgage Corporation (“Freddie Mac” or “FHLMC”). The amortized cost and fair value of investment securities, aggregated by the contractual maturity, are shown below. Municipal securities are aggregated by the earliest of call date or contractual maturity. Maturities of mortgage-backed securities do not take into consideration scheduled amortization or prepayments. Actual maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties. December 31, 2022 Within One Year After One, But After Five, But After Ten Years Total Amortized Fair Amortized Fair Amortized Fair Amortized Fair Amortized Fair (dollars in thousands) Available for sale securities U.S. Government Sponsored Enterprise obligations $ — $ — $ 9,997 $ 9,012 $ 5,000 $ 4,346 $ 8,000 $ 6,375 $ 22,997 $ 19,733 Mortgage-backed securities — — 10,680 9,966 41,622 34,934 105,732 87,783 158,034 132,683 Corporate debt securities 996 1,000 — — — — — — 996 1,000 Total available for sale securities $ 996 $ 1,000 $ 20,677 $ 18,978 $ 46,622 $ 39,280 $ 113,732 $ 94,158 $ 182,027 $ 153,416 Held to maturity securities U.S. Treasury Notes $ 987 $ 983 $ 2,983 $ 2,969 $ — $ — $ — $ — $ 3,970 $ 3,952 Mortgage-backed securities — — 19,572 18,355 48,731 42,866 883,069 732,947 951,372 794,168 Corporate debt securities — — 250 244 — — — — 250 244 Municipal securities 6,987 6,997 18,657 18,602 26,441 26,028 44,320 35,595 96,405 87,222 Total held to maturity securities $ 7,974 $ 7,980 $ 41,462 $ 40,170 $ 75,172 $ 68,894 $ 927,389 $ 768,542 $ 1,051,997 $ 885,586 Total $ 8,970 $ 8,980 $ 62,139 $ 59,148 $ 121,794 $ 108,174 $ 1,041,121 $ 862,700 $ 1,234,024 $ 1,039,002 The following tables show the Company’s investment securities with gross unrealized losses, for which an allowance for credit losses has not been recorded at December 31, 2022 or at December 31, 2021, aggregated by investment category and length of time that individual investment securities have been in a continuous loss position: December 31, 2022 Less than 12 months 12 months or longer Total Fair Unrealized Fair Unrealized Fair Unrealized (dollars in thousands) Available for sale securities U.S. Government Sponsored Enterprise $ 10,722 $ ( 2,278 ) $ 9,012 $ ( 986 ) $ 19,734 $ ( 3,264 ) Mortgage-backed securities 41,832 ( 3,097 ) 90,545 ( 22,257 ) 132,377 ( 25,354 ) Total available for sale securities $ 52,554 $ ( 5,375 ) $ 99,557 $ ( 23,243 ) $ 152,111 $ ( 28,618 ) Held to maturity securities U.S. Treasury Notes $ 3,952 $ ( 18 ) $ — $ — $ 3,952 $ ( 18 ) Mortgage-backed securities 230,708 ( 22,362 ) 562,835 ( 134,846 ) 793,543 ( 157,208 ) Corporate debt securities 243 ( 6 ) — — 243 ( 6 ) Municipal securities 51,969 ( 4,388 ) 13,714 ( 4,883 ) 65,683 ( 9,271 ) Total held to maturity securities $ 286,872 $ ( 26,774 ) $ 576,549 $ ( 139,729 ) $ 863,421 $ ( 166,503 ) Total $ 339,426 $ ( 32,149 ) $ 676,106 $ ( 162,972 ) $ 1,015,532 $ ( 195,121 ) December 31, 2021 Less than 12 months 12 months or longer Total Fair Unrealized Fair Unrealized Fair Unrealized (dollars in thousands) Available for sale securities U.S. Government Sponsored Enterprise $ 4,881 $ ( 115 ) $ 4,884 $ ( 116 ) $ 9,765 $ ( 231 ) Mortgage-backed securities 74,724 ( 2,253 ) 47,871 ( 2,209 ) 122,595 ( 4,462 ) Corporate debt securities 760 ( 3 ) — — 760 ( 3 ) Total available for sale securities $ 80,365 $ ( 2,371 ) $ 52,755 $ ( 2,325 ) $ 133,120 $ ( 4,696 ) Held to maturity securities Mortgage-backed securities $ 740,966 $ ( 12,509 ) $ 15,345 $ ( 749 ) $ 756,311 $ ( 13,258 ) Municipal securities 12,607 ( 194 ) 5,716 ( 322 ) 18,323 ( 516 ) Total held to maturity securities $ 753,573 $ ( 12,703 ) $ 21,061 $ ( 1,071 ) $ 774,634 $ ( 13,774 ) Total $ 833,938 $ ( 15,074 ) $ 73,816 $ ( 3,396 ) $ 907,754 $ ( 18,470 ) As of December 31, 2022 , 432 debt securities had gross unrealized losses, with an aggregate depreciation of 16.1 % from the Company’s amortized cost basis. The largest unrealized dollar loss of any single security was $ 2.0 million, or 21.5 % of its amortized cost. The largest unrealized loss percentage of any single security was 35.0 % of its amortized cost, or $ 823,000 . The Company believes that the nature and duration of unrealized losses on its debt security positions are primarily a function of interest rate movements and changes in investment spreads and does not consider full repayment of principal on the reported debt obligations to be at risk. Since nearly all of these securities are rated “investment grade” and (a) the Company does not intend to sell these securities before recovery and (b) it is more likely than not that the Company will not be required to sell these securities before recovery, the Company does not expect to suffer a credit loss as of December 31, 2022. U.S. Government obligations with an amortized cost of $ 9.1 million and a fair value of $ 8.0 million were pledged as collateral for repurchase agreements at December 31, 2022. There were no investment securities pledged as collateral for repurchase agreements at December 31, 2021. The following table sets forth information regarding sales of investment securities and the resulting gains or losses from such sales: For the Year Ended December 31, 2022 2021 2020 (dollars in thousands) Amortized cost of securities sold $ 19,018 $ — $ 10,752 Gross gains realized on securities sold — — 111 Gross losses realized on securities sold — — ( 42 ) Net proceeds from securities sold $ 19,018 $ — $ 10,821 The Company monitors the credit quality of certain debt securities through the use of credit rating among other factors on a quarterly basis. Credit ratings are opinions about the credit quality of a security and are utilized by the Company to make informed decisions. Investment grade securities are rated BBB-/Baa3 or higher and are generally considered to be of low risk. At December 31, 2022 and 2021 respectively, the Company’s debt securities portfolio did not contain any securities below investment grade, as reported by major credit rating agencies. At December 31, 2022 and 2021, respectively, none of the Company's investment securities were delinquent or in non-accrual status . The following tables summarize the credit rating of the Company’s debt securities portfolio at December 31, 2022 and December 31, 2021. December 31, 2022 Mortgage-backed Securities (1) Corporate Debt Securities Municipal Securities U.S. GSE Obligations U.S. Treasury Notes Total (dollars in thousands) Available for sale securities, at fair value AAA/AA/A $ 132,683 $ — $ — $ 19,733 $ — $ 152,416 BBB/BB/B — 1,000 — — — 1,000 Total available for sale securities $ 132,683 $ 1,000 $ — $ 19,733 $ — $ 153,416 Held to maturity securities, at amortized cost AAA/AA/A $ 951,372 $ 250 $ 96,405 $ — $ 3,970 $ 1,051,997 Total held to maturity securities $ 951,372 $ 250 $ 96,405 $ — $ 3,970 $ 1,051,997 December 31, 2021 Mortgage-backed Securities (1) Corporate Debt Securities Municipal Securities U.S. GSE Obligations Total (dollars in thousands) Available for sale securities, at fair value AAA/AA/A $ 173,028 $ 759 $ — $ 23,011 $ 196,798 BBB/BB/B — 1,005 — — 1,005 Total available for sale securities $ 173,028 $ 1,764 $ — $ 23,011 $ 197,803 Held to maturity securities, at amortized cost AAA/AA/A $ 864,983 $ 6,997 $ 105,081 $ — $ 977,061 Total held to maturity securities $ 864,983 $ 6,997 $ 105,081 $ — $ 977,061 Includes Agency mortgage-backed pass-through securities and collateralized mortgage obligations issued by U.S. Government Sponsored enterprises ("GSEs") and U.S. government agencies, such as FNMA, FHLMC, and GNMA that are not rated by Moody’s or Standard & Poor's. Each security contains a guarantee by the issuing GSE or agency and therefore carries an implicit guarantee of the U.S. government. These have been categorized as AAA/AA/A.

Loans and Allowance for Credit

Loans and Allowance for Credit Losses	12 Months Ended
	Dec. 31, 2022
Receivables [Abstract]
Loans and Allowance for Credit Losses	7. LOANS AND ALLOWANCE FOR CREDIT LOSSES Loans outstanding are detailed by category as follows: December 31, 2022 December 31, 2021 (dollars in thousands) Residential mortgage Mortgages - fixed rate $ 902,968 $ 716,456 Mortgages - adjustable rate 703,958 679,675 Construction 35,299 13,012 Deferred costs, net of unearned fees 6,613 5,936 Total residential mortgages 1,648,838 1,415,079 Commercial mortgage Mortgages - non-owner occupied 1,592,732 1,272,135 Mortgages - owner occupied 183,591 150,632 Construction 135,782 86,246 Deferred costs, net of unearned fees 2,318 1,989 Total commercial mortgages 1,914,423 1,511,002 Home equity Home equity - lines of credit 108,961 85,639 Home equity - term loans 2,098 2,017 Deferred costs, net of unearned fees 292 304 Total home equity 111,351 87,960 Commercial and industrial Commercial and industrial 349,026 247,024 PPP loans 1,384 22,856 Unearned fees, net of deferred costs 240 ( 434 ) Total commercial and industrial 350,650 269,446 Consumer Secured 35,679 34,308 Unsecured 1,897 1,303 Deferred costs, net of unearned fees 18 8 Total consumer 37,594 35,619 Total loans $ 4,062,856 $ 3,319,106 The Coronavirus Aid, Relief, and Economic Security Act, (the “CARES Act”), was signed into law on March 27, 2020, and provided emergency economic relief to individuals and businesses impacted by the COVID-19 pandemic. Among other things, the CARES Act authorized the Small Business Administration (“SBA”) to temporarily guarantee loans under a new 7(a) loan program called the Paycheck Protection Program (“PPP”). As a qualified SBA lender, the Company was authorized to originate PPP loans. PPP loans have: (a) an interest rate of 1.0%, (b) a two year or five-year loan term to maturity; and (c) principal and interest payments deferred until the SBA remits the forgiven amount to the Company or 10 months from the end of the covered period, as defined. The SBA will guarantee 100% of the PPP loans made to eligible borrowers. The entire principal amount of the borrower’s PPP loan, including any accrued interest, is eligible to be reduced by the loan forgiveness amount under the PPP so long as employee and compensation levels of the business are maintained and 60% of the loan proceeds are used for payroll expense, with the remaining 40% of the loan proceeds used for other qualifying expenses. The Company did not record a provision for credit losses for PPP loans in 2022, 2021 or 2020 due to the SBA guarantee. Directors and officers of the Company and their associates are clients of, and have other transactions with, the Company in the normal course of business. All loans and commitments included in such transactions were made on substantially the same terms, including interest rates and collateral, as those prevailing at the time for comparable transactions with other persons and do not involve more than normal risk of collection or present other unfavorable features. Asset Quality The Company’s philosophy toward managing its loan portfolios is predicated upon careful monitoring, which stresses early detection and response to delinquent and default situations. The Company seeks to make arrangements to resolve any delinquent or default situation over the shortest possible time frame. As a general rule, loans more than 90 days past due with respect to principal or interest are classified as non-accrual loans. The Company may use discretion regarding other loans over 90 days past due if the loan is well secured and/or in process of collection. The following tables set forth information regarding non-performing loans disaggregated by loan category: December 31, 2022 Residential Commercial Home Commercial and Total (dollars in thousands) Non-performing loans: Non-accrual loans $ 4,733 $ 311 $ 722 $ 73 $ 5,839 Troubled debt restructurings 622 — — 81 703 Total $ 5,355 $ 311 $ 722 $ 154 $ 6,542 December 31, 2021 Residential Commercial Home Commercial and Total (dollars in thousands) Non-performing loans: Non-accrual loans $ 3,777 $ 517 $ 223 $ 111 $ 4,628 Troubled debt restructurings 652 — — 106 758 Total $ 4,429 $ 517 $ 223 $ 217 $ 5,386 It is the Company’s policy to reverse any accrued interest when a loan is put on non-accrual status; as such, the Company did no t record any interest income on non-accrual loans during the years ended December 31, 2022 and December 31, 2021. There were no significant commitments to lend additional funds to borrowers whose loans were on non-accrual status at December 31, 2022 and December 31, 2021. Troubled Debt Restructurings (“TDRs”) Loans are considered restructured in a troubled debt restructuring when the Company has granted concessions to a borrower due to the borrower’s financial condition that it otherwise would not have considered. These concessions may include modifications of the terms of the debt such as deferral of payments, extension of maturity, reduction of principal balance, reduction of the stated interest rate other than normal market rate adjustments, or a combination of these concessions. Debt may be bifurcated with separate terms for each tranche of the restructured debt. Restructuring a loan in lieu of aggressively enforcing the collection of the loan may benefit the Company by increasing the ultimate probability of collection. Restructured loans are classified as accruing or non-accruing based on management’s assessment of the collectability of the loan. Loans which are already on non-accrual status at the time of the restructuring generally remain on non-accrual status for approximately six months or longer before management considers such loans for return to accruing status. Accruing restructured loans are placed into non-accrual status if and when the borrower fails to comply with the restructured terms and management deems it unlikely that the borrower will return to a status of compliance in the near term. TDRs are individually evaluated for credit losses. There were no new TDRs during the years ended December 31, 2022 or December 31, 2021. At December 31, 2022 , four loans were TDRs with a total carrying value of $ 704,000 . There were no TDR defaults during the year ended December 31, 2022. As of December 31, 2021 , four loans were TDRs with a total carrying value of $ 758,000 . There were no TDR defaults during the year ended December 31, 2021. The allowance for credit losses includes a specific reserve for TDRs of approximately $ 60,000 and $ 85,000 as of December 31, 2022 and December 31, 2021, respectively. As of December 31, 2022 and December 31, 2021 , there were no significant commitments to lend additional funds to borrowers whose loans were restructured. Pursuant to Section 4013 of the CARES Act, financial institutions could suspend the requirements under U.S. GAAP related to TDRs for modifications made before December 31, 2020 to loans that were current as of December 31, 2019. As a result of the enactment of the Consolidated Appropriations Act, 2021, in January 2021, the suspension of TDR accounting was extended to, and expired on January 1, 2022. The requirement that a loan be not more than 30 days past due as of December 31, 2019 was still applicable. In response to the COVID-19 pandemic and its economic impact to clients, a short-term modification program that complied with the CARES Act was implemented to provide temporary payment relief to those borrowers directly impacted by COVID-19. The deferred payments along with interest accrued during the deferral period are due and payable on the maturity date. Under issued guidance, provided that these loans were current as of either year end or the date of the modification, these loans were not considered TDR loans at December 31, 2022 and will not be reported as past due during the deferral period. The Company had no loans in deferral as of December 31, 2022. Loans by Credit Quality Indicator. The following tables contain period-end balances of loans receivable disaggregated by credit quality indicator: Credit Quality Indicator - by Origination Year as of December 31, 2022 2022 2021 2020 2019 2018 Prior Revolving loans amortized cost basis Total (dollars in thousands) Residential Mortgage: Current $ 314,599 $ 511,217 $ 276,698 $ 113,251 $ 77,620 $ 350,098 $ — $ 1,643,483 Non-performing — — 206 315 684 4,150 — 5,355 Total $ 314,599 $ 511,217 $ 276,904 $ 113,566 $ 78,304 $ 354,248 $ — $ 1,648,838 Home equity: Current $ 3,611 $ — $ — $ 58 $ 360 $ 481 $ 106,119 $ 110,629 Non-performing — — — — — — 722 722 Total $ 3,611 $ — $ — $ 58 $ 360 $ 481 $ 106,841 $ 111,351 Consumer: Current $ 13,214 $ 8,482 $ 5,353 $ 444 $ 2,078 $ 7,424 $ 599 $ 37,594 Non-performing — — — — — — — — Total $ 13,214 $ 8,482 $ 5,353 $ 444 $ 2,078 $ 7,424 $ 599 $ 37,594 Credit Quality Indicator - by Origination Year as of December 31, 2022 2022 2021 2020 2019 2018 Prior Revolving loans amortized cost basis Total (dollars in thousands) Commercial Mortgage: Credit risk profile by internally 1-6 (Pass) $ 411,927 $ 330,593 $ 222,073 $ 260,588 $ 125,398 $ 489,564 $ — $ 1,840,143 7 (Special Mention) — — 4,562 41,578 21,697 6,132 — 73,969 8 (Substandard) — — — — — 311 — 311 9 (Doubtful) — — — — — — — — 10 (Loss) — — — — — — — — Total $ 411,927 $ 330,593 $ 226,635 $ 302,166 $ 147,095 $ 496,007 $ — $ 1,914,423 Commercial and Industrial: Credit risk profile by internally 1-6 (Pass) $ 128,301 $ 67,727 $ 62,025 $ 28,557 $ 18,794 $ 36,836 $ 475 $ 342,715 7 (Special Mention) — 4,211 130 161 407 121 10 5,040 8 (Substandard) — — 628 2,102 81 84 — 2,895 9 (Doubtful) — — — — — — — — 10 (Loss) — — — — — — — — Total $ 128,301 $ 71,938 $ 62,783 $ 30,820 $ 19,282 $ 37,041 $ 485 $ 350,650 Credit Quality Indicator - by Origination Year as of December 31, 2021 2021 2020 2019 2018 2017 Prior Revolving loans amortized cost basis Total (dollars in thousands) Residential Mortgage: Current $ 535,071 $ 329,501 $ 135,139 $ 101,108 $ 77,702 $ 232,129 $ — $ 1,410,650 Non-performing — 151 — 330 54 3,894 — 4,429 Total $ 535,071 $ 329,652 $ 135,139 $ 101,438 $ 77,756 $ 236,023 $ — $ 1,415,079 Home equity: Current $ — $ 719 $ 3,088 $ 4,469 $ 5,060 $ 5,475 $ 68,926 $ 87,737 Non-performing — — 223 — — — — 223 Total $ — $ 719 $ 3,311 $ 4,469 $ 5,060 $ 5,475 $ 68,926 $ 87,960 Consumer: Current $ 14,427 $ 8,758 $ 1,544 $ 3,168 $ 1,838 $ 5,357 $ 527 $ 35,619 Non-performing — — — — — — — — Total $ 14,427 $ 8,758 $ 1,544 $ 3,168 $ 1,838 $ 5,357 $ 527 $ 35,619 Credit Quality Indicator - by Origination Year as of December 31, 2021 2021 2020 2019 2018 2017 Prior Revolving loans amortized cost basis Total (dollars in thousands) Commercial Mortgage: Credit risk profile by internally 1-6 (Pass) $ 319,633 $ 248,691 $ 320,189 $ 158,462 $ 93,016 $ 298,791 $ — $ 1,438,782 7 (Special Mention) — 1,096 40,879 22,471 2,913 4,131 — 71,490 8 (Substandard) — — — — — 730 — 730 9 (Doubtful) — — — — — — — — 10 (Loss) — — — — — — — — Total $ 319,633 $ 249,787 $ 361,068 $ 180,933 $ 95,929 $ 303,652 $ — $ 1,511,002 Commercial and Industrial: Credit risk profile by internally 1-6 (Pass) $ 83,614 $ 77,073 $ 38,299 $ 34,360 $ 19,727 $ 4,622 $ 353 $ 258,048 7 (Special Mention) 318 350 5,523 406 161 859 10 7,627 8 (Substandard) — 792 2,331 504 — 144 — 3,771 9 (Doubtful) — — — — — — — — 10 (Loss) — — — — — — — — Total $ 83,932 $ 78,215 $ 46,153 $ 35,270 $ 19,888 $ 5,625 $ 363 $ 269,446 With respect to residential real estate mortgages, home equity, and consumer loans, the Company utilizes the following categories as indicators of credit quality: • Performing – These loans are accruing and are considered having low to moderate risk. • Non-performing – These loans are on non-accrual or are past due more than 90 days but are still accruing or are restructured. These loans may contain greater than average risk. With respect to commercial mortgages and commercial loans, the Company utilizes a 10-grade internal loan rating system as an indicator of credit quality. The grades are as follows: • Loans rated 1-6 (Pass) – These loans are considered “pass” rated with low to moderate risk. • Loans rated 7 (Special Mention) – These loans have potential weaknesses warranting close attention, which, if left uncorrected, may result in deterioration of the credit at some future date. • Loans rated 8 (Substandard) – These loans have well-defined weaknesses that jeopardize the orderly liquidation of the debt under the original loan terms. Loss potential exists but is not identifiable in any one client. • Loans rated 9 (Doubtful) – These loans have pronounced weaknesses that make full collection highly questionable and improbable. • Loans rated 10 (Loss) – These loans are considered uncollectible and continuance as a bankable asset is not warranted. Delinquencies The past due status of a loan is determined in accordance with its contractual repayment terms. All loan types are reported past due when one scheduled payment is due and unpaid for 30 days or more. Loan delinquencies can be attributed to many factors, such as but not limited to, a continuing weakness in, or deteriorating, economic conditions in the region in which the collateral is located, the loss of a tenant or lower lease rates for commercial borrowers, or the loss of income for consumers and the resulting liquidity impacts on the borrowers. The following tables contain period-end balances of loans receivable disaggregated by past due status: December 31, 2022 30-59 Days 60-89 Days 90 Days or greater Total Past Due Current Loans Total (dollars in thousands) Residential mortgage $ 11,359 $ 1,454 $ 1,809 $ 14,622 $ 1,634,216 $ 1,648,838 Commercial mortgage — — — — 1,914,423 1,914,423 Home equity 962 393 214 1,569 109,782 111,351 Commercial and industrial 65 269 — 334 350,316 350,650 Consumer 81 — — 81 37,513 37,594 Total $ 12,467 $ 2,116 $ 2,023 $ 16,606 $ 4,046,250 $ 4,062,856 December 31, 2021 30-59 Days 60-89 Days 90 Days Total Current Total (dollars in thousands) Residential mortgage $ 8,470 $ 415 $ 1,488 $ 10,373 $ 1,404,706 $ 1,415,079 Commercial mortgage 476 — — 476 1,510,526 1,511,002 Home equity 314 643 — 957 87,003 87,960 Commercial and industrial 5 437 — 442 269,004 269,446 Consumer — — — — 35,619 35,619 Total $ 9,265 $ 1,495 $ 1,488 $ 12,248 $ 3,306,858 $ 3,319,106 There were no loans 90 days or more past due and still accruing at December 31, 2022 or December 31, 2021. Allowance for Credit Losses The following tables contain changes in the allowance for credit losses disaggregated by loan category: For the Year Ended December 31, 2022 Residential Commercial Home Commercial & Consumer Unfunded Commitments Total (dollars in thousands) Allowance for credit loss: Allowance for credit losses - loan Balance at December 31, 2021 $ 13,383 $ 17,133 $ 406 $ 2,989 $ 585 $ — $ 34,496 Provision for acquired loans 527 1,337 117 113 8 — 2,102 Initial allowance for PCD 19 37 — — — — 56 Charge-offs — — — ( 23 ) ( 29 ) — ( 52 ) Recoveries 4 — — 89 12 — 105 Provision for (release of) credit ( 612 ) 579 50 985 65 — 1,067 Allowance for credit losses - loan portfolio $ 13,321 $ 19,086 $ 573 $ 4,153 $ 641 $ — $ 37,774 Allowance for credit losses - Balance at December 31, 2021 $ — $ — $ — $ — $ — $ 1,384 $ 1,384 Acquired loan commitments — — — — — 137 137 Provision for (release of) credit — — — — — 575 575 Allowance for credit losses- $ — $ — $ — $ — $ — $ 2,096 $ 2,096 Total allowance for credit loss $ 13,321 $ 19,086 $ 573 $ 4,153 $ 641 $ 2,096 $ 39,870 For the Year Ended December 31, 2021 Residential Commercial Home Commercial & Consumer Unfunded Commitments Total (dollars in thousands) Allowance for credit loss: Allowance for credit losses - loan portfolio: Balance at December 31, 2020 $ 13,067 $ 18,564 $ 552 $ 3,309 $ 524 $ — $ 36,016 Charge-offs ( 4 ) — — ( 41 ) ( 42 ) — ( 87 ) Recoveries — 30 — 181 30 — 241 Provision for (release of) credit 320 ( 1,461 ) ( 146 ) ( 460 ) 73 — ( 1,674 ) Allowance for credit losses - loan portfolio $ 13,383 $ 17,133 $ 406 $ 2,989 $ 585 $ — $ 34,496 Allowance for credit losses - unfunded commitments: Balance at December 31, 2020 $ — $ — $ — $ — $ — $ 1,004 $ 1,004 Provision for credit — — — — — 380 380 Allowance for credit losses-unfunded commitments — — — — — 1,384 1,384 Total allowance for credit loss $ 13,383 $ 17,133 $ 406 $ 2,989 $ 585 $ 1,384 $ 35,880

Federal Home Loan Bank ("FHLB")

Federal Home Loan Bank ("FHLB") of Boston Stock	12 Months Ended
	Dec. 31, 2022
Federal Home Loan Bank ("FHLB") of Boston
Federal Home Loan Bank ("FHLB") Stock [Line Items]
Federal Home Loan Bank ("FHLB") of Boston Stock	8. FEDERAL HOME LOAN BANK (“FHLB”) OF BOSTON STOCK As a voluntary member of the FHLB of Boston, the Company is required to invest in stock of the FHLB of Boston (which is considered a restricted equity security) in an amount based upon its outstanding advances from the FHLB of Boston. At December 31, 2022 and 2021, the Company’s investment in FHLB of Boston stock totaled $ 6.3 million and $ 4.8 million , respectively. No market exists for shares of this stock. The Company’s cost for FHLB of Boston stock is equal to its par value. Upon redemption of the stock, which is at the discretion of the FHLB of Boston, the Bank would receive an amount equal to the par value of the stock. At its discretion, the FHLB of Boston may also declare dividends on its stock. The Company’s investment in FHLB of Boston stock is reviewed for impairment at each reporting date based on the ultimate recoverability of the cost basis of the stock. As of December 31, 2022 and December 31, 2021, no impairment has been recognized.

Banking Premises and Equipment

Banking Premises and Equipment	12 Months Ended
	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Banking Premises and Equipment	9. BANKING PREMISES AND EQUIPMENT A summary of the cost and accumulated depreciation and amortization of property, leasehold improvements, and equipment is presented below: December 31, Estimated 2022 2021 Useful Lives (dollars in thousands) Land $ 3,396 $ 1,516 Building and leasehold improvements 25,588 20,254 3 - 30 years Equipment, including vaults 20,165 18,592 3 - 20 years Work in process 22 19 Subtotal 49,171 40,381 Accumulated depreciation and amortization ( 25,874 ) ( 23,055 ) Total $ 23,297 $ 17,326 Total depreciation expense for the years ended December 31, 2022, 2021 , and 2020 amounted to $ 2.7 million, $ 2.6 million, and $ 2.5 million, and is included in occupancy and equipment expenses in the accompanying consolidated statements of income.

Intangible Assets

Intangible Assets	12 Months Ended
	Dec. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	10. INTANGIBLE ASSETS Core deposit intangible (“CDI”) . At December 31, 2022 and December 31, 2021, the carrying value of CDI assets totaled $ 7.4 million and $ 2.6 million, respectively. The Company recorded CDI assets of $ 5.3 million associated with the Northmark merger during the year ended December 31, 2022. The Company recorded a mortization expense of CDI assets totaling $ 494,000 , $ 361,000 , and $ 361,000 for the years ended December 31, 2022 , December 31, 2021, and December 31, 2020, respectively. The weighted-average remaining amortization period for CDI was 8.7 years and 7.3 years at December 31, 2022 and December 31, 2021, respectively. Mortgage servicing rights. Periodically, the Company sells certain residential mortgage loans to the secondary market. Generally, these loans are sold without recourse or other credit enhancements. The Company sells loans and either releases or retains the servicing rights. For loans sold with servicing rights retained, the Company provides the servicing for the loans on a per-loan fee basis. Mortgage loans sold with servicing rights retained during the years ended December 31, 2022, December 31, 2021 , and December 31, 2020 were $ 5.8 million, $ 25.3 million, and $ 60.5 million, respectively. The following table provides an analysis of mortgage servicing rights, which are included in other assets: Mortgage Valuation Total (dollars in thousands) Balance at December 31, 2019 $ 1,347 $ ( 26 ) $ 1,321 Mortgage servicing rights acquired as a result of the Wellesley merger 50 — 50 Mortgage servicing rights capitalized 536 — 536 Amortization charged against servicing income ( 572 ) — ( 572 ) Change in impairment reserve — ( 116 ) ( 116 ) Balance at December 31, 2020 $ 1,361 $ ( 142 ) $ 1,219 Balance at December 31, 2020 $ 1,361 $ ( 142 ) $ 1,219 Mortgage servicing rights capitalized 281 — 281 Amortization charged against servicing income ( 559 ) — ( 559 ) Change in impairment reserve — 142 142 Balance at December 31, 2021 $ 1,083 $ — $ 1,083 Balance at December 31, 2021 $ 1,083 $ — $ 1,083 Mortgage servicing rights acquired as a result of the Northmark merger 785 785 Mortgage servicing rights capitalized 71 — 71 Amortization charged against servicing income ( 274 ) — ( 274 ) Change in impairment reserve — — — Balance at December 31, 2022 $ 1,665 $ — $ 1,665 The fair value of the Company’s mortgage servicing rights portfolio was $ 2.3 million and $ 1.5 million as of December 31, 2022 and 2021, respectively. The fair value of mortgage servicing rights is estimated based on the present value of expected cash flows, incorporating assumptions for discount rate, prepayment speed, and servicing cost. The weighted-average amortization period for mortgage servicing rights portfolio was 7.1 years and 5.7 years at December 31, 2022 and 2021, respectively. The estimated aggregate future amortization expense for mortgage servicing rights for each of the next five years and thereafter is as follows: Future Amortization Expense (dollars in thousands) 2023 $ 217 2024 192 2025 170 2026 150 2027 132 Thereafter 804 Total $ 1,665

Deposits

Deposits	12 Months Ended
	Dec. 31, 2022
Deposits [Abstract]
Deposit	11. DEPOSITS Deposits are summarized as follows: December 31, 2022 December 31, 2021 (dollars in thousands) Demand deposits (non-interest bearing) $ 1,366,395 $ 1,393,935 Interest bearing checking 908,961 763,188 Money market 1,162,773 1,104,238 Savings 790,628 907,722 Retail certificates of deposit under $250,000 117,532 99,196 Retail certificates of deposit $250,000 or greater 87,528 60,171 Brokered certificates of deposit 381,559 2,702 Total deposits $ 4,815,376 $ 4,331,152 Certificates of deposit had the following schedule of maturities: December 31, 2022 December 31, 2021 (dollars in thousands) 2022 $ — $ 132,212 2023 533,513 19,062 2024 39,753 4,443 2025 5,377 2,182 2026 6,021 4,170 2027 and after 1,955 — Total certificates of deposit $ 586,619 $ 162,069 Related Party Deposits Deposit accounts of directors, executive officers, and their respective affiliates tot aled $ 2.7 million an d $ 7.5 million as of December 31, 2022 and 2021 , respectively.

