Blue Hills Bancorp (BHBK) 10-K 7 Mar 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Mar. 02, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	Blue Hills Bancorp, Inc.
Entity Central Index Key	1,601,545
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus (Q1,Q2,Q3,FY)	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		26,859,423
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 431,133,000

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets
Cash and due from banks	$ 16,149	$ 14,752
Short-term investments	30,018	15,744
Total cash and cash equivalents	46,167	30,496
Securities available for sale, at fair value	9,720	204,836
Securities held to maturity, at amortized cost	303,716	201,027
Federal Home Loan Bank stock, at cost	12,105	13,352
Loans held for sale	8,992	2,761
Loans, net of allowance for loan losses of $20,877 in 2017 and $18,750 in 2016	2,186,147	1,912,871
Premises and equipment, net	21,573	22,034
Accrued interest receivable	6,438	6,057
Goodwill	9,160	9,160
Core deposit intangible	557	1,400
Net deferred tax asset	6,000	10,146
Bank-owned life insurance	33,078	32,015
Other assets	24,867	23,537
Assets	2,668,520	2,469,692
Deposits:
Non-interest bearing	219,984	184,982
Interest bearing	1,819,885	1,623,705
Total deposits	2,039,869	1,808,687
Short-term borrowings	100,000	146,000
Long-term debt	105,000	105,000
Accrued expenses and other liabilities	25,845	23,098
Total liabilities	2,270,714	2,082,785
Commitments and contingencies (Notes 1, 4 and 13)
Stockholders' Equity:
Preferred stock, zero par value, (50,000,000 shares authorized; none issued and outstanding)	0	0
Common stock, $0.01 par value; 100,000,000 shares authorized, 26,827,660 and 26,759,953 issued and outstanding at December 31, 2017 and 2016, respectively	268	268
Additional paid-in capital	254,750	249,308
Unearned compensation- ESOP	(19,737)	(20,496)
Retained earnings	163,978	161,896
Accumulated other comprehensive loss	(1,453)	(4,069)
Total stockholders' equity	397,806	386,907
Total liabilities and stockholders' equity	$ 2,668,520	$ 2,469,692

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Allowance for loan losses	$ 20,877	$ 18,750
Preferred stock, par value (dollars per share)	$ 0	$ 0
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	26,827,660	26,759,953
Common stock, shares outstanding	26,827,660	26,759,953

Consolidated Statements of Net

Consolidated Statements of Net Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest and dividend income:
Interest and fees on loans	$ 76,701	$ 58,953	$ 45,342
Interest on securities	7,110	8,895	8,828
Dividends	733	1,596	4,068
Other	231	94	63
Total interest and dividend income	84,775	69,538	58,301
Interest expense:
Interest on deposits	15,215	10,488	7,527
Interest on borrowings	2,523	2,088	1,217
Total interest expense	17,738	12,576	8,744
Net interest and dividend income	67,037	56,962	49,557
Provision for loan losses	2,098	4,885	4,090
Net interest and dividend income, after provision for loan losses	64,939	52,077	45,467
Noninterest income:
Deposit account fees	1,418	1,327	1,314
Interchange and ATM fees	1,609	1,546	1,511
Mortgage banking	3,657	2,473	282
Loss on sale of purchased home equity portfolio	(118)	0	0
Loan level derivative fee income	2,792	2,371	2,120
Gains (losses) on sales and calls of securities, net	(94)	1,280	1,968
Gain on exchange of investment in Northeast Retirement Services	5,947	0	0
Bank-owned life insurance income	1,063	1,048	1,031
Bank-owned life insurance death benefit gains	0	506	0
Miscellaneous	808	1,576	453
Total noninterest income	17,082	12,127	8,679
Noninterest expense:
Salaries and employee benefits	31,278	28,853	22,570
Occupancy and equipment	8,393	7,370	6,267
Data processing	4,149	3,460	3,510
Professional fees	2,275	2,638	2,689
Advertising	1,922	2,423	2,458
FDIC deposit insurance	881	1,125	999
Directors’ fees	1,566	1,458	644
Amortization of core deposit intangible	843	1,225	1,607
Other general and administrative	2,999	3,194	3,338
Total noninterest expense	54,306	51,746	44,082
Income before income taxes	27,715	12,458	10,064
Provision for income taxes	11,226	3,805	2,837
Net income	$ 16,489	$ 8,653	$ 7,227
Earnings per common share:
Basic earnings per share (dollars per share)	$ 0.69	$ 0.35	$ 0.28
Diluted earnings per share (dollars per share)	$ 0.67	$ 0.35	$ 0.28
Weighted average shares outstanding:
Weighted average common shares (basic) (shares)	23,985,822	24,420,405	26,064,947
Weighted average common shares (diluted) (shares)	24,482,414	24,540,929	26,069,589

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income		$ 16,489	$ 8,653	$ 7,227
Securities available for sale:
Change in unrealized holding gains (losses)		3,276	3,849	(8,332)
Reclassification adjustment for net gains realized in net income	[1]	94	(1,235)	(1,968)
Reclassification of unrealized gains on securities transferred to held to maturity		0	0	(666)
Net unrealized gains (losses)		3,370	2,614	(10,966)
Tax effect		(1,147)	(938)	3,818
Net-of-tax amount		2,223	1,676	(7,148)
Reclassification of unrealized gains on securities transferred from available for sale		0	0	666
Amortization of amounts previously recorded upon transfer to held-to-maturity from available-for-sale	[2]	(87)	(234)	(95)
Net change in unrealized gains		(87)	(234)	571
Tax effect		48	83	(197)
Net-of-tax amount		(39)	(151)	374
Defined benefit pension plan:
Gains (losses) arising during the period		491	(895)	(1,610)
Reclassification adjustments for losses (gains) recognized in net periodic benefit cost	[3]	297	271	110
Net gains (losses)		788	(624)	(1,500)
Tax effect		(356)	218	509
Net-of-tax amount		432	(406)	(991)
Other comprehensive income (loss)		2,616	1,119	(7,765)
Comprehensive income (loss)		$ 19,105	$ 9,772	$ (538)
[1]	Amounts are included in gains on sales and calls of securities, net and net impairment losses, in noninterest income in the consolidated statements of net income. Income tax expense (benefit) associated with the reclassification adjustment for the years ended December 31, 2017, 2016 and 2015 was approximately $(32,000), $431,000 and $691,000, respectively.
[2]	Amounts are included in interest income on securities in the consolidated statements of net income. Income tax expense associated with the amortization amount for the years ended December 31, 2017, 2016 and 2015 was $48,000, $83,000, and $35,000, respectively.
[3]	Amounts are included in salaries and employee benefits, in noninterest expense in the consolidated statements of net income. Income tax benefit associated with the reclassification adjustment for the years ended December 31, 2017, 2016 and 2015 was $121,000, $97,000 and $37,000, respectively.

Consolidated Statements of Com6

Consolidated Statements of Comprehensive Income (Loss) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Reclassification adjustment for net gains realized in net income, tax	$ (32)	$ 431	$ 691
Other comprehensive (income) loss, amortization adjustment from AOCI, held-to-maturities, tax	48	83	35
Other comprehensive income (loss), reclassification adjustment and other postretirement benefit plans, for net gain (loss), tax expense (benefit)	$ 121	$ 97	$ 37

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional paid-in capital	Unearned Compensation- ESOP	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2014	$ 411,606	$ 285	$ 281,035	$ (22,014)	$ 149,723	$ 2,577
Beginning balance (in shares) at Dec. 31, 2014		28,466,813
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	(538)				7,227	(7,765)
ESOP shares committed to be released	1,063		304	759
Common stock dividends declared	(1,032)				(1,032)
Repurchase of common stock	(13,121)	$ (10)	(13,111)
Repurchase of common stock (in shares)		(929,300)
Share redemption for tax withholdings on deferred compensation obligation and restricted stock vesting	(439)		(439)
Share redemption for tax withholdings on deferred compensation obligation and restricted stock vesting (in shares)		(27,956)
Restricted stock awards granted	0	$ 10	(10)
Restricted stock awards granted (in shares)		983,175
Stock based compensation expenses	1,124		1,124
Excess tax benefit from deferred compensation obligation and stock based compensation	166		166
Ending balance at Dec. 31, 2015	398,829	$ 285	269,069	(21,255)	155,918	(5,188)
Ending balance (in shares) at Dec. 31, 2015		28,492,732
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	9,772				8,653	1,119
ESOP shares committed to be released	1,130		371	759
Common stock dividends declared	(2,675)				(2,675)
Repurchase of common stock	(24,432)	$ (17)	(24,415)
Repurchase of common stock (in shares)		(1,708,340)
Share redemption for tax withholdings on deferred compensation obligation and restricted stock vesting	(730)		(730)
Share redemption for tax withholdings on deferred compensation obligation and restricted stock vesting (in shares)		(46,969)
Restricted stock awards granted	0	$ 0	0
Restricted stock awards granted (in shares)		31,450
Restricted stock awards forfeited (in shares)		(11,800)
Stock based compensation expenses	4,868		4,868
Excess tax benefit from deferred compensation obligation and stock based compensation	105		105
Proceeds from exercise of options (in shares)		2,880
Proceeds from exercise of options	40		40
Ending balance at Dec. 31, 2016	386,907	$ 268	249,308	(20,496)	161,896	(4,069)
Ending balance (in shares) at Dec. 31, 2016		26,759,953
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of change in accounting principle (Note 1)			27		(27)
Comprehensive income	19,105				16,489	2,616
ESOP shares committed to be released	1,431		672	759
Common stock dividends declared	(14,380)				(14,380)
Share redemption for tax withholdings on deferred compensation obligation and restricted stock vesting	(983)		(983)
Share redemption for tax withholdings on deferred compensation obligation and restricted stock vesting (in shares)		(49,141)
Restricted stock awards granted	1	$ 1
Restricted stock awards granted (in shares)		184,695
Restricted stock awards forfeited (in shares)		(85,317)
Restricted stock awards forfeited	(1)	$ (1)
Stock based compensation expenses	$ 5,483
Proceeds from exercise of options (in shares)	17,470	17,470
Proceeds from exercise of options	$ 243		243
Ending balance at Dec. 31, 2017	$ 397,806	$ 268	$ 254,750	$ (19,737)	$ 163,978	$ (1,453)
Ending balance (in shares) at Dec. 31, 2017		26,827,660

Consolidated Statements of Cha8

Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Common stock dividends declared (dollars per share)	$ 0.60	$ 0.11	$ 0.04

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income	$ 16,489	$ 8,653	$ 7,227
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for loan losses	2,098	4,885	4,090
Net amortization of securities	1,650	2,924	3,710
Losses (gains) on sales and calls of securities, net	94	(1,280)	(1,968)
Net change in loans held for sale	(6,231)	(1,106)	(374)
Losses (gains) on sales of residential portfolio loans, net	(54)	(319)	44
Loss on sale of purchased home equity portfolio	118	0	0
Loss on sale of foreclosed property	7	0	0
Net amortization of deferred loan origination costs and discounts	11	(374)	100
Depreciation and amortization of premises and equipment	2,120	2,011	1,824
Amortization of core deposit intangible	843	1,225	1,607
Bank-owned life insurance income, including death benefit gains	(1,063)	(1,554)	(1,031)
ESOP expense	1,431	1,130	1,063
Deferred income tax provision (benefit)	2,691	(118)	(302)
Stock based compensation expense	5,483	4,868	1,124
Excess tax benefit from deferred and stock based compensation	0	105	166
Gain on exchange of investment in Northeast Retirement Services	(5,947)	0	0
Net change in:
Accrued interest receivable	(381)	(713)	(911)
Other assets	(2,545)	(3,477)	(1,153)
Accrued expenses and other liabilities	2,882	809	(8,661)
Net cash provided by operating activities	19,696	17,669	6,555
Activity in securities available for sale:
Purchases	(13,951)	(76,512)	(153,222)
Sales	213,084	97,824	99,522
Maturities/calls	0	4,133	5,632
Principal paydowns	5,049	3,497	24,487
Activity in securities held to maturity:
Purchases	(167,591)	(59,939)	(23,361)
Maturities/calls	30,000	22,835	9,000
Principal paydowns	33,595	34,866	10,421
Loan originations and purchases, net of paydowns	(339,412)	(403,729)	(400,115)
Proceeds from sale of foreclosed property	195	0	0
Net purchases of premises and equipment	(1,659)	(4,030)	(3,051)
Purchases of FHLBB stock	(9,353)	(5,487)	(3,296)
Redemption of FHLBB stock	10,600	5,702	1,431
Proceeds from exchange of investment in Northeast Retirement Services	1,595	0	0
Proceeds from bank-owned life insurance death benefits	0	1,165	0
Net cash used in investing activities	(174,087)	(358,512)	(424,944)
Cash flows from financing activities:
Net change in deposits, excluding brokered	189,495	252,295	124,670
Net change in brokered deposits	41,687	122,543	96,463
Net change in short-term borrowings	(46,000)	(59,000)	165,000
Repayments of long-term debt	(45,000)	(20,000)	0
Proceeds from long-term debt	45,000	70,000	20,000
Repurchase of common stock	0	(24,432)	(13,121)
Share redemption for tax withholdings on deferred compensation obligation	0	0	(439)
Share redemption for tax withholdings for restricted stock vesting	(983)	(730)	0
Proceeds from exercise of stock options	243	40	0
Common stock dividends paid	(14,380)	(2,675)	(1,032)
Net cash provided by financing activities	170,062	338,041	391,541
Net change in cash and cash equivalents	15,671	(2,802)	(26,848)
Cash and cash equivalents at beginning of year	30,496	33,298	60,146
Cash and cash equivalents at end of year	46,167	30,496	33,298
Supplementary information:
Interest paid	17,358	12,378	8,700
Income taxes paid, net of refunds	7,674	4,390	4,280
Securities transferred from available-for-sale to held-to-maturity	0	0	196,958
Portfolio loans transferred to loans held for sale designation	0	0	11,222
1-4 Family Residential
Activity in securities held to maturity:
Proceeds from sales of portfolios	51,661	21,163	7,608
Home Equity
Activity in securities held to maturity:
Proceeds from sales of portfolios	$ 12,100	$ 0	$ 0

