Brookline Bancorp (BRKL) 10-K 28 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2018	Feb. 28, 2019	Jun. 30, 2018
Document and Entity Information
Entity Registrant Name	BROOKLINE BANCORP INC
Entity Central Index Key	1,049,782
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 1.5
Entity Common Stock, Shares Outstanding		79,766,511
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Entity Shell Company	false
Entity Emerging Growth Company	false
Entity Small Business	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017
ASSETS
Cash and due from banks		$ 47,542	$ 25,622
Short-term investments		42,042	35,383
Total cash and cash equivalents		89,584	61,005
Investment securities available-for-sale		502,793	539,142
Investment securities available-for-sale			540,124
Investment securities held-to-maturity (fair value of $112,830 and $108,523, respectively)		114,776	109,730
Equity securities held-for-trading		4,207	0
Total investment securities		621,776	649,854
Loans held-for-sale		3,247	2,628
Total loans and leases		6,303,516	5,730,679
Allowance for loan and lease losses		(58,692)	(58,592)
Net loans and leases		6,244,824	5,672,087
Restricted equity securities		61,751	59,369
Premises and equipment, net of accumulated depreciation of $70,140 and $63,423, respectively		76,382	80,283
Deferred tax asset		21,495	15,061
Goodwill		160,427	137,890
Identified intangible assets, net of accumulated amortization of $35,818 and $33,738, respectively		6,086	6,044
Other real estate owned (OREO) and repossessed assets, net		4,019	4,419
Other assets	[1]	103,214	91,609
Total assets		7,392,805	6,780,249
Non-interest-bearing deposits:
Demand checking accounts		1,033,551	942,583
Interest-bearing deposits:
NOW accounts		336,317	350,568
Savings accounts		619,961	646,359
Money market accounts		1,675,050	1,724,363
Certificate of deposit accounts		1,789,165	1,207,470
Total interest-bearing deposits		4,420,493	3,928,760
Total deposits		5,454,044	4,871,343
Borrowed funds:
Advances from the Federal Home Loan Bank of Boston (FHLBB)		784,375	889,909
Subordinated debentures and notes		83,433	83,271
Other borrowed funds		52,734	47,639
Total borrowed funds		920,542	1,020,819
Mortgagors' escrow accounts		7,426	7,686
Accrued expenses and other liabilities		100,174	67,818
Total liabilities		6,482,186	5,967,666
Commitments and contingencies
Brookline Bancorp, Inc. stockholders' equity:
Common stock, $0.01 par value; 200,000,000 shares authorized; 85,177,172 shares issued and 81,695,695 shares issued, respectively		852	817
Additional paid-in capital		755,629	699,976
Retained earnings, partially restricted	[1]	212,838	161,217
Accumulated other comprehensive loss		(9,460)	(5,950)
Treasury stock, at cost; 5,020,025 shares and 4,440,665 shares, respectively		(59,120)	(51,454)
Unallocated common stock held by ESOP; 109,950 shares and 142,332 shares, respectively		(599)	(776)
Total Brookline Bancorp, Inc. stockholders' equity	[1]	900,140	803,830
Noncontrolling interest in subsidiary		10,479	8,753
Total stockholders' equity	[1]	910,619	812,583
Total liabilities and stockholders' equity	[1]	7,392,805	6,780,249
Commercial real estate loans
ASSETS
Total loans and leases		3,351,736	3,075,777
Commercial loans and leases
ASSETS
Total loans and leases		1,768,958	1,624,111
Consumer loans
ASSETS
Total loans and leases		$ 1,182,822	$ 1,030,791
[1]	Previously reported amounts prior to January 1, 2015 have been restated to reflect a retrospective change in accounting principle for investments in qualified affordable housing projects, in accordance with ASU 2014-01. Refer to Note 10, "Other Assets".

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Investment securities held to maturity, fair value	$ 112,830	$ 108,523
Premises and equipment, accumulated depreciation and amortization	70,140	63,423
Identified intangible assets, accumulated amortization	$ 35,818	$ 33,738
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	85,177,172	81,695,695
Treasury stock, shares	5,020,025	4,440,665
Unallocated common stock held by ESOP, shares	109,950	142,332

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest and dividend income:
Loans and leases	$ 295,269	$ 247,022	$ 224,721
Debt securities	13,960	12,524	11,710
Marketable and restricted equity securities	3,964	3,062	2,975
Short-term investments	700	442	242
Total interest and dividend income	313,893	263,050	239,648
Interest expense:
Deposits	41,978	23,288	20,070
Borrowed funds	24,216	16,581	15,914
Total interest expense	66,194	39,869	35,984
Net interest income	247,699	223,181	203,664
Provision for credit losses	4,951	18,988	10,353
Net interest income after provision for credit losses	242,748	204,193	193,311
Non-interest income:
Loan level derivative income, net	5,440	2,187	3,962
Gain on investment securities, net	227	11,393	0
Gain on sales of loans and leases held-for-sale	1,883	2,644	3,256
Other	5,847	4,789	4,683
Total non-interest income	25,224	32,173	22,667
Non-interest expense:
Compensation and employee benefits	91,535	82,413	77,836
Occupancy	14,991	14,546	13,882
Equipment and data processing	18,213	16,854	15,496
Professional services	4,404	4,315	3,852
FDIC insurance	2,722	3,326	3,332
Advertising and marketing	4,016	3,369	3,381
Amortization of identified intangible assets	2,080	2,089	2,500
Merger and acquisition expense	3,787	411	0
Other	13,484	11,788	10,083
Total non-interest expense	155,232	139,111	130,362
Income before provision for income taxes	112,740	97,255	85,616
Provision for income taxes	26,189	43,636	30,392
Net income before noncontrolling interest in subsidiary	86,551	53,619	55,224
Less net income attributable to noncontrolling interest in subsidiary	3,489	3,101	2,862
Net income attributable to Brookline Bancorp, Inc.	$ 83,062	$ 50,518	$ 52,362
Earnings per common share:
Basic (in dollars per share)	$ 1.04	$ 0.68	$ 0.74
Diluted (in dollars per share)	$ 1.04	$ 0.68	$ 0.74
Weighted average common shares outstanding during the year:
Basic (in shares)	79,669,668	74,459,508	70,261,954
Diluted (in shares)	79,909,251	74,811,408	70,444,083
Dividends declared per common share (in dollars per share)	$ 0.395	$ 0.36	$ 0.360
Deposit fees
Non-interest income:
Non-interest income, fees	$ 10,400	$ 10,050	$ 9,467
Loan fees
Non-interest income:
Non-interest income, fees	$ 1,427	$ 1,110	$ 1,299

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income before noncontrolling interest in subsidiary	$ 86,551	$ 53,619	$ 55,224
Investment securities available-for-sale:
Unrealized securities holding losses	(4,444)	(1,274)	(2,167)
Income tax benefit	980	457	781
Net unrealized securities holding losses before reclassification adjustments	(3,464)	(817)	(1,386)
Less reclassification adjustments for securities gains included in net income:
Gain on sales of securities, net	173	0	0
Income tax expense	(38)	0	0
Net reclassification adjustments for securities gains included in net income	135	0	0
Net unrealized securities holding losses	(3,599)	(817)	(1,386)
Postretirement benefits:
Adjustment of accumulated obligation for postretirement benefits	121	(422)	69
Income tax benefit (expense)	(32)	170	(25)
Net adjustment of accumulated obligation for postretirement benefits	89	(252)	44
Other comprehensive loss, net of taxes	(3,510)	(1,069)	(1,342)
Comprehensive income	83,041	52,550	53,882
Net income attributable to noncontrolling interest in subsidiary	3,489	3,101	2,862
Comprehensive income attributable to Brookline Bancorp, Inc.	$ 79,552	$ 49,449	$ 51,020

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total		Total Brookline Bancorp, Inc. Stockholders' Equity	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock	Unallocated Common Stock Held by ESOP	Noncontrolling Interest in Subsidiary
Balance beginning of period at Dec. 31, 2015	$ 673,486		$ 667,485	$ 757	$ 616,899	$ 109,675	$ (2,476)	$ (56,208)	$ (1,162)	$ 6,001
Increase (Decrease) in Stockholders' Equity
Net income attributable to Brookline Bancorp, Inc.	52,362		52,362			52,362
Net income attributable to noncontrolling interest in subsidiary	2,862									2,862
Issuance of noncontrolling interest	76									76
Other comprehensive loss	(1,342)		(1,342)				(1,342)
Common stock dividends	(25,366)		(25,366)			(25,366)
Dividend distribution to owners of noncontrolling interest in subsidiary	(1,734)									(1,734)
Compensation under recognition and retention plans	2,010		2,010		(361)			2,371
Common stock held by ESOP committed to be released	395		395		196				199
Balance end of period at Dec. 31, 2016	702,749		695,544	757	616,734	136,671	(3,818)	(53,837)	(963)	7,205
Increase (Decrease) in Stockholders' Equity
Reclassification due to the adoption of ASU No. 2018-02	1,100				(1,063)	1,063	(1,063)
Net income attributable to Brookline Bancorp, Inc.	50,518		50,518			50,518
Net income attributable to noncontrolling interest in subsidiary	3,101									3,101
Issuance of common stock	81,943		81,943	60	81,883
Issuance of noncontrolling interest	118									118
Other comprehensive loss	(1,069)		(1,069)				(1,069)
Common stock dividends	(27,035)		(27,035)			(27,035)
Dividend distribution to owners of noncontrolling interest in subsidiary	(1,671)									(1,671)
Compensation under recognition and retention plans	3,428		3,428		1,045			2,383
Common stock held by ESOP committed to be released	501		501		314				187
Balance end of period at Dec. 31, 2017	812,583	[1]	803,830	817	699,976	161,217	(5,950)	(51,454)	(776)	8,753
Increase (Decrease) in Stockholders' Equity
Net income attributable to Brookline Bancorp, Inc.	83,062		83,062			83,062
Net income attributable to noncontrolling interest in subsidiary	3,489									3,489
Common stock issued for acquisition	55,183		55,183	35	55,148
Issuance of noncontrolling interest	130									130
Other comprehensive loss	(3,510)		(3,510)				(3,510)
Common stock dividends	(31,441)		(31,441)			(31,441)
Dividend distribution to owners of noncontrolling interest in subsidiary	(1,893)									(1,893)
Restricted stock awards, net of awards surrendered	2,473		2,473		139			2,334
Treasury stock, repurchase shares	(10,000)		(10,000)					(10,000)
Common stock held by ESOP committed to be released	543		543		366				177
Balance end of period at Dec. 31, 2018	$ 910,619	[1]	$ 900,140	$ 852	$ 755,629	$ 212,838	$ (9,460)	$ (59,120)	$ (599)	$ 10,479
[1]	Previously reported amounts prior to January 1, 2015 have been restated to reflect a retrospective change in accounting principle for investments in qualified affordable housing projects, in accordance with ASU 2014-01. Refer to Note 10, "Other Assets".

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Stockholders' Equity [Abstract]
Common stock dividends, per share (in dollars per share)	$ 0.395	$ 0.36	$ 0.360
Common stock held by ESOP committed to be released, shares	32,382	34,356	36,372

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income attributable to Brookline Bancorp, Inc.	$ 83,062	$ 50,518	$ 52,362
Adjustments to reconcile net income to net cash provided from operating activities:
Net income attributable to noncontrolling interest in subsidiary	3,489	3,101	2,862
Provision for credit losses	4,951	18,988	10,353
Origination of loans and leases held-for-sale	(25,370)	(27,425)	(56,080)
Proceeds from sales of loans and leases held-for-sale, net	26,519	32,073	55,636
Deferred income tax (benefit) expense	(5,453)	10,798	2,322
Depreciation of premises and equipment	7,382	7,232	7,080
Amortization of investment securities premiums and discounts, net	2,200	2,042	2,158
Amortization of deferred loan and lease origination costs, net	6,971	6,695	5,883
Amortization of identified intangible assets	2,080	2,089	2,500
Amortization of debt issuance costs	100	100	101
Amortization (accretion) of acquisition fair value adjustments, net	354	(1,583)	(3,960)
Gain on sales of investment securities, net	(227)	(11,393)	0
Gain on sales of loans and leases held-for-sale	(1,883)	(2,644)	(3,256)
Gain on sales of OREO and other repossessed assets, net	0	(79)	(84)
Write-down of OREO and other repossessed assets	1,234	458	190
Compensation under recognition and retention plans	2,546	2,308	1,844
ESOP shares committed to be released	543	501	395
Net change in:
Cash surrender value of bank-owned life insurance	(1,039)	(1,041)	(1,050)
Equity securities held-for-trading	(5,371)	0	0
Other assets	(10,855)	(2,413)	(287)
Accrued expenses and other liabilities	31,796	(5,378)	(1,039)
Net cash provided from operating activities	123,029	84,947	77,930
Cash flows from investing activities:
Proceeds from sales of investment securities available-for-sale	22,210	0	0
Proceeds from maturities, calls, and principal repayments of investment securities available-for-sale	82,896	71,611	100,957
Purchases of investment securities available-for-sale	(73,852)	(90,971)	(115,403)
Proceeds from maturities, calls, and principal repayments of investment securities held to maturity	3,290	3,817	42,492
Purchases of investment securities held-to-maturity	(8,915)	(26,873)	(36,167)
Proceeds from redemption/sales of restricted equity securities	12,110	24,462	5,623
Purchase of restricted equity securities	(13,262)	(7,927)	(4,017)
Proceeds from sales of loans and leases held-for-investment, net	7,294	28,608	45,979
Net increase in loans and leases	(593,968)	(378,906)	(465,527)
Acquisitions, net of cash and cash equivalents acquired	(24,659)	0	0
Purchase of premises and equipment, net	(3,352)	(11,557)	(5,262)
Proceeds from sales of OREO and other repossessed assets	2,186	3,762	3,530
Net cash used for investing activities	(588,022)	(383,974)	(427,795)
Cash flows from financing activities:
Increase in demand checking, NOW, savings and money market accounts	1,006	93,819	351,908
Increase (decrease) in certificates of deposit	580,878	166,448	(46,752)
Proceeds from FHLBB advances	6,607,745	4,685,706	5,905,511
Repayment of FHLBB advances	(6,713,279)	(4,705,543)	(5,854,019)
Increase (decrease) in other borrowed funds, net	5,095	(2,568)	11,980
(Decrease) increase in mortgagors' escrow accounts, net	(260)	41	129
Proceeds from exercise of stock options	490	1,469	300
Repurchases of common stock	(10,000)	0	0
Proceeds from issuance of common stock	0	81,943	0
Common stock issued for acquisition	55,182	0	0
Payment of dividends on common stock	(31,441)	(27,035)	(25,366)
Payment of income taxes for shares withheld in share based activity	(81)	(352)	0
Proceeds from issuance of noncontrolling units	130	118	76
Payment of dividends to owners of noncontrolling interest in subsidiary	(1,893)	(1,671)	(1,734)
Net cash provided from financing activities	493,572	292,375	342,033
Net increase (decrease) in cash and cash equivalents	28,579	(6,652)	(7,832)
Cash and cash equivalents at beginning of year	61,005	67,657	75,489
Cash and cash equivalents at end of year	89,584	61,005	67,657
Cash paid during the year for:
Interest on deposits, borrowed funds and subordinated debt	65,182	40,785	38,620
Income taxes	21,129	34,026	29,770
Non-cash investing activities:
Transfer from loans and leases to loan and leases held-for-sale	0	7,500	2,500
Transfer from loans to other real estate owned	3,020	7,161	3,692
Fair value of assets acquired, net of cash and cash equivalents acquired	292,025	0	0
Fair value of liabilities assumed	$ 278,988	$ 0	$ 0

Basis of Presentation

Basis of Presentation	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation Overview Brookline Bancorp, Inc. (the "Company") is a bank holding company (within the meaning of the Bank Holding Company Act of 1956, as amended) and the parent of Brookline Bank, a Massachusetts-chartered savings bank; Bank Rhode Island ("BankRI"), a Rhode Island-chartered financial institution; and First Ipswich Bank ("First Ipswich"), a Massachusetts-chartered trust company (collectively referred to as the "Banks"). The Banks are all members of the Federal Reserve System. The Company is also the parent of Brookline Securities Corp. ("BSC"). The Company's primary business is to provide commercial, business and retail banking services to its corporate, municipal and retail customers through the Banks and its non-bank subsidiaries. On March 1, 2018, the Company completed the Transaction of First Commons Bank. First Commons Bank was merged with and into Brookline Bank. First Commons Bank had two branch locations in Newton Centre and Wellesley, Massachusetts. These branch locations were closed on June 1, 2018 and consolidated into Brookline Bank's existing branch locations in Newton Centre and Wellesley. The Transaction included $262.3 million in loans and $273.7 million in deposits at fair value. The Transaction qualified as a tax-free reorganization for federal income tax purposes. The total Transaction consideration was $56.0 million . For each share of the Company's common stock, First Commons Bank shareholders received the right to receive 1.089 shares of the Company's common stock with cash in lieu of fractional shares, options, and warrants, resulting in a total cash consideration payment of $851 thousand and an increase in the Company's outstanding shares of 3,481,477 shares. Brookline Bank, which includes its wholly-owned subsidiaries BBS Investment Corp., Longwood Securities Corp., and its 84.07% owned subsidiary, Eastern Funding LLC ("Eastern Funding"), operates 25 full-service banking offices in the greater Boston metropolitan area with two additional lending offices. BankRI, which includes its wholly-owned subsidiaries, Acorn Insurance Agency, BRI Realty Corp., Macrolease Corporation ("Macrolease"), BRI Investment Corp. and its wholly-owned subsidiary, BRI MSC Corp., operates 20 full-service banking offices in the greater Providence, Rhode Island area. First Ipswich, which includes its wholly-owned subsidiaries, First Ipswich Insurance Agency and First Ipswich Securities II Corp., operates six full-service banking offices on the north shore of eastern Massachusetts. The Company's activities include acceptance of commercial, municipal and retail deposits, origination of mortgage loans on commercial and residential real estate located principally in all New England states, origination of commercial loans and leases to small- and mid-sized businesses, investment in debt and equity securities, and the offering of cash management and investment advisory services. The Company also provides specialty equipment financing through its subsidiaries Eastern Funding, which is based in New York City, New York, and Macrolease, which is based in Plainview, New York. The Company and the Banks are supervised, examined and regulated by the Board of Governors of the Federal Reserve System ("FRB"). As a Massachusetts-chartered savings bank and trust company respectively, Brookline Bank and First Ipswich are also subject to regulation under the laws of the Commonwealth of Massachusetts and the jurisdiction of the Massachusetts Division of Banks. As a Rhode Island-chartered financial institution, BankRI is subject to regulation under the laws of the State of Rhode Island and the jurisdiction of the Banking Division of the Rhode Island Department of Business Regulation. The Federal Deposit Insurance Corporation ("FDIC") offers insurance coverage on all deposits up to $250,000 per depositor at each of the Banks. As FDIC-insured depository institutions, the Banks are also secondarily subject to supervision, examination and regulation by the FDIC. Additionally, as a Massachusetts-chartered savings bank, the deposits of Brookline Bank are insured by the Depositors Insurance Fund ("DIF"), a private industry-sponsored insurance company. The DIF insures savings bank deposits in excess of the FDIC insurance limits. As such, Brookline Bank offers 100% insurance on all deposits as a result of a combination of insurance from the FDIC and the DIF. Brookline Bank is required to file reports with the DIF. Basis of Financial Statement Presentation The Company's consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles ("GAAP") as set forth by the Financial Accounting Standards Board ("FASB") in its Accounting Standards Codification and through the rules and interpretive releases of the Securities and Exchange Commission ("SEC") under the authority of federal securities laws. The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All significant intercompany transactions and balances are eliminated in consolidation. In preparing these consolidated financial statements, management is required to make significant estimates and assumptions that affect the reported amounts of assets, liabilities, income, expenses and disclosure of contingent assets and liabilities. Actual results could differ from those estimates based upon changing conditions, including economic conditions and future events. Material estimates that are particularly susceptible to significant changes in the near-term include the determination of the allowance for loan and lease losses, the determination of fair market values of assets and liabilities, including acquired loans, the review of goodwill and intangibles for impairment and the review of deferred tax assets for valuation allowance. The judgments used by management in applying these critical accounting policies may be affected by a further and prolonged deterioration in the economic environment, which may result in changes to future financial results. For example, subsequent evaluations of the loan and lease portfolio, in light of the factors then prevailing, may result in significant changes in the allowance for loan and lease losses in future periods, and the inability to collect outstanding principal may result in increased loan and lease losses. Reclassification Certain previously reported amounts have been reclassified to conform to the current year's presentation. Cash and Cash Equivalents For purposes of reporting asset balances and cash flows, cash and cash equivalents includes cash on hand and due from banks (including cash items in process of clearing), interest-bearing deposits with banks, federal funds sold, money market mutual funds and other short-term investments with original maturities of three months or less. Investment Securities Investment securities, other than those reported as short-term investments, are classified at the time of purchase as "available-for-sale," "held-to-maturity," or "held-for-trading." Classification is periodically re-evaluated for consistency with the Company's goals and objectives. Equity investments in the Federal Home Loan Bank of Boston ("FHLBB"), the Federal Reserve Bank of Boston and other restricted equities are discussed in more detail in Note 5, "Restricted Equity Securities." Investment Securities Available-for-Sale, Held-to-Maturity, and Held-for-Trading Investment securities for which the Company has the positive intent and ability to hold to maturity are classified as held-to-maturity and carried at amortized cost. Those investment securities held for indefinite periods of time but not necessarily to maturity are classified as available-for-sale. Investment securities held for indefinite periods of time include investment securities that management intends to use as part of its asset/liability, liquidity, and/or capital management strategies and may be sold in response to changes in interest rates, maturities, asset/liability mix, liquidity needs, regulatory capital needs or other business factors. Investment securities available-for-sale are carried at estimated fair value, primarily obtained from a third-party pricing service, with unrealized gains and losses reported on an after-tax basis in stockholders' equity as accumulated other comprehensive income or loss. Investment securities expected to be held for very short term duration, used for hedging, or are marketable equity securities are typically designated held-for-trading. Held-for-trading securities are carried at estimated fair value principally based on market prices and dealer quotes received from third-party and nationally-recognized pricing services. Gains and losses for held-for-trading are reported on the income statement as gains on investment securities, net. As of December 31, 2018 and 2017 , the Company did not make any adjustments to the prices provided by the third-party pricing service. Security transactions are recorded on the trade date. Realized gains and losses are determined using the specific identification method and are recorded in non-interest income. Interest and dividends on securities are recorded using the accrual method. Premiums and discounts on securities are amortized or accreted into interest income using the level-yield method over the remaining period to contractual maturity, adjusted for the effect of actual prepayments in the case of mortgage-backed securities ("MBSs") and collateralized mortgage obligations ("CMOs"). These estimates of prepayment assumptions are made based upon the actual performance of the underlying security, current interest rates, the general market consensus regarding changes in mortgage interest rates, the contractual repayment terms of the underlying loans, the priority rights of the investors to the cash flows from the mortgage securities and other economic conditions. When differences arise between anticipated prepayments and actual prepayments, the effective yield is recalculated to reflect actual payments to date and anticipated future payments. Unamortized premium or discount is adjusted to the amount that would have existed had the new effective yield been applied since purchase, with a corresponding charge or credit to interest income. Management evaluates securities for other-than-temporary impairment ("OTTI") on a periodic basis. Factors considered in determining whether an impairment is OTTI include: (1) the length of time and the extent to which the fair value has been less than amortized cost, (2) projected future cash flows, (3) the financial condition and near-term prospects of the issuers, and (4) the intent and ability of the Company to hold the investment for a period of time sufficient to allow for any anticipated recovery in fair value. The Company records an OTTI loss in an amount equal to the entire difference between the fair value and amortized cost if: (1) the Company intends to sell an impaired investment security, (2) it is more likely than not that the Company will be required to sell the investment security before its amortized cost, or (3) for debt securities, the present value of expected future cash flows is not sufficient to recover the entire amortized cost basis. If an investment security is determined to be OTTI but the Company does not intend to sell the investment security, only the credit portion of the estimated loss is recognized in earnings, with the non credit portion of the loss recognized in other comprehensive income. Restricted Equity Securities The Company invests in the stock of the FHLBB, the Federal Reserve Bank of Boston and a small amount of other restricted securities. No ready market exists for these stocks, and they have no quoted market values. The Banks, as members of the FHLBB, are required to maintain investments in the capital stock of the FHLBB equal to their membership base investments plus an activity-based investment determined according to the Banks' level of outstanding FHLBB advances. Federal Reserve Bank of Boston stock was purchased and is redeemable at par. The Company reviews for impairment of these securities based on the ultimate recoverability of the cost basis in the stock. As of December 31, 2018 and 2017 , no impairment has been recognized. Loans Originated Loans Loans the Company originates for the portfolio, and for which it has the intent and ability to hold to maturity, are reported at amortized cost, inclusive of deferred loan origination fees and expenses, less unadvanced funds due borrowers on loans and the allowance for loan and lease losses. Interest income on loans and leases originated for the portfolio is accrued on unpaid principal balances as earned. Loan origination fees and direct loan origination costs are deferred, and the net fee or cost is recognized in interest income using the interest method. Deferred amounts are recognized for fixed-rate loans over the contractual life of the loans and for adjustable-rate loans over the period of time required to adjust the contractual interest rate to a yield approximating a market rate at the origination date. If a loan is prepaid, the unamortized portion of the loan origination costs, including third party referral related costs not subject to rebate from the dealer, is charged to income. Loans and Leases Held-for-Sale Management identifies and designates certain newly originated loans and leases for sale to specific financial institutions, subject to the underwriting criteria of those financial institutions. These loans and leases are held for sale and are carried at the lower of cost or market as determined in the aggregate. Deferred loan fees and costs are included in the determination of the gain or loss on sale. Acquired Loans Acquired loans that have evidence of deterioration of credit quality since origination and for which it is probable, at acquisition, that the Company will be unable to collect all contractually required payments receivable are initially recorded at fair value (as determined by the present value of expected future cash flows) with no valuation allowance. The difference between the undiscounted cash flows expected at acquisition and the recorded fair value of the loan, or the “accretable yield,” is recognized as interest income on a level-yield method over the life of the loan. Contractually required payments for interest and principal that exceed the undiscounted cash flows expected at acquisition, or the “nonaccretable difference,” are not recognized as a yield adjustment or as a loss accrual or a valuation allowance. Increases in expected cash flows subsequent to the initial investment are recognized prospectively through adjustment of the yield on the loan over its remaining life. Decreases in expected cash flows are recognized as impairment. Valuation allowances on these impaired loans reflect only losses incurred after the acquisition (meaning the present value of all cash flows expected at acquisition that ultimately are not to be received). For the First Commons Bank portfolio, minimal loss is expected from the loan portfolio based on historical performance, management’s due diligence, and market conditions. Therefore, the fair value of the loan portfolio was calculated on an individual loan basis using a discounted cash flow analysis factoring in the contractual terms of the loans, current market pricing, and prepayment expectations. Nonperforming Loans Nonaccrual Loans Accrual of interest on loans generally is discontinued when contractual payment of principal or interest becomes past due 90 days or, if in management's judgment, reasonable doubt exists as to the full timely collection of interest. Exceptions may be made if the loan has matured and is in the process of renewal or is well-secured and in the process of collection. When a loan is placed on nonaccrual status, interest accruals cease and uncollected accrued interest is reversed and charged against current interest income. Interest payments on nonaccrual loans are generally applied to principal. If collection of the principal is reasonably assured, interest payments are recognized as income on the cash basis. Loans are generally returned to accrual status when principal and interest payments are current, full collectability of principal and interest is reasonably assured and a consistent record of at least six consecutive months of performance has been achieved. Impaired Loans A loan is considered to be impaired when, based on current information and events, it is probable that the Company will be unable to collect all amounts due (both interest and principal) according to the contractual terms of the loan agreement. Smaller-balance, homogeneous loans that are evaluated collectively for impairment, such as residential, home equity and other consumer loans are specifically excluded from the impaired loan portfolio except where the loan is classified as a troubled debt restructuring. The Company has defined the population of impaired loans to include nonaccrual loans and troubled debt restructured ("TDR") loans. When the ultimate collectability of the total principal of an impaired loan or lease is in doubt and the loan is on nonaccrual status, all payments are applied to principal, under the cost recovery method. When the ultimate collectability of the total principal of an impaired loan or lease is not in doubt and the loan or lease is on nonaccrual status, contractual interest is credited to interest income when received, under the cash basis method. The value of an impaired loan is measured based upon the present value of expected future cash flows discounted at the loan's effective interest rate, or the fair value of the collateral if the loan is collateral-dependent and its payment is expected solely based on the underlying collateral. For impaired loans deemed collateral dependent, where impairment is measured using the fair value of the collateral, the Company will either obtain a new appraisal or use another available source of collateral assessment to determine a reasonable estimate of the fair value of the collateral. Interest collected on impaired loans is either applied against principal or reported as income according to management's judgment as to the collectability of principal. If management does not consider a loan ultimately collectible within an acceptable time frame, payments are applied as principal to reduce the loan balance. If full collection of the remaining recorded investment should subsequently occur, interest receipts are recorded as interest income on a cash basis. Troubled Debt Restructured Loans In cases where a borrower experiences financial difficulties and the Company makes certain concessionary modifications to contractual terms, the loan is classified as a TDR loan. In determining whether a debtor is experiencing financial difficulties, the Company considers, among other factors, whether the debtor is in payment default or is likely to be in payment default in the foreseeable future without the modification, if the debtor declared or is in the process of declaring bankruptcy, there is substantial doubt that the debtor will continue as a going concern, the debtor's entity-specific projected cash flows will not be sufficient to service its debt, or the debtor cannot obtain funds from sources other than the existing creditors at market terms for debt with similar risk characteristics. Large groups of small-balance homogeneous loans such as residential real estate, residential construction, home equity and other consumer portfolios are collectively evaluated for impairment. As such, the Company does not typically identify individual loans within these groupings as impaired loans or for impairment evaluation and disclosure. However, the Company evaluates all TDRs for impairment on an individual loan basis regardless of loan type. Modifications may include interest-rate reductions, short-term (defined as one year or less) changes in payment structure to interest-only payments, short-term extensions of the loan's original contractual term, or less frequently, principal forgiveness, interest capitalization, forbearance and other actions intended to minimize economic loss and avoid foreclosure or repossession of collateral. Typically, TDRs are placed on nonaccrual status and reported as nonperforming loans. Generally, a nonaccrual loan that is restructured remains on nonaccrual for a period of six months to demonstrate that the borrower can meet the restructured terms; however, performance prior to the restructuring, or significant events that coincide with the restructuring, are considered in assessing whether the borrower can meet the new terms and may result in the loan being returned to accrual status at the time of restructuring or after a shorter performance period. If the borrower's ability to meet the revised payment schedule is not reasonably assured, the loan remains classified as a nonaccrual loan. Loans restructured at an interest rate equal to or greater than that of a new loan with comparable risk at the time the loan agreement is modified may be excluded from restructured loan disclosures in years subsequent to the restructuring if they are in compliance with the modified terms. Allowance for Loan and Lease Losses Management has established a methodology to determine the adequacy of the allowance for loan and lease losses that assesses the risks and losses inherent in the loan and lease portfolio. Additions to the allowance for loan and lease losses are made by charges to the provision for credit losses. Losses on loans and leases are charged off against the allowance when all or a portion of a loan or lease is considered uncollectible. Subsequent recoveries on loans previously charged off, if any, are credited to the allowance when realized. Management uses a consistent and systematic process and methodology to evaluate the adequacy of the allowance for loan and lease losses on a quarterly basis. For purposes of determining the allowance for loan and lease losses, the Company has segmented certain loans and leases in the portfolio by product type into the following segments: (1) commercial real estate loans, (2) commercial loans and leases, (3) and consumer loans. Portfolio segments are further disaggregated into classes based on the associated risks within the segments. Commercial real estate loans are divided into three classes: commercial real estate mortgage loans, multi-family mortgage loans, and construction loans. Commercial loans and leases are divided into three classes: commercial loans which includes taxi medallion loans, equipment financing, and loans to condominium associations. Consumer loans are divided into three classes: residential mortgage loans, home equity loans, and other consumer loans. A formula-based credit evaluation approach is applied to each group, coupled with an analysis of certain loans for impairment. The general allowance related to loans collectively evaluated for impairment is determined using a formula-based approach utilizing the risk ratings of individual credits and loss factors derived from historic portfolio loss rates, which include estimates of incurred losses over an estimated loss emergence period (“LEP”). The LEP was generated utilizing a charge-off look-back analysis which studied the time from the first indication of elevated risk of repayment (or other early event indicating a problem) to eventual charge-off to support the LEP considered in the allowance calculation. This reserving methodology established the approximate number of months of LEP that represents incurred losses for each portfolio. In addition to quantitative measures, relevant qualitative factors include, but are not limited to: (1) levels and trends in past due and impaired loans, (2) levels and trends in charge-offs, (3) changes in underwriting standards, policy exceptions, and credit policy, (4) experience of lending management and staff, (5) economic trends, (6) industry conditions, (7) effects of changes in credit concentrations, (8) interest rate environment, and (9) regulatory and other changes. The general allowance related to the acquired loans collectively evaluated for impairment is determined based upon the degree, if any, of deterioration in the pooled loans subsequent to acquisition. The qualitative factors used in the determination are the same as those used for originated loans. During 2015, the Company enhanced and refined its general allowance methodology. Under the enhanced methodology, management combined the historical loss histories of the Banks to generate a single set of historical loss ratios. Management believes it is appropriate to aggregate the ratios as the Banks share common environmental factors, operate in similar geographic markets, and utilize common underwriting standards in accordance with the Company's Credit Policy. In prior periods, a historical loss history applicable to each Bank was used. Management employed a similar analysis for the consolidation of the qualitative factors as it did for the quantitative factors. Again, management believes the realignment of the existing nine qualitative factors used at each of the Banks into a single group of factors used for the Company is appropriate based on the commonality of environmental factors, markets and underwriting standards among the Banks. Prior to 2015, each of the Banks utilized a set of qualitative factors applicable to each Bank. The Company’s December 31, 2018 allowance calculation included a further segmentation of the commercial loans and leases to reflect the increased risk in the Company’s taxi medallion portfolio. As of December 31, 2018 , this portfolio is approximately $13.7 million . Based on industry conditions, management established a loss factor for this portfolio that best represents the changing risks associated with it. Based on the refinements to the Company’s allowance methodology discussed above, management determined that the potential risks anticipated by the unallocated allowance are now incorporated into the allowance methodology, making the unallocated allowance unnecessary. Prior to 2015, the unallocated allowance was used to recognize the estimated risk associated with the allocated general and specific allowances. It incorporated management’s evaluation of existing conditions that were not included in the allocated allowance determinations and provided for losses that arise outside of the ordinary course of business. Specific valuation allowances are established for impaired originated loans with book values greater than the discounted present value of expected future cash flows or, in the case of collateral-dependent impaired loans, for any excess of a loan's book balance and the fair value of its underlying collateral. Specific valuation allowances are established for acquired loans with deterioration in the discounted present value of expected future cash flows since acquisitions or, in the case of collateral dependent impaired loans, for any increase in the excess of a loan's book balance greater than the fair value of its underlying collateral. A specific valuation allowance for losses on TDR loans is determined by comparing the net carrying amount of the troubled debt restructured loan with the restructured loan's cash flows discounted at the original effective rate. Impaired loans are reviewed quarterly with adjustments made to the calculated reserve as necessary. As of December 31, 2018 , management believes that the methodology for calculating the allowance is sound and that the allowance provides a reasonable basis for determining and reporting on probable losses in the Company’s loan portfolios. Liability for Unfunded Commitments In the ordinary course of business, the Company enters into commitments to extend credit, commercial letters of credit, and standby letters of credit. Such financial instruments are recorded in the financial statements when they become payable. The credit risk associated with these commitments is evaluated in a manner similar to the allowance for loan losses. Premises and Equipment Premises and equipment are carried at cost less accumulated depreciation and amortization, except for land which is carried at cost. Premises and equipment are depreciated using the straight-line method over the estimated useful life of the assets. Leasehold improvements are amortized using the straight-line method over the shorter of the lease term or the estimated useful life of the improvements. Costs related to internal-use software development projects that provide significant new functionality are capitalized. Internal-use software is software acquired or modified solely to meet the Company's needs and for which there is no plan to market the software externally. Direct and indirect costs associated with the application development stage of internal use software are capitalized until such time that the software is substantially complete and ready for its intended use. Capitalized costs are amortized on a straight-line basis over the remaining estimated life of the software. Computer software and development costs incurred in the preliminary project stage, as well as training and maintenance costs, are expensed as incurred. Leases The Company leases properties for offices and branches in the states of Massachusetts, Rhode Island and New York. Lease terms range from five years to over 25 years with options to renew. Management performs an analysis to determine proper lease accounting at lease inception and for each renewal. If a lease meets any of the following four criteria, the lease is classified as capital lease. The four criteria are: transfer of ownership by the end of lease term; contains bargain purchase option; lease term is at least 75% of the property’s estimated remaining economic life; or present value of the minimum lease payment is at least 90% of the fair value of the leased property. All leases are classified as operating leases and rental payments are expensed as incurred. Certain leases contain rent escalation clauses which are amortized over the life of the lease under the straight-line method. Bank-Owned Life Insurance The Company acquired bank-owned life insurance ("BOLI") plans as part of its acquisitions of First Ipswich and BankRI. BOLI represents life insurance on the lives of certain current and former employees who have provided positive consent allowing their employer to be the beneficiary of such policies. BankRI and First Ipswich are the beneficiaries of their respective policies. BankRI and First Ipswich utilize BOLI as tax-efficient financing for their benefit obligations to their employees, including their retirement obligations and Supplemental Executive Retirement Plans ("SERPs"). Since BankRI and First Ipswich are the primary beneficiaries of their respective insurance policies, increases in the cash value of the policies, as well as insurance proceeds received, are recorded in non-interest income and are not subject to income taxes. BOLI is recorded at the cash value of the policies, less any applicable cash surrender charges, and is reflected as an asset in the accompanying consolidated balance sheets. Cash proceeds, if any, are classified as cash flows from investing activities. The Company reviews the financial strength of the insurance carriers prior to the purchase of BOLI to ensure minimum credit ratings of at least investment grade. The financial strength of the carriers is reviewed at least annually, and BOLI with any individual carrier is limited to 10% of the Company's capital. Total BOLI is limited to 25% of the Company's capital. Goodwill and Other Identified Intangible Assets Goodwill represents the excess of the cost of an acquisition over the fair value of the net assets acquired. Goodwill and indefinite-lived identified intangible assets are not subject to amortization. Definite-lived identified intangible assets are assets resulting from acquisitions that are being amortized over their estimated useful lives. The recoverability of goodwill and identified intangible assets is evaluated for impairment at least annually. As part of this evaluation, the Company makes a qualitative assessment of whether it is more likely than not that the fair value of an acquired asset is greater than its carrying amount. If the Company qualitatively concludes that it is more likely than not that the fair value of an acquired asset is greater than its carrying amount, no further testing is necessary. If, however, the Company qualitatively concludes that the fair value

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Acquisitions	Acquisitions First Commons Bank, N.A. On March 1, 2018, the Company completed the Transaction of First Commons Bank. First Commons Bank was merged with and into the Company’s subsidiary bank, Brookline Bank. First Commons Bank had two branch locations in Newton Centre and Wellesley, Massachusetts. These branch locations were closed on June 1, 2018 and consolidated into Brookline Bank’s existing branch locations in Newton Centre and Wellesley, Massachusetts. The Transaction qualified as a tax-free reorganization for federal income tax purposes. The total Transaction consideration was $56.0 million . First Commons Bank stockholders received, for each share of First Commons Bank common stock, the right to receive 1.089 shares of the Company’s common stock with cash in lieu of fractional shares, options, and warrants, resulting in a total cash consideration payment of $851 thousand and an increase to the Company’s outstanding shares of 3,481,477 shares. The Company accounted for the Transaction using the estimated fair value of assets and liabilities assumed as of the acquisition date. The excess of consideration paid over the fair value of identifiable net assets was recorded as goodwill in the consolidated financial statements. Accordingly, the Company recorded merger and acquisition expenses for First Commons Bank of $3.6 million during the twelve months ended December 31, 2018 . The following table summarizes the estimated fair value of the assets acquired and liabilities assumed as of the date of the acquisition: Net Assets Acquired at Fair Value (In Thousands) ASSETS Cash $ 42,995 Restricted stock 1,884 Loans 262,304 Premises and equipment 583 Goodwill 22,537 Core deposit and other intangibles 2,122 Other assets 2,595 Total assets acquired 335,020 LIABILITIES Deposits 273,701 Borrowings 5,000 Other liabilities 287 Total liabilities assumed 278,988 Purchase price $ 56,032 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. Restricted Stock The fair value of restricted stock approximate the respective carrying amount. The stock is comprised of $880 thousand of FHLBB stock and $1.0 million of FRB stock. Loans The loans acquired were recorded at fair value without a carryover of the allowance for loan losses. There were no credit related issues with the acquired portfolio. For the loan purchase accounting, management used the following assumptions: no specific credit mark valuations as determined by the Company's Credit Risk Management, segregation of portfolio into certain loan categories, loan level valuations versus a pooled approach, prepayment rate assumptions and market discount rates. The Company recorded a $1.6 million discount from the results of the loan accounting valuation. There was $133 thousand and $445 thousand of accretion recorded during the three and twelve months ended December 31, 2018 . Deposits - Core Deposit Intangible ("CDI") Accounts included in the CDI include demand deposits, NOW accounts, money market accounts and savings accounts. The fair value of the CDI was derived from using the following assumptions: account retention rates, alternative cost of funds, effective cost of funds, cost savings, present value of annual net cost savings and market discount rate. The Company recorded a $2.1 million CDI from the results of the deposit valuation. There was $123 thousand and $410 thousand of amortization recorded during the three and twelve months ended December 31, 2018 . Certificates of Deposits The certificates of deposits were recorded at fair value. The determination of the fair value was calculated using a discounted cash flow analysis, which involved present valuing the contractual payments over the remaining life of the certificate of deposit at market based-rates. The Company recorded a $1.2 million premium from the results of the certificate of deposit valuation. There was $245 thousand and $817 thousand of amortization recorded during the three and twelve months ended December 31, 2018 . Borrowings The borrowings at acquisition typically require a fair market valuation performed as of the acquisition date. The difference between the current recorded balance and the fair market value will be reflected as a fair value mark. The Company’s Treasury team performed two valuations to review the fair value mark. After reviewing the results, the fair value mark was immaterial and management decided not to record any fair market value adjustment on the acquired borrowings.

Cash, Cash Equivalents and Shor

Cash, Cash Equivalents and Short-Term Investments	12 Months Ended
	Dec. 31, 2018
Cash and Cash Equivalents [Abstract]
Cash, Cash Equivalents and Short-Term Investments	Cash, Cash Equivalents and Short-Term Investments The Banks are required to maintain average reserve balances with the FRB based upon a percentage of certain of the Banks' deposits. As of December 31, 2018 and 2017 , the average amount required to be held before a credit for vault cash was $8.2 million and $5.9 million , respectively. Aggregate reserve balances included in cash and cash equivalents were $48.0 million and $40 million , respectively, as of December 31, 2018 and 2017 . Short-term investments are summarized as follows: At December 31, 2018 2017 (In Thousands) FRB interest bearing reserve $ 34,914 $ 28,263 FHLB overnight deposits 4,628 4,676 Federal funds sold 2,500 2,444 Total short-term investments $ 42,042 $ 35,383 Short-term investments are stated at cost which approximates market value.

Investment Securities

Investment Securities	12 Months Ended
	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Investment Securities	Investment Securities The following tables set forth investment securities available-for-sale, held-to-maturity and equity securities held-for-trading at the dates indicated: At December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value (In Thousands) Investment securities available-for-sale: Debt securities: GSE debentures $ 184,072 $ 99 $ 3,092 $ 181,079 GSE CMOs 107,363 17 4,250 103,130 GSE MBSs 169,334 124 4,369 165,089 SBA commercial loan asset-backed securities 51 — — 51 Corporate debt obligations 40,618 — 910 39,708 U.S. treasury bonds 13,812 65 141 13,736 Total investment securities available-for-sale $ 515,250 $ 305 $ 12,762 $ 502,793 Investment securities held-to-maturity: GSE debentures $ 50,546 $ 22 $ 967 $ 49,601 GSEs MBSs 11,426 — 295 11,131 Municipal obligations 52,304 10 716 51,598 Foreign government obligations 500 — — 500 Total investment securities held-to-maturity $ 114,776 $ 32 $ 1,978 $ 112,830 Equity securities held-for-trading $ 4,207 $ — $ — $ 4,207 At December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value (In Thousands) Investment securities available-for-sale: Debt securities: GSE debentures $ 151,483 $ 70 $ 1,629 $ 149,924 GSE CMOs 131,082 27 4,087 127,022 GSE MBSs 191,281 354 2,322 189,313 SBA commercial loan asset-backed securities 73 — 1 72 Corporate debt obligations 62,811 110 238 62,683 U.S. treasury bonds 8,785 7 62 8,730 Trust preferred securities 1,471 — 73 1,398 Total debt securities 546,986 568 8,412 539,142 Marketable equity securities 978 13 9 982 Total investment securities available-for-sale $ 547,964 $ 581 $ 8,421 $ 540,124 Investment securities held-to-maturity: GSE debentures $ 41,612 $ — $ 811 $ 40,801 GSEs MBSs 13,923 — 218 13,705 Municipal obligations 53,695 159 337 53,517 Foreign government obligations 500 — — 500 Total investment securities held-to-maturity $ 109,730 $ 159 $ 1,366 $ 108,523 As of December 31, 2018 , the fair value of all investment securities available-for-sale was $502.8 million , with net unrealized losses of $12.5 million , compared to a fair value of $540.1 million and net unrealized losses of $7.8 million as of December 31, 2017 . As of December 31, 2018 , $466.7 million , or 92.8% of the portfolio, had gross unrealized losses of $12.8 million , compared to $ 469.2 million , or 86.9% of the portfolio, with gross unrealized losses of $8.4 million as of December 31, 2017 . As of December 31, 2018 , the fair value of all investment securities held-to-maturity was $112.8 million , with net unrealized losses of $1.9 million , compared to a fair value of $108.5 million with net unrealized losses of $1.2 million as of December 31, 2017 . As of December 31, 2018 , $102.1 million , or 90.5% of the portfolio, had gross unrealized losses of $2.0 million . As of December 31, 2017 , $92.9 million , or 85.6% of the portfolio had gross unrealized losses of $1.4 million . As of December 31, 2018 , the Company reported a fair value of $4.2 million of equity securities held-for-trading. The Company did no t have any equity securities held-for-trading as of December 31, 2017 . Investment Securities as Collateral As of December 31, 2018 and 2017 , respectively, $442.5 million and $431.2 million of investment securities were pledged as collateral for repurchase agreements; municipal deposits; treasury, tax and loan deposits (TT&L); swap agreements; and FHLBB borrowings. The Banks did not have any outstanding FRB borrowings as of December 31, 2018 and 2017 . Other-Than-Temporary Impairment ("OTTI") Investment securities as of December 31, 2018 and 2017 that have been in a continuous unrealized loss position for less than twelve months or twelve months or longer are as follows: At December 31, 2018 Less than Twelve Months Twelve Months or Longer Total Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses (In Thousands) Investment securities available-for-sale: GSE debentures $ 25,780 $ 191 $ 130,284 $ 2,901 $ 156,064 $ 3,092 GSE CMOs — — 102,630 4,250 102,630 4,250 GSE MBSs 21,487 113 138,051 4,256 159,538 4,369 SBA commercial loan asset-backed securities — — 51 — 51 — Corporate debt obligations 10,019 93 29,689 817 39,708 910 U.S. Treasury bonds 3,927 37 4,753 104 8,680 141 Temporarily impaired investment securities available-for-sale 61,213 434 405,458 12,328 466,671 12,762 Investment securities held-to-maturity: GSE debentures — — 40,653 967 40,653 967 GSEs MBSs — — 11,080 295 11,080 295 Municipal obligations 14,813 107 35,058 609 49,871 716 Foreign government obligations — — 500 — 500 — Temporarily impaired investment securities held-to-maturity 14,813 107 87,291 1,871 102,104 1,978 Total temporarily impaired investment securities $ 76,026 $ 541 $ 492,749 $ 14,199 $ 568,775 $ 14,740 At December 31, 2017 Less than Twelve Months Twelve Months or Longer Total Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses (In Thousands) Investment securities available-for-sale: GSE debentures $ 120,409 $ 1,263 $ 12,481 $ 366 $ 132,890 $ 1,629 GSE CMOs 2,862 34 123,548 4,053 126,410 4,087 GSE MBSs 94,985 753 74,782 1,569 169,767 2,322 SBA commercial loan asset-backed securities 34 — 33 1 67 1 Corporate debt obligations 30,978 154 2,423 84 33,401 238 U.S. Treasury bonds 4,767 62 — — 4,767 62 Trust preferred securities — — 1,398 73 1,398 73 Marketable equity securities — — 503 9 503 9 Temporarily impaired investment securities available-for-sale 254,035 2,266 215,168 6,155 469,203 8,421 Investment securities held-to-maturity: GSE debentures 26,594 281 14,208 530 40,802 811 GSEs MBSs 1,996 15 11,674 203 13,670 218 Municipal obligations 30,542 235 7,408 102 37,950 337 Foreign government obligations — — 500 — 500 — Temporarily impaired investment securities held-to-maturity 59,132 531 33,790 835 92,922 1,366 Total temporarily impaired investment securities $ 313,167 $ 2,797 $ 248,958 $ 6,990 $ 562,125 $ 9,787 The Company performs regular analysis on the investment securities available-for-sale portfolio to determine whether a decline in fair value indicates that an investment security is OTTI. In making these OTTI determinations, management considers, among other factors, the length of time and extent to which the fair value has been less than amortized cost; projected future cash flows; credit subordination and the creditworthiness; capital adequacy and near-term prospects of the issuers. Management also considers the Company's capital adequacy, interest-rate risk, liquidity and business plans in assessing whether it is more likely than not that the Company will sell or be required to sell the investment securities before recovery. If the Company determines that a decline in fair value is OTTI and that it is more likely than not that the Company will not sell or be required to sell the investment security before recovery of its amortized cost, the credit portion of the impairment loss is recognized in the Company's consolidated statement of income and the noncredit portion is recognized in accumulated other comprehensive income. The credit portion of the OTTI impairment represents the difference between the amortized cost and the present value of the expected future cash flows of the investment security. If the Company determines that a decline in fair value is OTTI and it is more likely than not that it will sell or be required to sell the investment security before recovery of its amortized cost, the entire difference between the amortized cost and the fair value of the security will be recognized in the Company's consolidated statement of income. Investment Securities Available-For-Sale Impairment Analysis The following discussion summarizes, by investment security type, the basis for evaluating if the applicable investment securities within the Company’s available-for-sale portfolio were OTTI as of December 31, 2018 . Based on the analysis below and the determination that, it is more likely than not that the Company will not sell or be required to sell the investment securities before recovery of its amortized cost. The Company's ability and intent to hold these investment securities until recovery is supported by the Company's strong capital and liquidity positions as well as its historically low portfolio turnover. As such, management has determined that the investment securities are not OTTI as of December 31, 2018 . If market conditions for investment securities worsen or the creditworthiness of the underlying issuers deteriorates, it is possible that the Company may recognize additional OTTI in future periods. U.S. Government-Sponsored Enterprises The Company invests in securities issued by U.S. Government-sponsored enterprises ("GSEs"), including GSE debentures, mortgage-backed securities ("MBSs"), and collateralized mortgage obligations ("CMOs"). GSE securities include obligations issued by the Federal National Mortgage Association ("FNMA"), the Federal Home Loan Mortgage Corporation ("FHLMC"), the Government National Mortgage Association ("GNMA"), the Federal Home Loan Banks ("FHLB") and the Federal Farm Credit Bank. As of December 31, 2018 , only GNMA MBSs and CMOs, and Small Business Administration ("SBA") commercial loan asset-backed securities in our available-for-sale portfolio with an estimated fair value of $20.6 million were backed explicitly by the full faith and credit of the U.S. Government, compared to $23.7 million as of December 31, 2017 . As of December 31, 2018 , the Company owned 60 GSE debentures with a total fair value of $181.1 million , and a net unrealized loss of $3.0 million . As of December 31, 2017 , the Company held 48 GSE debentures with a total fair value of $149.9 million , and a net unrealized loss of $1.6 million . As of December 31, 2018 , 51 of the 60 securities in this portfolio were in an unrealized loss position. As of December 31, 2017 , 43 of the 48 securities in this portfolio were in an unrealized loss position. All securities are performing and backed by the implicit (FHLB/FNMA/FHLMC) or explicit (GNMA/SBA) guarantee of the U.S Government. For the years ended December 31, 2018 and 2017 , the Company purchased a total of $33.9 million and $54.2 million , respectively, of GSE debentures. As of December 31, 2018 , the Company owned 61 GSE CMOs with a total fair value of $103.1 million and a net unrealized loss of $4.2 million . As of December 31, 2017 , the Company held 62 GSE CMOs with a total fair value of $127.0 million with a net unrealized loss of $4.1 million . As of December 31, 2018 , 46 of the 61 securities in this portfolio were in an unrealized loss position. As of December 31, 2017 , 47 of the 62 securities in this portfolio were in an unrealized loss position. All securities are performing and backed by the implicit (FHLB/FNMA/FHLMC) or explicit (GNMA) guarantee of the U.S Government. For the year ended December 31, 2018 and 2017 , the Company did no t purchase any GSE CMOs. As of December 31, 2018 , the Company owned 165 GSE MBSs with a total fair value of $165.1 million and a net unrealized loss of $4.2 million . As of December 31, 2017 , the Company held 194 GSE MBSs with a total fair value of $189.3 million with a net unrealized loss of $2.0 million . As of December 31, 2018 , 93 of the 165 securities in this portfolio were in an unrealized loss position. As of December 31, 2017 , 82 of the 194 securities in this portfolio were in an unrealized loss position. All securities are performing and backed by the implicit (FHLB/FNMA/FHLMC) or explicit (GNMA) guarantee of the U.S Government. For the years ended December 31, 2018 and 2017 , the Company purchased a total of $15.2 million and $18.3 million , respectively, of GSE MBSs. SBA Commercial Loan Asset-Backed As of December 31, 2018 , the Company owned four SBA securities with a total fair value of $0.1 million , which approximated amortized cost. As of December 31, 2017 , the Company owned five SBA securities with a total fair value of $0.1 million which approximated amortized cost. As of December 31, 2018 , four of the four securities in this portfolio were in an unrealized loss position. As of December 31, 2017 , four of the five securities in this portfolio were in an unrealized loss position. All securities are performing and backed by the explicit (SBA) guarantee of the U.S Government. Corporate Obligations From time to time, the Company may invest in high-quality corporate obligations to provide portfolio diversification and improve the overall yield on the portfolio. As of December 31, 2018 , the Company owned 11 corporate obligation securities with a total fair value of $39.7 million and a net unrealized loss of $0.9 million . This compares to 19 corporate obligation securities with a total fair value of $62.7 million and a net unrealized loss of $0.1 million as of December 31, 2017 . As of December 31, 2018 , 11 of the 11 securities in this portfolio were in an unrealized loss position. As of December 31, 2017 , nine of the nineteen securities in this portfolio were in an unrealized loss position. Full collection of the obligations is expected because the financial condition of the issuers is sound, they have not defaulted on scheduled payments, the obligations are rated investment grade, and the Company has the ability and intent to hold the obligations for a period of time to recover the amortized cost. For the year ended December 31, 2018 , the Company did no t purchase any corporate obligations as compared to 2017 , when the Company purchased $14.5 million of corporate obligations. U.S. Treasury Bonds The Company invests in securities issued by the U.S. government. As of December 31, 2018 , the Company owned seven U.S. Treasury bonds with a total fair value of $13.7 million and a net unrealized loss of $0.1 million . As of December 31, 2017 , the Company owned two U.S. Treasury bonds with a total fair value of $8.7 million and a net unrealized loss of $0.1 million . As of December 31, 2018 , two of the seven securities in this portfolio were in an unrealized loss position. As of December 31, 2017 , all of the securities in this portfolio were in unrealized loss positions. For the years ended December 31, 2018 and 2017 , the Company purchased $24.7 million and $4.0 million in U.S. Treasury bonds, respectively. Trust Preferred Securities Trust preferred securities represent subordinated debt issued by financial institutions. As of December 31, 2018 , the Company did not own trust preferred securities. This compares to two trust preferred securities with a total fair value of $1.4 million and a net unrealized loss of $0.1 million as of December 31, 2017 . As of December 31, 2017 , both of the securities in this portfolio were in an unrealized loss position. Equity Securities Held-for-Trading As of December 31, 2017 , the Company had two marketable equity securities classified as available-for-sale with a fair value of $1.0 million . During the third quarter of 2018, the Company re-designated all equity securities as held-for-trading. As of December 31, 2018 , the Company owned three equity securities held-for-trading with a fair value of $4.2 million . Held-for-trading securities are recorded on a mark-to-market basis with realized gains and losses recognized through the income statement. Investment Securities Held-to-Maturity Impairment Analysis The following discussion summarizes by investment security type, the basis for evaluating if the applicable investment securities within the Company's held-to-maturity portfolio were OTTI at December 31, 2018 . Management does not intend to sell these securities prior to maturity. U.S. Government-Sponsored Enterprises As of December 31, 2018 , the Company owned 17 GSE debentures with a total fair value of $49.6 million and a net unrealized loss of $0.9 million . As of December 31, 2017 , the Company owned 14 GSE debentures with a total fair value of $40.8 million and a net unrealized loss of $0.8 million . As of December 31, 2018 , 14 of the 17 securities in this portfolio were in an unrealized loss position. At December 31, 2017 , all securities in this portfolio were in an unrealized loss position. All securities are performing and backed by the implicit (FHLB/FNMA/FHLMC) or explicit (GNMA) guarantee of the U.S Government. During the years ended December 31, 2018 and December 31, 2017 , the Company purchased a total of $8.9 million and $26.9 million in GSE debentures, respectively. As of December 31, 2018 , the Company owned 11 GSE MBSs with a total fair value of $11.1 million and a net unrealized loss of $0.3 million . As of December 31, 2017 , the Company owned 11 GSE MBSs with a total fair value of $13.7 million and an unrealized loss of $0.2 million . As of December 31, 2018 , eight of the eleven securities in this portfolio were in an unrealized loss position. At December 31, 2017 , eight of the eleven securities were in an unrealized loss position. All securities are performing and backed by the implicit (FHLB/FNMA/FHLMC) or explicit (GNMA) guarantee of the U.S Government. During the year ended December 31, 2018 and 2017 , the Company did no t purchase any GSE MBSs. Municipal Obligations As of December 31, 2018 , the Company owned 98 municipal obligation securities with a total fair value and total amortized cost of $51.6 million and $52.3 million , respectively. As of December 31, 2017 , the Company owned 100 municipal obligation securities with a total fair value and total amortized cost of $53.5 million and $53.7 million , respectively. As of December 31, 2018 , 94 of the 98 securities in this portfolio were in an unrealized loss position as compared to December 31, 2017 , when 69 of the 100 securities were in an unrealized loss position. During the year ended December 31, 2018 and 2017 , the Company did no t purchase any of municipal obligations. Foreign Government Obligations As of December 31, 2018 , the Company owned one foreign government obligation security with a fair value and amortized cost of $0.5 million . As of December 31, 2017 , the Company owned one foreign government obligation security with a fair value and amortized cost of $0.5 million . As of December 31, 2018 and 2017 , the security was in an unrealized loss position. During the year ended December 31, 2018 and 2017 , the Company did no t purchase any foreign government obligation securities. Portfolio Maturities The final stated maturities of the debt securities are as follows for the periods indicated: At December 31, 2018 2017 Amortized Cost Estimated Fair Value Weighted Average Rate Amortized Cost Estimated Fair Value Weighted Average Rate (Dollars in Thousands) Investment securities available-for-sale: Within 1 year $ 12,041 $ 12,007 2.03% $ 23,612 $ 23,652 2.27% After 1 year through 5 years 195,701 192,692 2.14% 142,772 142,029 2.05% After 5 years through 10 years 115,665 112,819 2.18% 136,746 134,978 2.06% Over 10 years 191,843 185,275 2.17% 243,856 238,483 2.06% $ 515,250 $ 502,793 2.16% $ 546,986 $ 539,142 2.07% Investment securities held-to-maturity: Within 1 year $ 7,640 $ 7,618 1.17% $ 918 $ 916 0.78% After 1 year through 5 years 72,735 71,492 1.84% 58,335 57,939 1.74% After 5 years through 10 years 23,025 22,640 2.20% 36,589 35,998 1.79% Over 10 years 11,376 11,080 2.13% 13,888 13,670 1.98% $ 114,776 $ 112,830 1.89% $ 109,730 $ 108,523 1.78% Actual maturities of debt securities will differ from those presented above since certain obligations amortize and may also provide the issuer the right to call or prepay the obligation prior to scheduled maturity without penalty. MBSs and CMOs are included above based on their final stated maturities; the actual maturities, however, may occur earlier due to anticipated prepayments and stated amortization of cash flows. As of December 31, 2018 , issuers of debt securities with an estimated fair value of $19.1 million had the right to call or prepay the obligations. Of the $19.1 million , approximately $8.4 million matures in 1 - 5 years, $10.7 million matures in 6 - 10 years, and none mature after ten years. As of December 31, 2017 , issuers of debt securities with an estimated fair value of approximately $58.8 million had the right to call or prepay the obligations. Of the $58.8 million , $32.7 million matures in 1-5 years, $25.2 million matures in 6-10 years, and $0.9 million matures after ten years. Security Sales Security transactions are recorded on the trade date. When securities are sold, the adjusted cost of the specific security sold is used to compute the gain or loss on the sale. On February 3, 2017, the Company, through BSC, received $319.04 in cash and 14.876 shares of Community Bank Systems, Inc. (“CBU”) common stock in exchange for each of the 9,721 shares of Northeast Retirement Services, Inc. (“NRS”) stock held by BSC. The exchange was completed in accordance with the merger agreement entered into between NRS and CBU. As part of the merger agreement, the Company was restricted to selling 5,071 shares of CBU per day in the open market. During the quarter ended March 31, 2017, the Company completed the sale of all of the CBU shares acquired in the merger. When securities are sold, the adjusted cost of the specific security sold is used to compute the gain or loss on the sale. The table below includes the activity with respect to the sale of the CBU shares. On March 6, 2018, the Company, through its wholly owned subsidiary, BSC, received $0.6 million in cash and 11,303 shares of CBU common stock as settlement for the indemnification escrow on the 12 month anniversary date of the merger between NRS and CBU. The Company subsequently sold all 11,303 shares of the CBU stock and recognized a gain on the sale of $0.6 million . On July 26, 2017, the Savings Bank Life Insurance Company of Massachusetts ("SBLI") converted from a Massachusetts stock insurance company to a Massachusetts mutual insurance company and, as a result, the Company, through its wholly owned subsidiary, Brookline Securities received $500 for the one share of Class A Common Stock and $128 per share for its 2,070 shares of Class B Common Stock held of SBLI, in exchange for $265.5 thousand in cash. Brookline Securities recognized a nominal gain on the exchange for the year end December 31, 2017. During the month of March 2018, the Company, through Brookline Bank’s wholly owned subsidiary, LSC, sold three trust preferred securities with a book value of $1.5 million for a loss of $0.1 million . The table below includes the activity with respect to the sale of the trust preferred securities and restricted equity securities. Sales of investment and restricted equity securities are summarized as follows: Year Ended December 31, 2018 2017 (In Thousands) Proceeds from sales of debt securities $ 20,000 $ — Proceeds from sales of marketable and restricted equity securities 2,700 11,393 Gross gains from sales 1,472 $ 11,612 Gross losses from sales (68 ) (219 ) Gain on sales of securities, net $ 1,404 $ 11,393 There were no sales of investment and restricted equity securities in 2016 .