Borrowings

Borrowings	12 Months Ended
	Dec. 31, 2022
Debt Disclosure [Abstract]
Borrowings	12. BORROWINGS Federal Home Loan Bank Advances At December 31, 2022 the Company had $ 100.0 million of short-term advances from the FHLB of Boston, with a weighted average rate of 4.38 %. At December 31, 2021 , the Company did no t have any short-term advances outstanding from the FHLB of Boston. Information relating to long-term borrowings from the FHLB of Boston is presented below: December 31, 2022 December 31, 2021 Amount Rate Amount Rate Stated Maturity (dollars in thousands) 2022 $ — — $ 221 1.84 % 2023* 176 2.36 16,221 3.69 $ 176 2.36 % $ 16,442 3.67 % * December 31, 2021 totals includes a $ 15 million advance with an interest rate of 3.80 %, that was callable by the FHLB of Boston on January 27, 2022 . Securities Sold Under Agreements to Repurchase The Company periodically enters into repurchase agreements with its larger deposit and commercial clients as part of its cash management services which are typically overnight borrowings. Repurchase agreements with clients totaled $ 5.0 million as of December 31, 2022. The daily average balance of securities sold under agreements to repurchase during the year ended December 31, 2022 was $ 1.2 million. There were no repurchase agreements with clients outstanding as of December 31, 2021. The Company retains control of the securities underlying these agreements. Federal Reserve Bank PPP Loan Facility (“PPPLF”) Advances During the years ended December 31, 2022 and December 31, 2021, the Company did no t borrow funds from the Federal Reserve Bank’s PPPLF. During the year ended December 31, 2020, in order to fund a portion of the Company’s PPP loan originations, the Company borrowed $ 85.4 million from the Federal Reserve Bank’s PPPLF, which carried a rate of 0.35 % fixed for the term of the corresponding PPP loan. The Company pledged eligible PPP loans as collateral for the borrowings. As of December 31, 2020, all of the Company’s borrowings under the PPPLF were repaid. Subordinated Debt In the fourth quarter of 2020, the Company redeemed $ 10.0 million in subordinated debt, bearing a 6.0 % coupon, which was assumed as part of the Wellesley Merger. Unused Borrowing Capacity with the FHLB of Boston and FRB of Boston All short- and long-term borrowings with the FHLB of Boston are secured by the Company’s stock in the FHLB of Boston and a blanket lien on “qualified collateral” defined principally as 60 % - 70 % of the carrying value of certain residential mortgage loans. Based upon collateral pledged, the Bank’s unused borrowing capacity with the FHLB of Boston at December 31, 2022 was approximately $ 639.0 million. The Company also has a line of credit with the FRB of Boston. The Banks did no t have any outstanding FRB borrowings as of December 31, 2022 and 2021. At December 31, 2022 and 2021 , the Company had pledged investment securities, CRE, and C&I loans with aggregate principal balances of approximately $ 970.1 million and $ 652.3 million, respectively, as collateral for this line of credit. Based upon the collateral pledged, the Company’s unused borrowing capacity with the FRB of Boston at December 31, 2022 and 2021 was approximately $ 680.4 million and $ 419.6 million, respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Income Taxes	13. INCOME TAXES The components of income tax expense were as follows: For the Year Ended December 31, 2022 2021 2020 (dollars in thousands) Current tax expense Federal $ 12,906 $ 11,330 $ 7,877 State 5,559 4,862 4,192 18,465 16,192 12,069 Deferred tax expense (benefit) Federal 455 1,840 ( 250 ) State 132 1,059 ( 415 ) 587 2,899 ( 665 ) Total income tax expense $ 19,052 $ 19,091 $ 11,404 The following is a reconciliation of the total income tax expense, calculated at statutory federal income tax rates, to the income tax provision in the consolidated statements of income: For the Year Ended December 31, 2022 2021 2020 (dollars in thousands) Income tax expense at statutory rate of 21.0 % $ 15,112 $ 15,354 $ 9,106 Increase/(decrease) resulting from: State tax, net of federal tax benefit 4,496 4,678 2,984 Tax-exempt income ( 814 ) ( 795 ) ( 694 ) ESOP dividends ( 150 ) ( 145 ) ( 125 ) Bank owned life insurance ( 133 ) ( 165 ) ( 157 ) Compensation limited under 162(m) 193 226 511 Benefit from stock compensation ( 81 ) ( 46 ) — Non-deductible acquisition costs 182 — 186 Non-deductible expenses 44 55 — Impact of CARES Act — — ( 539 ) BOLI surrender, death benefit 310 — — Other ( 107 ) ( 71 ) 132 Total income tax expense $ 19,052 $ 19,091 $ 11,404 The CARES Act was signed into law on March 27, 2020, to help stimulate the United States economy. One of the business tax provisions of the CARES Act included allowing net operating losses (“NOL”) generated by the Company in tax years 2018 and 2019 to be carried back up to five years at the tax rates in effect during those periods, rather than carried forward at current federal tax rates of 21 %. The effect of the Act allowed the Company to recognize lower tax expense associated with NOL carryforwards from 2018 and 2019 (as a result of the Optima Bank and Trust merger) and resulted in a benefit of $ 539,000 during the year ended December 31, 2020. The Company’s 2022 and 2021 net deferred tax assets were measured using a 27.95 % and 27.92 % tax rate, respectively, and consisted of the following components: December 31, 2022 December 31, 2021 (dollars in thousands) Gross deferred tax assets Allowance for credit losses $ 11,142 $ 10,019 Unrealized losses on available for sale securities 7,390 982 Incentive compensation 1,819 1,905 Equity based compensation 1,298 1,347 Lease liabilities 7,661 9,458 ESOP dividends 200 193 Intangibles and fair value marks (merger related) 2,322 658 Other 931 265 Total gross deferred tax assets 32,763 24,827 Gross deferred tax liabilities Deferred loan origination costs ( 2,886 ) ( 2,324 ) Retirement benefits ( 1,745 ) ( 535 ) Depreciation of premises and equipment ( 2,551 ) ( 1,997 ) Right-of-use asset ( 7,014 ) ( 8,733 ) Mortgage servicing rights ( 465 ) ( 303 ) Goodwill ( 115 ) ( 115 ) Derivative transactions 3 ( 835 ) Total gross deferred tax liabilities ( 14,773 ) ( 14,842 ) Net deferred tax asset $ 17,990 $ 9,985 It is management’s belief that it is more likely than not that the reversal of deferred tax liabilities and results of future operations will generate sufficient taxable income to realize the deferred tax assets. Therefore, no valuation allowance was required at either December 31, 2022 and December 31, 2021 for the deferred tax assets. It should be noted, however, that factors beyond management’s control, such as the general state of the economy and real estate values, can affect future levels of taxable income and that no assurance can be given that sufficient taxable income will be generated in future periods to fully absorb deductible temporary differences. At December 31, 2022 and December 31, 2021 , the Company had no unrecognized tax benefits or any uncertain tax positions. The Company does not expect the total amount of unrecognized tax benefits to significantly increase in the next 12 months. The Company’s federal income tax returns are open and subject to examination from the 2019 through 2022 tax return years. The Company’s state income tax returns are open from the 2019 through 2022 tax return years based on individual states’ statute of limitations.

Pension and Retirement Plans

Pension and Retirement Plans	12 Months Ended
	Dec. 31, 2022
Retirement Benefits [Abstract]
Pension and Retirement Plans	14. PENSION AND RETIREMENT PLANS The Company has a noncontributory, defined benefit pension plan (“Pension Plan”) covering substantially all employees hired before May 2, 2011. The Company also provides supplemental retirement benefits to certain current and former executive officers of the Company under the terms of Supplemental Executive Retirement Agreements (“Supplemental Retirement Plan”). The Company also offers postretirement health care benefits for current and future retirees of the Bank. Certain employees receive a fixed monthly benefit at age 65 toward the purchase of postretirement medical coverage. The benefit received is based on the employee’s years of active service. Effective November 7, 2019, the postretirement health care plan was frozen for employees hired after that date. The Company froze the accrual of benefits on the qualified defined benefit pension plan in 2017. The Company did not make any contributions to the qualified defined benefit pension plan during the year ended December 31, 2022. The Company uses a December 31 st measurement date each year to determine the benefit obligations for these plans. Projected benefit obligations and funded status were as follows: Pension Plan Supplemental 2022 2021 2022 2021 (dollars in thousands) Change in projected benefit obligation Obligation at beginning of year $ 47,875 $ 50,117 $ 10,075 $ 10,505 Service cost — — 399 400 Interest cost 1,309 1,211 260 223 Actuarial (gain) loss ( 11,754 ) ( 1,838 ) ( 2,057 ) ( 451 ) Benefits paid ( 1,832 ) ( 1,615 ) ( 617 ) ( 602 ) Obligation at end of year 35,598 47,875 8,060 10,075 Change in plan assets Fair value at beginning of year 60,638 55,802 — — Actual return on plan assets ( 8,457 ) 6,451 — — Employer contribution — — 617 602 Benefits paid ( 1,832 ) ( 1,615 ) ( 617 ) ( 602 ) Fair value at end of year 50,349 60,638 — — Funded status at end of year $ 14,751 $ 12,763 $ ( 8,060 ) $ ( 10,075 ) The funded status of the Company’s Pension Plan is included within other assets and the funded status of the Company’s Supplemental Retirement Plan is included within other liabilities on the Company’s consolidated balance sheets at December 31, 2022 and 2021. Pension Plan Supplemental 2022 2021 2022 2021 (dollars in thousands) Accumulated benefit obligation $ 35,598 $ 47,875 $ 7,627 $ 9,472 Amounts recognized in accumulated other comprehensive income (loss) consisted of: Pension Plan Supplemental 2022 2021 2022 2021 (dollars in thousands) Net actuarial (gain) loss $ 373 $ ( 206 ) $ ( 617 ) $ 1,468 Prior service credit — — — — Total $ 373 $ ( 206 ) $ ( 617 ) $ 1,468 The components of net periodic benefit cost and amounts recognized in other comprehensive income (loss) were as follows: Pension Plan Supplemental 2022 2021 2022 2021 (dollars in thousands) Net periodic benefit cost Service cost $ — $ — $ 399 $ 400 Interest cost 1,309 1,211 260 223 Expected return on assets ( 3,876 ) ( 3,566 ) — — Amortization of prior service credit — ( 3 ) — — Amortization of net actuarial loss — — 28 40 Net periodic expense (benefit) ( 2,567 ) ( 2,358 ) 687 663 Amounts recognized in other comprehensive income (loss) Net actuarial loss/(gain) 579 ( 4,723 ) ( 2,057 ) ( 451 ) Amortization of prior service credit — 3 — — Amortization of net actuarial loss — — ( 28 ) ( 40 ) Total recognized in other comprehensive income (loss) 579 ( 4,720 ) ( 2,085 ) ( 491 ) Total recognized in net periodic expense (benefit) and other $ ( 1,988 ) $ ( 7,078 ) $ ( 1,398 ) $ 172 Weighted-average assumptions used to determine projected benefit obligations are as follows: Pension Plan Supplemental 2022 2021 2022 2021 Discount rate 5.22 % 2.79 % 5.15 % 2.63 % Rate of compensation increase N/A N/A 4.00 % 4.00 % Weighted-average assumptions used to determine the net periodic benefit cost in each year were as follows: Pension Plan Supplemental 2022 2021 2022 2021 Discount rate 2.79 % 2.45 % 2.63 % 2.21 % Expected long-term return on plan assets 6.50 % 6.50 % N/A N/A Rate of compensation increase N/A N/A 4.00 % 4.00 % To develop the expected long-term rate of return on assets assumption for the Pension Plan, the Company considered the historical returns and the future expectations for returns for each asset class, as well as target asset allocations of the pension portfolio. The Company maintains an Investment Policy for its Pension Plan. The objective of this policy is to seek a balance between capital appreciation, current income, and preservation of capital, with a longer-term weighting towards equities because of the extended time horizon of the Pension Plan. The Investment Policy guidelines suggest that the target asset allocation percentages are from 30 % to 60 % in domestic large cap equities, from 5 % to 20 % in domestic small/mid cap equities, from 0 % to 20 % in international and emerging equities, and from 20 % to 60 % in cash and fixed income. The Company’s Pension Plan weighted-average asset allocations by asset category were as follows: December 31, 2022 2021 Equity securities 60 % 68 % Debt securities 33 29 Other — — Cash and equivalents 7 3 Total 100 % 100 % The three broad levels of fair values used to measure the Pension Plan assets are as follows: • Level 1 – Quoted prices for identical assets in active markets. • Level 2 – Quoted prices for similar assets in active markets; quoted prices for identical or similar assets in inactive markets; and model-derived valuations in which all significant inputs and significant value drivers are observable in active markets. • Level 3 – Valuations derived from techniques in which one or more significant inputs or significant value drivers are unobservable in the markets and which reflect the Company’s market assumptions. The following table summarizes the various categories of the Pension Plan’s assets: Fair Value as of December 31, 2022 Level 1 Level 2 Level 3 Total (dollars in thousands) Asset category Cash and cash equivalents $ 3,676 $ — $ — $ 3,676 Fixed income — 12,347 — 12,347 Equity securities Mutual funds Domestic equity 24,201 — — 24,201 International 3,942 — — 3,942 Domestic fixed income 6,183 — — 6,183 Total $ 38,002 $ 12,347 $ — $ 50,349 Fair Value as of December 31, 2021 Level 1 Level 2 Level 3 Total (dollars in thousands) Asset category Cash and cash equivalents $ 1,689 $ — $ — $ 1,689 Fixed income — 13,338 — 13,338 Equity securities Common stock Large cap core 16,940 — — 16,940 Small cap core 2,359 — — 2,359 Mutual funds Domestic equity 10,413 — — 10,413 International 6,579 — — 6,579 Domestic fixed income 9,320 — — 9,320 Total $ 47,300 $ 13,338 $ — $ 60,638 There were no transfers between fair value levels during the years ended December 31, 2022 and December 31, 2021. The Company offers postretirement health care benefits for current and future retirees of the Bank. Employees receive a fixed monthly benefit at age 65 toward the purchase of postretirement medical coverage. The benefit received is based on the employee’s years of active service. The Company uses a December 31 measurement date each year to determine the benefit obligation for this plan. On November 7, 2019, the Company announced its decision to freeze the accrual of benefits to new hires within the plan. The plan is unfunded and plan obligations were $ 424,000 and $ 729,000 at December 31, 2022 and December 31, 2021, respectively. Benefits expected to be paid in the next ten years are as follows: Pension Supplemental Postretirement Total (dollars in thousands) Year-ended December 31, 2023 $ 2,124 $ 611 $ 24 $ 2,759 2024 2,197 606 23 2,826 2025 2,270 602 23 2,895 2026 2,394 597 23 3,014 2027 2,378 592 22 2,992 2028-2032 12,695 3,916 123 16,734 Total $ 24,058 $ 6,924 $ 238 $ 31,220 Employee Profit Sharing and 401(k) Plan The Company maintains a Profit-Sharing Plan (“PSP”) that provides for deferral of federal and state income taxes on employee contributions allowed under Section 401(k) of federal law. The Company matches employee contributions up to 100 % of the first 4 % of each participant’s salary, eligible bonus, and eligible incentive. Employees are eligible to participate in the PSP on the first day of their initial date of service. The Company may also make discretionary contributions to the PSP. Employee Stock Ownership Plan The Company has an Employee Stock Ownership Plan (“ESOP”) for its eligible employees. Employees are eligible to participate upon the attainment of age 21 and the completion of 12 months of service consisting of at least 1,000 hours. Purchases of the Company’s stock by the ESOP will be funded by employer contributions or reinvestment of cash dividends. Total expenses related to the Profit Sharing and ESOP Plans for the years ended December 31, 2022, 2021 , and 2020 amounted to $ 4.5 million, $ 4.0 million, and $ 3.6 million, respectively. Defined Contribution SERP Plan For executives participating in the Defined Contribution SERP Plan (“DC SERP”) plan, the Company made a contribution of 10 % of each executive’s base salary and bonus to his or her account under the Company’s DC SERP. Total expenses related to the Company’s DC SERP for the years ended December 31, 2022, 2021 , and 2020 amounted to $ 271,000 , $ 201,000 , and $ 209,000 , respectively.

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2022
Share-Based Payment Arrangement, Noncash Expense [Abstract]
Share-Based Compensation	15. SHARE-BASED COMPENSATION In 2017, the Company adopted the 2017 Equity and Cash Incentive Plan (the “2017 Plan”) and all future awards from date of adoption are anticipated to be made under the 2017 Plan. The 2017 Plan permits the issuance of restricted stock, restricted stock units (both time and performance-based), stock options, and stock appreciation rights. Restricted stock awards time-vest either over a three-year or five-year period and are fair valued as of the date of grant. The holders of restricted stock awards participate fully in the rewards of stock ownership of the Company, including voting and dividend rights. A summary of restricted stock outstanding as of December 31, 2022 and 2021, and changes during the years ended on those dates, is presented below: December 31, 2022 December 31, 2021 Number Weighted Number Weighted Restricted stock Non-vested at beginning of year 34,622 $ 78.20 31,649 $ 73.07 Granted 14,380 87.10 18,781 82.06 Vested ( 11,450 ) 76.50 ( 11,691 ) 71.27 Forfeited ( 2,980 ) 81.43 ( 4,117 ) 75.97 Non-vested at end of year 34,572 $ 82.19 34,622 $ 78.20 Performance-based restricted stock units vest based upon the Company’s performance over a three-year period and are fair valued as of the date of grant. The holders of performance-based restricted stock units do not participate in the rewards of stock ownership of the Company until vested. A summary of non-vested performance-based restricted stock units outstanding as of December 31, 2022 and 2021, and changes during the years ended on those dates, is presented below: December 31, 2022 December 31, 2021 Number Weighted Number Weighted Performance-based restricted stock units Non-vested at beginning of year 74,699 $ 73.59 75,246 $ 73.41 Granted 37,263 88.18 32,697 77.00 Vested (Performance achieved) ( 34,248 ) 70.36 ( 30,059 ) 76.56 Forfeited ( 5,580 ) 79.92 ( 3,185 ) 75.06 Non-vested at end of year 72,134 $ 80.83 74,699 $ 73.59 Time-based restricted stock units vest over a three-year -period and have been fair valued as of the date of the grant. The holders of time-based restricted stock units do not participate in the rewards of stock ownership of the Company until vested. A summary of non-vested time-based restricted stock units outstanding as of December 31, 2022 and 2021, and changes during the years ended on those dates, is presented below: December 31, 2022 December 31, 2021 Number Weighted Number Weighted Time-based restricted stock units Non-vested at beginning of year 13,836 $ 75.91 14,968 $ 74.84 Granted 8,796 88.18 7,464 77.00 Vested ( 7,417 ) 75.94 ( 7,899 ) 74.95 Forfeited ( 1,664 ) 84.40 ( 697 ) 75.64 Non-vested at end of year 13,551 $ 82.81 13,836 $ 75.91 The following table presents the amounts recognized in the consolidated statements of income for restricted stock, time-based restricted stock units, and performance-based restricted stock units: For the Year Ended December 31, 2022 2021 2020 (dollars in thousands) Share-based compensation expense $ 2,875 $ 3,476 $ 4,923 Related income tax benefit $ 804 $ 970 $ 1,375 The 2017 Plan allows Directors of the Company to receive their annual retainer fee in the form of stock in the Company. Total shares issued under the 2017 Plan in the years ended December 31, 2022 and 2021 were 7,386 and 5,941 , respectively.

Financial Instruments with Off-

Financial Instruments with Off-Balance-Sheet Risk	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Financial Instruments with Off-Balance-Sheet Risk	16. FINANCIAL INSTRUMENTS WITH OFF-BALANCE-SHEET RISK To meet the financing needs of its clients, the Company is a party to financial instruments with off-balance-sheet risk in the normal course of business. These financial instruments are primarily comprised of commitments to extend credit, commitments to sell residential real estate mortgage loans and standby letters of credit. Those instruments involve, to varying degrees, elements of credit and interest rate risk in excess of the amounts recognized in the consolidated balance sheets. The Company’s exposure to credit loss in the event of nonperformance by the other party to the financial instrument for loan commitments and standby letters of credit is represented by the contractual amount of those instruments assuming that the amounts are fully advanced and that collateral or other security is of no value. The Company uses the same credit policies in making commitments and conditional obligations as it does for on-balance-sheet instruments. Off-balance-sheet financial instruments with contractual amounts that present credit risk included the following: December 31, 2022 December 31, 2021 (dollars in thousands) Financial instruments whose contractual amount represents credit risk: Commitments to extend credit: Unused portion of existing lines of credit $ 1,073,567 $ 809,383 Origination of new loans 25,411 70,633 Standby letters of credit 24,234 18,880 Financial instruments whose notional amount exceeds the amount of credit risk: Commitments to sell residential mortgage loans 250 3,920 Standby letters of credit are conditional commitments issued by the Company to guarantee performance of a client to a third party. Those guarantees are primarily issued to support public and private borrowing arrangements. Most guarantees extend for one year. The credit risk involved in issuing letters of credit is essentially the same as that involved in extending loan facilities to clients. The collateral supporting those commitments varies and may include real property, accounts receivable, or inventory. Commitments to extend credit are agreements to lend to a client as long as there is no violation of any condition established in the contract. Commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. Since some of the commitments may expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. The Company evaluates each client’s creditworthiness on a case-by-case basis. The amount of collateral obtained upon extension of the credit is based on management’s credit evaluation of the client. Collateral held varies, but may include primary residences, accounts receivable, inventory, property, plant and equipment, and income-producing CRE. See Note 21 - Derivatives and Hedging Activities for a discussion of the Company’s derivatives and hedging activities.

Commitment and Contingencies

Commitment and Contingencies	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	17. COMMITMENTS AND CONTINGENCIES Lease Commitments . The Company is obligated under various lease agreements covering its main office, branch offices, and other locations. These agreements are accounted for as operating leases and their terms expire betw een 2022 and 2032 and, in some instances, contain options to renew for periods up to 25 years. The Company recognizes its operating leases on its consolidated balance sheet by recording a lease liability, representing the Company’s legal obligation to make lease payments, and a ROU asset, representing the Company’s legal right to use the leased office space and banking centers. The Company, by policy, does not include renewal options for leases as part of its ROU assets and lease liabilities unless they are deemed reasonably certain to exercise. The Company does not have any material sub-lease agreements. Operating lease expenses are comprised of operating lease costs and variable lease costs, net of sublease income, and are recognized over the lease term. Variable lease payments that are not dependent on an index or a rate or changes in variable payments based on an index or rate after the commencement date are excluded from the measurement of the lease liability, recognized in the period incurred and included within variable lease costs below. The Company determines whether a contract contains a lease based on whether a contract, or a part of a contract, conveys the right to control the use of an identified asset for a period of time in exchange for consideration. The discount rate is determined as either the rate implicit in the lease or, when a rate cannot be readily determined, the Company’s incremental borrowing rate. The incremental borrowing rate is the rate of interest that the Company would have to pay to borrow on a collateralized basis over a similar term. The components of operating lease cost and other related information are as follows: For the Year Ended December 31, 2022 2021 2020 (dollars in thousands) Operating lease cost $ 6,965 $ 6,976 $ 6,691 Variable lease cost (cost excluded from lease payments) 38 13 2 Sublease income ( 316 ) ( 65 ) ( 65 ) Total operating lease cost $ 6,687 $ 6,924 $ 6,628 Other Information Cash paid for amounts included in the measurement of lease liabilities - operating cash flows for operating leases $ 7,263 $ 7,259 $ 6,547 Operating Lease - operating cash flows (liability reduction) 6,401 6,252 5,430 Weighted average lease term - operating leases 5.45 Years 6.13 Years 6.90 Years Weighted average discount rate - operating leases 3.01 % 2.94 % 2.98 % The total minimum lease payments due in future periods under these agreements in effect at December 31, 2022 and December 31, 2021 were as follows: Future Minimum December 31, 2022 Lease Payments (dollars in thousands) 2023 $ 7,085 2024 6,085 2025 5,118 2026 3,882 2027 2,079 Thereafter 5,883 Total minimum lease payments $ 30,132 Less: interest ( 2,719 ) Total lease liability $ 27,413 Several lease agreements contain clauses calling for escalation of minimum lease payments contingent on increases in real estate taxes, gross income adjustments, percentage increases in the consumer price index, and certain ancillary maintenance costs. Total rental expense was $ 7.6 million, $ 7.3 million, and $ 7.0 million for the years ended December 31, 2022, 2021, and 2020, respectively. Change in Control Agreements . The Company has entered into agreements with its Chief Executive Officer and with certain other senior officers, whereby, following the occurrence of a change in control of the Company, if employment is terminated (except because of death, retirement, disability, or for “cause” as defined in the agreements) or is voluntarily terminated for “good reason,” as defined in the agreements, said officers will be entitled to receive additional compensation, as defined in the agreements.

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Shareholders' Equity	18. SHAREHOLDERS’ EQUITY Capital guidelines issued by the Federal Reserve Bank and by the FDIC require that the Company and the Bank maintain minimum capital levels for capital adequacy purposes. These regulations also require banks and their holding companies to maintain higher capital levels to be considered “well-capitalized.” Failure to meet minimum capital requirements can initiate certain mandatory, and possibly additional discretionary actions by regulators that, if undertaken, could have a direct material effect on the Company’s financial statements. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, there are specific capital guidelines that involve quantitative measures of assets, liabilities, and certain off-balance-sheet items as calculated under regulatory accounting practices. The Capital Rules: (i) include “Common Equity Tier 1” (“CET1”) and related regulatory capital ratio of CET1 to risk-weighted assets; (ii) specify that Tier 1 capital consists of CET1 and “Additional Tier 1 capital” instruments meeting certain revised requirements; (iii) mandate that most deductions/adjustments to regulatory capital measures be made to CET1 and not to the other components of capital; and (iv) expand the scope of the deductions from and adjustments to capital as compared to existing regulations. Under the Capital Rules, for most banking organizations, including the Company, the most common form of Additional Tier 1 capital is non-cumulative perpetual preferred stock, and the most common forms of Tier 2 capital are subordinated notes and a portion of the allowance for credit losses, in each case, subject to the Capital Rules’ specific requirements. Pursuant to the Capital Rules, effective January 1, 2015, the minimum capital ratios are as follows: • 4.5 % CET1 to risk-weighted assets; • 6.0 % Tier 1 capital (that is, CET1 plus Additional Tier 1 capital) to risk-weighted assets; • 8.0 % Total capital (that is, Tier 1 capital plus Tier 2 capital) to risk-weighted assets; and • 4.0 % Tier 1 capital to average consolidated assets as reported on consolidated financial statements (called “leverage ratio”). Additionally, the Company is required to maintain additional capital conservation buffer of 2.5 % of CET1, effectively resulting in minimum ratios inclusive of the capital conservation buffer of (i) CET1 to risk-weighted assets of at least 7 %, (ii) Tier 1 capital to risk-weighted assets of at least 8.5 %, and (iii) total capital to risk-weighted assets of at least 10.5 %. Management believes that as of December 31, 2022 and 2021, the Company and the Bank met all applicable minimum capital requirements and were considered “well-capitalized” by both the Federal Reserve Board and the FDIC. The Company adopted ASU 2016-13 on January 1, 2020. The joint federal bank regulatory agencies issued an interim final rule that allows banking organizations to phase-in the effects of the CECL accounting standard in their regulatory capital, over a three-year period from January 1, 2022 through December 31, 2024. The Company did not elect to delay the adoption of CECL and did not adopt the transition period for regulatory capital. The Company’s and the Bank’s actual and required capital measures were as follows: Actual Minimum Capital Minimum To Be Amount Ratio Amount Ratio Amount Ratio (dollars in thousands) At December 31, 2022 Cambridge Bancorp: Total capital (to risk-weighted assets) $ 506,239 13.5 % $ 393,285 10.5 % N/A N/A Tier 1 capital (to risk-weighted assets) 466,369 12.5 % 318,373 8.5 % N/A N/A Common equity tier I capital (to risk-weighted assets) 466,369 12.5 % 262,190 7.0 % N/A N/A Tier 1 capital (to average assets) 466,369 8.5 % 219,309 4.0 % N/A N/A Cambridge Trust Company: Total capital (to risk-weighted assets) $ 490,175 13.1 % $ 393,246 10.5 % $ 374,520 10.0 % Tier 1 capital (to risk-weighted assets) 450,305 12.0 % 318,342 8.5 % 299,616 8.0 % Common equity tier I capital (to risk-weighted assets) 450,305 12.0 % 262,164 7.0 % 243,438 6.5 % Tier 1 capital (to average assets) 450,305 8.2 % 219,296 4.0 % 274,120 5.0 % Actual Minimum Capital Minimum To Be Amount Ratio Amount Ratio Amount Ratio (dollars in thousands) At December 31, 2021 Cambridge Bancorp: Total capital (to risk-weighted assets) $ 420,398 13.6 % $ 325,617 10.5 % N/A N/A Tier 1 capital (to risk-weighted assets) 384,518 12.4 % 263,595 8.5 % N/A N/A Common equity tier I capital (to risk-weighted assets) 384,518 12.4 % 217,078 7.0 % N/A N/A Tier 1 capital (to average assets) 384,518 8.3 % 185,015 4.0 % N/A N/A Cambridge Trust Company: Total capital (to risk-weighted assets) $ 409,806 13.2 % $ 325,587 10.5 % $ 310,082 10.0 % Tier 1 capital (to risk-weighted assets) 373,926 12.1 % 263,570 8.5 % 248,066 8.0 % Common equity tier I capital (to risk-weighted assets) 373,926 12.1 % 217,058 7.0 % 201,554 6.5 % Tier 1 capital (to average assets) 373,926 8.1 % 185,003 4.0 % 231,254 5.0 %

Comprehensive Income (Loss)

Comprehensive Income (Loss)	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Comprehensive Income (Loss)	19. COMPREHENSIVE INCOME (LOSS) Comprehensive income (loss) is defined as all changes to shareholders’ equity except investments by and distributions to shareholders. Net income is a component of comprehensive income (loss), with all other components referred to in the aggregate as “other comprehensive income (loss).” The Company’s other comprehensive income (loss) consists of unrealized gains or losses on securities held at year-end classified as available for sale and, cash flow hedges, and the component of the unfunded retirement liability computed in accordance with the requirements of ASC Topic 715, “ Compensation – Retirement Benefits. ” The before-tax and after-tax amount of each of these categories, as well as the tax (expense)/benefit of each, is summarized as follows: For the Year Ended For the Year Ended For the Year Ended Before Tax Net-of- Before Tax Net-of- Before Tax Net-of- (dollars in thousands) Available for sale securities Unrealized holding gains (losses) $ ( 25,144 ) $ 6,408 $ ( 18,736 ) $ ( 6,245 ) $ 1,623 $ ( 4,622 ) $ 3,630 $ ( 830 ) $ 2,800 Reclassification adjustment for (gains) losses realized in net income (1) — — — — — — ( 73 ) 16 ( 57 ) Interest rate swaps designated as cash flow hedges Unrealized holding gains (losses) ( 2,170 ) 607 ( 1,563 ) ( 1,329 ) 370 ( 959 ) 6,602 ( 1,844 ) 4,758 Reclassification adjustment for (gains) losses recognized in net income (2) ( 832 ) 232 ( 600 ) ( 2,587 ) 723 ( 1,864 ) ( 1,879 ) 525 ( 1,354 ) Defined benefit retirement plans Net change in retirement liability 1,818 ( 508 ) 1,310 5,273 ( 1,472 ) 3,801 ( 1,695 ) 463 ( 1,232 ) Total other comprehensive income (loss) $ ( 26,328 ) $ 6,739 $ ( 19,589 ) $ ( 4,888 ) $ 1,244 $ ( 3,644 ) $ 6,585 $ ( 1,670 ) $ 4,915 (1) Reported in gain (loss) on disposition of investment securities line item in the Consolidated Statements of Income. (2) Reported in interest on payable loans line item in the Consolidated Statements of Income. The components of accumulated other comprehensive income are as follows: December 31, 2022 December 31, 2021 Before Tax Amount Deferred (tax) benefit Net-of-tax Amount Before Tax Amount Deferred (tax) benefit Net-of-tax Amount (dollars in thousands) Available for sale securities $ ( 28,611 ) $ 7,390 $ ( 21,221 ) $ ( 3,467 ) $ 982 $ ( 2,485 ) Interest Rate swaps designated as cash flow hedges ( 14 ) 4 ( 10 ) 2,988 ( 836 ) 2,152 Defined benefit retirement plans 600 ( 168 ) 432 ( 1,218 ) 341 ( 877 ) Total accumulated other comprehensive income $ ( 28,025 ) $ 7,226 $ ( 20,799 ) $ ( 1,697 ) $ 487 $ ( 1,210 )