Basis of Presentation and Conso

Basis of Presentation and Consolidation	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Consolidation	BASIS OF PRESENTATION AND CONSOLIDATION Basis of Presentation The accompanying consolidated financial statements include the accounts of Blue Hills Bancorp, Inc. (the “Company”), a Maryland corporation, and its wholly-owned subsidiaries, Blue Hills Funding Corporation and Blue Hills Bank ("the Bank"), the principal operating entity. The Bank's wholly-owned subsidiaries include B.H. Security Corporation, HP Security Corporation, and 1196 Corporation, which are Massachusetts security corporations. All significant intercompany balances and transactions have been eliminated in consolidation. Business The Company provides a variety of financial services to individuals and businesses online and through its branches and loan offices in Boston, Cambridge, Concord, Dedham, Dorcheseter, Franklin, Hingham, Hyde Park, Lowell, Milton, Nantucket, Norwood, Marblehead, Plymouth, West Roxbury, Westwood, and Winchester Massachusetts. Its primary deposit products are checking, savings, money market and term certificate accounts and its primary lending products are residential mortgage loans, home equity loans, commercial real estate loans, commercial business loans and consumer loans. Use of estimates In preparing consolidated financial statements in conformity with accounting principles generally accepted in the United States of America, management is required to make estimates and assumptions that affect the reported amounts of assets and liabilities as of the date of the balance sheet and reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Material estimates that are particularly susceptible to significant change in the near term relate to the determination of the allowance for loan losses and the realizability of deferred tax assets. Cash and cash equivalents For purposes of the consolidated statements of cash flows, cash and cash equivalents include cash on hand, balances due from banks, and short-term investments comprised of federal funds sold, money-market mutual funds, and interest-bearing deposits, all of which mature within ninety days. The Company maintains balances on deposit with other financial institutions in excess of the federally insured limit. Restrictions on cash and due from banks The Company may be required to maintain average balances on hand or with the Federal Reserve Bank ( the “FRB”). At December 31, 2017 and December 31, 2016 there was no reserve requirement. Fair value hierarchy The Company groups its assets and liabilities measured at fair value in three levels, based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. Level 1 - Valuation is based on quoted prices in active markets for identical assets or liabilities. Valuations are obtained from readily available pricing sources for market transactions involving identical assets or liabilities. Level 2 - Valuation is based on observable inputs other than Level 1 prices, such as quoted prices for similar assets and liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets and liabilities. Level 3 - Valuation is based on unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Level 3 assets and liabilities include those whose value is determined using unobservable inputs to pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation. Securities Debt securities that management has the positive intent and ability to hold to maturity are classified as “held-to-maturity” and recorded at amortized cost. Securities not classified as held-to-maturity, including equity securities with readily determinable fair values, are classified as “available-for-sale” and recorded at fair value, with unrealized gains and losses excluded from earnings and reported in other comprehensive income. Purchase premiums and discounts are recognized in interest income using the interest method over the terms of the securities. Gains and losses on the sale of securities are recorded on the trade date and are determined using the specific identification method. At least quarterly, and more frequently when warranted by economic or market conditions, management evaluates all securities with a decline in fair value below the amortized cost of the investment to determine whether or not the impairment is deemed to be other-than-temporary ("OTTI"). OTTI is required to be recognized if: (1) the Company intends to sell the security; (2) it is more likely than not that the Company will be required to sell the security before recovery of its amortized cost basis; or (3) for debt securities, the present value of expected cash flows is not sufficient to recover the entire amortized cost basis. For all impaired debt securities that the Company intends to sell, or more likely than not will be required to sell, the full amount of the depreciation is recognized as OTTI through earnings. Credit-related OTTI for all other impaired debt securities is recognized through earnings. Non-credit related OTTI for such debt securities is recognized in other comprehensive income, net of applicable taxes. Marketable equity securities are evaluated for OTTI based on the severity and duration of the impairment and, if deemed to be other than temporary, the declines in fair value are reflected in earnings as realized losses. Federal Home Loan Bank stock The Company, as a member of the Federal Home Loan Bank of Boston (the "FHLBB") system, is required to maintain an investment in capital stock of the FHLBB. Based on the redemption provisions of the FHLBB, the stock has no quoted market value and is carried at cost. At its discretion, the FHLBB may declare dividends on the stock. The Company reviews its investment for impairment based on the ultimate recoverability of the cost basis in the FHLBB stock. As of December 31, 2017 , and 2016 , no impairment has been recognized. Loans held for sale Loans originated and intended for sale in the secondary market are carried at the lower of cost or estimated fair value in the aggregate. Net unrealized losses, if any, are recognized through a valuation allowance by charges to income. Loans The Company has historically granted mortgage and consumer loans to its customers and a substantial portion of the loan portfolio consists of mortgage loans in communities including and near the locations of its banking offices. The ability of the Company’s debtors to honor their contracts is dependent upon the real estate and general economic conditions in these areas. The Company’s loan portfolio includes 1-4 family residential real estate, home equity, commercial real estate, construction, commercial business, and consumer segments. Loans that management has the intent and ability to hold for the foreseeable future or until maturity or pay-off generally are reported at their outstanding unpaid principal balances adjusted for the allowance for loan losses, charge-offs, deferred origination fees and costs, and discounts and fair value adjustments on purchased loans. Interest income is accrued on the unpaid principal balance. Deferred loan origination fees/costs and discounts on purchased loans are recognized as an adjustment of the related loan yield using the interest method. It is the policy of the Company to discontinue the accrual of interest on loans past due in excess of 90 days, unless the loan is well-secured and in the process of collection, or when in the judgment of management, the ultimate collectability of the principal or interest becomes doubtful and to reverse all interest previously accrued against interest income. Past due status is based on contractual terms of the loan. The interest on non-accrual loans is accounted for on the cash-basis until qualifying for return to accrual. Loans are returned to accrual status when all the principal and interest amounts contractually due have been current for six consecutive months and future payments are reasonably assured. Allowance for loan losses The allowance for loan losses is based on the size and the composition of the loan portfolio, delinquency levels, loss experience, economic conditions and other factors related to the collectability of the loan portfolio. Prior to the second quarter of 2016, for portfolios for which the Company had insufficient loss experience, losses from a national peer group of depository institutions with assets between one and five billion dollars for relevant portfolios dating back to 2009 were used. Commencing in the second quarter of 2016, the Company began to phase in its own loss history by loan type based upon the age and loss experience of the loan portfolio. This change impacted the loss factors used for the majority of loan portfolios. Loss experience is updated at least quarterly with consideration given to unique circumstances in the portfolio. Loan losses are charged against the allowance when management believes the uncollectability of a loan balance is confirmed. Subsequent recoveries, if any, are credited to the allowance. The allowance for loan losses is evaluated regularly by management and reflects consideration of all significant factors that affect the collectability of the loan portfolio. The evaluation is inherently subjective as it requires estimates that are susceptible to significant revision as more information becomes available. It is the intention of management to maintain an allowance that is prudently commensurate with the growth and risk in the loan portfolio. The allowance consists of general, allocated and unallocated components, as further described below: General component The general component of the allowance for loan losses is based on a combination of the Company's own history and an extrapolated historical loss experience based on FDIC data for depository institutions with assets of one billion to five billion dollars dating back to 2009, adjusted for qualitative and environmental factors including changes to lending policies and procedures, economic and business conditions, portfolio characteristics, staff experience, problem loan trends, collateral values, concentrations and the competitive, legal and regulatory environment. The qualitative factors are determined based on the various risk characteristics of each loan segment. Risk characteristics relevant to each portfolio segment are as follows: Residential real estate - The Company does not generally originate loans with a loan-to-value ratio greater than 80 percent and does not generally grant loans that would be classified as subprime upon origination. When the Company does extend credit either on a first- or second-lien basis at a loan-to-value ratio greater than 80 percent , such loans are supported by either mortgage insurance or state guarantee programs. All loans in this segment are collateralized by owner-occupied, 1-4 family residential real estate and repayment is dependent on the credit quality of the individual borrower. The health of the national economy, including unemployment rates and housing prices, will have an effect on the credit quality of loans in this segment. Home equity - Loans in this segment are generally secured by first or second liens on residential real estate. Repayment is dependent on the credit quality of the individual borrower. The Company evaluates each loan application based on factors including the borrower’s credit score, income, length of employment, and other factors to establish the creditworthiness of the borrower. Commercial real estate - Loans in this segment include investment real estate and are generally secured by assignments of leases, real estate collateral and owner-occupied properties. In cases where there is a concentration of exposure to a single large tenant, underwriting standards include analysis of the tenant’s ability to support lease payments over the duration of the loan. The underlying cash flows generated by the properties may be adversely impacted by a downturn in the economy due to increased vacancy rates, which in turn, can have an effect on the credit quality in this segment. Payments on loans secured by income-producing properties often depend on the successful operation and management of the properties. Management continually monitors the cash flows of these loans. Construction - Loans in this segment primarily include real estate development loans for which payment is derived from permanent financing or sale of the property. Credit risk is affected by cost overruns, time to sell at an adequate price, and market conditions. Commercial business - Loans in this segment are generally secured by business assets, including accounts receivable, inventory, real estate and intangible assets. Strict underwriting standards include considerations of the borrower’s ability to support the debt service requirements from the underlying historical and projected cash flows of the business, collateral values, the borrower’s credit history and the ultimate collectability of the debt. Economic conditions, real estate values, commodity prices, unemployment trends and other factors will affect the credit quality of loans in these segments. Consumer - Loans in this segment primarily include used classic and collector automobile loans. A significant portion of the used automobile loan portfolio is comprised of geographically diverse loans originated by and purchased from a third party, who also provides collection services. Allocated component The allocated component relates to loans that are on the watch list (partially charged-off loans, non-accruing loans and accruing adversely-rated loans) and considered impaired. Impairment is measured by either 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. An allowance is established when the discounted cash flows (or collateral value) of the impaired loan is lower than the carrying value of that loan. A loan is considered impaired when, based on current information and events, it is probable that the Company will be unable to collect the scheduled payments of principal or interest when due according to the contractual terms of the loan agreement. Management reviews all loan types for individual impairment. Factors considered by management in determining impairment include payment status, collateral value, and the probability of collecting scheduled principal and interest payments when due. Loans that experience insignificant payment delays and payment shortfalls generally are not classified as impaired. Management determines the significance of payment delays and payment shortfalls on a case-by-case basis, taking into consideration all of the circumstances surrounding the loan and the borrower, including the length of the delay, the reasons for the delay, the borrower’s prior payment record, and the amount of the shortfall in relation to the principal and interest owed. The Company periodically may agree to modify the contractual terms of loans. When a loan is modified and a concession is made to a borrower experiencing financial difficulty, the modification is considered a troubled debt restructuring (“TDR”). All TDRs are initially classified as impaired and generally remain impaired for the remaining life of the loan. The impaired classification may be removed if the borrower demonstrates compliance with the modified terms and the restructuring agreement specifies an interest rate equal to that which would be provided to a borrower with similar credit at the time of restructuring. Unallocated component Through the third quarter of 2016, the Company maintained an unallocated component to cover uncertainties that could affect management’s estimate of probable losses. The unallocated component of the allowance reflected the margin of imprecision inherent in the underlying assumptions used in the methodologies for estimating allocated and general reserves in the portfolio. As a large portion of the Company's loan portfolio had seasoned, the unallocated component of the allowance for loan losses was eliminated during the fourth quarter of 2016. Foreclosed Assets Assets acquired through, or in lieu of, loan foreclosure are held for sale and are initially recorded at fair value, less cost to sell, at the date of foreclosure, establishing a new cost basis. Subsequent to foreclosure, valuations are periodically performed by management and the assets are carried at the lower of carrying amount or fair value less cost to sell. Revenue and expenses from operations, changes in the valuation allowance and any direct writedowns are included in net expenses from foreclosed assets. Premises and equipment Land is carried at cost. Buildings, leasehold improvements and equipment are stated at cost, less accumulated depreciation and amortization, computed on the straight-line method over the estimated useful lives of the assets or the expected terms of the leases, if shorter. Expected terms include lease option periods to the extent that the exercise of such options is reasonably assured. Goodwill and identifiable intangible assets Goodwill is the price paid in excess of the fair value of net assets acquired and is not amortized. Goodwill at December 31, 2017 and 2016 relates to the acquisition of Nantucket Bank. Goodwill is evaluated for impairment at least annually, or more often if warranted, using a combined qualitative and quantitative impairment approach.The initial qualitative approach assesses whether the existence of events or circumstances led to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If, after assessing the totality of events and circumstances, the Company determines it is more likely than not that the fair value is less than carrying value, the two-step quantitative impairment test is performed. Step one of the quantitative impairment test compares book value to the fair value of the reporting unit. If test one is failed, a more detailed analysis is performed, which involves measuring the excess of the fair value of the reporting unit, as determined in step one, over the aggregate fair value of the individual assets, liabilities, and identifiable intangibles as if the reporting unit was being acquired in a business combination. Effective January 1, 2017, the Company adopted Financial Accounting Standards Board ("FASB") Accounting Standards Update ("ASU") 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment. The amendments in this Update simplify the goodwill impairment model by eliminating the second step of the model. The resulting impairment test compares the fair value of a reporting unit with its carrying amount, including goodwill. If the carrying amount exceeds the reporting unit’s fair value, an impairment charge would be recognized for the difference, but should not exceed the carrying amount of goodwill allocated to that reporting unit. The Company still has the option to perform the qualitative assessment to determine if the quantitative impairment test is necessary. Early adoption of this Update had no impact on the Company’s consolidated financial statements. Identifiable intangible assets subject to amortization consist of the core deposit intangible acquired in the acquisition of Nantucket Bank, which has an estimated life of approximately 5.5 years. Identifiable intangible assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable. The core deposit intangible is being amortized using the sum of the years' digits method over its estimated life. Information related to the core deposit intangible, including the estimated annual amortization expense, is summarized below: (In thousands) Balance at December 31, 2014 $ 4,232 Amortization (1,607 ) Balance at December 31, 2015 2,625 Amortization (1,225 ) Balance at December 31, 2016 1,400 Amortization (843 ) Balance at December 31, 2017 $ 557 Estimated amortization expense for the years ending December 31, 2018 $ 461 2019 96 Total remaining $ 557 Bank-owned life insurance Bank-owned life insurance policies are reflected on the consolidated balance sheets at cash surrender value. Changes in cash surrender value are reflected in noninterest income in the consolidated statements of net income. Mortgage Servicing Rights The Company services mortgage loans for others. Mortgage servicing assets are recognized as separate assets when rights are acquired through purchase or through sale of financial assets. Fair value is determined using prices for similar assets with similar characteristics, when available, or based upon discounted cash flows using market-based assumptions. The valuation model incorporates assumptions that market participants would use in estimating future net servicing income, such as the cost to service, the discount rate, an inflation rate, ancillary income, prepayment speeds and default rates and losses. Capitalized servicing rights are reported in other assets and are amortized into loan servicing fee income in proportion to, and over the period of, the estimated future net servicing income of the underlying financial assets. Servicing assets are evaluated for impairment based upon the fair value of the rights as compared to amortized cost. Impairment is determined by stratifying rights by predominant risk characteristics, such as interest rates and terms. Impairment is recognized through a valuation allowance for an individual stratum, to the extent that fair value is less than the capitalized amount for the stratum. Changes in the valuation allowance are reported in loan servicing fee income. Non-marketable investments The aggregate carrying amount of all cost and equity method investments included in other assets at December 31, 2017 and 2016 is $ 11.3 million and $ 10.2 million , respectively. The fair values of these investments are not readily available and are not evaluated for impairment unless there are identified events or changes in circumstances that may have a significant adverse effect on the fair value of the investments. At December 31, 2017 and 2016 , the Company was contractually committed under these non-marketable investments to make additional capital contributions of $9.4 million and $8.9 million , respectively. Interest rate swap agreements For asset/liability management purposes, the Company periodically uses interest rate swap agreements to hedge various exposures or to modify interest rate characteristics of various balance sheet accounts. All interest rate swap agreements are recorded at fair value. Depending upon the intended use for the interest rate swap 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. If the interest rate swap is not designated in a hedge relationship, gains or losses reflecting changes in fair value are recorded in earnings. Certain interest rate swap contracts are utilized to help commercial loan borrowers manage their interest rate risk. The interest rate swap contracts with commercial loan borrowers allow the borrowers to convert floating rate loan payments to fixed rate payments. When the Company enters into an interest rate swap contract with a commercial loan borrower, the Company concurrently enters into a matching interest rate swap with a correspondent bank counterparty in order to minimize interest rate risk to the Company. These interest rate derivative instruments are recorded on the consolidated balance sheets as either an asset or liability measured at fair value. These derivatives do not qualify for hedge accounting. As such, all changes in fair value of these derivative instruments are included in miscellaneous income. The Company pays and receives fees for entering into these contracts. The net fees are recognized in loan level derivative income when received. Derivative Loan Commitments Mortgage loan commitments are referred to as derivative loan commitments if the loan that will result from exercise of the commitment will be held for sale upon funding. Loan commitments that are derivatives are recognized at fair value on the consolidated balance sheet in other assets and other liabilities with changes in their fair values recorded in mortgage banking income. Forward Loan Sale Commitments To protect against the price risk inherent in derivative loan commitments, the Company enters into forward loan sale commitments to mitigate the risk of potential decreases in the values of loans that would result from the exercise of the derivative loan commitments. Forward loan sale commitments are recognized at fair value on the consolidated balance sheet in other assets or other liabilities with changes in their fair values recorded in mortgage banking income. The Company estimates the fair value of its forward loan sale commitments based on changes in the fair value of underlying mortgage loans. Transfers of financial assets Transfers of an entire financial asset, a group of entire financial assets, or a participating interest in an entire financial asset 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. During the normal course of business, the Company may transfer a portion of a financial asset, for example, a participation loan. In order to be eligible for sales treatment, the transfered portion of the loan must meet the criteria of a participating interest. If it does not meet the criteria of a participating interest, the transfer must be accounted for as a secured borrowing. In order to meet the criteria for a participating interest, all cash flows from the loan must be divided proportionately, the rights of each loan holder must have the same priority, the loan holders must have no recourse to the transferor other than standard representations and warranties and no loan holder has the right to pledge or exchange the entire loan. Retirement plan The Company accounts for its defined benefit pension plan using an actuarial model that allocates pension costs over the service period of employees in the plan. The Company accounts for the over-funded or under-funded status of its defined benefit plan as an asset or liability on its consolidated balance sheets and recognizes changes in the funded status that are not reflected in net periodic pension cost as other comprehensive income or loss. The Company amended its defined benefit pension plan in 2013 freezing the plan to new participants and subsequently amended the plan and froze it for all participants effective October 31, 2014. Earnings per common share Basic earnings per share represents income available to common stockholders divided by the weighted-average number of common shares outstanding during the period. Unallocated ESOP shares are not deemed outstanding for earnings per share calculations. Dividend rights on unvested restricted stock awards are forfeitable; therefore unvested restricted stock awards are not considered outstanding in the computation of basic earnings per share. Diluted earnings per share reflects additional common shares that would have been outstanding if dilutive potential common shares had been issued, as well as any adjustment to income that would result from the assumed issuance. Potential common shares that may be issued by the Company relate to outstanding stock options and unvested restricted stock awards and are determined using the treasury stock method. Advertising costs Advertising costs are expensed as incurred. Share-based Compensation Plans The Company measures and recognizes compensation cost relating to share-based payment transactions based on the grant-date fair value of the equity instruments issued. Share-based compensation is recognized over the period the employee is required to provide services for the award. The Company uses the Black-Scholes option-pricing model to determine the fair value of stock options granted. For an award with a performance and/or service condition that affects vesting, the performance and/or service condition is not considered in determining the award’s fair value on the grant date. On January 1, 2017, the Company applied the changes related to FASB ASU 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. Under this Update, the Company has elected to account for forfeitures of share-based payments by recognizing forfeitures of awards as they occur (e.g., when an award does not vest because the employee leaves the Company or does not meet specific performance measures). The transition to this methodology is applied on a modified retrospective basis, whereby the compensation cost is calculated as if the company did not historically record a forfeiture estimate for outstanding awards and instead accounted for forfeitures of outstanding awards as the forfeitures occurred, with a cumulative-effect adjustment to retained earnings. The cumulative effect of changing to this methodology resulted in a $27,000 adjustment to beginning retained earnings in the consolidated statement of changes in stockholders' equity for the year ended December 31, 2017 . Employee Stock Ownership Plan Compensation expense for the 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 period. 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. Unearned compensation applicable to the ESOP is reflected as a reduction of stockholders' equity on the consolidated balance sheet. 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. Income taxes Deferred tax assets and liabilities are reflected at currently enacted income tax rates applicable to the period in which the deferred tax assets or liabilities are expected to be realized or settled. As changes in tax laws or rates are enacted, deferred tax assets and liabilities are adjusted through the provision for income taxes. A ccordingly, changes resulting from the Tax Cuts and Jobs Act enacted on December 22, 2017 have been recognized in the consolidated financial statements as of and for the year ended December 31, 2017. See Note 8. The Company exercises significant judgment in evaluating the amount and timing of recognition of the resulting tax assets and liabilities. These judgments require the Company to make projections of future taxable income. These judgments and estimates, which are inherently subjective, are reviewed periodically as regulatory and business factors change. A valuation allowance related to deferred tax assets is established when, in the judgment of management, it is more likely than not that all or a portion of such deferred tax assets will not be realized. A tax position that meets the more likely than not recognition threshold is initially and subsequently measured as the largest amount of tax benefit that has a greater than 50% likelihood of being realized upon settlement with a taxing authority that has full knowledge of all relevant information. The determination of whether or not a tax position has met the more likely than not recognition threshold considers the facts, circumstances and information available at the reporting date and is subject to management’s judgment. There was no reserve for uncertain tax positions as of December 31, 2017 or 2016 . The Company records interest and penalties as part of income tax expense. Effective January 1, 2017, with the application of ASU 2016-09, Compensation