Restricted Equity Securities

Restricted Equity Securities	12 Months Ended
	Dec. 31, 2018
Restricted Investments Note [Abstract]
Restricted Equity Securities	Restricted Equity Securities Investments in the restricted equity securities of various entities are as follows: At December 31, 2018 2017 (In Thousands) FHLBB stock $ 43,655 $ 42,427 FRB stock 17,995 16,842 Other restricted equity securities 101 100 $ 61,751 $ 59,369 The Company invests in the stock of FHLBB as one of the requirements to borrow. As of December 31, 2018 and 2017 , FHLBB stock is recorded at its carrying value, which is equal to cost and which management believes approximates its fair value. The FHLBB stated that it remained in compliance with all regulatory capital ratios as of December 31, 2018 and was classified as "adequately capitalized" by its regulator, based on the FHLBB's financial information as of September 30, 2018. The FHLBB paid a dividend to member banks at an annualized rate of 414 basis points in 2017. The FHLBB increased its dividend from 499 basis points in the first quarter of 2018 to 587 basis points in the fourth quarter of 2018 . As of December 31, 2018 , the Company's investment in FHLBB stock exceeded its required investment which provides for additional borrowing capacity. The Company invests in the stock of the Federal Reserve Bank of Boston as required by its the Banks' membership in the Federal Reserve system. As of December 31, 2018 and 2017 , Federal Reserve Bank of Boston stock is recorded at its carrying value, which is equal to cost and which management believes approximates its fair value. The Company, through its wholly owned subsidiary, BSC held 9,721 shares of restricted equity securities of NRS. This investment was recorded at cost of $122 thousand as no readily determinable fair value was available. On December 5, 2016, CBU announced entry into a merger agreement to acquire NRS. After receiving stockholder and regulatory approvals, CBU completed the acquisition of NRS on February 3, 2017. The Company exchanged the 9,721 shares of NRS and received $319.04 in cash and 14.876 shares of CBU common stock for each share of NRS held. As part of the merger agreement, the Company was restricted to selling 5,071 shares per day in the open market. The Company completed the sale of all CBU shares during the first quarter of 2017. The Company recognized a gain on the sale of securities of $11.4 million for the quarter ending March 31, 2017. Brookline Securities held one Class A Common Stock share and 2,070 Class B Common Stock shares of the Savings Bank Life Insurance Company of Massachusetts ("SBLI"). In July 2017, SBLI converted from a Massachusetts stock insurance company to a Massachusetts mutual insurance company and, as a result, Brookline Securities received $500 for one share of Class A Common Stock and $128 per share for its 2,070 shares of Class B Common Stock of SBLI, in exchange for $265.5 thousand in cash. Brookline Securities recognized a nominal gain on the exchange.

Loans and Leases

Loans and Leases	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Loans and Leases	Loans and Leases The following tables present loan and lease balances and weighted average coupon rates for the originated and acquired loan and lease portfolios at the dates indicated: At December 31, 2018 Originated Acquired Total Balance Weighted Average Coupon Balance Weighted Average Coupon Balance Weighted Average Coupon (Dollars In Thousands) Commercial real estate loans: Commercial real estate $ 2,208,904 4.61 % $ 121,821 4.62 % $ 2,330,725 4.61 % Multi-family mortgage 799,813 4.51 % 47,898 4.58 % 847,711 4.51 % Construction 151,138 5.62 % 22,162 6.74 % 173,300 5.76 % Total commercial real estate loans 3,159,855 4.63 % 191,881 4.85 % 3,351,736 4.64 % Commercial loans and leases: Commercial 712,630 4.96 % 23,788 5.39 % 736,418 4.97 % Equipment financing 978,840 7.61 % 3,249 5.97 % 982,089 7.60 % Condominium association 50,451 4.70 % — — % 50,451 4.70 % Total commercial loans and leases 1,741,921 6.44 % 27,037 5.46 % 1,768,958 6.43 % Consumer loans: Residential mortgage 653,059 4.09 % 129,909 4.45 % 782,968 4.15 % Home equity 331,014 5.05 % 45,470 5.39 % 376,484 5.09 % Other consumer 23,260 5.55 % 110 17.81 % 23,370 5.61 % Total consumer loans 1,007,333 4.44 % 175,489 4.70 % 1,182,822 4.48 % Total loans and leases $ 5,909,109 5.13 % $ 394,407 4.83 % $ 6,303,516 5.11 % At December 31, 2017 Originated Acquired Total Balance Weighted Average Coupon Balance Weighted Average Coupon Balance Weighted Average Coupon (Dollars In Thousands) Commercial real estate loans: Commercial real estate $ 2,069,392 4.17 % $ 105,577 4.37 % $ 2,174,969 4.18 % Multi-family mortgage 735,921 4.09 % 24,749 4.48 % 760,670 4.10 % Construction 140,138 4.58 % — — % 140,138 4.58 % Total commercial real estate loans 2,945,451 4.17 % 130,326 4.39 % 3,075,777 4.18 % Commercial loans and leases: Commercial 696,825 4.35 % 8,179 5.77 % 705,004 4.37 % Equipment financing 861,974 7.28 % 4,514 5.92 % 866,488 7.27 % Condominium association 52,619 4.49 % — — % 52,619 4.49 % Total commercial loans and leases 1,611,418 5.92 % 12,693 5.82 % 1,624,111 5.92 % Consumer loans: Residential mortgage 604,897 3.81 % 55,168 4.28 % 660,065 3.85 % Home equity 314,189 4.16 % 41,765 4.62 % 355,954 4.21 % Other consumer 14,667 5.51 % 105 18.00 % 14,772 5.60 % Total consumer loans 933,753 3.95 % 97,038 4.44 % 1,030,791 4.00 % Total loans and leases $ 5,490,622 4.65 % $ 240,057 4.49 % $ 5,730,679 4.64 % The net unamortized deferred loan origination fees and costs included in total loans and leases were $15.6 million and $15.5 million as of December 31, 2018 and 2017 , respectively. The Company's Banks and subsidiaries lend primarily in eastern Massachusetts, southern New Hampshire and Rhode Island, with the exception of equipment financing, 26.8% of which is in the greater New York and New Jersey metropolitan area and 73.2% of which is in other areas in the United States of America as of December 31, 2018 , as compared to 28.0% of which is in the greater New York and New Jersey metropolitan area and 72.0% of which is in other areas in the United States of America as of December 31, 2017 . Accretable Yield for the Acquired Loan Portfolio The following table summarizes activity in the accretable yield for the acquired loan portfolio for the periods indicated: Year Ended December 31, 2018 2017 2016 (In Thousands) Balance at beginning of year $ 10,522 $ 14,353 $ 20,796 Accretion (4,117 ) (7,801 ) (6,781 ) Reclassification from nonaccretable difference as a result from changes in expected cash flows 1,500 3,970 338 Balance at end of year $ 7,905 $ 10,522 $ 14,353 On a quarterly basis, subsequent to acquisition, management reforecasts the expected cash flows for acquired ASC 310-30 loans, taking into account prepayment speeds, probability of default and loss given defaults. Management compares cash flow projections per the reforecast to the original cash flow projections and determines whether any reduction in cash flow expectations are due to deterioration, or if the change in cash flow expectation is related to noncredit events. This cash flow analysis is used to evaluate the need for a provision for loan and lease losses and/or prospective yield adjustments. During the years ended December 31, 2018 , 2017 and 2016 , accretable yield adjustments totaling $1.5 million , $4.0 million , and $0.3 million , respectively, were made for certain loan pools. These accretable yield adjustments, which are subject to continued re-assessment, will be recognized over the remaining lives of those pools. Related Party Loans The Banks' authority to extend credit to their respective directors and executive officers, as well as to entities controlled by such persons, is currently governed by the requirements of the Sarbanes-Oxley Act and Regulation O of the FRB. Among other things, these provisions require that extensions of credit to insiders (1) be made on terms that are substantially the same as, and follow credit underwriting procedures that are not less stringent than, those prevailing for comparable transactions with unaffiliated persons and that do not involve more than the normal risk of repayment or present other unfavorable features; and (2) not exceed certain limitations on the amount of credit extended to such persons, individually and in the aggregate, which limits are based, in part, on the amount of the Banks' capital. In addition, the extensions of credit to insiders must be approved by the applicable Bank's Board of Directors. The following table summarizes the change in the total amounts of loans and advances, to directors, executive officers and their affiliates for the periods indicated. All loans were performing as of December 31, 2018 . Year Ended December 31, 2018 2017 (In Thousands) Balance at beginning of year $ 47,941 $ 43,458 New loans granted during the year 2,842 13,554 Advances on lines of credit 193 473 Repayments (4,205 ) (9,544 ) Balance at end of year $ 46,771 $ 47,941 Unfunded commitments on extensions of credit to related parties totaled $5.9 million and $15.7 million as of December 31, 2018 and 2017 , respectively. Loans and Leases Pledged as Collateral As of December 31, 2018 and 2017 , there were $3.0 billion and $2.3 billion , respectively, of loans and leases pledged as collateral for repurchase agreements; municipal deposits; treasury, tax and loan deposits; swap agreements; and FHLBB borrowings. The Banks did not have any outstanding FRB borrowings as of December 31, 2018 and 2017 .

Allowance for Loan and Lease Lo

Allowance for Loan and Lease Losses	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Allowance for Loan and Lease Losses	Allowance for Loan and Lease Losses The following tables present the changes in the allowance for loan and lease losses and the recorded investment in loans and leases by portfolio segment for the periods indicated: Year Ended December 31, 2018 Commercial Real Estate Commercial Consumer Total (In Thousands) Balance at December 31, 2017 $ 27,112 $ 26,333 $ 5,147 $ 58,592 Charge-offs (103 ) (6,585 ) (540 ) (7,228 ) Recoveries — 2,287 290 2,577 Provision for loan and lease losses 1,178 3,248 325 4,751 Balance at December 31, 2018 $ 28,187 $ 25,283 $ 5,222 $ 58,692 Year Ended December 31, 2017 Commercial Real Estate Commercial Consumer Total (In Thousands) Balance at December 31, 2016 $ 27,645 $ 20,906 $ 5,115 $ 53,666 Charge-offs (494 ) (14,914 ) (403 ) (15,811 ) Recoveries 476 1,158 319 1,953 (Credit) provision for loan and lease losses (515 ) 19,183 116 18,784 Balance at December 31, 2017 $ 27,112 $ 26,333 $ 5,147 $ 58,592 Year Ended December 31, 2016 Commercial Real Estate Commercial Consumer Total (In Thousands) Balance at December 31, 2015 $ 30,151 $ 22,018 $ 4,570 $ 56,739 Charge-offs (2,169 ) (10,516 ) (1,982 ) (14,667 ) Recoveries — 642 750 1,392 Provision (credit) for loan and lease losses (337 ) 8,762 1,777 10,202 Balance at December 31, 2016 $ 27,645 $ 20,906 $ 5,115 $ 53,666 The liability for unfunded credit commitments, which is included in other liabilities, was $1.9 million , and $1.7 million , at December 31, 2018 , and 2017 , respectively. The changes in the liability for unfunded credit commitments reflect changes in the estimate of loss exposure associated with certain unfunded credit commitments. No credit commitments were charged off against the liability account in the years ended December 31, 2018 , and 2017 . Provision for Credit Losses The provisions for credit losses are set forth below for the periods indicated: Originated Acquired Total Year Ended December 31, Year Ended December 31, Year Ended December 31, 2018 2017 2016 2018 2017 2016 2018 2017 2016 (In Thousands) Provision (credit) for loan and lease losses: Commercial real estate $ 254 $ (343 ) $ (750 ) $ 924 $ (172 ) $ 413 $ 1,178 $ (515 ) $ (337 ) Commercial 3,699 18,899 8,469 (451 ) 284 293 3,248 19,183 8,762 Consumer 556 273 1,263 (231 ) (157 ) 514 325 116 1,777 Total provision for loan and lease losses 4,509 18,829 8,982 242 (45 ) 1,220 4,751 18,784 10,202 Unfunded credit commitments 200 204 151 — — — 200 204 151 Total provision (credit) for credit losses $ 4,709 $ 19,033 $ 9,133 $ 242 $ (45 ) $ 1,220 $ 4,951 $ 18,988 $ 10,353 Allowance for Loan and Lease Losses Methodology Management has established a methodology to determine the adequacy of the allowance for loan and lease losses that assesses the risks and losses inherent in the loan and lease portfolio. Additions to the allowance for loan and lease losses are made by charges to the provision for credit losses. Losses on loans and leases are charged off against the allowance when all or a portion of a loan or lease is considered uncollectible. Subsequent recoveries on loans previously charged off, if any, are credited to the allowance when realized. Management uses a consistent and systematic process and methodology to evaluate the adequacy of the allowance for loan and lease losses on a quarterly basis. For purposes of determining the allowance for loan and lease losses, the Company has segmented certain loans and leases in the portfolio by product type into the following segments: (1) commercial real estate loans, (2) commercial loans and leases, (3) consumer loans. Portfolio segments are further disaggregated into classes based on the associated risks within the segments. Commercial real estate loans are divided into three classes: commercial real estate loans, multi-family mortgage loans, and construction loans. Commercial loans and leases are divided into three classes: commercial loans which includes taxi medallion loans, equipment financing, and loans to condominium associations. Consumer loans are divided into three classes: residential mortgage loans, home equity loans, and other consumer loans. A formula-based credit evaluation approach is applied to each group, coupled with an analysis of certain loans for impairment. For each class of loan, management makes significant judgments in selecting the estimation method that fits the credit characteristics of its class and portfolio segment as set forth below. Also refer to Note 1, "Basis of Presentation," in the consolidated financial statements for more information on the Company's allowance of loan and lease losses methodology. The general allowance related to loans collectively evaluated for impairment is determined using a formula-based approach utilizing the risk ratings of individual credits and loss factors derived from historic portfolio loss rates, which include estimates of incurred losses over an estimated loss emergence period (“LEP”). The LEP was generated utilizing a charge-off look-back analysis which studied the time from the first indication of elevated risk of repayment (or other early event indicating a problem) to eventual charge-off to support the LEP considered in the allowance calculation. This reserving methodology established the approximate number of months of LEP that represents incurred losses for each portfolio. In addition to quantitative measures, relevant qualitative factors include, but are not limited to: (1) levels and trends in past due and impaired loans, (2) levels and trends in charge-offs, (3) changes in underwriting standards, policy exceptions, and credit policy, (4) experience of lending management and staff, (5) economic trends, (6) industry conditions, (7) effects of changes in credit concentrations, (8) interest rate environment, and (9) regulatory and other changes. The general allowance related to the acquired loans collectively evaluated for impairment is determined based upon the degree, if any, of deterioration in the pooled loans subsequent to acquisition. The qualitative factors used in the determination are the same as those used for originated loans. During the third quarter of 2015, the Company enhanced and refined its general allowance methodology to provide further quantification of probable losses in the portfolio. Under the enhanced methodology, management combined the historical loss histories of the Banks to generate a single set of ratios. Management believes it is appropriate to aggregate the ratios as the Banks share common environmental factors, operate in similar geographic markets, and utilize common underwriting standards in accordance with the Company's Credit Policy. In prior periods to the three months ended September 30, 2015, a historical loss history applicable to each Bank was used. Management employed a similar analysis for the consolidation of the qualitative factors as it did for the quantitative factors. Again, management believes the realignment of the existing nine qualitative factors used at each of the Banks into a single group of factors for use across the Company is appropriate based on the commonality of environmental factors, markets and underwriting standards among the Banks. In prior periods to the three months ended September 30, 2015, each of the Banks utilized a set of qualitative factors applicable to each Bank. Based on the refinements to the Company’s allowance methodology discussed above, management determined that the potential risks anticipated by the unallocated allowance are now incorporated into the allowance methodology, making the unallocated allowance unnecessary. In prior periods, the unallocated allowance was used to recognize the estimated risk associated with the allocated general and specific allowances. It incorporated management’s evaluation of existing conditions that were not included in the allocated allowance determinations and provided for losses that arise outside of the ordinary course of business. Specific valuation allowances are established for impaired originated loans with book values greater than the discounted present value of expected future cash flows or, in the case of collateral-dependent impaired loans, for any excess of a loan's book balance and the fair value of its underlying collateral. Specific valuation allowances are established for acquired loans with deterioration in the discounted present value of expected future cash flows since acquisitions or, in the case of collateral dependent impaired loans, for any increase in the excess of a loan's book balance greater than the fair value of its underlying collateral. A specific valuation allowance for losses on TDR loans is initially determined by comparing the net carrying amount of the troubled debt restructured loan with the restructured loan's cash flows discounted at the original effective rate. Impaired loans are reviewed quarterly with adjustments made to the calculated reserve as necessary. As of December 31, 2018 , management believes that the methodology for calculating the allowance provides a reasonable basis for determining and reporting on probable losses in the Company’s loan portfolios. As of December 31, 2018 , the Company had a portfolio of approximately $13.7 million in loans secured by taxi medallions issued by the cities of Boston and Cambridge. As of December 31, 2017 , this portfolio was approximately $19.7 million . Application-based mobile ride services, such as Uber and Lyft, have generated increased competition in the transportation sector, resulting in a reduction in taxi utilization and, as a result, a reduction in the collateral value and credit quality of taxi medallion loans. This has increased the likelihood that loans secured by taxi medallions may default, or that the borrowers may be unable to repay these loans at maturity, resulting in an increase in past due loans, troubled debt restructurings, and charge-offs. Therefore, beginning with the three months ended September 30, 2015, the Company’s allowance calculation included an enhanced segmentation of the commercial loans and leases to reflect the increased risk in the Company’s taxi medallion portfolio. This allowance calculation segmentation represents management’s estimations of the special risks associated with the taxi portfolio. As of December 31, 2018 , the Company had an allowance for loan and lease losses associated with taxi medallion loans of $2.5 million of which $1.9 million were specific reserves and $0.6 million was a general reserve. As of December 31, 2017 , the Company had a reserve for loan and lease losses associated with taxi medallion loans of $3.8 million of which $2.7 million were specific reserves and $1.1 million was a general reserve. The decrease in the allowance for loans associated with taxi medallion loans was primarily driven by the decrease in specific reserves due to the charge-offs to the portfolio. The total troubled debt restructured loans secured by taxi medallions remained consistent at $3.7 million at December 31, 2018 and 2017 . The total loans secured by taxi medallions that were placed on nonaccrual decreased to $3.7 million at December 31, 2018 from $7.8 million at December 31, 2017 . The decrease in total loans secured by taxi medallions was primarily driven by the charge-offs of $3.8 million and the pay down in taxi medallion loans. Further declines in demand for taxi services or further deterioration in the value of taxi medallions may result in higher delinquencies and losses beyond that provided for in the allowance for loan and lease losses. The general allowance for loan and lease losses was $55.6 million as of December 31, 2018 , compared to $55.5 million as of December 31, 2017 . The general portion of the allowance for loan and lease losses increased by $0.1 million during the year ended December 31, 2018 , as a result of the continued growth in the Company's loan portfolios, partly offset by the decrease in historical loss factors applied to the commercial loan portfolio. The specific allowance for loan and lease losses remained consistent at $3.1 million as of December 31, 2018 and 2017 . Credit Quality Assessment At the time of loan origination, a rating is assigned based on the capacity to pay and general financial strength of the borrower, the value of assets pledged as collateral, and the evaluation of third party support such as a guarantor. The Company periodically monitors the quality of the loan portfolio using all available information. The officer responsible for handling each loan is required to initiate changes to risk ratings when changes in facts and circumstances occur that warrant an upgrade or downgrade in a loan rating. Based on this information, loans demonstrating certain payment issues or other weaknesses may be categorized as delinquent, impaired, nonperforming and/or put on nonaccrual status. Additionally, in the course of resolving such loans, the Company may choose to restructure the contractual terms of certain loans to match the borrower's ability to repay the loan based on their current financial condition. If a restructured loan meets certain criteria, it may be categorized as a troubled debt restructuring. The Company reviews numerous credit quality indicators when assessing the risk in its loan portfolio. For all loans, the Company utilizes an eight-grade loan rating system, which assigns a risk rating to each borrower based on a number of quantitative and qualitative factors associated with a loan transaction. Factors considered include industry and market conditions; position within the industry; earnings trends; operating cash flow; asset/liability values; debt capacity; guarantor strength; management and controls; financial reporting; collateral; and other considerations. In addition, the Company's independent loan review group evaluates the credit quality and related risk ratings in all loan portfolios. The results of these reviews are reported to the Risk Committee of the Board of Directors on a periodic basis and annually to the Board of Directors. For the consumer loans, the Company heavily relies on payment status for calibrating credit risk. The ratings categories used for assessing credit risk in the commercial real estate, multi-family mortgage, construction, commercial, equipment financing, condominium association and other consumer loan and lease classes are defined as follows: 1 -4 Rating—Pass Loan rating grades "1" through "4" are classified as "Pass," which indicates borrowers are performing in accordance with the terms of the loan and are less likely to result in loss due to the capacity of the borrower to pay and the adequacy of the value of assets pledged as collateral. 5 Rating—Other Assets Especially Mentioned ("OAEM") Borrowers exhibit potential credit weaknesses or downward trends deserving management's attention. If not checked or corrected, these trends will weaken the Company's asset and position. While potentially weak, currently these borrowers are marginally acceptable; no loss of principal or interest is envisioned. 6 Rating—Substandard Borrowers exhibit well defined weaknesses that jeopardize the orderly liquidation of debt. Substandard loans may be inadequately protected by the current net worth and paying capacity of the obligors or by the collateral pledged, if any. Normal repayment from the borrower is in jeopardy. Although no loss of principal is envisioned, there is a distinct possibility that a partial loss of interest and/or principal will occur if the deficiencies are not corrected. Collateral coverage may be inadequate to cover the principal obligation. 7 Rating—Doubtful Borrowers exhibit well-defined weaknesses that jeopardize the orderly liquidation of debt with the added provision that the weaknesses make collection of the debt in full, on the basis of currently existing facts, conditions, and values, highly questionable and improbable. Serious problems exist to the point where partial loss of principal is likely. 8 Rating—Definite Loss Borrowers deemed incapable of repayment. Loans to such borrowers are considered uncollectible and of such little value that continuation as active assets of the Company is not warranted. Assets rated as "OAEM," "substandard" or "doubtful" based on criteria established under banking regulations are collectively referred to as "criticized" assets. Credit Quality Information The following tables present the recorded investment in loans in each class as of December 31, 2018 by credit quality indicator. At December 31, 2018 Commercial Real Estate Multi- Family Mortgage Construction Commercial Equipment Financing Condominium Association Other Consumer Total (In Thousands) Originated: Loan rating: Pass $ 2,198,377 $ 799,483 $ 150,742 $ 685,773 $ 969,275 $ 50,186 $ 23,249 $ 4,877,085 OAEM 6,096 — — 3,726 52 — — 9,874 Substandard 4,431 330 396 22,870 6,895 265 11 35,198 Doubtful — — — 261 2,618 — — 2,879 Total originated 2,208,904 799,813 151,138 712,630 978,840 50,451 23,260 4,925,036 Acquired: Loan rating: Pass 111,919 47,715 22,162 23,250 3,240 — 110 208,396 OAEM 626 — — 236 — — — 862 Substandard 9,276 183 — 302 9 — — 9,770 Total acquired 121,821 47,898 22,162 23,788 3,249 — 110 219,028 Total loans $ 2,330,725 $ 847,711 $ 173,300 $ 736,418 $ 982,089 $ 50,451 $ 23,370 $ 5,144,064 As of December 31, 2018 , there were no loans categorized as definite loss. At December 31, 2018 Residential Mortgage Home Equity ($ In Thousands) Originated: Loan-to-value ratio: Less than 50% $ 171,523 21.9 % $ 142,534 37.9 % 50% - 69% 287,337 36.7 % 84,423 22.4 % 70% - 79% 173,870 22.2 % 73,898 19.6 % 80% and over 19,030 2.4 % 30,129 8.0 % Data not available* 1,299 0.2 % 30 — % Total originated 653,059 83.4 % 331,014 87.9 % Acquired: Loan-to-value ratio: Less than 50% 36,752 4.6 % 24,705 6.6 % 50%—69% 53,788 6.9 % 10,353 2.7 % 70%—79% 26,510 3.4 % 1,000 0.3 % 80% and over 6,701 0.9 % 4,348 1.2 % Data not available* 6,158 0.8 % 5,064 1.3 % Total acquired 129,909 16.6 % 45,470 12.1 % Total loans $ 782,968 100.0 % $ 376,484 100.0 % _______________________________________________________________________________ * Represents accounts for which data are not available. The following tables present the recorded investment in loans in each class as of December 31, 2017 by credit quality indicator. At December 31, 2017 Commercial Real Estate Multi- Family Mortgage Construction Commercial Equipment Financing Condominium Association Other Consumer Total (In Thousands) Originated: Loan rating: Pass $ 2,054,376 $ 735,313 $ 139,278 $ 670,265 $ 850,006 $ 52,619 $ 14,628 $ 4,516,485 OAEM 8,889 — — 7,691 3,630 — — 20,210 Substandard 5,926 608 860 17,681 5,012 — 39 30,126 Doubtful 201 — — 1,188 3,326 — — 4,715 Total originated 2,069,392 735,921 140,138 696,825 861,974 52,619 14,667 4,571,536 Acquired: Loan rating: Pass 94,244 24,459 — 6,643 4,501 — 104 129,951 OAEM 9,839 — — 265 — — 1 10,105 Substandard 1,494 290 — 1,271 13 — — 3,068 Total acquired 105,577 24,749 — 8,179 4,514 — 105 143,124 Total loans $ 2,174,969 $ 760,670 $ 140,138 $ 705,004 $ 866,488 $ 52,619 $ 14,772 $ 4,714,660 As of December 31, 2017 , there were no loans categorized as definite loss. At December 31, 2017 Residential Mortgage Home Equity ($ In Thousands) Originated: Loan-to-value ratio: Less than 50% $ 153,373 23.2 % $ 148,137 41.6 % 50%—69% 265,328 40.2 % 75,099 21.1 % 70%—79% 168,272 25.5 % 63,742 17.9 % 80% and over 16,547 2.5 % 27,122 7.6 % Data not available* 1,377 0.2 % 89 — % Total originated 604,897 91.6 % 314,189 88.2 % Acquired: Loan-to-value ratio: Less than 50% 16,521 2.5 % 25,312 7.1 % 50%—69% 19,182 2.9 % 13,883 3.9 % 70%—79% 10,507 1.6 % 943 0.3 % 80% and over 7,893 1.2 % 582 0.2 % Data not available* 1,065 0.2 % 1,045 0.3 % Total acquired 55,168 8.4 % 41,765 11.8 % Total loans $ 660,065 100.0 % $ 355,954 100.0 % _______________________________________________________________________________ * Represents accounts for which data are not available. The following table presents information regarding foreclosed residential real estate property for the periods indicated: At December 31, 2018 At December 31, 2017 (In Thousands) Recorded investment in mortgage loans collateralized by residential real estate property that are in the process of foreclosure $ 121 $ 633 Age Analysis of Past Due Loans and Leases The following tables present an age analysis of the recorded investment in total loans and leases as of December 31, 2018 and 2017 . At December 31, 2018 Past Due Loans and Leases Past Due Greater Than 90 Days and Accruing 31-60 Days 61-90 Days Greater Than 90 Days Total Current Total Loans and Leases Nonaccrual Loans and Leases (In Thousands) Originated: Commercial real estate loans: Commercial real estate $ 5,139 $ 896 $ 2,962 $ 8,997 $ 2,199,907 $ 2,208,904 $ 277 $ 3,806 Multi-family mortgage 893 — 145 1,038 798,775 799,813 — 330 Construction 297 — 396 693 150,445 151,138 — 396 Total commercial real estate loans 6,329 896 3,503 10,728 3,149,127 3,159,855 277 4,532 Commercial loans and leases: Commercial 2,021 582 6,244 8,847 703,783 712,630 1,962 6,421 Equipment financing 2,509 650 5,685 8,844 969,996 978,840 12 9,500 Condominium association 320 — — 320 50,131 50,451 — 265 Total commercial loans and leases 4,850 1,232 11,929 18,011 1,723,910 1,741,921 1,974 16,186 Consumer loans: Residential mortgage 400 — 1,597 1,997 651,062 653,059 — 1,842 Home equity 761 25 183 969 330,045 331,014 1 191 Other consumer 51 18 15 84 23,176 23,260 — 17 Total consumer loans 1,212 43 1,795 3,050 1,004,283 1,007,333 1 2,050 Total originated loans and leases $ 12,391 $ 2,171 $ 17,227 $ 31,789 $ 5,877,320 $ 5,909,109 $ 2,252 $ 22,768 (Continued) At December 31, 2018 Past Due Loans and Leases Past Due Greater Than 90 Days and Accruing 31-60 Days 61-90 Days Greater Than 90 Days Total Current Total Loans and Leases Nonaccrual Loans and Leases (In Thousands) Acquired: Commercial real estate loans: Commercial real estate $ — $ 215 $ 9,087 $ 9,302 $ 112,519 $ 121,821 $ 9,018 $ 122 Multi-family mortgage 348 — — 348 47,550 47,898 — — Construction 360 242 — 602 21,560 22,162 — — Total commercial real estate loans 708 457 9,087 10,252 181,629 191,881 9,018 122 Commercial loans and leases: Commercial 124 44 290 458 23,330 23,788 90 200 Equipment financing — — 9 9 3,240 3,249 9 — Total commercial loans and leases 124 44 299 467 26,570 27,037 99 200 Consumer loans: Residential mortgage — 371 2,113 2,484 127,425 129,909 2,113 290 Home equity 191 265 2 458 45,012 45,470 — 717 Other consumer — — — — 110 110 — — Total consumer loans 191 636 2,115 2,942 172,547 175,489 2,113 1,007 Total acquired loans and leases 1,023 1,137 11,501 13,661 380,746 394,407 11,230 1,329 Total loans and leases $ 13,414 $ 3,308 $ 28,728 $ 45,450 $ 6,258,066 $ 6,303,516 $ 13,482 $ 24,097 At December 31, 2017 Past Due Loans and Leases Past Due Greater Than 90 Days and Accruing 31-60 Days 61-90 Days Greater Than 90 Days Total Current Total Loans and Leases Nonaccrual Loans and Leases (In Thousands) Originated: Commercial real estate loans: Commercial real estate $ 3,294 $ 391 $ 1,843 $ 5,528 $ 2,063,864 $ 2,069,392 $ — $ 3,182 Multi-family mortgage 6,141 2,590 — 8,731 727,190 735,921 — 608 Construction 6,537 330 860 7,727 132,411 140,138 — 860 Total commercial real estate loans 15,972 3,311 2,703 21,986 2,923,465 2,945,451 — 4,650 Commercial loans and leases: Commercial 1,344 597 7,724 9,665 687,160 696,825 — 10,365 Equipment financing 3,214 2,494 3,203 8,911 853,063 861,974 224 8,106 Condominium association 857 262 — 1,119 51,500 52,619 — — Total commercial loans and leases 5,415 3,353 10,927 19,695 1,591,723 1,611,418 224 18,471 Consumer loans: Residential mortgage 1,256 166 728 2,150 602,747 604,897 — 1,979 Home equity 643 19 32 694 313,495 314,189 1 132 Other consumer 238 20 28 286 14,381 14,667 — 43 Total consumer loans 2,137 205 788 3,130 930,623 933,753 1 2,154 Total originated loans and leases $ 23,524 $ 6,869 $ 14,418 $ 44,811 $ 5,445,811 $ 5,490,622 $ 225 $ 25,275 (Continued) At December 31, 2017 Past Due Loans and Leases Past Due Greater Than 90 Days and Accruing 31-60 Days 61-90 Days Greater Than 90 Days Total Current Total Loans and Leases Nonaccrual Loans and Leases (In Thousands) Acquired: Commercial real estate loans: Commercial real estate $ 1,008 $ — $ 656 $ 1,664 $ 103,913 $ 105,577 $ 586 $ 131 Multi-family mortgage — — 3 3 24,746 24,749 3 — Total commercial real estate loans 1,008 — 659 1,667 128,659 130,326 589 131 Commercial loans and leases: Commercial — 44 1,022 1,066 7,113 8,179 17 1,254 Equipment financing — — 13 13 4,501 4,514 13 — Total commercial loans and leases — 44 1,035 1,079 11,614 12,693 30 1,254 Consumer loans: Residential mortgage — 463 1,990 2,453 52,715 55,168 1,990 — Home equity 508 — 186 694 41,071 41,765 186 612 Other consumer — — — — 105 105 — — Total consumer loans 508 463 2,176 3,147 93,891 97,038 2,176 612 Total acquired loans and leases 1,516 507 3,870 5,893 234,164 240,057 2,795 1,997 Total loans and leases $ 25,040 $ 7,376 $ 18,288 $ 50,704 $ 5,679,975 $ 5,730,679 $ 3,020 $ 27,272 Commercial Real Estate Loans —As of December 31, 2018 , loans outstanding in the three classes within this segment expressed as a percentage of total loans and leases outstanding were as follows: commercial real estate loans ( 37.0% ); multi-family mortgage loans ( 13.4% ); and construction loans ( 2.7% ). Loans in this portfolio that are on nonaccrual status and/or risk-rated "substandard" or worse are evaluated on an individual loan basis for impairment. For non-impaired commercial real estate loans, loss factors are applied to outstanding loans by risk rating for each of the three classes in the portfolio. The factors applied are based primarily on historic loan loss experience and an assessment of internal and external factors and other relevant information. Commercial Loans and Leases —As of December 31, 2018 , loans and leases outstanding in the three classes within this segment expressed as a percent of total loans and leases outstanding were as follows: commercial loans and leases ( 11.7% ); equipment financing loans ( 15.6% ); and loans to condominium associations ( 0.8% ). Loans and leases in this portfolio that are on nonaccrual status and/or risk-rated "substandard" or worse are evaluated on an individual basis for impairment. For non-impaired commercial loans and leases, loss factors are applied to outstanding loans by risk rating for each of the three classes in the portfolio. Consumer Loans —As of December 31, 2018 , loans outstanding within the three classes within this segment expressed as a percent of total loans and leases outstanding were as follows: residential mortgage loans ( 12.4% ), home equity loans ( 6.0% ), and other consumer loans ( 0.4% ). Significant risk characteristics related to the residential mortgage and home equity loan portfolios are the geographic concentration of the properties financed within selected communities in the greater Boston and Providence metropolitan areas. The payment status and loan-to-value ratio are the primary credit quality indicator used for residential mortgage loans and home equity loans. Generally, loans are not made when the loan-to-value ratio exceeds 80% unless private mortgage insurance is obtained and/or there is a financially strong guarantor. Consumer loans that become 90 days or more past due, or are placed on nonaccrual regardless of past due status, are reviewed on an individual basis for impairment by assessing the net realizable value of underlying collateral and the economic condition of the borrower. Impaired Loans and Leases A loan is considered to be impaired when, based on current information and events, it is probable that the Company will be unable to collect all amounts due (both interest and principal) according to the contractual terms of the loan agreement. The Company has defined the population of impaired loans to include nonaccrual loans and troubled debt restructured loans. When the ultimate collectability of the total principal of an impaired loan or lease is in doubt and the loan is on nonaccrual status, all payments are applied to principal, under the cost recovery method. When the ultimate collectability of the total principal of an impaired loan or lease is not in doubt and the loan or lease is on nonaccrual status, contractual interest is credited to interest income when received, under the cash basis method. The following tables include the recorded investment and unpaid principal balances of impaired loans and leases with the related allowance amount, if applicable, for the originated and acquired loan and lease portfolios at the dates indicated. Also presented are the average recorded investments in the impaired loans and leases and the related amount of interest recognized during the period that the impaired loans were impaired. At December 31, 2018 At December 31, 2017 Recorded (1) Unpaid Related Recorded Investment (2) Unpaid Related (In Thousands) Originated: With no related allowance recorded: Commercial real estate $ 5,569 $ 5,545 $ — $ 9,978 $ 9,962 $ — Commercial 30,927 31,053 — 24,906 25,040 — Consumer 2,989 2,978 — 3,508 3,500 — Total originated with no related allowance recorded 39,485 39,576 — 38,392 38,502 — With an allowance recorded: Commercial real estate 396 396 5 3,056 3,056 — Commercial 8,224 8,208 2,961 8,912 8,862 3,105 Consumer 665 664 89 — — — Total originated with an allowance recorded 9,285 9,268 3,055 11,968 11,918 3,105 Total originated impaired loans and leases 48,770 48,844 3,055 50,360 50,420 3,105 Acquired: With no related allowance recorded: Commercial real estate 9,538 9,538 — 1,880 1,880 — Commercial 531 531 — 1,594 1,594 — Consumer 4,772 4,772 — 4,736 4,736 — Total acquired with no related allowance recorded 14,841 14,841 — 8,210 8,210 — With an allowance recorded: Consumer 154 154 26 115 115 22 Total acquired with an allowance recorded 154 154 26 115 115 22 Total acquired impaired loans and leases 14,995 14,995 26 8,325 8,325 22 Total impaired loans and leases $ 63,765 $ 63,839 $ 3,081 $ 58,685 $ 58,745 $ 3,127 __________________________________________________________________________ (1) Includes originated and acquired nonaccrual loans of $22.7 million and $1.3 million , respectively as of December 31, 2018 . (2) Includes originated and acquired nonaccrual loans of $24.9 million and $2.0 million , respectively as of December 31, 2017 . Year Ended December 31, 2018 December 31, 2017 December 31, 2016 Average Interest Average Interest Average Interest (In Thousands) Originated: With no related allowance recorded: Commercial real estate $ 6,484 $ 87 $ 10,181 $ 277 $ 6,608 $ 152 Commercial 26,514 993 24,950 747 23,445 600 Consumer 2,801 54 4,330 58 4,126 76 Total originated with no related allowance recorded 35,799 1,134 39,461 1,082 34,179 828 With an allowance recorded: Commercial real estate 99 — 3,271 162 4,715 195 Commercial 9,026 96 18,382 1 9,915 6 Consumer 835 11 — — 124 — Total originated with an allowance recorded 9,960 107 21,653 163 14,754 201 Total originated impaired loans and leases 45,759 1,241 61,114 1,245 48,933 1,029 Acquired: With no related allowance recorded: Commercial real estate 9,868 7 4,005 55 8,906 151 Commercial 1,212 16 2,280 31 4,255 75 Consumer 5,061 61 5,295 69 7,537 68 Total acquired with no related allowance recorded 16,141 84 11,580 155 20,698 294 With an allowance recorded: Commercial real estate — — — — 1,093 — Commercial — — — — 364 — Consumer 135 4 151 4 431 8 Total acquired with an allowance recorded 135 4 151 4 1,888 8 Total acquired impaired loans and leases 16,276 88 11,731 159 22,586 302 Total impaired loans and leases $ 62,035 $ 1,329 $ 72,845 $ 1,404 $ 71,519 $ 1,331 The following tables present information regarding impaired and non-impaired loans and leases at the dates indicated: At December 31, 2018 Commercial Real Estate Commercial Consumer Total (In Thousands) Allowance for Loan and Lease Losses: Originated: Individually evaluated for impairment $ 5 $ 2,961 $ 89 $ 3,055 Collectively evaluated for impairment 26,617 22,131 5,075 53,823 Total originated loans and leases 26,622 25,092 5,164 56,878 Acquired: Individually evaluated for impairment — — 26 26 Collectively evaluated for impairment 32 83 20 135 Acquired with deteriorated credit quality 1,533 108 12 1,653 Total acquired loans and leases 1,565 191 58 1,814 Total allowance for loan and lease losses $ 28,187 $ 25,283 $ 5,222 $ 58,692 Loans and Leases: Originated: Individually evaluated for impairment $ 5,610 $ 32,127 $ 3,502 $ 41,239 Collectively evaluated for impairment 3,154,245 1,709,794 1,003,831 5,867,870 Total originated loans and leases 3,159,855 1,741,921 1,007,333 5,

Premises and Equipment

Premises and Equipment	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Premises and Equipment	Premises and Equipment Premises and equipment consist of the following: At December 31, Estimated Useful Life 2018 2017 (In Thousands) (In Years) Land $ 12,300 $ 11,057 NA Fine art 533 495 NA Computer equipment 10,488 9,728 3 Vehicles 126 126 3 to 5 Core processing system and software 20,466 19,791 3 to 7.5 Furniture, fixtures and equipment 14,696 14,226 5 to 25 Office building and improvements 87,913 88,283 10 to 40 Total 146,522 143,706 Accumulated depreciation and amortization 70,140 63,423 Total premises and equipment $ 76,382 $ 80,283 Depreciation and amortization expense is calculated using the straight-line method and is included in occupancy and equipment and data processing expense in the Consolidated Statements of Income. For the years ended December 31, 2018 , 2017 and 2016 , depreciation and amortization expense related to premises and equipment totaled $7.5 million , $7.4 million , and $7.2 million , respectively. The increase in land is primarily the result of the purchase of land for the Jefferson Boulevard branch at Bank RI in Warwick, RI in 2018. The increase in computer equipment was primarily due to several equipment upgrades.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets The changes in the carrying value of goodwill for the periods indicated were as follows: Year Ended December 31, 2018 2017 2016 (In Thousands) Balance at beginning of year $ 137,890 $ 137,890 $ 137,890 Additions 22,537 — — Balance at end of year $ 160,427 $ 137,890 $ 137,890 The following is a summary of the Company's other intangible assets: At December 31, 2018 At December 31, 2017 Gross Accumulated Carrying Gross Accumulated Carrying (In Thousands) Other intangible assets: Core deposits $ 38,294 $ 33,297 $ 4,997 $ 36,172 $ 31,217 $ 4,955 Trade name 1,600 511 1,089 1,600 511 1,089 Trust relationship 1,568 1,568 — 1,568 1,568 — Other intangible 442 442 — 442 442 — Total other intangible assets $ 41,904 $ 35,818 $ 6,086 $ 39,782 $ 33,738 $ 6,044 At December 31, 2013, the Company concluded that the BankRI name would continue to be utilized in its marketing strategies; therefore, the trade name with carrying value of $1.1 million , has an indefinite life and ceased to amortize. The weighted-average amortization period for the core deposit intangible is 7.9 years. There were no impairment losses relating to other acquisition-related intangible assets recorded during the years ended December 31, 2018 , 2017 and 2016 . The estimated aggregate future amortization expense for other intangible assets for each of the next five years and thereafter is as follows: Year ended December 31: Amount (In Thousands) 2019 $ 1,699 2020 1,261 2021 850 2022 494 2023 263 Thereafter 430 Total $ 4,997

Other Assets

Other Assets	12 Months Ended
	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other Assets	Other Assets BOLI BOLI is recorded at the cash surrender value of the policies, less any applicable cash surrender charges, and is recorded in other assets. As of December 31, 2018 and 2017 , BankRI owned seven policies with a net cash surrender value of $39.9 million and $38.9 million , respectively. As of December 31, 2018 and 2017 , First Ipswich owned two policies with a net cash surrender value of $0.8 million , respectively. The Company recorded a total of $1.0 million , $1.0 million , and $1.1 million of tax exempt income from these nine policies in 2018 , 2017 , and 2016 , respectively. They are included in the Company’s other non-interest income in the consolidated statements of income. Affordable Housing Investments The Company began investing in affordable housing projects that benefit low- and moderate-income individuals in 2009. As of December 31, 2018 , the Company had investments in thirteen of these projects. The project sponsor or general partner controls the project's management. In each case, the Company is a limited partner with less than 50% of the outstanding equity interest in any single project. On January 1, 2015, the Company adopted ASU 2014-01, Accounting for Investments in Qualified Affordable Housing Projects , which required retrospective application and had an impact on net income for 2014 of $0.5 million and a cumulative effect on retained earnings of $1.1 million at January 1, 2015. Prior to the adoption of ASU 2014-01, the Company’s investments in qualified affordable housing projects were accounted for using the equity method. Under the equity method, operating losses or gains from these investments were included as a component of non-interest income in the Company's consolidated statements of income. ASU 2014-01 calls for the use of the proportional amortization method calculation and the operating losses or gains for these investments are included as a component of the provision for income taxes in the Company’s consolidated statements of income. Under the proportional amortization method, the initial costs of the investment in qualified affordable housing projects is amortized based on the tax credits and other benefits received. Further information regarding the Company's investments in affordable housing projects follows: At December 31, 2018 2017 (In Thousands) Investments in affordable housing projects included in other assets $ 10,895 $ 11,432 Unfunded commitments related to affordable housing projects included in other liabilities 1,115 1,933 Investment in affordable housing tax credits 1,885 1,745 Investment in affordable housing tax benefits 585 653 For the year ended December 31, 2018 2017 2016 (In Thousands) Investment amortization included in provision for income taxes $ 1,916 $ 1,844 $ 1,726 Amount recognized as income tax benefit 585 623 598

Deposits

Deposits	12 Months Ended
	Dec. 31, 2018
Banking and Thrift [Abstract]
Deposits	Deposits A summary of deposits follows: December 31, 2018 December 31, 2017 Amount Weighted Average Rate Amount Weighted Average Rate (Dollars in Thousands) Demand checking accounts $ 1,033,551 — % $ 942,583 — % NOW accounts 336,317 0.10 % 350,568 0.07 % Savings accounts 619,961 0.32 % 646,359 0.25 % Money market accounts 1,675,050 1.18 % 1,724,363 0.56 % Total core deposit accounts 3,664,879 0.60 % 3,663,873 0.31 % Certificate of deposit accounts maturing: Within six months 475,303 1.20 % 363,866 0.93 % After six months but within 1 year 562,018 1.40 % 342,500 1.09 % After 1 year but within 2 years 538,435 1.85 % 300,921 1.48 % After 2 years but within 3 years 95,806 2.16 % 90,805 1.87 % After 3 years but within 4 years 46,027 1.73 % 57,926 1.79 % After 4 years but within 5 years 71,556 2.57 % 50,380 2.02 % 5+ Years 20 1.98 % 1,072 1.03 % Total certificate of deposit accounts 1,789,165 1.58 % 1,207,470 1.27 % Total deposits $ 5,454,044 0.92 % $ 4,871,343 0.55 % Certificate of deposit accounts issued in amounts of $250,000 or more totaled $480.8 million and $265.8 million as of December 31, 2018 and 2017 , respectively. Interest expense on deposit balances is summarized as follows: Year Ended December 31, 2018 2017 2016 (In Thousands) Interest-bearing deposits: NOW accounts $ 283 $ 225 $ 209 Savings accounts 1,804 1,297 1,322 Money market accounts 15,369 8,863 7,549 Certificate of deposit accounts 24,522 12,903 10,990 Total interest-bearing deposits $ 41,978 $ 23,288 $ 20,070 Related Party Deposits Deposit accounts of directors, executive officers and their affiliates totaled $59.8 million and $41.4 million as of December 31, 2018 and 2017 , respectively. Collateral Pledged to Deposits As of December 31, 2018 and 2017 , $211.5 million and $165.5 million , respectively, of collateral was pledged for municipal deposits and Treasury Tax and Loan Deposits ("TT&L").

Borrowed Funds

Borrowed Funds	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Borrowed Funds	Borrowed Funds Borrowed funds are comprised of the following: At December 31, 2018 2017 (In Thousands) Advances from the FHLBB $ 784,375 $ 889,909 Subordinated debentures and notes 83,433 83,271 Other borrowed funds 52,734 47,639 Total borrowed funds $ 920,542 $ 1,020,819 Interest expense on borrowed funds for the periods indicated is as follows: Year Ended December 31, 2018 2017 2016 (In Thousands) Advances from the FHLBB $ 18,650 $ 11,330 $ 10,760 Subordinated debentures and notes 5,181 5,081 5,038 Other borrowed funds 385 170 116 Total interest expense on borrowed funds $ 24,216 $ 16,581 $ 15,914 Collateral Pledged to Borrowed Funds As of December 31, 2018 and 2017 , $2.4 billion and $1.9 billion , respectively, of investment securities and loans and leases, were pledged as collateral for repurchase agreements, swap agreements, FHLBB borrowings, and municipal deposits and TT&L. The Banks did not have any outstanding FRB borrowings as of December 31, 2018 and 2017 . FHLBB Advances FHLBB advances mature as follows: At December 31, 2018 2017 Amount Callable Amount Weighted Average Rate Amount Callable Amount Weighted Average Rate (Dollars in Thousands) Within 1 year $ 603,590 $ — 2.19 % $ 514,314 $ 55,000 1.43 % Over 1 year to 2 years 160,073 — 2.64 % 279,928 115,000 1.70 % Over 2 years to 3 years 580 — 3.07 % 16,026 — 0.47 % Over 3 years to 4 years 3,214 — 0.03 % 30,849 — 0.41 % Over 4 years to 5 years — — — % 33,217 — 0.30 % Over 5 years 16,918 — 3.45 % 15,575 — 3.95 % $ 784,375 $ — 2.30 % $ 889,909 $ 170,000 1.47 % Actual maturities of the advances may differ from those presented above since the FHLBB has the right to call certain advances prior to the scheduled maturity. The FHLBB advances are secured by blanket pledge agreements which require the Banks to maintain certain qualifying assets as collateral. The Banks did not have any FRB borrowings as of December 31, 2018 . Total available borrowing capacity for advances from the FHLBB and FRB was $2.2 billion as of December 31, 2018 for the Banks. The total amount of qualifying collateral for FHLBB and FRB borrowings was $3.2 billion as of December 31, 2018 . Other Borrowed Funds Information concerning other borrowed funds is as follows for the periods indicated below: Year Ended December 31, 2018 2017 (Dollars In Thousands) Outstanding at end of year $ 52,734 $ 47,639 Average outstanding for the year 46,079 45,908 Maximum outstanding at any month-end 55,144 54,064 Weighted average rate at end of year 0.16 % 0.46 % Weighted average rate paid for the year 0.83 % 0.37 % In addition to advances from the FHLBB and subordinated debentures and notes, the Company utilizes other funding sources as part of the overall liquidity strategy. Those funding sources include repurchase agreements, committed and uncommitted lines of credit with several financial institutions. The Company periodically enters into repurchase agreements with its larger deposit and commercial customers as part of its cash management services which are typically overnight borrowings. Repurchase agreements with customers increased $15.1 million to $52.7 million as of December 31, 2018 from $37.6 million as of December 31, 2017 . The Company has access to a $12.0 million committed line of credit as of December 31, 2018 . As of December 31, 2018 and December 31, 2017 , the Company did not have any borrowings on this committed line of credit outstanding. The Banks also have access to funding through several uncommitted lines of credit of $370.0 million . As of December 31, 2018 , the Company had no borrowings on outstanding uncommitted lines of credit as compared to December 31, 2017 , when the Company had $10.0 million in borrowings on outstanding uncommitted lines of credit. Subordinated Debentures and Notes On September 15, 2014, the Company issued $75.0 million of 6.0% fixed-to-floating subordinated notes due September 15, 2029. The Company is obligated to pay 6.0% interest semiannually between September 2014 and September 2024. Subsequently, the Company is obligated to pay 3-month LIBOR plus 3.315% quarterly until the notes mature in September 2029. The following table summarizes the Company's subordinated debentures and notes at the dates indicated. Carrying Amount Issue Date Rate Maturity Date Next Call Date December 31, 2018 December 31, 2017 (Dollars in Thousands) June 26, 2003 Variable; 3-month LIBOR + 3.10% June 26, 2033 March 26, 2019 $ 4,803 $ 4,778 March 17, 2004 Variable; 3-month LIBOR + 2.79% March 17, 2034 March 19, 2019 4,704 4,668 September 15, 2014 6.0% Fixed-to-Variable; 3-month LIBOR + 3.315% September 15, 2029 September 15, 2024 73,926 73,825 Total $ 83,433 $ 83,271 The above carrying amounts of the acquired subordinated debentures included $0.5 million of accretion adjustments and $1.1 million of capitalized debt issuance costs as of December 31, 2018 . This compares to $0.6 million of accretion adjustments and $1.2 million of capitalized debt issuance costs as of December 31, 2017 .

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Off-Balance Sheet Financial Instruments The Company is party to off-balance sheet financial instruments in the normal course of business to meet the financing needs of its customers and to reduce its own exposure to fluctuations in interest rates. These financial instruments include loan commitments, standby and commercial letters of credits, and loan level derivatives. According to GAAP, these financial instruments are not recorded in the financial statements until they are funded or related fees are incurred or received. The contract amounts reflect the extent of the involvement the Company has in particular classes of these instruments. Such commitments involve, to varying degrees, elements of credit risk and interest-rate risk in excess of the amount recognized in the consolidated balance sheets. The Company's exposure to credit loss in the event of non-performance by the counterparty is represented by the fair value of the instruments. The Company uses the same policies in making commitments and conditional obligations as it does for on-balance sheet instruments. Financial instruments with off-balance-sheet risk at the dates indicated follow: At December 31, 2018 2017 (In Thousands) Financial instruments whose contract amounts represent credit risk: Commitments to originate loans and leases: Commercial real estate $ 76,642 $ 76,653 Commercial 75,713 83,270 Residential mortgage 16,363 28,745 Unadvanced portion of loans and leases 707,997 571,668 Unused lines of credit: Home equity 487,476 407,552 Other consumer 50,404 34,191 Other commercial 347 323 Unused letters of credit: Financial standby letters of credit 11,491 12,422 Performance standby letters of credit 3,075 736 Commercial and similar letters of credit 4,573 184 Loan level derivatives: Receive fixed, pay variable 714,500 494,659 Pay fixed, receive variable 714,500 494,659 Risk participation-out agreements 100,531 36,627 Risk participation-in agreements 35,838 3,825 Foreign exchange contracts: Buys foreign currency, sells U.S. currency 6,573 1,495 Sells foreign currency, buys U.S. currency 6,582 1,502 Commitments to extend credit are agreements to lend to a customer as long as there is no violation of any condition established in the contract. Commitments generally have fixed expiration dates or other termination clauses and may require the payment of a fee by the customer. Since some of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. The Company evaluates each customer's creditworthiness on a case-by-case basis. The amount of collateral obtained, if any, is based on management's credit evaluation of the borrower. Standby and commercial letters of credits are conditional commitments issued by the Company to guarantee performance of a customer to a third party. These standby and commercial letters of credit are primarily issued to support the financing needs of the Company's commercial customers. The credit risk involved in issuing letters of credit is essentially the same as that involved in extending loans to customers. The liability for unfunded credit commitments, which is included in other liabilities, was $1.9 million and $1.7 million as of December 31, 2018 and December 31, 2017 , respectively. From time to time, the Company enters into loan level derivatives, risk participation agreements or foreign exchange contracts with commercial customers and third-party financial institutions. These derivatives allow the Company to offer long-term fixed-rate commercial loans while mitigating the interest-rate or foreign exchange risk of holding those loans. In a loan level derivative transaction, the Company lends to a commercial customer on a floating-rate basis and then enters into an loan level derivative with that customer. Concurrently, the Company enters into offsetting swaps with a third-party financial institution, effectively minimizing its net interest-rate risk exposure resulting from such transactions. The fair value of derivative assets and liabilities was $22.5 million and $22.2 million , respectively, as of December 31, 2018 . The fair value of derivative assets and liabilities was $9.0 million and $8.9 million , respectively, as of December 31, 2017 . The fair value of foreign exchange assets and liabilities was $131 thousand and $123 thousand , respectively, as of December 31, 2018 . The fair value of foreign exchange assets and liabilities was $72 thousand and $65 thousand as of December 31, 2017 . Lease Commitments The Company leases certain office space under various noncancellable operating leases. These leases have original terms ranging from 5 years to over 25 years. Certain leases contain renewal options and escalation clauses which can increase rental expenses based principally on the consumer price index and fair market rental value provisions. A summary of future minimum rental payments under such leases at the dates indicated follows: Year ended December 31, Minimum Rental Payments (In Thousands) 2019 $ 4,224 2020 4,932 2021 4,418 2022 3,602 2023 2,734 Thereafter 8,503 Total $ 28,413 Certain leases contain escalation clauses for real estate taxes and other expenditures, which are not included above. Total rental expense was $5.8 million in 2018 . This compares to total rent expense of $5.5 million in 2017 . In 2016 , total rent expense was $5.3 million . The increase in expense was due to the addition of two banking offices in Wakefield and Braintree, Massachusetts, and a rent increase for the Eastern Funding main office. A portion of the Company's headquarters was rented to third-party tenants which generated rental income of $0.4 million in 2018 , 2017 and 2016 respectively. Rental income was reported in non-interest income in the Company's consolidated statements of income. Legal Proceedings In the normal course of business, there are various outstanding legal proceedings. In the opinion of management, after consulting with legal counsel, the consolidated financial position and results of operations of the Company are not expected to be affected materially by the outcome of such proceedings.