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2022
Earnings Per Share [Abstract]
Earnings Per Share	20. EARNINGS PER SHARE The following represents a reconciliation between basic and diluted earnings per share: For the Year Ended December 31, 2022 2021 2020 (dollars in thousands, except per share data) Earnings per common share - basic: Numerator: Net income $ 52,909 $ 54,024 $ 31,959 Less dividends and undistributed earnings allocated ( 257 ) ( 250 ) ( 47 ) Net income applicable to common shareholders $ 52,652 $ 53,774 $ 31,912 Denominator: Weighted average common shares outstanding 7,163 6,926 6,289 Earnings per common share - basic $ 7.35 $ 7.76 $ 5.07 Earnings per common share - diluted: Numerator: Net income $ 52,909 $ 54,024 $ 31,959 Less dividends and undistributed earnings allocated ( 257 ) ( 250 ) ( 47 ) Net income applicable to common shareholders $ 52,652 $ 53,774 $ 31,912 Denominator: Weighted average common shares outstanding 7,163 6,926 6,289 Dilutive effect of common stock equivalents 51 65 55 Weighted average diluted common shares outstanding 7,214 6,991 6,344 Earnings per common share - diluted $ 7.30 $ 7.69 $ 5.03

Derivatives And Hedging Activit

Derivatives And Hedging Activities	12 Months Ended
	Dec. 31, 2022
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives And Hedging Activities	21. DERIVATIVES and Hedging Activities The Company utilizes interest rate swaps and floors to mitigate exposure to interest rate risk and to facilitate the needs of its clients. The Company’s derivative financial instruments are used to manage differences in the amount, timing, and duration of the Company’s known or expected cash receipts principally related to the Company’s assets. The Company is exposed to certain risk arising from both its business operations and economic conditions. The Company principally manages its exposures to a wide variety of business and operational risks through management of its core business activities. The Company manages economic risks, including interest rate, liquidity, and credit risk primarily by managing the amount, sources, and duration of its assets and liabilities and the use of derivative financial instruments. Specifically, the Company enters into derivative financial instruments to manage exposures that arise from business activities that result in the receipt or payment of future known and uncertain cash amounts, the value of which are determined by interest rates. The Company’s existing credit derivatives result from participations loan participation arrangements, therefore, are not used to manage interest rate risk in the Company’s assets or liabilities Cash Flow Hedges of Interest Rate Risk The Company uses interest floors to manage its exposure to interest rate movements. Interest rate floors designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty if interest rates fall below the strike rate on the contract in exchange for an up-front premium. The Company’s objectives in using interest rate derivatives are to add stability to interest income and to manage its exposure to interest rate movements. To accomplish this objective, the Company primarily uses interest rate floors as part of its interest rate risk management strategy. Interest rate floors designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty if interest rates fall below the strike rate on the contract in exchange for an up-front premium. During 2022, such derivatives were used to hedge the variable cash flows associated with variable-rate assets. For derivatives designated and that qualify as cash flow hedges of interest rate risk, the gain or loss on the derivative is recorded in AOCI and subsequently reclassified into interest income in the same period(s) during which the hedged transaction affects earnings. Gains and losses on the derivative representing hedge components excluded from the assessment of effectiveness are recognized over the life of the hedge on a systematic and rational basis. The earnings recognition of excluded components is presented in interest income. Amounts reported in AOCI related to derivatives will be reclassified to interest income as interest payments are received on the Company’s variable-rate assets. During fiscal year 2023, the Company estimates that $ 539,000 will be reclassified out of AOCI into earnings, as a decrease to interest income. Non-designated Hedges Derivatives not designated as hedges are not speculative and result from a service the Company provides to certain clients. For the Company’s clients, these are interest rate swaps and risk participation agreements. Interest Rate Swaps. The Company enters into interest rate swap contracts to help commercial loan borrowers manage their interest rate risk. The interest rate swap contracts with commercial loan borrowers allow them to convert floating-rate loan payments to fixed rate loan payments. When the Company enters into an interest rate swap contract with a commercial loan borrower, it simultaneously enters into a “mirror” swap contract with a third party. The third party exchanges the client’s fixed-rate loan payments for floating-rate loan payments. These derivatives are not designated as hedges and therefore, changes in fair value are recognized in earnings. Because these derivatives have mirror-image contractual terms, the changes in fair value substantially offset each other through earnings. Fees earned in connection with the execution of derivatives related to this program are recognized in earnings through loan related derivative income. The credit risk associated with swap transactions is the risk of default by the counterparty. To minimize this risk, the Company enters into interest rate agreements only with highly rated counterparties that management believes to be creditworthy. The notional amounts of these agreements do not represent amounts exchanged by the parties and, thus, are not a measure of the potential loss exposure. Risk Participation Agreements. The Company enters into risk participation agreements (“RPAs”) with other banks participating in commercial loan arrangements. Participating banks guarantee the performance on borrower-related interest rate swap contracts. RPAs are derivative financial instruments and are recorded at fair value. These derivatives are not designated as hedges and therefore, changes in fair value are recognized in earnings. Under a risk participation-out agreement, a derivative asset, the Company participates out a portion of the credit risk associated with the interest rate swap position executed with the commercial borrower, for a fee paid to the participating bank. Under a risk participation-in agreement, a derivative liability, the Company assumes, or participates in, a portion of the credit risk associated with the interest rate swap position with the commercial borrower for a fee received from the other bank. The following tables present the notional amount, the location, and fair values of derivative instruments in the Company’s consolidated balance sheets: December 31, 2022 Derivative Assets Derivative Liabilities Notional Amount Balance Sheet Fair Value Notional Amount Balance Sheet Fair Value (dollars in thousands) (dollars in thousands) Derivatives designated as hedging instruments Interest rate contracts $ 250,000 Other Assets $ 1,966 $ — Other Liabilities $ — Total derivatives designated as hedging instruments $ 1,966 $ — Derivatives not designated as hedging instruments Loan related derivative contracts Interest rate contracts $ 499,619 Other Assets $ 50,784 $ 499,619 Other Liabilities $ 50,784 Risk participation agreements-out to counterparties 46,604 Other Assets 23 — Other Liabilities — Risk participation agreements-in with counterparties — Other Assets — 71,046 Other Liabilities 43 Total derivatives not designated as hedging instruments $ 50,807 $ 50,827 December 31, 2021 Derivative Assets Derivative Liabilities Notional Amount Balance Sheet Fair Value Notional Amount Balance Sheet Fair Value (dollars in thousands) (dollars in thousands) Derivatives designated as hedging instruments Interest rate contracts $ 150,000 Other Assets $ 3,513 $ — Other Liabilities $ — Total derivatives designated as hedging instruments $ 3,513 $ — Derivatives not designated as hedging instruments Loan related derivative contracts Interest rate contracts $ 522,581 Other Assets $ 23,431 $ 522,581 Other Liabilities $ 23,431 Risk participation agreements-out to counterparties 47,988 Other Assets 107 — Other Liabilities — Risk participation agreements-in with counterparties — Other Assets — 109,510 Other Liabilities 293 Total derivatives not designated as hedging instruments $ 23,538 $ 23,724 The following tables present the effect of cash flow hedge accounting on AOCI as of the periods presented: Twelve Months Ended December 31, 2022 Amount of Gain or (Loss) Recognized in OCI Amount of Gain or (Loss) Recognized in OCI Included Component Amount of Gain or (Loss) Recognized in OCI Excluded Component Location of Gain or (Loss) Amount of Gain or (Loss) Reclassified from AOCL into Income Amount of Gain or (Loss) Reclassified from AOCL into Income Included Component Amount of Gain or (Loss) Reclassified from AOCL into Income Excluded Component (dollars in thousands) (dollars in thousands) Interest rate contracts $ ( 2,170 ) $ 607 $ ( 1,563 ) Interest Income $ 832 $ 1,026 $ ( 194 ) Twelve Months Ended December 31, 2021 Amount of Gain or (Loss) Recognized in OCI Amount of Gain or (Loss) Recognized in OCI - Included Component Amount of Gain or (Loss) Recognized in OCI - Excluded Component Location of Gain or (Loss) Amount of Gain or (Loss) Reclassified from AOCI into Income Amount of Gain or (Loss) Reclassified from AOCI into Income Included Component Amount of Gain or (Loss) Reclassified from AOCI into Income Excluded Component (dollars in thousands) (dollars in thousands) Interest rate contracts $ ( 1,329 ) $ 370 $ ( 959 ) Interest Income $ 2,587 $ 2,782 $ ( 195 ) The following table presents the effect of the Company’s derivative financial instruments that are not designated as hedging instruments on the consolidated statements of income as of the periods presented: Amount of Gain or (Loss) Recognized in Income For the Year Ended December 31, 2022 2021 2020 Location of Gain or (Loss) (dollars in thousands) Other contracts Loan-related derivative income $ ( 166 ) $ ( 124 ) $ 155 Credit-risk-related Contingent Features By entering into derivative transactions, the Company is exposed to credit risk to the extent that counterparties to the derivative contracts do not perform as required. Should a counterparty fail to perform under the terms of a derivative contract, the Company’s credit exposure on interest rate swaps is limited to the net positive fair value and accrued interest of all swaps with each counterparty. The Company seeks to minimize counterparty credit risk through credit approvals, limits, monitoring procedures, and obtaining collateral, where appropriate. Institutional counterparties must have an investment grade credit rating and be approved by the Company’s Board of Directors. As such, management believes the risk of incurring credit losses on derivative contracts with institutional counterparties is remote. The Company has agreements with its derivative counterparties that contain a provision where if the Company defaults on any of its indebtedness, including default where repayment of the indebtedness has not been accelerated by the lender, then the Company could also be declared in default on its derivative obligations. In addition, the Company also has agreements with certain of its derivative counterparties that contain a provision where if the Company fails to maintain its status as a well- capitalized institution, then the counterparty could terminate the derivative position(s) and the Company would be required to settle its obligations under the agreements. Balance Sheet Offsetting Certain financial instruments may be eligible for offset in the consolidated balance sheet and/or subject to master netting arrangements or similar agreements. The Company’s derivative transactions with institutional counterparties are generally executed under International Swaps and Derivative Association (“ISDA”) master agreements which include “right of set-off” provisions. In such cases there is generally a legally enforceable right to offset recognized amounts and there may be an intention to settle such amounts on a net basis. Generally, the Company does not offset such financial instruments for financial reporting purposes. The following tables present the information about financial instruments that are eligible for offset in the consolidated balance sheets as of December 31, 2022 and 2021: Gross Amounts Not Offset Gross Amounts Recognized Gross Amounts Offset Net Amounts Recognized Financial Instruments Collateral Pledged (Received) Net Amount December 31, 2022 (dollars in thousands) Offsetting of Derivative Assets Derivative Assets $ 52,773 $ — $ 52,773 $ 48 $ ( 52,130 ) $ 595 Offsetting of Derivative Liabilities Derivative Liabilities $ 50,827 $ — $ 50,827 $ 48 $ — $ 50,875 Gross Amounts Not Offset Gross Amounts Recognized Gross Amounts Offset Net Amounts Recognized Financial Instruments Collateral Pledged (Received) Net Amount December 31, 2021 (dollars in thousands) Offsetting of Derivative Assets Derivative Assets $ 27,051 $ — $ 27,051 $ 6,365 $ — $ 20,686 Offsetting of Derivative Liabilities Derivative Liabilities $ 23,724 $ — $ 23,724 $ 6,365 $ 14,011 $ 3,348 At December 31, 2022, there were no derivatives in a net liability position related to these financial instruments. At December 31, 2021, the fair value of derivatives in a net liability position, which includes accrued interest but excludes any adjustment for nonperformance risk, related to these agreements was $ 14.0 million. At December 31, 2021 , the Company has minimum collateral posting thresholds with certain of its derivative counterparties and has posted cash collateral of $ 13.3 million against these agreements. If the Company had breached any of these provisions at December 31, 2021 , it could have been required to settle its obligations under the agreements at their termination value of $ 14.0 million .

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Fair Value Measurements	22. FAIR VALUE MEASUREMENTS The following is a summary of the carrying values and estimated fair values of the Company’s significant financial instruments as of the dates indicated: December 31, 2022 December 31, 2021 Carrying Estimated Carrying Estimated (dollars in thousands) Financial assets Cash and cash equivalents $ 30,719 $ 30,719 $ 180,153 $ 180,153 Securities available for sale 153,416 153,416 197,803 197,803 Securities held to maturity 1,051,997 885,586 977,061 971,092 Loans, net 4,025,082 3,783,051 3,284,610 3,230,339 Loans held for sale — — 1,490 1,528 FHLB of Boston stock 6,264 6,264 4,816 4,816 Accrued interest receivable 14,118 14,118 9,162 9,162 Mortgage servicing rights 1,665 2,336 1,083 1,518 Interest rate contracts 1,966 1,966 3,513 3,513 Loan level interest rate swaps 50,784 50,784 23,431 23,431 Risk participation agreements out to counterparties 23 23 107 107 Financial liabilities Deposits 4,815,376 4,810,695 4,331,152 4,330,991 Borrowings 105,212 105,202 16,510 16,523 Loan level interest rate swaps 50,784 50,784 23,431 23,431 Risk participation agreements in with counterparties 43 43 293 293 The Company follows ASC Topic 820, Fair Value Measurements and Disclosures, for financial assets and liabilities. ASC Topic 820 defines fair value, establishes a framework for measuring fair value, and expands disclosure requirements about fair value measurements. ASC Topic 820, among other things, emphasizes that fair value is a market-based measurement, not an entity-specific measurement, and states that a fair value measurement should be determined based on the assumptions the market participants would use in pricing the asset or liability. In addition, ASC Topic 820 specifies a hierarchy of valuation techniques based on whether the types of valuation information (“inputs”) are observable or unobservable. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect the Company’s market assumptions. These two types of inputs have created the following fair value hierarchy: • Level 1 – Quoted prices for identical assets or liabilities in active markets. • Level 2 – Quoted prices for similar assets or liabilities in active markets; quoted prices for identical or similar assets or liabilities in inactive markets; and model-derived valuations in which all significant inputs and significant value drivers are observable in active markets. • Level 3 – Valuations derived from techniques in which one or more significant inputs or significant value drivers are unobservable in the markets and which reflect the Company’s market assumptions. Under ASC Topic 820, fair values are based on the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When available, the Company uses quoted market prices to determine fair value. If quoted prices are not available, fair value is based upon valuation techniques, such as matrix pricing or other models that use, where possible, current market-based or independently sourced market parameters, such as interest rates. If observable market-based inputs are not available, the Company uses unobservable inputs to determine appropriate valuation adjustments using methodologies applied consistently over time. Valuation techniques based on unobservable inputs are highly subjective and require judgments regarding significant matters, such as the amount and timing of future cash flows and the selection of discount rates that may appropriately reflect market and credit risks. Changes in these judgments often have a material impact on the fair value estimates. In addition, since these estimates are as of a specific point in time, they are susceptible to material near-term changes. The fair values disclosed do not reflect any premium or discount that could result from offering significant holdings of financial instruments at bulk sale, nor do they reflect the possible tax ramifications or estimated transaction costs. Changes in economic conditions may also dramatically affect the estimated fair values. The Company uses fair value measurements to record fair value adjustments to certain assets and liabilities and to determine fair value disclosures. Securities available for sale, derivative instruments, and hedges are recorded at fair value on a recurring basis. Additionally, from time to time, the Company may be required to record at fair value other assets on a nonrecurring basis, such as loans held for sale, mortgage servicing rights, other real estate owned, and collateral dependent impaired loans. The Company uses an exit price notion for its fair value disclosures. The following tables summarize certain assets reported at fair value on a recurring basis: Fair Value as of December 31, 2022 Level 1 Level 2 Level 3 Total (dollars in thousands) Measured on a recurring basis Securities available for sale U.S. GSE obligations $ — $ 19,733 $ — $ 19,733 Mortgage-backed securities — 132,683 — 132,683 Corporate debt securities — 1,000 — 1,000 Other assets Interest rate swaps with clients — 50,784 — 50,784 Risk participation agreements-out to counterparties — 23 — 23 Interest rate contracts — 1,966 — 1,966 Other liabilities Interest rate swaps with counterparties — 50,784 — 18,161 Risk participation agreements-in with counterparties — 43 — 43 Fair Value as of December 31, 2021 Level 1 Level 2 Level 3 Total (dollars in thousands) Measured on a recurring basis Securities available for sale U.S. GSE obligations $ — $ 23,011 $ — $ 23,011 Mortgage-backed securities — 173,028 — 173,028 Corporate debt securities — 1,764 — 1,764 Other assets Interest rate swaps with clients — 23,431 — 23,431 Risk participation agreements-out to counterparties — 107 — 107 Interest rate contracts — 3,513 — 3,513 Other liabilities Interest rate swaps with counterparties — 23,431 — 23,431 Risk participation agreements-in with counterparties — 293 — 293 The following table presents the carrying value of assets held at December 31, 2022 and 2021, which were measured at fair value on a non-recurring basis: December 31, 2022 Level 1 Level 2 Level 3 Total (dollars in thousands) Items recorded at fair value on a non-recurring basis Assets Individually evaluated collateral dependent loans $ — $ — $ 103 $ 103 Total $ — $ — $ 103 $ 103 December 31, 2021 Level 1 Level 2 Level 3 Total (dollars in thousands) Items recorded at fair value on a non-recurring basis Assets Loans held for sale $ 1,490 $ — $ — $ 1,490 Individually evaluated collateral dependent loans — — 130 130 Total $ 1,490 $ — $ 130 $ 1,620 Individually evaluated collateral dependent loans . Collateral dependent loans are carried at the lower of cost or fair value of the collateral less estimated costs to sell which approximates fair value. The Company uses the appraisal value of the collateral and applies certain adjustments depending on the nature, quality, and type of collateral securing the loan. Loans held for sale . Loans held for sale are carried at the lower of fair value or carrying value (unpaid principal and unamortized loans fees). Other Real Estate Owned . These properties are carried at fair value less estimated costs to sell. Mortgage servicing rights . These assets are carried at the fair value determined by estimating the present value of future net cash flows, taking into consideration market loan prepayment speeds, discount rates, servicing costs, and other economic factors. There were no transfers between fair value levels for the years ended December 31, 2022 and 2021. The following is a description of the principal valuation methodologies used by the Company to estimate the fair values of its financial instruments. Investment Securities For investment securities, fair values are primarily based upon valuations obtained from a national pricing service which uses matrix pricing with inputs that are observable in the market or can be derived from, or corroborated by, observable market data. When available, quoted prices in active markets for identical securities are utilized. Loans Held for Sale For loans held for sale, fair values are estimated using projected future cash flows, discounted at rates based upon either trades of similar loans or mortgage-backed securities, or at current rates at which similar loans would be made to borrowers with similar credit ratings and for similar remaining maturities. Loans For most categories of loans, fair values are estimated using projected future cash flows, discounted at rates based upon current rates at which similar loans would be made to borrowers with similar credit ratings, and for similar remaining maturities. Projected estimated cash flows are adjusted for prepayment assumptions, liquidity premium assumptions, and credit loss assumptions. Loans that are deemed to be impaired in accordance with ASC Topic 310, Receivables , are valued based upon the lower of cost or fair value of the underlying collateral. FHLB of Boston Stock The fair value of FHLB of Boston stock equals its carrying value since such stock is only redeemable at its par value. Deposits The fair value of non-maturity deposit accounts is the amount payable on demand at the reporting date. This amount does not take into account the value of the Company’s long-term relationships with core depositors. The fair value of fixed-maturity certificates of deposit is estimated using a replacement cost of funds approach and is based upon rates currently offered for deposits of similar remaining maturities. Borrowings For long-term borrowings, fair values are estimated using future cash flows, discounted at rates based upon current costs for debt securities with similar terms and remaining maturities. Other Financial Assets Cash and cash equivalents and accrued interest receivable have fair values which approximate their respective carrying values because these instruments are payable on demand or have short-term maturities and present relatively low credit risk and interest rate risk. Derivative Instruments and Hedges The valuation of these instruments is determined using widely accepted valuation techniques including discounted cash flow analysis on the expected cash flows of each derivative. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate curves and implied volatilities. The Company incorporates credit valuation adjustments to appropriately reflect nonperformance risk in the fair value measurements. In adjusting the fair value of its derivative contracts for the effect of nonperformance risk, the Company has considered the impact of netting and any applicable credit enhancements, such as collateral postings. Off-Balance-Sheet Financial Instruments In the course of originating loans and extending credit, the Company will charge fees in exchange for its commitment. While these commitment fees have value, the Company has not estimated their value due to the short-term nature of the underlying commitments and their immateriality. Values Not Determined In accordance with ASC Topic 820, the Company has not estimated fair values for non-financial assets such as banking premises and equipment, goodwill, the intangible value of the Company’s portfolio of loans serviced for itself, and the intangible value inherent in the Company’s deposit relationships (i.e., core deposits), among others. Accordingly, the aggregate fair value amounts presented do not represent the underlying value of the Company.

Condensed Financial Statements

Condensed Financial Statements of Parent Company	12 Months Ended
	Dec. 31, 2022
Condensed Financial Information Disclosure [Abstract]
Condensed Financial Statements of Parent Company	23. Condensed Financial Statements of Parent Company The condensed balance sheets of Cambridge Bancorp, the Parent Company, as of December 31, 2022 and December 31, 2021 and the condensed statements of income and cash flows for each of the years in the three-year period ended December 31, 2022 are presented below. The statements of changes in shareholders’ equity are identical to the consolidated statements of changes in shareholders’ equity and are therefore not presented here. Condensed Balance Sheet December 31, 2022 2021 (dollars in thousands) ASSETS Cash and cash equivalents $ 15,747 $ 10,303 Goodwill 33 33 Other assets 318 289 Investment in subsidiary 501,454 427,212 Total assets $ 517,552 $ 437,837 SHAREHOLDERS’ EQUITY Shareholders’ equity $ 517,552 $ 437,837 Total shareholders’ equity $ 517,552 $ 437,837 Condensed Statements of Income For the Year Ended December 31, 2022 2021 2020 (dollars in thousands) Income Dividends from subsidiary $ 24,734 $ 25,995 $ 21,639 Total income 24,734 25,995 21,639 Expenses Interest expense — — 444 Other expenses 148 150 110 Total expenses 148 150 554 Income before income taxes and equity in undistributed income of subsidiary 24,586 25,845 21,085 Income tax benefit ( 40 ) ( 42 ) ( 153 ) Income of parent company 24,626 25,887 21,238 Equity in undistributed income of subsidiary 28,283 28,137 10,721 Net income $ 52,909 $ 54,024 $ 31,959 Condensed Statements of Cash Flows For the Year Ended December 31, 2022 2021 2020 (dollars in thousands) CASH FLOWS FROM OPERATING ACTIVITIES: Net income $ 52,909 $ 54,024 $ 31,959 Adjustments to reconcile net income to net cash provided Deferred income tax benefit ( 40 ) ( 42 ) ( 153 ) Change in other assets, net 12 — 3,032 Change in other liabilities, net — 13 444 Undistributed income of subsidiary ( 28,283 ) ( 28,137 ) ( 10,721 ) Net cash provided by operating activities 24,598 25,858 24,561 CASH FLOWS FROM INVESTING ACTIVITIES: Cash paid in business combinations — — ( 534 ) Net cash used in investing activities — — ( 534 ) CASH FLOWS FROM FINANCING ACTIVITIES: Proceeds from the issuance of common stock 580 519 452 Repurchase of common stock ( 1,320 ) ( 1,440 ) ( 556 ) Redemption of subordinate debt — — ( 10,600 ) Cash dividends paid on common stock ( 18,414 ) ( 16,554 ) ( 13,083 ) Net cash provided by/(used in) financing activities ( 19,154 ) ( 17,475 ) ( 23,787 ) Net increase (decrease) in cash 5,444 8,383 240 Cash at beginning of year 10,303 1,920 1,680 Cash at end of year $ 15,747 $ 10,303 $ 1,920 SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION: Significant non-cash transactions Common Stock issued to shareholders due to merger $ 62,850 $ — $ 87,163