Recent Accounting Standards Upd

Recent Accounting Standards Updates	12 Months Ended
	Dec. 31, 2017
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Standards Updates	RECENT ACCOUNTING STANDARDS UPDATES In February 2018, the FASB issued ASU 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. The purpose of this Update is to allow a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. The Update is effective for public business entities for annual periods being after December 15, 2018, and interim periods within those fiscal years. Early adoption of the amendments in this Update is permitted, including adoption in any interim period. The Company adopted the Update on January 1, 2018. The impact to the consolidated financial statements upon adopting this Update is not material. See Note 16 to the consolidated financial statements. In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging:Targeted Improvements to Accounting for Hedging Activities . The purpose of this Update is to better align a company’s financial reporting for hedging activities with the economic objectives of those activities. This Update is effective for public business entities for fiscal years beginning after December 15, 2018, with early adoption, including adoption in an interim period permitted. The Update requires a modified retrospective transition method in which the Company will recognize the cumulative effect of the change on the opening balance of each affected component of equity in the statement of financial position as of the date of adoption. While the Company continues to assess all potential impacts of the standard, we currently expect the adoption to have an immaterial impact on our consolidated financial statements. In May 2017, the FASB issued ASU 2017-09, Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting which amends the scope of modification accounting for share-based payment arrangements. The Update provides guidance on the types of changes to the terms or conditions of share-based payment awards to which an entity would be required to apply modification accounting. Specifically, an entity would not apply modification accounting if the fair value, vesting conditions, and classification of the awards are the same immediately before and after the modification. The Update is effective for public business entities for annual periods being after December 15, 2017, including interim periods within those annual periods. The Update should be applied prospectively to awards modified on or after the effective date. The impact to the consolidated financial statements upon adopting this Update is not expected to be material. In January 2016, the FASB issued ASU 2016-01, Financial Instruments – Overall, (Subtopic 825-10) . The amendments in this Update address certain aspects of recognition, measurement, presentation, and disclosure of financial instruments. Targeted improvements to generally accepted accounting principles include the requirement for equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income and the elimination of the requirement for public business entities to disclose the methods and significant assumptions used to estimate the fair value for financial instruments measured at amortized cost. For public business entities, the amendments in this Update are effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The Company does not anticipate that adoption of the Update will materially impact the Company's financial position. The Update also requires Companies to utilize an "exit price" fair value methodology when measuring the fair value of financial instruments. The impact of the change, if applied, to the Company's equity investments for the year ended December 31, 2017 would have resulted in a gain of $1.7 million (pre-tax) being recognized in net income, after reclassification for the realized loss on mutual funds. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) . This Update is intended to improve financial reporting about leasing transactions and the key provision impacting the Company is the requirement for a lessee to record a right-to-use asset and a liability representing the obligation to make lease payments for long-term operating leases. Additionally, the Update includes additional quantitative and qualitative disclosures required by lessees and lessors to help users better understand the amount, timing, and uncertainty of cash flows arising from leases. This Update is effective for fiscal years beginning after December 31, 2018, and interim periods within those fiscal years. Lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The modified retrospective approach includes a number of optional practical expedients that entities may elect to apply as well as transition guidance specific to nonstandard leasing transactions. The Company's assets and liabilities will increase based on the present value of remaining lease payments for leases in place at the adoption date; however, this is not expected to be material to the Company's results of operations or financial position. Future lease commitments as of December 31, 2017 amounted to $21.8 million . In June, 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , which removes the thresholds that companies apply to measure credit losses on financial instruments measured at amortized cost, such as loans, receivables, and held-to-maturity debt securities. Under current U.S. GAAP, companies generally recognize credit losses when it is probable that the loss has been incurred. The revised guidance will remove previously established recognition thresholds based on probability, and will require companies to recognize an allowance for credit losses for the difference between the amortized cost basis of a financial instrument and the net amount that the company expects to collect over the instrument’s contractual life. ASU 2016-13 also amends the credit loss measurement guidance for available-for-sale debt securities and will require that credit losses be recorded through an allowance for credit losses. Additionally, this Update may reduce the carrying value of the Company's held-to-maturity investment securities as it will require an allowance on the expected losses over the life of these securities to be recorded upon adoption. The ASU is effective for public business entities fiscal years beginning after December 15, 2019 and for interim periods within those fiscal years. Any increase in our allowance for loan losses or expenses may have a material adverse effect on our financial condition and results of operations. The Company is actively working through the provisions of the Update. Management has established a steering committee which has identified the methodologies and the additional data requirements necessary to implement the Update and has engaged a third-party software service provider to assist in the Company's implementation. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers . This Update 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. This Update is effective for annual periods beginning after December 15, 2017, including interim periods within that reporting period with early adoption permitted. The Company's revenue relates principally to financial instruments, which are explicitly excluded from the scope of the new guidance. Therefore the impact to the consolidated financial statements upon adopting this Update is not expected to be material. In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory . The amendments in this Update require an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. For public business entities, the amendments are effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within those annual reporting periods. The impact to the consolidated financial statements upon adopting this Update is not expected to be material. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash . The amendments in this Update require that in the statement of cash flows, amounts generally described as restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts. For public business entities, the amendments are effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The impact to the consolidated financial statements upon adopting this Update is not expected to be material.

Securities

Securities	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Securities	SECURITIES The amortized cost and estimated fair value of securities available for sale and held to maturity, with gross unrealized gains and losses, follow: December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (In thousands) Securities Available for Sale: Marketable equity securities $ 9,437 $ 755 $ (472 ) $ 9,720 Securities Held to Maturity: Debt securities: Government-sponsored enterprises $ 30,673 $ — $ (894 ) $ 29,779 Government-sponsored mortgage-backed and collateralized mortgage obligations 244,668 30 (3,437 ) 241,261 SBA asset-backed securities 28,375 28 (329 ) 28,074 Total securities held to maturity $ 303,716 $ 58 $ (4,660 ) $ 299,114 December 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (In thousands) Securities Available for Sale: Debt securities: Mortgage- and other asset-backed securities: Privately issued commercial mortgage-backed securities $ 10,530 $ — $ (41 ) $ 10,489 Other asset-backed securities 9,174 6 (195 ) 8,985 Total mortgage- and other asset-backed securities 19,704 6 (236 ) 19,474 State and political 12,730 120 (157 ) 12,693 Financial services: Banks 20,263 57 (298 ) 20,022 Diversified financial entities 17,198 190 (198 ) 17,190 Insurance and REITs 18,304 150 (216 ) 18,238 Total financial services 55,765 397 (712 ) 55,450 Other corporate: Industrials 49,217 508 (761 ) 48,964 Utilities 24,895 292 (100 ) 25,087 Total other corporate 74,112 800 (861 ) 74,051 Total debt securities 162,311 1,323 (1,966 ) 161,668 Marketable equity securities: Mutual funds: Domestic community 3,216 25 (19 ) 3,222 Global asset allocation 42,396 48 (2,498 ) 39,946 Total marketable equity securities 45,612 73 (2,517 ) 43,168 Total securities available for sale $ 207,923 $ 1,396 $ (4,483 ) $ 204,836 Securities Held to Maturity: Debt securities: Government-sponsored enterprises $ 32,667 $ 4 $ (934 ) $ 31,737 Government-sponsored mortgage-backed and collateralized mortgage obligations 153,938 14 (1,806 ) 152,146 SBA asset-backed securities 14,422 — (212 ) 14,210 Total securities held to maturity $ 201,027 $ 18 $ (2,952 ) $ 198,093 During the third quarter of 2015, approximately $196.3 million of securities available for sale, with net unrealized gains of $666,000 , were reclassified to held-to-maturity designation. Held-to-maturity investments are investments that management has the positive intent and ability to hold to maturity. If a security is reclassified from available-for-sale to held-to-maturity, the fair value at the time of transfer becomes the security's new cost basis. The unrealized holding gain at the transfer date continues to be reported in accumulated other comprehensive income and is amortized over the security's remaining life as an adjustment of yield in a manner similar to a premium or discount. At December 31, 2017 , there are $250,000 of net holding gains remaining in accumulated other comprehensive income. The amortized cost and estimated fair value of debt securities by contractual maturity at December 31, 2017 follow. Expected maturities will differ from contractual maturities because the issuers may have the right to call or prepay obligations with or without call or prepayment penalties. Based on expected maturities, the mortgage and asset-backed securities and collateralized mortgage obligations, included below, have a 3.9 year weighted average duration. Held to Maturity Amortized Cost Fair Value (In thousands) After 1 year through 5 years $ 15,626 $ 15,366 After 5 years through 10 years 15,047 14,413 30,673 29,779 Mortgage- and asset-backed securities and collateralized mortgage obligations amortizing monthly 273,043 269,335 Total debt securities $ 303,716 $ 299,114 For the years ended December 31, 2017 , 2016 and 2015 , proceeds from sales of securities available for sale amounted to $213.1 million , $97.8 million and $99.5 million , respectively. Gross realized gains amounted to $2.2 million , $2.3 million and $2.0 million , respectively, and gross realized losses amounted to $2.3 million , $981,000 and $56,000 , respectively. At December 31, 2017 and 2016 , government-sponsored enterprise obligations with an amortized cost of $30.7 million and $27.3 million , respectively, and a fair value of $30.3 million and $27.0 million , respectively, were pledged to secure borrowings. See Note 7. The Company continually reviews investment securities for the existence of OTTI, taking into consideration current market conditions, the extent and nature of changes in fair value, issuer rating changes and trends, the credit worthiness of the obligor of the security, volatility of earnings, current analysts’ evaluations, the Company’s intent to sell the security, or whether it is more likely than not that the Company will be required to sell the debt security before its anticipated recovery, as well as other qualitative factors. The term “other-than-temporary” is not intended to indicate that the decline is permanent, but indicates that the prospects for a near-term recovery of value is not necessarily favorable, or that there is a lack of evidence to support a realizable value equal to or greater than the carrying value of the investment. Information pertaining to securities with gross unrealized losses aggregated by investment category and length of time that individual securities have been in a continuous loss position, follows: December 31, 2017 Less Than Twelve Months More Than Twelve Months Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value (In thousands) Securities Available for Sale: Temporarily impaired marketable equity securities $ (449 ) $ 4,310 $ (23 ) $ 443 Securities Held to Maturity: Debt securities: Government-sponsored enterprises $ (109 ) $ 8,521 $ (785 ) $ 21,258 Government-sponsored mortgage-backed and collateralized mortgage obligations (1,563 ) 119,782 (1,874 ) 111,712 SBA asset-backed securities (34 ) 9,897 (295 ) 11,423 Total temporarily impaired securities held to maturity $ (1,706 ) $ 138,200 $ (2,954 ) $ 144,393 December 31, 2016 Less Than Twelve Months More Than Twelve Months Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value (In thousands) Securities Available for Sale: Debt securities: Mortgage- and other asset-backed securities: Privately issued commercial mortgage- backed securities $ (11 ) $ 3,163 $ (30 ) $ 7,326 Other asset-backed securities (43 ) 3,924 (152 ) 3,732 Total mortgage- and other asset-backed securities (54 ) 7,087 (182 ) 11,058 State and political (157 ) 5,301 — — Financial services: Banks (298 ) 14,553 — — Diversified financial entities (198 ) 9,369 — — Insurance and REITs (216 ) 6,900 — — Total financial services (712 ) 30,822 — — Other corporate: Industrials (655 ) 24,630 (106 ) 2,284 Utilities (99 ) 11,200 (1 ) 794 Total other corporate (754 ) 35,830 (107 ) 3,078 Total debt securities (1,677 ) 79,040 (289 ) 14,136 Marketable equity securities: Mutual funds: Domestic community — — (19 ) 448 Global asset allocation (424 ) 15,153 (2,074 ) 22,442 Total marketable equity securities (424 ) 15,153 (2,093 ) 22,890 Total temporarily impaired securities available for sale $ (2,101 ) $ 94,193 $ (2,382 ) $ 37,026 Securities Held to Maturity: Debt securities: Government-sponsored enterprises $ (934 ) $ 28,533 $ — $ — Government-sponsored mortgage-backed and collateralized mortgage obligations (1,763 ) 146,098 (43 ) 3,827 SBA asset-backed securities (104 ) 9,157 (108 ) 5,053 Total temporarily impaired securities held to maturity $ (2,801 ) $ 183,788 $ (151 ) $ 8,880 At December 31, 2017 , several debt securities have unrealized losses with aggregate depreciation of less than 2% from the Company’s amortized cost basis. The unrealized losses were primarily caused by interest rate fluctuations. It is expected that none of these securities would be settled at a price less than the par value of the investment. Because the decline in market value is attributable to changes in interest rates and not to credit quality, and because the Company does not intend to sell the securities and it is more likely than not that the Company will not be required to sell the securities before recovery of their amortized cost bases, which may be maturity, the Company does not consider these securities to be other than temporarily impaired at December 31, 2017 . At December 31, 2017 , three equity securities have aggregate unrealized losses of $472,000 ; 9% of the Company’s cost basis. No issues have been identified that cause management to believe the declines in market value are other than temporary and the Company has the ability and intent to hold these investments until a recovery of fair value.