Earnings per Share (EPS)

Earnings per Share (EPS)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Earnings per Share (EPS)	Earnings per Share ("EPS") The following table is a reconciliation of basic EPS and diluted EPS: For the year ended December 31, 2018 2017 2016 Basic Fully Diluted Basic Fully Diluted Basic Fully Diluted (Dollars in Thousands, Except Per Share Amounts) Numerator: Net income $ 83,062 $ 83,062 $ 50,518 $ 50,518 $ 52,362 $ 52,362 Denominator: Weighted average shares outstanding 79,669,668 79,669,668 74,459,508 74,459,508 70,261,954 70,261,954 Effect of dilutive securities — 239,583 — 351,900 — 182,129 Adjusted weighted average shares outstanding 79,669,668 79,909,251 74,459,508 74,811,408 70,261,954 70,444,083 EPS $ 1.04 $ 1.04 $ 0.68 $ 0.68 $ 0.74 $ 0.74

Comprehensive Income_(Loss)

Comprehensive Income/(Loss)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Comprehensive Income/(Loss)	Comprehensive Income/(Loss) Comprehensive income (loss) represents the sum of net income (loss) and other comprehensive income (loss). For the years ended December 31, 2018 , 2017 and 2016 , the Company’s other comprehensive income (loss) include the following two components: (i) unrealized holding losses on investment securities available-for-sale; and (ii) adjustment of accumulated obligation for postretirement benefits. Changes in accumulated other comprehensive loss by component, net of tax, were as follows for the periods indicated: Year Ended December 31, 2018 Investment Securities Available-for-Sale Postretirement Benefits Accumulated Other Comprehensive Loss (In Thousands) Balance at December 31, 2017 $ (6,113 ) $ 163 $ (5,950 ) Other comprehensive loss (3,599 ) 89 (3,510 ) Balance at December 31, 2018 $ (9,712 ) $ 252 $ (9,460 ) Year Ended December 31, 2017 Investment Securities Available-for-Sale Postretirement Benefits Accumulated Other Comprehensive Loss (In Thousands) Balance at December 31, 2016 $ (4,213 ) $ 395 $ (3,818 ) Other comprehensive loss (817 ) (252 ) (1,069 ) Reclassification due to adoption of ASU 2018-02 (1,083 ) 20 (1,063 ) Balance at December 31, 2017 $ (6,113 ) $ 163 $ (5,950 ) Year Ended December 31, 2016 Investment Securities Available-for-Sale Postretirement Benefits Accumulated Other Comprehensive Loss (In Thousands) Balance at December 31, 2015 $ (2,827 ) $ 351 $ (2,476 ) Other comprehensive (loss) income (1,386 ) 44 (1,342 ) Balance at December 31, 2016 $ (4,213 ) $ 395 $ (3,818 )

Derivatives and Hedging Activit

Derivatives and Hedging Activities	12 Months Ended
	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives and Hedging Activities	Derivatives and Hedging Activities The Company utilizes loan level derivatives which consist of interest-rate contracts (swaps, caps and floors), and risk participation agreements as part of the Company's interest-rate risk management strategy for certain assets and liabilities and not for speculative purposes. Based on the Company's intended use for the loan level derivatives at inception, the Company designates the derivative as either an economic hedge of an asset or liability, or a hedging instrument subject to the hedge accounting provisions of FASB ASC Topic 815, "Derivatives and Hedging". Interest-rate swap, cap and floor agreements are entered into as hedges against future interest-rate fluctuations on specifically identified assets or liabilities. The Company did not have derivative fair value hedges or derivative cash flow hedges as of December 31, 2018 or 2017 . Derivatives not designated as hedges are not speculative, but rather, result from a service the Company provides to certain customers for a fee. The Company executes loan level derivative products such as interest-rate swap agreements with commercial banking customers to aid them in managing their interest-rate risk. The interest-rate swap contracts allow the commercial banking customers to convert floating-rate loan payments to fixed-rate loan payments. The Company concurrently enters into offsetting swaps with a third party financial institution, effectively minimizing its net risk exposure resulting from such transactions. The third-party financial institution exchanges the customer's fixed-rate loan payments for floating-rate loan payments. As the interest-rate swap agreements associated with this program do not meet hedge accounting requirements, changes in the fair value are recognized directly in earnings. The Company utilizes risk participation agreements with other banks participating in commercial loan arrangements. Participating banks guarantee the performance on borrower-related interest rate swap contracts. Risk participation agreements are derivative financial instruments and are recorded at fair value. These derivatives are not designated as hedges and therefore, changes in fair value are recorded directly through earnings at each reporting period. The risk participation-out agreements have grown in tandem with the Company's increase in derivative activity. 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 Company offers foreign exchange contracts to commercial borrowers to accommodate their business needs. These foreign exchange contracts do not qualify as hedges for accounting purposes. To mitigate the market and liquidity risk associated with these foreign exchange contracts, the Company enters into similar offsetting positions. Asset derivatives and liability derivatives are included in other assets and accrued expenses and other liabilities on the consolidated balance sheets. The following tables presents the Company's customer related derivative positions for the periods indicated below for those derivatives not designated as hedging. Notional Amount Maturing Number of Positions Less than 1 year Less than 2 years Less than 3 years Less than 4 years Thereafter Total Fair Value December 31, 2018 (Dollars In Thousands) Loan level derivatives Receive fixed, pay variable 86 $ 1,931 $ 26,419 $ — $ 31,762 $ 654,388 $ 714,500 $ 6,081 Pay fixed, receive variable 86 1,931 26,419 — 31,762 654,388 714,500 6,081 Risk participation-out agreements 26 — 14,892 — — 85,639 100,531 344 Risk participation-in agreements 5 — — — — 35,838 35,838 84 Foreign exchange contracts Buys foreign currency, sells U.S. currency 22 $ 6,573 $ — $ — $ — $ — $ 6,573 $ 123 Sells foreign currency, buys U.S. currency 37 6,582 — — — — 6,582 131 Notional Amount Maturing Number of Positions Less than 1 year Less than 2 years Less than 3 years Less than 4 years Thereafter Total Fair Value December 31, 2017 (Dollars In Thousands) Loan level derivatives Receive fixed, pay variable 66 $ 3,903 $ 2,036 $ 27,992 $ — $ 460,728 $ 494,659 $ 8,865 Pay fixed, receive variable 66 3,903 2,036 27,992 — 460,728 494,659 8,865 Risk participation-out agreements 8 — — 8,613 — 28,014 36,627 65 Risk participation-in agreements 1 — — — — 3,825 3,825 10 Foreign exchange contracts Buys foreign currency, sells U.S. currency 22 $ 1,495 $ — $ — $ — $ — $ 1,495 $ 65 Sells foreign currency, buys U.S. currency 44 1,502 — — — — 1,502 72 Changes in the fair value are recognized directly in the Company's consolidated statements of income and are included in other non-interest income in the consolidated statements of income. The table below presents the gain (loss) recognized in income due to changes in the fair value for the year ended December 31, 2018 and 2017 . Year Ended December 31, 2018 2017 (In Thousands) Gain recognized in income on: Risk participation-out agreements 205 55 Foreign exchange contracts 1 7 Total $ 206 $ 62 By using derivative financial instruments, the Company exposes itself to credit risk which is the risk of failure by the counterparty to perform under the terms of the derivative contract. When the fair value of a derivative contract is positive, the counterparty owes the Company, which creates credit risk for the Company. When the fair value of a derivative is negative, the Company owes the counterparty and, therefore, it does not possess credit risk. The credit risk in derivative instruments is mitigated by entering into transactions with highly-rated counterparties that management believes to be creditworthy and by limiting the amount of exposure to each counterparty by either cross collateralizing the underlying hedged loan or through bilateral posting of collateral to cover exposure. As the swaps are subject to master netting agreements, the Company had limited exposure relating to loan level derivatives with institutional counterparties as of December 31, 2018 and 2017 . The estimated net credit risk exposure for derivative financial instruments was zero as of December 31, 2018 , and 2017 . Certain derivative agreements contain provisions that require the Company to post collateral if the derivative exposure exceeds a threshold amount. The Company posted collateral of $5.9 million and $26.7 million in the normal course of business as of December 31, 2018 and 2017 , respectively. The tables below present the offsetting of derivatives and amounts subject to master netting agreements not offset in the consolidated balance sheet at the dates indicated. At December 31, 2018 Gross Gross Amounts Statement of Financial Position Net Amounts Presented in the Statement of Financial Position Gross Amounts Not Offset in the Statement of Financial Position Net Amount Financial Instruments Pledged Cash Collateral Pledged (In Thousands) Asset derivatives Loan level derivatives $ 22,013 $ — $ 22,013 $ — $ 50 $ 21,963 Risk participation-out agreements 344 — 344 — — 344 Foreign exchange contracts 131 — 131 — — 131 Total $ 22,488 $ — $ 22,488 $ — $ 50 $ 22,438 Liability derivatives Loan level derivatives $ 22,013 $ — $ 22,013 $ 5,877 $ — $ 16,136 Risk participation-in agreements 84 — 84 — — 84 Foreign exchange contracts 123 — 123 — — 123 Total $ 22,220 $ — $ 22,220 $ 5,877 $ — $ 16,343 At December 31, 2017 Gross Gross Amounts Statement of Financial Position Net Amounts Presented in the Statement of Financial Position Gross Amounts Not Offset in the Statement of Financial Position Net Amount Financial Instruments Pledged Cash Collateral Pledged (In Thousands) Asset derivatives Loan level derivatives $ 8,865 $ — $ 8,865 $ — $ — $ 8,865 Risk participation-out agreements 65 — 65 — — 65 Foreign exchange contracts 72 — 72 — — 72 Total $ 9,002 $ — $ 9,002 $ — $ — $ 9,002 Liability derivatives Loan level derivatives $ 8,865 $ — $ 8,865 $ 25,159 $ 1,510 $ — Risk participation-in agreements 10 — 10 — — 10 Foreign exchange contracts 65 — 65 — — 65 Total $ 8,940 $ — $ 8,940 $ 25,159 $ 1,510 $ 75 The Company has agreements with certain of its derivative counterparties that contain credit-risk-related contingent provisions. These provisions provide the counterparty with the right to terminate its derivative positions and require the Company to settle its obligations under the agreements if the Company defaults on certain of its indebtedness or if the Company fails to maintain its status as a well-capitalized institution.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Income tax expense is comprised of the following amounts: Year Ended December 31, 2018 2017 2016 (In Thousands) Current provision: Federal $ 23,949 $ 27,825 $ 22,954 State 7,693 5,013 5,116 Total current provision 31,642 32,838 28,070 Deferred benefit (provision): Federal (4,323 ) 10,209 2,271 State (1,130 ) 589 51 Total deferred benefit (provision) (5,453 ) 10,798 2,322 Total provision for income taxes $ 26,189 $ 43,636 $ 30,392 Total provision for income taxes differed from the amounts computed by applying the statutory U.S. federal income tax rate of 21.0% in 2018 and 35.0% in 2017 and 2016 to income before tax expense as a result of the following: Year Ended December 31, 2018 2017 2016 (Dollars In Thousands) Expected income tax expense at statutory federal tax rate $ 23,675 $ 34,039 $ 29,965 State taxes, net of federal income tax benefit 5,184 3,641 3,358 Bank-owned life insurance (218 ) (364 ) (368 ) Tax-exempt interest income (487 ) (873 ) (826 ) Income attributable to noncontrolling interest in subsidiary (933 ) (870 ) (1,163 ) Merger and acquisition expense 32 138 — Tax Reform Act Adjustment (707 ) 8,965 — Investments in affordable housing projects (358 ) (653 ) (640 ) Other, net 1 (387 ) 66 Total provision for income taxes $ 26,189 $ 43,636 $ 30,392 Effective income tax rate 23.2 % 44.9 % 35.5 % The Company's effective tax rate was 23.2% as of December 31, 2018 compared to 44.9% as of December 31, 2017 . The decrease in the Company's effective tax rate from 2017 was primarily driven by the expected income tax expense, which was $10.4 million lower in 2018, as a result of the Tax Reform Act. Also, there was a $9.0 million Tax Reform Adjustment in 2017, the year of enactment. In 2018, the Company made an adjustment related to the Tax Reform Act that reduced the provision for income taxes by $0.7 million . On December 22, 2017, the Tax Reform Act was enacted, which represents the most comprehensive reform to the U.S. tax code in over thirty years. The majority of the provisions of the Tax Reform Act took effect on January 1, 2018. The Tax Reform Act lowers the Company’s federal tax rate from 35% to 21%. The Tax Reform Act also contains other provisions that may affect the Company currently or in future years. Among these are changes to the deductibility of meals and entertainment, the deductibility of executive compensation, accelerated expensing of depreciable property for assets placed in service after September 27, 2017 and before 2023, limits the deductibility of net interest expense, eliminated the corporate alternative minimum tax, limited net operating loss carryforwards to 80% of taxable income and other provisions. Recent changes in 2018 also include a parking disallowance in regards to employee parking, which the Company has taken into account in calculating the effective tax rate. As a result of the Tax Reform Act, in 2017, management re-valued the carrying value of our net deferred tax asset and investments in low income housing tax credits. The impact of the Tax Reform Act resulted in a write down of the carrying balance of net deferred tax assets and investments in affordable housing projects of $8.6 million and $0.3 million , respectively. The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and liabilities at the dates indicated are as follows: At December 31, 2018 2017 (In Thousands) Deferred tax assets: Allowance for loan and lease losses $ 15,936 $ 15,618 Deferred compensation 4,692 1,032 Supplemental Executive Retirement Plans 2,846 2,805 Unrealized loss on investment securities available-for-sale 2,737 1,728 Net operating loss carryforwards 976 415 Postretirement benefits 391 400 Nonaccrual interest 482 551 Accrued expense 372 563 Restricted stock and stock option plans 497 621 Employee stock ownership plan 106 124 Other 331 67 Total gross deferred tax assets 29,366 23,924 Deferred tax liabilities: Identified intangible assets and goodwill 2,428 2,778 Deferred loan origination costs, net 3,537 2,918 Depreciation 789 1,866 Prepaid expense 116 109 Acquisition fair value adjustments 1,001 1,192 Total gross deferred tax liabilities 7,871 8,863 Net deferred tax asset $ 21,495 $ 15,061 As of December 31, 2018 , the Company had net operating loss carryforwards for federal income tax purposes of $4.6 million gross which are available to offset future federal taxable income, if any, through 2020. Of this total net operating loss carryforward amount, $3.5 million is related to the Company's First Commons Bank transaction. The Company has determined that a valuation allowance is not required for any of its deferred tax assets because it believes that it is more likely than not that these assets will reverse against future taxable income. For federal income tax purposes, the Company has a $1.8 million reserve for credit losses which remains subject to recapture. If any portion of the reserve is used for purposes other than to absorb the losses for which it was established, approximately 150% of the amount actually used (limited to the amount of the reserve) would be subject to taxation in the year in which used. As the Company intends to use the reserve only to absorb credit losses, no provision has been made for the $0.5 million liability that would result if 100% of the reserve were recaptured. The Company did not have any unrecognized tax benefits accrued as income tax payables, receivables or as deferred tax items as of December 31, 2018 and 2017 . The Company files U.S. federal and state income tax returns. As of December 31, 2018 , the Company is subject to examination by the Massachusetts, Rhode Island and several other state tax authorities for tax years after December 31, 2014 .

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Stockholders' Equity	Stockholders' Equity Preferred Stock The Company is authorized to issue 50,000,000 shares of serial preferred stock, par value $0.01 per share, from time to time in one or more series subject to limitations of law. The Board of Directors is authorized to fix the designations, powers, preferences, limitations and rights of the shares of each such series. As of December 31, 2018 , there were no shares of preferred stock issued. Capital Distributions and Restrictions Thereon The Company is a legal entity separate and distinct from each of the Banks and Brookline Securities Corp. The Company's primary source of revenue is dividends paid to it by the Banks and Brookline Securities Corp. The FRB has authority to prohibit the Company from paying dividends to the Company's shareholders if such payment is deemed to be an unsafe or unsound practice. The FRB has indicated generally that it may be an unsafe or unsound practice for bank holding companies to pay dividends unless the bank holding company's net income over the preceding year is sufficient to fund the dividends and the expected rate of earnings retention is consistent with the organization's capital needs, asset quality and overall financial condition. The FRB also has the authority to use its enforcement powers to prohibit the Banks from paying dividends to the Company if, in its opinion, the payment of dividends would constitute an unsafe or unsound practice. Federal law also prohibits the payment of dividends by a bank that will result in the bank failing to meet its applicable capital requirements on a pro forma basis. In addition, a state bank that is a member of the Federal Reserve System may not declare or pay a dividend if the total of all dividends declared during the calendar year, including the proposed dividend, exceeds the sum of the bank's net income (as reportable in its Reports of Condition and Income) during the current calendar year and the retained net income of the prior two calendar years, unless the dividend has been approved by the FRB. Payment of dividends by a bank is also restricted pursuant to various state regulatory limitations, including the Massachusetts Division of Banks in the case of Brookline Bank and First Ipswich, and the Banking Division of the Rhode Island Department of Business Regulation in the case of BankRI. Common Stock Repurchases On February 4, 2016, the Company's Board of Directors authorized a stock repurchase program to acquire up to $10.0 million of the Company's common stock over a period of twelve months ending on January 31, 2017 (the "2016 Stock Repurchase Plan"). No shares were purchased under the 2016 Stock Repurchase Plan. On December 5, 2018, the Company’s Board of Directors authorized a stock repurchase program to acquire up to $10.0 million of the Company’s common stock over a period of twelve months ending on December 31, 2019 (the “2018 Stock Repurchase Plan”). As of December 31, 2018 , 725,583 shares of the Company’s common stock were repurchased under the 2018 Stock Repurchase Plan. On January 30, 2019, the Company’s Board of Directors authorized a stock repurchase program to acquire up to $10.0 million of the Company’s common stock over a period of eleven months ending on December 31, 2019 (the “2019 Stock Repurchase Plan”). There is no guarantee as to the exact number of shares, if any, to be repurchased by the Company under the 2019 Stock Repurchase Plan. As of January 31, 2017, no shares of stock were repurchased under the 2016 Stock Repurchased Plan. Repurchases may be made from time to time depending on market conditions and other factors, and will be conducted through open market or private transactions, through block trades, and pursuant to any trading plan that may be adopted in accordance with the Securities and Exchange Commission Rule 10b5-1. There is no guarantee as to the exact number of shares, if any, to be repurchased by the Company. Common Stock Issuance On March 1, 2018, the Company completed the acquisition of First Commons Bank. First Commons Bank was merged with and into the Company’s subsidiary bank, Brookline Bank. The Transaction qualified as a tax-free reorganization for federal income tax purposes. The total Transaction consideration was $56.0 million . First Commons Bank stockholders received, for each share of First Commons Bank common stock, the right to receive 1.089 shares of the Company’s common stock with cash in lieu of fractional shares, options, and warrants, resulting in a total cash consideration payment of $851 thousand and an increase to the Company’s outstanding shares of 3,481,477 shares. On, April 27, 2017, the Company entered into an underwriting agreement with Piper Jaffray & Co., as representative of the underwriters named therein (collectively, the “Underwriters”), to offer and sell 5,175,000 shares of the Company’s common stock, $0.01 par value per share at a public offering price of $14.50 per share in an underwritten public offering (the “Offering”). In conjunction with the Offering, the Company granted the Underwriters a 30-day option to purchase up to an additional 776,250 shares of its common stock. On May 2, 2017, the Company and the Underwriters closed the Offering. The Underwriters exercised their option resulting in a new issuance in the aggregate of 5,951,250 shares of the Company’s common stock at a price to the public of $14.50 per share. The Company received net proceeds of $82.0 million after deductions for underwriting discounts, commissions, and expenses. Restricted Retained Earnings As part of the stock offering in 2002 and as required by regulation, Brookline Bank established a liquidation account for the benefit of eligible account holders and supplemental eligible account holders who maintain their deposit accounts at Brookline Bank after the stock offering. In the unlikely event of a complete liquidation of Brookline Bank (and only in that event), eligible depositors who continue to maintain deposit accounts at Brookline Bank shall be entitled to receive a distribution from the liquidation account. Accordingly, retained earnings of the Company are deemed to be restricted up to the balance of the liquidation account. The liquidation account balance is reduced annually to the extent that eligible depositors have reduced their qualifying deposits as of each anniversary date. Subsequent increases in deposit account balances do not restore an account holder's interest in the liquidation account. The liquidation account totaled $13.0 million (unaudited), $15.1 million (unaudited), and $15.2 million (unaudited) at December 31, 2018 , 2017 and 2016 , respectively.

Regulatory Capital Requirements

Regulatory Capital Requirements	12 Months Ended
	Dec. 31, 2018
Banking and Thrift [Abstract]
Regulatory Capital Requirements	Regulatory Capital Requirements The Company's primary source of cash is dividends from the Banks and Brookline Securities Corp. The Banks are subject to certain restrictions on the amount of dividends that they may declare without prior regulatory approval. In addition, the dividends declared cannot be in excess of the amount which would cause the Banks to fall below the minimum required for capital adequacy purposes. The Company is a bank holding company within the meaning of the Bank Holding Company Act of 1956, as amended (the "BHCA") and as such, must comply with the capital requirements of the FRB at the consolidated level. As member banks of the FRB, Brookline Bank, BankRI and First Ipswich are also required to comply with the regulatory capital requirement of the FRB. The FRB has promulgated regulations imposing minimum capital requirements for bank holding companies and state member banks as well as prompt corrective action regulations for state member banks that implement the system of prompt corrective action established by Section 38 of the Federal Deposit Insurance Act, as amended (the "FDIA"). Under the prompt corrective action regulations in effect as of December 31, 2018 , a bank is "well-capitalized" if it has: (1) a total risk-based capital ratio of 10.0% or greater; (2) a Tier 1 risk-based capital ratio of 8.0% or greater; (3) a common equity Tier 1 capital ratio of 6.5% or greater; (4) a Tier 1 leverage ratio of 5.0% or greater; and (5) is not subject to any written agreement, order, capital directive or prompt corrective action directive to meet and maintain a specific capital level for any capital measure. 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, the Company and each of the Banks must meet specific capital guidelines that involve quantitative measures of the Company's and the Banks' assets, liabilities and certain off-balance sheet items as calculated under regulatory accounting practices. In addition, the prompt corrective action rules applicable to state member banks establish a framework of supervisory actions for state member banks that are not at least adequately capitalized. The Company's and the Banks' capital amounts and classification are also subject to qualitative judgments by the regulators about components, risk weightings, and other factors. Prompt corrective action provisions are not applicable to bank holding companies. Bank holding companies are not subject to prompt corrective action requirements. However, a bank holding company is considered "well capitalized" for purpose of the FRB's Regulation Y (which can affect eligibility for expedited application processes to make acquisitions and engage in new activities) if the bank holding company maintains on a consolidated basis a total risk-based capital ratio of 10.0% or greater and a Tier 1 risk-based capital ratio of 6.0% or greater and is not subject to any written agreement under capital directive or prompt correction action directive issued by the FRB to meet and maintain a specific capital level for any capital measure. Beginning January 1, 2019 , the Company and the Banks will have to maintain a capital conservation buffer composed of CET1 capital equal to 2.5% of risk-weighted assets above the amounts required to be adequately capitalized in order to avoid limitations on capital distributions, including dividend payments and certain discretionary bonus payments to executive officers. Capital ratios required to be considered well-capitalized exceed the ratios required under the capital conservation buffer requirement at December 31, 2018 . As of December 31, 2018 , the Company and the Banks are each under the primary regulation of, and must comply with, the capital requirements of the FRB. As of December 31, 2018 , the Company and the Banks exceeded all regulatory capital requirements and were considered “well-capitalized” under prompt corrective action regulations, as amended to reflect the changes under Basel III Capital Rules. The following table presents actual and required capital ratios as of December 31, 2018 for the Company and the Banks under the Basel III Capital Rules based on the phase-in provision of the Basel III Capital Rules and the minimum required capital levels as of January 1, 2019 when the Basel III Capital Rules have been fully phased in. Actual Minimum Required for Capital Adequacy Purposes Minimum Required for Fully Phased in Capital Adequacy Purposes plus Capital Conservation Buffer Minimum Required to be Considered “Well-Capitalized” Under Prompt Corrective Action Provisions Amount Ratio Amount Ratio Amount Ratio Amount Ratio (Dollars in Thousands) At December 31, 2018: Brookline Bancorp, Inc. Common equity Tier 1 capital ratio (1) $ 745,103 11.94 % $ 280,818 4.50 % $ 436,828 7.00 % N/A N/A Tier 1 leverage capital ratio (2) 765,089 10.58 % 289,259 4.00 % 289,259 4.00 % N/A N/A Tier 1 risk-based capital ratio (3) 765,089 12.26 % 374,432 6.00 % 530,445 8.50 % N/A N/A Total risk-based capital ratio (4) 899,563 14.42 % 499,064 8.00 % 655,022 10.50 % N/A N/A Brookline Bank Common equity Tier 1 capital ratio (1) $ 495,798 12.06 % $ 184,999 4.50 % $ 287,777 7.00 % $ 267,221 6.50 % Tier 1 leverage capital ratio (2) 506,277 11.02 % 183,767 4.00 % 183,767 4.00 % 229,708 5.00 % Tier 1 risk-based capital ratio (3) 506,277 12.32 % 246,563 6.00 % 349,298 8.50 % 328,751 8.00 % Total risk-based capital ratio (4) 545,533 13.27 % 328,882 8.00 % 431,658 10.50 % 411,102 10.00 % BankRI Common equity Tier 1 capital ratio (1) $ 209,670 11.37 % $ 82,983 4.50 % $ 129,084 7.00 % $ 119,864 6.50 % Tier 1 leverage capital ratio (2) 209,670 9.35 % 89,698 4.00 % 89,698 4.00 % 112,123 5.00 % Tier 1 risk-based capital ratio (3) 209,670 11.37 % 110,644 6.00 % 156,745 8.50 % 147,525 8.00 % Total risk-based capital ratio (4) 227,674 12.35 % 147,481 8.00 % 193,569 10.50 % 184,351 10.00 % First Ipswich Common equity Tier 1 capital ratio (1) $ 39,655 13.91 % $ 12,829 4.50 % $ 19,956 7.00 % $ 18,530 6.50 % Tier 1 leverage capital ratio (2) 39,655 9.59 % 16,540 4.00 % 16,540 4.00 % 20,675 5.00 % Tier 1 risk-based capital ratio (3) 39,655 13.91 % 17,105 6.00 % 24,232 8.50 % 22,807 8.00 % Total risk-based capital ratio (4) 42,944 15.06 % 22,812 8.00 % 29,941 10.50 % 28,515 10.00 % _______________________________________________________________________________ (1) Common equity Tier 1 capital ratio is calculated by dividing common equity Tier 1 capital by risk-weighted assets. The ratio was established as part of the implementation of Basel III, effective January 1, 2015. (2) Tier 1 leverage capital ratio is calculated by dividing Tier 1 capital by average assets. (3) Tier 1 risk-based capital ratio is calculated by dividing Tier 1 capital by risk-weighted assets. (4) Total risk-based capital ratio is calculated by dividing total capital by risk-weighted assets. The following table presents actual and required capital ratios as of December 31, 2017 for the Company and the Banks under the regulatory capital rules then in effect. Actual Minimum Required for Capital Adequacy Purposes Minimum Required for Fully Phased in Capital Adequacy Purposes plus Capital Conservation Buffer Minimum Required to be Considered “Well-Capitalized” Under Prompt Corrective Action Provisions Amount Ratio Amount Ratio Amount Ratio Amount Ratio (Dollars in Thousands) At December 31, 2017: Brookline Bancorp, Inc. Common equity Tier 1 capital ratio (1) $ 669,238 12.02 % $ 250,547 4.50 % $ 389,739 7.00 % N/A N/A Tier 1 leverage capital ratio (2) 687,299 10.43 % 263,585 4.00 % 263,585 4.00 % N/A N/A Tier 1 risk-based capital ratio (3) 687,299 12.34 % 334,181 6.00 % 473,423 8.50 % N/A N/A Total risk-based capital ratio (4) 821,373 14.75 % 445,490 8.00 % 584,706 10.50 % N/A N/A Brookline Bank Common equity Tier 1 capital ratio (1) $ 414,282 11.56 % $ 161,269 4.50 % $ 250,863 7.00 % $ 232,944 6.50 % Tier 1 leverage capital ratio (2) 423,035 10.35 % 163,492 4.00 % 163,492 4.00 % 204,365 5.00 % Tier 1 risk-based capital ratio (3) 423,035 11.81 % 214,920 6.00 % 304,471 8.50 % 286,561 8.00 % Total risk-based capital ratio (4) 463,986 12.95 % 286,632 8.00 % 376,205 10.50 % 358,290 10.00 % BankRI Common equity Tier 1 capital ratio (1) $ 193,849 11.38 % $ 76,654 4.50 % $ 119,239 7.00 % $ 110,722 6.50 % Tier 1 leverage capital ratio (2) 193,849 9.16 % 84,650 4.00 % 84,650 4.00 % 105,813 5.00 % Tier 1 risk-based capital ratio (3) 193,849 11.38 % 102,205 6.00 % 144,791 8.50 % 136,273 8.00 % Total risk-based capital ratio (4) 210,025 12.33 % 136,269 8.00 % 178,853 10.50 % 170,337 10.00 % First Ipswich Common equity Tier 1 capital ratio (1) $ 37,502 13.38 % $ 12,613 4.50 % $ 19,620 7.00 % $ 18,218 6.50 % Tier 1 leverage capital ratio (2) 37,502 9.44 % 15,891 4.00 % 15,891 4.00 % 19,863 5.00 % Tier 1 risk-based capital ratio (3) 37,502 13.38 % 16,817 6.00 % 23,824 8.50 % 22,423 8.00 % Total risk-based capital ratio (4) 40,625 14.50 % 22,414 8.00 % 29,418 10.50 % 28,017 10.00 % _______________________________________________________________________________ (1) Common equity Tier 1 capital ratio is calculated by dividing common equity Tier 1 capital by risk-weighted assets. The ratio was established as part of the implementation of Basel III, effective January 1, 2015. (2) Tier 1 leverage capital ratio is calculated by dividing Tier 1 capital by average assets. (3) Tier 1 risk-based capital ratio is calculated by dividing Tier 1 capital by risk-weighted assets. (4) Total risk-based capital ratio is calculated by dividing total capital by risk-weighted assets.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Employee Benefit Plans	Employee Benefit Plans Postretirement Benefits Postretirement benefits are provided for part of the annual expense of health insurance premiums for certain retired employees and their dependents. No contributions are made by the Company to invest in assets allocated for the purpose of funding this benefit obligation. The following table presents the change in plan assets and change in benefit obligation: Year Ended December 31, 2018 2017 2016 (In Thousands) Change in plan assets: Fair value of plan assets at beginning of year $ — $ — $ — Employer contributions 31 19 21 Benefits paid (31 ) (19 ) (21 ) Fair value of plan assets at end of year $ — $ — $ — Change in benefit obligation: Benefit obligation at beginning of year $ 1,534 $ 1,135 $ 1,188 Service cost 70 49 48 Interest cost 59 43 45 Estimated benefits paid (31 ) (19 ) (21 ) Actuarial loss (gain) (142 ) 326 (125 ) Benefit obligation at end of year $ 1,490 $ 1,534 $ 1,135 Funded status at end of year $ 1,490 $ 1,534 $ 1,135 Accumulated benefit obligation at end of year $ 1,490 $ 1,534 $ 1,135 The liability for the postretirement benefits included in accrued expenses and other liabilities was $1.5 million , $1.5 million , and $1.1 million as of December 31, 2018 , 2017 and 2016 , respectively. The following table presents the components of net periodic postretirement benefit cost and other amounts recognized in other comprehensive income: Year Ended December 31, 2018 2017 2016 (In Thousands) Net periodic benefit expense: Service cost $ 70 $ 49 $ 48 Interest cost 59 43 45 Prior service credit (21 ) (21 ) (21 ) Actuarial gain — (47 ) (42 ) Net periodic benefit expense $ 108 $ 24 $ 30 Changes in postretirement benefit obligation recognized in other comprehensive income: Net actuarial (loss) gain 142 $ (401 ) $ 90 Prior service credit (21 ) (21 ) (21 ) Total pre-tax changes in postretirement benefit obligation recognized in other comprehensive income $ 121 $ (422 ) $ 69 The discount rate used to determine the actuarial present value of projected postretirement benefit obligations was 4.22% in 2018 , 3.62% in 2017 and 4.15% in 2016 . The estimated prior service credit that will be amortized from accumulated other comprehensive income into net periodic benefit cost in 2019 is $85 thousand . The actual health care trend used to measure the accumulated postretirement benefit obligation in 2018 for plan participants below age 65 and for plan participants over age 65 was 3.1% and 2.4% , respectively. In 2017 , the rate for plan participants below age 65 and for plan participants over age 65 was (14.7)% and 33.9% , respectively. The health care trend rates for 2017 and 2018 are based on actual changes in medical premium rates for those years. The rates to be used in 2019 through 2023 are expected to be in the range of 6.2% to 5.3% and to decline gradually thereafter to 4.5% . Assumed health care trend rates may have a significant effect on the amounts reported for the postretirement benefit plan. A 1% change in assumed health care cost trend rates would have the following effects: Year Ended 1% Increase 1% Decrease (In Thousands) Effect on total service and interest cost components of net periodic postretirement benefit costs $ 31 $ (24 ) Effect on the accumulated postretirement benefit obligation 316 (250 ) 401(k) Plan The Company administers one 401(k) plan (the "Plan"), which is a qualified, tax-exempt profit-sharing plan with a salary deferral feature under Section 401(k) of the Internal Revenue Code. Each employee, excluding temporary employees, who has attained the age of 21 is eligible to participate in the plan by making voluntary contributions, subject to certain limits based on federal tax laws. In the Plan, the Company makes a matching contribution of the amount contributed by eligible employees, up to 5% of the employee's yearly compensation. Contributions to the Plan are subject to certain limits based on federal tax laws. Expenses associated with the plans were $3.2 million in 2018 , $2.6 million in 2017 , and $2.8 million in 2016 . Nonqualified Deferred Compensation Plan The Company also maintains a Nonqualified Deferred Compensation Plan (the "Nonqualified Plan") under which certain participants may contribute the amounts they are precluded from contributing to the Company's 401(k) plan because of the qualified plan limitations, and additional compensation deferrals that may be advantageous for personal income tax or other planning reasons. Expenses associated with the Nonqualified Plan in 2018 , 2017 and 2016 were $181.1 thousand , $128.5 thousand , and $91.8 thousand , respectively. Accrued liabilities associated with the Nonqualified Plan in 2018 , 2017 , and 2016 were $5.5 thousand , $80.2 thousand , and $154.8 thousand , respectively. Supplemental Executive Retirement Agreements The Company acquired two Supplemental Executive Retirement Plans (the "SERPs") as part of its acquisition of BankRI. The Company maintains the SERPs for certain senior executives under which participants are entitled to an annual retirement benefit. As of December 31, 2018 , there are 13 participants in the SERPs. The Company funded a Rabbi Trust to provide a partial funding source for the Company's liabilities under the SERPs. During 2016, a portion of the Company's BOLI assets were transferred into the Rabbi Trust as a replacement for the funds previously held in the Rabbi Trust. The Company records the liability for the SERPs based on an actuarial calculation in accordance with GAAP, and no actuarial gains and losses are recognized. Total expenses for benefits payable under the SERPs for the years ended December 31, 2018 , and 2017 was $0.5 million and $0.8 million , respectively. Aggregate benefits payable included in accrued expenses and other liabilities as of December 31, 2018 and 2017 were $12.1 million and $12.0 million , respectively. The nominal discount rate used to determine the actuarial present value of projected benefits under the agreements was 4.00% in the years 2018 and 2017 . Employee Stock Ownership Plan Brookline Bank established an Employee Stock Ownership Plan ("ESOP") on November 1, 1997. The Company's ESOP loan to Brookline Bank to purchase 546,986 shares of Company common stock is payable in quarterly installments over 30 years, bears interest at 8.50% per annum, matures December 31, 2021, and can be prepaid without penalty. The loan is repaid to the Company in the form of cash contributions from Brookline Bank, subject to federal tax law limits. The outstanding balance of the loan as of December 31, 2018 and 2017 , was $1.0 million and $1.3 million , respectively, and is eliminated in consolidation. Shares of common stock used as collateral to secure the loan are released and available for allocation to eligible employees as the principal and interest on the loan is paid. The ESOP was amended in 2015 to permit all eligible participants in the ESOP as of July 1, 2015 or any eligible participants after July 1, 2015 to be fully vested in the ESOP upon the date of eligibility. Dividends on released shares are credited to the participants' ESOP accounts. Dividends on unallocated shares of common stock are generally applied towards payment of the loan. ESOP shares committed to be released are considered outstanding in determining earnings per share. As of December 31, 2018 and 2017 , the ESOP held 109,950 and 142,332 unallocated shares, respectively at an aggregate cost of $0.6 million and $0.7 million , respectively. The market value of such shares as of December 31, 2018 and 2017 was $1.5 million and $2.3 million , respectively. Compensation and employee benefits expense related to the ESOP was $0.5 million in 2018 , $0.5 million in 2017 and $0.4 million in 2016 , based on the commitment to release to eligible employees 32,382 shares in 2018 , 34,356 shares in 2017 and 36,372 shares in 2016 . Recognition and Retention Plans As of December 31, 2018 , the Company had two active recognition and retention plans: the 2011 Restricted Stock Award Plan ("2011 RSA") with 500,000 authorized shares and the 2014 Equity Incentive Plan ("2014 Plan") with 1,750,000 authorized shares. The 2011 RSA and the 2014 Plan are collectively referred to as the "Plans". The purpose of the Plans is to promote the long-term financial success of the Company and its subsidiaries by providing a means to attract, retain and reward individuals who contribute to such success and to further align their interests with those of the Company's stockholders. Of the awarded shares, generally 50% vest ratably over three years with one-third of such shares vesting at each of the first, second and third anniversary dates of the awards. These are referred to as "time-based shares". The remaining 50% of each award has a cliff vesting schedule and will vest three years after the award date based on the level of the Company's achievement of identified performance targets in comparison to the level of achievement of such identified performance targets by a defined peer group comprised of 17 financial institutions. These are referred to as "performance-based shares". The specific performance measure targets relate to return on assets, return on tangible equity, asset quality and total stockholder return (share price appreciation from date of award plus dividends paid as a percent of the Company's common stock share price on the date of award). If a participant leaves the Company prior to the third anniversary date of an award, any unvested shares are forfeited. Dividends declared with respect to shares awarded will be held by the Company and paid to the participant only when the shares vest. Under all the Plans, shares of the Company's common stock were reserved for issuance as restricted stock awards to officers, employees, consultants and non-employee directors of the Company. Shares issued upon vesting may be either authorized but unissued shares or reacquired shares held by the Company as treasury shares. Any shares not issued because vesting requirements are not met will be retired back to treasury and be made available again for issuance under the Plans. Total expense for the Plans was $2.5 million in 2018 , $2.3 million in 2017 and $1.8 million in 2016 , respectively. Total income tax benefits on vested awards was $1.2 million in 2018 , $0.7 million in 2017 , and $0.3 million in 2016 . Dividends paid on unvested awards under the Plans, which are recognized as compensation expense, were $0.2 million in 2018 , $0.1 million in 2017 , and $0.1 million in 2016 . Activity under the recognition and retention plans was as follows: Restricted Stock Awards Outstanding Weighted Average Price per Share (Dollars in Thousands, Except Per Share Amounts) Recognition and Retention Plans: Outstanding at December 31, 2017 455,283 $ 12.64 Granted 169,582 18.40 Vested (195,660 ) 12.53 Forfeited / Canceled (38,570 ) 12.48 Outstanding at December 31, 2018 390,635 $ 15.21 Unrecognized compensation cost $ 3,735 Weighted average remaining recognition period (months) 22 Stock Option Plans The Company has an active equity incentive plan, the 2014 Plan. The prior plans, the "2003 Option Plan" and the "1999 Option Plan" were terminated on October 16, 2013 and April 19, 2009, respectively. The 2014 plan is an omnibus plan from which the Company may award up to 1,750,000 shares of restricted stock or stock options among other types of awards. Under all the stock option plans, shares of the Company's common stock were reserved for issuance to directors, employees, consultants and non-employee directors of the Company. Shares issued upon the exercise of a stock option may be either authorized but unissued shares or reacquired shares held by the Company as treasury shares. Any shares subject to an award which expire or are terminated unexercised will again be available for issuance under the plans. The exercise price of options awarded is the fair market value of the common stock of the Company on the date the award is made. Certain of the options include a reload feature whereby an optionee exercising an option by delivery of shares of common stock would automatically be granted an additional option at the fair market value of stock when such additional option is granted equal to the number of shares so delivered. If an individual to whom a stock option was granted ceases to maintain continuous service by reason of normal retirement, death or disability, or following a change in control, all options and rights granted and not fully exercisable become exercisable in full upon the happening of such an event and shall remain exercisable for a period ranging from 3 months to 5 years. No options were granted in 2018 , 2017 , or 2016 . There was no expense for the stock option plans in 2018 , 2017 , and 2016 . In accordance with the terms of the Plans, no dividend equivalent rights were paid to holders of unexercised vested options in 2018 , 2017 or 2016 . Activity under the option plans was as follows: Options Outstanding Weighted Average Exercise Price Per Share Aggregate Intrinsic Value Weighted Average Contractual Term (In Years) (Dollars in Thousands, Except Per Share Amounts) Employee Stock Options: Outstanding at December 31, 2017 50,000 $ 10.80 Granted — — Exercised (45,000 ) 10.90 Forfeited / Canceled — — Outstanding at December 31, 2018 5,000 $ 9.90 $ 20 1.8 Exercisable at December 31, 2018 5,000 $ 9.90 $ 20 1.8

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments A description of the valuation methodologies used for assets and liabilities measured at fair value on a recurring and non-recurring basis, as well as the general classification of such instruments pursuant to the valuation hierarchy, is set forth below. There were no changes in the valuation techniques used during 2018 and 2017 . Assets and Liabilities Recorded at Fair Value on a Recurring Basis The following table set forth the carrying value of assets and liabilities measured at fair value on a recurring basis at December 31, 2018 and 2017 : Carrying Value as of December 31, 2018 Level 1 Level 2 Level 3 Total (In Thousands) Assets: Investment securities available-for-sale: Debt securities: GSE debentures $ — $ 181,079 $ — $ 181,079 GSE CMOs — 103,130 — 103,130 GSE MBSs — 165,089 — 165,089 SBA commercial loan asset-backed securities — 51 — 51 Corporate debt obligations — 39,708 — 39,708 U.S. Treasury bonds — 13,736 — 13,736 Total investment securities available-for-sale $ — $ 502,793 $ — $ 502,793 Equity securities held-for-trading $ 3,235 $ 972 $ — $ 4,207 Loan level derivatives — 22,013 — 22,013 Risk participation-out agreements — 344 — 344 Foreign exchange contracts — 131 — 131 Liabilities: Loan level derivatives $ — $ 22,013 $ — $ 22,013 Risk participation-in agreements — 84 — 84 Foreign exchange contracts — 123 — 123 Carrying Value as of December 31, 2017 Level 1 Level 2 Level 3 Total (In Thousands) Assets: Investment securities available-for-sale: Debt securities: GSE debentures $ — $ 149,924 $ — $ 149,924 GSE CMOs — 127,022 — 127,022 GSE MBSs — 189,313 — 189,313 SBA commercial loan asset-backed securities — 72 — 72 Corporate debt obligations — 62,683 — 62,683 U.S. Treasury bonds — 8,730 — 8,730 Trust preferred securities — 1,398 — 1,398 Marketable equity securities — 982 — 982 Total investment securities available-for-sale $ — $ 540,124 $ — $ 540,124 Loan level derivatives — 8,865 — 8,865 Risk participation-out agreements — 65 — 65 Foreign exchange contracts — 72 — 72 Liabilities: Loan level derivatives $ — $ 8,865 $ — $ 8,865 Risk participation-in agreements — 10 — 10 Foreign exchange contracts — 65 — 65 Investment Securities Available-for-Sale The fair value of investment securities is based principally on market prices and dealer quotes received from third-party and nationally-recognized pricing services for identical investment securities such as U.S. Treasury and agency securities. During the 3rd quarter of 2018, the Company re-designated all equity securities as held-for-trading and are included in levels 1 and 2. These prices are validated by comparing the primary pricing source with an alternative pricing source when available. When quoted market prices for identical securities are unavailable, the Company uses market prices provided by independent pricing services based on recent trading activity and other observable information, including but not limited to market interest-rate curves, referenced credit spreads and estimated prepayment speeds where applicable. These investments include GSE debentures, GSE mortgage-related securities, SBA commercial loan asset backed securities, corporate debt securities, and trust preferred securities, all of which are included in Level 2. As of December 31, 2018 and December 31, 2017 , no investment securities were valued using pricing models included in Level 3. Additionally, management reviews changes in fair value from period to period and performs testing to ensure that prices received from the third parties are consistent with management's expectation of the market. Changes in the prices obtained from the pricing service are analyzed from month to month, taking into consideration changes in market conditions including changes in mortgage spreads, changes in U.S. Treasury security yields and changes in generic pricing of 15 -year and 30 -year securities. Additional analysis may include a review of prices provided by other independent parties, a yield analysis, a review of average life changes using Bloomberg analytics and a review of historical pricing for a particular security. Equity Securities Held-for-Trading As of December 31, 2017 , the Company had marketable equity securities classified as available-for-sale which were re-designated in 2018 as equity securities held-for-trading. The fair value of equity securities held-for-trading is based principally on market prices and dealer quotes received from third-party and nationally-recognized pricing services. The Company's equity securities are priced this way and are included in Level 1. These prices are validated by comparing the primary pricing source with an alternative pricing source when available. Loan Level Derivatives The fair values for the interest-rate swap assets and liabilities represent a Level 2 valuation and are based on settlement values adjusted for credit risks associated with the counterparties and the Company and observable market interest rate curves. Credit risk adjustments consider factors such as the likelihood of default by the Company and its counterparties, its net exposures and remaining contractual life. To date, the Company has not realized any losses due to a counterparty's inability to pay any net uncollateralized position. Refer also to Note 16, "Derivatives and Hedging Activities." There are no assets measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the year ended December 31, 2018 and December 31, 2017 . There were no transfers between levels for assets and liabilities recorded at fair value on a recurring basis during 2018 or 2017 . Assets and Liabilities Recorded at Fair Value on a Non-Recurring Basis Assets and liabilities measured at fair value on a non-recurring basis as of December 31, 2018 and 2017 are summarized below: Carrying Value as of December 31, 2018 Level 1 Level 2 Level 3 Total (In Thousands) Assets measured at fair value on a non-recurring basis: Collateral-dependent impaired loans and leases $ — $ — $ 11,451 $ 11,451 OREO — — 3,054 3,054 Repossessed assets — 965 — 965 Total assets measured at fair value on a non-recurring basis $ — $ 965 $ 14,505 $ 15,470 Carrying Value as of December 31, 2017 Level 1 Level 2 Level 3 Total (In Thousands) Assets measured at fair value on a non-recurring basis: Collateral-dependent impaired loans and leases $ — $ — $ 21,195 $ 21,195 OREO — — 3,235 3,235 Repossessed assets — 1,184 — 1,184 Total assets measured at fair value on a non-recurring basis $ — $ 1,184 $ 24,430 $ 25,614 Collateral-Dependent Impaired Loans and Leases For nonperforming loans and leases where the credit quality of the borrower has deteriorated significantly, fair values of the underlying collateral were estimated using purchase and sales agreements (Level 2), or comparable sales or recent appraisals (Level 3), adjusted for selling costs and other expenses. Other Real Estate Owned The Company records OREO at the lower of cost or fair value. In estimating fair value, the Company utilizes purchase and sales agreements (Level 2) or comparable sales, recent appraisals or cash flows discounted at an interest rate commensurate with the risk associated with these cash flows (Level 3), adjusted for selling costs and other expenses. Repossessed Assets Repossessed assets are carried at estimated fair value less costs to sell based on auction pricing (Level 2). The table below presents quantitative information about significant unobservable inputs (Level 3) for assets measured at fair value on a recurring basis at the dates indicated. Fair Value Valuation Technique At December 31, 2018 At December 31, 2017 (Dollars in Thousands) Collateral-dependent impaired loans and leases $ 11,451 $ 18,091 Appraisal of collateral (1) Other real estate owned 3,054 3,235 Appraisal of collateral (1) _______________________________________________________________________________ (1) Fair value is generally determined through independent appraisals of the underlying collateral. The Company may also use another available source of collateral assessment to determine a reasonable estimate of the fair value of the collateral. Appraisals may be adjusted by management for qualitative factors such as economic factors and estimated liquidation expenses. The range of the unobservable inputs used may vary but is generally 0% - 10% on the discount for costs to sell and 0% - 15% on appraisal adjustments. Summary of Estimated Fair Values of Financial Instruments The following table presents the carrying amount, estimated fair value, and placement in the fair value hierarchy of the Company's financial instruments at the dates indicated. This table excludes financial instruments for which the carrying amount approximates fair value. Financial assets for which the fair value approximates carrying value include cash and cash equivalents, restricted equity securities, and accrued interest receivable. Financial liabilities for which the fair value approximates carrying value include non-maturity deposits, short-term borrowings, and accrued interest payable. There were no transfers between levels during 2018 . Fair Value Measurements Carrying Value Estimated Fair Value Level 1 Inputs Level 2 Inputs Level 3 Inputs (In Thousands) At December 31, 2018 Financial assets: Investment securities held-to-maturity: GSE debentures $ 50,546 $ 49,601 $ — $ 49,601 $ — GSE MBSs 11,426 11,131 — 11,131 — Municipal obligations 52,304 51,598 — 51,598 — Foreign government obligations 500 500 — — 500 Loans held-for-sale 3,247 3,247 — 3,247 — Loans and leases, net 6,244,824 6,154,704 — — 6,154,704 Restricted equity securities 61,751 61,751 — — 61,751 Financial liabilities: Certificates of deposit 1,789,165 1,778,860 — 1,778,860 — Borrowed funds 920,542 886,545 — 886,545 — At December 31, 2017 Financial assets: Investment securities held-to-maturity: GSE debentures $ 41,612 $ 40,801 $ — $ 40,801 $ — GSE MBSs 13,923 13,705 — 13,705 — Municipal obligations 53,695 53,517 — 53,517 — Foreign government obligations 500 500 — — 500 Loans held-for-sale 2,628 2,628 — 2,628 — Loans and leases, net 5,672,087 5,594,543 — — 5,594,543 Restricted equity securities 59,369 59,369 — — 59,369 Financial liabilities: Certificates of deposit 1,207,470 1,198,201 — 1,198,201 — Borrowed funds 1,020,819 995,335 — 995,335 — Investment Securities Held-to-Maturity The fair values of certain investment securities held-to-maturity are estimated using market prices provided by independent pricing services based on recent trading activity and other observable information, including but not limited to market interest-rate curves, referenced credit spreads and estimated prepayment speeds where applicable. These investments include GSE debentures, GSE MBSs, and municipal obligations, all of which are included in Level 2. Additionally, fair values of foreign government obligations are based on comparisons to market prices of similar securities and are considered to be Level 3. Loans Held-for-Sale Fair value is measured using quoted market prices when available. These assets are typically categorized as Level 1. If quoted market prices are not available, comparable market values may be utilized. These assets are typically categorized as Level 2. Loans and Leases The fair values of performing loans and leases was estimated by segregating the portfolio into its primary loan and lease categories—commercial real estate mortgage, multi-family mortgage, construction, commercial, equipment financing, condominium association, residential mortgage, home equity and other consumer. These categories were further disaggregated based upon significant financial characteristics such as type of interest rate (fixed / variable) and payment status (current / past-due). The Company discounts the contractual cash flows for each loan category using interest rates currently being offered for loans with similar terms to borrowers of similar quality and incorporates estimates of future loan prepayments. Restricted Equity Securities The fair values of certain restricted equity securities are estimated using observable inputs adjusted for other unobservable information, including but not limited to probability assumptions and similar discounts where applicable. These restricted equity securities are considered to be Level 3. Deposits The fair values of deposit liabilities with no stated maturity (demand, NOW, savings and money market savings accounts) are equal to the carrying amounts payable on demand. The fair value of certificates of deposit represents contractual cash flows discounted using interest rates currently offered on deposits with similar characteristics and remaining maturities. The fair value estimates for deposits do not include the benefit that results from the low-cost funding provided by the Company's core deposit relationships (deposit-based intangibles). Borrowed Funds The fair value of federal funds purchased is equal to the amount borrowed. The fair value of FHLBB advances and repurchase agreements represents contractual repayments discounted using interest rates currently available for borrowings with similar characteristics and remaining maturities. The fair values reported for retail repurchase agreements are based on the discounted value of contractual cash flows. The discount rates used are representative of approximate rates currently offered on borrowings with similar characteristics and maturities. The fair values reported for subordinated deferrable interest debentures are based on the discounted value of contractual cash flows. The discount rates used are representative of approximate rates currently offered on instruments with similar terms and maturities.