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”).
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements. Actual results could differ from those estimates. The allowance for credit losses, the valuation of deferred tax assets, and the valuation of assets acquired and liabilities assumed in business combinations are particularly subject to change.
Reclassifications	Reclassifications Certain amounts in the prior year’s financial statements may have been reclassified to conform with the current year’s presentation.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents consist of cash on hand, amounts due from banks, and overnight investments.
Investment Securities	Investment Securities Investment securities are classified as either “held to maturity” or “available for sale” in accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 320, Investments – Debt Securities. Debt securities that management has the positive intent and ability to hold to maturity are classified as held to maturity and recorded at amortized cost. Debt securities not classified as held to maturity are classified as available for sale and carried at fair value with unrealized after-tax gains and losses reported net as a separate component of shareholders’ equity. The Company classifies its securities based on its intention at the time of purchase. Purchase premiums and discounts are recognized in interest income using the effective yield or straight-line method over the term of the securities, except for callable debt securities for which the purchase premiums are recognized through the earliest call date. Gains and losses on the sale of debt securities are recorded on the trade date and determined using the specific identification method. Allowance for Credit Losses - Held to Maturity Securities The Company measures expected credit losses on held to maturity debt securities on a collective basis by security type and risk rating where available. The reserve for each pool is calculated based on a Probability of Default/Loss Given Default (“PD/LGD”) basis taking into consideration the expected life of each security. Held to maturity securities which are issued by the United States of America (“U.S.”) or are guaranteed by U.S. federal agencies do not currently have an allowance for credit loss as the Company determined these securities are either backed by the full faith and credit of the U.S. government and/or there is an unconditional commitment to make interest payments and to return the principal investment in full to investors when a debt security reaches maturity. The Company will evaluate this position no less than annually, however, certain items which may cause the Company to change this methodology include legislative changes that remove a government-sponsored enterprise’s (“GSE”) ability to draw funds from the U.S. government, or legislative changes to housing policy that reduce or eliminate the U.S. government’s implicit guarantee on such securities. For securities which are not U.S. treasury or agency backed, risk ratings are generally sourced from Moody’s or Standard & Poor’s. The Company updates loss given default, probability of default, and recovery rates for each security as that information becomes available but no less than annually. The expected remaining life to maturity of each applicable security is updated quarterly. Any expected credit losses on held to maturity securities would be presented as an allowance rather than as a direct write-down through the consolidated statements of income if the Company does not intend to sell or believes that it is more likely than not that the Company will be required to sell the security. Allowance for Credit Losses - Available for Sale Securities The Company measures expected credit losses on available for sale securities based upon the gain or loss position of the security. For available for sale debt securities in an unrealized loss position, which the Company does not intend to sell, or it is not more likely than not that the Company will be required to sell the security before recovery of the Company’s amortized cost, the Company evaluates qualitative criteria to determine any expected loss. This includes among other items the financial health of, and specific prospects for the issuer, including whether the issuer is in compliance with the terms and covenants of the security. The Company also evaluates quantitative criteria including determining whether there has been an adverse change in expected future cash flows of the security. If the Company does not expect to recover the entire amortized cost basis of the security, an allowance for credit losses would be recorded, with a related charge to earnings, limited by the amount of the fair value of the security less its amortized cost. If the Company intends to sell the security or it is more likely than not that the Company will be required to sell the debt security before recovery of its amortized cost basis, the Company recognizes the entire difference between the security’s amortized cost basis and its fair value in earnings.
Loans	Loans Loans are reported at the amount of their outstanding principal, including deferred loan origination fees and costs, reduced by unearned discounts, and the allowance for credit losses. Loans are considered delinquent when a payment of principal and/or interest becomes past due 30 days following its scheduled payment due date. Loans on which the accrual of interest has been discontinued are designated as non-accrual loans. Loans are removed from non-accrual when they become less than 90 days past due and when concern no longer exists as to the collectability of principal or interest. Allowance for Credit Losses - Loans Losses on loan receivables are estimated and recognized upon origination of the loan, based on expected credit losses for the life of the loan balance as of the period end date. The Company’s methodology for calculating the allowance for credit losses (“ACL”) on loans consists of quantitative and qualitative components. The Company uses a discounted cash flow method incorporating probability of default and loss given default forecasted based on statistically derived economic variable loss drivers combined with qualitative factors, to estimate expected credit losses. This process includes estimates which involve modeling loss projections attributable to existing loan balances, considering historical experience, current conditions, and future expectations for homogeneous pools of loans over the reasonable and supportable forecast period. The reasonable and supportable forecast period is determined based upon the accuracy level of historical loss forecast estimates, the specific loan level models and methodology utilized, and considers material changes in growth and credit strategy, and business changes. For periods beyond a reasonable and supportable forecast interval, the Company reverts to historical information over a period for which comparable data is available. The historical information either experienced by the Company, or by a selection of peer banks when appropriate, is derived from a combination of recessionary and non-recessionary performance periods for which data is available. Similar to the reasonable and supportable forecast period, the Company reassesses the reversion period at the segment level, considering any required adjustments for differences in underwriting standards, portfolio mix, and other relevant data shifts over time. The Company generally segments its loan receivable population into homogeneous pools of loans. Consistent with the Company’s other assumptions, the Company regularly reviews segmentation to determine whether the homogeneous pools remain relevant as risk characteristics change. When a loan no longer meets the criteria of its initial pooling as a result of credit deterioration or other changes, the Company may evaluate the credit for estimated losses on an individual basis if the Company determines that the credit no longer retains the same risk characteristics. To the extent that there are a multitude of these loans with new similar risk characteristics, the Company would anticipate a change to the pooling methodology. Loans that do not share risk characteristics are evaluated on an individual basis and are not included in the collective evaluation. For loans with real estate collateral, when management determines that foreclosure is probable, expected credit losses are based on the fair value of the collateral at the reporting date, adjusted for selling costs as appropriate. The qualitative component of the ACL considers (i) the uncertainty of forward-looking scenarios; (ii) certain portfolio characteristics, such as portfolio concentrations, real estate values, changes in the number and amount of non-accrual and past due loans; and (iii) model limitations; among other factors. Qualitative adjustments are considered when management believes expected credit losses are not representative of historical loss experience alone, and should be adjusted to reflect the current conditions and characteristics of the Company’s own portfolio. They are made at the segment level, considering any required adjustments for differences in underwriting standards, portfolio mix, and other relevant data shifts over time. The Company evaluates the allowance for credit losses on loans quarterly. The Company regularly reviews its collection experience (including delinquencies and net charge-offs) in determining its allowance for credit losses. The Company also considers its historical loss experience to date based on actual defaulted loans and overall portfolio indicators including delinquent and non-accrual loans, trends in loan volume and lending terms, credit policies and other observable environmental factors such as unemployment and interest rate changes. The underlying assumption estimates and assessments the Company uses to estimate the allowance for credit losses reflects the Company’s best estimate of model assumptions and forecasted conditions at that time. Changes in such estimates can significantly affect the allowance and provision for (release of) credit losses. It is possible and likely that the Company will experience credit losses that are different from the current estimates. The provision for (release of) credit losses charged to income is based on management’s judgment of the amount necessary to maintain the allowance at a level to provide for expected credit losses for the life of the loan balances as of the evaluation date. When management believes that the collectability of a loan’s principal balance, or portions thereof, is unlikely, the principal amount is charged against the allowance for credit losses. Recoveries on loans that have been previously charged off are credited to the allowance for credit losses, generally at the time cash is received on a charged-off account. The allowance is an estimate, and ultimate losses may vary from current estimates. As adjustments become necessary, they are reported in the results of operations through the provision for (release of) credit losses in the period in which they become known. Risk characteristics relevant to each portfolio segment are as follows: Residential mortgage and home equity loans – The Company generally does not originate loans in these segments with a loan-to-value ratio greater than 80 %, unless covered by private mortgage insurance, and in all cases not greater than a loan-to-value ratio of 97 %. The Company does not originate subprime loans. Loans in these segments are secured by one-to-four family residential real estate, and repayment is primarily dependent on the credit quality of the individual borrower. Commercial mortgage loans – This includes multi-family properties and construction. The Company generally does not originate loans in this segment with a loan-to-value ratio greater than 75 % . Loans in this segment are secured by owner-occupied and nonowner-occupied commercial real estate (“CRE”), and repayment is primarily dependent on the cash flows of the property (if nonowner-occupied) or of the business (if owner-occupied). Commercial and industrial loans (“C&I”) – Loans in this segment are made to businesses and are generally secured by equipment, accounts receivable, or inventory, as well as the personal guarantees of the principal owners of the business, and repayment is primarily dependent on the cash flows generated by the business. In addition, this segment includes certain loans issued under the U. S. Small Business Administration’s (“SBA”) Paycheck Protection Program (“PPP”). These loans are guaranteed and are not evaluated for an allowance for credit losses because the Company expects the guarantees will be effective, if necessary. Consumer loans – Loans in this segment are made to individuals and can be secured or unsecured. Repayment is primarily dependent on the credit quality of the individual borrower. The majority of the Company’s loans are concentrated in Eastern Massachusetts and Southern New Hampshire and therefore the overall health of the local economy, including unemployment rates, vacancy rates, and consumer spending levels, can have a material effect on the credit quality of all of these portfolio segments. The process to determine the allowance for credit losses requires management to exercise considerable judgment regarding the risk characteristics of the loan portfolio segments and the effect of relevant internal and external factors. Allowance for Credit Losses - Unfunded Commitments The expected credit losses for unfunded commitments are measured over the contractual period of the Company’s exposure to credit risk. The estimate of credit loss incorporates assumptions for both the likelihood and amount of funding over the estimated life of the commitments, for the risk of loss, and current conditions and expectations. Management periodically reviews and updates its assumptions for estimated funding rates based on historical rates, and factors such as portfolio growth, changes to organizational structure, economic conditions, borrowing habits, or any other factor which could impact the likelihood that funding will occur. The Company does not reserve for unfunded commitments which are unconditionally cancellable. Acquired Loans Acquired loans are recorded at fair value at the date of acquisition based on a discounted cash flow methodology that considers various factors, including the type of loan and related collateral, classification status, fixed or variable interest rate, term of loan and whether or not the loan was amortizing, and a discount rate reflecting the Company’s assessment of risk inherent in the cash flow estimates. Purchased loans are grouped together according to similar risk characteristics and are treated in the aggregate when applying various valuation techniques. These cash flow evaluations are inherently subjective as they may be susceptible to significant change. Effective January 1, 2020, loans acquired in a business combination that have experienced more-than-insignificant deterioration in credit quality since origination are considered purchased credit deteriorated (“PCD”) loans. The Company evaluates acquired loans for deterioration in credit quality based on, but not limited to, the following: (1) non-accrual status; (2) troubled debt restructured designation; (3) risk ratings of special mention, substandard or doubtful; (4) watchlist credits; and (5) delinquency status, including loans that are current on acquisition date, but had been previously delinquent. At the acquisition date, an estimate of expected credit losses is made for groups of PCD loans with similar risk characteristics and individual PCD loans without similar risk characteristics. This initial allowance for credit losses is allocated to individual PCD loans and added to the purchase price or acquisition date fair values to establish the initial amortized cost basis of the PCD loans. As the initial allowance for credit losses is added to the purchase price, there is no credit loss expense recognized upon acquisition of a PCD loan. Any difference between the unpaid principal balance of PCD loans and the amortized cost basis is considered to relate to noncredit factors and results in a discount or premium. Discounts and premiums are recognized through interest income on a level-yield method over the life of the loans. For acquired loans not deemed PCD at acquisition, the differences between the initial fair value and the unpaid principal balance are recognized as interest income on a level-yield basis over the lives of the related loans. At the acquisition date, an initial allowance for expected credit losses is estimated and recorded as provision for credit losses. The subsequent measurement of expected credit losses for all acquired loans is the same as the subsequent measurement of expected credit losses for originated loans. Allowance for Loan Losses Prior to the adoption of ASC Topic 326 – Financial Instruments – Credit Losses (“CECL”) on January 1, 2020, the Company calculated its provision for loan losses and the level of the allowance for loan losses to reflect management’s estimate of probable loan losses inherent in the loan portfolio at the balance sheet date. Management used a systematic process and methodology to establish the allowance for loan losses each quarter. To determine the total allowance for loan losses, an estimate was made by management of the allowance needed for each of the following segments of the loan portfolio: (a) residential mortgage loans, (b) commercial mortgage loans, (c) home equity loans, (d) C&I loans, and (e) consumer loans. Portfolio segments were further disaggregated into classes of loans. The establishment of the allowance for each portfolio segment was based on a process that evaluated the risk characteristics relevant to each portfolio segment and took into consideration multiple internal and external factors. Internal factors included, but were not limited to, (a) historic levels and trends in charge-offs, delinquencies, risk ratings, and foreclosures, (b) level and changes in industry, geographic, and credit concentrations, (c) underwriting policies and adherence to such policies, (d) the growth and vintage of the portfolios, and (e) the experience of, and any changes in, lending and credit personnel. External factors included, but were not limited to, (a) conditions and trends in the local and national economy and (b) levels and trends in national delinquent and non-performing loans. The Company evaluated certain loans individually for specific impairment. A loan was considered impaired when, based on current information and events, it was probable that the Company would be unable to collect the scheduled payments of principal or interest when due according to the contractual terms of the loan agreement. Loans that experienced insignificant payment delays and payment shortfalls generally were not classified as impaired. Loans were selected for evaluation based upon internal risk rating, delinquency status, or non-accrual status. A specific allowance amount was allocated to an individual loan when such loan had been deemed impaired and when the amount of the probable loss was able to be estimated. Estimates of loss were determined by the present value of anticipated future cash flows, the loan’s observable fair market value, or the fair value of the collateral, if the loan was collateral dependent. Loans Held for Sale Residential mortgage loans originated and intended for sale in the secondary market are classified as held for sale at the time of their origination and are carried at the lower of cost or fair value on an individual loan basis. Changes in fair value relating to loans held for sale below the loans cost basis are charged against gain on loans sold. Gains and losses on the actual sale of the residential loans are recorded in earnings as gains on loans sold, net on the consolidated statements of income.
Bank Owned Life Insurance	Bank Owned Life Insurance Bank owned life insurance (“BOLI”) represents life insurance on the lives of certain active and former employees who have provided positive consent allowing the Company to be the beneficiary of such policies. Since the Company is the primary beneficiary of the insurance policies, increases in the cash value of the policies, as well as insurance proceeds received in excess of cash surrender value, are recorded in noninterest income, and are not subject to income taxes. Applicable regulations generally limit the Company’s investment in BOLI to 25 % of its Tier 1 capital plus its allowance for credit losses. The Company reviews the financial strength of the insurance carriers prior to the purchase of BOLI and at least annually thereafter.
Banking Premises and Equipment	Banking Premises and Equipment Land is stated at cost. Buildings, leasehold improvements, and equipment are stated at cost, less accumulated depreciation, and amortization, which is computed using the straight-line method over the estimated useful lives of the assets or the terms of the leases, if shorter. The cost of ordinary maintenance and repairs is charged to expense when incurred.
Leases	Leases The Company leases office space and certain branch locations under noncancelable operating leases, several of which have renewal options to extend lease terms. Upon commencement of a new lease, the Company will recognize a right-of-use (“ROU”) asset and corresponding lease liability. The Company makes the decision on whether to renew an option to extend a lease by considering various factors. The Company will recognize an adjustment to its ROU asset and lease liability when lease agreements are amended and executed. The discount rate used in determining the present value of lease payments is based on the Company’s incremental borrowing rate for borrowings with terms similar to each lease at commencement date. The Company has lease agreements with lease and non-lease components, which are generally accounted for separately. For real estate leases, non-lease components and other non-components, such as common area maintenance charges, real estate taxes, and insurance, are not included in the measurement of the lease liability since they are generally able to be segregated.
Marketing Expense	Marketing Expense Advertising costs are expensed as incurred.
Other Real Estate Owned	Other Real Estate Owned Other real estate owned consists of properties formerly pledged as collateral to loans, which have been acquired by the Company through foreclosure proceedings or acceptance of a deed in lieu of foreclosure. Upon transfer of a loan to foreclosure status, an appraisal is obtained and any excess of the loan balance over the fair value, less estimated costs to sell, is charged against the allowance for credit losses. Expenses and subsequent adjustments to the fair value are treated as noninterest expense through other expenses.
Goodwill, Core Deposit Intangibles, and Other Intangible Assets	Goodwill, Core Deposit Intangibles, and Other Intangible Assets Goodwill represents the excess of the purchase price over the fair value of net assets acquired in a business combination. Core deposit intangible (“CDI”) represents a premium paid to acquire the core deposits of an institution and is recorded as an intangible asset. Goodwill and intangible assets that are not amortized are tested for impairment, based on their fair values, at least annual ly. There was no goodwill impairment recognized during 2022, 2021, or 2020. Identifiable intangible assets that are subject to amortizatio n are also reviewed for impairment based on their fair value. Any impairment is recognized as a charge to earnings and the adjusted carrying amount of the intangible asset becomes its new accounting basis. The remaining useful life of an intangible asset that is being amortized is also evaluated each reporting period to determine whether events and circumstances warrant a revision to the remaining period of amortization. The Company is amortizing the CDI on a straight-line basis over a ten-year period. Mortgage servicing rights (“MSR”) are recognized as separate assets when rights are acquired through purchase or through sale of financial assets with servicing rights retained. The fair value of the servicing rights is determined by estimating the present value of future net cash flows, taking into consideration market loan prepayment speeds, discount rates, servicing costs, and other economic factors. For purposes of measuring impairment, the underlying loans are generally stratified into relatively homogeneous pools based on predominant risk characteristics. Because of the small size of this asset class, and its relative homogeneity, only one stratum is used. I f the aggregate carrying value of the capitalized mortgage servicing rights for this stratum exceeds its fair value, MSR impairment is recognized in earnings through a valuation allowance for the difference. As the loans are repaid and net servicing revenue is earned, the MSR asset is amortized as an offset to loan servicing income. Servicing revenues are expected to exceed this amortization expense. However, if actual prepayment experience or defaults exceed what was originally anticipated, net servicing revenues may be less than expected and mortgage servicing income may be negative.
Income Taxes	Income Taxes The Company and its subsidiaries file income tax returns in the U.S. federal jurisdiction, the Commonwealth of Massachusetts, the state of New Hampshire, the state of Maine, and other states as required. For the tax year ended December 31, 2022, the Company expects to file taxes in Massachusetts, New Hampshire, and Maine. Income taxes are accounted for under the asset and liability method. 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 are adjusted through income tax expenses in the period of enactment. Deferred tax assets are reviewed quarterly and reduced by a valuation allowance if, based upon the information available, it is more likely than not that some or all of the deferred tax assets will not be realized. Interest and penalties related to unrecognized tax benefits, if incurred, are recognized as a component of income tax expense.
Wealth Management Fee Revenue	Wealth Management Fee Revenue The Company earns wealth management fees for providing investment management, trust administration, and financial planning services to clients. The Company’s performance obligation under these contracts is satisfied over time as the wealth management services are provided. Fees are recognized monthly based on the monthly value of the assets under management and the applicable fee rate, or at a fixed annual rate, depending on the terms of the contract. No performance-based incentives are earned on wealth management contracts. The Company also earns trust fees for servicing as trustee for certain clients. As trustee, the Company serves as a fiduciary, administers the client’s trust, and in some cases, manages the assets of the trust. The Company’s performance obligation under these agreements is satisfied over time as the administrative and management services are provided. Fees are recognized monthly based on a percentage of the market value of the account or at a fixed annual rate as outlined in the agreement. The Company also earns fees for trust related activities. The Company’s performance obligation under these agreements is satisfied at a point in time and recognized when these services have been performed. Other Banking Fee Income The Company charges a variety of fees to its clients for services provided on the deposit and deposit management related accounts. Each fee is either transaction-based or assessed monthly. The types of fees include service charges on accounts, wire transfer fees, maintenance fees, ATM fee charges, and other miscellaneous charges related to the accounts. These fees are not governed by individual contracts with clients. They are charged to clients based on disclosures presented to these clients upon opening these accounts, along with updated disclosures when changes are made to the fee structures. The transaction-based fees are recognized in revenue when charged to the client based on specific activity on the client’s account. Monthly service and maintenance charges are recognized in the month they are earned and are charged directly to the client’s account.
Pension and Retirement Plans	Pension and Retirement Plans The Company sponsors a defined benefit pension plan (the “Pension Plan”) and a postretirement health care plan covering substantially all employees hired before May 2, 2011. Effective December 31, 2017, the accrual of benefits for all participants in the Pension Plan was frozen. Benefits for the postretirement health care plan are based on years of service. Expenses for the postretirement health care plan are recognized over the employee’s service life utilizing the projected unit credit actuarial cost method. Effective November 7, 2019, the postretirement health care plan was frozen for employees hired after that date. The Company also sponsors non-qualified retirement programs that provide supplemental retirement benefits to certain current and former executives. Prior to 2016, the Company provided individual non-qualified defined benefit supplemental executive retirement plans (“DB SERPs”) to certain executives. The DB SERPs generally provide for an annual benefit payable in equal monthly installments following the executive’s retirement and continuing for at least the remainder of his or her lifetime, with such annual benefit generally based on the executive’s years of service and his or her highest three consecutive years of base salary and bonus. In 2016, the Company’s Board of Directors discontinued the use of DB SERPs for new entrants to the Company’s non-qualified retirement programs. Instead, new entrants are provided with individual non-qualified defined contribution supplemental executive retirement plans (“DC SERPs”). Under the DC SERPs, the Company may contribute an amount equal to 10 % of the executive’s base salary and bonus to his or her account under the Company’s non-qualified deferred compensation plan, the Executive Deferred Compensation Plan. Expense for the DB SERPs is recognized over the executive’s service life utilizing the projected unit credit actuarial cost method. Expense for the DC SERPs is recognized as incurred. The Company maintains a Profit-Sharing Plan (“PSP”) that provides for deferral of federal and state income taxes on employee contributions allowed under Section 401(k) of federal law. The Company matches employee contributions up to 100 % of the first 4 % of each participant’s salary, eligible bonus, and eligible incentive. Each year, the Company may also make a discretionary contribution to the PSP based on eligible salary, bonus, and incentive. Employees are eligible to participate in the PSP on the first day of their initial date of service. Employees are also eligible to participate in the discretionary contribution portion of the PSP on the first date of their initial date of service. The employee must be employed on the last day of the calendar year or retire at the normal retirement age of 65 during the calendar year to receive the discretionary contribution.
Share-Based Compensation	Share-Based Compensation Share-based compensation plans provide for stock option awards, restricted stock awards, time-based restricted stock units (“RSUs”), and performance-based restricted stock units (“PRSUs”). Compensation expense for restricted stock awards is recognized over the vesting period based on the fair value at the date of grant. RSUs and PRSUs are valued at the fair market value of the Company’s common stock as of the award date. PRSUs’ compensation expense is based on the most recent performance assumption available and is adjusted as assumptions change. If the goals are not met, vesting does not occur, no compensation cost will be recognized and any recognized compensation costs will be reversed. Stock-based awards that do not require future service are expensed in the year of grant.
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities Derivatives are recognized as either assets or liabilities on the consolidated balance sheets and are measured at fair value. The accounting for changes in the fair value of such derivatives depends on the intended use of the derivative and resulting designation. For derivatives not designated as hedges, changes in fair value of the derivative instruments are recognized in earnings in noninterest income. For derivatives designated as fair value hedges, changes in the fair value of such derivatives are recognized in earnings together with the changes in the fair value of the related hedged item. The net amount, if any, represents hedge ineffectiveness and is reflected in earnings. For derivatives designated as cash flow hedges, the effective portion of changes in the fair value of the derivative is recorded in other comprehensive income (loss) and recognized in earnings when the hedged transaction affects earnings. The ineffective portion of changes in the fair value of cash flow hedges is recognized directly in earnings.
Fair Value Measurements	Fair Value Measurements Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The Company measures the fair values of its financial instruments in accordance with accounting guidance that requires an entity to base fair value on exit price and maximize the use of observable inputs and minimize the use of unobservable inputs to determine the exit price. ASC 820, “ Fair Value Measurements and Disclosures” establishes a fair value hierarchy that gives the highest priority to quoted prices in active markets and the lowest priority to unobservable data and requires fair value measurements to be disclosed by level within the hierarchy. The three broad levels defined by the fair value hierarchy are as follows: Level 1 – Quoted prices are available in active markets for identical assets or liabilities as of the reported date. The type of financial instruments included in Level 1 are highly liquid cash instruments with quoted prices such as government or agency securities, listed equities, and money market securities, as well as listed derivative instruments. Level 2 – Pricing inputs are other than quoted prices in active markets, which are either directly or indirectly observable as of the reported date. The nature of these financial instruments includes cash instruments for which quoted prices are available but traded less frequently, derivative instruments whose fair value has been derived using a model where inputs to the model are directly observable in the market or can be derived principally from or corroborated by observable market data, and instruments that are fair valued using other financial instruments, the parameters of which can be directly observed. Instruments which are generally included in this category are corporate bonds and loans, mortgage whole loans, municipal bonds, and over-the-counter derivatives. Level 3 – Instruments that have little to no pricing observability as of the reported date. These financial instruments do not have two-way markets and are measured using management’s best estimate of fair value, where the inputs into the determination of fair value require significant management judgment to estimation. Instruments that are included in this category generally include certain commercial mortgage loans, certain private equity investments, distressed debt, non-investment grade residual interests in securitizations, as well as certain highly structured over-the-counter derivative contracts.
Earnings per Common Share	Earnings per Common Share Earnings per common share is computed using the more dilutive two-class method prescribed under ASC Topic 260, “Earnings Per Share.” ASC Topic 260 provides that unvested share-based payment awards that contain nonforfeitable rights to dividends or dividend equivalents (whether paid or unpaid) are participating securities and shall be included in the computation of earnings per share pursuant to the two-class method. The Company has determined that its outstanding non-vested stock awards are participating securities. Under the two-class method, basic earnings per common share is computed by dividing net earnings allocated to common stock by the weighted-average number of common shares outstanding during the applicable period, excluding outstanding participating securities. Diluted earnings per common share is computed using the weighted-average number of shares determined for the basic earnings per common share computation plus the dilutive effect of common stock equivalents. A reconciliation of the weighted-average shares used in calculating basic earnings per common share and the weighted average common shares used in calculating diluted earnings per common share for the reported periods is provided in Note 20 - Earnings Per Share .
Subsequent Events	Subsequent Events Management has reviewed events occurring through March 16, 2023, the date the consolidated financial statements were issued and determined that no subsequent events occurred requiring adjustment to or disclosure in these consolidated financial statements.
Recently Issued and Adopted Accounting Standards	3. Recently Issued and Adopted Accounting Standards Accounting Pronouncements Adopted in 2022 In December 2022, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2022-06, Reference Rate Reform (Topic 848): Deferral of the Sunset Date of Topic 848. The amendments in this ASU defer the sunset date of Topic 848 from December 31, 2022, to December 31, 2024, after which entities will no longer be permitted to apply the relief in Topic 848. The ASU is effective upon issuance. The FASB had previously issued 2020-04 - Facilitation of the Effects of Reference Rate Reform on Financial Reporting and related amendments in 2020 to ease the potential burden in accounting for reference rate reform. The amendments in ASU 2020-04 were elective and applied to all entities that have contracts, hedging relationships, and other transactions that reference the London Inter-bank Offer Rate (“LIBOR”) or another reference rate expected to be discontinued due to reference rate reform. The adoption of the new ASU did no t have an impact on the Company's consolidated financial statements. Accounting Pronouncements Yet to be Adopted In March 2022, the FASB issued Accounting Standards Update (“ASU”) 2022-02, Financial Instruments – Credit Losses (Topic 326): Troubled Debt Restructurings and Vintage Disclosures. The amendments in this ASU eliminate the accounting guidance for troubled debt restructurings (“TDRs”) by creditors in Subtopic 310-40, Receivables – Troubled Debt Restructurings by Creditors , while enhancing disclosure requirements for certain loan refinancings and restructurings by creditors when a borrower is experiencing financial difficulty. For public business entities, the amendments in this ASU require an entity disclose current-period gross write-offs by year of origination for financing receivables and net investments in leases. This ASU is effective for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. Early adoption was permitted. The Company plans to adopt this guidance in January of 2023. The adoption of the new ASU is not expected to have an impact on the Company's consolidated financial statements. In March 2022, the FASB issued ASU 2022-01, Derivatives and Hedging (Topic 815): Fair Value Hedging - Portfolio Layer Method . The amendments in this ASU allow multiple hedged layers to be designated for a single closed portfolio of financial assets or one or more beneficial interests secured by a portfolio of financial instruments. The amendments in this ASU also clarify the accounting for and promote consistency in the reporting of hedge basis adjustments applicable to both a single hedged layer and multiple hedged layers. These amendments are effective for fiscal years beginning after December 15, 2022, and interim periods within those fiscal years. The adoption of the new ASU is not expected to have an impact on the Compa ny's consolidated financial statements. As of December 31, 2022, the Company has no hedge relationships designated as fair value hedges.

Mergers (Tables)

Mergers (Tables)	12 Months Ended
	Dec. 31, 2022
Business Combinations [Abstract]
Summary of Estimated Fair Value of Assets Acquired and Liabilities Assumed	The following table summarizes the estimated fair value of the assets acquired and liabilities assumed as of the date of the acquisition: At October 1, 2022 Net Assets Acquired at Fair Value (dollars in thousands) Total Purchase Price $ 62,850 Assets Cash and cash equivalents $ 82,174 Investments 22,929 Gross loans 303,215 Allowance for loan loss — Premises and equipment 6,856 Core deposit intangible 5,320 Other assets 8,181 Total assets acquired 428,675 Liabilities Deposits 373,129 Repurchase agreements 3,745 Other liabilities 1,579 Total liabilities assumed 378,453 Net assets acquired $ 50,222 Goodwill $ 12,628
Schedule of Pro forma Financial Information	The following summarizes the pro forma results of operations as if the Company merged with Northmark on January 1, 2022 (2021 amounts represent combined results for the Company and Northmark). The selected pro forma financial information is presented for illustrative purposes only and is not necessarily indicative of the financial results of the combined companies had the acquisition actually been completed at the beginning of the periods presented, nor does it indicate future results for any other interim or full-year period. For the Year Ended December 31, 2022 2021 (dollars in thousands) Net interest and dividend income after provision for loan losses $ 169,606 $ 111,753 Net Income 69,839 29,182

Investment Securities (Tables)

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Summary of Carrying Amounts of Securities and Their Approximate Fair Values	Investment securities have been classified in the accompanying consolidated balance sheets according to management’s intent. The carrying amounts of securities and their approximate fair values were as follows: December 31, 2022 December 31, 2021 Amortized Gross Gross Fair Amortized Gross Gross Fair (dollars in thousands) Available for sale securities U.S. Government Sponsored $ 22,997 $ — $ ( 3,264 ) $ 19,733 $ 22,996 $ 246 $ ( 231 ) $ 23,011 Mortgage-backed securities 158,034 3 ( 25,354 ) 132,683 176,531 959 ( 4,462 ) 173,028 Corporate debt securities 996 4 — 1,000 1,743 24 ( 3 ) 1,764 Total available for sale securities $ 182,027 $ 7 $ ( 28,618 ) $ 153,416 $ 201,270 $ 1,229 $ ( 4,696 ) $ 197,803 Held to maturity securities U.S. Treasury Notes $ 3,970 $ — $ ( 18 ) $ 3,952 $ — $ — $ — $ — Mortgage-backed securities 951,372 4 ( 157,208 ) 794,168 864,983 3,981 ( 13,258 ) 855,706 Corporate debt securities 250 — ( 6 ) 244 6,997 26 — 7,023 Municipal securities 96,405 88 ( 9,271 ) 87,222 105,081 3,798 ( 516 ) 108,363 Total held to maturity securities $ 1,051,997 $ 92 $ ( 166,503 ) $ 885,586 $ 977,061 $ 7,805 $ ( 13,774 ) $ 971,092 Total $ 1,234,024 $ 99 $ ( 195,121 ) $ 1,039,002 $ 1,178,331 $ 9,034 $ ( 18,470 ) $ 1,168,895
Schedule of Amortized Cost and Fair Value of Investment Securities, Aggregated By Earlier of Guaranteed Call Date or Contractual Maturity	The amortized cost and fair value of investment securities, aggregated by the contractual maturity, are shown below. Municipal securities are aggregated by the earliest of call date or contractual maturity. Maturities of mortgage-backed securities do not take into consideration scheduled amortization or prepayments. Actual maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties. December 31, 2022 Within One Year After One, But After Five, But After Ten Years Total Amortized Fair Amortized Fair Amortized Fair Amortized Fair Amortized Fair (dollars in thousands) Available for sale securities U.S. Government Sponsored Enterprise obligations $ — $ — $ 9,997 $ 9,012 $ 5,000 $ 4,346 $ 8,000 $ 6,375 $ 22,997 $ 19,733 Mortgage-backed securities — — 10,680 9,966 41,622 34,934 105,732 87,783 158,034 132,683 Corporate debt securities 996 1,000 — — — — — — 996 1,000 Total available for sale securities $ 996 $ 1,000 $ 20,677 $ 18,978 $ 46,622 $ 39,280 $ 113,732 $ 94,158 $ 182,027 $ 153,416 Held to maturity securities U.S. Treasury Notes $ 987 $ 983 $ 2,983 $ 2,969 $ — $ — $ — $ — $ 3,970 $ 3,952 Mortgage-backed securities — — 19,572 18,355 48,731 42,866 883,069 732,947 951,372 794,168 Corporate debt securities — — 250 244 — — — — 250 244 Municipal securities 6,987 6,997 18,657 18,602 26,441 26,028 44,320 35,595 96,405 87,222 Total held to maturity securities $ 7,974 $ 7,980 $ 41,462 $ 40,170 $ 75,172 $ 68,894 $ 927,389 $ 768,542 $ 1,051,997 $ 885,586 Total $ 8,970 $ 8,980 $ 62,139 $ 59,148 $ 121,794 $ 108,174 $ 1,041,121 $ 862,700 $ 1,234,024 $ 1,039,002
Gross Unrealized Losses of Aggregated by Investment Category and Length of Time that Individual Investment Securities have been in Continuous Loss Position	The following tables show the Company’s investment securities with gross unrealized losses, for which an allowance for credit losses has not been recorded at December 31, 2022 or at December 31, 2021, aggregated by investment category and length of time that individual investment securities have been in a continuous loss position: December 31, 2022 Less than 12 months 12 months or longer Total Fair Unrealized Fair Unrealized Fair Unrealized (dollars in thousands) Available for sale securities U.S. Government Sponsored Enterprise $ 10,722 $ ( 2,278 ) $ 9,012 $ ( 986 ) $ 19,734 $ ( 3,264 ) Mortgage-backed securities 41,832 ( 3,097 ) 90,545 ( 22,257 ) 132,377 ( 25,354 ) Total available for sale securities $ 52,554 $ ( 5,375 ) $ 99,557 $ ( 23,243 ) $ 152,111 $ ( 28,618 ) Held to maturity securities U.S. Treasury Notes $ 3,952 $ ( 18 ) $ — $ — $ 3,952 $ ( 18 ) Mortgage-backed securities 230,708 ( 22,362 ) 562,835 ( 134,846 ) 793,543 ( 157,208 ) Corporate debt securities 243 ( 6 ) — — 243 ( 6 ) Municipal securities 51,969 ( 4,388 ) 13,714 ( 4,883 ) 65,683 ( 9,271 ) Total held to maturity securities $ 286,872 $ ( 26,774 ) $ 576,549 $ ( 139,729 ) $ 863,421 $ ( 166,503 ) Total $ 339,426 $ ( 32,149 ) $ 676,106 $ ( 162,972 ) $ 1,015,532 $ ( 195,121 ) December 31, 2021 Less than 12 months 12 months or longer Total Fair Unrealized Fair Unrealized Fair Unrealized (dollars in thousands) Available for sale securities U.S. Government Sponsored Enterprise $ 4,881 $ ( 115 ) $ 4,884 $ ( 116 ) $ 9,765 $ ( 231 ) Mortgage-backed securities 74,724 ( 2,253 ) 47,871 ( 2,209 ) 122,595 ( 4,462 ) Corporate debt securities 760 ( 3 ) — — 760 ( 3 ) Total available for sale securities $ 80,365 $ ( 2,371 ) $ 52,755 $ ( 2,325 ) $ 133,120 $ ( 4,696 ) Held to maturity securities Mortgage-backed securities $ 740,966 $ ( 12,509 ) $ 15,345 $ ( 749 ) $ 756,311 $ ( 13,258 ) Municipal securities 12,607 ( 194 ) 5,716 ( 322 ) 18,323 ( 516 ) Total held to maturity securities $ 753,573 $ ( 12,703 ) $ 21,061 $ ( 1,071 ) $ 774,634 $ ( 13,774 ) Total $ 833,938 $ ( 15,074 ) $ 73,816 $ ( 3,396 ) $ 907,754 $ ( 18,470 )
Summary of Gains (Losses) from Sale of Investment Securities	The following table sets forth information regarding sales of investment securities and the resulting gains or losses from such sales: For the Year Ended December 31, 2022 2021 2020 (dollars in thousands) Amortized cost of securities sold $ 19,018 $ — $ 10,752 Gross gains realized on securities sold — — 111 Gross losses realized on securities sold — — ( 42 ) Net proceeds from securities sold $ 19,018 $ — $ 10,821
Summary of Credit Rating of Debt Securities Portfolio	The following tables summarize the credit rating of the Company’s debt securities portfolio at December 31, 2022 and December 31, 2021. December 31, 2022 Mortgage-backed Securities (1) Corporate Debt Securities Municipal Securities U.S. GSE Obligations U.S. Treasury Notes Total (dollars in thousands) Available for sale securities, at fair value AAA/AA/A $ 132,683 $ — $ — $ 19,733 $ — $ 152,416 BBB/BB/B — 1,000 — — — 1,000 Total available for sale securities $ 132,683 $ 1,000 $ — $ 19,733 $ — $ 153,416 Held to maturity securities, at amortized cost AAA/AA/A $ 951,372 $ 250 $ 96,405 $ — $ 3,970 $ 1,051,997 Total held to maturity securities $ 951,372 $ 250 $ 96,405 $ — $ 3,970 $ 1,051,997 December 31, 2021 Mortgage-backed Securities (1) Corporate Debt Securities Municipal Securities U.S. GSE Obligations Total (dollars in thousands) Available for sale securities, at fair value AAA/AA/A $ 173,028 $ 759 $ — $ 23,011 $ 196,798 BBB/BB/B — 1,005 — — 1,005 Total available for sale securities $ 173,028 $ 1,764 $ — $ 23,011 $ 197,803 Held to maturity securities, at amortized cost AAA/AA/A $ 864,983 $ 6,997 $ 105,081 $ — $ 977,061 Total held to maturity securities $ 864,983 $ 6,997 $ 105,081 $ — $ 977,061 1. Includes Agency mortgage-backed pass-through securities and collateralized mortgage obligations issued by U.S. Government Sponsored enterprises ("GSEs") and U.S. government agencies, such as FNMA, FHLMC, and GNMA that are not rated by Moody’s or Standard & Poor's. Each security contains a guarantee by the issuing GSE or agency and therefore carries an implicit guarantee of the U.S. government. These have been categorized as AAA/AA/A.