Loans and The Allowance for Loa

Loans and The Allowance for Loan Losses	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Loans and The Allowance for Loan Losses	LOANS AND THE ALLOWANCE FOR LOAN LOSSES A summary of the balances of loans follows: December 31, 2017 2016 (In thousands) Real estate: 1-4 family residential $ 922,627 $ 851,154 Home equity 80,662 78,719 Commercial real estate 834,264 687,289 Construction 91,050 76,351 1,928,603 1,693,513 Commercial business 253,509 206,234 Consumer 21,698 29,281 Total loans 2,203,810 1,929,028 Allowance for loan losses (20,877 ) (18,750 ) Discount and fair value adjustments on purchased loans (1,477 ) (1,846 ) Deferred loan costs and fees, net 4,691 4,439 Loans, net $ 2,186,147 $ 1,912,871 The Company has sold residential mortgage loans in the secondary mortgage market, some of which are sold with limited recourse. The Company has retained the servicing responsibility on a portion of the loans sold and receives fees for the services provided. The unpaid principal balances of mortgage loans serviced for others were $245.1 million and $89.7 million at December 31, 2017 and 2016 , respectively. The maximum contingent liability associated with loans sold with recourse is $7.6 million at December 31, 2017 . Neither mortgage loans serviced for others nor the contingent liability associated with sold loans is recorded on the consolidated balance sheets. There have been no contingency losses recognized on these loans to date. The Company has transferred a portion of its originated commercial real estate, commercial business and construction loans to participating lenders. The amounts transferred have been accounted for as sales and are therefore not included on the consolidated balance sheets. The Company and participating lenders share ratably in cash flows and any gains or losses that may result from a borrower’s lack of compliance with contractual terms of the loan. The Company continues to service the loans on behalf of the participating lenders and, as such, collects cash payments from the borrowers, remits payments (net of servicing fees) to participating lenders and disburses required escrow funds to relevant parties. At December 31, 2017 and 2016 , the Company was servicing loans for participants aggregating $88.8 million and $56.0 million , respectively. At December 31, 2017 and 2016 , 1-4 family residential loans in the amount of $816.9 million and $759.9 million , respectively, and commercial real estate loans in the amount of $266.3 million and $293.1 million , respectively, were pledged to secure borrowings. See Note 7. Activity in the allowance for loan losses for the years ended December 31, 2017 , 2016 and 2015 follows: 1-4 Family Home Commercial Construction Commercial Consumer Unallocated Total (In thousands) 2017 Beginning balance $ 4,846 $ 537 $ 8,374 $ 1,353 $ 3,206 $ 434 $ — $ 18,750 Provision for loan losses 83 162 1,283 355 193 22 — 2,098 Loans charged-off (52 ) — (73 ) — — (134 ) — (259 ) Recoveries 199 — — — 74 15 — 288 Ending balance $ 5,076 $ 699 $ 9,584 $ 1,708 $ 3,473 $ 337 $ — $ 20,877 2016 Beginning balance $ 3,916 $ 636 $ 7,147 $ 1,364 $ 2,839 $ 772 $ 428 $ 17,102 Provision (credit) for loan losses 830 (99 ) 1,447 (11 ) 3,428 (282 ) (428 ) 4,885 Loans charged-off — — (321 ) — (3,098 ) (56 ) — (3,475 ) Recoveries 100 — 101 — 37 — — 238 Ending balance $ 4,846 $ 537 $ 8,374 $ 1,353 $ 3,206 $ 434 $ — $ 18,750 2015 Beginning balance $ 3,222 $ 340 $ 3,551 $ 1,056 $ 3,410 $ 736 $ 658 $ 12,973 Provision (credit) for loan losses 612 296 3,596 308 (571 ) 79 (230 ) 4,090 Loans charged-off — — — — — (43 ) — (43 ) Recoveries 82 — — — — — — 82 Ending balance $ 3,916 $ 636 $ 7,147 $ 1,364 $ 2,839 $ 772 $ 428 $ 17,102 Additional information pertaining to the allocation of the allowance for loan losses to loan segments at December 31, 2017 and 2016 , follows: 1-4 Family Home Commercial Construction Commercial Consumer Unallocated Total (In thousands) December 31, 2017 Allowance related to impaired loans $ 80 $ — $ — $ — $ — $ 1 $ — $ 81 Allowance related to non-impaired loans 4,996 699 9,584 1,708 3,473 336 — 20,796 Total allowance for loan losses $ 5,076 $ 699 $ 9,584 $ 1,708 $ 3,473 $ 337 $ — $ 20,877 Impaired loans $ 5,949 $ 1,387 $ 4,744 $ — $ — $ 202 $ — $ 12,282 Non-impaired loans 916,678 79,275 829,520 91,050 253,509 21,496 — 2,191,528 Total loans $ 922,627 $ 80,662 $ 834,264 $ 91,050 $ 253,509 $ 21,698 $ — $ 2,203,810 December 31, 2016 Allowance related to impaired loans $ 17 $ — $ — $ — $ — $ — $ — $ 17 Allowance related to non-impaired loans 4,829 537 8,374 1,353 3,206 434 — 18,733 Total allowance for loan losses $ 4,846 $ 537 $ 8,374 $ 1,353 $ 3,206 $ 434 $ — $ 18,750 Impaired loans $ 6,726 $ 1,153 $ 941 $ — $ 241 $ 170 $ — $ 9,231 Non-impaired loans 844,428 77,566 686,348 76,351 205,993 29,111 — 1,919,797 Total loans $ 851,154 $ 78,719 $ 687,289 $ 76,351 $ 206,234 $ 29,281 $ — $ 1,929,028 The following is a summary of past due and non-accrual loans, by loan segment, at December 31, 2017 and 2016 : 30-59 Days Past Due 60-89 Days Past Due Past Due 90 Days or More Total Past Due Loans on Non-accrual (In thousands) December 31, 2017 Real estate: 1-4 family residential $ 381 $ 348 $ 2,184 $ 2,913 $ 5,190 Home equity 509 13 656 1,178 1,387 Commercial real estate — — 3,893 3,893 4,744 Consumer 107 7 92 206 202 Total $ 997 $ 368 $ 6,825 $ 8,190 $ 11,523 December 31, 2016 Real estate: 1-4 family residential $ 584 $ 373 $ 2,322 $ 3,279 $ 6,478 Home equity 452 496 775 1,723 1,153 Commercial real estate 1,393 — — 1,393 941 Commercial business 4,996 13 — 5,009 241 Consumer 175 5 7 187 170 Total $ 7,600 $ 887 $ 3,104 $ 11,591 $ 8,983 There were no loans past due 90 days or more and still accruing at December 31, 2017 and 2016 . The following is a summary of information pertaining to impaired loans by loan segment at the dates indicated: Recorded Investment Unpaid Principal Balance Related Allowance December 31, 2017 (In thousands) Impaired loans without a valuation allowance: Real estate: 1-4 family residential $ 4,501 $ 4,897 $ — Home equity 1,387 1,523 — Commercial real estate 4,744 5,206 — Commercial business — 11 — Consumer 191 243 — Total 10,823 11,880 — Impaired loans with a valuation allowance: Real estate: 1-4 family residential 1,448 1,448 80 Consumer 11 11 1 Total 1,459 1,459 81 Total impaired loans $ 12,282 $ 13,339 $ 81 December 31, 2016 Impaired loans without a valuation allowance: Real estate: 1-4 family residential $ 6,605 $ 7,023 $ — Home equity 1,153 1,225 — Commercial real estate 941 1,207 — Commercial business 241 3,279 — Consumer 170 183 — Total 9,110 12,917 — Impaired loans with a valuation allowance: 1-4 family residential 121 313 17 Total impaired loans $ 9,231 $ 13,230 $ 17 The following tables set forth information regarding average balances and interest income recognized (the majority of which is on a cash basis) on impaired loans, by segment, for the years ended December 31, 2017 , 2016 and 2015 : Average Recorded Investment Interest Income Recognized 2017 (In thousands) Real estate: 1-4 family residential $ 6,254 $ 281 Home equity 1,264 58 Commercial real estate 4,125 220 Commercial business 129 20 Consumer 241 9 Total $ 12,013 $ 588 2016 Real estate: 1-4 family residential $ 6,451 $ 449 Home equity 555 29 Commercial real estate 3,192 206 Commercial business 672 55 Consumer 160 12 Total $ 11,030 $ 751 2015 Real estate: 1-4 family residential $ 4,869 $ 270 Home equity 575 14 Commercial real estate 926 161 Commercial business 2 1 Consumer 78 6 Total $ 6,450 $ 452 No additional funds are committed to be advanced in connection with impaired loans. Troubled debt restructurings recorded during the year ended December 31, 2017 totaled $973,000 . There were no material troubled debt restructurings recorded during the years ended December 31, 2016 and 2015. Credit Quality Information The Company utilizes a ten-grade internal loan rating system for all loans as follows: Loans rated 1 - 6 are considered "acceptable" rated loans that are performing as agreed, and generally require only routine supervision. Loans rated 7 are considered “special mention.” These loans are starting to show signs of potential weakness and are being closely monitored by management. Loans rated 8 are considered “substandard.” Generally, a loan is considered substandard if it is inadequately protected by the current net worth and paying capacity of the obligors and/or the collateral pledged. There is a distinct possibility that the Company will sustain some loss if the weakness is not corrected. Generally, all loans 90 days delinquent are rated 8. Loans rated 9 are considered “doubtful.” Serious problems exist to the point where a partial loss of principal is likely. Weakness is so pronounced that on the basis of current information, conditions and values, collection in full is highly improbable. Loans rated 10 are considered "loss" and the credit extended to the customer is considered uncollectible or of such little value that it does not warrant consideration as an active asset. The Company assigns a 6 risk-rating to otherwise performing, satisfactorily collateralized consumer and residential loans where the Company becomes aware of deterioration in a FICO score or other indication of potential inability to service the debt. The Company assigns risk ratings of 7-10 to residential or consumer loans that have a well-defined weakness that may jeopardize the collection of the contractual principal and interest, are contractually past due 90 days or more or legal action has commenced against the borrower. All other residential mortgage and consumer loans have no risk rating. On an annual basis, or more often if needed, the Company formally reviews the ratings on all commercial and construction loans. At least annually, the Company engages an independent third party to review a significant portion of loans within these segments. Management uses the results of these reviews as part of its annual review process. Management primarily utilizes delinquency reports, the watch list and other loan reports to monitor credit quality of other loan segments. The following tables present the Company’s loans by risk rating at December 31, 2017 and 2016 : 1-4 Family Residential Home Equity Commercial Real Estate Construction Commercial Business Consumer Total Loans (In thousands) December 31, 2017 Loans rated 1 - 6 $ 1,022 $ 270 $ 821,815 $ 91,050 $ 252,765 $ 3 $ 1,166,925 Loans rated 7 2,848 1,523 4,660 — 744 121 9,896 Loans rated 8 2,566 — 7,789 — — — 10,355 Loans rated 9 250 — — — — — 250 Loans rated 10 — — — — — — — Loans not rated 915,941 78,869 — — — 21,574 1,016,384 $ 922,627 $ 80,662 $ 834,264 $ 91,050 $ 253,509 $ 21,698 $ 2,203,810 December 31, 2016 Loans rated 1 - 6 $ 1,054 $ 293 $ 671,872 $ 76,351 $ 188,706 $ 4 $ 938,280 Loans rated 7 3,514 967 9,720 — 17,510 146 31,857 Loans rated 8 2,442 258 5,697 — 18 37 8,452 Loans rated 9 645 — — — — — 645 Loans rated 10 — — — — — — — Loans not rated 843,499 77,201 — — — 29,094 949,794 $ 851,154 $ 78,719 $ 687,289 $ 76,351 $ 206,234 $ 29,281 $ 1,929,028

Premises and Equipment

Premises and Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Premises and Equipment	PREMISES AND EQUIPMENT A summary of the cost and accumulated depreciation and amortization of premises and equipment follows: December 31, Estimated Useful Lives 2017 2016 (In thousands) Land $ 4,087 $ 4,087 Buildings 11,043 10,322 5 to 40 years Leasehold improvements 9,551 9,334 5 to 10 years Furniture and fixtures 4,139 3,874 3 to 5 years Technology equipment 6,579 6,139 1 to 3 years Construction in progress 185 169 Premises and equipment, gross 35,584 33,925 Less accumulated depreciation and amortization (14,011 ) (11,891 ) Premises and equipment, net $ 21,573 $ 22,034 Depreciation and amortization expense for the years ended December 31, 2017 , 2016 and 2015 amounted to $2.1 million , $2.0 million and $1.8 million , respectively.

Deposits

Deposits	12 Months Ended
	Dec. 31, 2017
Banking and Thrift [Abstract]
Deposits	DEPOSITS A summary of deposit balances, by type, is as follows: December 31, 2017 2016 (In thousands) NOW and demand $ 381,316 $ 331,508 Regular savings 221,004 262,984 Money market 646,603 573,204 Brokered money market 92,798 53,357 Total non-certificate accounts 1,341,721 1,221,053 Term certificates of $250,000 or more 134,649 77,550 Term certificates less than $250,000 313,733 262,564 Brokered certificates of deposit 249,766 247,520 Total certificate accounts 698,148 587,634 Total deposits $ 2,039,869 $ 1,808,687 At December 31, 2017 , the scheduled maturities of certificate accounts, including brokered certificates of deposits, are as follows: Amount Weighted Average Rate (Dollars in thousands) 2018 406,362 1.18 % 2019 180,672 1.72 2020 62,733 1.79 2021 19,513 1.84 2022 28,868 2.04 $ 698,148 1.43 %

Borrowings

Borrowings	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Borrowings	BORROWINGS Federal Home Loan Bank of Boston advances FHLBB advances with an original maturity of less than one year amounted to $100.0 million and $146.0 million at December 31, 2017 and 2016 , respectively, with a weighted average rate of 1.57% and 0.76% , respectively. The Company also had, at both December 31, 2017 and 2016 , a $7.7 million line of credit with the FHLBB with an interest rate that adjusts daily. No advances were outstanding on this line at December 31, 2017 or 2016 . All borrowings from the FHLBB are secured by a blanket security agreement on qualified collateral, principally residential and commercial mortgage loans, as well as certain U.S. government-sponsored enterprise securities. See Notes 3 and 4. Long-term debt consists of the following FHLBB advances: December 31, 2017 December 31, 2016 Amount Weighted Average Rate Amount Weighted Average Rate (Dollars in thousands) Fixed-rate advances maturing: 2017 $ — — % $ 15,000 1.99 % 2018 25,000 1.97 20,000 2.12 2019 35,000 1.32 25,000 1.20 2020 35,000 1.70 15,000 1.49 2021 — — 30,000 0.28 2022 * 10,000 0.42 — — $ 105,000 1.51 % $ 105,000 1.27 % * Includes advances callable in 2018 Other lines-of-credit At both December 31, 2017 and 2016 , the Company had $42.0 million in available unsecured federal funds lines with correspondent banks, which could be drawn upon, as needed. There were no amounts outstanding at December 31, 2017 or 2016 .

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES Allocation of federal and state income taxes between current and deferred portions is as follows: Years Ended December 31, 2017 2016 2015 (In thousands) Current tax provision: Federal $ 6,984 $ 3,617 $ 2,933 State 1,551 306 206 8,535 3,923 3,139 Deferred tax provision (benefit): Federal 1,792 344 7 State 77 47 (148 ) Statutory rate change 2,500 (289 ) — Federal and State 4,369 102 (141 ) Change in valuation reserve (1,678 ) (220 ) (161 ) Deferred income tax provision (benefit) 2,691 (118 ) (302 ) Provision for income taxes $ 11,226 $ 3,805 $ 2,837 The reasons for the differences between the statutory federal income tax provision and the actual tax provision (benefit) are summarized as follows: Years Ended December 31, 2017 2016 2015 (Dollars in thousands) Statutory federal tax provision $ 9,700 $ 4,236 $ 3,429 Increase (decrease) resulting from: State taxes, net of federal tax benefit 1,058 233 39 Dividends received deduction (26 ) (41 ) (211 ) Tax-exempt bank-owned life insurance (372 ) (528 ) (351 ) Tax-exempt interest (155 ) (189 ) (222 ) Change in valuation reserve (1,678 ) (220 ) (161 ) Equity incentives 121 339 52 Amortization of low income housing partnership 166 219 — Tax credits utilized (188 ) (286 ) (45 ) Accrual adjustment 23 207 13 Statutory rate change 2,500 (289 ) — Other, net 77 124 294 Tax provision $ 11,226 $ 3,805 $ 2,837 Effective tax rates 40.5 % 30.5 % 28.2 % The components of the net deferred tax asset are as follows: December 31, 2017 2016 (In thousands) Deferred tax assets: Federal $ 6,742 $ 11,700 State 3,416 3,258 Deferred tax assets, gross 10,158 14,958 Valuation reserve (112 ) (1,790 ) Deferred tax assets, net 10,046 13,168 Deferred tax liabilities: Federal (3,050 ) (2,427 ) State (996 ) (595 ) Deferred tax liabilities (4,046 ) (3,022 ) Net deferred tax asset $ 6,000 $ 10,146 The tax effects of each item that give rise to deferred tax assets (liabilities) are as follows: December 31, 2017 2016 (In thousands) Deferred tax assets: Depreciation and amortization $ 279 $ 747 Employee benefit plans and share-based compensation plans 410 571 Allowance for loan losses 5,868 7,660 Contribution carryover 1,122 2,317 Net unrealized loss on securities held as, or transferred, from available for sale — 893 Net unrealized losses on defined benefit pension plan 757 1,270 Deferred rent expense 170 123 Other (31 ) — Valuation reserve (112 ) (1,790 ) Deferred tax liabilities: Deferred loan origination costs (1,338 ) (1,947 ) Net unrealized gain on securities held as, or transferred from, available for sale (166 ) — Gain on exchange of investment in Northeast Retirement Services (959 ) — Other — 302 Net deferred tax asset $ 6,000 $ 10,146 A summary of the change in the net deferred tax asset is as follows: Years Ended December 31, 2017 2016 2015 (In thousands) Balance at beginning of year $ 10,146 $ 10,665 $ 6,233 Deferred tax (provision) benefit (2,691 ) 118 302 Tax effect of changes in accumulated other comprehensive income (1,455 ) (637 ) 4,130 Balance at end of year $ 6,000 $ 10,146 $ 10,665 On December 22, 2017, the Tax Cuts and Jobs Act (the “Act”) became law. The Act amends the Internal Revenue Code to reduce tax rates and modify policies, credits, and deductions for individuals and businesses. For businesses, the Act reduces the corporate tax rate from a maximum of 35% to 21% . The rate reduction is effective January 1, 2018. Under U.S. Generally Accepted Accounting Principles, the Company uses the asset and liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis. 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. As a result of the reduction in the corporate tax rate to 21% from 35% under the Act, the Company has revalued its net deferred tax asset as of December 31, 2017 and as a result, recognized additional income tax expense of $2.5 million in the Company’s consolidated statement of net income for the fourth quarter of 2017. For the year ended December 31, 2016, the Company recorded a tax benefit of $289,000 related to the statutory rate change from 34% to 35% and its impact on the Company's net deferred tax asset. At December 31, 2017 and 2016 , management maintained a valuation reserve in the amount of $112,000 and $1.8 million , respectively, primarily related to state deferred tax assets. During 2017, management determined that due to positive evidence supporting future state profitability, it is more likely than not a tax benefit could be realized for state deferred tax assets with the exception of a portion of the state charitable contribution carryforward. As a result, the Company reversed $1.7 million of valuation allowance with a corresponding benefit to the consolidated statement of net income. At December 31, 2017 , the Company allocated tax expense between the components of the consolidated statements of income as required by the intraperiod allocation rules. The federal income tax reserve for loan losses at the Company’s base year amounted to $1.3 million. If any portion of the reserve is used for purposes other than to absorb loan losses, 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 to only absorb loan losses, a deferred income tax liability of $354,000 has not been provided. The Company’s income tax returns are subject to review and examination by federal and state taxing authorities. The Company is currently open to audit under the applicable statutes of limitations by the Internal Revenue Service and state taxing authorities for the years ended December 31, 2014 through 2017 . Management periodically evaluates the sustainability of tax positions taken. Whenever management estimates the probability of sustaining a tax position is at least more likely than not, the tax position is deemed warranted and is recognized at the largest amount of benefit that is greater than 50% likely of being realized upon settlement. Interest and penalties related to uncertain tax positions are recognized as income tax expense. In the years ended December 31, 2017 and 2016 , $13,000 and $22,000 , respectively, of interest and penalties were paid. No interest or penalties were recorded for the year ended December 31, 2015 .