Condensed Parent Company Financ

Condensed Parent Company Financial Statements	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Disclosure [Abstract]
Condensed Parent Company Financial Statements	Condensed Parent Company Financial Statements Condensed Parent Company Balance Sheets as of December 31, 2018 and 2017 and Statements of Income for the years ended December 31, 2018 , 2017 and 2016 are as follows. The Statement of Stockholders' Equity is not presented below as the parent company's stockholders' equity is that of the consolidated company. Balance Sheets At December 31, 2018 2017 (In Thousands) ASSETS Cash and due from banks $ 33,663 $ 5,511 Short-term investments 33 32 Total cash and cash equivalents 33,696 5,543 Equity securities held-for-trading 3,235 — ESOP loan to Brookline Bank 1,002 1,252 Intercompany loan to Brookline Bank 40,000 80,000 Restricted equity securities 101 100 Premises and equipment, net 4,318 6,032 Deferred tax asset 1,499 — Investment in subsidiaries, at equity 864,798 753,056 Goodwill 35,267 35,267 Other assets 5,400 6,627 Total assets $ 989,316 $ 887,877 LIABILITIES AND STOCKHOLDERS' EQUITY Borrowed funds $ 83,433 $ 83,271 Deferred tax liability — 608 Accrued expenses and other liabilities 5,743 168 Total liabilities 89,176 84,047 Stockholders' equity: Common stock, $0.01 par value; 200,000,000 shares authorized; 85,177,172 shares issued and 81,695,695 shares issued, respectively 852 817 Additional paid-in capital 755,629 699,976 Retained earnings, partially restricted 212,838 161,217 Accumulated other comprehensive loss (9,460 ) (5,950 ) Treasury stock, at cost; 5,020,025 shares and 4,440,665 shares, respectively (59,120 ) (51,454 ) Unallocated common stock held by ESOP; 109,950 shares and 142,332 shares, respectively (599 ) (776 ) Total stockholders' equity 900,140 803,830 Total liabilities and stockholders' equity $ 989,316 $ 887,877 Statements of Income Year Ended December 31, 2018 2017 2016 (In Thousands) Interest and dividend income: Dividend income from subsidiaries $ — $ 7,317 $ 109 Marketable and restricted equity securities 37 — — ESOP loan to Brookline Bank 98 120 141 Intercompany loan to Brookline Bank 1,722 532 — Total interest and dividend income 1,857 7,969 250 Interest expense: Borrowed funds 5,223 5,123 5,080 Net interest income (3,366 ) 2,846 (4,830 ) Non-interest income: Gain on securities, net 71 — — Other 16 — 15 Total non-interest income 87 — 15 Non-interest expense: Compensation and employee benefits 345 391 82 Occupancy 1,586 1,584 1,582 Equipment and data processing (1) (798 ) (1,011 ) (1,190 ) Directors' fees 417 453 700 Franchise taxes 321 180 180 Insurance 534 528 490 Professional services 364 470 245 Advertising and marketing 19 4 — Merger and acquisition expense 452 411 — Other (2) (1,140 ) (1,224 ) (1,300 ) Total non-interest expense 2,100 1,786 789 Loss before income taxes (5,379 ) 1,060 (5,604 ) Credit for income taxes (1,976 ) (1,944 ) (1,779 ) Loss before equity in undistributed income of subsidiaries (3,403 ) 3,004 (3,825 ) Equity in undistributed income of subsidiaries 86,465 47,514 56,187 Net income $ 83,062 $ 50,518 $ 52,362 _______________________________________________________________________________ (1) The Parent Company received a net benefit in 2018, 2017 and 2016 from the intercompany allocation of expense that is eliminated in consolidation. (2) The Parent Company received a net benefit in 2018, 2017 and 2016 from the intercompany allocation of expense that is eliminated in consolidation. Statements of Cash Flows Year Ended December 31, 2018 2017 2016 (In Thousands) Cash flows from operating activities: Net income attributable to parent company $ 83,062 $ 50,518 $ 52,362 Adjustments to reconcile net income to net cash provided from operating activities: Equity in undistributed income of subsidiaries (86,465 ) (47,514 ) (56,187 ) Depreciation of premises and equipment 3,073 2,856 2,735 Amortization of debt issuance costs 100 100 101 Equity securities held-for-trading (3,235 ) — — Other operating activities, net (31,014 ) (5,885 ) 30,895 Net cash (used for) provided from operating activities (34,479 ) 75 29,906 Cash flows from investing activities: Repayment of ESOP loan by Brookline Bank 250 250 250 Pay down (issuance) of intercompany loan to Brookline Bank 40,000 (80,000 ) — Purchase of restricted equity securities (1 ) — — Purchase of premises and equipment (1,359 ) (1,942 ) (641 ) Net cash provided from (used for) investing activities 38,890 (81,692 ) (391 ) Cash flows from financing activities: Proceeds from issuance of common stock — 81,943 — Common stock issued for acquisition 55,183 — — Payment of dividends on common stock (31,441 ) (27,035 ) (25,366 ) Net cash provided from (used for) financing activities 23,742 54,908 (25,366 ) Net increase (decrease) in cash and cash equivalents 28,153 (26,709 ) 4,149 Cash and cash equivalents at beginning of year 5,543 32,252 28,103 Cash and cash equivalents at end of year $ 33,696 $ 5,543 $ 32,252 Supplemental disclosures of cash flow information: Acquisition of First Commons Bank, N.A.: Fair value of assets acquired, net of cash and cash equivalents acquired $ 292,025 $ — $ — Fair value of liabilities assumed 278,988 — —

Quarterly Results of Operations

Quarterly Results of Operations (Unaudited)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Quarterly Results of Operations (Unaudited)	Quarterly Results of Operations (Unaudited) 2018 Quarters Fourth Third Second First (Dollars in Thousands Except Per Share Data) Interest and dividend income $ 83,544 $ 80,636 $ 78,074 $ 71,639 Interest expense 20,385 18,304 15,357 12,148 Net interest income 63,159 62,332 62,717 59,491 Provision for credit losses 123 2,717 1,470 641 Net interest income after provision for credit losses 63,036 59,615 61,247 58,850 Loan level derivative income, net 1,811 2,192 571 866 (Loss) gain on investment securities, net (692 ) (243 ) — 1,162 Gain on sales of loans and leases held-for-sale 327 535 722 299 Other non-interest income 5,015 4,585 4,233 3,841 Amortization of identified intangible assets (537 ) (537 ) (539 ) (467 ) Other non-interest expense (39,745 ) (36,773 ) (37,163 ) (39,471 ) Income before provision for income taxes 29,215 29,374 29,071 25,080 Provision for income taxes 7,055 6,140 7,342 5,652 Net income before noncontrolling interest in subsidiary 22,160 23,234 21,729 19,428 Less net income attributable to noncontrolling interest in subsidiary 1,022 774 898 795 Net income attributable to Brookline Bancorp, Inc. $ 21,138 $ 22,460 $ 20,831 $ 18,633 Earnings per share: Basic $ 0.26 $ 0.28 $ 0.26 $ 0.24 Diluted 0.26 0.28 0.26 0.24 Average common shares outstanding: Basic 80,258,489 80,315,050 80,184,977 77,879,593 Diluted 80,407,558 80,515,467 80,505,614 78,167,800 Common stock price: High $ 16.97 $ 19.05 $ 19.25 $ 17.05 Low 12.86 16.70 15.90 15.60 Dividends per share $ 0.105 $ 0.100 $ 0.100 $ 0.090 2017 Quarters Fourth Third Second First (Dollars in Thousands Except Per Share Data) Interest and dividend income $ 68,337 $ 67,176 $ 65,186 $ 62,351 Interest expense 10,680 10,333 9,603 9,253 Net interest income 57,657 56,843 55,583 53,098 Provision for credit losses 1,802 2,911 873 13,402 Net interest income after provision for credit losses 55,855 53,932 54,710 39,696 Loan level derivative income, net 755 844 186 402 Gain on sales of investment securities, net — — — 11,393 Gain on sales of loans and leases held-for-sale 935 1,049 307 353 Other non-interest income 4,125 4,080 3,984 3,760 Amortization of identified intangible assets (519 ) (519 ) (519 ) (532 ) Other non-interest expense (34,633 ) (34,889 ) (34,276 ) (33,224 ) Income before provision for income taxes 26,518 24,497 24,392 21,848 Provision for income taxes 18,712 8,330 8,759 7,835 Net income before noncontrolling interest in subsidiary 7,806 16,167 15,633 14,013 Less net income attributable to noncontrolling interest in subsidiary 979 801 753 568 Net income attributable to Brookline Bancorp, Inc. $ 6,827 $ 15,366 $ 14,880 $ 13,445 Earnings per share: Basic $ 0.09 $ 0.20 $ 0.20 $ 0.19 Diluted 0.09 0.20 0.20 0.19 Average common shares outstanding: Basic 76,583,712 76,452,539 74,325,013 70,386,766 Diluted 76,868,307 76,961,948 74,810,088 70,844,096 Common stock price: High $ 16.35 $ 15.50 $ 15.95 $ 16.75 Low 14.50 13.75 13.75 14.50 Dividends per share $ 0.09 $ 0.09 $ 0.09 $ 0.09

Revenue from Contracts with Cus

Revenue from Contracts with Customers (Notes)	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer	Revenue from Contracts with Customers Overview Revenue from contracts with customers in the scope of Accounting Standards Codification (“ASC”) ("Topic 606") is measured based on the consideration specified in the contract with a customer and excludes amounts collected on behalf of third parties. The Company recognizes revenue from contracts with customers when it satisfies its performance obligations. The Company’s performance obligations are generally satisfied as services are rendered and can either be satisfied at a point in time or over time. Unsatisfied performance obligations at the report date are not material to our consolidated financial statements. In certain cases, other parties are involved with providing services to our customers. If the Company is a principal in the transaction (providing services itself or through a third party on its behalf), revenues are reported based on the gross consideration received from the customer and any related expenses are reported gross in noninterest expense. If the Company is an agent in the transaction (referring to another party to provide services), the Company reports its net fee or commission retained as revenue. Accounting Policy Updates The Company adopted Topic 606, “Revenue from Contracts with Customers” effective January 1, 2018 and has applied the guidance to all contracts within the scope of Topic 606 as of that date. As a result, the Company has modified its accounting policy for revenue recognition as detailed in this Note. As discussed in Note 1, the Company applied Topic 606 using the modified retrospective method, therefore, the prior period comparative information has not been adjusted and continues to be reported under Topic 605. There was no cumulative effect adjustment as of January 1, 2018, and there were no material changes to our consolidated financial statements at or for the twelve months ended December 31, 2018 , as a result of adopting Topic 606. The Company applied the practical expedient pertaining to contracts with original expected duration of one year or less and does not disclose information about remaining performance obligations on such contracts. The Company also applied the practical expedient pertaining to contracts for which, at contract inception, the period between when the entity transfers the services and when the customer pays for those services will be one year or less. As such, the Company does not adjust the consideration from customers for the effects of a significant financing component. A substantial portion of the Company’s revenue is specifically excluded from the scope of Topic 606. This exclusion is associated with financial instruments, including interest income on loans and investment securities, in addition to loan derivative income and gains on loan and investment sales. For the revenue that is in-scope of Topic 606, the following is a description of principal activities from which the Company generates its revenue from contracts with customers, separated by the timing of revenue recognition. Revenue Recognized at a Point in Time The Company recognizes revenue that is transactional in nature and such revenue is earned at a point in time. Revenue that is recognized at a point in time includes card interchange fees (fee income related to debit card transactions), ATM fees, wire transfer fees, overdraft charge fees, and stop-payment and returned check fees. Additionally, revenue is collected from loan fees, such as letters of credit, line renewal fees and application fees. Such revenue is derived from transactional information and is recognized as revenue immediately as the transactions occur or upon providing the service to complete the customer’s transaction. Revenue Recognized Over Time The Company recognizes revenue over a period of time, generally monthly, as services are performed and performance obligations are satisfied. Such revenue includes commissions on investments, insurance sales and service charges on deposit accounts. Fee revenue from service charges on deposit accounts represent the service charges assessed to customers who hold deposit accounts at the Bank.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Eastern Funding, LLC Acquisition As of December 31, 2018, Brookline Bank, a wholly-owned subsidiary of the Company, held an 84.07 percent ownership interest in its subsidiary, Eastern Funding. As previously announced, on January 4, 2019, Brookline Bank completed the purchase of the remaining 15.93 percent interest in Eastern Funding for a total cash consideration of $35.9 million . On January 30, 2019, the Board of Directors approved a stock repurchase program authorizing management to repurchase up to $10.0 million of the Company's common stock over a period of eleven months ending December 31, 2019. The Company has evaluated subsequent events other than the matters described above and through the date of issuance.

Basis of Presentation (Policies

Basis of Presentation (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies
Basis of Accounting	The Company's consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles ("GAAP") as set forth by the Financial Accounting Standards Board ("FASB") in its Accounting Standards Codification and through the rules and interpretive releases of the Securities and Exchange Commission ("SEC") under the authority of federal securities laws.
Consolidation	The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All significant intercompany transactions and balances are eliminated in consolidation.
Use of Estimates	In preparing these consolidated financial statements, management is required to make significant estimates and assumptions that affect the reported amounts of assets, liabilities, income, expenses and disclosure of contingent assets and liabilities. Actual results could differ from those estimates based upon changing conditions, including economic conditions and future events. Material estimates that are particularly susceptible to significant changes in the near-term include the determination of the allowance for loan and lease losses, the determination of fair market values of assets and liabilities, including acquired loans, the review of goodwill and intangibles for impairment and the review of deferred tax assets for valuation allowance. The judgments used by management in applying these critical accounting policies may be affected by a further and prolonged deterioration in the economic environment, which may result in changes to future financial results. For example, subsequent evaluations of the loan and lease portfolio, in light of the factors then prevailing, may result in significant changes in the allowance for loan and lease losses in future periods, and the inability to collect outstanding principal may result in increased loan and lease losses.
Reclassification	Reclassification Certain previously reported amounts have been reclassified to conform to the current year's presentation.
Cash and Cash Equivalents	Cash and Cash Equivalents For purposes of reporting asset balances and cash flows, cash and cash equivalents includes cash on hand and due from banks (including cash items in process of clearing), interest-bearing deposits with banks, federal funds sold, money market mutual funds and other short-term investments with original maturities of three months or less.
Investment Securities	Investment Securities Investment securities, other than those reported as short-term investments, are classified at the time of purchase as "available-for-sale," "held-to-maturity," or "held-for-trading." Classification is periodically re-evaluated for consistency with the Company's goals and objectives. Equity investments in the Federal Home Loan Bank of Boston ("FHLBB"), the Federal Reserve Bank of Boston and other restricted equities are discussed in more detail in Note 5, "Restricted Equity Securities." Investment Securities Available-for-Sale, Held-to-Maturity, and Held-for-Trading Investment securities for which the Company has the positive intent and ability to hold to maturity are classified as held-to-maturity and carried at amortized cost. Those investment securities held for indefinite periods of time but not necessarily to maturity are classified as available-for-sale. Investment securities held for indefinite periods of time include investment securities that management intends to use as part of its asset/liability, liquidity, and/or capital management strategies and may be sold in response to changes in interest rates, maturities, asset/liability mix, liquidity needs, regulatory capital needs or other business factors. Investment securities available-for-sale are carried at estimated fair value, primarily obtained from a third-party pricing service, with unrealized gains and losses reported on an after-tax basis in stockholders' equity as accumulated other comprehensive income or loss. Investment securities expected to be held for very short term duration, used for hedging, or are marketable equity securities are typically designated held-for-trading. Held-for-trading securities are carried at estimated fair value principally based on market prices and dealer quotes received from third-party and nationally-recognized pricing services. Gains and losses for held-for-trading are reported on the income statement as gains on investment securities, net. As of December 31, 2018 and 2017 , the Company did not make any adjustments to the prices provided by the third-party pricing service. Security transactions are recorded on the trade date. Realized gains and losses are determined using the specific identification method and are recorded in non-interest income. Interest and dividends on securities are recorded using the accrual method. Premiums and discounts on securities are amortized or accreted into interest income using the level-yield method over the remaining period to contractual maturity, adjusted for the effect of actual prepayments in the case of mortgage-backed securities ("MBSs") and collateralized mortgage obligations ("CMOs"). These estimates of prepayment assumptions are made based upon the actual performance of the underlying security, current interest rates, the general market consensus regarding changes in mortgage interest rates, the contractual repayment terms of the underlying loans, the priority rights of the investors to the cash flows from the mortgage securities and other economic conditions. When differences arise between anticipated prepayments and actual prepayments, the effective yield is recalculated to reflect actual payments to date and anticipated future payments. Unamortized premium or discount is adjusted to the amount that would have existed had the new effective yield been applied since purchase, with a corresponding charge or credit to interest income. Management evaluates securities for other-than-temporary impairment ("OTTI") on a periodic basis. Factors considered in determining whether an impairment is OTTI include: (1) the length of time and the extent to which the fair value has been less than amortized cost, (2) projected future cash flows, (3) the financial condition and near-term prospects of the issuers, and (4) the intent and ability of the Company to hold the investment for a period of time sufficient to allow for any anticipated recovery in fair value. The Company records an OTTI loss in an amount equal to the entire difference between the fair value and amortized cost if: (1) the Company intends to sell an impaired investment security, (2) it is more likely than not that the Company will be required to sell the investment security before its amortized cost, or (3) for debt securities, the present value of expected future cash flows is not sufficient to recover the entire amortized cost basis. If an investment security is determined to be OTTI but the Company does not intend to sell the investment security, only the credit portion of the estimated loss is recognized in earnings, with the non credit portion of the loss recognized in other comprehensive income. Restricted Equity Securities The Company invests in the stock of the FHLBB, the Federal Reserve Bank of Boston and a small amount of other restricted securities. No ready market exists for these stocks, and they have no quoted market values. The Banks, as members of the FHLBB, are required to maintain investments in the capital stock of the FHLBB equal to their membership base investments plus an activity-based investment determined according to the Banks' level of outstanding FHLBB advances. Federal Reserve Bank of Boston stock was purchased and is redeemable at par.
Loans	Loans Originated Loans Loans the Company originates for the portfolio, and for which it has the intent and ability to hold to maturity, are reported at amortized cost, inclusive of deferred loan origination fees and expenses, less unadvanced funds due borrowers on loans and the allowance for loan and lease losses. Interest income on loans and leases originated for the portfolio is accrued on unpaid principal balances as earned. Loan origination fees and direct loan origination costs are deferred, and the net fee or cost is recognized in interest income using the interest method. Deferred amounts are recognized for fixed-rate loans over the contractual life of the loans and for adjustable-rate loans over the period of time required to adjust the contractual interest rate to a yield approximating a market rate at the origination date. If a loan is prepaid, the unamortized portion of the loan origination costs, including third party referral related costs not subject to rebate from the dealer, is charged to income. Loans and Leases Held-for-Sale Management identifies and designates certain newly originated loans and leases for sale to specific financial institutions, subject to the underwriting criteria of those financial institutions. These loans and leases are held for sale and are carried at the lower of cost or market as determined in the aggregate. Deferred loan fees and costs are included in the determination of the gain or loss on sale. Acquired Loans Acquired loans that have evidence of deterioration of credit quality since origination and for which it is probable, at acquisition, that the Company will be unable to collect all contractually required payments receivable are initially recorded at fair value (as determined by the present value of expected future cash flows) with no valuation allowance. The difference between the undiscounted cash flows expected at acquisition and the recorded fair value of the loan, or the “accretable yield,” is recognized as interest income on a level-yield method over the life of the loan. Contractually required payments for interest and principal that exceed the undiscounted cash flows expected at acquisition, or the “nonaccretable difference,” are not recognized as a yield adjustment or as a loss accrual or a valuation allowance. Increases in expected cash flows subsequent to the initial investment are recognized prospectively through adjustment of the yield on the loan over its remaining life. Decreases in expected cash flows are recognized as impairment. Valuation allowances on these impaired loans reflect only losses incurred after the acquisition (meaning the present value of all cash flows expected at acquisition that ultimately are not to be received). For the First Commons Bank portfolio, minimal loss is expected from the loan portfolio based on historical performance, management’s due diligence, and market conditions. Therefore, the fair value of the loan portfolio was calculated on an individual loan basis using a discounted cash flow analysis factoring in the contractual terms of the loans, current market pricing, and prepayment expectations.
Non-Performing Loans	Nonperforming Loans Nonaccrual Loans Accrual of interest on loans generally is discontinued when contractual payment of principal or interest becomes past due 90 days or, if in management's judgment, reasonable doubt exists as to the full timely collection of interest. Exceptions may be made if the loan has matured and is in the process of renewal or is well-secured and in the process of collection. When a loan is placed on nonaccrual status, interest accruals cease and uncollected accrued interest is reversed and charged against current interest income. Interest payments on nonaccrual loans are generally applied to principal. If collection of the principal is reasonably assured, interest payments are recognized as income on the cash basis. Loans are generally returned to accrual status when principal and interest payments are current, full collectability of principal and interest is reasonably assured and a consistent record of at least six consecutive months of performance has been achieved. Impaired Loans A loan is considered to be impaired when, based on current information and events, it is probable that the Company will be unable to collect all amounts due (both interest and principal) according to the contractual terms of the loan agreement. Smaller-balance, homogeneous loans that are evaluated collectively for impairment, such as residential, home equity and other consumer loans are specifically excluded from the impaired loan portfolio except where the loan is classified as a troubled debt restructuring. The Company has defined the population of impaired loans to include nonaccrual loans and troubled debt restructured ("TDR") loans. When the ultimate collectability of the total principal of an impaired loan or lease is in doubt and the loan is on nonaccrual status, all payments are applied to principal, under the cost recovery method. When the ultimate collectability of the total principal of an impaired loan or lease is not in doubt and the loan or lease is on nonaccrual status, contractual interest is credited to interest income when received, under the cash basis method. The value of an impaired loan is measured based upon the present value of expected future cash flows discounted at the loan's effective interest rate, or the fair value of the collateral if the loan is collateral-dependent and its payment is expected solely based on the underlying collateral. For impaired loans deemed collateral dependent, where impairment is measured using the fair value of the collateral, the Company will either obtain a new appraisal or use another available source of collateral assessment to determine a reasonable estimate of the fair value of the collateral. Interest collected on impaired loans is either applied against principal or reported as income according to management's judgment as to the collectability of principal. If management does not consider a loan ultimately collectible within an acceptable time frame, payments are applied as principal to reduce the loan balance. If full collection of the remaining recorded investment should subsequently occur, interest receipts are recorded as interest income on a cash basis. Troubled Debt Restructured Loans In cases where a borrower experiences financial difficulties and the Company makes certain concessionary modifications to contractual terms, the loan is classified as a TDR loan. In determining whether a debtor is experiencing financial difficulties, the Company considers, among other factors, whether the debtor is in payment default or is likely to be in payment default in the foreseeable future without the modification, if the debtor declared or is in the process of declaring bankruptcy, there is substantial doubt that the debtor will continue as a going concern, the debtor's entity-specific projected cash flows will not be sufficient to service its debt, or the debtor cannot obtain funds from sources other than the existing creditors at market terms for debt with similar risk characteristics. Large groups of small-balance homogeneous loans such as residential real estate, residential construction, home equity and other consumer portfolios are collectively evaluated for impairment. As such, the Company does not typically identify individual loans within these groupings as impaired loans or for impairment evaluation and disclosure. However, the Company evaluates all TDRs for impairment on an individual loan basis regardless of loan type. Modifications may include interest-rate reductions, short-term (defined as one year or less) changes in payment structure to interest-only payments, short-term extensions of the loan's original contractual term, or less frequently, principal forgiveness, interest capitalization, forbearance and other actions intended to minimize economic loss and avoid foreclosure or repossession of collateral. Typically, TDRs are placed on nonaccrual status and reported as nonperforming loans. Generally, a nonaccrual loan that is restructured remains on nonaccrual for a period of six months to demonstrate that the borrower can meet the restructured terms; however, performance prior to the restructuring, or significant events that coincide with the restructuring, are considered in assessing whether the borrower can meet the new terms and may result in the loan being returned to accrual status at the time of restructuring or after a shorter performance period. If the borrower's ability to meet the revised payment schedule is not reasonably assured, the loan remains classified as a nonaccrual loan. Loans restructured at an interest rate equal to or greater than that of a new loan with comparable risk at the time the loan agreement is modified may be excluded from restructured loan disclosures in years subsequent to the restructuring if they are in compliance with the modified terms.
Allowance for Loan and Lease Losses	Allowance for Loan and Lease Losses Management has established a methodology to determine the adequacy of the allowance for loan and lease losses that assesses the risks and losses inherent in the loan and lease portfolio. Additions to the allowance for loan and lease losses are made by charges to the provision for credit losses. Losses on loans and leases are charged off against the allowance when all or a portion of a loan or lease is considered uncollectible. Subsequent recoveries on loans previously charged off, if any, are credited to the allowance when realized. Management uses a consistent and systematic process and methodology to evaluate the adequacy of the allowance for loan and lease losses on a quarterly basis. For purposes of determining the allowance for loan and lease losses, the Company has segmented certain loans and leases in the portfolio by product type into the following segments: (1) commercial real estate loans, (2) commercial loans and leases, (3) and consumer loans. Portfolio segments are further disaggregated into classes based on the associated risks within the segments. Commercial real estate loans are divided into three classes: commercial real estate mortgage loans, multi-family mortgage loans, and construction loans. Commercial loans and leases are divided into three classes: commercial loans which includes taxi medallion loans, equipment financing, and loans to condominium associations. Consumer loans are divided into three classes: residential mortgage loans, home equity loans, and other consumer loans. A formula-based credit evaluation approach is applied to each group, coupled with an analysis of certain loans for impairment. The general allowance related to loans collectively evaluated for impairment is determined using a formula-based approach utilizing the risk ratings of individual credits and loss factors derived from historic portfolio loss rates, which include estimates of incurred losses over an estimated loss emergence period (“LEP”). The LEP was generated utilizing a charge-off look-back analysis which studied the time from the first indication of elevated risk of repayment (or other early event indicating a problem) to eventual charge-off to support the LEP considered in the allowance calculation. This reserving methodology established the approximate number of months of LEP that represents incurred losses for each portfolio. In addition to quantitative measures, relevant qualitative factors include, but are not limited to: (1) levels and trends in past due and impaired loans, (2) levels and trends in charge-offs, (3) changes in underwriting standards, policy exceptions, and credit policy, (4) experience of lending management and staff, (5) economic trends, (6) industry conditions, (7) effects of changes in credit concentrations, (8) interest rate environment, and (9) regulatory and other changes. The general allowance related to the acquired loans collectively evaluated for impairment is determined based upon the degree, if any, of deterioration in the pooled loans subsequent to acquisition. The qualitative factors used in the determination are the same as those used for originated loans. During 2015, the Company enhanced and refined its general allowance methodology. Under the enhanced methodology, management combined the historical loss histories of the Banks to generate a single set of historical loss ratios. Management believes it is appropriate to aggregate the ratios as the Banks share common environmental factors, operate in similar geographic markets, and utilize common underwriting standards in accordance with the Company's Credit Policy. In prior periods, a historical loss history applicable to each Bank was used. Management employed a similar analysis for the consolidation of the qualitative factors as it did for the quantitative factors. Again, management believes the realignment of the existing nine qualitative factors used at each of the Banks into a single group of factors used for the Company is appropriate based on the commonality of environmental factors, markets and underwriting standards among the Banks. Prior to 2015, each of the Banks utilized a set of qualitative factors applicable to each Bank. The Company’s December 31, 2018 allowance calculation included a further segmentation of the commercial loans and leases to reflect the increased risk in the Company’s taxi medallion portfolio. As of December 31, 2018 , this portfolio is approximately $13.7 million . Based on industry conditions, management established a loss factor for this portfolio that best represents the changing risks associated with it. Based on the refinements to the Company’s allowance methodology discussed above, management determined that the potential risks anticipated by the unallocated allowance are now incorporated into the allowance methodology, making the unallocated allowance unnecessary. Prior to 2015, the unallocated allowance was used to recognize the estimated risk associated with the allocated general and specific allowances. It incorporated management’s evaluation of existing conditions that were not included in the allocated allowance determinations and provided for losses that arise outside of the ordinary course of business. Specific valuation allowances are established for impaired originated loans with book values greater than the discounted present value of expected future cash flows or, in the case of collateral-dependent impaired loans, for any excess of a loan's book balance and the fair value of its underlying collateral. Specific valuation allowances are established for acquired loans with deterioration in the discounted present value of expected future cash flows since acquisitions or, in the case of collateral dependent impaired loans, for any increase in the excess of a loan's book balance greater than the fair value of its underlying collateral. A specific valuation allowance for losses on TDR loans is determined by comparing the net carrying amount of the troubled debt restructured loan with the restructured loan's cash flows discounted at the original effective rate. Impaired loans are reviewed quarterly with adjustments made to the calculated reserve as necessary. As of December 31, 2018 , management believes that the methodology for calculating the allowance is sound and that the allowance provides a reasonable basis for determining and reporting on probable losses in the Company’s loan portfolios. Liability for Unfunded Commitments In the ordinary course of business, the Company enters into commitments to extend credit, commercial letters of credit, and standby letters of credit. Such financial instruments are recorded in the financial statements when they become payable. The credit risk associated with these commitments is evaluated in a manner similar to the allowance for loan losses.
Premises and Equipment	Premises and Equipment Premises and equipment are carried at cost less accumulated depreciation and amortization, except for land which is carried at cost. Premises and equipment are depreciated using the straight-line method over the estimated useful life of the assets. Leasehold improvements are amortized using the straight-line method over the shorter of the lease term or the estimated useful life of the improvements. Costs related to internal-use software development projects that provide significant new functionality are capitalized. Internal-use software is software acquired or modified solely to meet the Company's needs and for which there is no plan to market the software externally. Direct and indirect costs associated with the application development stage of internal use software are capitalized until such time that the software is substantially complete and ready for its intended use. Capitalized costs are amortized on a straight-line basis over the remaining estimated life of the software. Computer software and development costs incurred in the preliminary project stage, as well as training and maintenance costs, are expensed as incurred.
Leases	Leases The Company leases properties for offices and branches in the states of Massachusetts, Rhode Island and New York. Lease terms range from five years to over 25 years with options to renew. Management performs an analysis to determine proper lease accounting at lease inception and for each renewal. If a lease meets any of the following four criteria, the lease is classified as capital lease. The four criteria are: transfer of ownership by the end of lease term; contains bargain purchase option; lease term is at least 75% of the property’s estimated remaining economic life; or present value of the minimum lease payment is at least 90% of the fair value of the leased property. All leases are classified as operating leases and rental payments are expensed as incurred. Certain leases contain rent escalation clauses which are amortized over the life of the lease under the straight-line method.
Bank-Owned Life Insurance	Bank-Owned Life Insurance The Company acquired bank-owned life insurance ("BOLI") plans as part of its acquisitions of First Ipswich and BankRI. BOLI represents life insurance on the lives of certain current and former employees who have provided positive consent allowing their employer to be the beneficiary of such policies. BankRI and First Ipswich are the beneficiaries of their respective policies. BankRI and First Ipswich utilize BOLI as tax-efficient financing for their benefit obligations to their employees, including their retirement obligations and Supplemental Executive Retirement Plans ("SERPs"). Since BankRI and First Ipswich are the primary beneficiaries of their respective insurance policies, increases in the cash value of the policies, as well as insurance proceeds received, are recorded in non-interest income and are not subject to income taxes. BOLI is recorded at the cash value of the policies, less any applicable cash surrender charges, and is reflected as an asset in the accompanying consolidated balance sheets. Cash proceeds, if any, are classified as cash flows from investing activities. The Company reviews the financial strength of the insurance carriers prior to the purchase of BOLI to ensure minimum credit ratings of at least investment grade. The financial strength of the carriers is reviewed at least annually, and BOLI with any individual carrier is limited to 10% of the Company's capital. Total BOLI is limited to 25% of the Company's capital.
Goodwill and Other Identified Intangible Assets	Goodwill and Other Identified Intangible Assets Goodwill represents the excess of the cost of an acquisition over the fair value of the net assets acquired. Goodwill and indefinite-lived identified intangible assets are not subject to amortization. Definite-lived identified intangible assets are assets resulting from acquisitions that are being amortized over their estimated useful lives. The recoverability of goodwill and identified intangible assets is evaluated for impairment at least annually. As part of this evaluation, the Company makes a qualitative assessment of whether it is more likely than not that the fair value of an acquired asset is greater than its carrying amount. If the Company qualitatively concludes that it is more likely than not that the fair value of an acquired asset is greater than its carrying amount, no further testing is necessary. If, however, the Company qualitatively concludes that the fair value of an acquired asset is less than its carrying value, the Company should recognize an impairment charge for the amount by which the carrying amount exceeds the fair value. The Company did not have any impairment of Goodwill and other identified intangible assets as of December 31, 2018 and 2017 .
OREO and Other Repossessed Assets	OREO and Other Repossessed Assets OREO and other repossessed assets consists of properties acquired through foreclosure, real estate acquired through acceptance of a deed in lieu of foreclosure and loans determined to be substantively repossessed. Real estate loans that are substantively repossessed include only those loans for which the Company has taken possession of the collateral. OREO and other repossessed assets which consist of vehicles and equipment, if any, are recorded initially at estimated fair value less costs to sell, resulting in a new cost basis. The amount by which the recorded investment in the loan exceeds the fair value (net of estimated cost to sell) of the foreclosed or repossessed asset is charged to the allowance for loan and lease losses. Such evaluations are based on an analysis of individual properties/assets as well as a general assessment of current real estate market conditions. Subsequent declines in the fair value of the foreclosed or repossessed asset below the new cost basis are recorded through the use of a valuation allowance. Subsequent increases in the fair value are recorded as reductions in the allowance, but not below zero. Rental revenue received on foreclosed or repossessed assets is included in other non-interest income, whereas operating expenses and changes in the valuation allowance relating to foreclosed and repossessed assets are included in other non-interest expense. Certain costs used to improve such properties are capitalized. Gains and losses from the sale of OREO and other repossessed assets are reflected in non-interest expense when realized. Together with nonperforming loans, OREO and repossessed assets comprise nonperforming assets.
Derivatives	Derivatives The Company utilizes loan level derivatives which consists of interest rate contracts (swaps, caps and floors), and risk participation agreements as part of the Company's interest-rate risk management strategy for certain assets and liabilities and not for speculative purposes. Based on the Company's intended use for the loan level derivatives at inception, the Company designates the derivative as either an economic hedge of an asset or liability, or a hedging instrument subject to the hedge accounting provisions of FASB ASC Topic 815, "Derivatives and Hedging." Loan level derivatives and foreign exchange contracts entered into on behalf of our customers are designated as economic hedges and are recorded at fair value within other assets or liabilities. Changes in the fair value of these non hedging derivatives are recorded directly through earnings at each reporting period.
Transfer of Financial Assets	Transfer of Financial Assets Transfers of financial assets are accounted for as sales when control over the assets has been surrendered. Control over transferred assets is deemed to be surrendered when (1) the assets have been isolated from the Company, (2) the transferee obtains the right (free of conditions that constrain it from taking advantage of that right) to pledge or exchange the transferred assets, and (3) the Company does not maintain effective control over the transferred assets through an agreement to repurchase them before their maturity.
Securities Sold under Agreements to Repurchase	Securities Sold under Agreements to Repurchase The Company enters into sales of securities under agreements to repurchase with the Banks' commercial customers. These agreements are treated as financings, and the obligations to repurchase securities sold are reflected as a liability in the consolidated balance sheets. Securities pledged as collateral under agreements to repurchase are reflected as assets in the accompanying consolidated balance sheets.
Employee Benefits	Employee Benefits Costs related to the Company's 401(k) plan are recognized in current earnings. Costs related to the Company's nonqualified deferred compensation plan, SERPs and postretirement benefits are recognized over the vesting period or the related service periods of the participating employees. Changes in the funded status of postretirement benefits are recognized through comprehensive income in the year in which changes occur. Compensation expense for the Company's Employee Stock Ownership Program ("ESOP") is recorded at an amount equal to the shares allocated by the ESOP multiplied by the average fair market value of the shares during the year. The Company recognizes compensation expense ratably over the year based upon the Company's estimate of the number of shares expected to be allocated by the ESOP. The difference between the average fair market value and the cost of the shares allocated by the ESOP is recorded as an adjustment to additional paid-in capital. The fair value of restricted stock awards and stock option grants are determined as of the grant date and are recorded as compensation expense over the period in which the shares of restricted stock awards and stock options vest. Forfeitures are accounted for as they occur.
Fair Value Measurements	Fair Value Measurements ASC 820-10, "Fair Value Measurements and Disclosures," defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. A fair value measurement assumes that the transaction to sell the asset or transfer the liability occurs in the principal market for the asset or liability or, in the absence of a principal market, the most advantageous market for the asset or liability. The price in the principal (or most advantageous) market used to measure the fair value of the asset or liability is not adjusted for transaction costs. An orderly transaction is a transaction that assumes exposure to the market for a period prior to the measurement date to allow for marketing activities that are usual and customary for transactions involving such assets and liabilities. It is not a forced transaction. Market participants are buyers and sellers in the principal market that are independent, knowledgeable, able to transact, and willing to transact. A fair-value hierarchy for valuation inputs that gives the highest priority to quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs are included in ASC 820. The fair value hierarchy is as follows: Level 1: Inputs are unadjusted quoted prices in active markets for assets and liabilities identical to those reported at fair value. Level 2: Inputs other than quoted prices included within Level 1. Level 2 inputs are observable either directly or indirectly. These inputs might include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (such as interest rates, volatilities, prepayment speeds, credit risks, etc.) or inputs that are derived principally from or corroborated by market data by correlation or other means. Level 3: Inputs are unobservable inputs for an asset or liability that reflect an entity's own assumptions about the assumptions that market participants would use in pricing the assets or liabilities. These inputs are used to determine fair value only when observable inputs are not available.
Earnings per Common Share	Earnings per Common Share Basic earnings per share ("EPS") is computed by dividing net income by the weighted average number of shares of common stock outstanding for the applicable period, exclusive of Treasury shares, unearned ESOP shares and unvested shares of restricted stock. Diluted EPS is calculated after adjusting the denominator of the basic EPS calculation for the effect of all potential dilutive common shares outstanding during the period. The dilutive effects of options and unvested restricted stock awards are computed using the "treasury stock" method. Management evaluated the "two class" method and concluded that the method did not apply to the Company's EPS calculation.
Income Taxes	Income Taxes Income taxes are accounted for under the asset and liability method. Under this method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. Tax positions that are more likely than not to be sustained upon a tax examination are recognized in the Company's financial statements to the extent that the benefit is greater than 50% likely of being recognized. Interest resulting from underpayment of income taxes is classified as income tax expense in the first period the interest would begin accruing according to the provision of the relevant tax law. Penalties resulting from underpayment of income taxes are classified as income tax expense in the period for which the Company claims or expects to claim an uncertain tax position or in the period in which the Company's judgment changes regarding an uncertain tax position.
Treasury Stock	Treasury Stock Any shares repurchased under the Company's share repurchase programs were purchased in open-market transactions and are held as treasury stock. Treasury stock also consists of common stock withheld to satisfy federal, state and local income tax withholding requirements for employee restricted stock awards upon vesting. All treasury stock is held at cost.
Segment Reporting	Segment Reporting An operating segment is defined as a component of a business for which separate financial information is available that is evaluated regularly by the chief operating decision-maker in deciding how to allocate resources and evaluate performance. The Company is a bank holding company with subsidiaries engaged in the business of banking and activities closely related to banking. The Company's banking business provided substantially all of its total revenues and pre-tax income in 2018 , 2017 and 2016 . Therefore, the Company has determined to be a single segment.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In December 2018, FASB issued ASU 2018-20 Leases (Topic 842), to update provisions to ASU 2016-02, Leases (Topic 842). The first revision is in relation to sales taxes and other similar taxes collected from lessees. The amendments in this update permit lessors, as an accounting policy election, to not evaluate whether certain sales taxes and other similar taxes are lessor costs or lessee costs. Instead, those lessors will account for those costs as if they are lessee costs. The second revision is in relation to certain lessor costs. Certain lessor costs require lessors to exclude from variable payments, and therefore revenue, lessor costs paid by lessees directly to third parties. The amendments also require lessors to account for costs excluded from the consideration of a contract that are paid by the lessor and reimbursed by the lessee as variable payments. The third revision in this update is related to recognizing variable payments for contracts with lease and non-lease components require lessors to allocate certain variable payments to the lease and non-lease components when the changes in facts and circumstances on which the variable payment is based occur. Management has determined that this ASU does apply as of December 31, 2018 . Management has assembled a project team that meets regularly to address the changes pursuant to Topic 842. The Company rents premises used in business operations under non-cancelable operating leases, which currently are not reflected in its consolidated balance sheet. As disclosed in Note 13, the Company was committed to $28.4 million of future minimum lease payments under these non-cancelable operating leases. Upon adoption of ASU 2016-02 on January 1, 2019, the Company expects to report increased assets and liabilities of approximately $23.6 million as a result of recognizing right of-use assets and lease liabilities in its consolidated balance sheets. The Company does not expect a material change to the timing of expense recognition in the consolidated statements of income. In November 2018, FASB issued ASU 2018-19 Codification Improvements to Topic 326 Financial Instruments - Credit Losses, to clarify the Codification or to correct unintended application of guidance within ASU 2016-13 Financial instruments - Credit Losses (Topic 326). This ASU is effective for the fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted. Management has determined that ASU 2018-19 does apply, but has not determined the impact, if any, as of December 31, 2018 . In preparation for the adoption in 2020 of this ASU, management formed a steering committee to oversee the adoption of ASU 2016-13. The steering committee, along with a project team, has developed an approach for implementation and has selected a third party software service provider. The project team is in the testing phase of the third party software. In October 2018, FASB issued ASU 2018-16, Derivatives and Hedging (Topic 815), to permit the OIS rate based on SOFR as a U.S. benchmark interest rate. Including the OIS rate based on SOFR as an eligible benchmark interest rate during the early stages of the marketplace transition will facilitate the LIBOR to SOFR transition and provide sufficient lead time for entities to prepare for changes to interest rate risk hedging strategies for both risk management and hedge accounting purposes. This ASU is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted in any interim period upon issuance of this update if an entity already has adopted Update ASU 2017-12. Management has determined that this ASU does apply and has not determined the impact, if any, as of December 31, 2018 . In August 2018, FASB issued ASU 2018-14, Compensation-Retirement Benefits-Defined Benefit Plans-General (Subtopic 715-20), to modify the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. This ASU is effective for fiscal years ending after December 15, 2020, for public business entities and for fiscal years ending after December 15, 2021, for all other entities. Early adoption is permitted. Management believes that this ASU does apply and has not determined the impact, if any, as of December 31, 2018 . In February 2016, FASB issued ASU 2016-02, Leases (“ASU 2016-02”). This ASU requires lessees to record most leases on their balance sheet but recognize expenses on their income statements in a manner similar to current accounting. This ASU also eliminates current real estate-specific provisions for all companies. For lessors, this ASU modifies the classification criteria and the accounting for sales-type and direct financing leases. Subsequently, in July 2018, FASB issued ASU 2018-10, Codification Improvements to Topic 842, Leases. This ASU was issued to clarify the Codification or to correct unintended application of guidance within ASU 2016-02. Also in July 2018, FASB issued ASU 2018-11, “Targeted Improvements” (“ASU 2018-11”), which allows for an optional transition method in which the provisions of Topic 842 would be applied upon the adoption date and would not have to be retroactively applied to the earliest reporting period presented in the consolidated financial statements. ASU 2016-02, 2018-10, and 2018-11 are all effective for fiscal years beginning after December 15, 2018, including interim periods therein. Early adoption is permitted. Management has determined that these ASUs do apply as of December 31, 2018 . Management has assembled a project team that meets regularly to address the changes pursuant to Topic 842. The Company rents premises used in business operations under non-cancelable operating leases, which currently are not reflected in its Consolidated Balance Sheet. As disclosed in Note 13, the Company was committed to $28.4 million of future minimum lease payments under these non-cancelable operating leases. Upon adoption of ASU 2016-02 on January 1, 2019, the Company expects to report increased assets and liabilities of approximately $23.6 million as a result of recognizing right of-use assets and lease liabilities in its consolidated balance sheets. The Company does not expect a material change to the timing of expense recognition in the consolidated statements of income. In August 2018, FASB issued ASU 2018-13, Fair Value Measurement (Topic 820), to modify the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement, based on the concepts in the Concepts Statement, including the consideration of costs and benefits. This ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. Early adoption is permitted. Management believes that this ASU does apply and has not determined the impact, if any, as of December 31, 2018 . In February 2018, FASB issued ASU 2018-03, Technical Corrections and Improvements to Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. This ASU was issued to add improvements to update ASU 2016-01 to increase stakeholders’ awareness of the amendments and to expedite the improvements. This ASU is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years beginning after June 15, 2018. Public business entities with fiscal years beginning between December 15, 2017 and June 15, 2018, are not required to adopt these amendments until the interim period beginning after June 15, 2018, and public business entities with fiscal years beginning between June 15, 2018, and December 15, 2018, are not required to adopt these amendments before adopting the amendments in Update 2016-01. Management has determined that ASU 2018-03 does apply and has determined the impact to be immaterial as of December 31, 2018 . In February 2018, the FASB issued Accounting Standards Update (ASU) No. 2018-02, "Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income" was issued to address a narrow-scope financial reporting issue that arose as a consequence of the change in the tax law. On December 22, 2017, the U.S. federal government enacted a tax bill, H.R.1, An Act to Provide for Reconciliation Pursuant to Titles II and V of the Concurrent Resolution on the Budget for Fiscal Year 2018 (the “Tax Reform Act”). The ASU No. 2018-02 requires a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the newly enacted federal corporate income tax rate. The amount of the reclassification would be the difference between the historical corporate income tax rate of 35 percent and the newly enacted 21 percent corporate income tax rate. The ASU No. 2018-02 is effective for all entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years with early adoption permitted, including adoption in any interim period, for (i) public business entities for reporting periods for which financial statements have not yet been issued and (ii) all other entities for reporting periods for which financial statements have not yet been made available for issuance. The changes are required to be applied retrospectively to each period (or periods) in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act of 2017 is recognized. Management early adopted this ASU as of December 31, 2017, which resulted in the reclassification from accumulated other comprehensive loss to retained earnings totaling $1.1 million , reflected in the Consolidated Statements of Changes in Stockholders' Equity. In November 2017, the FASB issued ASU 2017-14, Income Statement-Reporting Comprehensive Income (Topic 220), Revenue Recognition (Topic 605), and Revenue from Contracts with Customers (Topic 606): Amendments to SEC Paragraphs Pursuant to Staff Accounting Bulletin No. 116 and SEC Release No. 33-10403. This ASU was issued to amend certain SEC paragraphs pursuant to the SEC Staff Accounting Bulletin No.116 and SEC Release No. 33-10403, which bring existing guidance into conformity with Topic 606, Revenue from Contract with Customers. The ASU was effective for annual periods beginning after December 15, 2017. Management has adopted this ASU as of January 1, 2018 and has determined the impact to be immaterial. In May 2017, the FASB issued ASU 2017-09, Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting. FASB issued this Update to address the diversity in practice as well as the cost and complexity when applying the guidance in Topic 718, Compensation - Stock Compensation, to a change to the terms or conditions of a share-based payment award. For public entities, this ASU is effective for annual reporting periods beginning after December 15, 2017. Management adopted this ASU as of January 1, 2018 and has determined the impact to be immaterial. In March 2017, the FASB issued Accounting Standards Update ASU 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost (Topic 715). This ASU was issued primarily to improve the presentation of net periodic pension cost and net periodic postretirement benefit cost. This ASU is effective for annual reporting periods beginning after December 15, 2017. Management adopted this ASU as of January 1, 2018 and has determined the impact to be immaterial. In January 2017, the FASB issued ASU 2017-04, Intangibles - Goodwill and Other (Topic 350). This ASU was issued to simplify the subsequent measurement of goodwill by eliminating Step 2 from the goodwill impairment test. For public entities, this ASU is effective for the fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted and application should be on a prospective basis. Management has evaluated this ASU and as of December 31, 2017, the Company has adopted the ASU and determined the impact to be immaterial. In June 2016, the FASB issued ASU 2016-13, Financial instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The intent of this ASU is to replace the current GAAP method of calculating credit losses. Current GAAP uses a higher threshold at which likely losses can be calculated and recorded. The new process will require institutions to account for likely losses that originally would not have been part of the calculation. The calculation will incorporate future forecasting in addition to historical and current measures. For public entities that file with the SEC, this ASU is effective for the fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. This ASU must be applied prospectively to debt securities marked as other than temporarily impaired. A retrospective approach will be applied cumulatively to retained earnings. Early adoption is permitted as of the fiscal years beginning after December 15, 2018. Management has determined that ASU 2016-13 does apply, but has not determined the impact, if any, as of December 31, 2018 . In preparation for the adoption in 2020 of this ASU, management formed a steering committee to oversee the adoption of ASU 2016-13. The steering committee, along with a project team, has developed an approach for implementation and has selected a third party software service provider. The project team is in the testing phase of the third party software. In January 2016, the FASB issued ASU 2016-01, Financial Instruments. This ASU significantly revises an entity’s accounting related to (1) the classification and measurement of investments in equity securities and (2) the presentation of certain fair value changes for financial liabilities measured at fair value. It also amends certain disclosure requirements associated with the fair value of financial instruments. This ASU is effective for fiscal years beginning after December 15, 2017, including interim periods therein. Management adopted ASU 2016-01 as of January 1, 2018 and management has determined the impact to be immaterial. Accounting Standards Update No. 2014-09, “Revenue from Contracts with Customers” (“ASU 2014-09”), was issued in May 2014 and provides a revenue recognition framework for any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of non-financial assets unless those contracts are within the scope of other accounting standards. As issued, ASU 2014-09 was effective for annual periods beginning after December 15, 2016, including interim periods within that reporting period with early adoption not permitted. The standard permits the use of either the retrospective or cumulative effect transition method. In August 2015, Accounting Standards Update No. 2015-14, “Deferral of the Effective Date” (“ASU 2015-14”) was issued and delayed the effective date of ASU 2014-09 to annual and interim periods in fiscal years beginning after December 15, 2017. In 2016, Accounting Standards Update No. 2016-08, “Principal versus Agent Considerations” (“ASU 2016-08”), Accounting Standards Update No. 2016-10, “Identifying Performance Obligations and Licensing” (“ASU 2016-10”) and Accounting Standards Update No. 2016-12, “Narrow-Scope Improvements and Practical Expedients” (“ASU 2016-12”) were issued. These ASUs did not change the core principle for revenue recognition in Topic 606; instead, the amendments provided more detailed guidance in a few areas and additional implementation guidance and examples to reduce the degree of judgment necessary to comply with Topic 606. The effective date and transition requirements for ASU 2016-08, ASU 2016-10 and ASU 2016-12 were the same as those provided by ASU 2015-14. Management assembled a project team to address the changes pursuant to Topic 606. The project team completed a scope assessment and contract review for in-scope revenue streams. Topic 606 did not apply to several income generating streams. Management excluded from their analysis, income associated with financial instruments, gains on sale of investment securities and loans, gains on Low Income Housing Tax Credits ("LIHTC") and loan level derivative income. Revenue streams that were included were service charges on deposit accounts, loan fees, and income received through a third party relationship. Management adopted the provisions of ASU 2014-09 effective January 1, 2018, using the modified retrospective transition method. The adoption did not have a material impact on the Company's consolidated financial statements. See Note 24, "Revenue from Contracts with Customers," for further details.

Acquisitions (Tables)

Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Schedule of estimated fair value of the 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: Net Assets Acquired at Fair Value (In Thousands) ASSETS Cash $ 42,995 Restricted stock 1,884 Loans 262,304 Premises and equipment 583 Goodwill 22,537 Core deposit and other intangibles 2,122 Other assets 2,595 Total assets acquired 335,020 LIABILITIES Deposits 273,701 Borrowings 5,000 Other liabilities 287 Total liabilities assumed 278,988 Purchase price $ 56,032

Cash and Short-Term Investments

Cash and Short-Term Investments (Tables)	12 Months Ended
	Dec. 31, 2018
Cash and Cash Equivalents [Abstract]
Short-term investments	Short-term investments are summarized as follows: At December 31, 2018 2017 (In Thousands) FRB interest bearing reserve $ 34,914 $ 28,263 FHLB overnight deposits 4,628 4,676 Federal funds sold 2,500 2,444 Total short-term investments $ 42,042 $ 35,383

Investment Securities (Tables)

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Schedule of securities available-for-sale securities	The following tables set forth investment securities available-for-sale, held-to-maturity and equity securities held-for-trading at the dates indicated: At December 31, 2018 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value (In Thousands) Investment securities available-for-sale: Debt securities: GSE debentures $ 184,072 $ 99 $ 3,092 $ 181,079 GSE CMOs 107,363 17 4,250 103,130 GSE MBSs 169,334 124 4,369 165,089 SBA commercial loan asset-backed securities 51 — — 51 Corporate debt obligations 40,618 — 910 39,708 U.S. treasury bonds 13,812 65 141 13,736 Total investment securities available-for-sale $ 515,250 $ 305 $ 12,762 $ 502,793 Investment securities held-to-maturity: GSE debentures $ 50,546 $ 22 $ 967 $ 49,601 GSEs MBSs 11,426 — 295 11,131 Municipal obligations 52,304 10 716 51,598 Foreign government obligations 500 — — 500 Total investment securities held-to-maturity $ 114,776 $ 32 $ 1,978 $ 112,830 Equity securities held-for-trading $ 4,207 $ — $ — $ 4,207 At December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value (In Thousands) Investment securities available-for-sale: Debt securities: GSE debentures $ 151,483 $ 70 $ 1,629 $ 149,924 GSE CMOs 131,082 27 4,087 127,022 GSE MBSs 191,281 354 2,322 189,313 SBA commercial loan asset-backed securities 73 — 1 72 Corporate debt obligations 62,811 110 238 62,683 U.S. treasury bonds 8,785 7 62 8,730 Trust preferred securities 1,471 — 73 1,398 Total debt securities 546,986 568 8,412 539,142 Marketable equity securities 978 13 9 982 Total investment securities available-for-sale $ 547,964 $ 581 $ 8,421 $ 540,124 Investment securities held-to-maturity: GSE debentures $ 41,612 $ — $ 811 $ 40,801 GSEs MBSs 13,923 — 218 13,705 Municipal obligations 53,695 159 337 53,517 Foreign government obligations 500 — — 500 Total investment securities held-to-maturity $ 109,730 $ 159 $ 1,366 $ 108,523
Investment securities in a continuous unrealized loss position	Investment securities as of December 31, 2018 and 2017 that have been in a continuous unrealized loss position for less than twelve months or twelve months or longer are as follows: At December 31, 2018 Less than Twelve Months Twelve Months or Longer Total Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses (In Thousands) Investment securities available-for-sale: GSE debentures $ 25,780 $ 191 $ 130,284 $ 2,901 $ 156,064 $ 3,092 GSE CMOs — — 102,630 4,250 102,630 4,250 GSE MBSs 21,487 113 138,051 4,256 159,538 4,369 SBA commercial loan asset-backed securities — — 51 — 51 — Corporate debt obligations 10,019 93 29,689 817 39,708 910 U.S. Treasury bonds 3,927 37 4,753 104 8,680 141 Temporarily impaired investment securities available-for-sale 61,213 434 405,458 12,328 466,671 12,762 Investment securities held-to-maturity: GSE debentures — — 40,653 967 40,653 967 GSEs MBSs — — 11,080 295 11,080 295 Municipal obligations 14,813 107 35,058 609 49,871 716 Foreign government obligations — — 500 — 500 — Temporarily impaired investment securities held-to-maturity 14,813 107 87,291 1,871 102,104 1,978 Total temporarily impaired investment securities $ 76,026 $ 541 $ 492,749 $ 14,199 $ 568,775 $ 14,740 At December 31, 2017 Less than Twelve Months Twelve Months or Longer Total Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses (In Thousands) Investment securities available-for-sale: GSE debentures $ 120,409 $ 1,263 $ 12,481 $ 366 $ 132,890 $ 1,629 GSE CMOs 2,862 34 123,548 4,053 126,410 4,087 GSE MBSs 94,985 753 74,782 1,569 169,767 2,322 SBA commercial loan asset-backed securities 34 — 33 1 67 1 Corporate debt obligations 30,978 154 2,423 84 33,401 238 U.S. Treasury bonds 4,767 62 — — 4,767 62 Trust preferred securities — — 1,398 73 1,398 73 Marketable equity securities — — 503 9 503 9 Temporarily impaired investment securities available-for-sale 254,035 2,266 215,168 6,155 469,203 8,421 Investment securities held-to-maturity: GSE debentures 26,594 281 14,208 530 40,802 811 GSEs MBSs 1,996 15 11,674 203 13,670 218 Municipal obligations 30,542 235 7,408 102 37,950 337 Foreign government obligations — — 500 — 500 — Temporarily impaired investment securities held-to-maturity 59,132 531 33,790 835 92,922 1,366 Total temporarily impaired investment securities $ 313,167 $ 2,797 $ 248,958 $ 6,990 $ 562,125 $ 9,787
Schedule of maturities of the investments in debt securities	The final stated maturities of the debt securities are as follows for the periods indicated: At December 31, 2018 2017 Amortized Cost Estimated Fair Value Weighted Average Rate Amortized Cost Estimated Fair Value Weighted Average Rate (Dollars in Thousands) Investment securities available-for-sale: Within 1 year $ 12,041 $ 12,007 2.03% $ 23,612 $ 23,652 2.27% After 1 year through 5 years 195,701 192,692 2.14% 142,772 142,029 2.05% After 5 years through 10 years 115,665 112,819 2.18% 136,746 134,978 2.06% Over 10 years 191,843 185,275 2.17% 243,856 238,483 2.06% $ 515,250 $ 502,793 2.16% $ 546,986 $ 539,142 2.07% Investment securities held-to-maturity: Within 1 year $ 7,640 $ 7,618 1.17% $ 918 $ 916 0.78% After 1 year through 5 years 72,735 71,492 1.84% 58,335 57,939 1.74% After 5 years through 10 years 23,025 22,640 2.20% 36,589 35,998 1.79% Over 10 years 11,376 11,080 2.13% 13,888 13,670 1.98% $ 114,776 $ 112,830 1.89% $ 109,730 $ 108,523 1.78%
Schedule of sales of investment securities	Sales of investment and restricted equity securities are summarized as follows: Year Ended December 31, 2018 2017 (In Thousands) Proceeds from sales of debt securities $ 20,000 $ — Proceeds from sales of marketable and restricted equity securities 2,700 11,393 Gross gains from sales 1,472 $ 11,612 Gross losses from sales (68 ) (219 ) Gain on sales of securities, net $ 1,404 $ 11,393

Restricted Equity Securities (T

Restricted Equity Securities (Tables)	12 Months Ended
	Dec. 31, 2018
Restricted Investments Note [Abstract]
Components of investments in the restricted equity securities of various entities	Investments in the restricted equity securities of various entities are as follows: At December 31, 2018 2017 (In Thousands) FHLBB stock $ 43,655 $ 42,427 FRB stock 17,995 16,842 Other restricted equity securities 101 100 $ 61,751 $ 59,369

Loans and Leases (Tables)

Loans and Leases (Tables)	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Summary of loan and lease balances for the originated and acquired portfolios	The following tables present loan and lease balances and weighted average coupon rates for the originated and acquired loan and lease portfolios at the dates indicated: At December 31, 2018 Originated Acquired Total Balance Weighted Average Coupon Balance Weighted Average Coupon Balance Weighted Average Coupon (Dollars In Thousands) Commercial real estate loans: Commercial real estate $ 2,208,904 4.61 % $ 121,821 4.62 % $ 2,330,725 4.61 % Multi-family mortgage 799,813 4.51 % 47,898 4.58 % 847,711 4.51 % Construction 151,138 5.62 % 22,162 6.74 % 173,300 5.76 % Total commercial real estate loans 3,159,855 4.63 % 191,881 4.85 % 3,351,736 4.64 % Commercial loans and leases: Commercial 712,630 4.96 % 23,788 5.39 % 736,418 4.97 % Equipment financing 978,840 7.61 % 3,249 5.97 % 982,089 7.60 % Condominium association 50,451 4.70 % — — % 50,451 4.70 % Total commercial loans and leases 1,741,921 6.44 % 27,037 5.46 % 1,768,958 6.43 % Consumer loans: Residential mortgage 653,059 4.09 % 129,909 4.45 % 782,968 4.15 % Home equity 331,014 5.05 % 45,470 5.39 % 376,484 5.09 % Other consumer 23,260 5.55 % 110 17.81 % 23,370 5.61 % Total consumer loans 1,007,333 4.44 % 175,489 4.70 % 1,182,822 4.48 % Total loans and leases $ 5,909,109 5.13 % $ 394,407 4.83 % $ 6,303,516 5.11 % At December 31, 2017 Originated Acquired Total Balance Weighted Average Coupon Balance Weighted Average Coupon Balance Weighted Average Coupon (Dollars In Thousands) Commercial real estate loans: Commercial real estate $ 2,069,392 4.17 % $ 105,577 4.37 % $ 2,174,969 4.18 % Multi-family mortgage 735,921 4.09 % 24,749 4.48 % 760,670 4.10 % Construction 140,138 4.58 % — — % 140,138 4.58 % Total commercial real estate loans 2,945,451 4.17 % 130,326 4.39 % 3,075,777 4.18 % Commercial loans and leases: Commercial 696,825 4.35 % 8,179 5.77 % 705,004 4.37 % Equipment financing 861,974 7.28 % 4,514 5.92 % 866,488 7.27 % Condominium association 52,619 4.49 % — — % 52,619 4.49 % Total commercial loans and leases 1,611,418 5.92 % 12,693 5.82 % 1,624,111 5.92 % Consumer loans: Residential mortgage 604,897 3.81 % 55,168 4.28 % 660,065 3.85 % Home equity 314,189 4.16 % 41,765 4.62 % 355,954 4.21 % Other consumer 14,667 5.51 % 105 18.00 % 14,772 5.60 % Total consumer loans 933,753 3.95 % 97,038 4.44 % 1,030,791 4.00 % Total loans and leases $ 5,490,622 4.65 % $ 240,057 4.49 % $ 5,730,679 4.64 %
Schedule of activity in the accretable yield for acquired loan portfolio	The following table summarizes activity in the accretable yield for the acquired loan portfolio for the periods indicated: Year Ended December 31, 2018 2017 2016 (In Thousands) Balance at beginning of year $ 10,522 $ 14,353 $ 20,796 Accretion (4,117 ) (7,801 ) (6,781 ) Reclassification from nonaccretable difference as a result from changes in expected cash flows 1,500 3,970 338 Balance at end of year $ 7,905 $ 10,522 $ 14,353
Summary of the change in the total amounts of loans and advances, all of which were performing, to directors, executive officers and their affiliates	The following table summarizes the change in the total amounts of loans and advances, to directors, executive officers and their affiliates for the periods indicated. All loans were performing as of December 31, 2018 . Year Ended December 31, 2018 2017 (In Thousands) Balance at beginning of year $ 47,941 $ 43,458 New loans granted during the year 2,842 13,554 Advances on lines of credit 193 473 Repayments (4,205 ) (9,544 ) Balance at end of year $ 46,771 $ 47,941