Loans and Allowance for Credi_2

Loans and Allowance for Credit Losses (Tables)	12 Months Ended
	Dec. 31, 2022
Receivables [Abstract]
Loans Outstanding by Category	Loans outstanding are detailed by category as follows: December 31, 2022 December 31, 2021 (dollars in thousands) Residential mortgage Mortgages - fixed rate $ 902,968 $ 716,456 Mortgages - adjustable rate 703,958 679,675 Construction 35,299 13,012 Deferred costs, net of unearned fees 6,613 5,936 Total residential mortgages 1,648,838 1,415,079 Commercial mortgage Mortgages - non-owner occupied 1,592,732 1,272,135 Mortgages - owner occupied 183,591 150,632 Construction 135,782 86,246 Deferred costs, net of unearned fees 2,318 1,989 Total commercial mortgages 1,914,423 1,511,002 Home equity Home equity - lines of credit 108,961 85,639 Home equity - term loans 2,098 2,017 Deferred costs, net of unearned fees 292 304 Total home equity 111,351 87,960 Commercial and industrial Commercial and industrial 349,026 247,024 PPP loans 1,384 22,856 Unearned fees, net of deferred costs 240 ( 434 ) Total commercial and industrial 350,650 269,446 Consumer Secured 35,679 34,308 Unsecured 1,897 1,303 Deferred costs, net of unearned fees 18 8 Total consumer 37,594 35,619 Total loans $ 4,062,856 $ 3,319,106
Non-performing Loans Disaggregated by Loan Category	The following tables set forth information regarding non-performing loans disaggregated by loan category: December 31, 2022 Residential Commercial Home Commercial and Total (dollars in thousands) Non-performing loans: Non-accrual loans $ 4,733 $ 311 $ 722 $ 73 $ 5,839 Troubled debt restructurings 622 — — 81 703 Total $ 5,355 $ 311 $ 722 $ 154 $ 6,542 December 31, 2021 Residential Commercial Home Commercial and Total (dollars in thousands) Non-performing loans: Non-accrual loans $ 3,777 $ 517 $ 223 $ 111 $ 4,628 Troubled debt restructurings 652 — — 106 758 Total $ 4,429 $ 517 $ 223 $ 217 $ 5,386
Loans Receivable Disaggregated by Credit Quality Indicator	The following tables contain period-end balances of loans receivable disaggregated by credit quality indicator: Credit Quality Indicator - by Origination Year as of December 31, 2022 2022 2021 2020 2019 2018 Prior Revolving loans amortized cost basis Total (dollars in thousands) Residential Mortgage: Current $ 314,599 $ 511,217 $ 276,698 $ 113,251 $ 77,620 $ 350,098 $ — $ 1,643,483 Non-performing — — 206 315 684 4,150 — 5,355 Total $ 314,599 $ 511,217 $ 276,904 $ 113,566 $ 78,304 $ 354,248 $ — $ 1,648,838 Home equity: Current $ 3,611 $ — $ — $ 58 $ 360 $ 481 $ 106,119 $ 110,629 Non-performing — — — — — — 722 722 Total $ 3,611 $ — $ — $ 58 $ 360 $ 481 $ 106,841 $ 111,351 Consumer: Current $ 13,214 $ 8,482 $ 5,353 $ 444 $ 2,078 $ 7,424 $ 599 $ 37,594 Non-performing — — — — — — — — Total $ 13,214 $ 8,482 $ 5,353 $ 444 $ 2,078 $ 7,424 $ 599 $ 37,594 Credit Quality Indicator - by Origination Year as of December 31, 2022 2022 2021 2020 2019 2018 Prior Revolving loans amortized cost basis Total (dollars in thousands) Commercial Mortgage: Credit risk profile by internally 1-6 (Pass) $ 411,927 $ 330,593 $ 222,073 $ 260,588 $ 125,398 $ 489,564 $ — $ 1,840,143 7 (Special Mention) — — 4,562 41,578 21,697 6,132 — 73,969 8 (Substandard) — — — — — 311 — 311 9 (Doubtful) — — — — — — — — 10 (Loss) — — — — — — — — Total $ 411,927 $ 330,593 $ 226,635 $ 302,166 $ 147,095 $ 496,007 $ — $ 1,914,423 Commercial and Industrial: Credit risk profile by internally 1-6 (Pass) $ 128,301 $ 67,727 $ 62,025 $ 28,557 $ 18,794 $ 36,836 $ 475 $ 342,715 7 (Special Mention) — 4,211 130 161 407 121 10 5,040 8 (Substandard) — — 628 2,102 81 84 — 2,895 9 (Doubtful) — — — — — — — — 10 (Loss) — — — — — — — — Total $ 128,301 $ 71,938 $ 62,783 $ 30,820 $ 19,282 $ 37,041 $ 485 $ 350,650 Credit Quality Indicator - by Origination Year as of December 31, 2021 2021 2020 2019 2018 2017 Prior Revolving loans amortized cost basis Total (dollars in thousands) Residential Mortgage: Current $ 535,071 $ 329,501 $ 135,139 $ 101,108 $ 77,702 $ 232,129 $ — $ 1,410,650 Non-performing — 151 — 330 54 3,894 — 4,429 Total $ 535,071 $ 329,652 $ 135,139 $ 101,438 $ 77,756 $ 236,023 $ — $ 1,415,079 Home equity: Current $ — $ 719 $ 3,088 $ 4,469 $ 5,060 $ 5,475 $ 68,926 $ 87,737 Non-performing — — 223 — — — — 223 Total $ — $ 719 $ 3,311 $ 4,469 $ 5,060 $ 5,475 $ 68,926 $ 87,960 Consumer: Current $ 14,427 $ 8,758 $ 1,544 $ 3,168 $ 1,838 $ 5,357 $ 527 $ 35,619 Non-performing — — — — — — — — Total $ 14,427 $ 8,758 $ 1,544 $ 3,168 $ 1,838 $ 5,357 $ 527 $ 35,619 Credit Quality Indicator - by Origination Year as of December 31, 2021 2021 2020 2019 2018 2017 Prior Revolving loans amortized cost basis Total (dollars in thousands) Commercial Mortgage: Credit risk profile by internally 1-6 (Pass) $ 319,633 $ 248,691 $ 320,189 $ 158,462 $ 93,016 $ 298,791 $ — $ 1,438,782 7 (Special Mention) — 1,096 40,879 22,471 2,913 4,131 — 71,490 8 (Substandard) — — — — — 730 — 730 9 (Doubtful) — — — — — — — — 10 (Loss) — — — — — — — — Total $ 319,633 $ 249,787 $ 361,068 $ 180,933 $ 95,929 $ 303,652 $ — $ 1,511,002 Commercial and Industrial: Credit risk profile by internally 1-6 (Pass) $ 83,614 $ 77,073 $ 38,299 $ 34,360 $ 19,727 $ 4,622 $ 353 $ 258,048 7 (Special Mention) 318 350 5,523 406 161 859 10 7,627 8 (Substandard) — 792 2,331 504 — 144 — 3,771 9 (Doubtful) — — — — — — — — 10 (Loss) — — — — — — — — Total $ 83,932 $ 78,215 $ 46,153 $ 35,270 $ 19,888 $ 5,625 $ 363 $ 269,446
Schedule of Loans Receivable Disaggregated by Past Due Status	The following tables contain period-end balances of loans receivable disaggregated by past due status: December 31, 2022 30-59 Days 60-89 Days 90 Days or greater Total Past Due Current Loans Total (dollars in thousands) Residential mortgage $ 11,359 $ 1,454 $ 1,809 $ 14,622 $ 1,634,216 $ 1,648,838 Commercial mortgage — — — — 1,914,423 1,914,423 Home equity 962 393 214 1,569 109,782 111,351 Commercial and industrial 65 269 — 334 350,316 350,650 Consumer 81 — — 81 37,513 37,594 Total $ 12,467 $ 2,116 $ 2,023 $ 16,606 $ 4,046,250 $ 4,062,856 December 31, 2021 30-59 Days 60-89 Days 90 Days Total Current Total (dollars in thousands) Residential mortgage $ 8,470 $ 415 $ 1,488 $ 10,373 $ 1,404,706 $ 1,415,079 Commercial mortgage 476 — — 476 1,510,526 1,511,002 Home equity 314 643 — 957 87,003 87,960 Commercial and industrial 5 437 — 442 269,004 269,446 Consumer — — — — 35,619 35,619 Total $ 9,265 $ 1,495 $ 1,488 $ 12,248 $ 3,306,858 $ 3,319,106 There were no loans 90 days or more past due and still accruing at December 31, 2022 or December 31, 2021.
Summary of Changes in Allowance for Credit Losses Disaggregated by Loan Category	The following tables contain changes in the allowance for credit losses disaggregated by loan category: For the Year Ended December 31, 2022 Residential Commercial Home Commercial & Consumer Unfunded Commitments Total (dollars in thousands) Allowance for credit loss: Allowance for credit losses - loan Balance at December 31, 2021 $ 13,383 $ 17,133 $ 406 $ 2,989 $ 585 $ — $ 34,496 Provision for acquired loans 527 1,337 117 113 8 — 2,102 Initial allowance for PCD 19 37 — — — — 56 Charge-offs — — — ( 23 ) ( 29 ) — ( 52 ) Recoveries 4 — — 89 12 — 105 Provision for (release of) credit ( 612 ) 579 50 985 65 — 1,067 Allowance for credit losses - loan portfolio $ 13,321 $ 19,086 $ 573 $ 4,153 $ 641 $ — $ 37,774 Allowance for credit losses - Balance at December 31, 2021 $ — $ — $ — $ — $ — $ 1,384 $ 1,384 Acquired loan commitments — — — — — 137 137 Provision for (release of) credit — — — — — 575 575 Allowance for credit losses- $ — $ — $ — $ — $ — $ 2,096 $ 2,096 Total allowance for credit loss $ 13,321 $ 19,086 $ 573 $ 4,153 $ 641 $ 2,096 $ 39,870 For the Year Ended December 31, 2021 Residential Commercial Home Commercial & Consumer Unfunded Commitments Total (dollars in thousands) Allowance for credit loss: Allowance for credit losses - loan portfolio: Balance at December 31, 2020 $ 13,067 $ 18,564 $ 552 $ 3,309 $ 524 $ — $ 36,016 Charge-offs ( 4 ) — — ( 41 ) ( 42 ) — ( 87 ) Recoveries — 30 — 181 30 — 241 Provision for (release of) credit 320 ( 1,461 ) ( 146 ) ( 460 ) 73 — ( 1,674 ) Allowance for credit losses - loan portfolio $ 13,383 $ 17,133 $ 406 $ 2,989 $ 585 $ — $ 34,496 Allowance for credit losses - unfunded commitments: Balance at December 31, 2020 $ — $ — $ — $ — $ — $ 1,004 $ 1,004 Provision for credit — — — — — 380 380 Allowance for credit losses-unfunded commitments — — — — — 1,384 1,384 Total allowance for credit loss $ 13,383 $ 17,133 $ 406 $ 2,989 $ 585 $ 1,384 $ 35,880

Banking Premises and Equipment

Banking Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Summary of Cost and Accumulated Depreciation and Amortization of Property, Leasehold Improvements and Equipment	A summary of the cost and accumulated depreciation and amortization of property, leasehold improvements, and equipment is presented below: December 31, Estimated 2022 2021 Useful Lives (dollars in thousands) Land $ 3,396 $ 1,516 Building and leasehold improvements 25,588 20,254 3 - 30 years Equipment, including vaults 20,165 18,592 3 - 20 years Work in process 22 19 Subtotal 49,171 40,381 Accumulated depreciation and amortization ( 25,874 ) ( 23,055 ) Total $ 23,297 $ 17,326

Intangible Assets (Tables)

Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2022
Schedule of Mortgage Servicing Rights	The following table provides an analysis of mortgage servicing rights, which are included in other assets: Mortgage Valuation Total (dollars in thousands) Balance at December 31, 2019 $ 1,347 $ ( 26 ) $ 1,321 Mortgage servicing rights acquired as a result of the Wellesley merger 50 — 50 Mortgage servicing rights capitalized 536 — 536 Amortization charged against servicing income ( 572 ) — ( 572 ) Change in impairment reserve — ( 116 ) ( 116 ) Balance at December 31, 2020 $ 1,361 $ ( 142 ) $ 1,219 Balance at December 31, 2020 $ 1,361 $ ( 142 ) $ 1,219 Mortgage servicing rights capitalized 281 — 281 Amortization charged against servicing income ( 559 ) — ( 559 ) Change in impairment reserve — 142 142 Balance at December 31, 2021 $ 1,083 $ — $ 1,083 Balance at December 31, 2021 $ 1,083 $ — $ 1,083 Mortgage servicing rights acquired as a result of the Northmark merger 785 785 Mortgage servicing rights capitalized 71 — 71 Amortization charged against servicing income ( 274 ) — ( 274 ) Change in impairment reserve — — — Balance at December 31, 2022 $ 1,665 $ — $ 1,665
Mortgage Servicing Rights
Schedule of Aggregate Estimated Future Amortization Expense	The estimated aggregate future amortization expense for mortgage servicing rights for each of the next five years and thereafter is as follows: Future Amortization Expense (dollars in thousands) 2023 $ 217 2024 192 2025 170 2026 150 2027 132 Thereafter 804 Total $ 1,665

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2022
Deposits [Abstract]
Summary of Deposits	Deposits are summarized as follows: December 31, 2022 December 31, 2021 (dollars in thousands) Demand deposits (non-interest bearing) $ 1,366,395 $ 1,393,935 Interest bearing checking 908,961 763,188 Money market 1,162,773 1,104,238 Savings 790,628 907,722 Retail certificates of deposit under $250,000 117,532 99,196 Retail certificates of deposit $250,000 or greater 87,528 60,171 Brokered certificates of deposit 381,559 2,702 Total deposits $ 4,815,376 $ 4,331,152
Scheduled Maturities of Certificates of Deposits	Certificates of deposit had the following schedule of maturities: December 31, 2022 December 31, 2021 (dollars in thousands) 2022 $ — $ 132,212 2023 533,513 19,062 2024 39,753 4,443 2025 5,377 2,182 2026 6,021 4,170 2027 and after 1,955 — Total certificates of deposit $ 586,619 $ 162,069

Borrowings (Tables)

Borrowings (Tables)	12 Months Ended
	Dec. 31, 2022
Debt Disclosure [Abstract]
Schedule of Information Relating to Long-term Borrowings from FHLB of Boston	Information relating to long-term borrowings from the FHLB of Boston is presented below: December 31, 2022 December 31, 2021 Amount Rate Amount Rate Stated Maturity (dollars in thousands) 2022 $ — — $ 221 1.84 % 2023* 176 2.36 16,221 3.69 $ 176 2.36 % $ 16,442 3.67 % * December 31, 2021 totals includes a $ 15 million advance with an interest rate of 3.80 %, that was callable by the FHLB of Boston on January 27, 2022 .

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Components of Income Tax Expense	The components of income tax expense were as follows: For the Year Ended December 31, 2022 2021 2020 (dollars in thousands) Current tax expense Federal $ 12,906 $ 11,330 $ 7,877 State 5,559 4,862 4,192 18,465 16,192 12,069 Deferred tax expense (benefit) Federal 455 1,840 ( 250 ) State 132 1,059 ( 415 ) 587 2,899 ( 665 ) Total income tax expense $ 19,052 $ 19,091 $ 11,404
Reconciliation of Total Income Tax Expense, Calculated at Statutory Federal Income Tax Expense in Consolidated Statements of Income	The following is a reconciliation of the total income tax expense, calculated at statutory federal income tax rates, to the income tax provision in the consolidated statements of income: For the Year Ended December 31, 2022 2021 2020 (dollars in thousands) Income tax expense at statutory rate of 21.0 % $ 15,112 $ 15,354 $ 9,106 Increase/(decrease) resulting from: State tax, net of federal tax benefit 4,496 4,678 2,984 Tax-exempt income ( 814 ) ( 795 ) ( 694 ) ESOP dividends ( 150 ) ( 145 ) ( 125 ) Bank owned life insurance ( 133 ) ( 165 ) ( 157 ) Compensation limited under 162(m) 193 226 511 Benefit from stock compensation ( 81 ) ( 46 ) — Non-deductible acquisition costs 182 — 186 Non-deductible expenses 44 55 — Impact of CARES Act — — ( 539 ) BOLI surrender, death benefit 310 — — Other ( 107 ) ( 71 ) 132 Total income tax expense $ 19,052 $ 19,091 $ 11,404
Summary of Net Deferred Tax Asset	The Company’s 2022 and 2021 net deferred tax assets were measured using a 27.95 % and 27.92 % tax rate, respectively, and consisted of the following components: December 31, 2022 December 31, 2021 (dollars in thousands) Gross deferred tax assets Allowance for credit losses $ 11,142 $ 10,019 Unrealized losses on available for sale securities 7,390 982 Incentive compensation 1,819 1,905 Equity based compensation 1,298 1,347 Lease liabilities 7,661 9,458 ESOP dividends 200 193 Intangibles and fair value marks (merger related) 2,322 658 Other 931 265 Total gross deferred tax assets 32,763 24,827 Gross deferred tax liabilities Deferred loan origination costs ( 2,886 ) ( 2,324 ) Retirement benefits ( 1,745 ) ( 535 ) Depreciation of premises and equipment ( 2,551 ) ( 1,997 ) Right-of-use asset ( 7,014 ) ( 8,733 ) Mortgage servicing rights ( 465 ) ( 303 ) Goodwill ( 115 ) ( 115 ) Derivative transactions 3 ( 835 ) Total gross deferred tax liabilities ( 14,773 ) ( 14,842 ) Net deferred tax asset $ 17,990 $ 9,985

Pension and Retirement Plans (T

Pension and Retirement Plans (Tables)	12 Months Ended
	Dec. 31, 2022
Retirement Benefits [Abstract]
Components of Projected Benefit Obligations and Funded Status	Projected benefit obligations and funded status were as follows: Pension Plan Supplemental 2022 2021 2022 2021 (dollars in thousands) Change in projected benefit obligation Obligation at beginning of year $ 47,875 $ 50,117 $ 10,075 $ 10,505 Service cost — — 399 400 Interest cost 1,309 1,211 260 223 Actuarial (gain) loss ( 11,754 ) ( 1,838 ) ( 2,057 ) ( 451 ) Benefits paid ( 1,832 ) ( 1,615 ) ( 617 ) ( 602 ) Obligation at end of year 35,598 47,875 8,060 10,075 Change in plan assets Fair value at beginning of year 60,638 55,802 — — Actual return on plan assets ( 8,457 ) 6,451 — — Employer contribution — — 617 602 Benefits paid ( 1,832 ) ( 1,615 ) ( 617 ) ( 602 ) Fair value at end of year 50,349 60,638 — — Funded status at end of year $ 14,751 $ 12,763 $ ( 8,060 ) $ ( 10,075 )
Schedule of Accumulated Benefit Obligation	Pension Plan Supplemental 2022 2021 2022 2021 (dollars in thousands) Accumulated benefit obligation $ 35,598 $ 47,875 $ 7,627 $ 9,472
Schedule of Amounts Recognized in Accumulated Other Comprehensive Income (Loss)	Amounts recognized in accumulated other comprehensive income (loss) consisted of: Pension Plan Supplemental 2022 2021 2022 2021 (dollars in thousands) Net actuarial (gain) loss $ 373 $ ( 206 ) $ ( 617 ) $ 1,468 Prior service credit — — — — Total $ 373 $ ( 206 ) $ ( 617 ) $ 1,468
Components of Net Periodic Benefit Cost and Amounts Recognized in Other Comprehensive Income/ (Loss)	The components of net periodic benefit cost and amounts recognized in other comprehensive income (loss) were as follows: Pension Plan Supplemental 2022 2021 2022 2021 (dollars in thousands) Net periodic benefit cost Service cost $ — $ — $ 399 $ 400 Interest cost 1,309 1,211 260 223 Expected return on assets ( 3,876 ) ( 3,566 ) — — Amortization of prior service credit — ( 3 ) — — Amortization of net actuarial loss — — 28 40 Net periodic expense (benefit) ( 2,567 ) ( 2,358 ) 687 663 Amounts recognized in other comprehensive income (loss) Net actuarial loss/(gain) 579 ( 4,723 ) ( 2,057 ) ( 451 ) Amortization of prior service credit — 3 — — Amortization of net actuarial loss — — ( 28 ) ( 40 ) Total recognized in other comprehensive income (loss) 579 ( 4,720 ) ( 2,085 ) ( 491 ) Total recognized in net periodic expense (benefit) and other $ ( 1,988 ) $ ( 7,078 ) $ ( 1,398 ) $ 172
Schedule of Weighted-average Assumptions Used to Determine Projected Benefit Obligations and Net Periodic Benefit Cost	Weighted-average assumptions used to determine projected benefit obligations are as follows: Pension Plan Supplemental 2022 2021 2022 2021 Discount rate 5.22 % 2.79 % 5.15 % 2.63 % Rate of compensation increase N/A N/A 4.00 % 4.00 % Weighted-average assumptions used to determine the net periodic benefit cost in each year were as follows: Pension Plan Supplemental 2022 2021 2022 2021 Discount rate 2.79 % 2.45 % 2.63 % 2.21 % Expected long-term return on plan assets 6.50 % 6.50 % N/A N/A Rate of compensation increase N/A N/A 4.00 % 4.00 %
Schedule of Pension Plan Weighted-average Asset Allocations by Asset	The Company’s Pension Plan weighted-average asset allocations by asset category were as follows: December 31, 2022 2021 Equity securities 60 % 68 % Debt securities 33 29 Other — — Cash and equivalents 7 3 Total 100 % 100 %
Summary of Various Categories of Pension Plan Assets	The following table summarizes the various categories of the Pension Plan’s assets: Fair Value as of December 31, 2022 Level 1 Level 2 Level 3 Total (dollars in thousands) Asset category Cash and cash equivalents $ 3,676 $ — $ — $ 3,676 Fixed income — 12,347 — 12,347 Equity securities Mutual funds Domestic equity 24,201 — — 24,201 International 3,942 — — 3,942 Domestic fixed income 6,183 — — 6,183 Total $ 38,002 $ 12,347 $ — $ 50,349 Fair Value as of December 31, 2021 Level 1 Level 2 Level 3 Total (dollars in thousands) Asset category Cash and cash equivalents $ 1,689 $ — $ — $ 1,689 Fixed income — 13,338 — 13,338 Equity securities Common stock Large cap core 16,940 — — 16,940 Small cap core 2,359 — — 2,359 Mutual funds Domestic equity 10,413 — — 10,413 International 6,579 — — 6,579 Domestic fixed income 9,320 — — 9,320 Total $ 47,300 $ 13,338 $ — $ 60,638
Schedule of Benefits Expected to be Paid in the Next Ten Years	Benefits expected to be paid in the next ten years are as follows: Pension Supplemental Postretirement Total (dollars in thousands) Year-ended December 31, 2023 $ 2,124 $ 611 $ 24 $ 2,759 2024 2,197 606 23 2,826 2025 2,270 602 23 2,895 2026 2,394 597 23 3,014 2027 2,378 592 22 2,992 2028-2032 12,695 3,916 123 16,734 Total $ 24,058 $ 6,924 $ 238 $ 31,220

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2022
Summary of Non-vested Restricted Shares Outstanding	A summary of restricted stock outstanding as of December 31, 2022 and 2021, and changes during the years ended on those dates, is presented below: December 31, 2022 December 31, 2021 Number Weighted Number Weighted Restricted stock Non-vested at beginning of year 34,622 $ 78.20 31,649 $ 73.07 Granted 14,380 87.10 18,781 82.06 Vested ( 11,450 ) 76.50 ( 11,691 ) 71.27 Forfeited ( 2,980 ) 81.43 ( 4,117 ) 75.97 Non-vested at end of year 34,572 $ 82.19 34,622 $ 78.20
Schedule of Amounts Recognized in Consolidated Statement of Income for Restricted Stock, Time Based Restricted Stock Units and Performance Based Restricted Stock Units	The following table presents the amounts recognized in the consolidated statements of income for restricted stock, time-based restricted stock units, and performance-based restricted stock units: For the Year Ended December 31, 2022 2021 2020 (dollars in thousands) Share-based compensation expense $ 2,875 $ 3,476 $ 4,923 Related income tax benefit $ 804 $ 970 $ 1,375
Performance-Based Restricted Stock Units
Summary of Non-vested Restricted Stock Units Outstanding	A summary of non-vested performance-based restricted stock units outstanding as of December 31, 2022 and 2021, and changes during the years ended on those dates, is presented below: December 31, 2022 December 31, 2021 Number Weighted Number Weighted Performance-based restricted stock units Non-vested at beginning of year 74,699 $ 73.59 75,246 $ 73.41 Granted 37,263 88.18 32,697 77.00 Vested (Performance achieved) ( 34,248 ) 70.36 ( 30,059 ) 76.56 Forfeited ( 5,580 ) 79.92 ( 3,185 ) 75.06 Non-vested at end of year 72,134 $ 80.83 74,699 $ 73.59
Time Based Restricted Stock Units
Summary of Non-vested Restricted Stock Units Outstanding	A summary of non-vested time-based restricted stock units outstanding as of December 31, 2022 and 2021, and changes during the years ended on those dates, is presented below: December 31, 2022 December 31, 2021 Number Weighted Number Weighted Time-based restricted stock units Non-vested at beginning of year 13,836 $ 75.91 14,968 $ 74.84 Granted 8,796 88.18 7,464 77.00 Vested ( 7,417 ) 75.94 ( 7,899 ) 74.95 Forfeited ( 1,664 ) 84.40 ( 697 ) 75.64 Non-vested at end of year 13,551 $ 82.81 13,836 $ 75.91

Financial Instruments with Of_2

Financial Instruments with Off-Balance-Sheet Risk (Tables)	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Summary of Off-Balance-Sheet Financial Instruments with Contractual Amounts Include Present Credit Risk	Off-balance-sheet financial instruments with contractual amounts that present credit risk included the following: December 31, 2022 December 31, 2021 (dollars in thousands) Financial instruments whose contractual amount represents credit risk: Commitments to extend credit: Unused portion of existing lines of credit $ 1,073,567 $ 809,383 Origination of new loans 25,411 70,633 Standby letters of credit 24,234 18,880 Financial instruments whose notional amount exceeds the amount of credit risk: Commitments to sell residential mortgage loans 250 3,920

Commitment and Contingencies (T

Commitment and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Summary of Components of Operating Lease Cost and Other Related Information	The components of operating lease cost and other related information are as follows: For the Year Ended December 31, 2022 2021 2020 (dollars in thousands) Operating lease cost $ 6,965 $ 6,976 $ 6,691 Variable lease cost (cost excluded from lease payments) 38 13 2 Sublease income ( 316 ) ( 65 ) ( 65 ) Total operating lease cost $ 6,687 $ 6,924 $ 6,628 Other Information Cash paid for amounts included in the measurement of lease liabilities - operating cash flows for operating leases $ 7,263 $ 7,259 $ 6,547 Operating Lease - operating cash flows (liability reduction) 6,401 6,252 5,430 Weighted average lease term - operating leases 5.45 Years 6.13 Years 6.90 Years Weighted average discount rate - operating leases 3.01 % 2.94 % 2.98 %
Schedule of Total Minimum Lease Payments Due in Future Periods under Lease Agreements	The total minimum lease payments due in future periods under these agreements in effect at December 31, 2022 and December 31, 2021 were as follows: Future Minimum December 31, 2022 Lease Payments (dollars in thousands) 2023 $ 7,085 2024 6,085 2025 5,118 2026 3,882 2027 2,079 Thereafter 5,883 Total minimum lease payments $ 30,132 Less: interest ( 2,719 ) Total lease liability $ 27,413

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Schedule of Minimum Capital Requirements Considered Well Capitalized by FRB and FDIC	The Company’s and the Bank’s actual and required capital measures were as follows: Actual Minimum Capital Minimum To Be Amount Ratio Amount Ratio Amount Ratio (dollars in thousands) At December 31, 2022 Cambridge Bancorp: Total capital (to risk-weighted assets) $ 506,239 13.5 % $ 393,285 10.5 % N/A N/A Tier 1 capital (to risk-weighted assets) 466,369 12.5 % 318,373 8.5 % N/A N/A Common equity tier I capital (to risk-weighted assets) 466,369 12.5 % 262,190 7.0 % N/A N/A Tier 1 capital (to average assets) 466,369 8.5 % 219,309 4.0 % N/A N/A Cambridge Trust Company: Total capital (to risk-weighted assets) $ 490,175 13.1 % $ 393,246 10.5 % $ 374,520 10.0 % Tier 1 capital (to risk-weighted assets) 450,305 12.0 % 318,342 8.5 % 299,616 8.0 % Common equity tier I capital (to risk-weighted assets) 450,305 12.0 % 262,164 7.0 % 243,438 6.5 % Tier 1 capital (to average assets) 450,305 8.2 % 219,296 4.0 % 274,120 5.0 % Actual Minimum Capital Minimum To Be Amount Ratio Amount Ratio Amount Ratio (dollars in thousands) At December 31, 2021 Cambridge Bancorp: Total capital (to risk-weighted assets) $ 420,398 13.6 % $ 325,617 10.5 % N/A N/A Tier 1 capital (to risk-weighted assets) 384,518 12.4 % 263,595 8.5 % N/A N/A Common equity tier I capital (to risk-weighted assets) 384,518 12.4 % 217,078 7.0 % N/A N/A Tier 1 capital (to average assets) 384,518 8.3 % 185,015 4.0 % N/A N/A Cambridge Trust Company: Total capital (to risk-weighted assets) $ 409,806 13.2 % $ 325,587 10.5 % $ 310,082 10.0 % Tier 1 capital (to risk-weighted assets) 373,926 12.1 % 263,570 8.5 % 248,066 8.0 % Common equity tier I capital (to risk-weighted assets) 373,926 12.1 % 217,058 7.0 % 201,554 6.5 % Tier 1 capital (to average assets) 373,926 8.1 % 185,003 4.0 % 231,254 5.0 %

Comprehensive Income (Loss) (Ta

Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Summary of Comprehensive Income(Loss)	The Company’s other comprehensive income (loss) consists of unrealized gains or losses on securities held at year-end classified as available for sale and, cash flow hedges, and the component of the unfunded retirement liability computed in accordance with the requirements of ASC Topic 715, “ Compensation – Retirement Benefits. ” The before-tax and after-tax amount of each of these categories, as well as the tax (expense)/benefit of each, is summarized as follows: For the Year Ended For the Year Ended For the Year Ended Before Tax Net-of- Before Tax Net-of- Before Tax Net-of- (dollars in thousands) Available for sale securities Unrealized holding gains (losses) $ ( 25,144 ) $ 6,408 $ ( 18,736 ) $ ( 6,245 ) $ 1,623 $ ( 4,622 ) $ 3,630 $ ( 830 ) $ 2,800 Reclassification adjustment for (gains) losses realized in net income (1) — — — — — — ( 73 ) 16 ( 57 ) Interest rate swaps designated as cash flow hedges Unrealized holding gains (losses) ( 2,170 ) 607 ( 1,563 ) ( 1,329 ) 370 ( 959 ) 6,602 ( 1,844 ) 4,758 Reclassification adjustment for (gains) losses recognized in net income (2) ( 832 ) 232 ( 600 ) ( 2,587 ) 723 ( 1,864 ) ( 1,879 ) 525 ( 1,354 ) Defined benefit retirement plans Net change in retirement liability 1,818 ( 508 ) 1,310 5,273 ( 1,472 ) 3,801 ( 1,695 ) 463 ( 1,232 ) Total other comprehensive income (loss) $ ( 26,328 ) $ 6,739 $ ( 19,589 ) $ ( 4,888 ) $ 1,244 $ ( 3,644 ) $ 6,585 $ ( 1,670 ) $ 4,915 (1) Reported in gain (loss) on disposition of investment securities line item in the Consolidated Statements of Income. (2) Reported in interest on payable loans line item in the Consolidated Statements of Income. The components of accumulated other comprehensive income are as follows: December 31, 2022 December 31, 2021 Before Tax Amount Deferred (tax) benefit Net-of-tax Amount Before Tax Amount Deferred (tax) benefit Net-of-tax Amount (dollars in thousands) Available for sale securities $ ( 28,611 ) $ 7,390 $ ( 21,221 ) $ ( 3,467 ) $ 982 $ ( 2,485 ) Interest Rate swaps designated as cash flow hedges ( 14 ) 4 ( 10 ) 2,988 ( 836 ) 2,152 Defined benefit retirement plans 600 ( 168 ) 432 ( 1,218 ) 341 ( 877 ) Total accumulated other comprehensive income $ ( 28,025 ) $ 7,226 $ ( 20,799 ) $ ( 1,697 ) $ 487 $ ( 1,210 )
Summary of Components of Accumulated Other Comprehensive Income	The components of accumulated other comprehensive income are as follows: December 31, 2022 December 31, 2021 Before Tax Amount Deferred (tax) benefit Net-of-tax Amount Before Tax Amount Deferred (tax) benefit Net-of-tax Amount (dollars in thousands) Available for sale securities $ ( 28,611 ) $ 7,390 $ ( 21,221 ) $ ( 3,467 ) $ 982 $ ( 2,485 ) Interest Rate swaps designated as cash flow hedges ( 14 ) 4 ( 10 ) 2,988 ( 836 ) 2,152 Defined benefit retirement plans 600 ( 168 ) 432 ( 1,218 ) 341 ( 877 ) Total accumulated other comprehensive income $ ( 28,025 ) $ 7,226 $ ( 20,799 ) $ ( 1,697 ) $ 487 $ ( 1,210 )