Equity

Equity	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Equity	EQUITY Minimum regulatory capital requirements The Company (on a consolidated basis) and the Bank are subject to various regulatory capital requirements administered by the federal banking agencies. 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 and the Bank’s consolidated financial statements. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, the Company and the Bank must meet specific capital guidelines that involve quantitative measures of their assets, liabilities, and certain off-balance sheet items as calculated under regulatory accounting practices. The 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. Federal banking regulations include minimum capital ratios as displayed in the following table. Additionally, community banking institutions must maintain a capital conservation buffer of common equity Tier 1 capital in an amount greater than 2.5% of total risk-weighted assets to avoid being subject to limitations on capital distributions and discretionary bonuses. The capital conservation buffer is being phased in over three years , beginning on January 1, 2016, with an initial phase-in of 0.625% . Also, certain deductions from and adjustments to regulatory capital are being phased in over several years. The required minimum conservation buffer is 1.25% as of December 31, 2017 and will increase to 1.875% on January 1, 2018 and 2.5% on January 1, 2019. Management believes that the Company’s capital levels will remain characterized as well-capitalized throughout the phase-in periods. Management believes that the Company will remain characterized as “well capitalized” throughout the phase-in periods. As of December 31, 2017 , the most recent notification from the Federal Deposit Insurance Corporation categorized the Bank as well capitalized under the regulatory framework for prompt corrective action. To be categorized as well capitalized, an institution must maintain minimum ratios as set forth in the following table. There are no conditions or events since the notification that management believes have changed the Bank’s category. Management believes, as of December 31, 2017 and 2016 , that the Company and the Bank meet all capital adequacy requirements to which they are subject. The Company’s and the Bank’s actual capital amounts and ratios as of December 31, 2017 and 2016 are also presented in the following table. Actual Minimum Capital Requirement Minimum To Be Well Capitalized Amount Ratio Amount Ratio Amount Ratio (Dollars in thousands) Blue Hills Bancorp, Inc.: December 31, 2017 Total capital (to risk weighted assets) $ 410,088 19.7 % $ 166,635 8.0 % $ 208,294 10.0 % Tier 1 capital (to risk weighted assets) 389,211 18.7 124,977 6.0 166,635 8.0 Common equity Tier 1 (to risk weighted assets) 389,211 18.7 93,732 4.5 135,391 6.5 Tier 1 capital (to average assets) 389,211 14.9 104,278 4.0 130,348 5.0 December 31, 2016 Total capital (to risk weighted assets) 395,325 20.5 154,471 8.0 193,089 10.0 Tier 1 capital (to risk weighted assets) 376,575 19.5 115,854 6.0 154,471 8.0 Common equity Tier 1 (to risk weighted assets) 376,575 19.5 86,890 4.5 125,508 6.5 Tier 1 capital (to average assets) 376,575 16.0 94,166 4.0 117,708 5.0 Blue Hills Bank: December 31, 2017 Total capital (to risk weighted assets) 341,175 16.4 166,391 8.0 207,988 10.0 Tier 1 capital (to risk weighted assets) 320,298 15.4 124,793 6.0 166,391 8.0 Common equity Tier 1 (to risk weighted assets) 320,298 15.4 93,595 4.5 135,192 6.5 Tier 1 capital (to average assets) 320,298 12.3 104,137 4.0 130,171 5.0 December 31, 2016 Total capital (to risk weighted assets) 313,457 16.3 154,196 8.0 192,745 10.0 Tier 1 capital (to risk weighted assets) 294,707 15.3 115,647 6.0 154,196 8.0 Common equity Tier 1 (to risk weighted assets) 294,707 15.3 86,735 4.5 125,284 6.5 Tier 1 capital (to average assets) 294,707 12.5 94,099 4.0 117,623 5.0 Preferred stock The Company has authorized 50,000,000 shares, zero par value of Preferred Stock. As of December 31, 2017 , there were no shares issued or outstanding. Restrictions on dividends, loans and advances Federal and state banking regulations place certain restrictions on dividends paid and loans or advances made by the Bank to the Company. The total amount of dividends which may be paid in any calendar year cannot exceed the Bank’s net income for the current year, plus the Bank’s net income retained for the two previous years, without regulatory approval. Loans or advances are limited to 10 percent of the Bank’s capital stock and surplus on a secured basis. At December 31, 2017 , the Bank's retained earnings available for the payment of dividends was $36.5 million . Funds available for loans or advances by the Bank to the Company amounted to $31.9 million . In addition, as a result of regulatory capital requirements, $166.4 million of the Company's $328.7 million equity in the net assets of the Bank was restricted at December 31, 2017 . In addition, dividends paid by the Bank to the Company would be prohibited if the effect thereof would cause the Bank’s capital to be reduced below applicable capital requirements. The payment of dividends by the Company is subject to Maryland law. The Company can pay dividends on its common stock if, after giving effect to such distribution, (i) it would be able to pay its indebtedness as the indebtedness comes due in the usual course of business and (ii) its total assets exceed the sum of its liabilities and the amount needed, if Blue Hills Bancorp were to be dissolved at the time of the distribution, to satisfy the preferential rights upon dissolution of any holders of capital stock who have a preference in the event of dissolution; provided, however, that even if the Company's assets are less than the amount necessary to satisfy the requirement set forth in (ii) above, the Company may make a distribution from: (A) the Company's net earnings for the fiscal year in which the distribution is made; (B) the Company's net earnings for the preceding fiscal year; or (C) the sum of the Company's net earnings for the preceding eight fiscal quarters. The holders of common stock of the Company will be entitled to receive and share equally in dividends as may be declared by our Board of Directors out of funds legally available. If the Company issues shares of preferred stock, the holders thereof may have a priority over the holders of the common stock with respect to dividends. Liquidation account At the time of conversion to a stock holding company, the Company substantially restricted retained earnings by establishing a liquidation account and the Bank established a parallel liquidation account. The liquidation accounts amounted to $49.0 million and $61.0 million at December 31, 2017 and 2016 , respectively, and are maintained for the benefit of eligible deposit account holders who continue to maintain their accounts at the Bank after the conversion. The liquidation accounts will be reduced annually to the extent that eligible account holders have reduced their qualifying deposits. Subsequent increases will not restore an eligible account holder’s interest in the liquidation accounts. In the event of a complete liquidation of the Bank, each account holder will be entitled to receive a distribution from the liquidation accounts as described in the Plan of Conversion. Neither the Company nor the Bank may declare or pay a cash dividend on its common stock if such dividend would cause its regulatory capital to be reduced below the amount required to maintain its respective liquidation account.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Employee Benefit Plans	EMPLOYEE BENEFIT PLANS Pension plan The Company historically provided basic and supplemental pension benefits for eligible employees through the Savings Banks Employees Retirement Association’s (“SBERA”) Pension Plan (the “Plan”). The Company accounts for the defined benefit pension plan using an actuarial model that allocates pension costs over the service period of employees in the plan. The Company accounts for the over-funded or under-funded status of its defined benefit plan as an asset or liability on its consolidated balance sheets and recognizes changes in the funded status in the year in which the changes occur as other comprehensive income or loss. The Company amended its defined benefit pension plan to freeze all participants effective October 31, 2014. Accumulated benefits for participants earned through the end of October 2014 will remain secured by the Plan assets. Information pertaining to the Plan is as follows: Years Ended December 31, 2017 2016 2015 (In thousands) Change in plan assets: Fair value of plan assets at beginning of year $ 9,811 $ 8,814 $ 9,443 Actual return (loss) on plan assets 1,414 847 (304 ) Employer contribution 1,110 470 — Benefits paid (178 ) (320 ) (325 ) Settlement payments (1,394 ) — — Fair value of plan assets at end of year 10,763 9,811 8,814 Change in benefit obligation: Benefit obligation at beginning of year 11,896 10,772 10,135 Interest cost 390 422 401 Actuarial loss 481 1,022 561 Benefits paid (178 ) (320 ) (325 ) Settlement payments (1,394 ) — — Benefit obligation at end of year 11,195 11,896 10,772 Funded status and accrued liability at end of year $ (432 ) $ (2,085 ) $ (1,958 ) Accumulated benefit obligation at end of year $ 11,195 $ 11,896 $ 10,772 At December 31, 2017 and 2016 , the discount rate used to determine the benefit obligation was 3.43% and 3.86% , respectively. The components of net periodic pension cost (benefit) are as follows: Years Ended December 31, 2017 2016 2015 (In thousands) Interest cost 390 422 401 Expected return on plan assets (758 ) (720 ) (745 ) Amortization of net actuarial loss 297 271 110 Settlement loss 317 — — Net periodic pension cost (benefit) $ 246 $ (27 ) $ (234 ) The assumptions used to determine net periodic pension cost (benefit) are as follows: Years Ended December 31, 2017 2016 2015 Discount rate 3.86 % 4.01 % 4.00 % Expected long-term rate of return on plan assets 8.00 % 8.00 % 8.00 % The Company has selected its assumption with respect to the expected long-term rate of return based on prevailing yields on high-quality, fixed-income investments increased by a premium for equity return expectations. SBERA offers a common and collective trust as the underlying investment structure for pension plans participating in SBERA. The target allocation mix for the common and collective trust portfolio calls for an equity-based investment range from 40% to 64% of total portfolio assets. The remainder of the portfolio is allocated to fixed income from 15% to 25% and other investments including global asset allocation and hedge funds from 25% to 41% . The Trustees of SBERA, through the Investment Committee, select investment managers for the common and collective trust portfolio. A professional investment advisory firm is retained by the Investment Committee to provide allocation analysis, performance measurement and to assist with manager searches. The overall investment objective is to diversify equity investments across a spectrum of investment types to limit risks from large market swings. The fair value of major categories of the Company’s pension plan assets are summarized below: Level 1 Level 2 Level 3 Total Fair Value (In thousands) December 31, 2017 Collective funds $ 420 $ — $ — $ 420 Equity securities 2,413 — — 2,413 Mutual funds 2,079 — — 2,079 Total investments measured in the fair value hierarchy 4,912 — — 4,912 Investments measured at net asset value (a) — — — 5,851 $ 4,912 $ — $ — $ 10,763 December 31, 2016 Collective funds $ 681 $ — $ — $ 681 Equity securities 1,929 — — 1,929 Mutual funds 1,209 — — 1,209 Short-term investments 124 — — 124 $ 3,943 $ — $ — $ 3,943 Investments measured at net asset value (a) — — — 5,868 $ 3,943 $ — $ — $ 9,811 (a) In accordance with FASB ASC 820, Fair Value Measurements , certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy. There are no unfunded commitments or redemption restrictions for these investments, which can be redeemed on a daily basis. The fair value hierarchy above was received from SBERA, the plan administrator. The Plan assets measured at fair value in Level 1 are based on quoted market prices in an active exchange market. Plan assets measured at fair value in Level 2 are based on pricing models that consider standard input factors such as observable market data, benchmark yields, interest rate volatilities, broker/dealer quotes, credit spreads and new issue data. Plan assets measured at fair value in Level 3 are based on unobservable inputs, which include the SBERA’s assumptions and the best information available under the circumstance. Estimated future benefit payments, assuming employees retire at age 65 and take normal distribution payments, are as follows: Amount Year Ending December 31, (In thousands) 2018 $ 843 2019 505 2020 684 2021 933 2022 628 2023-2027 2,880 No further contributions are anticipated during 2018. 401(k) Plan The Company has a 401(k) Plan whereby each employee having completed at least three months of service beginning with their date of employment, automatically becomes an eligible participant in the 401(k) Plan. Employees may contribute a portion of their compensation subject to certain limits based on Federal tax laws. The Company provides a 4% matching contribution equal to 100% of an employee’s first 3% of deferral and 50% of the next 2% deferral. For the years ended December 31, 2017 , 2016 and 2015 expenses related to the plan were $670,000 , $784,000 , and $610,000 , respectively. Short-term Incentive Compensation Plan All employees meeting specified service requirements are eligible to participate in the discretionary Short-term Incentive Compensation Plan. The purpose of the plan is to motivate and reward employees for achieving strategic objectives through a goals program. The Company recorded expenses of $2.9 million , $2.5 million , and $2.3 million for achievement of the 2017 , 2016 and 2015 goals, respectively. Employee Stock Ownership Plan The Company maintains the ESOP to provide eligible employees the opportunity to own Company stock. This plan is a tax-qualified retirement plan for the benefit of Company employees. The Company, through its wholly-owned subsidiary, Blue Hills Funding Corporation, granted a loan to the ESOP in July of 2014 for the purchase of 2,277,345 shares of the Company’s common stock at a price of $10.00 per share. Principal and interest is payable annually over 30 years at a rate per annum equal to the Prime Rate ( 4.50% at December 31, 2017 ). Loan payments are funded by cash contributions from the Company and dividends received on unallocated shares. The loan is secured by the shares purchased, which are held in a suspense account for allocation among participants as the loan is repaid. The balance of the ESOP loan at December 31, 2017 was $20.5 million . Contributions are allocated to eligible participants on the basis of compensation, subject to federal tax limits. The number of shares committed to be released per year is 75,912 through 2043. Shares held by the ESOP include the following: December 31, 2017 2016 Allocated 219,860 149,613 Committed to be allocated 75,912 75,912 Unallocated 1,973,699 2,049,608 2,269,471 2,275,133 The fair value of unallocated shares was $39.7 million and $38.4 million at December 31, 2017 and 2016 , respectively. Total compensation expense recognized in connection with the ESOP amounted to $1.4 million , $1.1 million , and $1.1 million for the years ended December 31, 2017 , 2016 and 2015 , respectively.

Stock Based Compensation

Stock Based Compensation	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Based Compensation	STOCK BASED COMPENSATION Under the Blue Hills Bancorp, Inc. 2015 Equity Incentive Plan (the "Equity Plan"), the Company may grant options, restricted stock, restricted units or performance awards to its directors, officers and employees. Both incentive stock options and non-qualified stock options may be granted under the Equity Plan, with the total number of shares reserved for options equaling 2,846,681 . The exercise price of each option equals the market price of the Company’s stock on the date of grant and the maximum term of each option is ten years . A total of 1,138,673 shares are reserved for awards of restricted stock or restricted units. The vast majority of options and awards vest ratably over five years. The fair value of shares awarded is based on the market price at the date of grant. Expense related to options and restricted stock granted to employees is recognized in salaries and benefits within noninterest expense and expense related to options and restricted stock granted to directors is recognized as directors' fees within noninterest expense. The Company has standard form agreements used for stock option and restricted stock awards and generally provide that: (1) any unvested options or unvested restricted stock vest upon a Change in Control; and, that (2) any stock options which vest pursuant to a Change in Control, which is an event described in Section 280G of the Internal Revenue Code of 1986, will be cashed out at the difference between the acquisition price and the exercise price of the stock option. Stock Options The fair value of each option grant is estimated on the date of the grant using the Black-Scholes option-pricing model with the following assumptions: • Volatility is based on peer group volatility because the Company does not have a sufficient trading history. • Expected life represents the period of time that the option is expected to be outstanding, taking into account the contractual term, and the vesting period. • Expected dividend yield is based on the Company's history and expectation of dividend payouts. • The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant for a period equivalent to the expected life of the option. The Company made the following awards of options to purchase shares of common stock during the years ended December 31, 2017 , 2016 and 2015 : 2017 2016 2015 Options granted 412,100 55,000 2,434,000 Vesting period (years) 5 5 5 Term (years) 10 10 10 Fair value calculation assumptions: Expected volatility 26.91%-27.43% 28.47 % 28.85 % Expected life (years) 6.5 6.5 6.5 Expected dividend yield 0.71%-2.22% 0.58 % 0.54 % Risk free interest rate 1.87%-2.16% 1.38 % 1.55 % Fair value per option $4.07-$5.31 $ 4.02 $ 4.23 Weighted average grant date fair value $ 5.09 $ 4.02 $ 4.23 A summary of the status of the Company's stock option grants for the year ended December 31, 2017 is presented in the table below: Stock Option Awards Weighted Average Exercise Price Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value Balance at January 1, 2017 2,449,670 $ 14.06 Granted 412,100 18.22 Forfeited (159,650 ) 14.18 Exercised (17,470 ) 13.9 — $ 77,000 Outstanding at December 31, 2017 2,684,650 $ 14.70 7.98 $ 14,506,000 Exercisable at December 31, 2017 925,990 $ 14.07 7.75 $ 5,584,000 Unrecognized compensation cost inclusive of directors' options at December 31, 2017 $6,950,000 Weighted average remaining recognition period (years) 3.12 For the years ended December 31, 2017 , 2016 and 2015 , stock-based compensation expense applicable to the stock options was $2.3 million , $2.1 million and $473,000 , respectively. The recognized tax benefit related to this expense was $657,000 , $502,000 and $112,000 , respectively. Restricted Stock Shares issued upon vesting may be either authorized but unissued shares or reacquired shares held by the Company. Any shares not issued because vesting requirements are not met will again be available for issuance under the plan. The fair market value of shares awarded, based on the market price at the date of grant, is recorded as unearned compensation and amortized over the applicable vesting period. Of the restricted shares granted 40,000 are performance based, of which 6,000 have vested, and 32,000 remain unvested. There were 2,000 performance shares forfeited during the year ended December 31, 2017 . The following table presents the activity in non-vested stock awards under the Equity Plan for the year ended December 31, 2017 : Outstanding Restricted Stock Awards Weighted Average Grant Price Non-vested stock awards at January 1, 2017 816,070 $ 14.06 Granted 184,695 18.25 Vested (185,028 ) 14.06 Forfeited (85,317 ) 14.11 Non-vested stock awards at December 31, 2017 730,420 $ 15.11 Unrecognized compensation cost inclusive of directors' awards at December 31, 2017 $ 9,704,000 Weighted average remaining recognition period (years) 3.17 For the years ended December 31, 2017 , 2016 and 2015 , shared-based compensation expense applicable to restricted stock awards was $3.2 million , $2.8 million and $651,000 , respectively. The recognized tax benefit related to this expense was $1.3 million , $987,000 and $228,000 , respectively.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings Per Share	EARNINGS PER SHARE Earnings per share consisted of the following components for the years ended December 31, 2017 , 2016 and 2015 . 2017 2016 2015 (Dollars in thousands, except per share amounts) Net income applicable to common stock $ 16,489 $ 8,653 $ 7,227 Average number of common shares outstanding 26,849,253 27,464,996 28,460,077 Less: Average unvested restricted stock awards (851,779 ) (957,364 ) (231,652 ) Less: Average unallocated ESOP shares (2,011,652 ) (2,087,227 ) (2,163,478 ) Average number of common shares outstanding used to calculate basic earnings per common share 23,985,822 24,420,405 26,064,947 Effect of dilutive stock options 248,161 — — Effect of dilutive unvested restricted stock awards 248,431 120,524 4,642 Average number of common shares outstanding used to calculate diluted earnings per common share 24,482,414 24,540,929 26,069,589 Earnings per common share: Basic $ 0.69 $ 0.35 $ 0.28 Diluted $ 0.67 $ 0.35 $ 0.28 For the years ended December 31, 2017 , 2016 and 2015 , options for 407,950 , 2,486,000 and 2,434,000 shares, respectively, were not included in the computation of diluted earnings per share because to do so would have been antidilutive as the weighted average exercise prices of the stock options exceeded the weighted average market price for the periods presented.