Allowance for Loan and Lease _2

Allowance for Loan and Lease Losses (Tables)	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Schedule of changes in the allowance for loan and lease losses	The following tables present the changes in the allowance for loan and lease losses and the recorded investment in loans and leases by portfolio segment for the periods indicated: Year Ended December 31, 2018 Commercial Real Estate Commercial Consumer Total (In Thousands) Balance at December 31, 2017 $ 27,112 $ 26,333 $ 5,147 $ 58,592 Charge-offs (103 ) (6,585 ) (540 ) (7,228 ) Recoveries — 2,287 290 2,577 Provision for loan and lease losses 1,178 3,248 325 4,751 Balance at December 31, 2018 $ 28,187 $ 25,283 $ 5,222 $ 58,692 Year Ended December 31, 2017 Commercial Real Estate Commercial Consumer Total (In Thousands) Balance at December 31, 2016 $ 27,645 $ 20,906 $ 5,115 $ 53,666 Charge-offs (494 ) (14,914 ) (403 ) (15,811 ) Recoveries 476 1,158 319 1,953 (Credit) provision for loan and lease losses (515 ) 19,183 116 18,784 Balance at December 31, 2017 $ 27,112 $ 26,333 $ 5,147 $ 58,592 Year Ended December 31, 2016 Commercial Real Estate Commercial Consumer Total (In Thousands) Balance at December 31, 2015 $ 30,151 $ 22,018 $ 4,570 $ 56,739 Charge-offs (2,169 ) (10,516 ) (1,982 ) (14,667 ) Recoveries — 642 750 1,392 Provision (credit) for loan and lease losses (337 ) 8,762 1,777 10,202 Balance at December 31, 2016 $ 27,645 $ 20,906 $ 5,115 $ 53,666
Provisions for credit losses	The provisions for credit losses are set forth below for the periods indicated: Originated Acquired Total Year Ended December 31, Year Ended December 31, Year Ended December 31, 2018 2017 2016 2018 2017 2016 2018 2017 2016 (In Thousands) Provision (credit) for loan and lease losses: Commercial real estate $ 254 $ (343 ) $ (750 ) $ 924 $ (172 ) $ 413 $ 1,178 $ (515 ) $ (337 ) Commercial 3,699 18,899 8,469 (451 ) 284 293 3,248 19,183 8,762 Consumer 556 273 1,263 (231 ) (157 ) 514 325 116 1,777 Total provision for loan and lease losses 4,509 18,829 8,982 242 (45 ) 1,220 4,751 18,784 10,202 Unfunded credit commitments 200 204 151 — — — 200 204 151 Total provision (credit) for credit losses $ 4,709 $ 19,033 $ 9,133 $ 242 $ (45 ) $ 1,220 $ 4,951 $ 18,988 $ 10,353
Summary of the recorded investments by credit quality indicator, by loan class	The following tables present the recorded investment in loans in each class as of December 31, 2018 by credit quality indicator. At December 31, 2018 Commercial Real Estate Multi- Family Mortgage Construction Commercial Equipment Financing Condominium Association Other Consumer Total (In Thousands) Originated: Loan rating: Pass $ 2,198,377 $ 799,483 $ 150,742 $ 685,773 $ 969,275 $ 50,186 $ 23,249 $ 4,877,085 OAEM 6,096 — — 3,726 52 — — 9,874 Substandard 4,431 330 396 22,870 6,895 265 11 35,198 Doubtful — — — 261 2,618 — — 2,879 Total originated 2,208,904 799,813 151,138 712,630 978,840 50,451 23,260 4,925,036 Acquired: Loan rating: Pass 111,919 47,715 22,162 23,250 3,240 — 110 208,396 OAEM 626 — — 236 — — — 862 Substandard 9,276 183 — 302 9 — — 9,770 Total acquired 121,821 47,898 22,162 23,788 3,249 — 110 219,028 Total loans $ 2,330,725 $ 847,711 $ 173,300 $ 736,418 $ 982,089 $ 50,451 $ 23,370 $ 5,144,064 As of December 31, 2018 , there were no loans categorized as definite loss. At December 31, 2018 Residential Mortgage Home Equity ($ In Thousands) Originated: Loan-to-value ratio: Less than 50% $ 171,523 21.9 % $ 142,534 37.9 % 50% - 69% 287,337 36.7 % 84,423 22.4 % 70% - 79% 173,870 22.2 % 73,898 19.6 % 80% and over 19,030 2.4 % 30,129 8.0 % Data not available* 1,299 0.2 % 30 — % Total originated 653,059 83.4 % 331,014 87.9 % Acquired: Loan-to-value ratio: Less than 50% 36,752 4.6 % 24,705 6.6 % 50%—69% 53,788 6.9 % 10,353 2.7 % 70%—79% 26,510 3.4 % 1,000 0.3 % 80% and over 6,701 0.9 % 4,348 1.2 % Data not available* 6,158 0.8 % 5,064 1.3 % Total acquired 129,909 16.6 % 45,470 12.1 % Total loans $ 782,968 100.0 % $ 376,484 100.0 % _______________________________________________________________________________ * Represents accounts for which data are not available. The following tables present the recorded investment in loans in each class as of December 31, 2017 by credit quality indicator. At December 31, 2017 Commercial Real Estate Multi- Family Mortgage Construction Commercial Equipment Financing Condominium Association Other Consumer Total (In Thousands) Originated: Loan rating: Pass $ 2,054,376 $ 735,313 $ 139,278 $ 670,265 $ 850,006 $ 52,619 $ 14,628 $ 4,516,485 OAEM 8,889 — — 7,691 3,630 — — 20,210 Substandard 5,926 608 860 17,681 5,012 — 39 30,126 Doubtful 201 — — 1,188 3,326 — — 4,715 Total originated 2,069,392 735,921 140,138 696,825 861,974 52,619 14,667 4,571,536 Acquired: Loan rating: Pass 94,244 24,459 — 6,643 4,501 — 104 129,951 OAEM 9,839 — — 265 — — 1 10,105 Substandard 1,494 290 — 1,271 13 — — 3,068 Total acquired 105,577 24,749 — 8,179 4,514 — 105 143,124 Total loans $ 2,174,969 $ 760,670 $ 140,138 $ 705,004 $ 866,488 $ 52,619 $ 14,772 $ 4,714,660 As of December 31, 2017 , there were no loans categorized as definite loss. At December 31, 2017 Residential Mortgage Home Equity ($ In Thousands) Originated: Loan-to-value ratio: Less than 50% $ 153,373 23.2 % $ 148,137 41.6 % 50%—69% 265,328 40.2 % 75,099 21.1 % 70%—79% 168,272 25.5 % 63,742 17.9 % 80% and over 16,547 2.5 % 27,122 7.6 % Data not available* 1,377 0.2 % 89 — % Total originated 604,897 91.6 % 314,189 88.2 % Acquired: Loan-to-value ratio: Less than 50% 16,521 2.5 % 25,312 7.1 % 50%—69% 19,182 2.9 % 13,883 3.9 % 70%—79% 10,507 1.6 % 943 0.3 % 80% and over 7,893 1.2 % 582 0.2 % Data not available* 1,065 0.2 % 1,045 0.3 % Total acquired 55,168 8.4 % 41,765 11.8 % Total loans $ 660,065 100.0 % $ 355,954 100.0 % _______________________________________________________________________________ * Represents accounts for which data are not available.
Information regarding troubled debt restructuring loans	The following table presents information regarding foreclosed residential real estate property for the periods indicated: At December 31, 2018 At December 31, 2017 (In Thousands) Recorded investment in mortgage loans collateralized by residential real estate property that are in the process of foreclosure $ 121 $ 633 The following table sets forth information regarding troubled debt restructured loans and leases at the dates indicated: At December 31, 2018 At December 31, 2017 (In Thousands) Troubled debt restructurings: On accrual $ 12,257 $ 16,241 On nonaccrual 8,684 9,770 Total troubled debt restructurings $ 20,941 $ 26,011
Information regarding the aging of past due loans, by loan class	The following tables present an age analysis of the recorded investment in total loans and leases as of December 31, 2018 and 2017 . At December 31, 2018 Past Due Loans and Leases Past Due Greater Than 90 Days and Accruing 31-60 Days 61-90 Days Greater Than 90 Days Total Current Total Loans and Leases Nonaccrual Loans and Leases (In Thousands) Originated: Commercial real estate loans: Commercial real estate $ 5,139 $ 896 $ 2,962 $ 8,997 $ 2,199,907 $ 2,208,904 $ 277 $ 3,806 Multi-family mortgage 893 — 145 1,038 798,775 799,813 — 330 Construction 297 — 396 693 150,445 151,138 — 396 Total commercial real estate loans 6,329 896 3,503 10,728 3,149,127 3,159,855 277 4,532 Commercial loans and leases: Commercial 2,021 582 6,244 8,847 703,783 712,630 1,962 6,421 Equipment financing 2,509 650 5,685 8,844 969,996 978,840 12 9,500 Condominium association 320 — — 320 50,131 50,451 — 265 Total commercial loans and leases 4,850 1,232 11,929 18,011 1,723,910 1,741,921 1,974 16,186 Consumer loans: Residential mortgage 400 — 1,597 1,997 651,062 653,059 — 1,842 Home equity 761 25 183 969 330,045 331,014 1 191 Other consumer 51 18 15 84 23,176 23,260 — 17 Total consumer loans 1,212 43 1,795 3,050 1,004,283 1,007,333 1 2,050 Total originated loans and leases $ 12,391 $ 2,171 $ 17,227 $ 31,789 $ 5,877,320 $ 5,909,109 $ 2,252 $ 22,768 (Continued) At December 31, 2018 Past Due Loans and Leases Past Due Greater Than 90 Days and Accruing 31-60 Days 61-90 Days Greater Than 90 Days Total Current Total Loans and Leases Nonaccrual Loans and Leases (In Thousands) Acquired: Commercial real estate loans: Commercial real estate $ — $ 215 $ 9,087 $ 9,302 $ 112,519 $ 121,821 $ 9,018 $ 122 Multi-family mortgage 348 — — 348 47,550 47,898 — — Construction 360 242 — 602 21,560 22,162 — — Total commercial real estate loans 708 457 9,087 10,252 181,629 191,881 9,018 122 Commercial loans and leases: Commercial 124 44 290 458 23,330 23,788 90 200 Equipment financing — — 9 9 3,240 3,249 9 — Total commercial loans and leases 124 44 299 467 26,570 27,037 99 200 Consumer loans: Residential mortgage — 371 2,113 2,484 127,425 129,909 2,113 290 Home equity 191 265 2 458 45,012 45,470 — 717 Other consumer — — — — 110 110 — — Total consumer loans 191 636 2,115 2,942 172,547 175,489 2,113 1,007 Total acquired loans and leases 1,023 1,137 11,501 13,661 380,746 394,407 11,230 1,329 Total loans and leases $ 13,414 $ 3,308 $ 28,728 $ 45,450 $ 6,258,066 $ 6,303,516 $ 13,482 $ 24,097 At December 31, 2017 Past Due Loans and Leases Past Due Greater Than 90 Days and Accruing 31-60 Days 61-90 Days Greater Than 90 Days Total Current Total Loans and Leases Nonaccrual Loans and Leases (In Thousands) Originated: Commercial real estate loans: Commercial real estate $ 3,294 $ 391 $ 1,843 $ 5,528 $ 2,063,864 $ 2,069,392 $ — $ 3,182 Multi-family mortgage 6,141 2,590 — 8,731 727,190 735,921 — 608 Construction 6,537 330 860 7,727 132,411 140,138 — 860 Total commercial real estate loans 15,972 3,311 2,703 21,986 2,923,465 2,945,451 — 4,650 Commercial loans and leases: Commercial 1,344 597 7,724 9,665 687,160 696,825 — 10,365 Equipment financing 3,214 2,494 3,203 8,911 853,063 861,974 224 8,106 Condominium association 857 262 — 1,119 51,500 52,619 — — Total commercial loans and leases 5,415 3,353 10,927 19,695 1,591,723 1,611,418 224 18,471 Consumer loans: Residential mortgage 1,256 166 728 2,150 602,747 604,897 — 1,979 Home equity 643 19 32 694 313,495 314,189 1 132 Other consumer 238 20 28 286 14,381 14,667 — 43 Total consumer loans 2,137 205 788 3,130 930,623 933,753 1 2,154 Total originated loans and leases $ 23,524 $ 6,869 $ 14,418 $ 44,811 $ 5,445,811 $ 5,490,622 $ 225 $ 25,275 (Continued) At December 31, 2017 Past Due Loans and Leases Past Due Greater Than 90 Days and Accruing 31-60 Days 61-90 Days Greater Than 90 Days Total Current Total Loans and Leases Nonaccrual Loans and Leases (In Thousands) Acquired: Commercial real estate loans: Commercial real estate $ 1,008 $ — $ 656 $ 1,664 $ 103,913 $ 105,577 $ 586 $ 131 Multi-family mortgage — — 3 3 24,746 24,749 3 — Total commercial real estate loans 1,008 — 659 1,667 128,659 130,326 589 131 Commercial loans and leases: Commercial — 44 1,022 1,066 7,113 8,179 17 1,254 Equipment financing — — 13 13 4,501 4,514 13 — Total commercial loans and leases — 44 1,035 1,079 11,614 12,693 30 1,254 Consumer loans: Residential mortgage — 463 1,990 2,453 52,715 55,168 1,990 — Home equity 508 — 186 694 41,071 41,765 186 612 Other consumer — — — — 105 105 — — Total consumer loans 508 463 2,176 3,147 93,891 97,038 2,176 612 Total acquired loans and leases 1,516 507 3,870 5,893 234,164 240,057 2,795 1,997 Total loans and leases $ 25,040 $ 7,376 $ 18,288 $ 50,704 $ 5,679,975 $ 5,730,679 $ 3,020 $ 27,272
Impaired loans and leases, by loan and leases class	The following tables include the recorded investment and unpaid principal balances of impaired loans and leases with the related allowance amount, if applicable, for the originated and acquired loan and lease portfolios at the dates indicated. Also presented are the average recorded investments in the impaired loans and leases and the related amount of interest recognized during the period that the impaired loans were impaired. At December 31, 2018 At December 31, 2017 Recorded (1) Unpaid Related Recorded Investment (2) Unpaid Related (In Thousands) Originated: With no related allowance recorded: Commercial real estate $ 5,569 $ 5,545 $ — $ 9,978 $ 9,962 $ — Commercial 30,927 31,053 — 24,906 25,040 — Consumer 2,989 2,978 — 3,508 3,500 — Total originated with no related allowance recorded 39,485 39,576 — 38,392 38,502 — With an allowance recorded: Commercial real estate 396 396 5 3,056 3,056 — Commercial 8,224 8,208 2,961 8,912 8,862 3,105 Consumer 665 664 89 — — — Total originated with an allowance recorded 9,285 9,268 3,055 11,968 11,918 3,105 Total originated impaired loans and leases 48,770 48,844 3,055 50,360 50,420 3,105 Acquired: With no related allowance recorded: Commercial real estate 9,538 9,538 — 1,880 1,880 — Commercial 531 531 — 1,594 1,594 — Consumer 4,772 4,772 — 4,736 4,736 — Total acquired with no related allowance recorded 14,841 14,841 — 8,210 8,210 — With an allowance recorded: Consumer 154 154 26 115 115 22 Total acquired with an allowance recorded 154 154 26 115 115 22 Total acquired impaired loans and leases 14,995 14,995 26 8,325 8,325 22 Total impaired loans and leases $ 63,765 $ 63,839 $ 3,081 $ 58,685 $ 58,745 $ 3,127 __________________________________________________________________________ (1) Includes originated and acquired nonaccrual loans of $22.7 million and $1.3 million , respectively as of December 31, 2018 . (2) Includes originated and acquired nonaccrual loans of $24.9 million and $2.0 million , respectively as of December 31, 2017 . Year Ended December 31, 2018 December 31, 2017 December 31, 2016 Average Interest Average Interest Average Interest (In Thousands) Originated: With no related allowance recorded: Commercial real estate $ 6,484 $ 87 $ 10,181 $ 277 $ 6,608 $ 152 Commercial 26,514 993 24,950 747 23,445 600 Consumer 2,801 54 4,330 58 4,126 76 Total originated with no related allowance recorded 35,799 1,134 39,461 1,082 34,179 828 With an allowance recorded: Commercial real estate 99 — 3,271 162 4,715 195 Commercial 9,026 96 18,382 1 9,915 6 Consumer 835 11 — — 124 — Total originated with an allowance recorded 9,960 107 21,653 163 14,754 201 Total originated impaired loans and leases 45,759 1,241 61,114 1,245 48,933 1,029 Acquired: With no related allowance recorded: Commercial real estate 9,868 7 4,005 55 8,906 151 Commercial 1,212 16 2,280 31 4,255 75 Consumer 5,061 61 5,295 69 7,537 68 Total acquired with no related allowance recorded 16,141 84 11,580 155 20,698 294 With an allowance recorded: Commercial real estate — — — — 1,093 — Commercial — — — — 364 — Consumer 135 4 151 4 431 8 Total acquired with an allowance recorded 135 4 151 4 1,888 8 Total acquired impaired loans and leases 16,276 88 11,731 159 22,586 302 Total impaired loans and leases $ 62,035 $ 1,329 $ 72,845 $ 1,404 $ 71,519 $ 1,331
Schedule of the impaired and non-impaired loans and leases, by loan and leases class	The following tables present information regarding impaired and non-impaired loans and leases at the dates indicated: At December 31, 2018 Commercial Real Estate Commercial Consumer Total (In Thousands) Allowance for Loan and Lease Losses: Originated: Individually evaluated for impairment $ 5 $ 2,961 $ 89 $ 3,055 Collectively evaluated for impairment 26,617 22,131 5,075 53,823 Total originated loans and leases 26,622 25,092 5,164 56,878 Acquired: Individually evaluated for impairment — — 26 26 Collectively evaluated for impairment 32 83 20 135 Acquired with deteriorated credit quality 1,533 108 12 1,653 Total acquired loans and leases 1,565 191 58 1,814 Total allowance for loan and lease losses $ 28,187 $ 25,283 $ 5,222 $ 58,692 Loans and Leases: Originated: Individually evaluated for impairment $ 5,610 $ 32,127 $ 3,502 $ 41,239 Collectively evaluated for impairment 3,154,245 1,709,794 1,003,831 5,867,870 Total originated loans and leases 3,159,855 1,741,921 1,007,333 5,909,109 Acquired: Individually evaluated for impairment — 404 2,072 2,476 Collectively evaluated for impairment 121,119 24,094 142,194 287,407 Acquired with deteriorated credit quality 70,762 2,539 31,223 104,524 Total acquired loans and leases 191,881 27,037 175,489 394,407 Total loans and leases $ 3,351,736 $ 1,768,958 $ 1,182,822 $ 6,303,516 At December 31, 2017 Commercial Real Estate Commercial Consumer Total (In Thousands) Allowance for Loan and Lease Losses: Originated: Individually evaluated for impairment $ — $ 3,105 $ — $ 3,105 Collectively evaluated for impairment 26,366 23,078 5,003 54,447 Total originated loans and leases 26,366 26,183 5,003 57,552 Acquired: Individually evaluated for impairment — — 22 22 Collectively evaluated for impairment 145 13 17 175 Acquired with deteriorated credit quality 601 137 105 843 Total acquired loans and leases 746 150 144 1,040 Total allowance for loan and lease losses $ 27,112 $ 26,333 $ 5,147 $ 58,592 Loans and Leases: Originated: Individually evaluated for impairment $ 13,031 $ 29,386 $ 3,070 $ 45,487 Collectively evaluated for impairment 2,932,420 1,582,032 930,683 5,445,135 Total originated loans and leases 2,945,451 1,611,418 933,753 5,490,622 Acquired: Individually evaluated for impairment — 1,487 1,867 3,354 Collectively evaluated for impairment 34,244 6,399 55,921 96,564 Acquired with deteriorated credit quality 96,082 4,807 39,250 140,139 Total acquired loans and leases 130,326 12,693 97,038 240,057 Total loans and leases $ 3,075,777 $ 1,624,111 $ 1,030,791 $ 5,730,679
Summary of loans restructured or defaulted	The recorded investment in troubled debt restructurings and the associated specific allowances for loan and lease losses, in the originated and acquired loan and lease portfolios, that were modified during the periods indicated, are as follows. At and for the Year Ended December 31, 2018 Recorded Investment Specific Allowance for Loan and Lease Losses Defaulted (1) Number of Loans/ Leases At Modification At End of Period Nonaccrual Loans and Leases Number of Loans/ Leases Recorded Investment (Dollars in Thousands) Originated: Commercial real estate 1 $ 673 $ 652 $ — $ 653 — $ — Commercial 10 1,775 1,706 733 1,706 2 1,075 Equipment financing 14 2,510 2,556 37 1,351 — — Residential mortgage 2 550 550 12 341 1 341 Home equity 1 86 83 — — — — Total originated 28 5,594 5,547 782 4,051 3 1,416 Acquired: Home equity 2 249 245 — 245 — — Total acquired 2 249 245 — 245 — — Total loans and leases 30 $ 5,843 $ 5,792 $ 782 $ 4,296 3 $ 1,416 ______________________________________________________________________ (1) Includes loans and leases that have been modified within the past twelve months and subsequently had payment defaults during the period indicated. At and for the Year Ended December 31, 2017 Recorded Investment Specific Allowance for Loan and Lease Losses Defaulted (1) Number of Loans/ Leases At Modification At End of Period Nonaccrual Loans and Leases Number of Loans/ Leases Recorded Investment (Dollars in Thousands) Originated: Commercial real estate 1 $ 189 $ 189 $ — $ — — $ — Commercial 10 7,861 3,911 191 2,189 2 1,361 Equipment financing 16 2,687 2,901 137 1,440 1 188 Total originated 27 $ 10,737 $ 7,001 $ 328 $ 3,629 3 $ 1,549 ______________________________________________________________________ (1) Includes loans and leases that have been modified within the past twelve months and subsequently had payment defaults during the period indicated. There were no acquired loans and leases that met the definition of a troubled debt restructured during the twelve months ended December 31, 2017 . At and for the Year Ended December 31, 2016 Recorded Investment Specific Allowance for Loan and Lease Losses Defaulted (1) Number of Loans/ Leases At Modification At End of Period Nonaccrual Loans and Leases Number of Loans/ Leases Recorded Investment (Dollars in Thousands) Originated: Multi-family mortgage 2 $ 1,155 $ 1,114 $ — $ 1,114 — $ — Commercial 22 9,701 6,015 — 6,015 2 364 Equipment financing 3 797 524 — 524 2 341 Total originated 27 11,653 7,653 — 7,653 4 705 Acquired: Home equity 5 374 368 20 145 — — Total acquired 5 374 368 20 145 — — Total loans and leases 32 $ 12,027 $ 8,021 $ 20 $ 7,798 4 $ 705 ______________________________________________________________________ (1) Includes loans and leases that have been modified within the past twelve months and subsequently had payment defaults during the period indicated.
Schedule of troubled debt restructurings by type of modification	The following table sets forth the Company's end-of-period balances for troubled debt restructurings that were modified during the periods indicated, by type of modification. Year Ended December 31, 2018 2017 2016 (In Thousands) Loans with one modification: Extended maturity $ 1,717 $ 2,810 $ 599 Adjusted principal — 19 249 Interest only — 174 1,493 Combination maturity, principal, interest rate 3,651 1,914 5,455 Total loans modified once $ 5,368 $ 4,917 $ 7,796 Loans with more than one modification: Extended maturity $ — $ 1,910 $ 225 Combination maturity, principal, interest rate 424 174 — Total loans modified more than once $ 424 $ 2,084 $ 225

Premises and Equipment (Tables)

Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Schedule of premises and equipment	Premises and equipment consist of the following: At December 31, Estimated Useful Life 2018 2017 (In Thousands) (In Years) Land $ 12,300 $ 11,057 NA Fine art 533 495 NA Computer equipment 10,488 9,728 3 Vehicles 126 126 3 to 5 Core processing system and software 20,466 19,791 3 to 7.5 Furniture, fixtures and equipment 14,696 14,226 5 to 25 Office building and improvements 87,913 88,283 10 to 40 Total 146,522 143,706 Accumulated depreciation and amortization 70,140 63,423 Total premises and equipment $ 76,382 $ 80,283

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of changes in the carrying value of goodwill	The changes in the carrying value of goodwill for the periods indicated were as follows: Year Ended December 31, 2018 2017 2016 (In Thousands) Balance at beginning of year $ 137,890 $ 137,890 $ 137,890 Additions 22,537 — — Balance at end of year $ 160,427 $ 137,890 $ 137,890
Schedule of composition of other intangible assets	The following is a summary of the Company's other intangible assets: At December 31, 2018 At December 31, 2017 Gross Accumulated Carrying Gross Accumulated Carrying (In Thousands) Other intangible assets: Core deposits $ 38,294 $ 33,297 $ 4,997 $ 36,172 $ 31,217 $ 4,955 Trade name 1,600 511 1,089 1,600 511 1,089 Trust relationship 1,568 1,568 — 1,568 1,568 — Other intangible 442 442 — 442 442 — Total other intangible assets $ 41,904 $ 35,818 $ 6,086 $ 39,782 $ 33,738 $ 6,044
Schedule of estimated aggregate future amortization expense for intangible assets	The estimated aggregate future amortization expense for other intangible assets for each of the next five years and thereafter is as follows: Year ended December 31: Amount (In Thousands) 2019 $ 1,699 2020 1,261 2021 850 2022 494 2023 263 Thereafter 430 Total $ 4,997

Other Assets (Tables)

Other Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of information regarding the Company's investments in affordable housing projects	Further information regarding the Company's investments in affordable housing projects follows: At December 31, 2018 2017 (In Thousands) Investments in affordable housing projects included in other assets $ 10,895 $ 11,432 Unfunded commitments related to affordable housing projects included in other liabilities 1,115 1,933 Investment in affordable housing tax credits 1,885 1,745 Investment in affordable housing tax benefits 585 653 For the year ended December 31, 2018 2017 2016 (In Thousands) Investment amortization included in provision for income taxes $ 1,916 $ 1,844 $ 1,726 Amount recognized as income tax benefit 585 623 598

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2018
Banking and Thrift [Abstract]
Summary of deposits	A summary of deposits follows: December 31, 2018 December 31, 2017 Amount Weighted Average Rate Amount Weighted Average Rate (Dollars in Thousands) Demand checking accounts $ 1,033,551 — % $ 942,583 — % NOW accounts 336,317 0.10 % 350,568 0.07 % Savings accounts 619,961 0.32 % 646,359 0.25 % Money market accounts 1,675,050 1.18 % 1,724,363 0.56 % Total core deposit accounts 3,664,879 0.60 % 3,663,873 0.31 % Certificate of deposit accounts maturing: Within six months 475,303 1.20 % 363,866 0.93 % After six months but within 1 year 562,018 1.40 % 342,500 1.09 % After 1 year but within 2 years 538,435 1.85 % 300,921 1.48 % After 2 years but within 3 years 95,806 2.16 % 90,805 1.87 % After 3 years but within 4 years 46,027 1.73 % 57,926 1.79 % After 4 years but within 5 years 71,556 2.57 % 50,380 2.02 % 5+ Years 20 1.98 % 1,072 1.03 % Total certificate of deposit accounts 1,789,165 1.58 % 1,207,470 1.27 % Total deposits $ 5,454,044 0.92 % $ 4,871,343 0.55 %
Schedule of interest expense on deposit balances	Interest expense on deposit balances is summarized as follows: Year Ended December 31, 2018 2017 2016 (In Thousands) Interest-bearing deposits: NOW accounts $ 283 $ 225 $ 209 Savings accounts 1,804 1,297 1,322 Money market accounts 15,369 8,863 7,549 Certificate of deposit accounts 24,522 12,903 10,990 Total interest-bearing deposits $ 41,978 $ 23,288 $ 20,070

Borrowed Funds (Tables)

Borrowed Funds (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of borrowed funds	Borrowed funds are comprised of the following: At December 31, 2018 2017 (In Thousands) Advances from the FHLBB $ 784,375 $ 889,909 Subordinated debentures and notes 83,433 83,271 Other borrowed funds 52,734 47,639 Total borrowed funds $ 920,542 $ 1,020,819
Schedule of interest expense on borrowed funds	Interest expense on borrowed funds for the periods indicated is as follows: Year Ended December 31, 2018 2017 2016 (In Thousands) Advances from the FHLBB $ 18,650 $ 11,330 $ 10,760 Subordinated debentures and notes 5,181 5,081 5,038 Other borrowed funds 385 170 116 Total interest expense on borrowed funds $ 24,216 $ 16,581 $ 15,914
Schedule of federal home loan bank advances	FHLBB advances mature as follows: At December 31, 2018 2017 Amount Callable Amount Weighted Average Rate Amount Callable Amount Weighted Average Rate (Dollars in Thousands) Within 1 year $ 603,590 $ — 2.19 % $ 514,314 $ 55,000 1.43 % Over 1 year to 2 years 160,073 — 2.64 % 279,928 115,000 1.70 % Over 2 years to 3 years 580 — 3.07 % 16,026 — 0.47 % Over 3 years to 4 years 3,214 — 0.03 % 30,849 — 0.41 % Over 4 years to 5 years — — — % 33,217 — 0.30 % Over 5 years 16,918 — 3.45 % 15,575 — 3.95 % $ 784,375 $ — 2.30 % $ 889,909 $ 170,000 1.47 %
Schedule of information concerning repurchase agreements during the period	Information concerning other borrowed funds is as follows for the periods indicated below: Year Ended December 31, 2018 2017 (Dollars In Thousands) Outstanding at end of year $ 52,734 $ 47,639 Average outstanding for the year 46,079 45,908 Maximum outstanding at any month-end 55,144 54,064 Weighted average rate at end of year 0.16 % 0.46 % Weighted average rate paid for the year 0.83 % 0.37 %
Summary of subordinated debentures	The following table summarizes the Company's subordinated debentures and notes at the dates indicated. Carrying Amount Issue Date Rate Maturity Date Next Call Date December 31, 2018 December 31, 2017 (Dollars in Thousands) June 26, 2003 Variable; 3-month LIBOR + 3.10% June 26, 2033 March 26, 2019 $ 4,803 $ 4,778 March 17, 2004 Variable; 3-month LIBOR + 2.79% March 17, 2034 March 19, 2019 4,704 4,668 September 15, 2014 6.0% Fixed-to-Variable; 3-month LIBOR + 3.315% September 15, 2029 September 15, 2024 73,926 73,825 Total $ 83,433 $ 83,271

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of financial instruments with off-balance sheet risk	Financial instruments with off-balance-sheet risk at the dates indicated follow: At December 31, 2018 2017 (In Thousands) Financial instruments whose contract amounts represent credit risk: Commitments to originate loans and leases: Commercial real estate $ 76,642 $ 76,653 Commercial 75,713 83,270 Residential mortgage 16,363 28,745 Unadvanced portion of loans and leases 707,997 571,668 Unused lines of credit: Home equity 487,476 407,552 Other consumer 50,404 34,191 Other commercial 347 323 Unused letters of credit: Financial standby letters of credit 11,491 12,422 Performance standby letters of credit 3,075 736 Commercial and similar letters of credit 4,573 184 Loan level derivatives: Receive fixed, pay variable 714,500 494,659 Pay fixed, receive variable 714,500 494,659 Risk participation-out agreements 100,531 36,627 Risk participation-in agreements 35,838 3,825 Foreign exchange contracts: Buys foreign currency, sells U.S. currency 6,573 1,495 Sells foreign currency, buys U.S. currency 6,582 1,502
Schedule of future minimum rental payments under noncancellable operating leases	A summary of future minimum rental payments under such leases at the dates indicated follows: Year ended December 31, Minimum Rental Payments (In Thousands) 2019 $ 4,224 2020 4,932 2021 4,418 2022 3,602 2023 2,734 Thereafter 8,503 Total $ 28,413

Earnings per Share (EPS) (Table

Earnings per Share (EPS) (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Reconciliation of basic EPS and diluted EPS	The following table is a reconciliation of basic EPS and diluted EPS: For the year ended December 31, 2018 2017 2016 Basic Fully Diluted Basic Fully Diluted Basic Fully Diluted (Dollars in Thousands, Except Per Share Amounts) Numerator: Net income $ 83,062 $ 83,062 $ 50,518 $ 50,518 $ 52,362 $ 52,362 Denominator: Weighted average shares outstanding 79,669,668 79,669,668 74,459,508 74,459,508 70,261,954 70,261,954 Effect of dilutive securities — 239,583 — 351,900 — 182,129 Adjusted weighted average shares outstanding 79,669,668 79,909,251 74,459,508 74,811,408 70,261,954 70,444,083 EPS $ 1.04 $ 1.04 $ 0.68 $ 0.68 $ 0.74 $ 0.74

Comprehensive Income_(Loss) (Ta

Comprehensive Income/(Loss) (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Schedule of changes in accumulated other comprehensive (loss) income by component, net of tax	Changes in accumulated other comprehensive loss by component, net of tax, were as follows for the periods indicated: Year Ended December 31, 2018 Investment Securities Available-for-Sale Postretirement Benefits Accumulated Other Comprehensive Loss (In Thousands) Balance at December 31, 2017 $ (6,113 ) $ 163 $ (5,950 ) Other comprehensive loss (3,599 ) 89 (3,510 ) Balance at December 31, 2018 $ (9,712 ) $ 252 $ (9,460 ) Year Ended December 31, 2017 Investment Securities Available-for-Sale Postretirement Benefits Accumulated Other Comprehensive Loss (In Thousands) Balance at December 31, 2016 $ (4,213 ) $ 395 $ (3,818 ) Other comprehensive loss (817 ) (252 ) (1,069 ) Reclassification due to adoption of ASU 2018-02 (1,083 ) 20 (1,063 ) Balance at December 31, 2017 $ (6,113 ) $ 163 $ (5,950 ) Year Ended December 31, 2016 Investment Securities Available-for-Sale Postretirement Benefits Accumulated Other Comprehensive Loss (In Thousands) Balance at December 31, 2015 $ (2,827 ) $ 351 $ (2,476 ) Other comprehensive (loss) income (1,386 ) 44 (1,342 ) Balance at December 31, 2016 $ (4,213 ) $ 395 $ (3,818 )

Derivatives and Hedging Activ_2

Derivatives and Hedging Activities (Tables)	12 Months Ended
	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of fair value and classification of derivative financial instruments on the consolidated balance sheets and the effect of the derivative financial instruments on the consolidated income statements	The following tables presents the Company's customer related derivative positions for the periods indicated below for those derivatives not designated as hedging. Notional Amount Maturing Number of Positions Less than 1 year Less than 2 years Less than 3 years Less than 4 years Thereafter Total Fair Value December 31, 2018 (Dollars In Thousands) Loan level derivatives Receive fixed, pay variable 86 $ 1,931 $ 26,419 $ — $ 31,762 $ 654,388 $ 714,500 $ 6,081 Pay fixed, receive variable 86 1,931 26,419 — 31,762 654,388 714,500 6,081 Risk participation-out agreements 26 — 14,892 — — 85,639 100,531 344 Risk participation-in agreements 5 — — — — 35,838 35,838 84 Foreign exchange contracts Buys foreign currency, sells U.S. currency 22 $ 6,573 $ — $ — $ — $ — $ 6,573 $ 123 Sells foreign currency, buys U.S. currency 37 6,582 — — — — 6,582 131 Notional Amount Maturing Number of Positions Less than 1 year Less than 2 years Less than 3 years Less than 4 years Thereafter Total Fair Value December 31, 2017 (Dollars In Thousands) Loan level derivatives Receive fixed, pay variable 66 $ 3,903 $ 2,036 $ 27,992 $ — $ 460,728 $ 494,659 $ 8,865 Pay fixed, receive variable 66 3,903 2,036 27,992 — 460,728 494,659 8,865 Risk participation-out agreements 8 — — 8,613 — 28,014 36,627 65 Risk participation-in agreements 1 — — — — 3,825 3,825 10 Foreign exchange contracts Buys foreign currency, sells U.S. currency 22 $ 1,495 $ — $ — $ — $ — $ 1,495 $ 65 Sells foreign currency, buys U.S. currency 44 1,502 — — — — 1,502 72 Changes in the fair value are recognized directly in the Company's consolidated statements of income and are included in other non-interest income in the consolidated statements of income. The table below presents the gain (loss) recognized in income due to changes in the fair value for the year ended December 31, 2018 and 2017 . Year Ended December 31, 2018 2017 (In Thousands) Gain recognized in income on: Risk participation-out agreements 205 55 Foreign exchange contracts 1 7 Total $ 206 $ 62
Schedule of offsetting derivatives and amounts subject to master netting agreements not offset in the audited consolidated balance sheet	The tables below present the offsetting of derivatives and amounts subject to master netting agreements not offset in the consolidated balance sheet at the dates indicated. At December 31, 2018 Gross Gross Amounts Statement of Financial Position Net Amounts Presented in the Statement of Financial Position Gross Amounts Not Offset in the Statement of Financial Position Net Amount Financial Instruments Pledged Cash Collateral Pledged (In Thousands) Asset derivatives Loan level derivatives $ 22,013 $ — $ 22,013 $ — $ 50 $ 21,963 Risk participation-out agreements 344 — 344 — — 344 Foreign exchange contracts 131 — 131 — — 131 Total $ 22,488 $ — $ 22,488 $ — $ 50 $ 22,438 Liability derivatives Loan level derivatives $ 22,013 $ — $ 22,013 $ 5,877 $ — $ 16,136 Risk participation-in agreements 84 — 84 — — 84 Foreign exchange contracts 123 — 123 — — 123 Total $ 22,220 $ — $ 22,220 $ 5,877 $ — $ 16,343 At December 31, 2017 Gross Gross Amounts Statement of Financial Position Net Amounts Presented in the Statement of Financial Position Gross Amounts Not Offset in the Statement of Financial Position Net Amount Financial Instruments Pledged Cash Collateral Pledged (In Thousands) Asset derivatives Loan level derivatives $ 8,865 $ — $ 8,865 $ — $ — $ 8,865 Risk participation-out agreements 65 — 65 — — 65 Foreign exchange contracts 72 — 72 — — 72 Total $ 9,002 $ — $ 9,002 $ — $ — $ 9,002 Liability derivatives Loan level derivatives $ 8,865 $ — $ 8,865 $ 25,159 $ 1,510 $ — Risk participation-in agreements 10 — 10 — — 10 Foreign exchange contracts 65 — 65 — — 65 Total $ 8,940 $ — $ 8,940 $ 25,159 $ 1,510 $ 75

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of income tax expense	Income tax expense is comprised of the following amounts: Year Ended December 31, 2018 2017 2016 (In Thousands) Current provision: Federal $ 23,949 $ 27,825 $ 22,954 State 7,693 5,013 5,116 Total current provision 31,642 32,838 28,070 Deferred benefit (provision): Federal (4,323 ) 10,209 2,271 State (1,130 ) 589 51 Total deferred benefit (provision) (5,453 ) 10,798 2,322 Total provision for income taxes $ 26,189 $ 43,636 $ 30,392
Schedule of reconciliation of income tax expense	Total provision for income taxes differed from the amounts computed by applying the statutory U.S. federal income tax rate of 21.0% in 2018 and 35.0% in 2017 and 2016 to income before tax expense as a result of the following: Year Ended December 31, 2018 2017 2016 (Dollars In Thousands) Expected income tax expense at statutory federal tax rate $ 23,675 $ 34,039 $ 29,965 State taxes, net of federal income tax benefit 5,184 3,641 3,358 Bank-owned life insurance (218 ) (364 ) (368 ) Tax-exempt interest income (487 ) (873 ) (826 ) Income attributable to noncontrolling interest in subsidiary (933 ) (870 ) (1,163 ) Merger and acquisition expense 32 138 — Tax Reform Act Adjustment (707 ) 8,965 — Investments in affordable housing projects (358 ) (653 ) (640 ) Other, net 1 (387 ) 66 Total provision for income taxes $ 26,189 $ 43,636 $ 30,392 Effective income tax rate 23.2 % 44.9 % 35.5 %
Schedule of the tax effects of temporary differences that give rise to significant portions of the deferred tax assets and liabilities	The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and liabilities at the dates indicated are as follows: At December 31, 2018 2017 (In Thousands) Deferred tax assets: Allowance for loan and lease losses $ 15,936 $ 15,618 Deferred compensation 4,692 1,032 Supplemental Executive Retirement Plans 2,846 2,805 Unrealized loss on investment securities available-for-sale 2,737 1,728 Net operating loss carryforwards 976 415 Postretirement benefits 391 400 Nonaccrual interest 482 551 Accrued expense 372 563 Restricted stock and stock option plans 497 621 Employee stock ownership plan 106 124 Other 331 67 Total gross deferred tax assets 29,366 23,924 Deferred tax liabilities: Identified intangible assets and goodwill 2,428 2,778 Deferred loan origination costs, net 3,537 2,918 Depreciation 789 1,866 Prepaid expense 116 109 Acquisition fair value adjustments 1,001 1,192 Total gross deferred tax liabilities 7,871 8,863 Net deferred tax asset $ 21,495 $ 15,061

Regulatory Capital Requiremen_2

Regulatory Capital Requirements (Tables)	12 Months Ended
	Dec. 31, 2018
Banking and Thrift [Abstract]
Schedule of the Company's and the bank's actual and required capital amounts and ratios	Actual Minimum Required for Capital Adequacy Purposes Minimum Required for Fully Phased in Capital Adequacy Purposes plus Capital Conservation Buffer Minimum Required to be Considered “Well-Capitalized” Under Prompt Corrective Action Provisions Amount Ratio Amount Ratio Amount Ratio Amount Ratio (Dollars in Thousands) At December 31, 2018: Brookline Bancorp, Inc. Common equity Tier 1 capital ratio (1) $ 745,103 11.94 % $ 280,818 4.50 % $ 436,828 7.00 % N/A N/A Tier 1 leverage capital ratio (2) 765,089 10.58 % 289,259 4.00 % 289,259 4.00 % N/A N/A Tier 1 risk-based capital ratio (3) 765,089 12.26 % 374,432 6.00 % 530,445 8.50 % N/A N/A Total risk-based capital ratio (4) 899,563 14.42 % 499,064 8.00 % 655,022 10.50 % N/A N/A Brookline Bank Common equity Tier 1 capital ratio (1) $ 495,798 12.06 % $ 184,999 4.50 % $ 287,777 7.00 % $ 267,221 6.50 % Tier 1 leverage capital ratio (2) 506,277 11.02 % 183,767 4.00 % 183,767 4.00 % 229,708 5.00 % Tier 1 risk-based capital ratio (3) 506,277 12.32 % 246,563 6.00 % 349,298 8.50 % 328,751 8.00 % Total risk-based capital ratio (4) 545,533 13.27 % 328,882 8.00 % 431,658 10.50 % 411,102 10.00 % BankRI Common equity Tier 1 capital ratio (1) $ 209,670 11.37 % $ 82,983 4.50 % $ 129,084 7.00 % $ 119,864 6.50 % Tier 1 leverage capital ratio (2) 209,670 9.35 % 89,698 4.00 % 89,698 4.00 % 112,123 5.00 % Tier 1 risk-based capital ratio (3) 209,670 11.37 % 110,644 6.00 % 156,745 8.50 % 147,525 8.00 % Total risk-based capital ratio (4) 227,674 12.35 % 147,481 8.00 % 193,569 10.50 % 184,351 10.00 % First Ipswich Common equity Tier 1 capital ratio (1) $ 39,655 13.91 % $ 12,829 4.50 % $ 19,956 7.00 % $ 18,530 6.50 % Tier 1 leverage capital ratio (2) 39,655 9.59 % 16,540 4.00 % 16,540 4.00 % 20,675 5.00 % Tier 1 risk-based capital ratio (3) 39,655 13.91 % 17,105 6.00 % 24,232 8.50 % 22,807 8.00 % Total risk-based capital ratio (4) 42,944 15.06 % 22,812 8.00 % 29,941 10.50 % 28,515 10.00 % _______________________________________________________________________________ (1) Common equity Tier 1 capital ratio is calculated by dividing common equity Tier 1 capital by risk-weighted assets. The ratio was established as part of the implementation of Basel III, effective January 1, 2015. (2) Tier 1 leverage capital ratio is calculated by dividing Tier 1 capital by average assets. (3) Tier 1 risk-based capital ratio is calculated by dividing Tier 1 capital by risk-weighted assets. (4) Total risk-based capital ratio is calculated by dividing total capital by risk-weighted assets. The following table presents actual and required capital ratios as of December 31, 2017 for the Company and the Banks under the regulatory capital rules then in effect. Actual Minimum Required for Capital Adequacy Purposes Minimum Required for Fully Phased in Capital Adequacy Purposes plus Capital Conservation Buffer Minimum Required to be Considered “Well-Capitalized” Under Prompt Corrective Action Provisions Amount Ratio Amount Ratio Amount Ratio Amount Ratio (Dollars in Thousands) At December 31, 2017: Brookline Bancorp, Inc. Common equity Tier 1 capital ratio (1) $ 669,238 12.02 % $ 250,547 4.50 % $ 389,739 7.00 % N/A N/A Tier 1 leverage capital ratio (2) 687,299 10.43 % 263,585 4.00 % 263,585 4.00 % N/A N/A Tier 1 risk-based capital ratio (3) 687,299 12.34 % 334,181 6.00 % 473,423 8.50 % N/A N/A Total risk-based capital ratio (4) 821,373 14.75 % 445,490 8.00 % 584,706 10.50 % N/A N/A Brookline Bank Common equity Tier 1 capital ratio (1) $ 414,282 11.56 % $ 161,269 4.50 % $ 250,863 7.00 % $ 232,944 6.50 % Tier 1 leverage capital ratio (2) 423,035 10.35 % 163,492 4.00 % 163,492 4.00 % 204,365 5.00 % Tier 1 risk-based capital ratio (3) 423,035 11.81 % 214,920 6.00 % 304,471 8.50 % 286,561 8.00 % Total risk-based capital ratio (4) 463,986 12.95 % 286,632 8.00 % 376,205 10.50 % 358,290 10.00 % BankRI Common equity Tier 1 capital ratio (1) $ 193,849 11.38 % $ 76,654 4.50 % $ 119,239 7.00 % $ 110,722 6.50 % Tier 1 leverage capital ratio (2) 193,849 9.16 % 84,650 4.00 % 84,650 4.00 % 105,813 5.00 % Tier 1 risk-based capital ratio (3) 193,849 11.38 % 102,205 6.00 % 144,791 8.50 % 136,273 8.00 % Total risk-based capital ratio (4) 210,025 12.33 % 136,269 8.00 % 178,853 10.50 % 170,337 10.00 % First Ipswich Common equity Tier 1 capital ratio (1) $ 37,502 13.38 % $ 12,613 4.50 % $ 19,620 7.00 % $ 18,218 6.50 % Tier 1 leverage capital ratio (2) 37,502 9.44 % 15,891 4.00 % 15,891 4.00 % 19,863 5.00 % Tier 1 risk-based capital ratio (3) 37,502 13.38 % 16,817 6.00 % 23,824 8.50 % 22,423 8.00 % Total risk-based capital ratio (4) 40,625 14.50 % 22,414 8.00 % 29,418 10.50 % 28,017 10.00 % _______________________________________________________________________________ (1) Common equity Tier 1 capital ratio is calculated by dividing common equity Tier 1 capital by risk-weighted assets. The ratio was established as part of the implementation of Basel III, effective January 1, 2015. (2) Tier 1 leverage capital ratio is calculated by dividing Tier 1 capital by average assets. (3) Tier 1 risk-based capital ratio is calculated by dividing Tier 1 capital by risk-weighted assets. (4) Total risk-based capital ratio is calculated by dividing total capital by risk-weighted assets.

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Reconciliation of Changes in Plan Assets and Benefit Obligation	The following table presents the change in plan assets and change in benefit obligation: Year Ended December 31, 2018 2017 2016 (In Thousands) Change in plan assets: Fair value of plan assets at beginning of year $ — $ — $ — Employer contributions 31 19 21 Benefits paid (31 ) (19 ) (21 ) Fair value of plan assets at end of year $ — $ — $ — Change in benefit obligation: Benefit obligation at beginning of year $ 1,534 $ 1,135 $ 1,188 Service cost 70 49 48 Interest cost 59 43 45 Estimated benefits paid (31 ) (19 ) (21 ) Actuarial loss (gain) (142 ) 326 (125 ) Benefit obligation at end of year $ 1,490 $ 1,534 $ 1,135 Funded status at end of year $ 1,490 $ 1,534 $ 1,135 Accumulated benefit obligation at end of year $ 1,490 $ 1,534 $ 1,135
Schedule of the components of net periodic postretirement benefit cost and other amounts recognized in other comprehensive income	The following table presents the components of net periodic postretirement benefit cost and other amounts recognized in other comprehensive income: Year Ended December 31, 2018 2017 2016 (In Thousands) Net periodic benefit expense: Service cost $ 70 $ 49 $ 48 Interest cost 59 43 45 Prior service credit (21 ) (21 ) (21 ) Actuarial gain — (47 ) (42 ) Net periodic benefit expense $ 108 $ 24 $ 30 Changes in postretirement benefit obligation recognized in other comprehensive income: Net actuarial (loss) gain 142 $ (401 ) $ 90 Prior service credit (21 ) (21 ) (21 ) Total pre-tax changes in postretirement benefit obligation recognized in other comprehensive income $ 121 $ (422 ) $ 69
Schedule of effect of 1% change in assumed health care cost trend rates	A 1% change in assumed health care cost trend rates would have the following effects: Year Ended 1% Increase 1% Decrease (In Thousands) Effect on total service and interest cost components of net periodic postretirement benefit costs $ 31 $ (24 ) Effect on the accumulated postretirement benefit obligation 316 (250 )
Activity under recognition and retention plans	Activity under the recognition and retention plans was as follows: Restricted Stock Awards Outstanding Weighted Average Price per Share (Dollars in Thousands, Except Per Share Amounts) Recognition and Retention Plans: Outstanding at December 31, 2017 455,283 $ 12.64 Granted 169,582 18.40 Vested (195,660 ) 12.53 Forfeited / Canceled (38,570 ) 12.48 Outstanding at December 31, 2018 390,635 $ 15.21 Unrecognized compensation cost $ 3,735 Weighted average remaining recognition period (months) 22
Schedule of stock option activity	Activity under the option plans was as follows: Options Outstanding Weighted Average Exercise Price Per Share Aggregate Intrinsic Value Weighted Average Contractual Term (In Years) (Dollars in Thousands, Except Per Share Amounts) Employee Stock Options: Outstanding at December 31, 2017 50,000 $ 10.80 Granted — — Exercised (45,000 ) 10.90 Forfeited / Canceled — — Outstanding at December 31, 2018 5,000 $ 9.90 $ 20 1.8 Exercisable at December 31, 2018 5,000 $ 9.90 $ 20 1.8

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2018
Fair value of assets and liabilities
Schedule of quantitative information about significant unobservable inputs (Level 3) for assets measured at fair value on a recurring basis	The table below presents quantitative information about significant unobservable inputs (Level 3) for assets measured at fair value on a recurring basis at the dates indicated. Fair Value Valuation Technique At December 31, 2018 At December 31, 2017 (Dollars in Thousands) Collateral-dependent impaired loans and leases $ 11,451 $ 18,091 Appraisal of collateral (1) Other real estate owned 3,054 3,235 Appraisal of collateral (1) _______________________________________________________________________________ (1) Fair value is generally determined through independent appraisals of the underlying collateral. The Company may also use another available source of collateral assessment to determine a reasonable estimate of the fair value of the collateral. Appraisals may be adjusted by management for qualitative factors such as economic factors and estimated liquidation expenses. The range of the unobservable inputs used may vary but is generally 0% - 10% on the discount for costs to sell and 0% - 15% on appraisal adjustments.
Summary of the carrying values and estimated fair values	The following table presents the carrying amount, estimated fair value, and placement in the fair value hierarchy of the Company's financial instruments at the dates indicated. This table excludes financial instruments for which the carrying amount approximates fair value. Financial assets for which the fair value approximates carrying value include cash and cash equivalents, restricted equity securities, and accrued interest receivable. Financial liabilities for which the fair value approximates carrying value include non-maturity deposits, short-term borrowings, and accrued interest payable. There were no transfers between levels during 2018 . Fair Value Measurements Carrying Value Estimated Fair Value Level 1 Inputs Level 2 Inputs Level 3 Inputs (In Thousands) At December 31, 2018 Financial assets: Investment securities held-to-maturity: GSE debentures $ 50,546 $ 49,601 $ — $ 49,601 $ — GSE MBSs 11,426 11,131 — 11,131 — Municipal obligations 52,304 51,598 — 51,598 — Foreign government obligations 500 500 — — 500 Loans held-for-sale 3,247 3,247 — 3,247 — Loans and leases, net 6,244,824 6,154,704 — — 6,154,704 Restricted equity securities 61,751 61,751 — — 61,751 Financial liabilities: Certificates of deposit 1,789,165 1,778,860 — 1,778,860 — Borrowed funds 920,542 886,545 — 886,545 — At December 31, 2017 Financial assets: Investment securities held-to-maturity: GSE debentures $ 41,612 $ 40,801 $ — $ 40,801 $ — GSE MBSs 13,923 13,705 — 13,705 — Municipal obligations 53,695 53,517 — 53,517 — Foreign government obligations 500 500 — — 500 Loans held-for-sale 2,628 2,628 — 2,628 — Loans and leases, net 5,672,087 5,594,543 — — 5,594,543 Restricted equity securities 59,369 59,369 — — 59,369 Financial liabilities: Certificates of deposit 1,207,470 1,198,201 — 1,198,201 — Borrowed funds 1,020,819 995,335 — 995,335 —
Recurring basis
Fair value of assets and liabilities
Schedule of assets and liabilities measured at fair value on a recurring and non-recurring basis	The following table set forth the carrying value of assets and liabilities measured at fair value on a recurring basis at December 31, 2018 and 2017 : Carrying Value as of December 31, 2018 Level 1 Level 2 Level 3 Total (In Thousands) Assets: Investment securities available-for-sale: Debt securities: GSE debentures $ — $ 181,079 $ — $ 181,079 GSE CMOs — 103,130 — 103,130 GSE MBSs — 165,089 — 165,089 SBA commercial loan asset-backed securities — 51 — 51 Corporate debt obligations — 39,708 — 39,708 U.S. Treasury bonds — 13,736 — 13,736 Total investment securities available-for-sale $ — $ 502,793 $ — $ 502,793 Equity securities held-for-trading $ 3,235 $ 972 $ — $ 4,207 Loan level derivatives — 22,013 — 22,013 Risk participation-out agreements — 344 — 344 Foreign exchange contracts — 131 — 131 Liabilities: Loan level derivatives $ — $ 22,013 $ — $ 22,013 Risk participation-in agreements — 84 — 84 Foreign exchange contracts — 123 — 123 Carrying Value as of December 31, 2017 Level 1 Level 2 Level 3 Total (In Thousands) Assets: Investment securities available-for-sale: Debt securities: GSE debentures $ — $ 149,924 $ — $ 149,924 GSE CMOs — 127,022 — 127,022 GSE MBSs — 189,313 — 189,313 SBA commercial loan asset-backed securities — 72 — 72 Corporate debt obligations — 62,683 — 62,683 U.S. Treasury bonds — 8,730 — 8,730 Trust preferred securities — 1,398 — 1,398 Marketable equity securities — 982 — 982 Total investment securities available-for-sale $ — $ 540,124 $ — $ 540,124 Loan level derivatives — 8,865 — 8,865 Risk participation-out agreements — 65 — 65 Foreign exchange contracts — 72 — 72 Liabilities: Loan level derivatives $ — $ 8,865 $ — $ 8,865 Risk participation-in agreements — 10 — 10 Foreign exchange contracts — 65 — 65
Nonrecurring basis
Fair value of assets and liabilities
Schedule of assets and liabilities measured at fair value on a recurring and non-recurring basis	Assets and liabilities measured at fair value on a non-recurring basis as of December 31, 2018 and 2017 are summarized below: Carrying Value as of December 31, 2018 Level 1 Level 2 Level 3 Total (In Thousands) Assets measured at fair value on a non-recurring basis: Collateral-dependent impaired loans and leases $ — $ — $ 11,451 $ 11,451 OREO — — 3,054 3,054 Repossessed assets — 965 — 965 Total assets measured at fair value on a non-recurring basis $ — $ 965 $ 14,505 $ 15,470 Carrying Value as of December 31, 2017 Level 1 Level 2 Level 3 Total (In Thousands) Assets measured at fair value on a non-recurring basis: Collateral-dependent impaired loans and leases $ — $ — $ 21,195 $ 21,195 OREO — — 3,235 3,235 Repossessed assets — 1,184 — 1,184 Total assets measured at fair value on a non-recurring basis $ — $ 1,184 $ 24,430 $ 25,614

Condensed Parent Company Fina_2

Condensed Parent Company Financial Statements (Tables)	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Disclosure [Abstract]
Balance Sheets	Balance Sheets At December 31, 2018 2017 (In Thousands) ASSETS Cash and due from banks $ 33,663 $ 5,511 Short-term investments 33 32 Total cash and cash equivalents 33,696 5,543 Equity securities held-for-trading 3,235 — ESOP loan to Brookline Bank 1,002 1,252 Intercompany loan to Brookline Bank 40,000 80,000 Restricted equity securities 101 100 Premises and equipment, net 4,318 6,032 Deferred tax asset 1,499 — Investment in subsidiaries, at equity 864,798 753,056 Goodwill 35,267 35,267 Other assets 5,400 6,627 Total assets $ 989,316 $ 887,877 LIABILITIES AND STOCKHOLDERS' EQUITY Borrowed funds $ 83,433 $ 83,271 Deferred tax liability — 608 Accrued expenses and other liabilities 5,743 168 Total liabilities 89,176 84,047 Stockholders' equity: Common stock, $0.01 par value; 200,000,000 shares authorized; 85,177,172 shares issued and 81,695,695 shares issued, respectively 852 817 Additional paid-in capital 755,629 699,976 Retained earnings, partially restricted 212,838 161,217 Accumulated other comprehensive loss (9,460 ) (5,950 ) Treasury stock, at cost; 5,020,025 shares and 4,440,665 shares, respectively (59,120 ) (51,454 ) Unallocated common stock held by ESOP; 109,950 shares and 142,332 shares, respectively (599 ) (776 ) Total stockholders' equity 900,140 803,830 Total liabilities and stockholders' equity $ 989,316 $ 887,877
Statements of Income	Statements of Income Year Ended December 31, 2018 2017 2016 (In Thousands) Interest and dividend income: Dividend income from subsidiaries $ — $ 7,317 $ 109 Marketable and restricted equity securities 37 — — ESOP loan to Brookline Bank 98 120 141 Intercompany loan to Brookline Bank 1,722 532 — Total interest and dividend income 1,857 7,969 250 Interest expense: Borrowed funds 5,223 5,123 5,080 Net interest income (3,366 ) 2,846 (4,830 ) Non-interest income: Gain on securities, net 71 — — Other 16 — 15 Total non-interest income 87 — 15 Non-interest expense: Compensation and employee benefits 345 391 82 Occupancy 1,586 1,584 1,582 Equipment and data processing (1) (798 ) (1,011 ) (1,190 ) Directors' fees 417 453 700 Franchise taxes 321 180 180 Insurance 534 528 490 Professional services 364 470 245 Advertising and marketing 19 4 — Merger and acquisition expense 452 411 — Other (2) (1,140 ) (1,224 ) (1,300 ) Total non-interest expense 2,100 1,786 789 Loss before income taxes (5,379 ) 1,060 (5,604 ) Credit for income taxes (1,976 ) (1,944 ) (1,779 ) Loss before equity in undistributed income of subsidiaries (3,403 ) 3,004 (3,825 ) Equity in undistributed income of subsidiaries 86,465 47,514 56,187 Net income $ 83,062 $ 50,518 $ 52,362 _______________________________________________________________________________ (1) The Parent Company received a net benefit in 2018, 2017 and 2016 from the intercompany allocation of expense that is eliminated in consolidation. (2) The Parent Company received a net benefit in 2018, 2017 and 2016 from the intercompany allocation of expense that is eliminated in consolidation.
Statements of Cash Flows	Statements of Cash Flows Year Ended December 31, 2018 2017 2016 (In Thousands) Cash flows from operating activities: Net income attributable to parent company $ 83,062 $ 50,518 $ 52,362 Adjustments to reconcile net income to net cash provided from operating activities: Equity in undistributed income of subsidiaries (86,465 ) (47,514 ) (56,187 ) Depreciation of premises and equipment 3,073 2,856 2,735 Amortization of debt issuance costs 100 100 101 Equity securities held-for-trading (3,235 ) — — Other operating activities, net (31,014 ) (5,885 ) 30,895 Net cash (used for) provided from operating activities (34,479 ) 75 29,906 Cash flows from investing activities: Repayment of ESOP loan by Brookline Bank 250 250 250 Pay down (issuance) of intercompany loan to Brookline Bank 40,000 (80,000 ) — Purchase of restricted equity securities (1 ) — — Purchase of premises and equipment (1,359 ) (1,942 ) (641 ) Net cash provided from (used for) investing activities 38,890 (81,692 ) (391 ) Cash flows from financing activities: Proceeds from issuance of common stock — 81,943 — Common stock issued for acquisition 55,183 — — Payment of dividends on common stock (31,441 ) (27,035 ) (25,366 ) Net cash provided from (used for) financing activities 23,742 54,908 (25,366 ) Net increase (decrease) in cash and cash equivalents 28,153 (26,709 ) 4,149 Cash and cash equivalents at beginning of year 5,543 32,252 28,103 Cash and cash equivalents at end of year $ 33,696 $ 5,543 $ 32,252 Supplemental disclosures of cash flow information: Acquisition of First Commons Bank, N.A.: Fair value of assets acquired, net of cash and cash equivalents acquired $ 292,025 $ — $ — Fair value of liabilities assumed 278,988 — —