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2022
Earnings Per Share [Abstract]
Summary of Reconciliation Between Basic and Diluted Earnings Per Share	The following represents a reconciliation between basic and diluted earnings per share: For the Year Ended December 31, 2022 2021 2020 (dollars in thousands, except per share data) Earnings per common share - basic: Numerator: Net income $ 52,909 $ 54,024 $ 31,959 Less dividends and undistributed earnings allocated ( 257 ) ( 250 ) ( 47 ) Net income applicable to common shareholders $ 52,652 $ 53,774 $ 31,912 Denominator: Weighted average common shares outstanding 7,163 6,926 6,289 Earnings per common share - basic $ 7.35 $ 7.76 $ 5.07 Earnings per common share - diluted: Numerator: Net income $ 52,909 $ 54,024 $ 31,959 Less dividends and undistributed earnings allocated ( 257 ) ( 250 ) ( 47 ) Net income applicable to common shareholders $ 52,652 $ 53,774 $ 31,912 Denominator: Weighted average common shares outstanding 7,163 6,926 6,289 Dilutive effect of common stock equivalents 51 65 55 Weighted average diluted common shares outstanding 7,214 6,991 6,344 Earnings per common share - diluted $ 7.30 $ 7.69 $ 5.03

Derivatives And Hedging Activ_2

Derivatives And Hedging Activities (Tables)	12 Months Ended
	Dec. 31, 2022
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of Fair Values of Derivative Instruments in the Company's Consolidated Balance Sheets	The following tables present the notional amount, the location, and fair values of derivative instruments in the Company’s consolidated balance sheets: December 31, 2022 Derivative Assets Derivative Liabilities Notional Amount Balance Sheet Fair Value Notional Amount Balance Sheet Fair Value (dollars in thousands) (dollars in thousands) Derivatives designated as hedging instruments Interest rate contracts $ 250,000 Other Assets $ 1,966 $ — Other Liabilities $ — Total derivatives designated as hedging instruments $ 1,966 $ — Derivatives not designated as hedging instruments Loan related derivative contracts Interest rate contracts $ 499,619 Other Assets $ 50,784 $ 499,619 Other Liabilities $ 50,784 Risk participation agreements-out to counterparties 46,604 Other Assets 23 — Other Liabilities — Risk participation agreements-in with counterparties — Other Assets — 71,046 Other Liabilities 43 Total derivatives not designated as hedging instruments $ 50,807 $ 50,827 December 31, 2021 Derivative Assets Derivative Liabilities Notional Amount Balance Sheet Fair Value Notional Amount Balance Sheet Fair Value (dollars in thousands) (dollars in thousands) Derivatives designated as hedging instruments Interest rate contracts $ 150,000 Other Assets $ 3,513 $ — Other Liabilities $ — Total derivatives designated as hedging instruments $ 3,513 $ — Derivatives not designated as hedging instruments Loan related derivative contracts Interest rate contracts $ 522,581 Other Assets $ 23,431 $ 522,581 Other Liabilities $ 23,431 Risk participation agreements-out to counterparties 47,988 Other Assets 107 — Other Liabilities — Risk participation agreements-in with counterparties — Other Assets — 109,510 Other Liabilities 293 Total derivatives not designated as hedging instruments $ 23,538 $ 23,724
Summary of Cash Flow Hedge Accounting on AOCI	The following tables present the effect of cash flow hedge accounting on AOCI as of the periods presented: Twelve Months Ended December 31, 2022 Amount of Gain or (Loss) Recognized in OCI Amount of Gain or (Loss) Recognized in OCI Included Component Amount of Gain or (Loss) Recognized in OCI Excluded Component Location of Gain or (Loss) Amount of Gain or (Loss) Reclassified from AOCL into Income Amount of Gain or (Loss) Reclassified from AOCL into Income Included Component Amount of Gain or (Loss) Reclassified from AOCL into Income Excluded Component (dollars in thousands) (dollars in thousands) Interest rate contracts $ ( 2,170 ) $ 607 $ ( 1,563 ) Interest Income $ 832 $ 1,026 $ ( 194 ) Twelve Months Ended December 31, 2021 Amount of Gain or (Loss) Recognized in OCI Amount of Gain or (Loss) Recognized in OCI - Included Component Amount of Gain or (Loss) Recognized in OCI - Excluded Component Location of Gain or (Loss) Amount of Gain or (Loss) Reclassified from AOCI into Income Amount of Gain or (Loss) Reclassified from AOCI into Income Included Component Amount of Gain or (Loss) Reclassified from AOCI into Income Excluded Component (dollars in thousands) (dollars in thousands) Interest rate contracts $ ( 1,329 ) $ 370 $ ( 959 ) Interest Income $ 2,587 $ 2,782 $ ( 195 )
Summary of Derivative Financial Instruments Not Designated as Hedging Instruments on the Consolidated Statements of Income	The following table presents the effect of the Company’s derivative financial instruments that are not designated as hedging instruments on the consolidated statements of income as of the periods presented: Amount of Gain or (Loss) Recognized in Income For the Year Ended December 31, 2022 2021 2020 Location of Gain or (Loss) (dollars in thousands) Other contracts Loan-related derivative income $ ( 166 ) $ ( 124 ) $ 155
Schedule of Financial Instruments Eligible for Offset in Consolidated Balance Sheet	The following tables present the information about financial instruments that are eligible for offset in the consolidated balance sheets as of December 31, 2022 and 2021: Gross Amounts Not Offset Gross Amounts Recognized Gross Amounts Offset Net Amounts Recognized Financial Instruments Collateral Pledged (Received) Net Amount December 31, 2022 (dollars in thousands) Offsetting of Derivative Assets Derivative Assets $ 52,773 $ — $ 52,773 $ 48 $ ( 52,130 ) $ 595 Offsetting of Derivative Liabilities Derivative Liabilities $ 50,827 $ — $ 50,827 $ 48 $ — $ 50,875 Gross Amounts Not Offset Gross Amounts Recognized Gross Amounts Offset Net Amounts Recognized Financial Instruments Collateral Pledged (Received) Net Amount December 31, 2021 (dollars in thousands) Offsetting of Derivative Assets Derivative Assets $ 27,051 $ — $ 27,051 $ 6,365 $ — $ 20,686 Offsetting of Derivative Liabilities Derivative Liabilities $ 23,724 $ — $ 23,724 $ 6,365 $ 14,011 $ 3,348

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Summary of Carrying Values and Estimated Fair Values of Financial Instruments	The following is a summary of the carrying values and estimated fair values of the Company’s significant financial instruments as of the dates indicated: December 31, 2022 December 31, 2021 Carrying Estimated Carrying Estimated (dollars in thousands) Financial assets Cash and cash equivalents $ 30,719 $ 30,719 $ 180,153 $ 180,153 Securities available for sale 153,416 153,416 197,803 197,803 Securities held to maturity 1,051,997 885,586 977,061 971,092 Loans, net 4,025,082 3,783,051 3,284,610 3,230,339 Loans held for sale — — 1,490 1,528 FHLB of Boston stock 6,264 6,264 4,816 4,816 Accrued interest receivable 14,118 14,118 9,162 9,162 Mortgage servicing rights 1,665 2,336 1,083 1,518 Interest rate contracts 1,966 1,966 3,513 3,513 Loan level interest rate swaps 50,784 50,784 23,431 23,431 Risk participation agreements out to counterparties 23 23 107 107 Financial liabilities Deposits 4,815,376 4,810,695 4,331,152 4,330,991 Borrowings 105,212 105,202 16,510 16,523 Loan level interest rate swaps 50,784 50,784 23,431 23,431 Risk participation agreements in with counterparties 43 43 293 293
Summary of Certain Assets Reported at Fair Value on a Recurring Basis	The following tables summarize certain assets reported at fair value on a recurring basis: Fair Value as of December 31, 2022 Level 1 Level 2 Level 3 Total (dollars in thousands) Measured on a recurring basis Securities available for sale U.S. GSE obligations $ — $ 19,733 $ — $ 19,733 Mortgage-backed securities — 132,683 — 132,683 Corporate debt securities — 1,000 — 1,000 Other assets Interest rate swaps with clients — 50,784 — 50,784 Risk participation agreements-out to counterparties — 23 — 23 Interest rate contracts — 1,966 — 1,966 Other liabilities Interest rate swaps with counterparties — 50,784 — 18,161 Risk participation agreements-in with counterparties — 43 — 43 Fair Value as of December 31, 2021 Level 1 Level 2 Level 3 Total (dollars in thousands) Measured on a recurring basis Securities available for sale U.S. GSE obligations $ — $ 23,011 $ — $ 23,011 Mortgage-backed securities — 173,028 — 173,028 Corporate debt securities — 1,764 — 1,764 Other assets Interest rate swaps with clients — 23,431 — 23,431 Risk participation agreements-out to counterparties — 107 — 107 Interest rate contracts — 3,513 — 3,513 Other liabilities Interest rate swaps with counterparties — 23,431 — 23,431 Risk participation agreements-in with counterparties — 293 — 293
Schedule of Carrying Value of Assets Measured at Fair Value on a Non-Recurring Basis	The following table presents the carrying value of assets held at December 31, 2022 and 2021, which were measured at fair value on a non-recurring basis: December 31, 2022 Level 1 Level 2 Level 3 Total (dollars in thousands) Items recorded at fair value on a non-recurring basis Assets Individually evaluated collateral dependent loans $ — $ — $ 103 $ 103 Total $ — $ — $ 103 $ 103 December 31, 2021 Level 1 Level 2 Level 3 Total (dollars in thousands) Items recorded at fair value on a non-recurring basis Assets Loans held for sale $ 1,490 $ — $ — $ 1,490 Individually evaluated collateral dependent loans — — 130 130 Total $ 1,490 $ — $ 130 $ 1,620

Condensed Financial Statement_2

Condensed Financial Statements of Parent Company (Tables)	12 Months Ended
	Dec. 31, 2022
Condensed Financial Information Disclosure [Abstract]
Condensed Balance Sheet	Condensed Balance Sheet December 31, 2022 2021 (dollars in thousands) ASSETS Cash and cash equivalents $ 15,747 $ 10,303 Goodwill 33 33 Other assets 318 289 Investment in subsidiary 501,454 427,212 Total assets $ 517,552 $ 437,837 SHAREHOLDERS’ EQUITY Shareholders’ equity $ 517,552 $ 437,837 Total shareholders’ equity $ 517,552 $ 437,837
Condensed Statements of Income	Condensed Statements of Income For the Year Ended December 31, 2022 2021 2020 (dollars in thousands) Income Dividends from subsidiary $ 24,734 $ 25,995 $ 21,639 Total income 24,734 25,995 21,639 Expenses Interest expense — — 444 Other expenses 148 150 110 Total expenses 148 150 554 Income before income taxes and equity in undistributed income of subsidiary 24,586 25,845 21,085 Income tax benefit ( 40 ) ( 42 ) ( 153 ) Income of parent company 24,626 25,887 21,238 Equity in undistributed income of subsidiary 28,283 28,137 10,721 Net income $ 52,909 $ 54,024 $ 31,959
Condensed Statements of Cash Flows	Condensed Statements of Cash Flows For the Year Ended December 31, 2022 2021 2020 (dollars in thousands) CASH FLOWS FROM OPERATING ACTIVITIES: Net income $ 52,909 $ 54,024 $ 31,959 Adjustments to reconcile net income to net cash provided Deferred income tax benefit ( 40 ) ( 42 ) ( 153 ) Change in other assets, net 12 — 3,032 Change in other liabilities, net — 13 444 Undistributed income of subsidiary ( 28,283 ) ( 28,137 ) ( 10,721 ) Net cash provided by operating activities 24,598 25,858 24,561 CASH FLOWS FROM INVESTING ACTIVITIES: Cash paid in business combinations — — ( 534 ) Net cash used in investing activities — — ( 534 ) CASH FLOWS FROM FINANCING ACTIVITIES: Proceeds from the issuance of common stock 580 519 452 Repurchase of common stock ( 1,320 ) ( 1,440 ) ( 556 ) Redemption of subordinate debt — — ( 10,600 ) Cash dividends paid on common stock ( 18,414 ) ( 16,554 ) ( 13,083 ) Net cash provided by/(used in) financing activities ( 19,154 ) ( 17,475 ) ( 23,787 ) Net increase (decrease) in cash 5,444 8,383 240 Cash at beginning of year 10,303 1,920 1,680 Cash at end of year $ 15,747 $ 10,303 $ 1,920 SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION: Significant non-cash transactions Common Stock issued to shareholders due to merger $ 62,850 $ — $ 87,163

The Business - Additional Infor

The Business - Additional Information (Details) - Cambridge Bancorp	12 Months Ended
	Dec. 31, 2022 Corporation Bank Service
Description Of Business [Line Items]
Number of core services | Service	4
Number of wholly owned investment in corporations | Corporation	2
Massachusetts and New Hampshire
Description Of Business [Line Items]
Number of banking office | Bank	22

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2016
Summary Of Significant Accounting Policies [Line Items]
Lessee, operating lease, existence of option to extend	true
Impairment of goodwill recognized	$ 0	$ 0	$ 0
Defined contribution plan, employer matching contribution, percent					10%
Defined benefit pension highest consecutive plan period					3 years
Compensation cost	$ 0
Profit Sharing Plan
Summary Of Significant Accounting Policies [Line Items]
Defined contribution plan, maximum employee contribution, percent				100%
Defined contribution plan, employer matching contribution, percent				4%
Normal retirement age of employees				65 years
Commercial Mortgage
Summary Of Significant Accounting Policies [Line Items]
Percentage of loan to value ratio	75%
Minimum | Residential Mortgage and Home Equity Loans
Summary Of Significant Accounting Policies [Line Items]
Percentage of loan to value ratio	80%
Maximum
Summary Of Significant Accounting Policies [Line Items]
Percentage of bank-owned life insurance	25%
Maximum | Residential Mortgage and Home Equity Loans
Summary Of Significant Accounting Policies [Line Items]
Percentage of loan to value ratio	97%

Recently Issued and Adopted A_2

Recently Issued and Adopted Accounting Standards - Additional Information (Details)	Dec. 31, 2022
ASU 2022-06
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]	true

Mergers - Additional Informatio

Mergers - Additional Information (Details) - USD ($)			12 Months Ended
	Oct. 01, 2022	Jun. 01, 2020	Dec. 31, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
Goodwill			$ 64,539,000	$ 51,912,000
Wellesley Bancorp Inc
Business Acquisition [Line Items]
Business combination, share conversion ratio	0.58%
Total consideration paid		$ 88,800,000
Common stock issued related to merger		1,502,814
Business combination, share price		$ 58
Total assets acquired		$ 985,600,000
Goodwill		20,700,000
Total liabilities assumed		$ 917,600,000
Northmark Bank
Business Acquisition [Line Items]
Number of banking offices	three
Business combination, share conversion ratio	0.995%
Total consideration paid	$ 62,800,000
Common stock issued related to merger	788,137
Business combination, share price	$ 79.74
Merger expenses			1,900,000	$ 0
Business combination, provision for credit losses	$ 2,200,000
Business combination provision for acquired loan			$ 2,200,000
Total assets acquired	428,675,000
Goodwill	12,628,000
Total liabilities assumed	$ 378,453,000

Mergers - Summary of Estimated

Mergers - Summary of Estimated Fair Value of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Oct. 01, 2022	Dec. 31, 2021
Liabilities
Goodwill	$ 64,539		$ 51,912
Northmark Bank
Business Acquisition [Line Items]
Total Purchase Price		$ 62,850
Assets
Cash and cash equivalents		82,174
Investments		22,929
Gross loans		303,215
Allowance for loan loss		0
Premises and equipment		6,856
Core deposit intangible		5,320
Other assets		8,181
Total assets acquired		428,675
Liabilities
Deposits		373,129
Repurchase agreements		3,745
Other liabilities		1,579
Total liabilities assumed		378,453
Net assets acquired		50,222
Goodwill		$ 12,628

Merger - Schedule of Pro forma

Merger - Schedule of Pro forma Financial Information (Details) - Northmark Bank - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net interest and dividend income after provision for loan losses	$ 169,606	$ 111,753
Net Income	$ 69,839	$ 29,182

Cash and Cash Equivalents - Add

Cash and Cash Equivalents - Additional Information (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021
Cash And Cash Equivalents [Line Items]
Cash and cash equivalents	$ 30,719,000	$ 180,153,000
Pledged cash collateral to derivative counterparties	0	13,300,000
Federal Reserve Bank of Boston
Cash And Cash Equivalents [Line Items]
Reserve balance of cash and due from banks	0	0
New Hampshire
Cash And Cash Equivalents [Line Items]
Pledged amount to federal banking department	$ 500,000	$ 500,000

Investment Securities - Summary

Investment Securities - Summary of Carrying Amounts of Securities and Their Approximate Fair Values (Details) - USD ($) $ in Thousands		Dec. 31, 2022	Dec. 31, 2021
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Available for sale securities, Amortized Cost		$ 182,027	$ 201,270
Available for sale securities, Gross Unrealized Gains		7	1,229
Available for sale securities, Gross Unrealized Losses		(28,618)	(4,696)
Total available for sale securities		153,416	197,803
Held to maturity securities, Amortized Cost		1,051,997	977,061
Held to maturity securities, Gross Unrealized Gains		92	7,805
Held to maturity securities, Gross Unrealized Losses		(166,503)	(13,774)
Held-to-maturity securities, fair value		885,586	971,092
Total, Amortized Cost		1,234,024	1,178,331
Total, Gross Unrealized Gains		99	9,034
Total, Gross Unrealized Losses		(195,121)	(18,470)
Total, Fair Value		1,039,002	1,168,895
U.S. Government Sponsored Enterprise Obligations
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Available for sale securities, Amortized Cost		22,997	22,996
Available for sale securities, Gross Unrealized Gains			246
Available for sale securities, Gross Unrealized Losses		(3,264)	(231)
Total available for sale securities		19,733	23,011
U.S. Treasury Notes
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Held to maturity securities, Amortized Cost		3,970
Held to maturity securities, Gross Unrealized Losses		(18)
Held-to-maturity securities, fair value		3,952
Corporate Debt Securities
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Available for sale securities, Amortized Cost		996	1,743
Available for sale securities, Gross Unrealized Gains		4	24
Available for sale securities, Gross Unrealized Losses			(3)
Total available for sale securities		1,000	1,764
Held to maturity securities, Amortized Cost		250	6,997
Held to maturity securities, Gross Unrealized Gains			26
Held to maturity securities, Gross Unrealized Losses		(6)
Held-to-maturity securities, fair value		244	7,023
Mortgage-Backed Securities
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Available for sale securities, Amortized Cost		158,034	176,531
Available for sale securities, Gross Unrealized Gains		3	959
Available for sale securities, Gross Unrealized Losses		(25,354)	(4,462)
Total available for sale securities	[1]	132,683	173,028
Held to maturity securities, Amortized Cost	[1]	951,372	864,983
Held to maturity securities, Gross Unrealized Gains		4	3,981
Held to maturity securities, Gross Unrealized Losses		(157,208)	(13,258)
Held-to-maturity securities, fair value		794,168	855,706
Municipal Securities
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Held to maturity securities, Amortized Cost		96,405	105,081
Held to maturity securities, Gross Unrealized Gains		88	3,798
Held to maturity securities, Gross Unrealized Losses		(9,271)	(516)
Held-to-maturity securities, fair value		$ 87,222	$ 108,363
[1] Includes Agency mortgage-backed pass-through securities and collateralized mortgage obligations issued by U.S. Government Sponsored enterprises ("GSEs") and U.S. government agencies, such as FNMA, FHLMC, and GNMA that are not rated by Moody’s or Standard & Poor's. Each security contains a guarantee by the issuing GSE or agency and therefore carries an implicit guarantee of the U.S. government. These have been categorized as AAA/AA/A.

Investment Securities - Schedul

Investment Securities - Schedule of Amortized Cost and Fair Value of Investment Securities, Aggregated By Earlier of Guaranteed Call Date or Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Available for sale securities, Within One Year, Amortized Cost	$ 996
Available for sale securities, Within One Year, Fair Value	1,000
Available for sale securities, After One, But Within Five Years, Amortized Cost	20,677
Available for sale securities, After One, But Within Five Years, Fair Value	18,978
Available for sale securities, After Five, But Within Ten Years, Amortized Cost	46,622
Available for sale securities, After Five, But Within Ten Years, Fair Value	39,280
Available for sale securities, After Ten Years, Amortized Cost	113,732
Available for sale securities, After Ten Years, Fair Value	94,158
Available for sale securities, Total, Amortized Cost	182,027
Available for sale securities, Total, Fair Value	153,416
Held to maturity securities, Within One Year, Amortized Cost	7,974
Held to maturity securities, Within One Year, Fair Value	7,980
Held to maturity securities, After One, But Within Five Years, Amortized Cost	41,462
Held to maturity securities, After One, But Within Five Years, Fair Value	40,170
Held to maturity securities, After Five, But Within Ten Years, Amortized Cost	75,172
Held to maturity securities, After Five, But Within Ten Years, Fair Value	68,894
Held to maturity securities, After Ten Years, Amortized Cost	927,389
Held to maturity securities, After Ten Years, Fair Value	768,542
Held to maturity securities, Amortized Cost	1,051,997	$ 977,061
Held to maturity securities, Fair Value	885,586	971,092
Available for sale securities and Held to maturity securities, Within One Year, Amortized Cost	8,970
Available for sale securities and Held to maturity securities, Within One Year, Fair Value	8,980
Available for sale securities and Held to maturity securities, After One, But Within Five Years, Amortized Cost	62,139
Available for sale securities and Held to maturity securities, After One, But Within Five Years, Fair Value	59,148
Available for sale securities and Held to maturity securities, After Five, But Within Ten Years, Amortized Cost	121,794
Available for sale securities and Held to maturity securities, After Five, But Within Ten Years, Fair Value	108,174
Available for sale securities and Held to maturity securities, After Ten Years, Amortized Cost	1,041,121
Available for sale securities and Held to maturity securities, After Ten Years, Fair Value	862,700
Available for sale securities and Held to maturity securities, Total, Amortized Cost	1,234,024
Available for sale securities and Held to maturity securities, Total, Fair Value	1,039,002
U.S. Government Sponsored Enterprise Obligations
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Available for sale securities, After One, But Within Five Years, Amortized Cost	9,997
Available for sale securities, After One, But Within Five Years, Fair Value	9,012
Available for sale securities, After Five, But Within Ten Years, Amortized Cost	5,000
Available for sale securities, After Five, But Within Ten Years, Fair Value	4,346
Available for sale securities, After Ten Years, Amortized Cost	8,000
Available for sale securities, After Ten Years, Fair Value	6,375
Available for sale securities, Total, Amortized Cost	22,997
Available for sale securities, Total, Fair Value	19,733
U.S. Treasury Notes
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Held to maturity securities, Within One Year, Amortized Cost	987
Held to maturity securities, Within One Year, Fair Value	983
Held to maturity securities, After One, But Within Five Years, Amortized Cost	2,983
Held to maturity securities, After One, But Within Five Years, Fair Value	2,969
Held to maturity securities, Amortized Cost	3,970
Held to maturity securities, Fair Value	3,952
Mortgage-Backed Securities
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Available for sale securities, After One, But Within Five Years, Amortized Cost	10,680
Available for sale securities, After One, But Within Five Years, Fair Value	9,966
Available for sale securities, After Five, But Within Ten Years, Amortized Cost	41,622
Available for sale securities, After Five, But Within Ten Years, Fair Value	34,934
Available for sale securities, After Ten Years, Amortized Cost	105,732
Available for sale securities, After Ten Years, Fair Value	87,783
Available for sale securities, Total, Amortized Cost	158,034
Available for sale securities, Total, Fair Value	132,683
Held to maturity securities, After One, But Within Five Years, Amortized Cost	19,572
Held to maturity securities, After One, But Within Five Years, Fair Value	18,355
Held to maturity securities, After Five, But Within Ten Years, Amortized Cost	48,731
Held to maturity securities, After Five, But Within Ten Years, Fair Value	42,866
Held to maturity securities, After Ten Years, Amortized Cost	883,069
Held to maturity securities, After Ten Years, Fair Value	732,947
Held to maturity securities, Amortized Cost	951,372
Held to maturity securities, Fair Value	794,168
Corporate Debt Securities
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Available for sale securities, Within One Year, Amortized Cost	996
Available for sale securities, Within One Year, Fair Value	1,000
Available for sale securities, Total, Amortized Cost	996
Available for sale securities, Total, Fair Value	1,000
Held to maturity securities, After One, But Within Five Years, Amortized Cost	250
Held to maturity securities, After One, But Within Five Years, Fair Value	244
Held to maturity securities, Amortized Cost	250
Held to maturity securities, Fair Value	244
Municipal Securities
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Held to maturity securities, Within One Year, Amortized Cost	6,987
Held to maturity securities, Within One Year, Fair Value	6,997
Held to maturity securities, After One, But Within Five Years, Amortized Cost	18,657
Held to maturity securities, After One, But Within Five Years, Fair Value	18,602
Held to maturity securities, After Five, But Within Ten Years, Amortized Cost	26,441
Held to maturity securities, After Five, But Within Ten Years, Fair Value	26,028
Held to maturity securities, After Ten Years, Amortized Cost	44,320
Held to maturity securities, After Ten Years, Fair Value	35,595
Held to maturity securities, Amortized Cost	96,405	105,081
Held to maturity securities, Fair Value	$ 87,222	$ 108,363

Investment Securities - Gross U

Investment Securities - Gross Unrealized Losses of Aggregated by Investment Category and Length of Time that Individual Investment Securities have been in Continuous Loss Position (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Available for sale securities, Fair Value, Less than 12 months	$ 52,554	$ 80,365
Available for sale securities, Unrealized Losses, Less than 12 months	(5,375)	(2,371)
Available for sale securities, Fair Value, 12 months or longer	99,557	52,755
Available for sale securities, Unrealized Losses, 12 months or longer	(23,243)	(2,325)
Available for sale securities, Fair Value	152,111	133,120
Available for sale securities, Unrealized Losses	(28,618)	(4,696)
Held to maturity securities, Fair Value, Less than 12 months	286,872	753,573
Held to maturity securities, Unrealized Losses, Less than 12 months	(26,774)	(12,703)
Held to maturity securities, Fair Value, 12 months or longer	576,549	21,061
Held to maturity securities, Unrealized Losses, 12 months or longer	(139,729)	(1,071)
Held to maturity securities, Fair Value	863,421	774,634
Held to maturity securities, Unrealized Losses	(166,503)	(13,774)
Fair Value, Less than 12 months	339,426	833,938
Unrealized Losses, Less than 12 months	(32,149)	(15,074)
Fair Value, 12 months or longer	676,106	73,816
Unrealized Losses, 12 months or longer	(162,972)	(3,396)
Fair Value	1,015,532	907,754
Unrealized Losses	(195,121)	(18,470)
U.S. Government Sponsored Enterprise Obligations
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Available for sale securities, Fair Value, Less than 12 months	10,722	4,881
Available for sale securities, Unrealized Losses, Less than 12 months	(2,278)	(115)
Available for sale securities, Fair Value, 12 months or longer	9,012	4,884
Available for sale securities, Unrealized Losses, 12 months or longer	(986)	(116)
Available for sale securities, Fair Value	19,734	9,765
Available for sale securities, Unrealized Losses	(3,264)	(231)
U.S. Treasury Notes
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Held to maturity securities, Fair Value, Less than 12 months	3,952
Held to maturity securities, Unrealized Losses, Less than 12 months	(18)
Held to maturity securities, Fair Value	3,952
Held to maturity securities, Unrealized Losses	(18)
Mortgage-Backed Securities
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Available for sale securities, Fair Value, Less than 12 months	41,832	74,724
Available for sale securities, Unrealized Losses, Less than 12 months	(3,097)	(2,253)
Available for sale securities, Fair Value, 12 months or longer	90,545	47,871
Available for sale securities, Unrealized Losses, 12 months or longer	(22,257)	(2,209)
Available for sale securities, Fair Value	132,377	122,595
Available for sale securities, Unrealized Losses	(25,354)	(4,462)
Held to maturity securities, Fair Value, Less than 12 months	230,708	740,966
Held to maturity securities, Unrealized Losses, Less than 12 months	(22,362)	(12,509)
Held to maturity securities, Fair Value, 12 months or longer	562,835	15,345
Held to maturity securities, Unrealized Losses, 12 months or longer	(134,846)	(749)
Held to maturity securities, Fair Value	793,543	756,311
Held to maturity securities, Unrealized Losses	(157,208)	(13,258)
Municipal Securities
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Held to maturity securities, Fair Value, Less than 12 months	51,969	12,607
Held to maturity securities, Unrealized Losses, Less than 12 months	(4,388)	(194)
Held to maturity securities, Fair Value, 12 months or longer	13,714	5,716
Held to maturity securities, Unrealized Losses, 12 months or longer	(4,883)	(322)
Held to maturity securities, Fair Value	65,683	18,323
Held to maturity securities, Unrealized Losses	(9,271)	(516)
Corporate Debt Securities
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Available for sale securities, Fair Value, Less than 12 months	243	760
Available for sale securities, Unrealized Losses, Less than 12 months	(6)	(3)
Available for sale securities, Fair Value	243	760
Available for sale securities, Unrealized Losses	$ (6)	$ (3)

Investment Securities - Additio

Investment Securities - Additional Information (Details)	Dec. 31, 2022 USD ($) Security	Dec. 31, 2021 USD ($) Security
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Number of debt securities with unrealized losses | Security	432
Aggregate depreciation percentage of gross unrealized losses from amortized cost	16.10%
Percentage of unrealized dollar loss on amortized cost	21.50%
Percentage of unrealized loss on amortized cost	35%
Unrealized dollar loss of amortized cost basis	$ 2,000,000
Unrealized loss of amortized cost basis	823,000
Number of investment securities pledged | Security		0
Security held as collateral, amortized cost	182,027,000	$ 201,270,000
Pledged as Collateral
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Security held as collateral, amortized cost	9,100,000
Security held as collateral, fair value	8,000,000
U.S. Government Sponsored Enterprise Obligations
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Security held as collateral, amortized cost	$ 22,997,000	$ 22,996,000

Investment Securities - Summa_2

Investment Securities - Summary of Gains (Losses) from Sale of Investment Securities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Amortized cost of securities sold	$ 19,018	$ 10,752
Gross gains realized on securities sold		111
Gross losses realized on securities sold		(42)
Net proceeds from securities sold	$ 19,018	$ 10,821

Investment Securities - Summa_3

Investment Securities - Summary of Credit Rating of Debt Securities Portfolio (Details) - USD ($) $ in Thousands		Dec. 31, 2022	Dec. 31, 2021
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Total available for sale securities		$ 153,416	$ 197,803
Total held to maturity securities		1,051,997	977,061
Municipal Securities
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Total held to maturity securities		96,405	105,081
Corporate Debt Securities
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Total available for sale securities		1,000	1,764
Total held to maturity securities		250	6,997
U.S. Government Sponsored Enterprise Obligations
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Total available for sale securities		19,733	23,011
U.S. Treasury Notes
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Total held to maturity securities		3,970
AAA/AA/A
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Total available for sale securities		152,416	196,798
Total held to maturity securities		1,051,997	977,061
AAA/AA/A | Municipal Securities
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Total held to maturity securities		96,405	105,081
AAA/AA/A | Corporate Debt Securities
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Total available for sale securities			759
Total held to maturity securities		250	6,997
AAA/AA/A | U.S. Government Sponsored Enterprise Obligations
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Total available for sale securities		19,733	23,011
AAA/AA/A | U.S. Treasury Notes
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Total held to maturity securities		3,970
BBB/BB/B
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Total available for sale securities		1,000	1,005
BBB/BB/B | Corporate Debt Securities
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Total available for sale securities		1,000	1,005
Mortgage Backed Securities
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Total available for sale securities	[1]	132,683	173,028
Total held to maturity securities	[1]	951,372	864,983
Mortgage Backed Securities | AAA/AA/A
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Total available for sale securities	[1]	132,683	173,028
Total held to maturity securities	[1]	$ 951,372	$ 864,983
[1] Includes Agency mortgage-backed pass-through securities and collateralized mortgage obligations issued by U.S. Government Sponsored enterprises ("GSEs") and U.S. government agencies, such as FNMA, FHLMC, and GNMA that are not rated by Moody’s or Standard & Poor's. Each security contains a guarantee by the issuing GSE or agency and therefore carries an implicit guarantee of the U.S. government. These have been categorized as AAA/AA/A.