Other Commitments and Contingen

Other Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Other Commitments and Contingencies	OTHER COMMITMENTS AND CONTINGENCIES In the normal course of business, there are outstanding commitments and contingencies which are not reflected in the accompanying consolidated financial statements. Loan commitments The Company is a party to financial instruments with off-balance sheet risk in the normal course of business to meet the financing needs of its customers. These financial instruments include commitments to extend credit, which involve elements of credit and interest rate risk in excess of the amount recognized in the accompanying consolidated balance sheets. The contract amount of these instruments reflects the extent of involvement the Company has in these particular classes of financial instruments. The Company’s exposure to credit loss is represented by the contractual amount of the instruments. The Company uses the same credit policies in making commitments as it does for on-balance sheet instruments. Financial instruments whose contract amounts represent credit risk consist of: December 31, 2017 2016 (In thousands) Commitments to originate loans $ 66,020 $ 51,622 Letters of credit 6,314 3,277 Unused lines-of-credit: Commercial 203,631 164,185 Home equity 73,369 55,344 Consumer 15,819 15,995 Undisbursed construction loans 82,177 96,169 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 and unadvanced funds on lines-of-credit generally have fixed expiration dates and may expire without being drawn upon. Therefore, the total commitment amount does not necessarily represent future cash requirements. The Company evaluates each customer’s creditworthiness on a case-by-case basis. These financial instruments are primarily secured by mortgage liens on real estate. Operating lease commitments Pursuant to the terms of noncancelable lease agreements in effect at December 31, 2017 , pertaining to premises, future minimum rent commitments are as follows: Year Ending December 31, Amount (In thousands) 2018 $ 2,698 2019 2,490 2020 2,409 2021 2,278 2022 2,286 Thereafter 9,640 $ 21,801 Rent expense for years ended December 31, 2017 , 2016 and 2015 amounted to $3.0 million , $2.2 million and $1.6 million , respectively. Certain leases contain renewal options for up to 30 years. The cost of such options is not included above. Other Commitments Effective January 1, 2014, the Bank entered into an agreement for the naming rights of a Boston waterfront music venue. The agreement spans a ten -year period, with an opt-out option at the end of year seven, where the Bank paid $390,000 during the first year with 5% annual increases in subsequent years. Total expenses related to the agreement were $454,000 , $430,000 and $410,000 for the years ended December 31, 2017 , 2016 and 2015 , respectively. Employment and change in control agreements The Company has entered into an employment agreement with its President and Chief Executive Officer that generally provides for a specified minimum annual compensation and the continuation of certain benefits currently received. Employment may be terminated for cause, as defined, or termination without cause, or upon certain change in control events, which would result in a cash severance payment that will be determined based on the event. The agreement has an initial term of three years, with automatic one -year extensions on the anniversary date of the agreement. The Company has also entered into change in control agreements with certain members of management which provide for the continuation of base salaries for specified periods of time in the event of involuntary termination without cause or termination for good reason in the event of a change in control. Contingencies The Company is involved in various litigation and other legal claims that arise in the normal course of business. On December 30, 2014, a former employee filed a complaint in U.S. Federal District Court of Massachusetts, claiming wrongful termination following a whistleblower claim. This complaint alleged violations of the Federal Deposit Insurance Act, the False Claims Act, and the Family and Medical Leave Act ("FMLA"). The former employee withdrew all of his claims after reaching a confidential settlement agreement in January of 2018. Both parties provided mutual releases of all claims and have executed a confidentiality agreement. All costs related to the case were reflected in the consolidated statements of net income as of December 31, 2017.

On Balance Sheet Derivative Ins

On Balance Sheet Derivative Instruments and Hedging Activities	12 Months Ended
	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
On Balance Sheet Derivative Instruments and Hedging Activities	ON BALANCE SHEET DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES The Company is party to derivative financial instruments in the normal course of business to manage exposure to fluctuations in interest rates and to meet the needs of commercial customers. These financial instruments have been generally limited to loan level interest rate swap agreements, which are entered into with counterparties that meet established credit standards. These transactions involve both credit and market risk. The notional amounts are amounts on which calculations, payments, and the value of the derivatives are based. Notional amounts do not represent direct credit exposures. The fair value of the derivative instruments is reflected on the Company’s consolidated balance sheet as other assets or accrued expenses and other liabilities as appropriate. Changes in the fair value of these agreements are recorded in miscellaneous income in the consolidated statements of net income. The Company did not have any fair value hedges or cash flow hedges at December 31, 2017 and 2016 . The table below presents information about derivative financial instruments not designated as hedging instruments at December 31, 2017 and 2016 . Derivative Gains Derivative Losses Notional Amount Fair Value Notional Amount Fair Value (In thousands) December 31, 2017 Commercial loan level interest rate swap agreements $ 582,388 $ 8,741 $ 582,388 $ 8,741 Other contracts 27,689 25 54,293 44 Total derivatives $ 610,077 $ 8,766 $ 636,681 $ 8,785 December 31, 2016 Commercial loan level interest rate swap agreements $ 419,488 $ 9,016 $ 419,488 $ 8,932 Other contracts 15,865 8 33,045 56 Total derivatives $ 435,353 $ 9,024 $ 452,533 $ 8,988 The Company is exposed to credit-related losses in the event of nonperformance by the counterparties to these agreements. The Company controls the credit risk of its financial contracts through credit approvals, limits and monitoring procedures, and does not expect any counterparties to fail their obligations. The Company has minimum collateral posting thresholds with certain of its interest rate swap derivative counterparties. Other contracts represent risk participation agreements on commercial loan level interest rate swap agreements. The Company has entered into risk participation agreements with the correspondent institutions to share in any interest rate swap gains or losses incurred as a result of the commercial loan customers’ termination of a loan level interest rate swap agreement prior to maturity. The Company records these risk participation agreements at fair value. Mortgage Banking Derivatives The Company enters into commitments to fund residential mortgage loans at specified rates and times in the future, with the intention that loans will subsequently be sold in the secondary market. Mortgage loan commitments are referred to as derivative loan commitments if the loan that will result from exercise of the commitment will be held for sale upon funding. These commitments are recognized at fair value on the consolidated balance sheet in other assets and other liabilities with changes in their fair values recorded in non-interest income. Outstanding loan commitments expose the Company to the risk that the price of the loans arising from exercise of the loan commitment might change from inception of the rate lock to funding of the loan due to changes in mortgage interest rates. If interest rates increase, the value of these loan commitments decreases. Conversely, if interest rates decrease, the value of these loan commitments increases. At December 31, 2017 and 2016, the notional amount of mortgage loan commitments amounted to $16.4 million and $6.8 million , respectively. To protect against the price risk inherent in derivative loan commitments, the Company utilizes “best efforts” forward loan sale commitments to mitigate the risk of potential decreases in the values of loans that would result from the exercise of the derivative loan commitments. With a “best efforts” contract, the Company commits to deliver an individual mortgage loan of a specified principal amount and quality to an investor if the loan to the underlying borrower closes. Generally, the price the investor will pay the seller for an individual loan is specified prior to the loan being funded (e.g., on the same day the lender commits to lend funds to a potential borrower). The Company expects that these forward sale commitments will experience changes in fair value opposite to the change in fair value of derivative loan commitments. The notional amount of forward loan sale commitments at December 31, 2017 and 2016 was $25.3 million and $9.5 million , respectively. The fair value of such commitments as of December 31, 2017 and 2016 are outlined below: Assets Liabilities Balance Sheet Location Fair Value Balance Sheet Location Fair Value (In thousands) December 31, 2017 Mortgage loan commitments Other Assets $ 210 Other Liabilities $ 36 Forward loan sale commitments Other Assets 22 Other Liabilities 69 Total $ 232 $ 105 December 31, 2016 Mortgage loan commitments Other Assets $ 111 Other Liabilities $ 3 Forward loan sale commitments Other Assets 15 Other Liabilities 74 Total $ 126 $ 77

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASURMENTS Determination of fair value The Company uses fair value measurements to record fair value adjustments to certain assets and liabilities and to determine fair value disclosures. Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Fair value is best determined based upon quoted market prices. However, in many instances, there are no quoted market prices for the Company’s various assets and liabilities. In cases where quoted market prices are not available, fair values are based on estimates using present value or other valuation techniques. Those techniques are significantly affected by the assumptions used, including the discount rate and estimates of future cash flows. Accordingly, the fair value estimates may not be realized in an immediate settlement of the assets and liabilities. The following methods and assumptions were used by the Company in estimating fair value disclosures for financial instruments: Cash and cash equivalents : The carrying amounts of cash and due from banks and short-term investments approximate fair value. Securities: All fair value measurements are obtained from a third-party pricing service and are not adjusted by management. The securities measured at fair value in Level 1 are based on quoted market prices in an active exchange market. These securities include U.S. Treasury securities and marketable equity securities. All other securities are measured at fair value in Level 2 based on pricing models that consider standard input factors such as observable market data, benchmark yields, interest rate volatilities, broker/dealer quotes, credit spreads and new issue data. Federal Home Loan Bank stock : The carrying value of Federal Home Loan Bank stock approximates fair value based on the redemption provisions of the Federal Home Loan Bank. Loans held for sale : Fair values are based on commitments in effect from investors or prevailing market prices. Loans : Fair values are estimated using discounted cash flow analyses, using market interest rates currently being offered for loans with similar terms to borrowers of similar credit quality. Fair values for non-performing loans are estimated using discounted cash flow analyses or underlying collateral values, where applicable. Accrued interest receivable : The carrying amount of accrued interest receivable approximates fair value. Deposits : The fair values for non-certificate accounts are, by definition, equal to the amount payable on demand at the reporting date (i.e., their carrying amounts). Fair values for certificate accounts are estimated using a discounted cash flow calculation that applies market interest rates currently being offered on certificates to a schedule of aggregated expected monthly maturities on time deposits. Borrowings : The fair values of borrowings are estimated using discounted cash flow analyses based on the current borrowing rates in the market for similar types of borrowing arrangements. Interest rate swap agreements : The fair values of interest rate swap agreements are based on a valuation model that uses primarily observable inputs, such as benchmark yield curves and interest rates and also include the value associated with counterparty credit risk. 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. Forward loan sale commitments and derivative loan commitments : Fair values of forward loan sale commitments and derivative loan commitments are based on fair values of the underlying mortgage loans and, for derivative loan commitments, fair values also include the value of servicing, deferred origination fees/costs and the probability of such commitments being exercised. Significant judgment and estimation is required in determining these fair value measurements. Off-balance sheet instruments : Fair values for off-balance sheet lending commitments are based on fees currently charged to enter into similar agreements, taking into account the remaining terms of the agreements and the counterparties’ credit standing. The estimated fair value of off-balance sheet financial instruments at December 31, 2017 and 2016 , was immaterial since fees charged are not material. Assets and liabilities measured at fair value on a recurring basis Assets and liabilities measured at fair value on a recurring basis are summarized below: Level 1 Level 2 Level 3 Total Fair Value (In thousands) December 31, 2017 Assets Marketable equity securities $ 9,720 $ — $ — $ 9,720 Derivative assets: Interest rate swap agreements — 8,766 — 8,766 Forward loan sale commitments — — 22 22 Mortgage loan commitments — — 210 210 Total assets $ 9,720 $ 8,766 $ 232 $ 18,718 Liabilities Derivative liabilities: Interest rate swap agreements $ — $ 8,785 $ — $ 8,785 Forward loan sale commitments — — 69 69 Mortgage loan commitments — — 36 36 Total liabilities $ — $ 8,785 $ 105 $ 8,890 December 31, 2016 Assets Securities available for sale: Debt securities $ — $ 161,668 $ — $ 161,668 Marketable equity securities 43,168 — — 43,168 Derivative assets: Interest rate swap agreements — 9,024 — 9,024 Forward loan sale commitments — — 15 15 Mortgage loan commitments — — 111 111 Total assets $ 43,168 $ 170,692 $ 126 $ 213,986 Liabilities Derivative liabilities: Interest rate swap agreements $ — $ 8,988 $ — $ 8,988 Forward loan sale commitments — — 74 74 Mortgage loan commitments — — 3 3 Total liabilities $ — $ 8,988 $ 77 $ 9,065 Assets measured at fair value on a non-recurring basis The Company may also be required, from time to time, to measure certain assets at fair value on a non-recurring basis in accordance with generally accepted accounting principles. These adjustments to fair value usually result from application of lower-of-cost-or-market accounting or write-downs of individual assets. There are no liabilities measured at fair value on a non-recurring basis. The following table summarizes the fair value hierarchy applicable to assets measured at fair value on a non-recurring basis: December 31, 2017 December 31, 2016 Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 (In thousands) Impaired loans $ — $ — $ 2,214 $ — $ — $ 136 The following table summarizes the total losses on assets measured at fair value on a non-recurring basis for the years ended December 31, 2017 , 2016 and 2015 . Years Ended December 31, 2017 2016 2015 (In thousands) Impaired loans $ (5 ) $ (2,911 ) $ (404 ) Gains and losses applicable to impaired loans are based on the appraised value of the underlying collateral, discounted as necessary due to management’s estimates of changes in market conditions. The losses applicable to impaired loans are not recorded as a direct adjustment to current earnings or comprehensive income, but rather as a component in determining the overall adequacy of the allowance for loan losses. Adjustments to the estimated fair value of impaired loans may result in increases or decreases to the provision for loan losses. Summary of fair values of financial instruments The estimated fair values, and related carrying amounts, of the Company’s financial instruments are as follows. Certain financial instruments and all nonfinancial instruments are exempt from disclosure requirements. Accordingly, the aggregate fair value amounts presented herein do not represent the underlying fair value of the Company. Carrying Fair Value Level 1 Level 2 Level 3 Total (In thousands) December 31, 2017 Financial assets: Cash and cash equivalents $ 46,167 $ 46,167 $ — $ — $ 46,167 Securities available for sale 9,720 9,720 — — 9,720 Securities held to maturity 303,716 — 299,114 — 299,114 Federal Home Loan Bank stock 12,105 — — 12,105 12,105 Loans and loans held for sale, net 2,195,139 — — 2,174,871 2,174,871 Accrued interest receivable 6,438 — — 6,438 6,438 Financial liabilities: Deposits 2,039,869 — — 2,036,150 2,036,150 Borrowings 205,000 — 203,913 — 203,913 On-balance sheet derivative financial instruments: Derivative assets: Interest rate swap agreements 8,766 — 8,766 — 8,766 Forward loan sale commitments 22 — — 22 22 Mortgage loan commitments 210 — — 210 210 Derivative liabilities: Interest rate swap agreements: 8,785 — 8,785 — 8,785 Forward loan sale commitments 69 — — 69 69 Mortgage loan commitments 36 — — 36 36 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total (In thousands) December 31, 2016 Financial assets: Cash and cash equivalents $ 30,496 $ 30,496 $ — $ — $ 30,496 Securities available for sale 204,836 43,168 161,668 — 204,836 Securities held to maturity 201,027 — 198,093 — 198,093 Federal Home Loan Bank stock 13,352 — — 13,352 13,352 Loans and loans held for sale, net 1,915,632 — — 1,903,978 1,903,978 Accrued interest receivable 6,057 — — 6,057 6,057 Financial liabilities: Deposits 1,808,687 — — 1,808,629 1,808,629 Borrowings 251,000 — 250,648 — 250,648 On-balance sheet derivative financial instruments: Derivative assets: Interest rate swap agreements 9,024 — 9,024 — 9,024 Forward loan sale commitments 15 — — 15 15 Mortgage loan commitments 111 — — 111 111 Derivative liabilities: Interest rate swap agreements: 8,988 — 8,988 — 8,988 Forward loan sale commitments 74 — — 74 74 Mortgage loan commitments 3 — — 3 3

Other Comprehensive Income

Other Comprehensive Income	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Other Comprehensive Income	OTHER COMPREHENSIVE INCOME Accounting principles generally require that recognized revenues, expenses, gains and losses be included in net income. Although certain changes in assets and liabilities are reported as a separate component of equity on the consolidated balance sheets, such items, along with net income, are components of comprehensive income. The components of accumulated other comprehensive loss, included in stockholders' equity, are as follows: December 31, 2017 2016 (In thousands) Securities available for sale: Net unrealized gain (loss) $ 283 $ (3,087 ) Tax effect (107 ) 1,007 Net-of-tax amount 176 (2,080 ) Stranded tax effect related to the Act (see Note 2) (33 ) — Securities available for sale, net 143 (2,080 ) Securities held to maturity: Net unrealized gain on transferred securities 250 337 Tax effect (59 ) (114 ) Net-of-tax amount 191 223 Stranded tax effect related to the Act (see Note 2) (7 ) — Securities held to maturity, net 184 223 Defined benefit pension plan: Unrecognized net actuarial loss (2,694 ) (3,482 ) Tax effect 757 1,270 Net-of-tax amount (1,937 ) (2,212 ) Stranded tax effect related to the Act (see Note 2) 157 — Defined benefit pension plan, net (1,780 ) (2,212 ) $ (1,453 ) $ (4,069 ) Actuarial losses of $266,000 , included in accumulated other comprehensive loss at December 31, 2017, are expected to be recognized as a component of net periodic pension cost, included in salaries and employee benefits expense, during the year ending December 31, 2018.