Quarterly Results of Operatio_2

Quarterly Results of Operations (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Schedule of quarterly results of operations	2018 Quarters Fourth Third Second First (Dollars in Thousands Except Per Share Data) Interest and dividend income $ 83,544 $ 80,636 $ 78,074 $ 71,639 Interest expense 20,385 18,304 15,357 12,148 Net interest income 63,159 62,332 62,717 59,491 Provision for credit losses 123 2,717 1,470 641 Net interest income after provision for credit losses 63,036 59,615 61,247 58,850 Loan level derivative income, net 1,811 2,192 571 866 (Loss) gain on investment securities, net (692 ) (243 ) — 1,162 Gain on sales of loans and leases held-for-sale 327 535 722 299 Other non-interest income 5,015 4,585 4,233 3,841 Amortization of identified intangible assets (537 ) (537 ) (539 ) (467 ) Other non-interest expense (39,745 ) (36,773 ) (37,163 ) (39,471 ) Income before provision for income taxes 29,215 29,374 29,071 25,080 Provision for income taxes 7,055 6,140 7,342 5,652 Net income before noncontrolling interest in subsidiary 22,160 23,234 21,729 19,428 Less net income attributable to noncontrolling interest in subsidiary 1,022 774 898 795 Net income attributable to Brookline Bancorp, Inc. $ 21,138 $ 22,460 $ 20,831 $ 18,633 Earnings per share: Basic $ 0.26 $ 0.28 $ 0.26 $ 0.24 Diluted 0.26 0.28 0.26 0.24 Average common shares outstanding: Basic 80,258,489 80,315,050 80,184,977 77,879,593 Diluted 80,407,558 80,515,467 80,505,614 78,167,800 Common stock price: High $ 16.97 $ 19.05 $ 19.25 $ 17.05 Low 12.86 16.70 15.90 15.60 Dividends per share $ 0.105 $ 0.100 $ 0.100 $ 0.090 2017 Quarters Fourth Third Second First (Dollars in Thousands Except Per Share Data) Interest and dividend income $ 68,337 $ 67,176 $ 65,186 $ 62,351 Interest expense 10,680 10,333 9,603 9,253 Net interest income 57,657 56,843 55,583 53,098 Provision for credit losses 1,802 2,911 873 13,402 Net interest income after provision for credit losses 55,855 53,932 54,710 39,696 Loan level derivative income, net 755 844 186 402 Gain on sales of investment securities, net — — — 11,393 Gain on sales of loans and leases held-for-sale 935 1,049 307 353 Other non-interest income 4,125 4,080 3,984 3,760 Amortization of identified intangible assets (519 ) (519 ) (519 ) (532 ) Other non-interest expense (34,633 ) (34,889 ) (34,276 ) (33,224 ) Income before provision for income taxes 26,518 24,497 24,392 21,848 Provision for income taxes 18,712 8,330 8,759 7,835 Net income before noncontrolling interest in subsidiary 7,806 16,167 15,633 14,013 Less net income attributable to noncontrolling interest in subsidiary 979 801 753 568 Net income attributable to Brookline Bancorp, Inc. $ 6,827 $ 15,366 $ 14,880 $ 13,445 Earnings per share: Basic $ 0.09 $ 0.20 $ 0.20 $ 0.19 Diluted 0.09 0.20 0.20 0.19 Average common shares outstanding: Basic 76,583,712 76,452,539 74,325,013 70,386,766 Diluted 76,868,307 76,961,948 74,810,088 70,844,096 Common stock price: High $ 16.35 $ 15.50 $ 15.95 $ 16.75 Low 14.50 13.75 13.75 14.50 Dividends per share $ 0.09 $ 0.09 $ 0.09 $ 0.09

Basis of Presentation (Details)

Basis of Presentation (Details)	Mar. 01, 2018USD ($)branchshares	Dec. 31, 2018USD ($)classbankofficesegment	Dec. 31, 2017USD ($)	Jan. 01, 2019USD ($)
Basis of Presentation
Number of full-service banking offices | bank		25
Number of lending offices | office		2
Percentage of insurance offered		100.00%
Impairment of restricted securities		$ 0	$ 0
Number of days past due, non-accrual status (in days)		90 days
Period after which a non-accrual loan is restructured (in months)		6 months
Total loans and leases		$ 6,303,516,000	5,730,679,000
BOLI, as percentage of capital plus reserves, maximum, individual carrier (as a percent)		10.00%
BOLI, as percentage of capital plus reserves, maximum, aggregate (as a percent)		25.00%
Number of reportable segments | segment		1
Operating lease future minimum payments due		$ 28,400,000
Reclassification due to the adoption of ASU No. 2018-02			1,100,000
Minimum
Basis of Presentation
Term of operating lease		5 years
Maximum
Basis of Presentation
Term of operating lease		25 years
Taxi Medallion Portfolio
Basis of Presentation
Total loans and leases		$ 13,700,000	19,700,000
Commercial real estate
Basis of Presentation
Number of loan classes within specific portfolio | class		3
Commercial loans
Basis of Presentation
Number of loan classes within specific portfolio | class		3
Total loans and leases		$ 1,768,958,000	$ 1,624,111,000
Consumer Loan
Basis of Presentation
Number of loan classes within specific portfolio | class		3
BankRI
Basis of Presentation
Number of full-service banking offices | bank		20
First Ipswich
Basis of Presentation
Number of full-service banking offices | bank		6
Eastern Funding LLC
Basis of Presentation
Percentage of ownership in subsidiary		84.10%
First Commons Bank
Basis of Presentation
Number of businesses acquired | branch	2
Loans acquired	$ 262,304,000
Deposits acquired	273,701,000
Total transaction value	$ 56,000,000
Share exchange ratio	1.089
Equity interest issued value assigned	$ 851,000
Equity interest issued value assigned, number of shares (in shares) | shares	3,481,477
Accounting Standards Update 2016-02 | Subsequent Event
Basis of Presentation
Right of use asset				$ 23,600,000
Operating lease, liability				$ 23,600,000

Acquisitions (Narrative) (Detai

Acquisitions (Narrative) (Details) $ in Thousands	Mar. 01, 2018USD ($)branchshares	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Business Acquisition [Line Items]
Merger and acquisition expense										$ 3,787	$ 411	$ 0
Amortization of identified intangible assets		$ 537	$ 537	$ 539	$ 467	$ 519	$ 519	$ 519	$ 532	2,080	$ 2,089	$ 2,500
First Commons Bank
Business Acquisition [Line Items]
Number of businesses acquired | branch	2
Total transaction value	$ 56,000
Share exchange ratio	1.089
Equity interest issued value assigned	$ 851
Equity interest issued value assigned, number of shares (in shares) | shares	3,481,477
Merger and acquisition expense										3,600
Federal home loan bank stock	$ 880
Federal reserve bank stock	1,000
Incomplete adjustment, loans	1,600
Core deposit and other intangibles	2,122
Incomplete adjustment, certificates of deposits	1,200
Loans and Finance Receivables | First Commons Bank
Business Acquisition [Line Items]
Incomplete adjustment, accretion expense		133								445
Certificates of Deposit | First Commons Bank
Business Acquisition [Line Items]
Incomplete adjustment, accretion expense		245								817
Core deposits | First Commons Bank
Business Acquisition [Line Items]
Core deposit and other intangibles	$ 2,100
Amortization of identified intangible assets		$ 123								$ 410

Acquisitions (Assets Acquired a

Acquisitions (Assets Acquired and Liabilities Assumed) (Details) - First Commons Bank $ in Thousands	Mar. 01, 2018USD ($)
ASSETS
Cash	$ 42,995
Restricted stock	1,884
Loans	262,304
Premises and equipment	583
Goodwill	22,537
Core deposit and other intangibles	2,122
Other assets	2,595
Total assets acquired	335,020
LIABILITIES
Deposits	273,701
Borrowings	5,000
Other liabilities	287
Total liabilities assumed	278,988
Purchase price	$ 56,032

Cash, Cash Equivalents and Sh_2

Cash, Cash Equivalents and Short-Term Investments (Short-term Investments) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Short-term investments
FRB interest bearing reserve	$ 34,914	$ 28,263
FHLB overnight deposits	4,628	4,676
Federal funds sold	2,500	2,444
Total short-term investments	$ 42,042	$ 35,383

Cash, Cash Equivalents and Sh_3

Cash, Cash Equivalents and Short-Term Investments (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Cash and Cash Equivalents [Abstract]
Average amount required to be held with Federal Reserve Bank	$ 8.2	$ 5.9
Aggregate reserves	$ 48	$ 40

Investment Securities (Summary

Investment Securities (Summary of Available-for-sale and Held-to-maturity Securities) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
AFS, debt securities, amortized cost	$ 515,250	$ 546,986
AFS, debt securities, gross unrealized gains	305	568
AFS, debt securities, gross unrealized losses	12,762	8,412
AFS, debt securities, estimated fair value	502,793	539,142
AFS, equity securities, amortized cost		978
AFS, equity securities, gross unrealized gains		13
AFS, equity securities, gross unrealized losses		9
AFS, equity securities, estimated fair value		982
Investment securities available-for-sale
AFS, amortized cost		547,964
AFS, gross unrealized gains		581
AFS, gross unrealized losses		8,421
AFS, estimated fair value		540,124
Investment securities held-to-maturity
HTM, amortized Cost	114,776	109,730
HTM, gross unrealized gains	32	159
HTM, gross unrealized losses	1,978	1,366
HTM, estimated fair value	112,830	108,523
Equity securities, amortized cost	4,207
Equity securities held-for-trading	4,207	0
GSE debentures
Debt Securities, Available-for-sale [Line Items]
AFS, debt securities, amortized cost	184,072	151,483
AFS, debt securities, gross unrealized gains	99	70
AFS, debt securities, gross unrealized losses	3,092	1,629
AFS, debt securities, estimated fair value	181,079	149,924
Investment securities held-to-maturity
HTM, amortized Cost	50,546	41,612
HTM, gross unrealized gains	22	0
HTM, gross unrealized losses	967	811
HTM, estimated fair value	49,601	40,801
GSE CMOs
Debt Securities, Available-for-sale [Line Items]
AFS, debt securities, amortized cost	107,363	131,082
AFS, debt securities, gross unrealized gains	17	27
AFS, debt securities, gross unrealized losses	4,250	4,087
AFS, debt securities, estimated fair value	103,130	127,022
GSE MBSs
Debt Securities, Available-for-sale [Line Items]
AFS, debt securities, amortized cost	169,334	191,281
AFS, debt securities, gross unrealized gains	124	354
AFS, debt securities, gross unrealized losses	4,369	2,322
AFS, debt securities, estimated fair value	165,089	189,313
Investment securities held-to-maturity
HTM, amortized Cost	11,426	13,923
HTM, gross unrealized gains	0	0
HTM, gross unrealized losses	295	218
HTM, estimated fair value	11,131	13,705
SBA commercial loan asset-backed securities
Debt Securities, Available-for-sale [Line Items]
AFS, debt securities, amortized cost	51	73
AFS, debt securities, gross unrealized gains	0	0
AFS, debt securities, gross unrealized losses	0	1
AFS, debt securities, estimated fair value	51	72
Municipal obligations
Investment securities held-to-maturity
HTM, amortized Cost	52,300	53,700
HTM, gross unrealized gains	10	159
HTM, gross unrealized losses	716	337
HTM, estimated fair value	51,598	53,517
Corporate debt obligations
Debt Securities, Available-for-sale [Line Items]
AFS, debt securities, amortized cost	40,618	62,811
AFS, debt securities, gross unrealized gains	0	110
AFS, debt securities, gross unrealized losses	910	238
AFS, debt securities, estimated fair value	39,708	62,683
U.S. treasury bonds
Debt Securities, Available-for-sale [Line Items]
AFS, debt securities, amortized cost	13,812	8,785
AFS, debt securities, gross unrealized gains	65	7
AFS, debt securities, gross unrealized losses	141	62
AFS, debt securities, estimated fair value	13,736	8,730
Trust preferred securities
Debt Securities, Available-for-sale [Line Items]
AFS, debt securities, amortized cost		1,471
AFS, debt securities, gross unrealized gains		0
AFS, debt securities, gross unrealized losses		73
AFS, debt securities, estimated fair value		1,398
Foreign government obligations
Investment securities held-to-maturity
HTM, amortized Cost	500	500
HTM, gross unrealized gains	0	0
HTM, gross unrealized losses	0	0
HTM, estimated fair value	$ 500	$ 500

Investment Securities (Other-Th

Investment Securities (Other-Than-Temporary Impairment) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt securities, available for sale:
Less than twelve months, estimated fair value	$ 61,213
Less than twelve months, unrealized losses	434
Twelve months or longer, estimated fair value	405,458
Twelve months or longer, unrealized losses	12,328
Total, fair value	466,671
Total, unrealized losses	12,762
Investment securities available-for-sale
Less than twelve months, estimated fair value		$ 254,035
Less than twelve months, unrealized losses		2,266
Twelve months or longer, estimated fair value		215,168
Twelve months or longer, unrealized losses		6,155
Estimated Fair Value		469,203
Total, unrealized losses		8,421
Investment securities held-to-maturity
Less than twelve months, estimated fair value	14,813	59,132
Less than twelve months, unrealized losses	107	531
Twelve months or longer, estimated fair value	87,291	33,790
Twelve months or longer, unrealized losses	1,871	835
Total, estimated fair value	102,104	92,922
Total, unrealized losses	1,978	1,366
Available-for-sale Securities and Held-to-maturity Securities [Abstract] (Deprecated 2018-01-31)
Less Than Twelve Months, Estimated Fair Value	76,026	313,167
Less Than Twelve Months, Unrealized Losses	541	2,797
Twelve Months or Longer, Estimated Fair Value	492,749	248,958
Twelve Months or Longer, Unrealized Losses	14,199	6,990
Total, Estimated Fair Value	568,775	562,125
Total, Unrealized Losses	14,740	9,787
GSE debentures
Debt securities, available for sale:
Less than twelve months, estimated fair value	25,780
Less than twelve months, unrealized losses	191
Twelve months or longer, estimated fair value	130,284
Twelve months or longer, unrealized losses	2,901
Total, fair value	156,064
Total, unrealized losses	3,092
Investment securities available-for-sale
Less than twelve months, estimated fair value		120,409
Less than twelve months, unrealized losses		1,263
Twelve months or longer, estimated fair value		12,481
Twelve months or longer, unrealized losses		366
Estimated Fair Value		132,890
Total, unrealized losses		1,629
Investment securities held-to-maturity
Less than twelve months, estimated fair value	0	26,594
Less than twelve months, unrealized losses	0	281
Twelve months or longer, estimated fair value	40,653	14,208
Twelve months or longer, unrealized losses	967	530
Total, estimated fair value	40,653	40,802
Total, unrealized losses	967	811
GSE CMOs
Debt securities, available for sale:
Less than twelve months, estimated fair value	0
Less than twelve months, unrealized losses	0
Twelve months or longer, estimated fair value	102,630
Twelve months or longer, unrealized losses	4,250
Total, fair value	102,630
Total, unrealized losses	4,250
Investment securities available-for-sale
Less than twelve months, estimated fair value		2,862
Less than twelve months, unrealized losses		34
Twelve months or longer, estimated fair value		123,548
Twelve months or longer, unrealized losses		4,053
Estimated Fair Value		126,410
Total, unrealized losses		4,087
GSE MBSs
Debt securities, available for sale:
Less than twelve months, estimated fair value	21,487
Less than twelve months, unrealized losses	113
Twelve months or longer, estimated fair value	138,051
Twelve months or longer, unrealized losses	4,256
Total, fair value	159,538
Total, unrealized losses	4,369
Investment securities available-for-sale
Less than twelve months, estimated fair value		94,985
Less than twelve months, unrealized losses		753
Twelve months or longer, estimated fair value		74,782
Twelve months or longer, unrealized losses		1,569
Estimated Fair Value		169,767
Total, unrealized losses		2,322
Investment securities held-to-maturity
Less than twelve months, estimated fair value	0	1,996
Less than twelve months, unrealized losses	0	15
Twelve months or longer, estimated fair value	11,080	11,674
Twelve months or longer, unrealized losses	295	203
Total, estimated fair value	11,080	13,670
Total, unrealized losses	295	218
SBA commercial loan asset-backed securities
Debt securities, available for sale:
Less than twelve months, estimated fair value	0
Less than twelve months, unrealized losses	0
Twelve months or longer, estimated fair value	51
Twelve months or longer, unrealized losses	0
Total, fair value	51
Total, unrealized losses	0
Investment securities available-for-sale
Less than twelve months, estimated fair value		34
Less than twelve months, unrealized losses		0
Twelve months or longer, estimated fair value		33
Twelve months or longer, unrealized losses		1
Estimated Fair Value		67
Total, unrealized losses		1
Corporate debt obligations
Debt securities, available for sale:
Less than twelve months, estimated fair value	10,019
Less than twelve months, unrealized losses	93
Twelve months or longer, estimated fair value	29,689
Twelve months or longer, unrealized losses	817
Total, fair value	39,708
Total, unrealized losses	910
Investment securities available-for-sale
Less than twelve months, estimated fair value		30,978
Less than twelve months, unrealized losses		154
Twelve months or longer, estimated fair value		2,423
Twelve months or longer, unrealized losses		84
Estimated Fair Value		33,401
Total, unrealized losses		238
U.S. treasury bonds
Debt securities, available for sale:
Less than twelve months, estimated fair value	3,927
Less than twelve months, unrealized losses	37
Twelve months or longer, estimated fair value	4,753
Twelve months or longer, unrealized losses	104
Total, fair value	8,680
Total, unrealized losses	141
Investment securities available-for-sale
Less than twelve months, estimated fair value		4,767
Less than twelve months, unrealized losses		62
Twelve months or longer, estimated fair value		0
Twelve months or longer, unrealized losses		0
Estimated Fair Value		4,767
Total, unrealized losses		62
Trust preferred securities
Investment securities available-for-sale
Less than twelve months, estimated fair value		0
Less than twelve months, unrealized losses		0
Twelve months or longer, estimated fair value		1,398
Twelve months or longer, unrealized losses		73
Estimated Fair Value		1,398
Total, unrealized losses		73
Marketable equity securities
Investment securities available-for-sale
Less than twelve months, estimated fair value		0
Less than twelve months, unrealized losses		0
Twelve months or longer, estimated fair value		503
Twelve months or longer, unrealized losses		9
Estimated Fair Value		503
Total, unrealized losses		9
Municipal obligations
Investment securities held-to-maturity
Less than twelve months, estimated fair value	14,813	30,542
Less than twelve months, unrealized losses	107	235
Twelve months or longer, estimated fair value	35,058	7,408
Twelve months or longer, unrealized losses	609	102
Total, estimated fair value	49,871	37,950
Total, unrealized losses	716	337
Foreign government obligations
Investment securities held-to-maturity
Less than twelve months, estimated fair value	0	0
Less than twelve months, unrealized losses	0	0
Twelve months or longer, estimated fair value	500	500
Twelve months or longer, unrealized losses	0	0
Total, estimated fair value	500	500
Total, unrealized losses	$ 0	$ 0

Investment Securities (Portfoli

Investment Securities (Portfolio Maturities) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Available for Sale, Amortized Cost
Within 1 year	$ 12,041	$ 23,612
After 1 year through 5 years	195,701	142,772
After 5 years through 10 years	115,665	136,746
Over 10 years	191,843	243,856
AFS, debt securities, amortized cost	515,250	546,986
Available for Sale, Estimated Fair Value
Within 1 year	12,007	23,652
After 1 year through 5 years	192,692	142,029
After 5 years through 10 years	112,819	134,978
Over 10 years	185,275	238,483
Total	$ 502,793	$ 539,142
Available for Sale, Weighted Average Rate
Within 1 year (as a percent)	2.03%	2.27%
After 1 year through 5 years (as a percent)	2.14%	2.05%
After 5 years through 10 years (as a percent)	2.18%	2.06%
Over 10 years (as a percent)	2.17%	2.06%
Total (as a percent)	2.16%	2.07%
Held-to-Maturity, Amortized Cost
Within 1 year	$ 7,640	$ 918
After 1 year through 5 years	72,735	58,335
After 5 years through 10 years	23,025	36,589
Over 10 years	11,376	13,888
Total	114,776	109,730
Held-to-Maturity, Estimated Fair Value
Within 1 year	7,618	916
After 1 year through 5 years	71,492	57,939
After 5 years through 10 years	22,640	35,998
Over 10 years	11,080	13,670
Total	$ 112,830	$ 108,523
Held-to-Maturity, Weighted Average Rate
Within 1 year (as a percent)	1.17%	0.78%
After 1 year through 5 years (as a percent)	1.84%	1.74%
After 5 years through 10 years (as a percent)	2.20%	1.79%
Over 10 years (as a percent)	2.13%	1.98%
Total (as a percent)	1.89%	1.78%

Investment Securities (Security

Investment Securities (Security Sales) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Securities, Available-for-sale [Line Items]
Proceeds from sales	$ 22,210	$ 0	$ 0
Gross gains from sales	1,472	11,612
Gross losses from sales	(68)	(219)
Gain on sales of securities, net	1,404	11,393
Proceeds from sales of debt securities
Debt Securities, Available-for-sale [Line Items]
Proceeds from sales	20,000	0
Proceeds from sales of marketable and restricted equity securities
Debt Securities, Available-for-sale [Line Items]
Proceeds from sales	$ 2,700	$ 11,393

Investment Securities (Narrativ

Investment Securities (Narrative) (Details)	Mar. 06, 2018USD ($)shares	Jul. 26, 2017USD ($)$ / sharesshares	Mar. 31, 2018USD ($)	Jul. 30, 2017USD ($)$ / sharesshares	Mar. 31, 2018shares	Mar. 31, 2017USD ($)	Dec. 31, 2018USD ($)securityshares	Dec. 31, 2017USD ($)security	Dec. 31, 2016USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2017shares	Feb. 03, 2017$ / sharesshares
Investment [Line Items]
AFS, debt securities, estimated fair value							$ 502,793,000	$ 539,142,000
Debt securities, unrealized gain (loss)							(12,500,000)
AFS, estimated fair value								540,124,000
Net unrealized gain (loss)								$ (7,800,000)
AFS, debt securities, unrealized loss position							$ 466,671,000
Percentage of securities in unrealized loss positions, available-for-sale securities							92.80%	86.90%
AFS, debt securities, unrealized loss position, accumulated loss							$ 12,762,000
AFS, unrealized loss position								$ 469,203,000
AFS, unrealized loss position, gross unrealized losses								8,421,000
Equity securities held-for-trading							$ 4,207,000	0
Number of equity securities FVNI | security							3
AFS, equity securities, estimated fair value								$ 982,000
Number of AFS equity securities | security								2
Investment securities held to maturity, fair value							$ 112,830,000	$ 108,523,000
Net unrealized gain (loss), held-to-maturity securities							(1,900,000)	(1,200,000)
Gross unrealized losses, fair value, held-to-maturity securities							$ 102,104,000	$ 92,922,000
Percentage of securities in unrealized loss positions, held-to-maturity securities							90.50%	85.60%
HTM, gross unrealized losses							$ 1,978,000	$ 1,366,000
Purchases of investment securities held-to-maturity							8,915,000	26,873,000	$ 36,167,000
Investment securities held-to-maturity							114,776,000	109,730,000
Estimated fair value of debt securities have right to call or prepay the obligations							19,100,000	58,800,000
Estimated fair value of debt securities have right to call or prepay the obligations, scheduled maturities of after one year through five years							8,400,000	32,700,000
Estimated fair value of debt securities have right to call or prepay the obligations, scheduled maturities after five years through ten years							10,700,000	25,200,000
Estimated fair value of debt securities have right to call or prepay the obligations, scheduled maturities of which is after 10 years							0	900,000
Gain on sales of securities, net							$ 1,404,000	11,393,000
Community Bank Systems, Inc.
Investment [Line Items]
Gain on sales of securities, net						$ 11,400,000
Community Bank Systems, Inc. | Brookline Bank
Investment [Line Items]
Cash received per share at exchange (in dollars per share) | $ / shares												$ 319.04
Number of acquirer shares received per acquiree shares held at exchange (in shares) | shares												14.876
Daily authorized amount of shares that can be sold (in shares) | shares												5,071
Investment owned cash proceeds from settlement	$ 600,000
Investment owned shares received form settlement | shares	11,303
Investment owned shares sold | shares	11,303
Gain (loss) on sale of investments	$ 600,000
Savings Bank Life Insurance
Investment [Line Items]
Proceeds from investments		$ 265,500		$ 265,500
Northeast Retirement Services | Brookline Bank
Investment [Line Items]
Number of shares held as investment | shares							9,721					9,721
Longwood Securities | Brookline Bank
Investment [Line Items]
Investment owned shares sold | shares					3
Investment owned										$ 1,500,000
Gain (loss) on sale of investments			$ (100,000)
GSE debt securities excluding specified securities
Investment [Line Items]
AFS, debt securities, estimated fair value							$ 20,600,000	23,700,000
GSE debentures
Investment [Line Items]
AFS, debt securities, estimated fair value							181,079,000	149,924,000
Debt securities, unrealized gain (loss)							$ (3,000,000)	$ (1,600,000)
Number of securities | security							60	48
Number of securities in unrealized loss positions | security							51	43
Payments to acquired AFS debt securities							$ 33,900,000	$ 54,200,000
Investment securities held to maturity, fair value							49,601,000	40,801,000
Net unrealized gain (loss), held-to-maturity securities							(900,000)	(800,000)
Gross unrealized losses, fair value, held-to-maturity securities							49,600,000	40,800,000
HTM, gross unrealized losses							$ 967,000	$ 811,000
Number of securities | security							17	14
Purchases of investment securities held-to-maturity							$ 8,900,000	$ 26,900,000
Number of securities in an unrealized loss position | security							14
Investment securities held-to-maturity							$ 50,546,000	41,612,000
GSE CMOs
Investment [Line Items]
AFS, debt securities, estimated fair value							103,100,000	127,000,000
Debt securities, unrealized gain (loss)							$ (4,200,000)	$ (4,100,000)
Number of securities | security							61	62
Number of securities in unrealized loss positions | security							46	47
Payments to acquired AFS debt securities							$ 0	$ 0
GSE mortgage-related securities
Investment [Line Items]
AFS, debt securities, estimated fair value							165,100,000	189,300,000
Debt securities, unrealized gain (loss)							$ (4,200,000)	$ (2,000,000)
Number of securities | security							165	194
Number of securities in unrealized loss positions | security							93	82
Payments to acquired AFS debt securities							$ 15,200,000	$ 18,300,000
SBA commercial loan asset-backed securities
Investment [Line Items]
AFS, debt securities, estimated fair value							$ 51,000	$ 72,000
Number of securities | security							4	5
Number of securities in unrealized loss positions | security							4	4
Corporate debt obligations
Investment [Line Items]
AFS, debt securities, estimated fair value							$ 39,708,000	$ 62,683,000
Debt securities, unrealized gain (loss)							$ (900,000)	$ (100,000)
Number of securities | security							11	19
Number of securities in unrealized loss positions | security								9
Payments to acquired AFS debt securities							$ 0	$ 14,500,000
U.S. Treasury bonds
Investment [Line Items]
AFS, debt securities, estimated fair value							13,700,000	8,700,000
Debt securities, unrealized gain (loss)							$ 100,000	$ (100,000)
Number of securities | security							7	2
Payments to acquired AFS debt securities							$ 24,700,000	$ 4,000,000
Trust preferred securities
Investment [Line Items]
AFS, debt securities, estimated fair value								1,398,000
Debt securities, unrealized gain (loss)								$ (100,000)
Number of securities | security								2
GSE MBSs
Investment [Line Items]
AFS, debt securities, estimated fair value							165,089,000	$ 189,313,000
Investment securities held to maturity, fair value							11,131,000	13,705,000
Net unrealized gain (loss), held-to-maturity securities							(300,000)	(200,000)
Gross unrealized losses, fair value, held-to-maturity securities							11,100,000	13,700,000
HTM, gross unrealized losses							$ 295,000	$ 218,000
Number of securities | security							11	11
Purchases of investment securities held-to-maturity							$ 0	$ 0
Number of securities in an unrealized loss position | security							8	8
Investment securities held-to-maturity							$ 11,426,000	$ 13,923,000
Municipal obligations
Investment [Line Items]
Investment securities held to maturity, fair value							51,598,000	53,517,000
Gross unrealized losses, fair value, held-to-maturity securities							51,600,000	53,500,000
HTM, gross unrealized losses							$ 716,000	$ 337,000
Number of securities | security							98	100
Purchases of investment securities held-to-maturity							$ 0	$ 0
Number of securities in an unrealized loss position | security							94	69
Investment securities held-to-maturity							$ 52,300,000	$ 53,700,000
Foreign government obligations
Investment [Line Items]
Investment securities held to maturity, fair value							500,000	500,000
Gross unrealized losses, fair value, held-to-maturity securities							500,000	500,000
HTM, gross unrealized losses							$ 0	$ 0
Number of securities | security							1	1
Purchases of investment securities held-to-maturity							$ 0	$ 0
Investment securities held-to-maturity							500,000	500,000
Collateral Pledged
Investment [Line Items]
Available for sale securities pledged as collateral							$ 442,500,000	$ 431,200,000
Common Class A | Savings Bank Life Insurance
Investment [Line Items]
Number of shares held as investment | shares		1		1							1
Share price (in usd per share) | $ / shares		$ 500		$ 500
Common Class B | Savings Bank Life Insurance
Investment [Line Items]
Number of shares held as investment | shares		2,070		2,070							2,070
Share price (in usd per share) | $ / shares		$ 128		$ 128

Restricted Equity Securities (I

Restricted Equity Securities (Investments in Restricted Equity Securities) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Restricted equity securities
Restricted equity securities	$ 61,751	$ 59,369
FHLBB stock
Restricted equity securities
Restricted equity securities	43,655	42,427
FRB stock
Restricted equity securities
Restricted equity securities	17,995	16,842
Other restricted equity securities
Restricted equity securities
Restricted equity securities	$ 101	$ 100

Restricted Equity Securities (N

Restricted Equity Securities (Narrative) (Details) - USD ($)	Jul. 26, 2017	Jul. 30, 2017	Dec. 31, 2018	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Feb. 03, 2017
Investment [Line Items]
Gain on sales of securities, net						$ 1,404,000	$ 11,393,000
FHLBB stock
Investment [Line Items]
Dividend rate (as a percent)			5.87%	4.99%			4.14%
Northeast Retirement Services | Brookline Bank
Investment [Line Items]
Number of shares held as investment			9,721			9,721			9,721
Shares held as investment at cost			$ 122,000			$ 122,000
Community Bank Systems, Inc.
Investment [Line Items]
Gain on sales of securities, net					$ 11,400,000
Community Bank Systems, Inc. | Brookline Bank
Investment [Line Items]
Cash received per share at exchange (in dollars per share)									$ 319.04
Number of acquirer shares received per acquiree shares held at exchange (in shares)									14.876
Daily authorized amount of shares that can be sold (in shares)									5,071
Savings Bank Life Insurance
Investment [Line Items]
Proceeds from investments	$ 265,500	$ 265,500
Savings Bank Life Insurance | Common Class A
Investment [Line Items]
Number of shares held as investment	1	1						1
Share price (in usd per share)	$ 500	$ 500
Savings Bank Life Insurance | Common Class B
Investment [Line Items]
Number of shares held as investment	2,070	2,070						2,070
Share price (in usd per share)	$ 128	$ 128

Loans and Leases (Summary of Lo

Loans and Leases (Summary of Loan and Lease Balances and Weighted Average Coupon Rates) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Originated loans	$ 5,909,109	$ 5,490,622
Originated, Weighted Average Coupon (as a percent)	5.13%	4.65%
Acquired loans	$ 394,407	$ 240,057
Acquired, Weighted Average Coupon (as a percent)	4.83%	4.49%
Total loans and leases	$ 6,303,516	$ 5,730,679
Total, Weighted Average Coupon (as a percent)	5.11%	4.64%
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 2,330,725	$ 2,174,969
Multi-family mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	847,711	760,670
Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	173,300	140,138
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	736,418	705,004
Equipment financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	982,089	866,488
Condominium association
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	50,451	52,619
Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	782,968	660,065
Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	376,484	355,954
Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	23,370	14,772
Commercial real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Originated loans	$ 3,159,855	$ 2,945,451
Originated, Weighted Average Coupon (as a percent)	4.63%	4.17%
Acquired loans	$ 191,881	$ 130,326
Acquired, Weighted Average Coupon (as a percent)	4.85%	4.39%
Total loans and leases	$ 3,351,736	$ 3,075,777
Total, Weighted Average Coupon (as a percent)	4.64%	4.18%
Commercial real estate loans | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Originated loans	$ 2,208,904	$ 2,069,392
Originated, Weighted Average Coupon (as a percent)	4.61%	4.17%
Acquired loans	$ 121,821	$ 105,577
Acquired, Weighted Average Coupon (as a percent)	4.62%	4.37%
Total loans and leases	$ 2,330,725	$ 2,174,969
Total, Weighted Average Coupon (as a percent)	4.61%	4.18%
Commercial real estate loans | Multi-family mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Originated loans	$ 799,813	$ 735,921
Originated, Weighted Average Coupon (as a percent)	4.51%	4.09%
Acquired loans	$ 47,898	$ 24,749
Acquired, Weighted Average Coupon (as a percent)	4.58%	4.48%
Total loans and leases	$ 847,711	$ 760,670
Total, Weighted Average Coupon (as a percent)	4.51%	4.10%
Commercial real estate loans | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Originated loans	$ 151,138	$ 140,138
Originated, Weighted Average Coupon (as a percent)	5.62%	4.58%
Acquired loans	$ 22,162	$ 0
Acquired, Weighted Average Coupon (as a percent)	6.74%	0.00%
Total loans and leases	$ 173,300	$ 140,138
Total, Weighted Average Coupon (as a percent)	5.76%	4.58%
Commercial loans and leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Originated loans	$ 1,741,921	$ 1,611,418
Originated, Weighted Average Coupon (as a percent)	6.44%	5.92%
Acquired loans	$ 27,037	$ 12,693
Acquired, Weighted Average Coupon (as a percent)	5.46%	5.82%
Total loans and leases	$ 1,768,958	$ 1,624,111
Total, Weighted Average Coupon (as a percent)	6.43%	5.92%
Commercial loans and leases | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Originated loans	$ 712,630	$ 696,825
Originated, Weighted Average Coupon (as a percent)	4.96%	4.35%
Acquired loans	$ 23,788	$ 8,179
Acquired, Weighted Average Coupon (as a percent)	5.39%	5.77%
Total loans and leases	$ 736,418	$ 705,004
Total, Weighted Average Coupon (as a percent)	4.97%	4.37%
Commercial loans and leases | Equipment financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Originated loans	$ 978,840	$ 861,974
Originated, Weighted Average Coupon (as a percent)	7.61%	7.28%
Acquired loans	$ 3,249	$ 4,514
Acquired, Weighted Average Coupon (as a percent)	5.97%	5.92%
Total loans and leases	$ 982,089	$ 866,488
Total, Weighted Average Coupon (as a percent)	7.60%	7.27%
Commercial loans and leases | Condominium association
Accounts, Notes, Loans and Financing Receivable [Line Items]
Originated loans	$ 50,451	$ 52,619
Originated, Weighted Average Coupon (as a percent)	4.70%	4.49%
Acquired loans	$ 0	$ 0
Acquired, Weighted Average Coupon (as a percent)	0.00%	0.00%
Total loans and leases	$ 50,451	$ 52,619
Total, Weighted Average Coupon (as a percent)	4.70%	4.49%
Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Originated loans	$ 1,007,333	$ 933,753
Originated, Weighted Average Coupon (as a percent)	4.44%	3.95%
Acquired loans	$ 175,489	$ 97,038
Acquired, Weighted Average Coupon (as a percent)	4.70%	4.44%
Total loans and leases	$ 1,182,822	$ 1,030,791
Total, Weighted Average Coupon (as a percent)	4.48%	4.00%
Consumer loans | Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Originated loans	$ 653,059	$ 604,897
Originated, Weighted Average Coupon (as a percent)	4.09%	3.81%
Acquired loans	$ 129,909	$ 55,168
Acquired, Weighted Average Coupon (as a percent)	4.45%	4.28%
Total loans and leases	$ 782,968	$ 660,065
Total, Weighted Average Coupon (as a percent)	4.15%	3.85%
Consumer loans | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Originated loans	$ 331,014	$ 314,189
Originated, Weighted Average Coupon (as a percent)	5.05%	4.16%
Acquired loans	$ 45,470	$ 41,765
Acquired, Weighted Average Coupon (as a percent)	5.39%	4.62%
Total loans and leases	$ 376,484	$ 355,954
Total, Weighted Average Coupon (as a percent)	5.09%	4.21%
Consumer loans | Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Originated loans	$ 23,260	$ 14,667
Originated, Weighted Average Coupon (as a percent)	5.55%	5.51%
Acquired loans	$ 110	$ 105
Acquired, Weighted Average Coupon (as a percent)	17.81%	18.00%
Total loans and leases	$ 23,370	$ 14,772
Total, Weighted Average Coupon (as a percent)	5.61%	5.60%

Loans and Leases (Accretable Yi

Loans and Leases (Accretable Yield for the Acquired Loan Portfolio) (Details) - Acquired - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Summarized activity in accretable yield for the acquired loan portfolio
Balance at beginning of year	$ 10,522	$ 14,353	$ 20,796
Accretion	(4,117)	(7,801)	(6,781)
Reclassification from nonaccretable difference as a result from changes in expected cash flows	1,500	3,970	300
Balance at end of year	$ 7,905	$ 10,522	$ 14,353

Loans and Leases (Loans and Adv

Loans and Leases (Loans and Advances to Directors, Executive Officers and Their Affiliates) (Details) - Directors, executive officers and their affiliates - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Change in the total amounts of loans and advances, all of which were performing
Balance at beginning of year	$ 47,941	$ 43,458
New loans granted during the year	2,842	13,554
Advances on lines of credit	193	473
Repayments	(4,205)	(9,544)
Balance at end of year	$ 46,771	$ 47,941

Loans and Leases (Narrative) (D

Loans and Leases (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unamortized deferred loan origination fees and costs	$ 15,600	$ 15,500
Percentage of loans to aggregate outstanding amount in the greater New York/New Jersey Metropolitan area and northeastern states	26.80%	28.00%
Percentage of loans to aggregate outstanding amount in Other areas of the United States	73.20%	72.00%
Loans and leases pledged as collateral	$ 3,000,000	$ 2,300,000
Directors, executive officers and their affiliates
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded commitments on extensions of credit	5,900	15,700
Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Reclassification from nonaccretable difference as a result from changes in expected cash flows	$ 1,500	$ 3,970	$ 300

Allowance for Loan and Lease _3

Allowance for Loan and Lease Losses (Summary of Changes in the Allowance for Loan and Lease Losses and Recorded Investments by Portfolio Segment) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Changes in allowance for loan losses
Balance at the beginning of the period				$ 58,592				$ 53,666	$ 58,592	$ 53,666	$ 56,739
Charge-offs									(7,228)	(15,811)	(14,667)
Recoveries									2,577	1,953	1,392
Provision for loan and lease losses									4,751	18,784	10,202
Balance at the end of the period	$ 58,692				$ 58,592				58,692	58,592	53,666
Provisions for credit losses
Total provision for loan and lease losses									4,751	18,784	10,202
Unfunded credit commitments									200	204	151
Total provision (credit) for credit losses	123	$ 2,717	$ 1,470	641	1,802	$ 2,911	$ 873	13,402	4,951	18,988	10,353
Commercial Real Estate
Changes in allowance for loan losses
Balance at the beginning of the period				27,112				27,645	27,112	27,645	30,151
Charge-offs									(103)	(494)	(2,169)
Recoveries									0	476	0
Provision for loan and lease losses									1,178	(515)	(337)
Balance at the end of the period	28,187				27,112				28,187	27,112	27,645
Provisions for credit losses
Total provision for loan and lease losses									1,178	(515)	(337)
Commercial
Changes in allowance for loan losses
Balance at the beginning of the period				26,333				20,906	26,333	20,906	22,018
Charge-offs									(6,585)	(14,914)	(10,516)
Recoveries									2,287	1,158	642
Provision for loan and lease losses									3,248	19,183	8,762
Balance at the end of the period	25,283				26,333				25,283	26,333	20,906
Provisions for credit losses
Total provision for loan and lease losses									3,248	19,183	8,762
Consumer
Changes in allowance for loan losses
Balance at the beginning of the period				$ 5,147				$ 5,115	5,147	5,115	4,570
Charge-offs									(540)	(403)	(1,982)
Recoveries									290	319	750
Provision for loan and lease losses									325	116	1,777
Balance at the end of the period	$ 5,222				$ 5,147				5,222	5,147	5,115
Provisions for credit losses
Total provision for loan and lease losses									325	116	1,777
Originated
Changes in allowance for loan losses
Provision for loan and lease losses									4,509	18,829	8,982
Provisions for credit losses
Total provision for loan and lease losses									4,509	18,829	8,982
Unfunded credit commitments									200	204	151
Total provision (credit) for credit losses									4,709	19,033	9,133
Originated | Commercial Real Estate
Changes in allowance for loan losses
Provision for loan and lease losses									254	(343)	(750)
Provisions for credit losses
Total provision for loan and lease losses									254	(343)	(750)
Originated | Commercial
Changes in allowance for loan losses
Provision for loan and lease losses									3,699	18,899	8,469
Provisions for credit losses
Total provision for loan and lease losses									3,699	18,899	8,469
Originated | Consumer
Changes in allowance for loan losses
Provision for loan and lease losses									556	273	1,263
Provisions for credit losses
Total provision for loan and lease losses									556	273	1,263
Acquired
Changes in allowance for loan losses
Provision for loan and lease losses									242	(45)	1,220
Provisions for credit losses
Total provision for loan and lease losses									242	(45)	1,220
Unfunded credit commitments									0	0	0
Total provision (credit) for credit losses									242	(45)	1,220
Acquired | Commercial Real Estate
Changes in allowance for loan losses
Provision for loan and lease losses									924	(172)	413
Provisions for credit losses
Total provision for loan and lease losses									924	(172)	413
Acquired | Commercial
Changes in allowance for loan losses
Provision for loan and lease losses									(451)	284	293
Provisions for credit losses
Total provision for loan and lease losses									(451)	284	293
Acquired | Consumer
Changes in allowance for loan losses
Provision for loan and lease losses									(231)	(157)	514
Provisions for credit losses
Total provision for loan and lease losses									$ (231)	$ (157)	$ 514

Allowance for Loan and Lease _4

Allowance for Loan and Lease Losses (Credit Quality Information) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Credit Quality Information
Recorded investment	$ 6,303,516	$ 5,730,679
Originated
Credit Quality Information
Recorded investment	5,909,109	5,490,622
Acquired
Credit Quality Information
Recorded investment	394,407	240,057
Commercial real estate
Credit Quality Information
Recorded investment	2,330,725	2,174,969
Commercial real estate | Originated
Credit Quality Information
Recorded investment	2,208,904	2,069,392
Commercial real estate | Acquired
Credit Quality Information
Recorded investment	121,821	105,577
Commercial real estate | Pass | Originated
Credit Quality Information
Recorded investment	2,198,377	2,054,376
Commercial real estate | Pass | Acquired
Credit Quality Information
Recorded investment	111,919	94,244
Commercial real estate | OAEM | Originated
Credit Quality Information
Recorded investment	6,096	8,889
Commercial real estate | OAEM | Acquired
Credit Quality Information
Recorded investment	626	9,839
Commercial real estate | Substandard | Originated
Credit Quality Information
Recorded investment	4,431	5,926
Commercial real estate | Substandard | Acquired
Credit Quality Information
Recorded investment	9,276	1,494
Commercial real estate | Doubtful | Originated
Credit Quality Information
Recorded investment	0	201
Multi-family mortgage
Credit Quality Information
Recorded investment	847,711	760,670
Multi-family mortgage | Originated
Credit Quality Information
Recorded investment	799,813	735,921
Multi-family mortgage | Acquired
Credit Quality Information
Recorded investment	47,898	24,749
Multi-family mortgage | Pass | Originated
Credit Quality Information
Recorded investment	799,483	735,313
Multi-family mortgage | Pass | Acquired
Credit Quality Information
Recorded investment	47,715	24,459
Multi-family mortgage | OAEM | Originated
Credit Quality Information
Recorded investment	0	0
Multi-family mortgage | OAEM | Acquired
Credit Quality Information
Recorded investment	0	0
Multi-family mortgage | Substandard | Originated
Credit Quality Information
Recorded investment	330	608
Multi-family mortgage | Substandard | Acquired
Credit Quality Information
Recorded investment	183	290
Multi-family mortgage | Doubtful | Originated
Credit Quality Information
Recorded investment	0	0
Construction
Credit Quality Information
Recorded investment	173,300	140,138
Construction | Originated
Credit Quality Information
Recorded investment	151,138	140,138
Construction | Acquired
Credit Quality Information
Recorded investment	22,162	0
Construction | Pass | Originated
Credit Quality Information
Recorded investment	150,742	139,278
Construction | Pass | Acquired
Credit Quality Information
Recorded investment	22,162	0
Construction | OAEM | Originated
Credit Quality Information
Recorded investment	0	0
Construction | OAEM | Acquired
Credit Quality Information
Recorded investment	0	0
Construction | Substandard | Originated
Credit Quality Information
Recorded investment	396	860
Construction | Substandard | Acquired
Credit Quality Information
Recorded investment	0	0
Construction | Doubtful | Originated
Credit Quality Information
Recorded investment	0	0
Commercial
Credit Quality Information
Recorded investment	736,418	705,004
Commercial | Originated
Credit Quality Information
Recorded investment	712,630	696,825
Commercial | Acquired
Credit Quality Information
Recorded investment	23,788	8,179
Commercial | Pass | Originated
Credit Quality Information
Recorded investment	685,773	670,265
Commercial | Pass | Acquired
Credit Quality Information
Recorded investment	23,250	6,643
Commercial | OAEM | Originated
Credit Quality Information
Recorded investment	3,726	7,691
Commercial | OAEM | Acquired
Credit Quality Information
Recorded investment	236	265
Commercial | Substandard | Originated
Credit Quality Information
Recorded investment	22,870	17,681
Commercial | Substandard | Acquired
Credit Quality Information
Recorded investment	302	1,271
Commercial | Doubtful | Originated
Credit Quality Information
Recorded investment	261	1,188
Equipment financing
Credit Quality Information
Recorded investment	982,089	866,488
Equipment financing | Originated
Credit Quality Information
Recorded investment	978,840	861,974
Equipment financing | Acquired
Credit Quality Information
Recorded investment	3,249	4,514
Equipment financing | Pass | Originated
Credit Quality Information
Recorded investment	969,275	850,006
Equipment financing | Pass | Acquired
Credit Quality Information
Recorded investment	3,240	4,501
Equipment financing | OAEM | Originated
Credit Quality Information
Recorded investment	52	3,630
Equipment financing | OAEM | Acquired
Credit Quality Information
Recorded investment	0	0
Equipment financing | Substandard | Originated
Credit Quality Information
Recorded investment	6,895	5,012
Equipment financing | Substandard | Acquired
Credit Quality Information
Recorded investment	9	13
Equipment financing | Doubtful | Originated
Credit Quality Information
Recorded investment	2,618	3,326
Condominium association
Credit Quality Information
Recorded investment	50,451	52,619
Condominium association | Originated
Credit Quality Information
Recorded investment	50,451	52,619
Condominium association | Acquired
Credit Quality Information
Recorded investment	0	0
Condominium association | Pass | Originated
Credit Quality Information
Recorded investment	50,186	52,619
Condominium association | Pass | Acquired
Credit Quality Information
Recorded investment	0	0
Condominium association | OAEM | Originated
Credit Quality Information
Recorded investment	0	0
Condominium association | OAEM | Acquired
Credit Quality Information
Recorded investment	0	0
Condominium association | Substandard | Originated
Credit Quality Information
Recorded investment	265	0
Condominium association | Substandard | Acquired
Credit Quality Information
Recorded investment	0	0
Condominium association | Doubtful | Originated
Credit Quality Information
Recorded investment	0	0
Other consumer
Credit Quality Information
Recorded investment	23,370	14,772
Other consumer | Originated
Credit Quality Information
Recorded investment	23,260	14,667
Other consumer | Acquired
Credit Quality Information
Recorded investment	110	105
Other consumer | Pass | Originated
Credit Quality Information
Recorded investment	23,249	14,628
Other consumer | Pass | Acquired
Credit Quality Information
Recorded investment	110	104
Other consumer | OAEM | Originated
Credit Quality Information
Recorded investment	0	0
Other consumer | OAEM | Acquired
Credit Quality Information
Recorded investment	0	1
Other consumer | Substandard | Originated
Credit Quality Information
Recorded investment	11	39
Other consumer | Substandard | Acquired
Credit Quality Information
Recorded investment	0	0
Other consumer | Doubtful | Originated
Credit Quality Information
Recorded investment	0	0
Total
Credit Quality Information
Recorded investment		4,714,660
Total | Originated
Credit Quality Information
Recorded investment	4,925,036	4,571,536
Total | Acquired
Credit Quality Information
Recorded investment	219,028	143,124
Total | Pass
Credit Quality Information
Recorded investment	5,144,064
Total | Pass | Originated
Credit Quality Information
Recorded investment	4,877,085	4,516,485
Total | Pass | Acquired
Credit Quality Information
Recorded investment	208,396	129,951
Total | OAEM | Originated
Credit Quality Information
Recorded investment	9,874	20,210
Total | OAEM | Acquired
Credit Quality Information
Recorded investment	862	10,105
Total | Substandard | Originated
Credit Quality Information
Recorded investment	35,198	30,126
Total | Substandard | Acquired
Credit Quality Information
Recorded investment	9,770	3,068
Total | Doubtful | Originated
Credit Quality Information
Recorded investment	2,879	4,715
Residential mortgage
Credit Quality Information
Recorded investment	$ 782,968	$ 660,065
Percentage of loans to aggregate outstanding amount	100.00%	100.00%
Residential mortgage | Originated
Credit Quality Information
Recorded investment	$ 653,059	$ 604,897
Percentage of loans to aggregate outstanding amount	83.40%	91.60%
Residential mortgage | Acquired
Credit Quality Information
Recorded investment	$ 129,909	$ 55,168
Percentage of loans to aggregate outstanding amount	16.60%	8.40%
Residential mortgage | Loan-to-value ratio, less than 50% | Originated
Credit Quality Information
Recorded investment	$ 171,523	$ 153,373
Percentage of loans to aggregate outstanding amount	21.90%	23.20%
Residential mortgage | Loan-to-value ratio, less than 50% | Acquired
Credit Quality Information
Recorded investment	$ 36,752	$ 16,521
Percentage of loans to aggregate outstanding amount	4.60%	2.50%
Residential mortgage | Loan-to-value ratio, 50% - 69% | Originated
Credit Quality Information
Recorded investment	$ 287,337	$ 265,328
Percentage of loans to aggregate outstanding amount	36.70%	40.20%
Residential mortgage | Loan-to-value ratio, 50% - 69% | Acquired
Credit Quality Information
Recorded investment	$ 53,788	$ 19,182
Percentage of loans to aggregate outstanding amount	6.90%	2.90%
Residential mortgage | Loan-to-value ratio, 70% - 79% | Originated
Credit Quality Information
Recorded investment	$ 173,870	$ 168,272
Percentage of loans to aggregate outstanding amount	22.20%	25.50%
Residential mortgage | Loan-to-value ratio, 70% - 79% | Acquired
Credit Quality Information
Recorded investment	$ 26,510	$ 10,507
Percentage of loans to aggregate outstanding amount	3.40%	1.60%
Residential mortgage | Loan-to-value ratio, 80% and over | Originated
Credit Quality Information
Recorded investment	$ 19,030	$ 16,547
Percentage of loans to aggregate outstanding amount	2.40%	2.50%
Residential mortgage | Loan-to-value ratio, 80% and over | Acquired
Credit Quality Information
Recorded investment	$ 6,701	$ 7,893
Percentage of loans to aggregate outstanding amount	0.90%	1.20%
Residential mortgage | Data not available | Originated
Credit Quality Information
Recorded investment	$ 1,299	$ 1,377
Percentage of loans to aggregate outstanding amount	0.20%	0.20%
Residential mortgage | Data not available | Acquired
Credit Quality Information
Recorded investment	$ 6,158	$ 1,065
Percentage of loans to aggregate outstanding amount	0.80%	0.20%
Home equity
Credit Quality Information
Recorded investment	$ 376,484	$ 355,954
Percentage of loans to aggregate outstanding amount	100.00%	100.00%
Home equity | Originated
Credit Quality Information
Recorded investment	$ 331,014	$ 314,189
Percentage of loans to aggregate outstanding amount	87.90%	88.20%
Home equity | Acquired
Credit Quality Information
Recorded investment	$ 45,470	$ 41,765
Percentage of loans to aggregate outstanding amount	12.10%	11.80%
Home equity | Loan-to-value ratio, less than 50% | Originated
Credit Quality Information
Recorded investment	$ 142,534	$ 148,137
Percentage of loans to aggregate outstanding amount	37.90%	41.60%
Home equity | Loan-to-value ratio, less than 50% | Acquired
Credit Quality Information
Recorded investment	$ 24,705	$ 25,312
Percentage of loans to aggregate outstanding amount	6.60%	7.10%
Home equity | Loan-to-value ratio, 50% - 69% | Originated
Credit Quality Information
Recorded investment	$ 84,423	$ 75,099
Percentage of loans to aggregate outstanding amount	22.40%	21.10%
Home equity | Loan-to-value ratio, 50% - 69% | Acquired
Credit Quality Information
Recorded investment	$ 10,353	$ 13,883
Percentage of loans to aggregate outstanding amount	2.70%	3.90%
Home equity | Loan-to-value ratio, 70% - 79% | Originated
Credit Quality Information
Recorded investment	$ 73,898	$ 63,742
Percentage of loans to aggregate outstanding amount	19.60%	17.90%
Home equity | Loan-to-value ratio, 70% - 79% | Acquired
Credit Quality Information
Recorded investment	$ 1,000	$ 943
Percentage of loans to aggregate outstanding amount	0.30%	0.30%
Home equity | Loan-to-value ratio, 80% and over | Originated
Credit Quality Information
Recorded investment	$ 30,129	$ 27,122
Percentage of loans to aggregate outstanding amount	8.00%	7.60%
Home equity | Loan-to-value ratio, 80% and over | Acquired
Credit Quality Information
Recorded investment	$ 4,348	$ 582
Percentage of loans to aggregate outstanding amount	1.20%	0.20%
Home equity | Data not available | Originated
Credit Quality Information
Recorded investment	$ 30	$ 89
Percentage of loans to aggregate outstanding amount	0.00%	0.00%
Home equity | Data not available | Acquired
Credit Quality Information
Recorded investment	$ 5,064	$ 1,045
Percentage of loans to aggregate outstanding amount	1.30%	0.30%

Allowance for Loan and Lease _5

Allowance for Loan and Lease Losses (Foreclosed Residential Real Estate Property) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Recorded investment in mortgage loans collateralized by residential real estate property that are in the process of foreclosure	$ 121	$ 633