Loans and Allowance for Credi_3

Loans and Allowance for Credit Losses - Loans Outstanding by Category (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Loans And Leases Receivable Disclosure [Line Items]
Total loans	$ 4,062,856	$ 3,319,106
Residential Mortgage
Loans And Leases Receivable Disclosure [Line Items]
Deferred costs (fees) net of unearned fees	6,613	5,936
Total loans	1,648,838	1,415,079
Residential Mortgage | Construction
Loans And Leases Receivable Disclosure [Line Items]
Loans outstanding by category gross	35,299	13,012
Residential Mortgage | Mortgages - Fixed Rate
Loans And Leases Receivable Disclosure [Line Items]
Loans outstanding by category gross	902,968	716,456
Residential Mortgage | Mortgages - Adjustable Rate
Loans And Leases Receivable Disclosure [Line Items]
Loans outstanding by category gross	703,958	679,675
Commercial Mortgage
Loans And Leases Receivable Disclosure [Line Items]
Deferred costs (fees) net of unearned fees	2,318	1,989
Total loans	1,914,423	1,511,002
Commercial Mortgage | Construction
Loans And Leases Receivable Disclosure [Line Items]
Loans outstanding by category gross	135,782	86,246
Commercial Mortgage | Mortgages - Non-owner Occupied
Loans And Leases Receivable Disclosure [Line Items]
Loans outstanding by category gross	1,592,732	1,272,135
Commercial Mortgage | Mortgages - Owner Occupied
Loans And Leases Receivable Disclosure [Line Items]
Loans outstanding by category gross	183,591	150,632
Home Equity
Loans And Leases Receivable Disclosure [Line Items]
Deferred costs (fees) net of unearned fees	292	304
Total loans	111,351	87,960
Home Equity | Home Equity - Lines of Credit
Loans And Leases Receivable Disclosure [Line Items]
Loans outstanding by category gross	108,961	85,639
Home Equity | Home Equity - Term Loans
Loans And Leases Receivable Disclosure [Line Items]
Loans outstanding by category gross	2,098	2,017
Commercial and Industrial
Loans And Leases Receivable Disclosure [Line Items]
Loans outstanding by category gross	349,026	247,024
Unearned fees, net of deferred costs	240	(434)
Total loans	350,650	269,446
Commercial and Industrial | PPP Loans
Loans And Leases Receivable Disclosure [Line Items]
Loans outstanding by category gross	1,384	22,856
Consumer
Loans And Leases Receivable Disclosure [Line Items]
Deferred costs (fees) net of unearned fees	18	8
Total loans	37,594	35,619
Consumer | Secured
Loans And Leases Receivable Disclosure [Line Items]
Loans outstanding by category gross	35,679	34,308
Consumer | Unsecured
Loans And Leases Receivable Disclosure [Line Items]
Loans outstanding by category gross	$ 1,897	$ 1,303

Loans and Allowance for Credi_4

Loans and Allowance for Credit Losses - Additional Information (Details)	12 Months Ended
	Dec. 31, 2022 USD ($) Loan	Dec. 31, 2021 USD ($) Loan
Financing Receivable Modifications [Line Items]
Commitments to lend additional funds to borrowers whose loans were on non-accrual status	$ 0	$ 0
Number of loans modified during the period | Loan	0	0
Number of loans determined to be troubled debt restructurings | Loan	4	4
Number of TDRs defaulted during the period | Loan	0	0
Allowance for credit losses	$ 39,870,000	$ 35,880,000
Loans in deferral	0
Loans 90 days or more past due and still accruing	0	0
Troubled Debt Restructurings
Financing Receivable Modifications [Line Items]
Troubled debt restructuring carrying value	704,000	758,000
Allowance for credit losses	$ 60,000	$ 85,000

Loans and Allowance for Credi_5

Loans and Allowance for Credit Losses - Non-performing Loans Disaggregated by Loan Category (Details) - Non-Performing Loans - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable Recorded Investment Past Due [Line Items]
Non-accrual loans	$ 5,839	$ 4,628
Troubled debt restructurings	703	758
Total	6,542	5,386
Residential Mortgage
Financing Receivable Recorded Investment Past Due [Line Items]
Non-accrual loans	4,733	3,777
Troubled debt restructurings	622	652
Total	5,355	4,429
Commercial Mortgage
Financing Receivable Recorded Investment Past Due [Line Items]
Non-accrual loans	311	517
Total	311	517
Home Equity
Financing Receivable Recorded Investment Past Due [Line Items]
Non-accrual loans	722	223
Total	722	223
Commercial & Industrial
Financing Receivable Recorded Investment Past Due [Line Items]
Non-accrual loans	73	111
Troubled debt restructurings	81	106
Total	$ 154	$ 217

Loans and Allowance for Credi_6

Loans and Allowance for Credit Losses - Loans Receivable Disaggregated by Credit Quality Indicator (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Residential Mortgage
Financing Receivable Recorded Investment [Line Items]
2022	$ 314,599
2021	511,217	$ 535,071
2020	276,904	329,652
2019	113,566	135,139
2018	78,304	101,438
2017		77,756
Prior	354,248	236,023
Total	1,648,838	1,415,079
Residential Mortgage | Current
Financing Receivable Recorded Investment [Line Items]
2022	314,599
2021	511,217	535,071
2020	276,698	329,501
2019	113,251	135,139
2018	77,620	101,108
2017		77,702
Prior	350,098	232,129
Total	1,643,483	1,410,650
Residential Mortgage | Non-Performing Loans
Financing Receivable Recorded Investment [Line Items]
2020	206	151
2019	315
2018	684	330
2017		54
Prior	4,150	3,894
Total	5,355	4,429
Home Equity
Financing Receivable Recorded Investment [Line Items]
2022	3,611
2020		719
2019	58	3,311
2018	360	4,469
2017		5,060
Prior	481	5,475
Revolving loans amortized cost basis	106,841	68,926
Total	111,351	87,960
Home Equity | Current
Financing Receivable Recorded Investment [Line Items]
2022	3,611
2021		719
2020		3,088
2019	58	4,469
2018	360	5,060
Prior	481	5,475
Revolving loans amortized cost basis	106,119	68,926
Total	110,629	87,737
Home Equity | Non-Performing Loans
Financing Receivable Recorded Investment [Line Items]
2019		223
Revolving loans amortized cost basis	722
Total	722	223
Consumer
Financing Receivable Recorded Investment [Line Items]
2022	13,214
2021	8,482	14,427
2020	5,353	8,758
2019	444	1,544
2018	2,078	3,168
2017		1,838
Prior	7,424	5,357
Revolving loans amortized cost basis	599	527
Total	37,594	35,619
Consumer | Current
Financing Receivable Recorded Investment [Line Items]
2022	13,214
2021	8,482	14,427
2020	5,353	8,758
2019	444	1,544
2018	2,078	3,168
2017		1,838
Prior	7,424	5,357
Revolving loans amortized cost basis	599	527
Total	37,594	35,619
Commercial Mortgage
Financing Receivable Recorded Investment [Line Items]
2022	411,927
2021	330,593	319,633
2020	226,635	249,787
2019	302,166	361,068
2018	147,095	180,933
2017		95,929
Prior	496,007
Prior		303,652
Total	1,914,423	1,511,002
Commercial Mortgage | 1-6 (Pass)
Financing Receivable Recorded Investment [Line Items]
2022	411,927
2021	330,593	319,633
2020	222,073	248,691
2019	260,588	320,189
2018	125,398	158,462
2017		93,016
Prior	489,564
Prior		298,791
Total	1,840,143	1,438,782
Commercial Mortgage | 7 (Special Mention)
Financing Receivable Recorded Investment [Line Items]
2020	4,562	1,096
2019	41,578	40,879
2018	21,697	22,471
2017		2,913
Prior	6,132
Prior		4,131
Total	73,969	71,490
Commercial Mortgage | 8 (Substandard)
Financing Receivable Recorded Investment [Line Items]
Prior	311
Prior		730
Total	311	730
Commercial and Industrial
Financing Receivable Recorded Investment [Line Items]
2022	128,301
2021	71,938	83,932
2020	62,783	78,215
2019	30,820	46,153
2018	19,282	35,270
2017		19,888
Prior	37,041
Prior		5,625
Revolving loans amortized cost basis	485	363
Total	350,650	269,446
Commercial and Industrial | 1-6 (Pass)
Financing Receivable Recorded Investment [Line Items]
2022	128,301
2021	67,727	83,614
2020	62,025	77,073
2019	28,557	38,299
2018	18,794	34,360
2017		19,727
Prior	36,836
Prior		4,622
Revolving loans amortized cost basis	475	353
Total	342,715	258,048
Commercial and Industrial | 7 (Special Mention)
Financing Receivable Recorded Investment [Line Items]
2021	4,211	318
2020	130	350
2019	161	5,523
2018	407	406
2017		161
Prior	121
Prior		859
Revolving loans amortized cost basis	10	10
Total	5,040	7,627
Commercial and Industrial | 8 (Substandard)
Financing Receivable Recorded Investment [Line Items]
2020	628	792
2019	2,102	2,331
2018	81	504
Prior	84
Prior		144
Total	$ 2,895	$ 3,771

Loans and Allowance for Credi_7

Loans and Allowance for Credit Losses - Schedule of Loans Receivable Disaggregated by Past Due Status (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	$ 4,046,250	$ 3,306,858
Total loans	4,062,856	3,319,106
30-59 Days Past Due
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	12,467	9,265
60-89 Days Past Due
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	2,116	1,495
90 Days or Greater
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	2,023	1,488
Total Past Due
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	16,606	12,248
Residential Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	1,634,216	1,404,706
Total loans	1,648,838	1,415,079
Residential Mortgage | 30-59 Days Past Due
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	11,359	8,470
Residential Mortgage | 60-89 Days Past Due
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	1,454	415
Residential Mortgage | 90 Days or Greater
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	1,809	1,488
Residential Mortgage | Total Past Due
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	14,622	10,373
Commercial Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	1,914,423	1,510,526
Total loans	1,914,423	1,511,002
Commercial Mortgage | 30-59 Days Past Due
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due		476
Commercial Mortgage | Total Past Due
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due		476
Home Equity
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	109,782	87,003
Total loans	111,351	87,960
Home Equity | 30-59 Days Past Due
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	962	314
Home Equity | 60-89 Days Past Due
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	393	643
Home Equity | 90 Days or Greater
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	214
Home Equity | Total Past Due
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	1,569	957
Commercial and Industrial
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	350,316	269,004
Total loans	350,650	269,446
Commercial and Industrial | 30-59 Days Past Due
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	65	5
Commercial and Industrial | 60-89 Days Past Due
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	269	437
Commercial and Industrial | Total Past Due
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	334	442
Consumer
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	37,513	35,619
Total loans	37,594	$ 35,619
Consumer | 30-59 Days Past Due
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	81
Consumer | Total Past Due
Financing Receivable Allowance For Credit Losses [Line Items]
Total Principal Balance/Past Due	$ 81

Loans and Allowance for Credi_8

Loans and Allowance for Credit Losses - Summary of Changes in Allowance for Credit Losses Disaggregated by Loan Category (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses-loan portfolio, Beginning Balance	$ 35,880
Provision for (release of) credit losses - unfunded commitments	3,881	$ (1,294)	$ 18,310
Allowance for credit losses-loan portfolio, Ending Balance	39,870	35,880
Funded Commitments
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses-loan portfolio, Beginning Balance	34,496	36,016
Provision for acquired loans	2,102
Initial allowance for PCD	56
Charge-offs	(52)	(87)
Recoveries	105	241
Provision for (release of) credit losses - loan portfolio	1,067	(1,674)
Allowance for credit losses-loan portfolio, Ending Balance	37,774	34,496	36,016
Unfunded Commitments
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses-loan portfolio, Beginning Balance	1,384	1,004
Acquired loan commitments	137
Provision for (release of) credit losses - unfunded commitments	575	380
Allowance for credit losses-unfunded commitments	2,096	1,384
Allowance for credit losses-loan portfolio, Ending Balance		1,384	1,004
Residential Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses-loan portfolio, Beginning Balance	13,383
Allowance for credit losses-loan portfolio, Ending Balance	13,321	13,383
Residential Mortgage | Funded Commitments
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses-loan portfolio, Beginning Balance	13,383	13,067
Provision for acquired loans	527
Initial allowance for PCD	19
Charge-offs		(4)
Recoveries	4
Provision for (release of) credit losses - loan portfolio	(612)	320
Allowance for credit losses-loan portfolio, Ending Balance	13,321	13,383	13,067
Commercial Mortgage
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses-loan portfolio, Beginning Balance	17,133
Allowance for credit losses-loan portfolio, Ending Balance	19,086	17,133
Commercial Mortgage | Funded Commitments
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses-loan portfolio, Beginning Balance	17,133	18,564
Provision for acquired loans	1,337
Initial allowance for PCD	37
Recoveries		30
Provision for (release of) credit losses - loan portfolio	579	(1,461)
Allowance for credit losses-loan portfolio, Ending Balance	19,086	17,133	18,564
Home Equity
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses-loan portfolio, Beginning Balance	406
Allowance for credit losses-loan portfolio, Ending Balance	573	406
Home Equity | Funded Commitments
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses-loan portfolio, Beginning Balance	406	552
Provision for acquired loans	117
Provision for (release of) credit losses - loan portfolio	50	(146)
Allowance for credit losses-loan portfolio, Ending Balance	573	406	552
Commercial & Industrial
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses-loan portfolio, Beginning Balance	2,989
Allowance for credit losses-loan portfolio, Ending Balance	4,153	2,989
Commercial & Industrial | Funded Commitments
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses-loan portfolio, Beginning Balance	2,989	3,309
Provision for acquired loans	113
Charge-offs	(23)	(41)
Recoveries	89	181
Provision for (release of) credit losses - loan portfolio	985	(460)
Allowance for credit losses-loan portfolio, Ending Balance	4,153	2,989	3,309
Consumer
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses-loan portfolio, Beginning Balance	585
Allowance for credit losses-loan portfolio, Ending Balance	641	585
Consumer | Funded Commitments
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses-loan portfolio, Beginning Balance	585	524
Provision for acquired loans	8
Charge-offs	(29)	(42)
Recoveries	12	30
Provision for (release of) credit losses - loan portfolio	65	73
Allowance for credit losses-loan portfolio, Ending Balance	641	585	524
Unfunded Commitments
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses-loan portfolio, Beginning Balance	1,384
Allowance for credit losses-loan portfolio, Ending Balance	2,096	1,384
Unfunded Commitments | Unfunded Commitments
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses-loan portfolio, Beginning Balance	1,384	1,004
Acquired loan commitments	137
Provision for (release of) credit losses - unfunded commitments	575	380
Allowance for credit losses-unfunded commitments	$ 2,096	1,384
Allowance for credit losses-loan portfolio, Ending Balance		$ 1,384	$ 1,004

Federal Home Loan Bank ("FHLB_2

Federal Home Loan Bank ("FHLB") of Boston Stock - Additional Information (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021
Federal Home Loan Bank ("FHLB") Stock [Line Items]
Federal Home Loan Bank ("FHLB") of Boston Stock, at cost	$ 6,264,000	$ 4,816,000
Federal Home Loan Bank ("FHLB") of Boston
Federal Home Loan Bank ("FHLB") Stock [Line Items]
Federal Home Loan Bank ("FHLB") of Boston Stock, at cost	6,300,000	4,800,000
Impairment on investment of federal home loan bank ("FHLB") stock	$ 0	$ 0

Banking Premises and Equipmen_2

Banking Premises and Equipment - Summary of Cost and Accumulated Depreciation and Amortization of Property, Leasehold Improvements and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Property Plant And Equipment [Line Items]
Banking premises and equipment, Subtotal	$ 49,171	$ 40,381
Accumulated depreciation and amortization	(25,874)	(23,055)
Total	23,297	17,326
Land
Property Plant And Equipment [Line Items]
Banking premises and equipment, Subtotal	3,396	1,516
Building and leasehold improvements
Property Plant And Equipment [Line Items]
Banking premises and equipment, Subtotal	$ 25,588	20,254
Building and leasehold improvements | Minimum
Property Plant And Equipment [Line Items]
Estimated Useful Lives	3 years
Building and leasehold improvements | Maximum
Property Plant And Equipment [Line Items]
Estimated Useful Lives	30 years
Equipment, including vaults
Property Plant And Equipment [Line Items]
Banking premises and equipment, Subtotal	$ 20,165	18,592
Equipment, including vaults | Minimum
Property Plant And Equipment [Line Items]
Estimated Useful Lives	3 years
Equipment, including vaults | Maximum
Property Plant And Equipment [Line Items]
Estimated Useful Lives	20 years
Work in process
Property Plant And Equipment [Line Items]
Banking premises and equipment, Subtotal	$ 22	$ 19

Banking Premises and Equipmen_3

Banking Premises and Equipment - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 2.7	$ 2.6	$ 2.5

Intangible Assets - Additional

Intangible Assets - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Finite Lived Intangible Assets [Line Items]
Carrying value of intangible asset	$ 7,443,000	$ 2,617,000
Mortgage Servicing Rights
Finite Lived Intangible Assets [Line Items]
Weighted average amortization period	7 years 1 month 6 days	5 years 8 months 12 days
Amount of mortgage loans sold and servicing rights retained	$ 5,800,000	$ 25,300,000	$ 60,500,000
Fair value of mortgage servicing rights portfolio	2,300,000	1,500,000
North Mark Merger | Core Deposit Intangibles
Finite Lived Intangible Assets [Line Items]
Intangible assets acquired	5,300,000
Amortization of intangible asset	494,000	361,000	$ 361,000
Carrying value of intangible asset	$ 7,400,000	$ 2,600,000
Weighted average amortization period	8 years 8 months 12 days	7 years 3 months 18 days

Intangible Assets - Schedule of

Intangible Assets - Schedule of Mortgage Servicing Rights (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Beginning Balance, Mortgage servicing rights	$ 1,083	$ 1,361	$ 1,347
Mortgage servicing rights capitalized, Mortgage servicing rights	71	281	536
Amortization charged against servicing income, Mortgage servicing rights	(274)	(559)	(572)
Ending Balance, Mortgage servicing rights	1,665	1,083	1,361
Beginning Balance, Valuation allowance		(142)	(26)
Change in impairment reserve, Valuation allowance		142	(116)
Ending Balance, Valudation allowance			(142)
Beginning Balance, Total	1,083	1,219	1,321
Mortgage servicing rights capitalized, Total	71	281	536
Amortization charged against servicing income, Total	(274)	(559)	(572)
Change in impairment reserve, Total		142	(116)
Ending Balance, Total	1,665	$ 1,083	1,219
North Mark Merger
Finite-Lived Intangible Assets [Line Items]
Mortgage servicing rights acquired as a result of the merger, Mortgage servicing rights	785
Mortgage servicing rights acquired as a result of the merger, Total	$ 785
Wellesley Merger
Finite-Lived Intangible Assets [Line Items]
Mortgage servicing rights acquired as a result of the merger, Mortgage servicing rights			50
Mortgage servicing rights acquired as a result of the merger, Total			$ 50

Intangible Assets - Schedule _2

Intangible Assets - Schedule of Aggregate Estimated Future Amortization Expense (Details) - Mortgage Servicing Rights $ in Thousands	Dec. 31, 2022 USD ($)
Future Amortization Expense
2023	$ 217
2024	150
2025	170
2026	192
2027	132
Thereafter	804
Total	$ 1,665

Deposits - Summary of Deposits

Deposits - Summary of Deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deposits [Abstract]
Demand deposits (non-interest bearing)	$ 1,366,395	$ 1,393,935
Interest bearing checking	908,961	763,188
Money market	1,162,773	1,104,238
Savings	790,628	907,722
Retail certificates of deposit under $250,000	117,532	99,196
Retail certificates of deposit $250,000 or greater	87,528	60,171
Brokered certificates of deposit	381,559	2,702
Total deposits	$ 4,815,376	$ 4,331,152

Deposits - Schedule of Maturiti

Deposits - Schedule of Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deposits [Abstract]
2022		$ 132,212
2023	$ 533,513	19,062
2024	39,753	4,443
2025	5,377	2,182
2026	6,021	4,170
2027 and after	1,955
Total certificates of deposit	$ 586,619	$ 162,069

Deposits - Additional Informati

Deposits - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Deposits [Abstract]
Deposit accounts of directors, executive officers and their respective affiliates	$ 2.7	$ 7.5

Borrowings - Additional Informa

Borrowings - Additional Information (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Short-term advances outstanding from FHLB of boston		$ 100,000,000	$ 0
Weighted average interest rate		4.38%
Repurchase agreement		$ 5,000,000	0
Average balance of securities sold under agreements to repurchase		1,200,000
Borrowings under PPP loan	$ 85,400,000	0	0
Percentage of debt instrument interest rate stated	0.35%
Unused borrowing capacity based upon collateral pledged		$ 639,000,000
Minimum
Debt Instrument [Line Items]
Percentage of carrying value, secured blanket lien on qualified collateral		60%
Maximum
Debt Instrument [Line Items]
Percentage of carrying value, secured blanket lien on qualified collateral		70%
Investment Securities Commercial Real Estate and Commercial and Industrial Loans | Line of Credit
Debt Instrument [Line Items]
Collateral pledged amount		$ 970,100,000	652,300,000
FRB Boston | Investment Securities Commercial Real Estate and Commercial and Industrial Loans
Debt Instrument [Line Items]
Line of credit unused borrowing capacity		$ 680,400,000	$ 419,600,000
Subordinated Debt
Debt Instrument [Line Items]
Redemption amount	$ 10,000,000
Coupon rate	6%

Borrowings - Schedule of Inform

Borrowings - Schedule of Information Relating to Long-term Borrowings from FHLB of Boston (Details) - USD ($) $ in Thousands		Dec. 31, 2022	Dec. 31, 2021
Federal Home Loan Bank Advances [Line Items]
FHLB of Boston long-term borrowings		$ 176	$ 16,442
FHLB of Boston long-term borrowings, percentage		2.36%	3.67%
2022
Federal Home Loan Bank Advances [Line Items]
FHLB of Boston long-term borrowings			$ 221
FHLB of Boston long-term borrowings, percentage			1.84%
2023
Federal Home Loan Bank Advances [Line Items]
FHLB of Boston long-term borrowings	[1]	$ 176	$ 16,221
FHLB of Boston long-term borrowings, percentage	[1]	2.36%	3.69%
[1] December 31, 2021 totals includes a $ 15 million advance with an interest rate of 3.80 %, that was callable by the FHLB of Boston on January 27, 2022 .

Borrowings - Schedule of Info_2

Borrowings - Schedule of Information Relating to Long-term Borrowings from FHLB of Boston (Parenthetical) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Federal Home Loan Bank, Advances [Line Items]
FHLB of Boston long-term borrowings	$ 176	$ 16,442
FHLB of Boston long-term borrowings, percentage	2.36%	3.67%
FHLB Boston [Member]
Federal Home Loan Bank, Advances [Line Items]
FHLB of Boston long-term borrowings		$ 15,000
FHLB of Boston long-term borrowings, percentage		3.80%
FHLB of Boston long-term borrowings, callable date	Jan. 27, 2022

Income Taxes - Components of In

Income Taxes - Components of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Current tax expense
Federal	$ 12,906	$ 11,330	$ 7,877
State	5,559	4,862	4,192
Total current tax expense	18,465	16,192	12,069
Deferred tax expense (benefit)
Federal	455	(1,840)	(250)
State	132	1,059	(415)
Total deferred tax expense (benefit)	587	2,899	(665)
Total income tax expense	$ 19,052	$ 19,091	$ 11,404

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Total Income Tax Expense, Calculated at Statutory Federal Income Tax Rates, to Income Tax Expense in Consolidated Statements of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income tax expense at statutory rate of 21.0%	$ 15,112	$ 15,354	$ 9,106
Increase/(decrease) resulting from:
State tax, net of federal tax benefit	4,496	4,678	2,984
Tax-exempt income	(814)	(795)	(694)
ESOP dividends	(150)	(145)	(125)
Bank owned life insurance	(133)	(165)	(157)
Compensation limited under 162(m)	193	226	511
Benefit from stock compensation	(81)	(46)
Non-deductible acquisition costs	182		186
Non-deductible expenses	44	55
Impact of CARES Act			(539)
BOLI surrender, death benefit	310
Other	(107)	(71)	132
Total income tax expense	$ 19,052	$ 19,091	$ 11,404
Income tax expense at statutory rates	21%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Taxes [Line Items]
Current federal tax rates	21%
Net operating losses carryback period	5 years
Income tax benefit	$ (19,052,000)	$ (19,091,000)	$ (11,404,000)
Tax rate deferred tax assets were measured	27.95%	27.92%
Deferred tax assets, valuation allowance	$ 0	$ 0
Unrecognized tax benefits	$ 0	$ 0
Federal Income Tax | Earliest Tax Year
Income Taxes [Line Items]
Income tax returns year open and subject to examination	2019
Federal Income Tax | Latest Tax Year
Income Taxes [Line Items]
Income tax returns year open and subject to examination	2022
State Income Tax | Earliest Tax Year
Income Taxes [Line Items]
Income tax returns year open and subject to examination	2019
State Income Tax | Latest Tax Year
Income Taxes [Line Items]
Income tax returns year open and subject to examination	2022
State NOL [Member]
Income Taxes [Line Items]
Income tax benefit			$ 539,000

Income Taxes - Summary of Net D

Income Taxes - Summary of Net Deferred Tax Asset (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Gross deferred tax assets
Allowance for credit losses	$ 11,142	$ 10,019
Unrealized losses on available for sale securities	7,390	982
Incentive compensation	1,819	1,905
Equity based compensation	1,298	1,347
Lease liabilities	7,661	9,458
ESOP dividends	200	193
Intangibles and fair value marks (merger related)	2,322	658
Other	931	265
Total gross deferred tax assets	32,763	24,827
Gross deferred tax liabilities
Deferred loan origination costs	(2,886)	(2,324)
Retirement benefits	(1,745)	(535)
Depreciation of premises and equipment	(2,551)	(1,997)
Right of use asset	(7,014)	(8,733)
Mortgage servicing rights	(465)	(303)
Goodwill	(115)	(115)
Derivative transactions	(3)	(835)
Total gross deferred tax liabilities	(14,773)	(14,842)
Net deferred tax asset	$ 17,990	$ 9,985

Pension and Retirement Plans -

Pension and Retirement Plans - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer matching contribution, percent						10%
Transfers between fair value levels	$ 0	$ 0
Benefit obligation	$ 424,000	729,000
Minimum | Domestic Large Cap Equities
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentages	30%
Minimum | Domestic Small/Mid Cap Equities
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentages	5%
Minimum | International and emerging Equities
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentages	0%
Minimum | Cash and Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentages	20%
Maximum | Domestic Large Cap Equities
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentages	60%
Maximum | Domestic Small/Mid Cap Equities
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentages	20%
Maximum | International and emerging Equities
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentages	20%
Maximum | Cash and Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation percentages	60%
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, description	The Company has a noncontributory, defined benefit pension plan (“Pension Plan”) covering substantially all employees hired before May 2, 2011. The Company also provides supplemental retirement benefits to certain current and former executive officers of the Company under the terms of Supplemental Executive Retirement Agreements (“Supplemental Retirement Plan”).
Benefit obligation	$ 35,598,000	47,875,000	$ 50,117,000
Postretirement Medical Coverage
Defined Benefit Plan Disclosure [Line Items]
Employee eligibility age under the plan					65 years
Profit Sharing Plan
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, maximum employee contribution, percent				100%
Defined contribution plan, employer matching contribution, percent				4%
Profit Sharing Plan | 401(k)
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, maximum employee contribution, percent				100%
Profit Sharing Plan | Maximum | 401(k)
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer matching contribution, percent				4%
Employee Stock Ownership Plan (ESOP)
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, minimum number of hours of service per year required for eligibility	1000 hours
Defined contribution plan, minimum service period required for eligibility	12 months
Employee Stock Ownership Plan (ESOP) | Minimum
Defined Benefit Plan Disclosure [Line Items]
Employee eligibility age under the plan	21 years
Profit Sharing and ESOP Plans
Defined Benefit Plan Disclosure [Line Items]
Contribution expense related to plans	$ 4,500,000	4,000,000	3,600,000
Defined Contribution SERP Plan (“DC SERP”)
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer matching contribution, percent	10%
Contribution expense related to plans	$ 271,000	$ 201,000	$ 209,000

Pension and Retirement Plans _2

Pension and Retirement Plans - Schedule of Projected Benefit Obligations and Funded Status (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Change in projected benefit obligation
Obligation at beginning of year	$ 729,000
Obligation at end of year	424,000	$ 729,000
Pension Plan
Change in projected benefit obligation
Obligation at beginning of year	47,875,000	50,117,000
Interest cost	1,309,000	1,211,000
Actuarial (gain) loss	11,754,000	(1,838,000)
Benefits paid	(1,832,000)	(1,615,000)
Obligation at end of year	35,598,000	47,875,000
Change in plan assets
Fair value at beginning of year	60,638,000	55,802,000
Actual return on plan assets	8,457,000	6,451,000
Benefits paid	(1,832,000)	(1,615,000)
Fair value at end of year	50,349,000	60,638,000
Funded (underfunded) status at end of year	14,751,000	12,763,000
Supplemental Retirement Plan
Change in projected benefit obligation
Obligation at beginning of year	10,075,000	10,505,000
Service cost	399,000	400,000
Interest cost	260,000	223,000
Actuarial (gain) loss	(2,057,000)	(451,000)
Benefits paid	(617,000)	(602,000)
Obligation at end of year	8,060,000	10,075,000
Change in plan assets
Employer contribution	617,000	602,000
Benefits paid	(617,000)	(602,000)
Funded (underfunded) status at end of year	$ (8,060,000)	$ (10,075,000)

Pension and Retirement Plans _3

Pension and Retirement Plans - Schedule of Accumulated Benefit Obligation (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 35,598	$ 47,875
Supplemental Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 7,627	$ 9,472

Pension and Retirement Plans _4

Pension and Retirement Plans - Schedule of Amounts Recognized in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss	$ 373	$ (206)
Total	373	(206)
Supplemental Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss	(617)	1,468
Total	$ (617)	$ 1,468