Condensed Financial Statements

Condensed Financial Statements of Parent Company	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Financial Statements of Parent Company	CONDENSED FINANCIAL STATEMENTS OF PARENT COMPANY Financial information pertaining only to Blue Hills Bancorp, Inc. is as follows: December 31, BALANCE SHEETS 2017 2016 (In thousands) Assets Cash balances at Blue Hills Bank $ 42,111 $ 66,326 Total cash and cash equivalents 42,111 66,326 Investment in Blue Hills Bank 328,740 303,036 Investment in Blue Hills Funding Corp. 26,417 25,165 Other assets 21,146 13,499 Total assets $ 418,414 $ 408,026 Liabilities and Stockholders' Equity Liability to ESOP $ 20,533 $ 20,995 Accrued expenses 75 124 Stockholders' equity 397,806 386,907 Total liabilities and stockholders' equity $ 418,414 $ 408,026 Years Ended December 31, 2017 2016 2015 STATEMENTS OF NET INCOME (In thousands) Operating expenses $ 2,105 $ 2,478 $ 1,860 Loss before income taxes and equity in undistributed net income of subsidiaries $ (2,105 ) $ (2,478 ) $ (1,860 ) Applicable income tax benefit (451 ) (758 ) (1,112 ) Loss before equity in income of subsidiaries (1,654 ) (1,720 ) (748 ) Equity in undistributed net income of subsidiaries 18,143 10,373 7,975 Net income $ 16,489 $ 8,653 $ 7,227 Years Ended December 31, 2017 2016 2015 STATEMENTS OF CASH FLOWS (In thousands) Cash flows from operating activities: Net income $ 16,489 $ 8,653 7,227 Adjustments to reconcile net income to net cash provided by (used for) operating activities: Equity in undistributed net income of subsidiaries (18,143 ) (10,373 ) (7,975 ) Excess tax benefit from deferred and stock based compensation — (105 ) (166 ) Net change in other assets (1,164 ) 11,625 (1,157 ) Net change in other liabilities (49 ) 97 (241 ) Net cash provided by (used for) operating activities (2,867 ) 9,897 (2,312 ) Cash flows used for investing activities: Investment in Blue Hills Bank (6,228 ) (16,844 ) (3,929 ) Net cash used for investing activities (6,228 ) (16,844 ) (3,929 ) Cash flows used for financing activities: Excess tax benefit from deferred and stock based compensation — 105 166 Repurchase of common stock — (24,432 ) (13,121 ) Share redemption for tax withholdings (983 ) (730 ) (439 ) Proceeds from exercise of stock options 243 40 — Common and preferred stock dividends paid (14,380 ) (2,675 ) (1,032 ) Net cash used for financing activities (15,120 ) (27,692 ) (14,426 ) Net change in cash and cash equivalents (24,215 ) (34,639 ) (20,667 ) Cash and cash equivalents at beginning of year 66,326 100,965 121,632 Cash and cash equivalents at end of year $ 42,111 $ 66,326 $ 100,965

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (Unaudited)	SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) First Quarter Second Quarter Third Quarter Fourth Quarter 2017 2016 2017 2016 2017 2016 2017 2016 (In thousands, except share data) Interest and dividend income $ 19,781 $ 16,063 $ 20,574 $ 16,356 $ 21,545 $ 17,685 $ 22,875 $ 19,434 Interest expense 3,900 2,862 4,166 3,040 4,591 3,190 5,081 3,484 Net interest and dividend income 15,881 13,201 16,408 13,316 16,954 14,495 17,794 15,950 Provision (credit) for loan losses 57 (27 ) 1,118 1,113 242 2,872 681 927 Other noninterest income 1,891 1,621 3,582 2,147 2,826 3,834 2,930 3,509 Realized securities gains (losses), net (1,022 ) (244 ) 928 664 — 298 — 298 Gain on exchange of investment in Northeast Retirement Services 5,947 — — — — — — — Total noninterest income 6,816 1,377 4,510 2,811 2,826 4,132 2,930 3,807 Total noninterest expense 13,400 12,068 13,366 12,935 13,355 13,234 14,185 13,509 Provision for income taxes 1,753 870 2,566 721 2,342 891 4,565 1,323 Net income $ 7,487 $ 1,667 $ 3,868 $ 1,358 $ 3,841 $ 1,630 $ 1,293 $ 3,998 Basic earnings per share $ 0.31 $ 0.07 $ 0.16 $ 0.06 $ 0.16 $ 0.07 $ 0.05 $ 0.17 Diluted earnings per share $ 0.31 $ 0.07 $ 0.16 $ 0.05 $ 0.16 $ 0.07 $ 0.05 $ 0.17 Weighted average common shares (basic) 23,911,419 25,066,086 23,952,443 24,575,211 23,973,116 24,129,512 24,104,239 23,919,483 Weighted average common shares (diluted) 24,275,665 25,132,441 24,346,553 24,699,794 24,510,092 24,307,540 24,795,366 24,032,613