Allowance for Loan and Lease _6

Allowance for Loan and Lease Losses (Past Due Loans) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Age analysis of past due loans
Past Due	$ 45,450	$ 50,704
Current	6,258,066	5,679,975
Total Loans and Leases	6,303,516	5,730,679
Loans and Leases Past Due Greater Than 90 Days and Accruing	13,482	3,020
Nonaccrual Loans and Leases	24,097	27,272
Commercial real estate
Age analysis of past due loans
Total Loans and Leases	2,330,725	2,174,969
Multi-family mortgage
Age analysis of past due loans
Total Loans and Leases	847,711	760,670
Construction
Age analysis of past due loans
Total Loans and Leases	173,300	140,138
Commercial
Age analysis of past due loans
Total Loans and Leases	736,418	705,004
Equipment financing
Age analysis of past due loans
Total Loans and Leases	982,089	866,488
Condominium association
Age analysis of past due loans
Total Loans and Leases	50,451	52,619
Residential mortgage
Age analysis of past due loans
Total Loans and Leases	782,968	660,065
Home equity
Age analysis of past due loans
Total Loans and Leases	376,484	355,954
Other consumer
Age analysis of past due loans
Total Loans and Leases	23,370	14,772
Commercial real estate loans
Age analysis of past due loans
Total Loans and Leases	3,351,736	3,075,777
Commercial real estate loans | Commercial real estate
Age analysis of past due loans
Total Loans and Leases	2,330,725	2,174,969
Commercial real estate loans | Multi-family mortgage
Age analysis of past due loans
Total Loans and Leases	847,711	760,670
Commercial real estate loans | Construction
Age analysis of past due loans
Total Loans and Leases	173,300	140,138
Commercial loans and leases
Age analysis of past due loans
Total Loans and Leases	1,768,958	1,624,111
Commercial loans and leases | Commercial
Age analysis of past due loans
Total Loans and Leases	736,418	705,004
Commercial loans and leases | Equipment financing
Age analysis of past due loans
Total Loans and Leases	982,089	866,488
Commercial loans and leases | Condominium association
Age analysis of past due loans
Total Loans and Leases	50,451	52,619
Consumer loans
Age analysis of past due loans
Total Loans and Leases	1,182,822	1,030,791
Consumer loans | Residential mortgage
Age analysis of past due loans
Total Loans and Leases	782,968	660,065
Consumer loans | Home equity
Age analysis of past due loans
Total Loans and Leases	376,484	355,954
Consumer loans | Other consumer
Age analysis of past due loans
Total Loans and Leases	23,370	14,772
31-60 days past due
Age analysis of past due loans
Past Due	13,414	25,040
61-90 days past due
Age analysis of past due loans
Past Due	3,308	7,376
Greater than 90 days past due
Age analysis of past due loans
Past Due	28,728	18,288
Originated
Age analysis of past due loans
Past Due	31,789	44,811
Current	5,877,320	5,445,811
Total Loans and Leases	5,909,109	5,490,622
Loans and Leases Past Due Greater Than 90 Days and Accruing	2,252	225
Nonaccrual Loans and Leases	22,768	25,275
Originated | Commercial real estate
Age analysis of past due loans
Total Loans and Leases	2,208,904	2,069,392
Originated | Multi-family mortgage
Age analysis of past due loans
Total Loans and Leases	799,813	735,921
Originated | Construction
Age analysis of past due loans
Total Loans and Leases	151,138	140,138
Originated | Commercial
Age analysis of past due loans
Total Loans and Leases	712,630	696,825
Originated | Equipment financing
Age analysis of past due loans
Total Loans and Leases	978,840	861,974
Originated | Condominium association
Age analysis of past due loans
Total Loans and Leases	50,451	52,619
Originated | Residential mortgage
Age analysis of past due loans
Total Loans and Leases	653,059	604,897
Originated | Home equity
Age analysis of past due loans
Total Loans and Leases	331,014	314,189
Originated | Other consumer
Age analysis of past due loans
Total Loans and Leases	23,260	14,667
Originated | Commercial real estate loans
Age analysis of past due loans
Past Due	10,728	21,986
Current	3,149,127	2,923,465
Total Loans and Leases	3,159,855	2,945,451
Loans and Leases Past Due Greater Than 90 Days and Accruing	277	0
Nonaccrual Loans and Leases	4,532	4,650
Originated | Commercial real estate loans | Commercial real estate
Age analysis of past due loans
Past Due	8,997	5,528
Current	2,199,907	2,063,864
Total Loans and Leases	2,208,904	2,069,392
Loans and Leases Past Due Greater Than 90 Days and Accruing	277	0
Nonaccrual Loans and Leases	3,806	3,182
Originated | Commercial real estate loans | Multi-family mortgage
Age analysis of past due loans
Past Due	1,038	8,731
Current	798,775	727,190
Total Loans and Leases	799,813	735,921
Loans and Leases Past Due Greater Than 90 Days and Accruing	0	0
Nonaccrual Loans and Leases	330	608
Originated | Commercial real estate loans | Construction
Age analysis of past due loans
Past Due	693	7,727
Current	150,445	132,411
Total Loans and Leases	151,138	140,138
Loans and Leases Past Due Greater Than 90 Days and Accruing	0	0
Nonaccrual Loans and Leases	396	860
Originated | Commercial loans and leases
Age analysis of past due loans
Past Due	18,011	19,695
Current	1,723,910	1,591,723
Total Loans and Leases	1,741,921	1,611,418
Loans and Leases Past Due Greater Than 90 Days and Accruing	1,974	224
Nonaccrual Loans and Leases	16,186	18,471
Originated | Commercial loans and leases | Commercial
Age analysis of past due loans
Past Due	8,847	9,665
Current	703,783	687,160
Total Loans and Leases	712,630	696,825
Loans and Leases Past Due Greater Than 90 Days and Accruing	1,962	0
Nonaccrual Loans and Leases	6,421	10,365
Originated | Commercial loans and leases | Equipment financing
Age analysis of past due loans
Past Due	8,844	8,911
Current	969,996	853,063
Total Loans and Leases	978,840	861,974
Loans and Leases Past Due Greater Than 90 Days and Accruing	12	224
Nonaccrual Loans and Leases	9,500	8,106
Originated | Commercial loans and leases | Condominium association
Age analysis of past due loans
Past Due	320	1,119
Current	50,131	51,500
Total Loans and Leases	50,451	52,619
Loans and Leases Past Due Greater Than 90 Days and Accruing	0	0
Nonaccrual Loans and Leases	265	0
Originated | Consumer loans
Age analysis of past due loans
Past Due	3,050	3,130
Current	1,004,283	930,623
Total Loans and Leases	1,007,333	933,753
Loans and Leases Past Due Greater Than 90 Days and Accruing	1	1
Nonaccrual Loans and Leases	2,050	2,154
Originated | Consumer loans | Residential mortgage
Age analysis of past due loans
Past Due	1,997	2,150
Current	651,062	602,747
Total Loans and Leases	653,059	604,897
Loans and Leases Past Due Greater Than 90 Days and Accruing	0	0
Nonaccrual Loans and Leases	1,842	1,979
Originated | Consumer loans | Home equity
Age analysis of past due loans
Past Due	969	694
Current	330,045	313,495
Total Loans and Leases	331,014	314,189
Loans and Leases Past Due Greater Than 90 Days and Accruing	1	1
Nonaccrual Loans and Leases	191	132
Originated | Consumer loans | Other consumer
Age analysis of past due loans
Past Due	84	286
Current	23,176	14,381
Total Loans and Leases	23,260	14,667
Loans and Leases Past Due Greater Than 90 Days and Accruing	0	0
Nonaccrual Loans and Leases	17	43
Originated | 31-60 days past due
Age analysis of past due loans
Past Due	12,391	23,524
Originated | 31-60 days past due | Commercial real estate loans
Age analysis of past due loans
Past Due	6,329	15,972
Originated | 31-60 days past due | Commercial real estate loans | Commercial real estate
Age analysis of past due loans
Past Due	5,139	3,294
Originated | 31-60 days past due | Commercial real estate loans | Multi-family mortgage
Age analysis of past due loans
Past Due	893	6,141
Originated | 31-60 days past due | Commercial real estate loans | Construction
Age analysis of past due loans
Past Due	297	6,537
Originated | 31-60 days past due | Commercial loans and leases
Age analysis of past due loans
Past Due	4,850	5,415
Originated | 31-60 days past due | Commercial loans and leases | Commercial
Age analysis of past due loans
Past Due	2,021	1,344
Originated | 31-60 days past due | Commercial loans and leases | Equipment financing
Age analysis of past due loans
Past Due	2,509	3,214
Originated | 31-60 days past due | Commercial loans and leases | Condominium association
Age analysis of past due loans
Past Due	320	857
Originated | 31-60 days past due | Consumer loans
Age analysis of past due loans
Past Due	1,212	2,137
Originated | 31-60 days past due | Consumer loans | Residential mortgage
Age analysis of past due loans
Past Due	400	1,256
Originated | 31-60 days past due | Consumer loans | Home equity
Age analysis of past due loans
Past Due	761	643
Originated | 31-60 days past due | Consumer loans | Other consumer
Age analysis of past due loans
Past Due	51	238
Originated | 61-90 days past due
Age analysis of past due loans
Past Due	2,171	6,869
Originated | 61-90 days past due | Commercial real estate loans
Age analysis of past due loans
Past Due	896	3,311
Originated | 61-90 days past due | Commercial real estate loans | Commercial real estate
Age analysis of past due loans
Past Due	896	391
Originated | 61-90 days past due | Commercial real estate loans | Multi-family mortgage
Age analysis of past due loans
Past Due	0	2,590
Originated | 61-90 days past due | Commercial real estate loans | Construction
Age analysis of past due loans
Past Due	0	330
Originated | 61-90 days past due | Commercial loans and leases
Age analysis of past due loans
Past Due	1,232	3,353
Originated | 61-90 days past due | Commercial loans and leases | Commercial
Age analysis of past due loans
Past Due	582	597
Originated | 61-90 days past due | Commercial loans and leases | Equipment financing
Age analysis of past due loans
Past Due	650	2,494
Originated | 61-90 days past due | Commercial loans and leases | Condominium association
Age analysis of past due loans
Past Due	0	262
Originated | 61-90 days past due | Consumer loans
Age analysis of past due loans
Past Due	43	205
Originated | 61-90 days past due | Consumer loans | Residential mortgage
Age analysis of past due loans
Past Due	0	166
Originated | 61-90 days past due | Consumer loans | Home equity
Age analysis of past due loans
Past Due	25	19
Originated | 61-90 days past due | Consumer loans | Other consumer
Age analysis of past due loans
Past Due	18	20
Originated | Greater than 90 days past due
Age analysis of past due loans
Past Due	17,227	14,418
Originated | Greater than 90 days past due | Commercial real estate loans
Age analysis of past due loans
Past Due	3,503	2,703
Originated | Greater than 90 days past due | Commercial real estate loans | Commercial real estate
Age analysis of past due loans
Past Due	2,962	1,843
Originated | Greater than 90 days past due | Commercial real estate loans | Multi-family mortgage
Age analysis of past due loans
Past Due	145	0
Originated | Greater than 90 days past due | Commercial real estate loans | Construction
Age analysis of past due loans
Past Due	396	860
Originated | Greater than 90 days past due | Commercial loans and leases
Age analysis of past due loans
Past Due	11,929	10,927
Originated | Greater than 90 days past due | Commercial loans and leases | Commercial
Age analysis of past due loans
Past Due	6,244	7,724
Originated | Greater than 90 days past due | Commercial loans and leases | Equipment financing
Age analysis of past due loans
Past Due	5,685	3,203
Originated | Greater than 90 days past due | Commercial loans and leases | Condominium association
Age analysis of past due loans
Past Due	0	0
Originated | Greater than 90 days past due | Consumer loans
Age analysis of past due loans
Past Due	1,795	788
Originated | Greater than 90 days past due | Consumer loans | Residential mortgage
Age analysis of past due loans
Past Due	1,597	728
Originated | Greater than 90 days past due | Consumer loans | Home equity
Age analysis of past due loans
Past Due	183	32
Originated | Greater than 90 days past due | Consumer loans | Other consumer
Age analysis of past due loans
Past Due	15	28
Acquired
Age analysis of past due loans
Past Due	13,661	5,893
Current	380,746	234,164
Total Loans and Leases	394,407	240,057
Loans and Leases Past Due Greater Than 90 Days and Accruing	11,230	2,795
Nonaccrual Loans and Leases	1,329	1,997
Acquired | Commercial real estate
Age analysis of past due loans
Total Loans and Leases	121,821	105,577
Acquired | Multi-family mortgage
Age analysis of past due loans
Total Loans and Leases	47,898	24,749
Acquired | Construction
Age analysis of past due loans
Total Loans and Leases	22,162	0
Acquired | Commercial
Age analysis of past due loans
Total Loans and Leases	23,788	8,179
Acquired | Equipment financing
Age analysis of past due loans
Total Loans and Leases	3,249	4,514
Acquired | Condominium association
Age analysis of past due loans
Total Loans and Leases	0	0
Acquired | Residential mortgage
Age analysis of past due loans
Total Loans and Leases	129,909	55,168
Acquired | Home equity
Age analysis of past due loans
Total Loans and Leases	45,470	41,765
Acquired | Other consumer
Age analysis of past due loans
Total Loans and Leases	110	105
Acquired | Commercial real estate loans
Age analysis of past due loans
Past Due	10,252	1,667
Current	181,629	128,659
Total Loans and Leases	191,881	130,326
Loans and Leases Past Due Greater Than 90 Days and Accruing	9,018	589
Nonaccrual Loans and Leases	122	131
Acquired | Commercial real estate loans | Commercial real estate
Age analysis of past due loans
Past Due	9,302	1,664
Current	112,519	103,913
Total Loans and Leases	121,821	105,577
Loans and Leases Past Due Greater Than 90 Days and Accruing	9,018	586
Nonaccrual Loans and Leases	122	131
Acquired | Commercial real estate loans | Multi-family mortgage
Age analysis of past due loans
Past Due	348	3
Current	47,550	24,746
Total Loans and Leases	47,898	24,749
Loans and Leases Past Due Greater Than 90 Days and Accruing	0	3
Nonaccrual Loans and Leases	0	0
Acquired | Commercial real estate loans | Construction
Age analysis of past due loans
Past Due	602
Current	21,560
Total Loans and Leases	22,162
Loans and Leases Past Due Greater Than 90 Days and Accruing	0
Nonaccrual Loans and Leases	0
Acquired | Commercial loans and leases
Age analysis of past due loans
Past Due	467	1,079
Current	26,570	11,614
Total Loans and Leases	27,037	12,693
Loans and Leases Past Due Greater Than 90 Days and Accruing	99	30
Nonaccrual Loans and Leases	200	1,254
Acquired | Commercial loans and leases | Commercial
Age analysis of past due loans
Past Due	458	1,066
Current	23,330	7,113
Total Loans and Leases	23,788	8,179
Loans and Leases Past Due Greater Than 90 Days and Accruing	90	17
Nonaccrual Loans and Leases	200	1,254
Acquired | Commercial loans and leases | Equipment financing
Age analysis of past due loans
Past Due	9	13
Current	3,240	4,501
Total Loans and Leases	3,249	4,514
Loans and Leases Past Due Greater Than 90 Days and Accruing	9	13
Nonaccrual Loans and Leases	0	0
Acquired | Consumer loans
Age analysis of past due loans
Past Due	2,942	3,147
Current	172,547	93,891
Total Loans and Leases	175,489	97,038
Loans and Leases Past Due Greater Than 90 Days and Accruing	2,113	2,176
Nonaccrual Loans and Leases	1,007	612
Acquired | Consumer loans | Residential mortgage
Age analysis of past due loans
Past Due	2,484	2,453
Current	127,425	52,715
Total Loans and Leases	129,909	55,168
Loans and Leases Past Due Greater Than 90 Days and Accruing	2,113	1,990
Nonaccrual Loans and Leases	290	0
Acquired | Consumer loans | Home equity
Age analysis of past due loans
Past Due	458	694
Current	45,012	41,071
Total Loans and Leases	45,470	41,765
Loans and Leases Past Due Greater Than 90 Days and Accruing	0	186
Nonaccrual Loans and Leases	717	612
Acquired | Consumer loans | Other consumer
Age analysis of past due loans
Past Due	0	0
Current	110	105
Total Loans and Leases	110	105
Loans and Leases Past Due Greater Than 90 Days and Accruing	0	0
Nonaccrual Loans and Leases	0	0
Acquired | 31-60 days past due
Age analysis of past due loans
Past Due	1,023	1,516
Acquired | 31-60 days past due | Commercial real estate loans
Age analysis of past due loans
Past Due	708	1,008
Acquired | 31-60 days past due | Commercial real estate loans | Commercial real estate
Age analysis of past due loans
Past Due	0	1,008
Acquired | 31-60 days past due | Commercial real estate loans | Multi-family mortgage
Age analysis of past due loans
Past Due	348	0
Acquired | 31-60 days past due | Commercial real estate loans | Construction
Age analysis of past due loans
Past Due	360
Acquired | 31-60 days past due | Commercial loans and leases
Age analysis of past due loans
Past Due	124	0
Acquired | 31-60 days past due | Commercial loans and leases | Commercial
Age analysis of past due loans
Past Due	124	0
Acquired | 31-60 days past due | Commercial loans and leases | Equipment financing
Age analysis of past due loans
Past Due	0	0
Acquired | 31-60 days past due | Consumer loans
Age analysis of past due loans
Past Due	191	508
Acquired | 31-60 days past due | Consumer loans | Residential mortgage
Age analysis of past due loans
Past Due	0	0
Acquired | 31-60 days past due | Consumer loans | Home equity
Age analysis of past due loans
Past Due	191	508
Acquired | 31-60 days past due | Consumer loans | Other consumer
Age analysis of past due loans
Past Due	0	0
Acquired | 61-90 days past due
Age analysis of past due loans
Past Due	1,137	507
Acquired | 61-90 days past due | Commercial real estate loans
Age analysis of past due loans
Past Due	457	0
Acquired | 61-90 days past due | Commercial real estate loans | Commercial real estate
Age analysis of past due loans
Past Due	215	0
Acquired | 61-90 days past due | Commercial real estate loans | Multi-family mortgage
Age analysis of past due loans
Past Due	0	0
Acquired | 61-90 days past due | Commercial real estate loans | Construction
Age analysis of past due loans
Past Due	242
Acquired | 61-90 days past due | Commercial loans and leases
Age analysis of past due loans
Past Due	44	44
Acquired | 61-90 days past due | Commercial loans and leases | Commercial
Age analysis of past due loans
Past Due	44	44
Acquired | 61-90 days past due | Commercial loans and leases | Equipment financing
Age analysis of past due loans
Past Due	0	0
Acquired | 61-90 days past due | Consumer loans
Age analysis of past due loans
Past Due	636	463
Acquired | 61-90 days past due | Consumer loans | Residential mortgage
Age analysis of past due loans
Past Due	371	463
Acquired | 61-90 days past due | Consumer loans | Home equity
Age analysis of past due loans
Past Due	265	0
Acquired | 61-90 days past due | Consumer loans | Other consumer
Age analysis of past due loans
Past Due	0	0
Acquired | Greater than 90 days past due
Age analysis of past due loans
Past Due	11,501	3,870
Acquired | Greater than 90 days past due | Commercial real estate loans
Age analysis of past due loans
Past Due	9,087	659
Acquired | Greater than 90 days past due | Commercial real estate loans | Commercial real estate
Age analysis of past due loans
Past Due	9,087	656
Acquired | Greater than 90 days past due | Commercial real estate loans | Multi-family mortgage
Age analysis of past due loans
Past Due	0	3
Acquired | Greater than 90 days past due | Commercial real estate loans | Construction
Age analysis of past due loans
Past Due	0
Acquired | Greater than 90 days past due | Commercial loans and leases
Age analysis of past due loans
Past Due	299	1,035
Acquired | Greater than 90 days past due | Commercial loans and leases | Commercial
Age analysis of past due loans
Past Due	290	1,022
Acquired | Greater than 90 days past due | Commercial loans and leases | Equipment financing
Age analysis of past due loans
Past Due	9	13
Acquired | Greater than 90 days past due | Consumer loans
Age analysis of past due loans
Past Due	2,115	2,176
Acquired | Greater than 90 days past due | Consumer loans | Residential mortgage
Age analysis of past due loans
Past Due	2,113	1,990
Acquired | Greater than 90 days past due | Consumer loans | Home equity
Age analysis of past due loans
Past Due	2	186
Acquired | Greater than 90 days past due | Consumer loans | Other consumer
Age analysis of past due loans
Past Due	$ 0	$ 0

Allowance for Loan and Lease _7

Allowance for Loan and Lease Losses (Recorded Investment) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Impaired Loans and Leases
Recorded investment	$ 63,765	$ 58,685
Unpaid principal balance	63,839	58,745
Related allowance	3,081	3,127
Average recorded investment	62,035	72,845	$ 71,519
Interest income recognized, Total	1,329	1,404	1,331
Recorded investment in loans and leases by portfolio segment
Total, Allowance	58,692	58,592
Total Loans and Leases	6,303,516	5,730,679
Originated
Impaired Loans and Leases
Recorded investment, loans with no related allowance recorded	39,485	38,392
Recorded investment, loans with related allowance recorded	9,285	11,968
Recorded investment	48,770	50,360
Unpaid principal balance with no related allowance recorded	39,576	38,502
Unpaid principal balance with related allowance recorded	9,268	11,918
Unpaid principal balance	48,844	50,420
Related allowance	3,055	3,105
Recorded investment, nonaccrual loans	22,700	24,900
Average recorded investment with no related allowance recorded	35,799	39,461	34,179
Average recorded investment with related allowance recorded	9,960	21,653	14,754
Average recorded investment	45,759	61,114	48,933
Interest income recognized with no related allowance recorded	1,134	1,082	828
Interest income recognized with related allowance recorded	107	163	201
Interest income recognized, Total	1,241	1,245	1,029
Recorded investment in loans and leases by portfolio segment
Individually evaluated for impairment, allowance	3,055	3,105
Collectively evaluated for impairment, allowance	53,823	54,447
Total, Allowance	56,878	57,552
Individually evaluated for impairment, Loans and Leases	41,239	45,487
Collectively evaluated for impairment, Loans and Leases	5,867,870	5,445,135
Total Loans and Leases	5,909,109	5,490,622
Acquired
Impaired Loans and Leases
Recorded investment, loans with no related allowance recorded	14,841	8,210
Recorded investment, loans with related allowance recorded	154	115
Recorded investment	14,995	8,325
Unpaid principal balance with no related allowance recorded	14,841	8,210
Unpaid principal balance with related allowance recorded	154	115
Unpaid principal balance	14,995	8,325
Related allowance	26	22
Recorded investment, nonaccrual loans	1,300	2,000
Average recorded investment with no related allowance recorded	16,141	11,580	20,698
Average recorded investment with related allowance recorded	135	151	1,888
Average recorded investment	16,276	11,731	22,586
Interest income recognized with no related allowance recorded	84	155	294
Interest income recognized with related allowance recorded	4	4	8
Interest income recognized, Total	88	159	302
Recorded investment in loans and leases by portfolio segment
Total, Allowance	1,814	1,040
Total Loans and Leases	394,407	240,057
Financial Asset Acquired and No Credit Deterioration
Recorded investment in loans and leases by portfolio segment
Individually evaluated for impairment, allowance	26	22
Collectively evaluated for impairment, allowance	135	175
Individually evaluated for impairment, Loans and Leases	2,476	3,354
Collectively evaluated for impairment, Loans and Leases	287,407	96,564
Financial Asset Acquired with Credit Deterioration
Recorded investment in loans and leases by portfolio segment
Total, Allowance	1,653	843
Total Loans and Leases	104,524	140,139
Commercial real estate loans
Recorded investment in loans and leases by portfolio segment
Total, Allowance	28,187	27,112
Total Loans and Leases	3,351,736	3,075,777
Commercial real estate loans | Originated
Impaired Loans and Leases
Recorded investment, loans with no related allowance recorded	5,569	9,978
Recorded investment, loans with related allowance recorded	396	3,056
Unpaid principal balance with no related allowance recorded	5,545	9,962
Unpaid principal balance with related allowance recorded	396	3,056
Related allowance	5	0
Average recorded investment with no related allowance recorded	6,484	10,181	6,608
Average recorded investment with related allowance recorded	99	3,271	4,715
Interest income recognized with no related allowance recorded	87	277	152
Interest income recognized with related allowance recorded	0	162	195
Recorded investment in loans and leases by portfolio segment
Individually evaluated for impairment, allowance	5	0
Collectively evaluated for impairment, allowance	26,617	26,366
Total, Allowance	26,622	26,366
Individually evaluated for impairment, Loans and Leases	5,610	13,031
Collectively evaluated for impairment, Loans and Leases	3,154,245	2,932,420
Total Loans and Leases	3,159,855	2,945,451
Commercial real estate loans | Acquired
Impaired Loans and Leases
Recorded investment, loans with no related allowance recorded	9,538	1,880
Unpaid principal balance with no related allowance recorded	9,538	1,880
Average recorded investment with no related allowance recorded	9,868	4,005	8,906
Average recorded investment with related allowance recorded	0	0	1,093
Interest income recognized with no related allowance recorded	7	55	151
Interest income recognized with related allowance recorded	0	0	0
Recorded investment in loans and leases by portfolio segment
Total, Allowance	1,565	746
Total Loans and Leases	191,881	130,326
Commercial real estate loans | Financial Asset Acquired and No Credit Deterioration
Recorded investment in loans and leases by portfolio segment
Individually evaluated for impairment, allowance	0	0
Collectively evaluated for impairment, allowance	32	145
Individually evaluated for impairment, Loans and Leases	0	0
Collectively evaluated for impairment, Loans and Leases	121,119	34,244
Commercial real estate loans | Financial Asset Acquired with Credit Deterioration
Recorded investment in loans and leases by portfolio segment
Total, Allowance	1,533	601
Total Loans and Leases	70,762	96,082
Commercial
Recorded investment in loans and leases by portfolio segment
Total, Allowance	25,283	26,333
Total Loans and Leases	1,768,958	1,624,111
Commercial | Originated
Impaired Loans and Leases
Recorded investment, loans with no related allowance recorded	30,927	24,906
Recorded investment, loans with related allowance recorded	8,224	8,912
Unpaid principal balance with no related allowance recorded	31,053	25,040
Unpaid principal balance with related allowance recorded	8,208	8,862
Related allowance	2,961	3,105
Average recorded investment with no related allowance recorded	26,514	24,950	23,445
Average recorded investment with related allowance recorded	9,026	18,382	9,915
Interest income recognized with no related allowance recorded	993	747	600
Interest income recognized with related allowance recorded	96	1	6
Recorded investment in loans and leases by portfolio segment
Individually evaluated for impairment, allowance	2,961	3,105
Collectively evaluated for impairment, allowance	22,131	23,078
Total, Allowance	25,092	26,183
Individually evaluated for impairment, Loans and Leases	32,127	29,386
Collectively evaluated for impairment, Loans and Leases	1,709,794	1,582,032
Total Loans and Leases	1,741,921	1,611,418
Commercial | Acquired
Impaired Loans and Leases
Recorded investment, loans with no related allowance recorded	531	1,594
Unpaid principal balance with no related allowance recorded	531	1,594
Average recorded investment with no related allowance recorded	1,212	2,280	4,255
Average recorded investment with related allowance recorded	0	0	364
Interest income recognized with no related allowance recorded	16	31	75
Interest income recognized with related allowance recorded	0	0	0
Recorded investment in loans and leases by portfolio segment
Total, Allowance	191	150
Total Loans and Leases	27,037	12,693
Commercial | Financial Asset Acquired and No Credit Deterioration
Recorded investment in loans and leases by portfolio segment
Individually evaluated for impairment, allowance	0	0
Collectively evaluated for impairment, allowance	83	13
Individually evaluated for impairment, Loans and Leases	404	1,487
Collectively evaluated for impairment, Loans and Leases	24,094	6,399
Commercial | Financial Asset Acquired with Credit Deterioration
Recorded investment in loans and leases by portfolio segment
Total, Allowance	108	137
Total Loans and Leases	2,539	4,807
Consumer loans
Recorded investment in loans and leases by portfolio segment
Total, Allowance	5,222	5,147
Total Loans and Leases	1,182,822	1,030,791
Consumer loans | Originated
Impaired Loans and Leases
Recorded investment, loans with no related allowance recorded	2,989	3,508
Recorded investment, loans with related allowance recorded	665	0
Unpaid principal balance with no related allowance recorded	2,978	3,500
Unpaid principal balance with related allowance recorded	664	0
Related allowance	89	0
Average recorded investment with no related allowance recorded	2,801	4,330	4,126
Average recorded investment with related allowance recorded	835	0	124
Interest income recognized with no related allowance recorded	54	58	76
Interest income recognized with related allowance recorded	11	0	0
Recorded investment in loans and leases by portfolio segment
Individually evaluated for impairment, allowance	89	0
Collectively evaluated for impairment, allowance	5,075	5,003
Total, Allowance	5,164	5,003
Individually evaluated for impairment, Loans and Leases	3,502	3,070
Collectively evaluated for impairment, Loans and Leases	1,003,831	930,683
Total Loans and Leases	1,007,333	933,753
Consumer loans | Acquired
Impaired Loans and Leases
Recorded investment, loans with no related allowance recorded	4,772	4,736
Recorded investment, loans with related allowance recorded	154	115
Unpaid principal balance with no related allowance recorded	4,772	4,736
Unpaid principal balance with related allowance recorded	154	115
Related allowance	26	22
Average recorded investment with no related allowance recorded	5,061	5,295	7,537
Average recorded investment with related allowance recorded	135	151	431
Interest income recognized with no related allowance recorded	61	69	68
Interest income recognized with related allowance recorded	4	4	$ 8
Recorded investment in loans and leases by portfolio segment
Total, Allowance	58	144
Total Loans and Leases	175,489	97,038
Consumer loans | Financial Asset Acquired and No Credit Deterioration
Recorded investment in loans and leases by portfolio segment
Individually evaluated for impairment, allowance	26	22
Collectively evaluated for impairment, allowance	20	17
Individually evaluated for impairment, Loans and Leases	2,072	1,867
Collectively evaluated for impairment, Loans and Leases	142,194	55,921
Consumer loans | Financial Asset Acquired with Credit Deterioration
Recorded investment in loans and leases by portfolio segment
Total, Allowance	12	105
Total Loans and Leases	$ 31,223	$ 39,250

Allowance for Loan and Lease _8

Allowance for Loan and Lease Losses (Troubled Debt Restructurings) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)loan	Dec. 31, 2017USD ($)loan	Dec. 31, 2016USD ($)loan
Receivables [Abstract]
On accrual	$ 12,257	$ 16,241
On nonaccrual	8,684	9,770
Total troubled debt restructurings	$ 20,900	26,000
Financing Receivable, Modifications [Line Items]
Number of Loans/ Leases | loan	30		32
Recorded Investment, At Modification	$ 5,843		$ 12,027
Recorded Investment, At end of period	5,792	7,000	8,021
Specific Allowance for Loan and Lease Losses	782		20
Nonaccrual Loans and Leases	$ 4,296		$ 7,798
Defaulted, number of loans/leases | loan	3		4
Defaulted, recorded investment	$ 1,416		$ 705
Loans with one modification	5,368	4,917	7,796
Loans with more than one modification	424	2,084	225
Extended maturity
Financing Receivable, Modifications [Line Items]
Loans with one modification	1,717	2,810	599
Loans with more than one modification	0	1,910	225
Adjusted principal
Financing Receivable, Modifications [Line Items]
Loans with one modification	0	19	249
Interest only
Financing Receivable, Modifications [Line Items]
Loans with one modification	0	174	1,493
Combination maturity, principal, interest rate
Financing Receivable, Modifications [Line Items]
Loans with one modification	3,651	1,914	5,455
Loans with more than one modification	$ 424	$ 174	$ 0
Originated
Financing Receivable, Modifications [Line Items]
Number of Loans/ Leases | loan	28	27	27
Recorded Investment, At Modification	$ 5,594	$ 10,737	$ 11,653
Recorded Investment, At end of period	5,547	7,001	7,653
Specific Allowance for Loan and Lease Losses	782	328	0
Nonaccrual Loans and Leases	$ 4,051	$ 3,629	$ 7,653
Defaulted, number of loans/leases | loan	3	3	4
Defaulted, recorded investment	$ 1,416	$ 1,549	$ 705
Originated | Commercial real estate
Financing Receivable, Modifications [Line Items]
Number of Loans/ Leases | loan	1	1
Recorded Investment, At Modification	$ 673	$ 189
Recorded Investment, At end of period	652	189
Specific Allowance for Loan and Lease Losses	0	0
Nonaccrual Loans and Leases	$ 653	$ 0
Defaulted, number of loans/leases | loan	0	0
Defaulted, recorded investment	$ 0	$ 0
Originated | Multi-family mortgage
Financing Receivable, Modifications [Line Items]
Number of Loans/ Leases | loan			2
Recorded Investment, At Modification			$ 1,155
Recorded Investment, At end of period			1,114
Specific Allowance for Loan and Lease Losses			0
Nonaccrual Loans and Leases			$ 1,114
Defaulted, number of loans/leases | loan			0
Defaulted, recorded investment			$ 0
Originated | Commercial
Financing Receivable, Modifications [Line Items]
Number of Loans/ Leases | loan	10	10	22
Recorded Investment, At Modification	$ 1,775	$ 7,861	$ 9,701
Recorded Investment, At end of period	1,706	3,911	6,015
Specific Allowance for Loan and Lease Losses	733	191	0
Nonaccrual Loans and Leases	$ 1,706	$ 2,189	$ 6,015
Defaulted, number of loans/leases | loan	2	2	2
Defaulted, recorded investment	$ 1,075	$ 1,361	$ 364
Originated | Equipment financing
Financing Receivable, Modifications [Line Items]
Number of Loans/ Leases | loan	14	16	3
Recorded Investment, At Modification	$ 2,510	$ 2,687	$ 797
Recorded Investment, At end of period	2,556	2,901	524
Specific Allowance for Loan and Lease Losses	37	137	0
Nonaccrual Loans and Leases	$ 1,351	$ 1,440	$ 524
Defaulted, number of loans/leases | loan	0	1	2
Defaulted, recorded investment	$ 0	$ 188	$ 341
Originated | Residential mortgage
Financing Receivable, Modifications [Line Items]
Number of Loans/ Leases | loan	2
Recorded Investment, At Modification	$ 550
Recorded Investment, At end of period	550
Specific Allowance for Loan and Lease Losses	12
Nonaccrual Loans and Leases	$ 341
Defaulted, number of loans/leases | loan	1
Defaulted, recorded investment	$ 341
Originated | Home equity
Financing Receivable, Modifications [Line Items]
Number of Loans/ Leases | loan	1
Recorded Investment, At Modification	$ 86
Recorded Investment, At end of period	83
Specific Allowance for Loan and Lease Losses	0
Nonaccrual Loans and Leases	$ 0
Defaulted, number of loans/leases | loan	0
Defaulted, recorded investment	$ 0
Acquired
Financing Receivable, Modifications [Line Items]
Number of Loans/ Leases | loan	2		5
Recorded Investment, At Modification	$ 249		$ 374
Recorded Investment, At end of period	245		368
Specific Allowance for Loan and Lease Losses	0		20
Nonaccrual Loans and Leases	$ 245		$ 145
Defaulted, number of loans/leases | loan	0		0
Defaulted, recorded investment	$ 0		$ 0
Acquired | Home equity
Financing Receivable, Modifications [Line Items]
Number of Loans/ Leases | loan	2		5
Recorded Investment, At Modification	$ 249		$ 374
Recorded Investment, At end of period	245		368
Specific Allowance for Loan and Lease Losses	0		20
Nonaccrual Loans and Leases	$ 245		$ 145
Defaulted, number of loans/leases | loan	0		0
Defaulted, recorded investment	$ 0		$ 0

Allowance for Loan and Lease _9

Allowance for Loan and Lease Losses (Narrative) (Details)	12 Months Ended
	Dec. 31, 2018USD ($)class	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Financing Receivable, Allowance for Credit Losses [Line Items]
Unfunded credit commitments liability included in other liabilities	$ 1,900,000	$ 1,700,000
Unfunded credit commitments liability charge-off	0	0	$ 0
Total loans and leases	6,303,516,000	5,730,679,000
Related allowance	3,081,000	3,127,000
Specific allowance for loan and lease losses	3,100,000	3,100,000
General allowance for loan and lease losses	55,600,000	55,500,000
Total troubled debt restructurings	20,900,000	26,000,000
Nonaccrual Loans and Leases	24,097,000	27,272,000
Charge-offs	7,228,000	15,811,000	14,667,000
Increase in general portion of the allowance for loan and lease losses	100,000
Increase (decrease) in financing receivable, modifications	$ (5,100,000)
Number of days past due, non-accrual status (in days)	90 days
Financial impact of modification of performing and nonperforming loans	$ 1,200,000	4,800,000	4,300,000
Commitments to lend funds to debtors owing receivables whose terms had been modified in troubled debt restructurings	0
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	2,330,725,000	2,174,969,000
Multi-family mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	847,711,000	760,670,000
Construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	173,300,000	140,138,000
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	736,418,000	705,004,000
Equipment financing
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	982,089,000	866,488,000
Condominium association
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	50,451,000	52,619,000
Residential mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	782,968,000	660,065,000
Home equity
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	376,484,000	355,954,000
Other consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	23,370,000	14,772,000
Taxi Medallion Portfolio
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	13,700,000	19,700,000
Related allowance	2,500,000	3,800,000
Specific allowance for loan and lease losses	1,900,000	2,700,000
General allowance for loan and lease losses	600,000	1,100,000
Total troubled debt restructurings	3,700,000	3,700,000
Nonaccrual Loans and Leases	3,700,000	7,800,000
Charge-offs	$ 3,800,000
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Number of loan classes within specific portfolio | class	3
Commercial loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Number of loan classes within specific portfolio | class	3
Total loans and leases	$ 1,768,958,000	1,624,111,000
Charge-offs	6,585,000	14,914,000	10,516,000
Commercial loans | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	$ 736,418,000	705,004,000
Percentage of loans to aggregate outstanding amount	11.70%
Commercial loans | Equipment financing
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	$ 982,089,000	866,488,000
Percentage of loans to aggregate outstanding amount	15.60%
Commercial loans | Condominium association
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	$ 50,451,000	52,619,000
Percentage of loans to aggregate outstanding amount	0.80%
Consumer Loan
Financing Receivable, Allowance for Credit Losses [Line Items]
Number of loan classes within specific portfolio | class	3
Commercial real estate loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Number of loan classes within specific portfolio | class	3
Total loans and leases	$ 3,351,736,000	3,075,777,000
Charge-offs	103,000	494,000	2,169,000
Commercial real estate loans | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	$ 2,330,725,000	2,174,969,000
Percentage of loans to aggregate outstanding amount	37.00%
Commercial real estate loans | Multi-family mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	$ 847,711,000	760,670,000
Percentage of loans to aggregate outstanding amount	13.40%
Commercial real estate loans | Construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	$ 173,300,000	140,138,000
Percentage of loans to aggregate outstanding amount	2.70%
Consumer loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Number of loan classes within specific portfolio | class	3
Total loans and leases	$ 1,182,822,000	1,030,791,000
Charge-offs	$ 540,000	403,000	$ 1,982,000
Loans not made, loan to value ratio, minimum (as a percent)	80.00%
Number of days past due, non-accrual status (in days)	90 days
Consumer loans | Residential mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	$ 782,968,000	660,065,000
Percentage of loans to aggregate outstanding amount	12.40%
Consumer loans | Home equity
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	$ 376,484,000	355,954,000
Percentage of loans to aggregate outstanding amount	6.00%
Consumer loans | Other consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	$ 23,370,000	14,772,000
Percentage of loans to aggregate outstanding amount	0.40%
Originated
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	$ 5,909,109,000	5,490,622,000
Related allowance	3,055,000	3,105,000
Nonaccrual Loans and Leases	22,768,000	25,275,000
Originated | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	2,208,904,000	2,069,392,000
Originated | Multi-family mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	799,813,000	735,921,000
Originated | Construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	151,138,000	140,138,000
Originated | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	712,630,000	696,825,000
Originated | Equipment financing
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	978,840,000	861,974,000
Originated | Condominium association
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	50,451,000	52,619,000
Originated | Residential mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	653,059,000	604,897,000
Originated | Home equity
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	331,014,000	314,189,000
Originated | Other consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	23,260,000	14,667,000
Originated | Commercial loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	1,741,921,000	1,611,418,000
Related allowance	2,961,000	3,105,000
Nonaccrual Loans and Leases	16,186,000	18,471,000
Originated | Commercial loans | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	712,630,000	696,825,000
Nonaccrual Loans and Leases	6,421,000	10,365,000
Originated | Commercial loans | Equipment financing
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	978,840,000	861,974,000
Nonaccrual Loans and Leases	9,500,000	8,106,000
Originated | Commercial loans | Condominium association
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	50,451,000	52,619,000
Nonaccrual Loans and Leases	265,000	0
Originated | Commercial real estate loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	3,159,855,000	2,945,451,000
Related allowance	5,000	0
Nonaccrual Loans and Leases	4,532,000	4,650,000
Originated | Commercial real estate loans | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	2,208,904,000	2,069,392,000
Nonaccrual Loans and Leases	3,806,000	3,182,000
Originated | Commercial real estate loans | Multi-family mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	799,813,000	735,921,000
Nonaccrual Loans and Leases	330,000	608,000
Originated | Commercial real estate loans | Construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	151,138,000	140,138,000
Nonaccrual Loans and Leases	396,000	860,000
Originated | Consumer loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	1,007,333,000	933,753,000
Related allowance	89,000	0
Nonaccrual Loans and Leases	2,050,000	2,154,000
Originated | Consumer loans | Residential mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	653,059,000	604,897,000
Nonaccrual Loans and Leases	1,842,000	1,979,000
Originated | Consumer loans | Home equity
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	331,014,000	314,189,000
Nonaccrual Loans and Leases	191,000	132,000
Originated | Consumer loans | Other consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	23,260,000	14,667,000
Nonaccrual Loans and Leases	17,000	43,000
Acquired
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	394,407,000	240,057,000
Related allowance	26,000	22,000
Nonaccrual Loans and Leases	1,329,000	1,997,000
Acquired | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	121,821,000	105,577,000
Acquired | Multi-family mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	47,898,000	24,749,000
Acquired | Construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	22,162,000	0
Acquired | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	23,788,000	8,179,000
Acquired | Equipment financing
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	3,249,000	4,514,000
Acquired | Condominium association
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	0	0
Acquired | Residential mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	129,909,000	55,168,000
Acquired | Home equity
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	45,470,000	41,765,000
Acquired | Other consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	110,000	105,000
Acquired | Commercial loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	27,037,000	12,693,000
Nonaccrual Loans and Leases	200,000	1,254,000
Acquired | Commercial loans | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	23,788,000	8,179,000
Nonaccrual Loans and Leases	200,000	1,254,000
Acquired | Commercial loans | Equipment financing
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	3,249,000	4,514,000
Nonaccrual Loans and Leases	0	0
Acquired | Commercial real estate loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	191,881,000	130,326,000
Nonaccrual Loans and Leases	122,000	131,000
Acquired | Commercial real estate loans | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	121,821,000	105,577,000
Nonaccrual Loans and Leases	122,000	131,000
Acquired | Commercial real estate loans | Multi-family mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	47,898,000	24,749,000
Nonaccrual Loans and Leases	0	0
Acquired | Commercial real estate loans | Construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	22,162,000
Nonaccrual Loans and Leases	0
Acquired | Consumer loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	175,489,000	97,038,000
Related allowance	26,000	22,000
Nonaccrual Loans and Leases	1,007,000	612,000
Acquired | Consumer loans | Residential mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	129,909,000	55,168,000
Nonaccrual Loans and Leases	290,000	0
Acquired | Consumer loans | Home equity
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	45,470,000	41,765,000
Nonaccrual Loans and Leases	717,000	612,000
Acquired | Consumer loans | Other consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	110,000	105,000
Nonaccrual Loans and Leases	$ 0	$ 0

Premises and Equipment (Summary

Premises and Equipment (Summary of Premises and Equipment) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Premises and Equipment
Premises and Equipment, gross amount	$ 146,522	$ 143,706
Accumulated depreciation and amortization	70,140	63,423
Total premises and equipment	76,382	80,283
Land
Premises and Equipment
Premises and Equipment, gross amount	12,300	11,057
Fine art
Premises and Equipment
Premises and Equipment, gross amount	533	495
Computer equipment
Premises and Equipment
Premises and Equipment, gross amount	$ 10,488	$ 9,728
Estimated useful life	3 years	3 years
Vehicles
Premises and Equipment
Premises and Equipment, gross amount	$ 126	$ 126
Core processing system and software
Premises and Equipment
Premises and Equipment, gross amount	20,466	19,791
Furniture, fixtures and equipment
Premises and Equipment
Premises and Equipment, gross amount	14,696	14,226
Office building and improvements
Premises and Equipment
Premises and Equipment, gross amount	$ 87,913	$ 88,283
Minimum | Vehicles
Premises and Equipment
Estimated useful life	3 years	3 years
Minimum | Core processing system and software
Premises and Equipment
Estimated useful life	3 years	3 years
Minimum | Furniture, fixtures and equipment
Premises and Equipment
Estimated useful life	5 years	5 years
Minimum | Office building and improvements
Premises and Equipment
Estimated useful life	10 years	10 years
Maximum | Vehicles
Premises and Equipment
Estimated useful life	5 years	5 years
Maximum | Core processing system and software
Premises and Equipment
Estimated useful life	7 years 6 months	7 years 6 months
Maximum | Furniture, fixtures and equipment
Premises and Equipment
Estimated useful life	25 years	25 years
Maximum | Office building and improvements
Premises and Equipment
Estimated useful life	40 years	40 years

Premises and Equipment (Narrati

Premises and Equipment (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Depreciation and amortization	$ 7.5	$ 7.4	$ 7.2

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets (Rollforward of Goodwill) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Balance at beginning of year	$ 137,890	$ 137,890	$ 137,890
Additions	22,537	0	0
Balance at end of year	$ 160,427	$ 137,890	$ 137,890

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets (Summary of Intangible Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Other intangibe assets:
Gross amount	$ 41,904	$ 39,782
Accumulated amortization	35,818	33,738
Carrying Amount	6,086	6,044
Core deposits
Other intangibe assets:
Gross amount	38,294	36,172
Accumulated amortization	33,297	31,217
Carrying Amount	4,997	4,955
Trade name
Other intangibe assets:
Gross amount	1,600	1,600
Accumulated amortization	511	511
Carrying Amount	1,089	1,089
Trust relationship
Other intangibe assets:
Gross amount	1,568	1,568
Accumulated amortization	1,568	1,568
Carrying Amount	0	0
Other intangible
Other intangibe assets:
Gross amount	442	442
Accumulated amortization	442	442
Carrying Amount	$ 0	$ 0

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2013
Indefinite-lived Intangible Assets [Line Items]
Impairment losses	$ 0	$ 0	$ 0
Trade name
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible assets				$ 1,100,000
Core deposits
Indefinite-lived Intangible Assets [Line Items]
Weighted-average amortization period	7 years 10 months 24 days

Goodwill and Other Intangible_6

Goodwill and Other Intangible Assets (Future Amortization Expense) (Details) $ in Thousands	Dec. 31, 2018USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2,019	$ 1,699
2,020	1,261
2,021	850
2,022	494
2,023	263
Thereafter	430
Total	$ 4,997

Other Assets (Narrative) (Detai

Other Assets (Narrative) (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018USD ($)project	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2018USD ($)policyproject	Dec. 31, 2017USD ($)policy	Dec. 31, 2016USD ($)policy	Dec. 31, 2014USD ($)	Jan. 01, 2015USD ($)
Business Acquisition [Line Items]
Number of policies owned | policy									9	9	9
Net income attributable to Brookline Bancorp, Inc.	$ 21,138	$ 22,460	$ 20,831	$ 18,633	$ 6,827	$ 15,366	$ 14,880	$ 13,445	$ 83,062	$ 50,518	$ 52,362
Accounting Standards Update 2014-01
Business Acquisition [Line Items]
Net income attributable to Brookline Bancorp, Inc.												$ 500
Retained earnings													$ 1,100
Affordable housing project
Business Acquisition [Line Items]
Number of investments | project	13								13
Maximum percentage of outstanding equity interest that can be invested by the entity in any single project									50.00%
Other non-interest income
Business Acquisition [Line Items]
Tax exempt BOLI income									$ 1,000	$ 1,000	$ 1,100
BankRI
Business Acquisition [Line Items]
Number of policies owned | policy									7	7
Net cash surrender value	$ 39,900				38,900				$ 39,900	$ 38,900
First Ipswich
Business Acquisition [Line Items]
Number of policies owned | policy									2	2
Net cash surrender value	$ 800				$ 800				$ 800	$ 800

Other Assets (Additional Inform

Other Assets (Additional Information on Investments in Affordable Housing Projects) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Investments in Affordable Housing Projects [Abstract]
Investments in affordable housing projects included in other assets	[1]	$ 103,214	$ 91,609
Unfunded commitments related to affordable housing projects included in other liabilities		1,900	1,700
Investment amortization included in provision for income taxes		1,916	1,844	$ 1,726
Amount recognized as income tax benefit		585	623	$ 598
Affordable housing project
Investments in Affordable Housing Projects [Abstract]
Investments in affordable housing projects included in other assets		10,895	11,432
Unfunded commitments related to affordable housing projects included in other liabilities		1,115	1,933
Investment in affordable housing tax credits		1,885	1,745
Investment in affordable housing tax benefits		$ 585	$ 653
[1]	Previously reported amounts prior to January 1, 2015 have been restated to reflect a retrospective change in accounting principle for investments in qualified affordable housing projects, in accordance with ASU 2014-01. Refer to Note 10, "Other Assets".

Deposits (Summary of Deposits)

Deposits (Summary of Deposits) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Banking and Thrift [Abstract]
Demand checking accounts	$ 1,033,551	$ 942,583
NOW accounts	336,317	350,568
Savings accounts	619,961	646,359
Money market accounts	1,675,050	1,724,363
Total core deposit accounts	3,664,879	3,663,873
Certificate of deposit accounts maturing:
Within six months	475,303	363,866
After six months but within 1 year	562,018	342,500
After 1 year but within 2 years	538,435	300,921
After 2 years but within 3 years	95,806	90,805
After 3 years but within 4 years	46,027	57,926
After 4 years but within 5 years	71,556	50,380
After 5 Years	20	1,072
Total certificate of deposit accounts	1,789,165	1,207,470
Total deposits	$ 5,454,044	$ 4,871,343
Weighted Average Rate of Demand checking accounts
Demand checking accounts (as a percent)	0.00%	0.00%
NOW accounts (as a percent)	0.10%	0.07%
Savings accounts (as a percent)	0.32%	0.25%
Money market savings accounts (as a percent)	1.18%	0.56%
Total transaction deposit accounts (as a percent)	0.60%	0.31%
Weighted Average Rate of Certificate of deposit accounts maturing:
Within six months (as a percent)	1.20%	0.93%
After six months but within 1 year (as a percent)	1.40%	1.09%
After 1 year but within 2 years (as a percent)	1.85%	1.48%
After 2 years but within 3 years (as a percent)	2.16%	1.87%
After 3 years but within 4 years (as a percent)	1.73%	1.79%
After 4 years but within 5 years (as a percent)	2.57%	2.02%
After 5 years (as a percent)	1.98%	1.03%
Total certificate of deposit accounts (as a percent)	1.58%	1.27%
Total of weighted average rate of deposits (as a percent)	0.92%	0.55%

Deposits (Interest Expense) (De

Deposits (Interest Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest-bearing deposits:
NOW accounts	$ 283	$ 225	$ 209
Savings accounts	1,804	1,297	1,322
Money market accounts	15,369	8,863	7,549
Certificate of deposit accounts	24,522	12,903	10,990
Total interest-bearing deposits	$ 41,978	$ 23,288	$ 20,070

Deposits (Narrative) (Details)

Deposits (Narrative) (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Banking and Thrift [Abstract]
Threshold for disclosure of time deposit issued amounts	$ 250,000	$ 250,000
Time Deposits, $100,000 or More	480,800,000	265,800,000
Related party deposits	59,800,000	41,400,000
Deposits pledged as collateral	$ 211,500,000	$ 165,500,000

Borrowed Funds (Components and

Borrowed Funds (Components and Interest Expenses of Borrowed Funds) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Total borrowed funds	$ 920,542	$ 1,020,819
Total interest expense on borrowed funds	24,216	16,581	$ 15,914
Advances from the FHLBB
Debt Instrument [Line Items]
Total borrowed funds	784,375	889,909
Total interest expense on borrowed funds	18,650	11,330	10,760
Subordinated debentures and notes
Debt Instrument [Line Items]
Total borrowed funds	83,433	83,271
Total interest expense on borrowed funds	5,181	5,081	5,038
Other borrowed funds
Debt Instrument [Line Items]
Total borrowed funds	52,734	47,639
Total interest expense on borrowed funds	$ 385	$ 170	$ 116

Borrowed Funds (Narrative) (Det

Borrowed Funds (Narrative) (Details) - USD ($)	Sep. 15, 2014	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Securities available-for-sale and loans pledged as collateral		$ 2,400,000,000	$ 1,900,000,000
Total available borrowing capacity from Federal Home Loan Bank		2,200,000,000
Qualifying collateral available for Federal Home Loan Bank borrowings		3,200,000,000
Outstanding at end of year		920,542,000	1,020,819,000
Accretion adjustment		(2,200,000)	(2,042,000)	$ (2,158,000)
Repurchase agreements
Debt Instrument [Line Items]
Increase in agreement amount		15,100,000
Outstanding at end of year		52,700,000	37,600,000
Committed line of credit | Line of credit
Debt Instrument [Line Items]
Borrowing capacity		12,000,000
Uncommitted lines of credit | Line of credit
Debt Instrument [Line Items]
Borrowing capacity		370,000,000
Outstanding balance		0	10,000,000
Subordinated debenture maturing September 15, 2029
Debt Instrument [Line Items]
Outstanding at end of year		$ 73,926,000	73,825,000
Subordinated debenture maturing September 15, 2029 | Interest rate period 1
Debt Instrument [Line Items]
Fixed interest rate		6.00%
Subordinated debenture maturing September 15, 2029 | Interest rate period 2 | LIBOR
Debt Instrument [Line Items]
Variable interest rate spread (as a percent)		3.315%
Subordinated debenture maturing September 15, 2029 | Subordinated debentures and notes
Debt Instrument [Line Items]
Principal amount	$ 75,000,000
Accretion adjustment		$ 500,000	600,000
Capitalized financing costs		$ 1,100,000	$ 1,200,000
Subordinated debenture maturing September 15, 2029 | Subordinated debentures and notes | Interest rate period 1
Debt Instrument [Line Items]
Fixed interest rate	6.00%
Subordinated debenture maturing September 15, 2029 | Subordinated debentures and notes | Interest rate period 2 | LIBOR
Debt Instrument [Line Items]
Variable interest rate spread (as a percent)	3.315%

Borrowed Funds (FHLBB Advances)

Borrowed Funds (FHLBB Advances) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Amount
Within 1 year	$ 603,590	$ 514,314
Over 1 year to 2 years	160,073	279,928
Over 2 years to 3 years	580	16,026
Over 3 years to 4 years	3,214	30,849
Over 4 years to 5 years	0	33,217
Over 5 years	16,918	15,575
Total	784,375	889,909
Callable Amount
Within 1 year	0	55,000
Over 1 year to 2 years	0	115,000
Over 2 years to 3 years	0	0
Over 3 years to 4 years	0	0
Over 4 years to 5 years	0	0
Over 5 years	0	0
Total	$ 0	$ 170,000
Weighted Average Rate
Within 1 year (as a percent)	2.19%	1.43%
Over 1 year to 2 years (as a percent)	2.64%	1.70%
Over 2 years to 3 years (as a percent)	3.07%	0.47%
Over 3 years to 4 years (as a percent)	0.03%	0.41%
Over 4 years to 5 years (as a percent)	0.00%	0.30%
Over 5 years (as a percent)	3.45%	3.95%
Weighted average interest rate of total advances from the FHLB (as a percent)	2.30%	1.47%

Borrowed Funds (Other Borrowed

Borrowed Funds (Other Borrowed Funds) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Outstanding at end of year	$ 920,542	$ 1,020,819
Other borrowed funds
Debt Instrument [Line Items]
Outstanding at end of year	52,734	47,639
Average outstanding for the year	46,079	45,908
Maximum outstanding at any month-end	$ 55,144	$ 54,064
Weighted average rate at end of year	0.16%	0.46%
Weighted average rate paid for the year	0.83%	0.37%

Borrowed Funds (Summary of Subo

Borrowed Funds (Summary of Subordinated Debentures) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total borrowed funds	$ 920,542	$ 1,020,819
Subordinated debenture maturing June 26, 2033
Debt Instrument [Line Items]
Total borrowed funds	4,803	4,778
Subordinated debenture maturing March 17, 2034
Debt Instrument [Line Items]
Total borrowed funds	4,704	4,668
Subordinated debenture maturing September 15, 2029
Debt Instrument [Line Items]
Total borrowed funds	73,926	73,825
Subordinated Debentures Maturing June 26, 2033, March 17, 2034 and September 15, 2029
Debt Instrument [Line Items]
Total borrowed funds	$ 83,433	$ 83,271
LIBOR | Subordinated debenture maturing June 26, 2033
Debt Instrument [Line Items]
Variable interest rate spread (as a percent)	3.10%
LIBOR | Subordinated debenture maturing March 17, 2034
Debt Instrument [Line Items]
Variable interest rate spread (as a percent)	2.79%

Commitments and Contingencies_2

Commitments and Contingencies (Financial Instruments with Off-Balance Sheet Risk) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Loan commitments
Unadvanced portion of loans and leases	$ 707,997	$ 571,668
Unused lines of credit:
Home equity	487,476	407,552
Other consumer	50,404	34,191
Other commercial	347	323
Unused letters of credit:
Financial standby letters of credit	11,491	12,422
Performance standby letters of credit	3,075	736
Commercial and similar letters of credit	4,573	184
Commercial real estate
Loan commitments
Commitments to originate loans and leases	76,642	76,653
Commercial
Loan commitments
Commitments to originate loans and leases	75,713	83,270
Residential mortgage
Loan commitments
Commitments to originate loans and leases	16,363	28,745
Receive fixed, pay variable
Unused letters of credit:
Derivatives	714,500	494,659
Pay fixed, receive variable
Unused letters of credit:
Derivatives	714,500	494,659
Risk participation-out agreements
Unused letters of credit:
Derivatives	100,531	36,627
Risk participation-in agreements
Unused letters of credit:
Derivatives	35,838	3,825
Derivatives not designed as hedging instruments | Receive fixed, pay variable
Unused letters of credit:
Derivatives	714,500	494,659
Derivatives not designed as hedging instruments | Pay fixed, receive variable
Unused letters of credit:
Derivatives	714,500	494,659
Derivatives not designed as hedging instruments | Risk participation-out agreements
Unused letters of credit:
Derivatives	100,531	36,627
Derivatives not designed as hedging instruments | Risk participation-in agreements
Unused letters of credit:
Derivatives	35,838	3,825
Derivatives not designed as hedging instruments | Foreign exchange contracts | Buys foreign currency, sells U.S. currency
Unused letters of credit:
Derivatives	6,573	1,495
Derivatives not designed as hedging instruments | Foreign exchange contracts | Sells foreign currency, buys U.S. currency
Unused letters of credit:
Derivatives	$ 6,582	$ 1,502

Commitments and Contingencies_3

Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Leased Assets [Line Items]
Unfunded credit commitments liability	$ 1,900	$ 1,700
Fair value of interest rate swap assets	22,500	9,000
Fair value of interest rate swap liabilities	22,200	8,900
Derivative asset	22,488	9,002
Derivative liability	22,220	8,940
Total rental expense	5,800	5,500	$ 5,300
Rental income	$ 400	400	$ 400
Minimum
Operating Leased Assets [Line Items]
Term of operating lease	5 years
Maximum
Operating Leased Assets [Line Items]
Term of operating lease	25 years
Foreign exchange contracts
Operating Leased Assets [Line Items]
Derivative asset	$ 131	72
Derivative liability	$ 123	$ 65

Commitments and Contingencies_4

Commitments and Contingencies (Future Minimum Rental Payments) (Details) $ in Thousands	Dec. 31, 2018USD ($)
Summary of future minimum rental payments under noncancellable operating leases year ending December 31
2,019	$ 4,224
2,020	4,932
2,021	4,418
2,022	3,602
2,023	2,734
Thereafter	8,503
Total	$ 28,400

Earnings per Share (EPS) (Detai

Earnings per Share (EPS) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net income (in usd)									$ 83,062	$ 50,518	$ 52,362
Weighted average shares outstanding	80,258,489	80,315,050	80,184,977	77,879,593	76,583,712	76,452,539	74,325,013	70,386,766	79,669,668	74,459,508	70,261,954
Effect of dilutive securities									239,583	351,900	182,129
Adjusted weighted average shares outstanding	80,407,558	80,515,467	80,505,614	78,167,800	76,868,307	76,961,948	74,810,088	70,844,096	79,909,251	74,811,408	70,444,083
Basic EPS (in dollars per share)	$ 0.26	$ 0.28	$ 0.26	$ 0.24	$ 0.09	$ 0.20	$ 0.20	$ 0.19	$ 1.04	$ 0.68	$ 0.74
Diluted EPS (in dollars per share)	$ 0.26	$ 0.28	$ 0.26	$ 0.24	$ 0.09	$ 0.20	$ 0.20	$ 0.19	$ 1.04	$ 0.68	$ 0.74

Comprehensive Income_(Loss) (Ch

Comprehensive Income/(Loss) (Changes in AOCI) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Changes in accumulated other comprehensive (loss) income by component, net of tax
Balance beginning of period	$ 812,583	[1]	$ 702,749		$ 673,486
Other comprehensive loss	(3,510)		(1,069)		(1,342)
Reclassification due to the adoption of ASU No. 2018-02			1,100
Balance end of period	910,619	[1]	812,583	[1]	702,749
Accumulated Other Comprehensive Loss
Changes in accumulated other comprehensive (loss) income by component, net of tax
Balance beginning of period	(5,950)		(3,818)		(2,476)
Other comprehensive loss	(3,510)		(1,069)		(1,342)
Reclassification due to the adoption of ASU No. 2018-02			(1,063)
Balance end of period	(9,460)		(5,950)		(3,818)
Investment Securities Available-for-Sale
Changes in accumulated other comprehensive (loss) income by component, net of tax
Balance beginning of period	(6,113)		(4,213)		(2,827)
Other comprehensive loss	(3,599)		(817)		(1,386)
Reclassification due to the adoption of ASU No. 2018-02			(1,083)
Balance end of period	(9,712)		(6,113)		(4,213)
Postretirement Benefits
Changes in accumulated other comprehensive (loss) income by component, net of tax
Balance beginning of period	163		395		351
Other comprehensive loss	89		(252)		44
Reclassification due to the adoption of ASU No. 2018-02			20
Balance end of period	$ 252		$ 163		$ 395
[1]	Previously reported amounts prior to January 1, 2015 have been restated to reflect a retrospective change in accounting principle for investments in qualified affordable housing projects, in accordance with ASU 2014-01. Refer to Note 10, "Other Assets".