Pension and Retirement Plans _5

Pension and Retirement Plans - Components of Net Periodic Benefit Cost and Amounts Recognized in Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Amounts recognized in other comprehensive income (loss)
Total recognized in other comprehensive income (loss)	$ (1,818)	$ (5,273)	$ 1,695
Pension Plan
Net periodic benefit cost
Interest cost	1,309	1,211
Expected return on assets	(3,876)	(3,566)
Amortization of prior service credit		(3)
Net periodic expense (benefit)	(2,567)	(2,358)
Amounts recognized in other comprehensive income (loss)
Net actuarial loss/(gain)	579	(4,723)
Amortization of prior service credit		3
Total recognized in other comprehensive income (loss)	579	(4,720)
Total recognized in net periodic expense (benefit) and other comprehensive income (loss)	(1,988)	(7,078)
Supplemental Retirement Plan
Net periodic benefit cost
Service cost	399	400
Interest cost	$ 260	$ 223
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Comprehensive Income (Loss), Net of Tax	Other Comprehensive Income (Loss), Net of Tax
Amortization of net actuarial loss	$ 28	$ 40
Net periodic expense (benefit)	687	663
Amounts recognized in other comprehensive income (loss)
Net actuarial loss/(gain)	(2,057)	(451)
Amortization of net actuarial loss	(28)	(40)
Total recognized in other comprehensive income (loss)	(2,085)	(491)
Total recognized in net periodic expense (benefit) and other comprehensive income (loss)	$ (1,398)	$ 172

Pension and Retirement Plans _6

Pension and Retirement Plans - Schedule of Weighted-average Assumptions Used to Determine Projected Benefit Obligations and Net Periodic Benefit Cost (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.22%	2.79%
Discount rate	2.79%	2.45%
Expected long-term return on plan assets	6.50%	6.50%
Supplemental Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.15%	2.63%
Rate of compensation increase	4%	4%
Discount rate	2.63%	2.21%
Rate of compensation increase	4%	4%

Pension and Retirement Plans _7

Pension and Retirement Plans - Schedule of Pension Plan Weighted-average Asset Allocations by Asset (Details)	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocations percentage	100%	100%
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocations percentage	60%	68%
Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocations percentage	33%	29%
Cash and Equivalents
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocations percentage	7%	3%

Pension and Retirement Plans _8

Pension and Retirement Plans - Summary of Various Categories of Pension Plan Assets (Details) - Pension Plan - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	$ 50,349	$ 60,638	$ 55,802
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	38,002	47,300
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	12,347	13,338
Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	3,676	1,689
Cash and Cash Equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	3,676	1,689
Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	12,347	13,338
Fixed Income | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	12,347	13,338
Common Stock, Large Cap Core
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets		16,940
Common Stock, Large Cap Core | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets		16,940
Common Stock, Small Cap Core
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets		2,359
Common Stock, Small Cap Core | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets		2,359
Mutual Funds, Domestic Equity
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	24,201	10,413
Mutual Funds, Domestic Equity | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	24,201	10,413
Mutual Funds, International
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	3,942	6,579
Mutual Funds, International | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	3,942	6,579
Mutual Funds, Domestic Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	6,183	9,320
Mutual Funds, Domestic Fixed Income | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	$ 6,183	$ 9,320

Pension and Retirement Plans _9

Pension and Retirement Plans - Schedule of Benefits Expected to be Paid in the Next Ten Years (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Year-ended December 31,
2023	$ 2,759
2024	2,826
2025	2,895
2026	3,014
2027	2,992
2028-2032	16,734
Total	31,220
Pension Plan
Year-ended December 31,
2023	2,124
2024	2,197
2025	2,270
2026	2,394
2027	2,378
2028-2032	12,695
Total	24,058
Supplemental Retirement Plan
Year-ended December 31,
2023	611
2024	606
2025	602
2026	597
2027	592
2028-2032	3,916
Total	6,924
Postretirement Healthcare Plan
Year-ended December 31,
2023	24
2024	23
2025	23
2026	23
2027	22
2028-2032	123
Total	$ 238

Share-Based Compensation - Addi

Share-Based Compensation - Additional Information (Details) - shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
DSP Plan and 2017 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total shares issued under this plan	7,386	5,941
Restricted Stock | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options time-vest period	3 years
Restricted Stock | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options time-vest period	5 years
Performance-Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options time-vest period	3 years
Time Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options time-vest period	3 years

Share-Based Compensation - Summ

Share-Based Compensation - Summary of Non-vested Restricted Shares Outstanding (Details) - Restricted Stock - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Non-vested at beginning of year	34,622	31,649
Number of Shares, Granted	14,380	18,781
Number of Shares, Vested	(11,450)	(11,691)
Number of Shares, Forfeited	(2,980)	(4,117)
Number of Shares, Non-vested at end of year	34,572	34,622
Weighted Average Grant Value, Non-vested at beginning of year	$ 78.20	$ 73.07
Weighted Average Grant Value, Granted	87.10	82.06
Weighted Average Grant Value, Vested	76.50	71.27
Weighted Average Grant Value, Forfeited	81.43	75.97
Weighted Average Grant Value, Non-vested at end of year	$ 82.19	$ 78.20

Share-Based Compensation - Su_2

Share-Based Compensation - Summary of Non-vested Performance-Based Restricted Stock Units Outstanding (Details) - Performance-Based Restricted Stock Units - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Units, Non-vested at beginning of year	74,699	75,246
Number of Units, Granted	37,263	32,697
Number of Units, Vested (Performance achieved)	(34,248)	(30,059)
Number of Units, Forfeited	(5,580)	(3,185)
Number of Units, Non-vested at end of year	72,134	74,699
Weighted Average Grant Value, Non-vested at beginning of year	$ 73.59	$ 73.41
Weighted Average Grant Value, Granted	88.18	77
Weighted Average Grant Value, Vested (Performance achieved)	70.36	76.56
Weighted Average Grant Value, Forfeited	79.92	75.06
Weighted Average Grant Value, Non-vested at end of year	$ 80.83	$ 73.59

Share-Based Compensation - Su_3

Share-Based Compensation - Summary of Non-vested Time-Based Restricted Stock Units Outstanding (Details) - Time Based Restricted Stock Units - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Non-vested at beginning of year	13,836	14,968
Number of Shares, Granted	8,796	7,464
Number of Shares, Vested	(7,417)	(7,899)
Number of Shares, Forfeited	(1,664)	(697)
Number of Shares, Non-vested at end of year	13,551	13,836
Weighted Average Grant Value, Non-vested at beginning of year	$ 75.91	$ 74.84
Weighted Average Grant Value, Granted	88.18	77
Weighted Average Grant Value, Vested	75.94	74.95
Weighted Average Grant Value, Forfeited	84.40	75.64
Weighted Average Grant Value, Non-vested at end of year	$ 82.81	$ 75.91

Share-Based Compensation - Sche

Share-Based Compensation - Schedule of Amounts Recognized in Consolidated Statement of Income for Restricted Stock, Time Based Restricted Stock Units and Performance Based Restricted Stock Units (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-Based Payment Arrangement, Noncash Expense [Abstract]
Share-based compensation expense	$ 2,875	$ 3,476	$ 4,923
Related income tax benefit	$ 804	$ 970	$ 1,375

Financial Instruments with Of_3

Financial Instruments with Off-Balance-Sheet Risk - Summary of Off-Balance-Sheet Financial Instruments with Contractual Amounts Include Present Credit Risk (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Standby Letters of Credit
Financial instruments whose contractual amount represents credit risk:
Financial instruments with off-balance-sheet risk	$ 24,234	$ 18,880
Unused Portion of Existing Lines of Credit
Financial instruments whose contractual amount represents credit risk:
Financial instruments with off-balance-sheet risk	1,073,567	809,383
Origination of New Loans
Financial instruments whose contractual amount represents credit risk:
Financial instruments with off-balance-sheet risk	25,411	70,633
Commitments to Sell Residential Mortgage Loans
Financial instruments whose notional amount exceeds the amount of credit risk:
Financial instrument notional amount exceeds credit risk	$ 250	$ 3,920

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Commitments and Contingencies [Line Items]
Description of operating lease expiration terms	operating leases and their terms expire between 2022 and 2032 and, in some instances, contain options to renew for periods up to
Renewal option period for operating leases	25 years
Existence of option to expire	true
Total rental expense	$ 7.6	$ 7.3	$ 7

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Components of Operating Lease Cost and Other Related Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 6,965	$ 6,976	$ 6,691
Variable lease cost (cost excluded from lease payments)	38	13	2
Sublease income	(316)	(65)	(65)
Total operating lease cost	6,687	6,924	6,628
Other Information
Cash paid for amounts included in the measurement of lease liabilities – operating cash flows for operating leases	7,263	7,259	6,547
Operating Lease -operating cash flows (liability reduction)	$ 6,401	$ 6,252	$ 5,430
Weighted average lease term - operating leases	5 years 5 months 12 days	6 years 1 month 17 days	6 years 10 months 24 days
Weighted average discount rate - operating leases	3.01%	2.94%	2.98%

Commitments and Contingencies_3

Commitments and Contingencies - Schedule of Total Minimum Lease Payments Due in Future Periods under Lease Agreements (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Lessee, Operating Lease, Liability, to be Paid [Abstract]
Year 1	$ 7,085
Year 2	6,085
Year 3	5,118
Year 4	3,882
Year 5	2,079
Thereafter	5,883
Total minimum lease payments	30,132
Less: interest	(2,719)
Total lease liability	$ 27,413	$ 33,871

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Details)	Dec. 31, 2022	Dec. 31, 2021	Jan. 01, 2015
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 risk based capital to risk weighted assets	0.125	0.124
Capital to risk weighted assets	0.135	0.136
Tier 1 capital to average assets of leverage ratio	0.085	0.083
Minimum
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Common equity tier 1 risk based capital to risk weighted assets	0.07		0.045
Tier 1 risk based capital to risk weighted assets			0.060
Tier 1 risk based capital to risk weighted assets	0.085
Capital to risk weighted assets	0.105		0.080
Tier 1 capital to average assets of leverage ratio			0.040
Capital conservation buffer rate	2.50%

Shareholders' Equity - Minimum

Shareholders' Equity - Minimum Capital Requirements were Considered Well Capitalized by FRB and FDIC (Details)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jan. 01, 2015
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Total capital (to risk-weighted assets), Actual, Amount	$ 506,239,000	$ 420,398,000
Tier I capital (to risk-weighted assets), Actual, Amount	466,369,000	384,518,000
Common equity tier I capital (to risk-weighted assets), Actual, Amount	466,369,000	384,518,000
Tier I capital (to average assets), Actual, Amount	$ 466,369,000	$ 384,518,000
Total capital (to risk-weighted assets), Actual, Ratio	0.135	0.136
Tier I capital (to risk-weighted assets), Actual, Ratio	0.125	0.124
Common equity tier I capital (to risk-weighted assets), Actual, Ratio	0.125	0.124
Tier I capital (to average assets), Actual, Ratio	0.085	0.083
Total capital (to risk-weighted assets), Minimum Capital Required For Capital Adequacy Plus Capital Conservation Buffer, Amount	$ 393,285,000	$ 325,617,000
Tier I capital (to risk-weighted assets), Minimum Capital Required For Capital Adequacy Plus Capital Conservation Buffer, Amount	318,373,000	263,595,000
Common equity tier I capital (to risk-weighted assets), Minimum Capital Required For Capital Adequacy Plus Capital Conservation Buffer, Amount	262,190,000	217,078,000
Tier I capital (to average assets), Minimum Capital Required For Capital Adequacy Plus Capital Conservation Buffer, Amount	$ 219,309,000	$ 185,015,000
Total capital (to risk-weighted assets), Minimum Capital Required For Capital Adequacy Plus Capital Conservation Buffer, Ratio	0.105	0.105
Tier I capital (to risk-weighted assets), Minimum Capital Required For Capital Adequacy Plus Capital Conservation Buffer, Ratio	0.085	0.085
Common equity tier I capital (to risk-weighted assets), Minimum Capital Required For Capital Adequacy Plus Capital Conservation Buffer, Ratio	0.070	0.070
Tier I capital (to average assets), Minimum Capital Required For Capital Adequacy Plus Capital Conservation Buffer, Ratio	0.040	0.040
Minimum
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Total capital (to risk-weighted assets), Actual, Ratio	0.105		0.080
Tier I capital (to risk-weighted assets), Actual, Ratio	0.085
Tier I capital (to average assets), Actual, Ratio			0.040
Cambridge Trust Company
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Total capital (to risk-weighted assets), Actual, Amount	$ 490,175,000	$ 409,806,000
Tier I capital (to risk-weighted assets), Actual, Amount	450,305,000	373,926,000
Common equity tier I capital (to risk-weighted assets), Actual, Amount	450,305,000	373,926,000
Tier I capital (to average assets), Actual, Amount	$ 450,305,000	$ 373,926,000
Total capital (to risk-weighted assets), Actual, Ratio	0.131	0.132
Tier I capital (to risk-weighted assets), Actual, Ratio	0.120	0.121
Common equity tier I capital (to risk-weighted assets), Actual, Ratio	0.120	0.121
Tier I capital (to average assets), Actual, Ratio	0.082	0.081
Total capital (to risk-weighted assets), Minimum Capital Required For Capital Adequacy Plus Capital Conservation Buffer, Amount	$ 393,246,000	$ 325,587,000
Tier I capital (to risk-weighted assets), Minimum Capital Required For Capital Adequacy Plus Capital Conservation Buffer, Amount	318,342,000	263,570,000
Common equity tier I capital (to risk-weighted assets), Minimum Capital Required For Capital Adequacy Plus Capital Conservation Buffer, Amount	262,164,000	217,058,000
Tier I capital (to average assets), Minimum Capital Required For Capital Adequacy Plus Capital Conservation Buffer, Amount	$ 219,296,000	$ 185,003,000
Total capital (to risk-weighted assets), Minimum Capital Required For Capital Adequacy Plus Capital Conservation Buffer, Ratio	0.105	0.105
Tier I capital (to risk-weighted assets), Minimum Capital Required For Capital Adequacy Plus Capital Conservation Buffer, Ratio	0.085	0.085
Common equity tier I capital (to risk-weighted assets), Minimum Capital Required For Capital Adequacy Plus Capital Conservation Buffer, Ratio	0.070	0.070
Tier I capital (to average assets), Minimum Capital Required For Capital Adequacy Plus Capital Conservation Buffer, Ratio	0.040	0.040
Cambridge Trust Company | Minimum
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Total capital (to risk-weighted assets), Minimum To Be Well-Capitalized Under Prompt Corrective Action Provisions, Amount	$ 374,520,000	$ 310,082,000
Tier I capital (to risk-weighted assets), Minimum To Be Well-Capitalized Under Prompt Corrective Action Provisions, Amount	299,616,000	248,066,000
Common equity tier I capital (to risk-weighted assets), Minimum To Be Well-Capitalized Under Prompt Corrective Action Provisions, Amount	243,438,000	201,554,000
Tier I capital (to average assets), Minimum To Be Well-Capitalized Under Prompt Corrective Action Provisions, Amount	$ 274,120,000	$ 231,254,000
Total capital (to risk-weighted assets), Minimum To Be Well-Capitalized Under Prompt Corrective Action Provisions, Ratio	0.100	0.100
Tier I capital (to risk-weighted assets), Minimum To Be Well-Capitalized Under Prompt Corrective Action Provisions, Ratio	0.080	0.080
Common equity tier I capital (to risk-weighted assets), Minimum To Be Well-Capitalized Under Prompt Corrective Action Provisions, Ratio	0.065	0.065
Tier I capital (to average assets), Minimum To Be Well-Capitalized Under Prompt Corrective Action Provisions, Ratio	0.050	0.050

Comprehensive Income (Loss) - S

Comprehensive Income (Loss) - Summary of Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Available for sale securities, before tax amount
Unrealized holding gains/(losses), before tax amount		$ (25,144)	$ (6,245)	$ 3,630
Reclassification adjustment for (gains)/losses realized in net income, before tax amount	[1]			(73)
Interest rate swaps designated as cash flow hedges, before tax amount
Unrealized holding gains/(losses), before tax amount		(2,170)	(1,329)	6,602
Reclassification adjustment for (gains)/losses recognized in net income, before tax amount	[2]	(832)	(2,587)	(1,879)
Defined benefit retirement plans, before tax amount
Net change in retirement liability, before tax amount		1,818	5,273	(1,695)
Total Other Comprehensive Income/(Loss), before tax amount		(26,328)	(4,888)	6,585
Available for sale securities, tax (expense) or benefit
Unrealized holding gains/(losses),tax (expense) or benefit		6,408	1,623	(830)
Reclassification adjustment for (gains)/losses realized in net income, tax (expense) or benefit	[1]			16
Interest rate swaps designated as cash flow hedges, tax (expense) or benefit
Unrealized holding gains/(losses), tax (expense) or benefit		607	370	(1,844)
Reclassification adjustment for (gains)/losses recognized in net income, tax (expense) or benefit	[2]	232	723	525
Defined benefit retirement plans, tax (expense) or benefit
Net change in retirement liability, tax (expense) or benefit		(508)	(1,472)	463
Total Other Comprehensive Income/(Loss), tax (expense) or benefit		6,739	1,244	(1,670)
Available for sale securities
Unrealized holding gains (losses)		(18,736)	(4,622)	2,800
Reclassification adjustment for losses realized in net income	[1]			(57)
Interest rate swaps designated as cash flow hedges
Unrealized holding gains (losses)		(1,563)	(959)	4,758
Reclassification adjustment for gains (losses) realized in net income	[2]	(600)	(1,864)	(1,354)
Defined benefit retirement plans
Net change in retirement liability, net-of-tax amount		1,310	3,801	(1,232)
Other comprehensive income (loss)		$ (19,589)	$ (3,644)	$ 4,915
[1] Reported in gain (loss) on disposition of investment securities line item in the Consolidated Statements of Income. Reported in interest on payable loans line item in the Consolidated Statements of Income.

Comprehensive Income (Loss) -_2

Comprehensive Income (Loss) - Summary of Components of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income, before tax amount	$ (28,025)	$ (1,697)
Accumulated other comprehensive income, deferred (tax) benefit	7,226	487
Total accumulated other comprehensive income, net-of-tax amount	(20,799)	(1,210)
Available for Sale Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income, before tax amount	(28,611)	(3,467)
Accumulated other comprehensive income, deferred (tax) benefit	7,390	982
Total accumulated other comprehensive income, net-of-tax amount	(21,221)	(2,485)
Interest Rate Swaps Designated as Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income, before tax amount	(14)	2,988
Accumulated other comprehensive income, deferred (tax) benefit	4	(836)
Total accumulated other comprehensive income, net-of-tax amount	(10)	2,152
Defined Benefit Retirement Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income, before tax amount	600	(1,218)
Accumulated other comprehensive income, deferred (tax) benefit	(168)	341
Total accumulated other comprehensive income, net-of-tax amount	$ 432	$ (877)

Earnings Per Share - Summary of

Earnings Per Share - Summary of Reconciliation Between Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Numerator:
Net income	$ 52,909	$ 54,024	$ 31,959
Less dividends and undistributed earnings allocated to participating securities	(257)	(250)	(47)
Net income applicable to common shareholders	$ 52,652	$ 53,774	$ 31,912
Denominator:
Weighted average shares outstanding, basic	7,163,223	6,926,257	6,289,481
Earnings per common share – basic	$ 7.35	$ 7.76	$ 5.07
Numerator:
Net income	$ 52,909	$ 54,024	$ 31,959
Less dividends and undistributed earnings allocated to participating securities	(257)	(250)	(47)
Net income applicable to common shareholders	$ 52,652	$ 53,774	$ 31,912
Denominator:
Weighted average shares outstanding, basic	7,163,223	6,926,257	6,289,481
Dilutive effect of common stock equivalents	51,000	65,000	55,000
Weighted average diluted common shares outstanding	7,213,913	6,990,603	6,344,409
Earnings per common share – diluted	$ 7.30	$ 7.69	$ 5.03

Derivatives And Hedging Activ_3

Derivatives And Hedging Activities - Summary of Fair Values of Derivative Instruments in the Company's Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative Assets, Fair value	$ 52,773	$ 27,051
Derivative Liabilities, Fair value	50,827	23,724
Derivatives Designated as Hedging Instruments
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative Assets, Fair value	1,966	3,513
Derivatives Designated as Hedging Instruments | Interest Rate Contracts
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative Assets, Notional amount	250,000	150,000
Derivatives Designated as Hedging Instruments | Interest Rate Contracts | Other Assets
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative Assets, Fair value	1,966	3,513
Derivatives Not Designated as Hedging Instruments
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative Assets, Fair value	50,807	23,538
Derivative Liabilities, Fair value	50,827	23,724
Derivatives Not Designated as Hedging Instruments | Interest Rate Contracts
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative Assets, Notional amount	499,619	522,581
Derivatives Not Designated as Hedging Instruments | Interest Rate Contracts | Other Assets
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative Assets, Fair value	50,784	23,431
Derivatives Not Designated as Hedging Instruments | Loan Related Derivative Contracts | Interest Rate Contracts One
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative Liabilities, Notional Amount	499,619	522,581
Derivatives Not Designated as Hedging Instruments | Loan Related Derivative Contracts | Interest Rate Contracts One | Other Liabilities
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative Liabilities, Fair value	50,784	23,431
Derivatives Not Designated as Hedging Instruments | Loan Related Derivative Contracts | Risk Participation Agreements Out to Counterparties
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative Assets, Notional amount	46,604	47,988
Derivatives Not Designated as Hedging Instruments | Loan Related Derivative Contracts | Risk Participation Agreements Out to Counterparties | Other Assets
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative Assets, Fair value	23	107
Derivatives Not Designated as Hedging Instruments | Loan Related Derivative Contracts | Risk Participation Agreements with Counterparties
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative Liabilities, Notional Amount	71,046	109,510
Derivatives Not Designated as Hedging Instruments | Loan Related Derivative Contracts | Risk Participation Agreements with Counterparties | Other Liabilities
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative Liabilities, Fair value	$ 43	$ 293

Derivatives And Hedging Activ_4

Derivatives And Hedging Activities - Summary of Cash Flow Hedge Accounting on AOCI (Details) - Cash Flow Hedging - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Interest Income
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Amount of Gain or (Loss) Recognized in OCI - Included Component	$ 1,026	$ 2,782
Amount of Gain or (Loss) Reclassified from AOCI into Income	832	2,587
Amount of Gain or (Loss) Recognized in OCI - Excluded Component	(194)	(195)
Interest Rate Contracts
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Amount of Gain or (Loss) Recognized in OCI	(2,170)	(1,329)
Amount of Gain or (Loss) Recognized in OCI - Included Component	607	370
Amount of Gain or (Loss) Recognized in OCI - Excluded Component	$ (1,563)	$ (959)

Derivatives And Hedging Activ_5

Derivatives And Hedging Activities - Additional Information (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Estimated amount will be reclassified out of AOCI in to earnings	$ 539,000
Fair value of derivative liability	50,827,000	$ 23,724,000
Minimum collateral posting threshold of derivative counterparties	0	13,300,000
Termination amount		14,000,000
Minimum
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Minimum collateral posting threshold of derivative counterparties		13,300,000
Accrued Interest
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Fair value of derivative liability	$ 0	$ 14,000,000

Derivatives And Hedging Activ_6

Derivatives And Hedging Activities - Summary of Derivative Financial Instruments Not Designated as Hedging Instruments on the Consolidated Statements of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Other contracts | Loan related derivative income | Derivatives Not Designated as Hedging Instruments
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	$ (166)	$ (124)	$ 155

Derivatives And Hedging Activ_7

Derivatives And Hedging Activities - Schedule of Financial Instruments Eligible for Offset in Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Offsetting [Abstract]
Gross Amounts Recognized, Derivative assets	$ 52,773	$ 27,051
Net Amounts Recognized, Derivative Assets	$ 52,773	$ 27,051
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other Assets	Other Assets
Gross Amounts Not Offset, Financial Instruments, Derivative Assets	$ 48	$ 6,365
Gross Amounts Not Offset, Net amount, Derivative Assets	595	20,686
Gross Amounts Recognized, Derivative Liabilities	50,827	23,724
Net Amounts Recognized, Derivative Liabilities	$ 50,827	$ 23,724
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Other Liabilities	Other Liabilities
Gross Amounts Not Offset, Financial Instruments, Derivative Liabilities	$ 48	$ 6,365
Gross Amounts Not Offset, Collateral Pledged (Received), Derivative Liabilities		14,011
Gross Amounts Not Offset, Collateral Pledged (Received), Derivative Assets	(52,130)
Gross Amounts Not Offset, Net amount, Derivative Liabilities	$ 50,875	$ 3,348

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Carrying Values and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Financial assets
Securities available for sale	$ 153,416	$ 197,803
Securities held to maturity	885,586	971,092
FHLB of Boston stock	6,264	4,816
Recurring Basis | Carrying Value
Financial assets
Cash and cash equivalents	30,719	180,153
Securities available for sale	153,416	197,803
Securities held to maturity	1,051,997	977,061
Loans, net	4,025,082	3,284,610
Loans held for sale		1,490
FHLB of Boston stock	6,264	4,816
Accrued interest receivable	14,118	9,162
Mortgage servicing rights	1,665	1,083
Interest rate contracts	1,966	3,513
Loan level interest rate swaps	50,784	23,431
Risk participation agreements out to counterparties	23	107
Financial liabilities
Deposits	4,815,376	4,331,152
Borrowings	105,212	16,510
Loan level interest rate swaps	50,784	23,431
Risk participation agreements in with counterparties	43	293
Recurring Basis | Estimated Fair Value
Financial assets
Cash and cash equivalents	30,719	180,153
Securities available for sale	153,416	197,803
Securities held to maturity	885,586	971,092
Loans, net	3,783,051	3,230,339
Loans held for sale		1,528
FHLB of Boston stock	6,264	4,816
Accrued interest receivable	14,118	9,162
Mortgage servicing rights	2,336	1,518
Interest rate contracts	1,966	3,513
Loan level interest rate swaps	50,784	23,431
Risk participation agreements out to counterparties	23	107
Financial liabilities
Deposits	4,810,695	4,330,991
Borrowings	105,202	16,523
Loan level interest rate swaps	50,784	23,431
Risk participation agreements in with counterparties	$ 43	$ 293

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Certain Assets Reported at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available for sale	$ 153,416	$ 197,803
U.S. GSE Obligations
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available for sale	19,733	23,011
Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available for sale	1,000	1,764
Recurring Basis | U.S. GSE Obligations
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available for sale	19,733	23,011
Recurring Basis | U.S. GSE Obligations | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available for sale	19,733	23,011
Recurring Basis | Mortgage-Backed Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available for sale	132,683	173,028
Recurring Basis | Mortgage-Backed Securities | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available for sale	132,683	173,028
Recurring Basis | Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available for sale	1,000	1,764
Recurring Basis | Corporate Debt Securities | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available for sale	1,000	1,764
Recurring Basis | Interest rate swaps with clients
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other assets	50,784	23,431
Recurring Basis | Interest rate swaps with clients | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other assets	50,784	23,431
Recurring Basis | Risk Participation Agreements Out to Counterparties
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other assets	23	107
Recurring Basis | Risk Participation Agreements Out to Counterparties | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other assets	23	107
Recurring Basis | Interest Rate Contracts
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other assets	1,966	3,513
Recurring Basis | Interest Rate Contracts | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other assets	1,966	3,513
Recurring Basis | Interest rate swaps with counterparties
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other liabilities	18,161	23,431
Recurring Basis | Interest rate swaps with counterparties | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other liabilities	50,784	23,431
Recurring Basis | Risk Participation Agreements in With Counterparties
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other liabilities	43	293
Recurring Basis | Risk Participation Agreements in With Counterparties | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other liabilities	$ 43	$ 293

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Carrying Value of Assets Measured at Fair Value on a Non-Recurring Basis (Details) - Non-recurring - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Assets, fair value, non-recurring basis	$ 103	$ 1,620
Level 1
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Assets, fair value, non-recurring basis		1,490
Level 3
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Assets, fair value, non-recurring basis	103	130
Loans Held for Sale
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Assets, fair value, non-recurring basis		1,490
Loans Held for Sale | Level 1
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Assets, fair value, non-recurring basis		1,490
Individually Evaluated Collateral Dependent Loans
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Assets, fair value, non-recurring basis	103	130
Individually Evaluated Collateral Dependent Loans | Level 3
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Assets, fair value, non-recurring basis	$ 103	$ 130

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Transfers between levels	$ 0	$ 0

Condensed Financial Statement_3

Condensed Financial Statements of Parent Company - Condensed Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Assets
Cash and cash equivalents	$ 30,719	$ 180,153
Goodwill	64,539	51,912
Other assets	105,290	76,366
Total assets	5,559,737	4,891,544
Shareholders’ Equity
Total shareholders' equity	517,552	437,837	$ 401,732	$ 286,561
Cambridge Bancorp [Member]
Assets
Cash and cash equivalents	15,747	10,303
Goodwill	33	33
Other assets	318	289
Investment in subsidiary	501,454	427,212
Total assets	517,552	437,837
Shareholders’ Equity
Total shareholders' equity	$ 517,552	$ 437,837

Condensed Financial Statement_4

Condensed Financial Statements of Parent Company - Condensed Statements of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Interest expense
Total interest expense	$ 16,778	$ 5,533	$ 9,145
Income tax benefit	19,052	19,091	11,404
Income of parent company	52,909	54,024	31,959
Net Income	52,909	54,024	31,959
Cambridge Bancorp [Member]
Interest and dividend income
Dividends from subsidiary	24,734	25,995	21,639
Total income	24,734	25,995	21,639
Interest expense
Interest expense			444
Other expenses	148	150	110
Total interest expense	148	150	554
Income before income taxes and equity in undistributed income of subsidiary	24,586	25,845	21,085
Income tax benefit	(40)	(42)	(153)
Income of parent company	24,626	25,887	21,238
Equity in undistributed income of subsidiary	28,283	28,137	10,721
Net Income	$ 52,909	$ 54,024	$ 31,959

Condensed Financial Statement_5

Condensed Financial Statements of Parent Company - Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 52,909	$ 54,024	$ 31,959
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income tax benefit	587	2,899	(665)
Change in other assets, net	32,056	(5,473)	22,863
Change in other liabilities, net	26,260	429	20,332
Net cash provided by operating activities	51,950	65,508	36,797
CASH FLOWS FROM INVESTING ACTIVITIES:
Net cash used in investing activities	(379,183)	(856,462)	(58,928)
CASH FLOWS FROM FINANCING ACTIVITIES:
Redemption of subordinated debt			(10,000)
Cash dividends paid on common stock	(18,414)	(16,554)	(13,083)
Net cash provided by financing activities	177,799	895,322	36,581
Net change in cash and cash equivalents	(149,434)	104,368	14,450
Cash and cash equivalents at beginning of period	180,153	75,785	61,335
Cash and cash equivalents at end of period	30,719	180,153	75,785
Significant non-cash transactions
Common Stock issued to shareholders due to merger	62,850		87,163
Cambridge Bancorp [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	52,909	54,024	31,959
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income tax benefit	(40)	(42)	(153)
Change in other assets, net	12		3,032
Change in other liabilities, net		13	444
Undistributed income of subsidiary	(28,283)	(28,137)	(10,721)
Net cash provided by operating activities	24,598	25,858	24,561
CASH FLOWS FROM INVESTING ACTIVITIES:
Cash paid in business combinations			(534)
Net cash used in investing activities			(534)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from the issuance of common stock	580	519	452
Repurchase of common stock	(1,320)	(1,440)	(556)
Redemption of subordinated debt			(10,600)
Cash dividends paid on common stock	(18,414)	(16,554)	(13,083)
Net cash provided by financing activities	(19,154)	(17,475)	(23,787)
Net change in cash and cash equivalents	5,444	8,383	240
Cash and cash equivalents at beginning of period	10,303	1,920	1,680
Cash and cash equivalents at end of period	15,747	$ 10,303	1,920
Significant non-cash transactions
Common Stock issued to shareholders due to merger	$ 62,850		$ 87,163