Derivatives and Hedging Activ_3

Derivatives and Hedging Activities (Summary of Derivative Positions) (Details)	12 Months Ended
	Dec. 31, 2018USD ($)derivative	Dec. 31, 2017USD ($)derivative
Loss Recognized in Income on Derivatives
Gain (loss) recognized in income	$ 206,000	$ 62,000
Estimated net credit risk exposure	0	0
Collateral posted	5,900,000	26,700,000
Receive fixed, pay variable
Derivatives and Hedging Activities
Total	$ 714,500,000	$ 494,659,000
Receive fixed, pay variable | Derivatives not designed as hedging instruments
Derivatives and Hedging Activities
Number of Positions | derivative	86,000	66,000
Notional Amount Maturing, Less than 1 year	$ 1,931,000	$ 3,903,000
Notional Amount Maturing, Less than 2 years	26,419,000	2,036,000
Notional Amount Maturing, Less than 3 years	0	27,992,000
Notional Amount Maturing, Less than 4 years	31,762,000	0
Notional Amount Maturing, Thereafter	654,388,000	460,728,000
Total	714,500,000	494,659,000
Fair Value	6,081,000	8,865,000
Pay fixed, receive variable
Derivatives and Hedging Activities
Total	$ 714,500,000	$ 494,659,000
Pay fixed, receive variable | Derivatives not designed as hedging instruments
Derivatives and Hedging Activities
Number of Positions | derivative	86,000	66,000
Notional Amount Maturing, Less than 1 year	$ 1,931,000	$ 3,903,000
Notional Amount Maturing, Less than 2 years	26,419,000	2,036,000
Notional Amount Maturing, Less than 3 years	0	27,992,000
Notional Amount Maturing, Less than 4 years	31,762,000	0
Notional Amount Maturing, Thereafter	654,388,000	460,728,000
Total	714,500,000	494,659,000
Fair Value	6,081,000	8,865,000
Risk participation-out agreements
Derivatives and Hedging Activities
Total	100,531,000	36,627,000
Loss Recognized in Income on Derivatives
Gain (loss) recognized in income	$ 205,000	$ 55,000
Risk participation-out agreements | Derivatives not designed as hedging instruments
Derivatives and Hedging Activities
Number of Positions | derivative	26,000	8,000
Notional Amount Maturing, Less than 1 year	$ 0	$ 0
Notional Amount Maturing, Less than 2 years	14,892,000	0
Notional Amount Maturing, Less than 3 years	0	8,613,000
Notional Amount Maturing, Less than 4 years	0	0
Notional Amount Maturing, Thereafter	85,639,000	28,014,000
Total	100,531,000	36,627,000
Fair Value	344,000	65,000
Risk participation-in agreements
Derivatives and Hedging Activities
Total	$ 35,838,000	$ 3,825,000
Risk participation-in agreements | Derivatives not designed as hedging instruments
Derivatives and Hedging Activities
Number of Positions | derivative	5,000	1,000
Notional Amount Maturing, Less than 1 year	$ 0	$ 0
Notional Amount Maturing, Less than 2 years	0	0
Notional Amount Maturing, Less than 3 years	0	0
Notional Amount Maturing, Less than 4 years	0	0
Notional Amount Maturing, Thereafter	35,838,000	3,825,000
Total	35,838,000	3,825,000
Fair Value	84,000	10,000
Foreign exchange contracts
Loss Recognized in Income on Derivatives
Gain (loss) recognized in income	$ 1,000	$ 7,000
Buys foreign currency, sells U.S. currency | Foreign exchange contracts | Derivatives not designed as hedging instruments
Derivatives and Hedging Activities
Number of Positions | derivative	22,000	22,000
Notional Amount Maturing, Less than 1 year	$ 6,573,000	$ 1,495,000
Notional Amount Maturing, Less than 2 years	0	0
Notional Amount Maturing, Less than 3 years	0	0
Notional Amount Maturing, Less than 4 years	0	0
Notional Amount Maturing, Thereafter	0	0
Total	6,573,000	1,495,000
Fair Value	$ 123,000	$ 65,000
Sells foreign currency, buys U.S. currency | Foreign exchange contracts | Derivatives not designed as hedging instruments
Derivatives and Hedging Activities
Number of Positions | derivative	37,000	44,000
Notional Amount Maturing, Less than 1 year	$ 6,582,000	$ 1,502,000
Notional Amount Maturing, Less than 2 years	0	0
Notional Amount Maturing, Less than 3 years	0	0
Notional Amount Maturing, Less than 4 years	0	0
Notional Amount Maturing, Thereafter	0	0
Total	6,582,000	1,502,000
Fair Value	$ 131,000	$ 72,000

Derivatives and Hedging Activ_4

Derivatives and Hedging Activities (Amounts Subject to Master Netting Agreement) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Asset derivatives
Assets, Gross Amounts Recognized	$ 22,488	$ 9,002
Assets, Gross Amounts Offset in the Statement of Financial Position	0	0
Assets, Net Amounts Presented in the Statement of Financial Position	22,488	9,002
Assets, Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments Pledged	0	0
Assets, Gross Amounts Not Offset in the Statement of Financial Position, Cash Collateral Pledged	50	0
Assets, Net Amount	22,438	9,002
Liability derivatives
Liabilities, Gross Amounts Recognized	22,220	8,940
Liabilities, Gross Amounts Offset in the Statement of Financial Position	0	0
Liabilities, Net Amounts Presented in the Statement of Financial Position	22,220	8,940
Liabilities, Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments Pledged	5,877	25,159
Liabilities, Gross Amounts Not Offset in the Statement of Financial Position, Cash Collateral Pledged	0	1,510
Liabilities, Net Amount	16,343	75
Loan level derivatives
Asset derivatives
Assets, Gross Amounts Recognized	22,013	8,865
Assets, Gross Amounts Offset in the Statement of Financial Position	0	0
Assets, Net Amounts Presented in the Statement of Financial Position	22,013	8,865
Assets, Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments Pledged	0	0
Assets, Gross Amounts Not Offset in the Statement of Financial Position, Cash Collateral Pledged	50	0
Assets, Net Amount	21,963	8,865
Liability derivatives
Liabilities, Gross Amounts Recognized	22,013	8,865
Liabilities, Gross Amounts Offset in the Statement of Financial Position	0	0
Liabilities, Net Amounts Presented in the Statement of Financial Position	22,013	8,865
Liabilities, Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments Pledged	5,877	25,159
Liabilities, Gross Amounts Not Offset in the Statement of Financial Position, Cash Collateral Pledged	0	1,510
Liabilities, Net Amount	16,136	0
Risk participation-out agreements
Asset derivatives
Assets, Gross Amounts Recognized	344	65
Assets, Gross Amounts Offset in the Statement of Financial Position	0	0
Assets, Net Amounts Presented in the Statement of Financial Position	344	65
Assets, Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments Pledged	0	0
Assets, Gross Amounts Not Offset in the Statement of Financial Position, Cash Collateral Pledged	0	0
Assets, Net Amount	344	65
Risk participation-in agreements
Liability derivatives
Liabilities, Gross Amounts Recognized	84	10
Liabilities, Gross Amounts Offset in the Statement of Financial Position	0	0
Liabilities, Net Amounts Presented in the Statement of Financial Position	84	10
Liabilities, Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments Pledged	0	0
Liabilities, Gross Amounts Not Offset in the Statement of Financial Position, Cash Collateral Pledged	0	0
Liabilities, Net Amount	84	10
Foreign exchange contracts
Asset derivatives
Assets, Gross Amounts Recognized	131	72
Assets, Gross Amounts Offset in the Statement of Financial Position	0	0
Assets, Net Amounts Presented in the Statement of Financial Position	131	72
Assets, Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments Pledged	0	0
Assets, Gross Amounts Not Offset in the Statement of Financial Position, Cash Collateral Pledged	0	0
Assets, Net Amount	131	72
Liability derivatives
Liabilities, Gross Amounts Recognized	123	65
Liabilities, Gross Amounts Offset in the Statement of Financial Position	0	0
Liabilities, Net Amounts Presented in the Statement of Financial Position	123	65
Liabilities, Gross Amounts Not Offset in the Statement of Financial Position, Financial Instruments Pledged	0	0
Liabilities, Gross Amounts Not Offset in the Statement of Financial Position, Cash Collateral Pledged	0	0
Liabilities, Net Amount	$ 123	$ 65

Income Taxes (Components of Inc

Income Taxes (Components of Income Tax Expense) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current provision:
Federal									$ 23,949	$ 27,825	$ 22,954
State									7,693	5,013	5,116
Total current provision									31,642	32,838	28,070
Deferred benefit (provision):
Federal									(4,323)	10,209	2,271
State									(1,130)	589	51
Total deferred benefit (provision)									(5,453)	10,798	2,322
Total provision for income taxes	$ 7,055	$ 6,140	$ 7,342	$ 5,652	$ 18,712	$ 8,330	$ 8,759	$ 7,835	$ 26,189	$ 43,636	$ 30,392

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Valuation Allowance [Line Items]
Statutory U.S federal income tax rate (as a percent)	21.00%	35.00%	35.00%
Effective income tax rate (as a percent)	23.20%	44.90%	35.50%
Decrease in expected income tax expense at statutory federal tax rate	$ 10,400
Tax Reform Act Adjustment	(707)	$ 8,965	$ 0
Merger and acquisition expense	32	138	$ 0
Net operating loss carryforwards for U.S. federal income tax purposes	4,600
Reserve for loan losses	$ 1,800
Percentage of the amount the used reserve for loan losses would be subject to taxation, if, the reserve is used for purposes other than to absorb the losses for which it was established	150.00%
Amount of liability that would result if 100% of the reserve were recaptured on which no provision has been made	$ 500
Reserve for loan losses recaptured (as a percent)	100.00%
Net deferred tax asset	$ 21,495	$ 15,061
Deferred Tax Assets
Valuation Allowance [Line Items]
Tax Reform Act Adjustment	8,600
Affordable housing project
Valuation Allowance [Line Items]
Tax Reform Act Adjustment	300
First Commons Bank
Valuation Allowance [Line Items]
Net operating loss carryforwards for U.S. federal income tax purposes	$ 3,500

Income Taxes (Reconciliation of

Income Taxes (Reconciliation of Effective Income Tax Expense) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Statutory U.S federal income tax rate (as a percent)									21.00%	35.00%	35.00%
Reconciliation of income tax expense
Expected income tax expense at statutory federal tax rate									$ 23,675	$ 34,039	$ 29,965
State taxes, net of federal income tax benefit									5,184	3,641	3,358
Bank-owned life insurance									(218)	(364)	(368)
Tax-exempt interest income									(487)	(873)	(826)
Income attributable to noncontrolling interest in subsidiary									(933)	(870)	(1,163)
Merger and acquisition expense									32	138	0
Tax Reform Act Adjustment									(707)	8,965	0
Investments in affordable housing projects									(358)	(653)	(640)
Other, net									1	(387)	66
Total provision for income taxes	$ 7,055	$ 6,140	$ 7,342	$ 5,652	$ 18,712	$ 8,330	$ 8,759	$ 7,835	$ 26,189	$ 43,636	$ 30,392
Effective income tax rate (as a percent)									23.20%	44.90%	35.50%

Income Taxes (Components of Def

Income Taxes (Components of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Allowance for loan and lease losses	$ 15,936	$ 15,618
Deferred compensation	4,692	1,032
Supplemental Executive Retirement Plans	2,846	2,805
Unrealized loss on investment securities available-for-sale	2,737	1,728
Net operating loss carryforwards	976	415
Postretirement benefits	391	400
Nonaccrual interest	482	551
Accrued expense	372	563
Restricted stock and stock option plans	497	621
Employee stock ownership plan	106	124
Other	331	67
Total gross deferred tax assets	29,366	23,924
Deferred tax liabilities:
Identified intangible assets and goodwill	2,428	2,778
Deferred loan origination costs, net	3,537	2,918
Depreciation	789	1,866
Prepaid expense	116	109
Acquisition fair value adjustments	1,001	1,192
Total gross deferred tax liabilities	7,871	8,863
Net deferred tax asset	$ 21,495	$ 15,061

Stockholders' Equity (Narrative

Stockholders' Equity (Narrative) (Details)	Mar. 01, 2018USD ($)shares	May 02, 2017USD ($)$ / sharesshares	Apr. 27, 2017$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)shares	Jan. 30, 2019USD ($)	Dec. 05, 2018USD ($)	Feb. 04, 2016USD ($)
Equity [Abstract]
Authorized serial preferred stock (in shares) | shares				50,000,000
Serial preferred stock, par value (in dollars per share) | $ / shares				$ 0.01
Preferred stock issued (in shares) | shares				0
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased (in shares) | shares				725,583	0	0
Stock repurchase program, authorized amount | $								$ 10,000,000	$ 10,000,000
Subsidiary, Sale of Stock [Line Items]
Common stock, par value (in dollars per share) | $ / shares				$ 0.01	$ 0.01
Proceeds from the issuance of common stock | $		$ 82,000,000
Liquidation account, total | $				$ 13,000,000	$ 15,100,000	$ 15,200,000
Public stock offering
Subsidiary, Sale of Stock [Line Items]
Shares in offering (in shares) | shares			5,175,000
Common stock, par value (in dollars per share) | $ / shares			$ 0.01
Sale of stock price (in usd per share) | $ / shares			$ 14.50
Underwriters option
Subsidiary, Sale of Stock [Line Items]
Shares in offering (in shares) | shares		5,951,250	776,250
Sale of stock price (in usd per share) | $ / shares		$ 14.50
Subsequent Event
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount | $							$ 10,000,000
First Commons Bank
Subsidiary, Sale of Stock [Line Items]
Total transaction value | $	$ 56,000,000
Share exchange ratio	1.089
Equity interest issued value assigned | $	$ 851,000
Equity interest issued value assigned, number of shares (in shares) | shares	3,481,477

Regulatory Capital Requiremen_3

Regulatory Capital Requirements (Narrative) (Details) - Brookline Bank	Dec. 31, 2018	Dec. 31, 2017
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total (as a percent)	10.00%	10.00%
Tier 1 (as a percent)	8.00%	8.00%
Common equity Tier 1 capital ratio, Minimum Required to Be Considered Well-Capitalized, Ratio (as a percent)	6.50%	6.50%
Tier 1 leverage capital ratio (as a percent)	5.00%	5.00%

Regulatory Capital Requiremen_4

Regulatory Capital Requirements (Summary of Regulatory Capital Requirements) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Bank actual capital amount
Common equity Tier 1 capital ratio, Actual, Amount	$ 745,103	$ 669,238
Tier 1 leverage capital	765,089	687,299
Risk-based capital:
Tier 1	765,089	687,299
Total risk-based capital	$ 899,563	$ 821,373
Bank actual capital ratio
Common equity Tier 1 capital ratio, Actual, Ratio (as a percent)	11.94%	12.02%
Tier 1 leverage capital ratio (as a percent)	10.58%	10.43%
Risk-based capital:
Tier 1 (as a percent)	12.26%	12.34%
Total (as a percent)	14.42%	14.75%
Minimum capital adequacy amount
Common equity Tier 1 capital ratio, Minimum Required for Capital Adequacy Purposes, Amount	$ 280,818	$ 250,547
Tier 1 leverage capital	289,259	263,585
Risk-based capital:
Tier 1	374,432	334,181
Total	$ 499,064	$ 445,490
Minimum capital adequacy ratio
Common equity Tier 1 capital ratio, Minimum Required for Capital Adequacy Purposes, Ratio (as a percent)	4.50%	4.50%
Tier 1 leverage capital ratio (as a percent)	4.00%	4.00%
Risk-based capital:
Tier 1 (as a percent)	6.00%	6.00%
Total (as a percent)	8.00%	8.00%
Minimum Required for Fully Phased in Capital Adequacy Purposes plus Capital Conservation Buffer
Common equity Tier 1 capital ratio	$ 436,828	$ 389,739
Tier 1 leverage capital ratio	289,259	263,585
Risk-based capital:
Tier 1 risk-based capital ratio	530,445	473,423
Total risk-based capital ratio	$ 655,022	$ 584,706
Minimum Required for Fully Phased in Capital Adequacy Purposes plus Capital Conservation Buffer
Common equity Tier 1 capital ratio (as a percent)	7.00%	7.00%
Tier 1 leverage capital ratio (as a percent)	4.00%	4.00%
Risk-based capital:
Tier 1 (as a percent)	8.50%	8.50%
Total (as a percent)	10.50%	10.50%
Brookline Bank
Bank actual capital amount
Common equity Tier 1 capital ratio, Actual, Amount	$ 495,798	$ 414,282
Tier 1 leverage capital	506,277	423,035
Risk-based capital:
Tier 1	506,277	423,035
Total risk-based capital	$ 545,533	$ 463,986
Bank actual capital ratio
Common equity Tier 1 capital ratio, Actual, Ratio (as a percent)	12.06%	11.56%
Tier 1 leverage capital ratio (as a percent)	11.02%	10.35%
Risk-based capital:
Tier 1 (as a percent)	12.32%	11.81%
Total (as a percent)	13.27%	12.95%
Minimum capital adequacy amount
Common equity Tier 1 capital ratio, Minimum Required for Capital Adequacy Purposes, Amount	$ 184,999	$ 161,269
Tier 1 leverage capital	183,767	163,492
Risk-based capital:
Tier 1	246,563	214,920
Total	$ 328,882	$ 286,632
Minimum capital adequacy ratio
Common equity Tier 1 capital ratio, Minimum Required for Capital Adequacy Purposes, Ratio (as a percent)	4.50%	4.50%
Tier 1 leverage capital ratio (as a percent)	4.00%	4.00%
Risk-based capital:
Tier 1 (as a percent)	6.00%	6.00%
Total (as a percent)	8.00%	8.00%
Minimum Required for Fully Phased in Capital Adequacy Purposes plus Capital Conservation Buffer
Common equity Tier 1 capital ratio	$ 287,777	$ 250,863
Tier 1 leverage capital ratio	183,767	163,492
Risk-based capital:
Tier 1 risk-based capital ratio	349,298	304,471
Total risk-based capital ratio	$ 431,658	$ 376,205
Minimum Required for Fully Phased in Capital Adequacy Purposes plus Capital Conservation Buffer
Common equity Tier 1 capital ratio (as a percent)	7.00%	7.00%
Tier 1 leverage capital ratio (as a percent)	4.00%	4.00%
Risk-based capital:
Tier 1 (as a percent)	8.50%	8.50%
Total (as a percent)	10.50%	10.50%
Classified as well capitalized
Common equity Tier 1 capital ratio, Minimum Required to Be Considered Well-Capitalized, Amount	$ 267,221	$ 232,944
Tier 1 leverage capital	229,708	204,365
Risk-based capital:
Tier 1	328,751	286,561
Total	$ 411,102	$ 358,290
Classified as well capitalized ratio
Common equity Tier 1 capital ratio, Minimum Required to Be Considered Well-Capitalized, Ratio (as a percent)	6.50%	6.50%
Tier 1 leverage capital ratio (as a percent)	5.00%	5.00%
Risk-based capital:
Tier 1 (as a percent)	8.00%	8.00%
Total (as a percent)	10.00%	10.00%
BankRI
Bank actual capital amount
Common equity Tier 1 capital ratio, Actual, Amount	$ 209,670	$ 193,849
Tier 1 leverage capital	209,670	193,849
Risk-based capital:
Tier 1	209,670	193,849
Total risk-based capital	$ 227,674	$ 210,025
Bank actual capital ratio
Common equity Tier 1 capital ratio, Actual, Ratio (as a percent)	11.37%	11.38%
Tier 1 leverage capital ratio (as a percent)	9.35%	9.16%
Risk-based capital:
Tier 1 (as a percent)	11.37%	11.38%
Total (as a percent)	12.35%	12.33%
Minimum capital adequacy amount
Common equity Tier 1 capital ratio, Minimum Required for Capital Adequacy Purposes, Amount	$ 82,983	$ 76,654
Tier 1 leverage capital	89,698	84,650
Risk-based capital:
Tier 1	110,644	102,205
Total	$ 147,481	$ 136,269
Minimum capital adequacy ratio
Common equity Tier 1 capital ratio, Minimum Required for Capital Adequacy Purposes, Ratio (as a percent)	4.50%	4.50%
Tier 1 leverage capital ratio (as a percent)	4.00%	4.00%
Risk-based capital:
Tier 1 (as a percent)	6.00%	6.00%
Total (as a percent)	8.00%	8.00%
Minimum Required for Fully Phased in Capital Adequacy Purposes plus Capital Conservation Buffer
Common equity Tier 1 capital ratio	$ 129,084	$ 119,239
Tier 1 leverage capital ratio	89,698	84,650
Risk-based capital:
Tier 1 risk-based capital ratio	156,745	144,791
Total risk-based capital ratio	$ 193,569	$ 178,853
Minimum Required for Fully Phased in Capital Adequacy Purposes plus Capital Conservation Buffer
Common equity Tier 1 capital ratio (as a percent)	7.00%	7.00%
Tier 1 leverage capital ratio (as a percent)	4.00%	4.00%
Risk-based capital:
Tier 1 (as a percent)	8.50%	8.50%
Total (as a percent)	10.50%	10.50%
Classified as well capitalized
Common equity Tier 1 capital ratio, Minimum Required to Be Considered Well-Capitalized, Amount	$ 119,864	$ 110,722
Tier 1 leverage capital	112,123	105,813
Risk-based capital:
Tier 1	147,525	136,273
Total	$ 184,351	$ 170,337
Classified as well capitalized ratio
Common equity Tier 1 capital ratio, Minimum Required to Be Considered Well-Capitalized, Ratio (as a percent)	6.50%	6.50%
Tier 1 leverage capital ratio (as a percent)	5.00%	5.00%
Risk-based capital:
Tier 1 (as a percent)	8.00%	8.00%
Total (as a percent)	10.00%	10.00%
First Ipswich
Bank actual capital amount
Common equity Tier 1 capital ratio, Actual, Amount	$ 39,655	$ 37,502
Tier 1 leverage capital	39,655	37,502
Risk-based capital:
Tier 1	39,655	37,502
Total risk-based capital	$ 42,944	$ 40,625
Bank actual capital ratio
Common equity Tier 1 capital ratio, Actual, Ratio (as a percent)	13.91%	13.38%
Tier 1 leverage capital ratio (as a percent)	9.59%	9.44%
Risk-based capital:
Tier 1 (as a percent)	13.91%	13.38%
Total (as a percent)	15.06%	14.50%
Minimum capital adequacy amount
Common equity Tier 1 capital ratio, Minimum Required for Capital Adequacy Purposes, Amount	$ 12,829	$ 12,613
Tier 1 leverage capital	16,540	15,891
Risk-based capital:
Tier 1	17,105	16,817
Total	$ 22,812	$ 22,414
Minimum capital adequacy ratio
Common equity Tier 1 capital ratio, Minimum Required for Capital Adequacy Purposes, Ratio (as a percent)	4.50%	4.50%
Tier 1 leverage capital ratio (as a percent)	4.00%	4.00%
Risk-based capital:
Tier 1 (as a percent)	6.00%	6.00%
Total (as a percent)	8.00%	8.00%
Minimum Required for Fully Phased in Capital Adequacy Purposes plus Capital Conservation Buffer
Common equity Tier 1 capital ratio	$ 19,956	$ 19,620
Tier 1 leverage capital ratio	16,540	15,891
Risk-based capital:
Tier 1 risk-based capital ratio	24,232	23,824
Total risk-based capital ratio	$ 29,941	$ 29,418
Minimum Required for Fully Phased in Capital Adequacy Purposes plus Capital Conservation Buffer
Common equity Tier 1 capital ratio (as a percent)	7.00%	7.00%
Tier 1 leverage capital ratio (as a percent)	4.00%	4.00%
Risk-based capital:
Tier 1 (as a percent)	8.50%	8.50%
Total (as a percent)	10.50%	10.50%
Classified as well capitalized
Common equity Tier 1 capital ratio, Minimum Required to Be Considered Well-Capitalized, Amount	$ 18,530	$ 18,218
Tier 1 leverage capital	20,675	19,863
Risk-based capital:
Tier 1	22,807	22,423
Total	$ 28,515	$ 28,017
Classified as well capitalized ratio
Common equity Tier 1 capital ratio, Minimum Required to Be Considered Well-Capitalized, Ratio (as a percent)	6.50%	6.50%
Tier 1 leverage capital ratio (as a percent)	5.00%	5.00%
Risk-based capital:
Tier 1 (as a percent)	8.00%	8.00%
Total (as a percent)	10.00%	10.00%

Employee Benefit Plans (Rollfor

Employee Benefit Plans (Rollforward of Plan Assets and Benefit Obligation) (Details) - Health Insurance Postretirement Benefit - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in plan assets:
Fair value of plan assets at beginning of year	$ 0	$ 0	$ 0
Employer contributions	31	19	21
Benefits paid	(31)	(19)	(21)
Fair value of plan assets at end of year	0	0	0
Change in benefit obligation:
Benefit obligation at beginning of year	1,534	1,135	1,188
Service cost	70	49	48
Interest cost	59	43	45
Estimated benefits paid	(31)	(19)	(21)
Actuarial loss (gain)	(142)	326	(125)
Benefit obligation at end of year	1,490	1,534	1,135
Funded status at end of year	1,490	1,534	1,135
Accumulated benefit obligation at end of year	$ 1,490	$ 1,534	$ 1,135

Employee Benefit Plans (Compone

Employee Benefit Plans (Components of Net Periodic Postretirement Benefit Costs and Other Amounts Recognized in OCI) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Changes in postretirement benefit obligation recognized in other comprehensive income:
Total pre-tax changes in postretirement benefit obligation recognized in other comprehensive income	$ 121	$ (422)	$ 69
Health Insurance Postretirement Benefit
Net periodic benefit expense:
Service cost	70	49	48
Interest cost	59	43	45
Prior service credit	(21)	(21)	(21)
Actuarial gain	0	(47)	(42)
Net periodic benefit expense	108	24	30
Changes in postretirement benefit obligation recognized in other comprehensive income:
Net actuarial (loss) gain	142	(401)	90
Prior service credit	(21)	(21)	(21)
Total pre-tax changes in postretirement benefit obligation recognized in other comprehensive income	$ 121	$ (422)	$ 69

Employee Benefit Plans (Effects

Employee Benefit Plans (Effects of Changes in Assumed Healthcare Cost Trends) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Effect of 1% change in assumed health care cost trend rates
Effect of 1% increase on total service and interest cost components of net periodic postretirement benefit costs	$ 31
Effect of 1% decrease on total service and interest cost components of net periodic postretirement benefit costs	(24)
Effect of 1% increase on the accumulated postretirement benefit obligation	316
Effect of 1% decrease on the accumulated postretirement benefit obligation	$ (250)

Employee Benefit Plans (Activit

Employee Benefit Plans (Activity in Recognition and Retention Plans) (Details) - Restricted stock $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)$ / sharesshares
Restricted Stock Awards Outstanding
Outstanding at beginning of year (in shares) | shares	455,283
Granted (in shares) | shares	169,582
Vested (in shares) | shares	(195,660)
Forfeited / Canceled (in shares) | shares	(38,570)
Outstanding at end of year (in shares) | shares	390,635
Weighted Average Grant Price per Share
Outstanding at beginning of year (in dollars per share) | $ / shares	$ 12.64
Granted (in dollars per share) | $ / shares	18.40
Vested (in dollars per share) | $ / shares	12.53
Forfeited / Canceled (in dollars per share) | $ / shares	12.48
Outstanding at end of year (in dollars per share) | $ / shares	$ 15.21
Unrecognized compensation cost | $	$ 3,735
Weighted average remaining recognition period	22 months

Employee Benefit Plans (Activ_2

Employee Benefit Plans (Activity in Option Plans) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stock option activity
Outstanding at the beginning of the period (in shares)	50,000
Granted (in shares)	0	0	0
Exercised (in shares)	(45,000)
Forfeited/Canceled (in shares)	0
Outstanding at the end of the period (in shares)	5,000	50,000
Exercisable at the end of the period (in shares)	5,000
Stock Option Activity, Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 10.80
Granted (in dollars per share)	0
Exercised (in dollars per share)	10.90
Forfeited/Canceled (in dollars per share)	0
Outstanding at the end of the period (in dollars per share)	9.90	$ 10.80
Exercisable at the end of the period (in dollars per share)	$ 9.90
Stock Option Activity, Aggregate Intrinsic Value
Outstanding at the end of the period	$ 20
Exercisable at the end of the period	$ 20
Stock Option Activity, Weighted Average Contractual Term
Outstanding at the end of the period (in years)	1 year 9 months 18 days
Exercisable at the end of the period (in years)	1 year 9 months 18 days

Employee Benefit Plans (Narrati

Employee Benefit Plans (Narrative) (Details)	12 Months Ended
	Dec. 31, 2018USD ($)participantyrfinancial_institutionplanshares	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)shares
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Number of 401(k) plans administered | plan	1
Minimum employee age required to participate in the plan (in years) | yr	21
Expense for the company plan contributions	$ 3,200,000	$ 2,600,000	$ 2,800,000
Expense with deferred compensation plan	181,100	128,500	91,800
Accrued liabilities with deferred compensation plan	$ 5,500	$ 80,200	154,800
Unallocated shares | shares	109,950	142,332
Unallocated shares, aggregate cost	$ 599,000	$ 776,000
ESOP shares committed to be released	$ 543,000	$ 501,000	$ 395,000
Number of share-based compensation plans | plan	2
Granted (in shares) | shares	0	0	0
401(k) plan 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contribution as percentage of compensation of eligible employees	5.00%
Health Insurance Postretirement Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Aggregate benefits payable included in accrued expenses and other liabilities	$ 1,500,000	$ 1,500,000	$ 1,100,000
Discount rate used to determine the actuarial present value of projected postretirement benefit obligations (as a percent)	4.22%	3.62%	4.15%
Estimated prior service credit that will be amortized from accumulated other comprehensive income into net periodic benefit cost	$ 85,000
Assumed health care trend rates used in 2019 through 2023, high end of range (as a percent)	6.20%
Assumed health care trend rates used in 2019 through 2023, low end of range (as a percent)	5.30%
Ultimate health care trend rate after 2020 (as a percent)	4.50%
Expenses for benefits payable recognized under agreement	$ 108,000	$ 24,000	$ 30,000
Supplemental retirement plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Aggregate benefits payable included in accrued expenses and other liabilities	$ 12,100,000	12,000,000
Number of participants | participant	13
Expenses for benefits payable recognized under agreement	$ 500,000	$ 800,000
Discount rate used to determine the actuarial present value (as a percent)	4.00%	4.00%
Below age 65 | Health Insurance Postretirement Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Actual health care trend that will be used to measure the accumulated postretirement benefit obligation (as a percent)	3.10%
Actual health care trend used to measure the accumulated postretirement benefit obligation (as a percent)		(14.70%)
Over age 65 | Health Insurance Postretirement Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Actual health care trend that will be used to measure the accumulated postretirement benefit obligation (as a percent)	2.40%
Actual health care trend used to measure the accumulated postretirement benefit obligation (as a percent)		33.90%
Employee Stock Ownership Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
ESOP loan to purchase shares of entity's common stock | shares	546,986
Number of years during which quarterly installments are payable	30 years
Percentage of interest payable per annum on loan obtained by the ESOP	8.50%
Outstanding balance of loan	$ 1,000,000	$ 1,300,000
Unallocated shares | shares	109,950	142,332
Unallocated shares, aggregate cost	$ 600,000	$ 700,000
Unallocated shares, market value	1,500,000	$ 2,300,000
ESOP shares committed to be released	$ 500,000
Number of shares committed to be released to eligible employees | shares	32,382	34,356	36,372
2011 Restricted Stock Award Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Number of authorized shares | shares	500,000
Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Number of authorized shares | shares	1,750,000
Share-based compensation expense	$ 2,500,000	$ 2,300,000	$ 1,800,000
Tax benefits from vested awards	$ 1,200,000	700,000	300,000
Equity Incentive Plan 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Number of authorized shares | shares	1,750,000
Performance-based shares
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Number of financial institutions comprising peer group | financial_institution	17
Restricted stock
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Dividends paid on unvested shares recognized as compensation expense	$ 200,000	100,000	100,000
Stock Options
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Share-based compensation expense	$ 0	0	0
Exercisable period upon happening of a specific event, low end of range (in months)	3 months
Exercisable period upon happening of a specific event, high end of range (in years)	5 years
Dividend equivalent rights	$ 0	$ 0	$ 0
Vesting equally over three years | Time-based shares
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Percent of shares in tranche	50.00%
Award vesting period	3 years
Vesting percentage	33.00%
Vesting after achievement of performance targets | Performance-based shares
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Percent of shares in tranche	50.00%
Award vesting period	3 years

Fair Value of Financial Instr_3

Fair Value of Financial Instruments (Assets and Liabilities Recorded at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets:
AFS, debt securities, estimated fair value	$ 502,793	$ 539,142
Marketable equity securities		982
Investment securities available-for-sale		540,124
Equity securities held-for-trading	4,207	0
Derivatives	22,488	9,002
Liabilities:
Derivatives	22,220	8,940
GSE debentures
Assets:
AFS, debt securities, estimated fair value	181,079	149,924
GSE CMOs
Assets:
AFS, debt securities, estimated fair value	103,130	127,022
GSE MBSs
Assets:
AFS, debt securities, estimated fair value	165,089	189,313
SBA commercial loan asset-backed securities
Assets:
AFS, debt securities, estimated fair value	51	72
Corporate debt obligations
Assets:
AFS, debt securities, estimated fair value	39,708	62,683
U.S. treasury bonds
Assets:
AFS, debt securities, estimated fair value	13,736	8,730
Trust preferred securities
Assets:
AFS, debt securities, estimated fair value		1,398
Recurring basis
Assets:
AFS, debt securities, estimated fair value	502,793
Marketable equity securities		982
Investment securities available-for-sale		540,124
Equity securities held-for-trading	4,207
Liabilities:
Derivatives	22,013
Recurring basis | GSE debentures
Assets:
AFS, debt securities, estimated fair value	181,079	149,924
Recurring basis | GSE CMOs
Assets:
AFS, debt securities, estimated fair value	103,130	127,022
Recurring basis | GSE MBSs
Assets:
AFS, debt securities, estimated fair value	165,089	189,313
Recurring basis | SBA commercial loan asset-backed securities
Assets:
AFS, debt securities, estimated fair value	51	72
Recurring basis | Corporate debt obligations
Assets:
AFS, debt securities, estimated fair value	39,708	62,683
Recurring basis | U.S. treasury bonds
Assets:
AFS, debt securities, estimated fair value	13,736	8,730
Recurring basis | Trust preferred securities
Assets:
AFS, debt securities, estimated fair value		1,398
Recurring basis | Loan level derivatives
Assets:
Derivatives	22,013	8,865
Liabilities:
Derivatives		8,865
Recurring basis | Risk participation-out agreements
Assets:
Derivatives	344	65
Recurring basis | Risk participation-in agreements
Liabilities:
Derivatives	84	10
Recurring basis | Foreign exchange contracts
Assets:
Derivatives	131	72
Liabilities:
Derivatives	123	65
Recurring basis | Level 1
Assets:
AFS, debt securities, estimated fair value	0
Marketable equity securities		0
Investment securities available-for-sale		0
Equity securities held-for-trading	3,235
Liabilities:
Derivatives	0
Recurring basis | Level 1 | GSE debentures
Assets:
AFS, debt securities, estimated fair value	0	0
Recurring basis | Level 1 | GSE CMOs
Assets:
AFS, debt securities, estimated fair value	0	0
Recurring basis | Level 1 | GSE MBSs
Assets:
AFS, debt securities, estimated fair value	0	0
Recurring basis | Level 1 | SBA commercial loan asset-backed securities
Assets:
AFS, debt securities, estimated fair value	0	0
Recurring basis | Level 1 | Corporate debt obligations
Assets:
AFS, debt securities, estimated fair value	0	0
Recurring basis | Level 1 | U.S. treasury bonds
Assets:
AFS, debt securities, estimated fair value	0	0
Recurring basis | Level 1 | Trust preferred securities
Assets:
AFS, debt securities, estimated fair value		0
Recurring basis | Level 1 | Loan level derivatives
Assets:
Derivatives	0	0
Liabilities:
Derivatives		0
Recurring basis | Level 1 | Risk participation-out agreements
Assets:
Derivatives	0	0
Recurring basis | Level 1 | Risk participation-in agreements
Liabilities:
Derivatives	0	0
Recurring basis | Level 1 | Foreign exchange contracts
Assets:
Derivatives	0	0
Liabilities:
Derivatives	0	0
Recurring basis | Level 2
Assets:
AFS, debt securities, estimated fair value	502,793
Marketable equity securities		982
Investment securities available-for-sale		540,124
Equity securities held-for-trading	972
Liabilities:
Derivatives	22,013
Recurring basis | Level 2 | GSE debentures
Assets:
AFS, debt securities, estimated fair value	181,079	149,924
Recurring basis | Level 2 | GSE CMOs
Assets:
AFS, debt securities, estimated fair value	103,130	127,022
Recurring basis | Level 2 | GSE MBSs
Assets:
AFS, debt securities, estimated fair value	165,089	189,313
Recurring basis | Level 2 | SBA commercial loan asset-backed securities
Assets:
AFS, debt securities, estimated fair value	51	72
Recurring basis | Level 2 | Corporate debt obligations
Assets:
AFS, debt securities, estimated fair value	39,708	62,683
Recurring basis | Level 2 | U.S. treasury bonds
Assets:
AFS, debt securities, estimated fair value	13,736	8,730
Recurring basis | Level 2 | Trust preferred securities
Assets:
AFS, debt securities, estimated fair value		1,398
Recurring basis | Level 2 | Loan level derivatives
Assets:
Derivatives	22,013	8,865
Liabilities:
Derivatives		8,865
Recurring basis | Level 2 | Risk participation-out agreements
Assets:
Derivatives	344	65
Recurring basis | Level 2 | Risk participation-in agreements
Liabilities:
Derivatives	84	10
Recurring basis | Level 2 | Foreign exchange contracts
Assets:
Derivatives	131	72
Liabilities:
Derivatives	123	65
Recurring basis | Level 3
Assets:
AFS, debt securities, estimated fair value	0
Marketable equity securities		0
Investment securities available-for-sale		0
Equity securities held-for-trading	0
Liabilities:
Derivatives	0
Recurring basis | Level 3 | GSE debentures
Assets:
AFS, debt securities, estimated fair value	0	0
Recurring basis | Level 3 | GSE CMOs
Assets:
AFS, debt securities, estimated fair value	0	0
Recurring basis | Level 3 | GSE MBSs
Assets:
AFS, debt securities, estimated fair value	0	0
Recurring basis | Level 3 | SBA commercial loan asset-backed securities
Assets:
AFS, debt securities, estimated fair value	0	0
Recurring basis | Level 3 | Corporate debt obligations
Assets:
AFS, debt securities, estimated fair value	0	0
Recurring basis | Level 3 | U.S. treasury bonds
Assets:
AFS, debt securities, estimated fair value	0	0
Recurring basis | Level 3 | Trust preferred securities
Assets:
AFS, debt securities, estimated fair value		0
Recurring basis | Level 3 | Loan level derivatives
Assets:
Derivatives	0	0
Liabilities:
Derivatives		0
Recurring basis | Level 3 | Risk participation-out agreements
Assets:
Derivatives	0	0
Recurring basis | Level 3 | Risk participation-in agreements
Liabilities:
Derivatives	0	0
Recurring basis | Level 3 | Foreign exchange contracts
Assets:
Derivatives	0	0
Liabilities:
Derivatives	$ 0	$ 0

Fair Value of Financial Instr_4

Fair Value of Financial Instruments (Narrative) (Details)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Changes in generic pricing of securities period one, considered for analyzing changes in prices obtained from pricing service (in years)	15 years
Changes in generic pricing of securities period two, considered for analyzing changes in prices obtained from pricing service (in years)	30 years

Fair Value of Financial Instr_5

Fair Value of Financial Instruments (Assets and Liabilities Recorded at Fair Value on a Non-Recurring Basis) (Details) - Nonrecurring basis - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair value of assets and liabilities
Total assets measured at fair value on a non-recurring basis	$ 15,470	$ 25,614
Level 1
Fair value of assets and liabilities
Total assets measured at fair value on a non-recurring basis	0	0
Level 2
Fair value of assets and liabilities
Total assets measured at fair value on a non-recurring basis	965	1,184
Level 3
Fair value of assets and liabilities
Total assets measured at fair value on a non-recurring basis	14,505	24,430
Collateral-dependent impaired loans and leases
Fair value of assets and liabilities
Total assets measured at fair value on a non-recurring basis	11,451	21,195
Collateral-dependent impaired loans and leases | Level 1
Fair value of assets and liabilities
Total assets measured at fair value on a non-recurring basis	0	0
Collateral-dependent impaired loans and leases | Level 2
Fair value of assets and liabilities
Total assets measured at fair value on a non-recurring basis	0	0
Collateral-dependent impaired loans and leases | Level 3
Fair value of assets and liabilities
Total assets measured at fair value on a non-recurring basis	11,451	21,195
OREO
Fair value of assets and liabilities
Total assets measured at fair value on a non-recurring basis	3,054	3,235
OREO | Level 1
Fair value of assets and liabilities
Total assets measured at fair value on a non-recurring basis	0	0
OREO | Level 2
Fair value of assets and liabilities
Total assets measured at fair value on a non-recurring basis	0	0
OREO | Level 3
Fair value of assets and liabilities
Total assets measured at fair value on a non-recurring basis	3,054	3,235
Repossessed assets
Fair value of assets and liabilities
Total assets measured at fair value on a non-recurring basis	965	1,184
Repossessed assets | Level 1
Fair value of assets and liabilities
Total assets measured at fair value on a non-recurring basis	0	0
Repossessed assets | Level 2
Fair value of assets and liabilities
Total assets measured at fair value on a non-recurring basis	965	1,184
Repossessed assets | Level 3
Fair value of assets and liabilities
Total assets measured at fair value on a non-recurring basis	$ 0	$ 0

Fair Value of Financial Instr_6

Fair Value of Financial Instruments (Repossessed Assets) (Details) - Level 3 - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Recurring basis | Collateral-dependent impaired loans and leases | Appraisal of collateral
Quantitative information for Level 3 Fair Value Measurements Assets
Fair value of assets	$ 11,451	$ 18,091
Recurring basis | Other real estate owned | Appraisal of collateral
Quantitative information for Level 3 Fair Value Measurements Assets
Fair value of assets	$ 3,054	$ 3,235
Minimum | Discount for Costs to Sell
Quantitative information for Level 3 Fair Value Measurements Assets
Fair value inputs, basis spread (as a percent)	0.00%
Minimum | Appraisal Adjustments
Quantitative information for Level 3 Fair Value Measurements Assets
Fair value inputs, basis spread (as a percent)	0.00%
Maximum | Discount for Costs to Sell
Quantitative information for Level 3 Fair Value Measurements Assets
Fair value inputs, basis spread (as a percent)	10.00%
Maximum | Appraisal Adjustments
Quantitative information for Level 3 Fair Value Measurements Assets
Fair value inputs, basis spread (as a percent)	15.00%

Fair Value of Financial Instr_7

Fair Value of Financial Instruments (Summary of Estimated Fair Values of Financial Instruments) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financial assets:
Investment securities held-to-maturity:	$ 112,830	$ 108,523
Loans and leases, net	6,244,824	5,672,087
Restricted equity securities	61,751	59,369
Financial liabilities:
Certificates of deposit	1,789,165	1,207,470
Borrowed funds	52,734	47,639
Level 1
Financial assets:
Loans held-for-sale	0	0
Loans and leases, net	0	0
Restricted equity securities	0	0
Financial liabilities:
Certificates of deposit	0	0
Borrowed funds	0	0
Level 2
Financial assets:
Loans held-for-sale	3,247	2,628
Loans and leases, net	0	0
Restricted equity securities	0	0
Financial liabilities:
Certificates of deposit	1,778,860	1,198,201
Borrowed funds	886,545	995,335
Level 3
Financial assets:
Loans held-for-sale	0	0
Loans and leases, net	6,154,704	5,594,543
Restricted equity securities	61,751	59,369
Financial liabilities:
Certificates of deposit	0	0
Borrowed funds	0	0
Carrying Value
Financial assets:
Loans held-for-sale	3,247	2,628
Loans and leases, net	6,244,824	5,672,087
Restricted equity securities	61,751	59,369
Financial liabilities:
Certificates of deposit	1,789,165	1,207,470
Borrowed funds	920,542	1,020,819
Estimated Fair Value
Financial assets:
Loans held-for-sale	3,247	2,628
Loans and leases, net	6,154,704	5,594,543
Restricted equity securities	61,751	59,369
Financial liabilities:
Certificates of deposit	1,778,860	1,198,201
Borrowed funds	886,545	995,335
GSE debentures
Financial assets:
Investment securities held-to-maturity:	49,601	40,801
GSE debentures | Level 1
Financial assets:
Investment securities held-to-maturity:	0	0
GSE debentures | Level 2
Financial assets:
Investment securities held-to-maturity:	49,601	40,801
GSE debentures | Level 3
Financial assets:
Investment securities held-to-maturity:	0	0
GSE debentures | Carrying Value
Financial assets:
Investment securities held-to-maturity:	50,546	41,612
GSE debentures | Estimated Fair Value
Financial assets:
Investment securities held-to-maturity:	49,601	40,801
GSE MBSs
Financial assets:
Investment securities held-to-maturity:	11,131	13,705
GSE MBSs | Level 1
Financial assets:
Investment securities held-to-maturity:	0	0
GSE MBSs | Level 2
Financial assets:
Investment securities held-to-maturity:	11,131	13,705
GSE MBSs | Level 3
Financial assets:
Investment securities held-to-maturity:	0	0
GSE MBSs | Carrying Value
Financial assets:
Investment securities held-to-maturity:	11,426	13,923
GSE MBSs | Estimated Fair Value
Financial assets:
Investment securities held-to-maturity:	11,131	13,705
Municipal obligations
Financial assets:
Investment securities held-to-maturity:	51,598	53,517
Municipal obligations | Level 1
Financial assets:
Investment securities held-to-maturity:	0	0
Municipal obligations | Level 2
Financial assets:
Investment securities held-to-maturity:	51,598	53,517
Municipal obligations | Level 3
Financial assets:
Investment securities held-to-maturity:	0	0
Municipal obligations | Carrying Value
Financial assets:
Investment securities held-to-maturity:	52,304	53,695
Municipal obligations | Estimated Fair Value
Financial assets:
Investment securities held-to-maturity:	51,598	53,517
Foreign government obligations
Financial assets:
Investment securities held-to-maturity:	500	500
Foreign government obligations | Level 1
Financial assets:
Investment securities held-to-maturity:	0	0
Foreign government obligations | Level 2
Financial assets:
Investment securities held-to-maturity:	0	0
Foreign government obligations | Level 3
Financial assets:
Investment securities held-to-maturity:	500	500
Foreign government obligations | Carrying Value
Financial assets:
Investment securities held-to-maturity:	500	500
Foreign government obligations | Estimated Fair Value
Financial assets:
Investment securities held-to-maturity:	$ 500	$ 500

Condensed Parent Company Fina_3

Condensed Parent Company Financial Statements (Condensed Balance Sheets) (Details) - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
ASSETS
Cash and due from banks		$ 47,542	$ 25,622
Short-term investments		42,042	35,383
Total cash and cash equivalents		89,584	61,005	$ 67,657	$ 75,489
Equity securities held-for-trading		4,207	0
Restricted equity securities		61,751	59,369
Premises and equipment, net		76,382	80,283
Deferred tax asset		21,495	15,061
Goodwill		160,427	137,890	137,890	137,890
Other assets	[1]	103,214	91,609
Total assets		7,392,805	6,780,249
LIABILITIES AND STOCKHOLDERS' EQUITY
Borrowed funds		920,542	1,020,819
Accrued expenses and other liabilities		100,174	67,818
Total liabilities		6,482,186	5,967,666
Stockholders' Equity:
Common stock, $0.01 par value; 200,000,000 shares authorized; 85,177,172 shares issued and 81,695,695 shares issued, respectively		852	817
Additional paid-in capital		755,629	699,976
Retained earnings, partially restricted	[1]	212,838	161,217
Accumulated other comprehensive loss		(9,460)	(5,950)
Treasury stock, at cost; 5,020,025 shares and 4,440,665 shares, respectively		(59,120)	(51,454)
Unallocated common stock held by ESOP; 109,950 shares and 142,332 shares, respectively		(599)	(776)
Total Brookline Bancorp, Inc. stockholders' equity	[1]	900,140	803,830
Total liabilities and stockholders' equity	[1]	7,392,805	6,780,249
Parent Company
ASSETS
Cash and due from banks		33,663	5,511
Short-term investments		33	32
Total cash and cash equivalents		33,696	5,543	$ 32,252	$ 28,103
Equity securities held-for-trading		3,235	0
ESOP loan to Brookline Bank		1,002	1,252
Intercompany loan to Brookline Bank		40,000	80,000
Restricted equity securities		101	100
Premises and equipment, net		4,318	6,032
Deferred tax asset		1,499	0
Investment in subsidiaries, at equity		864,798	753,056
Goodwill		35,267	35,267
Other assets		5,400	6,627
Total assets		989,316	887,877
LIABILITIES AND STOCKHOLDERS' EQUITY
Borrowed funds		83,433	83,271
Deferred tax liability		0	608
Accrued expenses and other liabilities		5,743	168
Total liabilities		89,176	84,047
Stockholders' Equity:
Common stock, $0.01 par value; 200,000,000 shares authorized; 85,177,172 shares issued and 81,695,695 shares issued, respectively		852	817
Additional paid-in capital		755,629	699,976
Retained earnings, partially restricted		212,838	161,217
Accumulated other comprehensive loss		(9,460)	(5,950)
Treasury stock, at cost; 5,020,025 shares and 4,440,665 shares, respectively		(59,120)	(51,454)
Unallocated common stock held by ESOP; 109,950 shares and 142,332 shares, respectively		(599)	(776)
Total Brookline Bancorp, Inc. stockholders' equity		900,140	803,830
Total liabilities and stockholders' equity		$ 989,316	$ 887,877
[1]	Previously reported amounts prior to January 1, 2015 have been restated to reflect a retrospective change in accounting principle for investments in qualified affordable housing projects, in accordance with ASU 2014-01. Refer to Note 10, "Other Assets".

Condensed Parent Company Fina_4

Condensed Parent Company Financial Statements (Condensed Balance Sheets (Additional Information)) (Details) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Condensed Balance Sheet Statements, Captions [Line Items]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	85,177,172	81,695,695
Treasury stock, shares	5,020,025	4,440,665
Unallocated common stock held by ESOP, shares	109,950	142,332
Parent Company
Condensed Balance Sheet Statements, Captions [Line Items]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	85,177,172	81,695,695
Treasury stock, shares	5,020,025	4,440,665
Unallocated common stock held by ESOP, shares	109,950	142,332

Condensed Parent Company Fina_5

Condensed Parent Company Financial Statements (Condensed Income Statements) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest and dividend income:
Marketable and restricted equity securities									$ 3,964	$ 3,062	$ 2,975
Total interest and dividend income	$ 83,544	$ 80,636	$ 78,074	$ 71,639	$ 68,337	$ 67,176	$ 65,186	$ 62,351	313,893	263,050	239,648
Interest expense:
Net interest income	63,159	62,332	62,717	59,491	57,657	56,843	55,583	53,098	247,699	223,181	203,664
Gain on investment securities, net	(692)	(243)	0	1,162	0	0	0	11,393	227	11,393	0
Non-interest income:
Other									5,847	4,789	4,683
Total non-interest income									25,224	32,173	22,667
Non-interest expense:
Compensation and employee benefits									91,535	82,413	77,836
Occupancy									14,991	14,546	13,882
Equipment and data processing									18,213	16,854	15,496
Professional services									4,404	4,315	3,852
Advertising and marketing									4,016	3,369	3,381
Merger and acquisition expense									3,787	411	0
Other	39,745	36,773	37,163	39,471	34,633	34,889	34,276	33,224	13,484	11,788	10,083
Total non-interest expense									155,232	139,111	130,362
Credit for income taxes	7,055	6,140	7,342	5,652	18,712	8,330	8,759	7,835	26,189	43,636	30,392
Net income attributable to Brookline Bancorp, Inc.	$ 21,138	$ 22,460	$ 20,831	$ 18,633	$ 6,827	$ 15,366	$ 14,880	$ 13,445	83,062	50,518	52,362
Parent Company
Interest and dividend income:
Dividend income from subsidiaries									0	7,317	109
Marketable and restricted equity securities									37	0	0
ESOP loan to Brookline Bank									98	120	141
Intercompany loan to Brookline Bank									1,722	532	0
Total interest and dividend income									1,857	7,969	250
Interest expense:
Borrowed funds									5,223	5,123	5,080
Net interest income									(3,366)	2,846	(4,830)
Gain on investment securities, net									71	0	0
Non-interest income:
Other									16	0	15
Total non-interest income									87	0	15
Non-interest expense:
Compensation and employee benefits									345	391	82
Occupancy									1,586	1,584	1,582
Equipment and data processing									(798)	(1,011)	(1,190)
Directors' fees									417	453	700
Franchise taxes									321	180	180
Insurance									534	528	490
Professional services									364	470	245
Advertising and marketing									19	4	0
Merger and acquisition expense									452	411	0
Other									(1,140)	(1,224)	(1,300)
Total non-interest expense									2,100	1,786	789
Loss before income taxes									(5,379)	1,060	(5,604)
Credit for income taxes									(1,976)	(1,944)	(1,779)
Loss before equity in undistributed income of subsidiaries									(3,403)	3,004	(3,825)
Equity in undistributed income of subsidiaries									86,465	47,514	56,187
Net income attributable to Brookline Bancorp, Inc.									$ 83,062	$ 50,518	$ 52,362

Condensed Parent Company Fina_6

Condensed Parent Company Financial Statements (Condensed Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income attributable to Brookline Bancorp, Inc.	$ 21,138	$ 22,460	$ 20,831	$ 18,633	$ 6,827	$ 15,366	$ 14,880	$ 13,445	$ 83,062	$ 50,518	$ 52,362
Adjustments to reconcile net income to net cash provided from operating activities:
Depreciation of premises and equipment									7,382	7,232	7,080
Amortization of debt issuance costs									100	100	101
Equity securities held-for-trading									(5,371)	0	0
Net cash provided from operating activities									123,029	84,947	77,930
Cash flows from investing activities:
Purchase of restricted equity securities									(13,262)	(7,927)	(4,017)
Purchase of premises and equipment									(3,352)	(11,557)	(5,262)
Net cash used for investing activities									(588,022)	(383,974)	(427,795)
Cash flows from financing activities:
Proceeds from issuance of common stock									0	81,943	0
Common stock issued for acquisition									55,182	0	0
Payment of dividends on common stock									(31,441)	(27,035)	(25,366)
Net cash provided from financing activities									493,572	292,375	342,033
Net increase (decrease) in cash and cash equivalents									28,579	(6,652)	(7,832)
Cash and cash equivalents at beginning of year				61,005				67,657	61,005	67,657	75,489
Cash and cash equivalents at end of year	89,584				61,005				89,584	61,005	67,657
Supplemental disclosures of cash flow information:
Fair value of assets acquired, net of cash and cash equivalents acquired									292,025	0	0
Fair value of liabilities assumed									278,988	0	0
Parent Company
Cash flows from operating activities:
Net income attributable to Brookline Bancorp, Inc.									83,062	50,518	52,362
Adjustments to reconcile net income to net cash provided from operating activities:
Equity in undistributed income of subsidiaries									(86,465)	(47,514)	(56,187)
Depreciation of premises and equipment									3,073	2,856	2,735
Amortization of debt issuance costs									100	100	101
Equity securities held-for-trading									(3,235)	0	0
Other operating activities, net									(31,014)	(5,885)	30,895
Net cash provided from operating activities									(34,479)	75	29,906
Cash flows from investing activities:
Repayment of ESOP loan by Brookline Bank									250	250	250
Pay down (issuance) of intercompany loan to Brookline Bank									40,000	(80,000)	0
Purchase of restricted equity securities									(1)	0	0
Purchase of premises and equipment									(1,359)	(1,942)	(641)
Net cash used for investing activities									38,890	(81,692)	(391)
Cash flows from financing activities:
Proceeds from issuance of common stock									0	81,943	0
Common stock issued for acquisition									55,183	0	0
Payment of dividends on common stock									(31,441)	(27,035)	(25,366)
Net cash provided from financing activities									23,742	54,908	(25,366)
Net increase (decrease) in cash and cash equivalents									28,153	(26,709)	4,149
Cash and cash equivalents at beginning of year				$ 5,543				$ 32,252	5,543	32,252	28,103
Cash and cash equivalents at end of year	$ 33,696				$ 5,543				33,696	5,543	32,252
Supplemental disclosures of cash flow information:
Fair value of assets acquired, net of cash and cash equivalents acquired									292,025	0	0
Fair value of liabilities assumed									$ 278,988	$ 0	$ 0

Quarterly Results of Operatio_3

Quarterly Results of Operations (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Interest and dividend income	$ 83,544	$ 80,636	$ 78,074	$ 71,639	$ 68,337	$ 67,176	$ 65,186	$ 62,351	$ 313,893	$ 263,050	$ 239,648
Interest expense	20,385	18,304	15,357	12,148	10,680	10,333	9,603	9,253	66,194	39,869	35,984
Net interest income	63,159	62,332	62,717	59,491	57,657	56,843	55,583	53,098	247,699	223,181	203,664
Provision for credit losses	123	2,717	1,470	641	1,802	2,911	873	13,402	4,951	18,988	10,353
Net interest income after provision for credit losses	63,036	59,615	61,247	58,850	55,855	53,932	54,710	39,696	242,748	204,193	193,311
Loan level derivative income, net	1,811	2,192	571	866	755	844	186	402	5,440	2,187	3,962
(Loss) gain on investment securities, net	(692)	(243)	0	1,162	0	0	0	11,393	227	11,393	0
Gain on sales of loans and leases held-for-sale	327	535	722	299	935	1,049	307	353	1,883	2,644	3,256
Other non-interest income	5,015	4,585	4,233	3,841	4,125	4,080	3,984	3,760
Amortization of identified intangible assets	(537)	(537)	(539)	(467)	(519)	(519)	(519)	(532)	(2,080)	(2,089)	(2,500)
Other non-interest expense	(39,745)	(36,773)	(37,163)	(39,471)	(34,633)	(34,889)	(34,276)	(33,224)	(13,484)	(11,788)	(10,083)
Income before provision for income taxes	29,215	29,374	29,071	25,080	26,518	24,497	24,392	21,848	112,740	97,255	85,616
Provision for income taxes	7,055	6,140	7,342	5,652	18,712	8,330	8,759	7,835	26,189	43,636	30,392
Net income before noncontrolling interest in subsidiary	22,160	23,234	21,729	19,428	7,806	16,167	15,633	14,013	86,551	53,619	55,224
Less net income attributable to noncontrolling interest in subsidiary	1,022	774	898	795	979	801	753	568	3,489	3,101	2,862
Net income attributable to Brookline Bancorp, Inc.	$ 21,138	$ 22,460	$ 20,831	$ 18,633	$ 6,827	$ 15,366	$ 14,880	$ 13,445	$ 83,062	$ 50,518	$ 52,362
Earnings per share:
Basic (in dollars per share)	$ 0.26	$ 0.28	$ 0.26	$ 0.24	$ 0.09	$ 0.20	$ 0.20	$ 0.19	$ 1.04	$ 0.68	$ 0.74
Diluted (in dollars per share)	$ 0.26	$ 0.28	$ 0.26	$ 0.24	$ 0.09	$ 0.20	$ 0.20	$ 0.19	$ 1.04	$ 0.68	$ 0.74
Average common shares outstanding:
Basic (in shares)	80,258,489	80,315,050	80,184,977	77,879,593	76,583,712	76,452,539	74,325,013	70,386,766	79,669,668	74,459,508	70,261,954
Diluted (in shares)	80,407,558	80,515,467	80,505,614	78,167,800	76,868,307	76,961,948	74,810,088	70,844,096	79,909,251	74,811,408	70,444,083
Common stock price:
High (in dollars per share)	$ 16.97	$ 19.05	$ 19.25	$ 17.05	$ 16.35	$ 15.50	$ 15.95	$ 16.75
Low (in dollars per share)	12.86	16.70	15.90	15.60	14.50	13.75	13.75	14.50
Dividends paid:
Dividends per share (in dollars per share)	$ 0.105	$ 0.100	$ 0.100	$ 0.090	$ 0.090	$ 0.090	$ 0.090	$ 0.090

Subsequent Events (Narrative) (

Subsequent Events (Narrative) (Details) - USD ($)	Jan. 04, 2019	Jan. 30, 2019	Dec. 31, 2018	Dec. 05, 2018	Feb. 04, 2016
Subsequent Event [Line Items]
Stock repurchase program, authorized amount				$ 10,000,000	$ 10,000,000
Subsequent Event
Subsequent Event [Line Items]
Stock repurchase program, authorized amount		$ 10,000,000
Brookline Bank | Subsequent Event
Subsequent Event [Line Items]
Percentage of voting interest acquired	1593.00%
Payments to acquired additional interest in subsidiaries	$ 35,900,000
Brookline Bank
Subsequent Event [Line Items]
Ownership percentage by noncontrolling owners			8407.00%