Basis of Presentation and Con28

Basis of Presentation and Consolidation (Policies)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements include the accounts of Blue Hills Bancorp, Inc. (the “Company”), a Maryland corporation, and its wholly-owned subsidiaries, Blue Hills Funding Corporation and Blue Hills Bank ("the Bank"), the principal operating entity. The Bank's wholly-owned subsidiaries include B.H. Security Corporation, HP Security Corporation, and 1196 Corporation, which are Massachusetts security corporations. All significant intercompany balances and transactions have been eliminated in consolidation.
Use of estimates	Use of estimates In preparing consolidated financial statements in conformity with accounting principles generally accepted in the United States of America, management is required to make estimates and assumptions that affect the reported amounts of assets and liabilities as of the date of the balance sheet and reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Material estimates that are particularly susceptible to significant change in the near term relate to the determination of the allowance for loan losses and the realizability of deferred tax assets.
Cash and cash equivalents	Cash and cash equivalents For purposes of the consolidated statements of cash flows, cash and cash equivalents include cash on hand, balances due from banks, and short-term investments comprised of federal funds sold, money-market mutual funds, and interest-bearing deposits, all of which mature within ninety days. The Company maintains balances on deposit with other financial institutions in excess of the federally insured limit.
Restrictions on cash and due from banks	Restrictions on cash and due from banks The Company may be required to maintain average balances on hand or with the Federal Reserve Bank ( the “FRB”).
Fair value hierarchy	Fair value hierarchy The Company groups its assets and liabilities measured at fair value in three levels, based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. Level 1 - Valuation is based on quoted prices in active markets for identical assets or liabilities. Valuations are obtained from readily available pricing sources for market transactions involving identical assets or liabilities. Level 2 - Valuation is based on observable inputs other than Level 1 prices, such as quoted prices for similar assets and liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets and liabilities. Level 3 - Valuation is based on unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Level 3 assets and liabilities include those whose value is determined using unobservable inputs to pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation.
Securities	Securities Debt securities that management has the positive intent and ability to hold to maturity are classified as “held-to-maturity” and recorded at amortized cost. Securities not classified as held-to-maturity, including equity securities with readily determinable fair values, are classified as “available-for-sale” and recorded at fair value, with unrealized gains and losses excluded from earnings and reported in other comprehensive income. Purchase premiums and discounts are recognized in interest income using the interest method over the terms of the securities. Gains and losses on the sale of securities are recorded on the trade date and are determined using the specific identification method. At least quarterly, and more frequently when warranted by economic or market conditions, management evaluates all securities with a decline in fair value below the amortized cost of the investment to determine whether or not the impairment is deemed to be other-than-temporary ("OTTI"). OTTI is required to be recognized if: (1) the Company intends to sell the security; (2) it is more likely than not that the Company will be required to sell the security before recovery of its amortized cost basis; or (3) for debt securities, the present value of expected cash flows is not sufficient to recover the entire amortized cost basis. For all impaired debt securities that the Company intends to sell, or more likely than not will be required to sell, the full amount of the depreciation is recognized as OTTI through earnings. Credit-related OTTI for all other impaired debt securities is recognized through earnings. Non-credit related OTTI for such debt securities is recognized in other comprehensive income, net of applicable taxes. Marketable equity securities are evaluated for OTTI based on the severity and duration of the impairment and, if deemed to be other than temporary, the declines in fair value are reflected in earnings as realized losses.
Federal Home Loan Bank stock	Federal Home Loan Bank stock The Company, as a member of the Federal Home Loan Bank of Boston (the "FHLBB") system, is required to maintain an investment in capital stock of the FHLBB. Based on the redemption provisions of the FHLBB, the stock has no quoted market value and is carried at cost. At its discretion, the FHLBB may declare dividends on the stock. The Company reviews its investment for impairment based on the ultimate recoverability of the cost basis in the FHLBB stock.
Loans held for sale	Loans held for sale Loans originated and intended for sale in the secondary market are carried at the lower of cost or estimated fair value in the aggregate. Net unrealized losses, if any, are recognized through a valuation allowance by charges to income.
Loans	Loans The Company has historically granted mortgage and consumer loans to its customers and a substantial portion of the loan portfolio consists of mortgage loans in communities including and near the locations of its banking offices. The ability of the Company’s debtors to honor their contracts is dependent upon the real estate and general economic conditions in these areas. The Company’s loan portfolio includes 1-4 family residential real estate, home equity, commercial real estate, construction, commercial business, and consumer segments. Loans that management has the intent and ability to hold for the foreseeable future or until maturity or pay-off generally are reported at their outstanding unpaid principal balances adjusted for the allowance for loan losses, charge-offs, deferred origination fees and costs, and discounts and fair value adjustments on purchased loans. Interest income is accrued on the unpaid principal balance. Deferred loan origination fees/costs and discounts on purchased loans are recognized as an adjustment of the related loan yield using the interest method. It is the policy of the Company to discontinue the accrual of interest on loans past due in excess of 90 days, unless the loan is well-secured and in the process of collection, or when in the judgment of management, the ultimate collectability of the principal or interest becomes doubtful and to reverse all interest previously accrued against interest income. Past due status is based on contractual terms of the loan. The interest on non-accrual loans is accounted for on the cash-basis until qualifying for return to accrual. Loans are returned to accrual status when all the principal and interest amounts contractually due have been current for six consecutive months and future payments are reasonably assured.
Allowance for loan losses	Allowance for loan losses The allowance for loan losses is based on the size and the composition of the loan portfolio, delinquency levels, loss experience, economic conditions and other factors related to the collectability of the loan portfolio. Prior to the second quarter of 2016, for portfolios for which the Company had insufficient loss experience, losses from a national peer group of depository institutions with assets between one and five billion dollars for relevant portfolios dating back to 2009 were used. Commencing in the second quarter of 2016, the Company began to phase in its own loss history by loan type based upon the age and loss experience of the loan portfolio. This change impacted the loss factors used for the majority of loan portfolios. Loss experience is updated at least quarterly with consideration given to unique circumstances in the portfolio. Loan losses are charged against the allowance when management believes the uncollectability of a loan balance is confirmed. Subsequent recoveries, if any, are credited to the allowance. The allowance for loan losses is evaluated regularly by management and reflects consideration of all significant factors that affect the collectability of the loan portfolio. The evaluation is inherently subjective as it requires estimates that are susceptible to significant revision as more information becomes available. It is the intention of management to maintain an allowance that is prudently commensurate with the growth and risk in the loan portfolio. The allowance consists of general, allocated and unallocated components, as further described below: General component The general component of the allowance for loan losses is based on a combination of the Company's own history and an extrapolated historical loss experience based on FDIC data for depository institutions with assets of one billion to five billion dollars dating back to 2009, adjusted for qualitative and environmental factors including changes to lending policies and procedures, economic and business conditions, portfolio characteristics, staff experience, problem loan trends, collateral values, concentrations and the competitive, legal and regulatory environment. The qualitative factors are determined based on the various risk characteristics of each loan segment. Risk characteristics relevant to each portfolio segment are as follows: Residential real estate - The Company does not generally originate loans with a loan-to-value ratio greater than 80 percent and does not generally grant loans that would be classified as subprime upon origination. When the Company does extend credit either on a first- or second-lien basis at a loan-to-value ratio greater than 80 percent , such loans are supported by either mortgage insurance or state guarantee programs. All loans in this segment are collateralized by owner-occupied, 1-4 family residential real estate and repayment is dependent on the credit quality of the individual borrower. The health of the national economy, including unemployment rates and housing prices, will have an effect on the credit quality of loans in this segment. Home equity - Loans in this segment are generally secured by first or second liens on residential real estate. Repayment is dependent on the credit quality of the individual borrower. The Company evaluates each loan application based on factors including the borrower’s credit score, income, length of employment, and other factors to establish the creditworthiness of the borrower. Commercial real estate - Loans in this segment include investment real estate and are generally secured by assignments of leases, real estate collateral and owner-occupied properties. In cases where there is a concentration of exposure to a single large tenant, underwriting standards include analysis of the tenant’s ability to support lease payments over the duration of the loan. The underlying cash flows generated by the properties may be adversely impacted by a downturn in the economy due to increased vacancy rates, which in turn, can have an effect on the credit quality in this segment. Payments on loans secured by income-producing properties often depend on the successful operation and management of the properties. Management continually monitors the cash flows of these loans. Construction - Loans in this segment primarily include real estate development loans for which payment is derived from permanent financing or sale of the property. Credit risk is affected by cost overruns, time to sell at an adequate price, and market conditions. Commercial business - Loans in this segment are generally secured by business assets, including accounts receivable, inventory, real estate and intangible assets. Strict underwriting standards include considerations of the borrower’s ability to support the debt service requirements from the underlying historical and projected cash flows of the business, collateral values, the borrower’s credit history and the ultimate collectability of the debt. Economic conditions, real estate values, commodity prices, unemployment trends and other factors will affect the credit quality of loans in these segments. Consumer - Loans in this segment primarily include used classic and collector automobile loans. A significant portion of the used automobile loan portfolio is comprised of geographically diverse loans originated by and purchased from a third party, who also provides collection services. Allocated component The allocated component relates to loans that are on the watch list (partially charged-off loans, non-accruing loans and accruing adversely-rated loans) and considered impaired. Impairment is measured by either 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. An allowance is established when the discounted cash flows (or collateral value) of the impaired loan is lower than the carrying value of that loan. A loan is considered impaired when, based on current information and events, it is probable that the Company will be unable to collect the scheduled payments of principal or interest when due according to the contractual terms of the loan agreement. Management reviews all loan types for individual impairment. Factors considered by management in determining impairment include payment status, collateral value, and the probability of collecting scheduled principal and interest payments when due. Loans that experience insignificant payment delays and payment shortfalls generally are not classified as impaired. Management determines the significance of payment delays and payment shortfalls on a case-by-case basis, taking into consideration all of the circumstances surrounding the loan and the borrower, including the length of the delay, the reasons for the delay, the borrower’s prior payment record, and the amount of the shortfall in relation to the principal and interest owed. The Company periodically may agree to modify the contractual terms of loans. When a loan is modified and a concession is made to a borrower experiencing financial difficulty, the modification is considered a troubled debt restructuring (“TDR”). All TDRs are initially classified as impaired and generally remain impaired for the remaining life of the loan. The impaired classification may be removed if the borrower demonstrates compliance with the modified terms and the restructuring agreement specifies an interest rate equal to that which would be provided to a borrower with similar credit at the time of restructuring. Unallocated component Through the third quarter of 2016, the Company maintained an unallocated component to cover uncertainties that could affect management’s estimate of probable losses. The unallocated component of the allowance reflected the margin of imprecision inherent in the underlying assumptions used in the methodologies for estimating allocated and general reserves in the portfolio. As a large portion of the Company's loan portfolio had seasoned, the unallocated component of the allowance for loan losses was eliminated during the fourth quarter of 2016.
Foreclosed Assets	Foreclosed Assets Assets acquired through, or in lieu of, loan foreclosure are held for sale and are initially recorded at fair value, less cost to sell, at the date of foreclosure, establishing a new cost basis. Subsequent to foreclosure, valuations are periodically performed by management and the assets are carried at the lower of carrying amount or fair value less cost to sell. Revenue and expenses from operations, changes in the valuation allowance and any direct writedowns are included in net expenses from foreclosed assets.
Premises and equipment	Premises and equipment Land is carried at cost. Buildings, leasehold improvements and equipment are stated at cost, less accumulated depreciation and amortization, computed on the straight-line method over the estimated useful lives of the assets or the expected terms of the leases, if shorter. Expected terms include lease option periods to the extent that the exercise of such options is reasonably assured.
Goodwill and identifiable intangible assets	Goodwill and identifiable intangible assets Goodwill is the price paid in excess of the fair value of net assets acquired and is not amortized. Goodwill at December 31, 2017 and 2016 relates to the acquisition of Nantucket Bank. Goodwill is evaluated for impairment at least annually, or more often if warranted, using a combined qualitative and quantitative impairment approach.The initial qualitative approach assesses whether the existence of events or circumstances led to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If, after assessing the totality of events and circumstances, the Company determines it is more likely than not that the fair value is less than carrying value, the two-step quantitative impairment test is performed. Step one of the quantitative impairment test compares book value to the fair value of the reporting unit. If test one is failed, a more detailed analysis is performed, which involves measuring the excess of the fair value of the reporting unit, as determined in step one, over the aggregate fair value of the individual assets, liabilities, and identifiable intangibles as if the reporting unit was being acquired in a business combination. Effective January 1, 2017, the Company adopted Financial Accounting Standards Board ("FASB") Accounting Standards Update ("ASU") 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment. The amendments in this Update simplify the goodwill impairment model by eliminating the second step of the model. The resulting impairment test compares the fair value of a reporting unit with its carrying amount, including goodwill. If the carrying amount exceeds the reporting unit’s fair value, an impairment charge would be recognized for the difference, but should not exceed the carrying amount of goodwill allocated to that reporting unit. The Company still has the option to perform the qualitative assessment to determine if the quantitative impairment test is necessary. Early adoption of this Update had no impact on the Company’s consolidated financial statements. Identifiable intangible assets subject to amortization consist of the core deposit intangible acquired in the acquisition of Nantucket Bank, which has an estimated life of approximately 5.5 years. Identifiable intangible assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable. The core deposit intangible is being amortized using the sum of the years' digits method over its estimated life.
Bank-owned life insurance	Bank-owned life insurance Bank-owned life insurance policies are reflected on the consolidated balance sheets at cash surrender value. Changes in cash surrender value are reflected in noninterest income in the consolidated statements of net income.
Mortgage Servicing Rights	Mortgage Servicing Rights The Company services mortgage loans for others. Mortgage servicing assets are recognized as separate assets when rights are acquired through purchase or through sale of financial assets. Fair value is determined using prices for similar assets with similar characteristics, when available, or based upon discounted cash flows using market-based assumptions. The valuation model incorporates assumptions that market participants would use in estimating future net servicing income, such as the cost to service, the discount rate, an inflation rate, ancillary income, prepayment speeds and default rates and losses. Capitalized servicing rights are reported in other assets and are amortized into loan servicing fee income in proportion to, and over the period of, the estimated future net servicing income of the underlying financial assets. Servicing assets are evaluated for impairment based upon the fair value of the rights as compared to amortized cost. Impairment is determined by stratifying rights by predominant risk characteristics, such as interest rates and terms. Impairment is recognized through a valuation allowance for an individual stratum, to the extent that fair value is less than the capitalized amount for the stratum. Changes in the valuation allowance are reported in loan servicing fee income.
Non-marketable investments	Non-marketable investments The aggregate carrying amount of all cost and equity method investments included in other assets at December 31, 2017 and 2016 is $ 11.3 million and $ 10.2 million , respectively. The fair values of these investments are not readily available and are not evaluated for impairment unless there are identified events or changes in circumstances that may have a significant adverse effect on the fair value of the investments.
Interest rate swap agreements and Derivative Loan and Forward Loan Sale Commitments	Interest rate swap agreements For asset/liability management purposes, the Company periodically uses interest rate swap agreements to hedge various exposures or to modify interest rate characteristics of various balance sheet accounts. All interest rate swap agreements are recorded at fair value. Depending upon the intended use for the interest rate swap 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. If the interest rate swap is not designated in a hedge relationship, gains or losses reflecting changes in fair value are recorded in earnings. Certain interest rate swap contracts are utilized to help commercial loan borrowers manage their interest rate risk. The interest rate swap contracts with commercial loan borrowers allow the borrowers to convert floating rate loan payments to fixed rate payments. When the Company enters into an interest rate swap contract with a commercial loan borrower, the Company concurrently enters into a matching interest rate swap with a correspondent bank counterparty in order to minimize interest rate risk to the Company. These interest rate derivative instruments are recorded on the consolidated balance sheets as either an asset or liability measured at fair value. These derivatives do not qualify for hedge accounting. As such, all changes in fair value of these derivative instruments are included in miscellaneous income. The Company pays and receives fees for entering into these contracts. The net fees are recognized in loan level derivative income when received. Derivative Loan Commitments Mortgage loan commitments are referred to as derivative loan commitments if the loan that will result from exercise of the commitment will be held for sale upon funding. Loan commitments that are derivatives are recognized at fair value on the consolidated balance sheet in other assets and other liabilities with changes in their fair values recorded in mortgage banking income. Forward Loan Sale Commitments To protect against the price risk inherent in derivative loan commitments, the Company enters into forward loan sale commitments to mitigate the risk of potential decreases in the values of loans that would result from the exercise of the derivative loan commitments. Forward loan sale commitments are recognized at fair value on the consolidated balance sheet in other assets or other liabilities with changes in their fair values recorded in mortgage banking income. The Company estimates the fair value of its forward loan sale commitments based on changes in the fair value of underlying mortgage loans.
Transfers of financial assets	Transfers of financial assets Transfers of an entire financial asset, a group of entire financial assets, or a participating interest in an entire financial asset 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. During the normal course of business, the Company may transfer a portion of a financial asset, for example, a participation loan. In order to be eligible for sales treatment, the transfered portion of the loan must meet the criteria of a participating interest. If it does not meet the criteria of a participating interest, the transfer must be accounted for as a secured borrowing. In order to meet the criteria for a participating interest, all cash flows from the loan must be divided proportionately, the rights of each loan holder must have the same priority, the loan holders must have no recourse to the transferor other than standard representations and warranties and no loan holder has the right to pledge or exchange the entire loan.
Retirement plan	Retirement plan The Company accounts for its defined benefit pension plan using an actuarial model that allocates pension costs over the service period of employees in the plan. The Company accounts for the over-funded or under-funded status of its defined benefit plan as an asset or liability on its consolidated balance sheets and recognizes changes in the funded status that are not reflected in net periodic pension cost as other comprehensive income or loss. The Company amended its defined benefit pension plan in 2013 freezing the plan to new participants and subsequently amended the plan and froze it for all participants effective October 31, 2014.
Earnings per common share	Earnings per common share Basic earnings per share represents income available to common stockholders divided by the weighted-average number of common shares outstanding during the period. Unallocated ESOP shares are not deemed outstanding for earnings per share calculations. Dividend rights on unvested restricted stock awards are forfeitable; therefore unvested restricted stock awards are not considered outstanding in the computation of basic earnings per share. Diluted earnings per share reflects additional common shares that would have been outstanding if dilutive potential common shares had been issued, as well as any adjustment to income that would result from the assumed issuance. Potential common shares that may be issued by the Company relate to outstanding stock options and unvested restricted stock awards and are determined using the treasury stock method.
Advertising costs	Advertising costs Advertising costs are expensed as incurred.
Share-based Compensation Plans	Share-based Compensation Plans The Company measures and recognizes compensation cost relating to share-based payment transactions based on the grant-date fair value of the equity instruments issued. Share-based compensation is recognized over the period the employee is required to provide services for the award. The Company uses the Black-Scholes option-pricing model to determine the fair value of stock options granted. For an award with a performance and/or service condition that affects vesting, the performance and/or service condition is not considered in determining the award’s fair value on the grant date.
Employee Stock Ownership Plan	Employee Stock Ownership Plan Compensation expense for the 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 period. 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. Unearned compensation applicable to the ESOP is reflected as a reduction of stockholders' equity on the consolidated balance sheet. 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.
Income taxes	Income taxes Deferred tax assets and liabilities are reflected at currently enacted income tax rates applicable to the period in which the deferred tax assets or liabilities are expected to be realized or settled. As changes in tax laws or rates are enacted, deferred tax assets and liabilities are adjusted through the provision for income taxes. A ccordingly, changes resulting from the Tax Cuts and Jobs Act enacted on December 22, 2017 have been recognized in the consolidated financial statements as of and for the year ended December 31, 2017. See Note 8. The Company exercises significant judgment in evaluating the amount and timing of recognition of the resulting tax assets and liabilities. These judgments require the Company to make projections of future taxable income. These judgments and estimates, which are inherently subjective, are reviewed periodically as regulatory and business factors change. A valuation allowance related to deferred tax assets is established when, in the judgment of management, it is more likely than not that all or a portion of such deferred tax assets will not be realized. A tax position that meets the more likely than not recognition threshold is initially and subsequently measured as the largest amount of tax benefit that has a greater than 50% likelihood of being realized upon settlement with a taxing authority that has full knowledge of all relevant information. The determination of whether or not a tax position has met the more likely than not recognition threshold considers the facts, circumstances and information available at the reporting date and is subject to management’s judgment. There was no reserve for uncertain tax positions as of December 31, 2017 or 2016 . The Company records interest and penalties as part of income tax expense. Effective January 1, 2017, with the application of ASU 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting, the Company no longer records the excess tax benefits or deficiencies related to share-based compensation in additional paid in capital. Instead, excess tax benefits or deficiencies are recorded in the income statement as part of the provision for income taxes on a prospective basis. For interim reporting purposes the excess tax benefits or deficiencies are recorded as discrete items in the period in which they occur. Excess tax benefits are now presented as an operating activity in the statement of cash flows. In addition, under the new guidance, when calculating incremental shares for earnings per share, entities exclude from assumed proceeds excess tax benefits that previously would have been recorded in additional paid in capital. The total income tax benefit recorded in the provision for income taxes relating to excess tax benefits on stock-based compensation for the year ended December 31, 2017 was $448,000 . In 2016, income tax benefits related to stock compensation in excess of grant date fair value less any proceeds on exercise were recognized as an increase to additional paid-in capital upon vesting or exercising and delivery of the stock. Any income tax effects related to stock compensation that were less than grant date fair value less any proceeds on exercise were recognized as a reduction of additional paid-in capital to the extent of previously recognized income tax benefits and then through income tax expense for the remaining amount.
Comprehensive Income	Comprehensive Income/Loss Accounting principles generally require that recognized revenue, expenses, gains and losses be included in net income. Although certain changes in assets and liabilities are reported as a separate component of the equity section of the balance sheet, such items, along with net income, are components of comprehensive income/loss.
Reclassification	Reclassification Certain amounts in the 2016 consolidated financial statements have been reclassified to conform to the 2017 presentation.
Recent Accounting Standards Updates	RECENT ACCOUNTING STANDARDS UPDATES In February 2018, the FASB issued ASU 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. The purpose of this Update is to allow a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. The Update is effective for public business entities for annual periods being after December 15, 2018, and interim periods within those fiscal years. Early adoption of the amendments in this Update is permitted, including adoption in any interim period. The Company adopted the Update on January 1, 2018. The impact to the consolidated financial statements upon adopting this Update is not material. See Note 16 to the consolidated financial statements. In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging:Targeted Improvements to Accounting for Hedging Activities . The purpose of this Update is to better align a company’s financial reporting for hedging activities with the economic objectives of those activities. This Update is effective for public business entities for fiscal years beginning after December 15, 2018, with early adoption, including adoption in an interim period permitted. The Update requires a modified retrospective transition method in which the Company will recognize the cumulative effect of the change on the opening balance of each affected component of equity in the statement of financial position as of the date of adoption. While the Company continues to assess all potential impacts of the standard, we currently expect the adoption to have an immaterial impact on our consolidated financial statements. In May 2017, the FASB issued ASU 2017-09, Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting which amends the scope of modification accounting for share-based payment arrangements. The Update provides guidance on the types of changes to the terms or conditions of share-based payment awards to which an entity would be required to apply modification accounting. Specifically, an entity would not apply modification accounting if the fair value, vesting conditions, and classification of the awards are the same immediately before and after the modification. The Update is effective for public business entities for annual periods being after December 15, 2017, including interim periods within those annual periods. The Update should be applied prospectively to awards modified on or after the effective date. The impact to the consolidated financial statements upon adopting this Update is not expected to be material. In January 2016, the FASB issued ASU 2016-01, Financial Instruments – Overall, (Subtopic 825-10) . The amendments in this Update address certain aspects of recognition, measurement, presentation, and disclosure of financial instruments. Targeted improvements to generally accepted accounting principles include the requirement for equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income and the elimination of the requirement for public business entities to disclose the methods and significant assumptions used to estimate the fair value for financial instruments measured at amortized cost. For public business entities, the amendments in this Update are effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The Company does not anticipate that adoption of the Update will materially impact the Company's financial position. The Update also requires Companies to utilize an "exit price" fair value methodology when measuring the fair value of financial instruments. The impact of the change, if applied, to the Company's equity investments for the year ended December 31, 2017 would have resulted in a gain of $1.7 million (pre-tax) being recognized in net income, after reclassification for the realized loss on mutual funds. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) . This Update is intended to improve financial reporting about leasing transactions and the key provision impacting the Company is the requirement for a lessee to record a right-to-use asset and a liability representing the obligation to make lease payments for long-term operating leases. Additionally, the Update includes additional quantitative and qualitative disclosures required by lessees and lessors to help users better understand the amount, timing, and uncertainty of cash flows arising from leases. This Update is effective for fiscal years beginning after December 31, 2018, and interim periods within those fiscal years. Lessees and lessors are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. The modified retrospective approach includes a number of optional practical expedients that entities may elect to apply as well as transition guidance specific to nonstandard leasing transactions. The Company's assets and liabilities will increase based on the present value of remaining lease payments for leases in place at the adoption date; however, this is not expected to be material to the Company's results of operations or financial position. Future lease commitments as of December 31, 2017 amounted to $21.8 million . In June, 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , which removes the thresholds that companies apply to measure credit losses on financial instruments measured at amortized cost, such as loans, receivables, and held-to-maturity debt securities. Under current U.S. GAAP, companies generally recognize credit losses when it is probable that the loss has been incurred. The revised guidance will remove previously established recognition thresholds based on probability, and will require companies to recognize an allowance for credit losses for the difference between the amortized cost basis of a financial instrument and the net amount that the company expects to collect over the instrument’s contractual life. ASU 2016-13 also amends the credit loss measurement guidance for available-for-sale debt securities and will require that credit losses be recorded through an allowance for credit losses. Additionally, this Update may reduce the carrying value of the Company's held-to-maturity investment securities as it will require an allowance on the expected losses over the life of these securities to be recorded upon adoption. The ASU is effective for public business entities fiscal years beginning after December 15, 2019 and for interim periods within those fiscal years. Any increase in our allowance for loan losses or expenses may have a material adverse effect on our financial condition and results of operations. The Company is actively working through the provisions of the Update. Management has established a steering committee which has identified the methodologies and the additional data requirements necessary to implement the Update and has engaged a third-party software service provider to assist in the Company's implementation. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers . This Update 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. This Update is effective for annual periods beginning after December 15, 2017, including interim periods within that reporting period with early adoption permitted. The Company's revenue relates principally to financial instruments, which are explicitly excluded from the scope of the new guidance. Therefore the impact to the consolidated financial statements upon adopting this Update is not expected to be material. In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory . The amendments in this Update require an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. For public business entities, the amendments are effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within those annual reporting periods. The impact to the consolidated financial statements upon adopting this Update is not expected to be material. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash . The amendments in this Update require that in the statement of cash flows, amounts generally described as restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts. For public business entities, the amendments are effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The impact to the consolidated financial statements upon adopting this Update is not expected to be material.

Basis of Presentation and Con29

Basis of Presentation and Consolidation (Tables)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Finite-Lived Intangible Assets	The core deposit intangible is being amortized using the sum of the years' digits method over its estimated life. Information related to the core deposit intangible, including the estimated annual amortization expense, is summarized below: (In thousands) Balance at December 31, 2014 $ 4,232 Amortization (1,607 ) Balance at December 31, 2015 2,625 Amortization (1,225 ) Balance at December 31, 2016 1,400 Amortization (843 ) Balance at December 31, 2017 $ 557
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	Estimated amortization expense for the years ending December 31, 2018 $ 461 2019 96 Total remaining $ 557

Securities (Tables)

Securities (Tables)	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Schedule of Available-for-sale Securities Reconciliation	The amortized cost and estimated fair value of securities available for sale and held to maturity, with gross unrealized gains and losses, follow: December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (In thousands) Securities Available for Sale: Marketable equity securities $ 9,437 $ 755 $ (472 ) $ 9,720 Securities Held to Maturity: Debt securities: Government-sponsored enterprises $ 30,673 $ — $ (894 ) $ 29,779 Government-sponsored mortgage-backed and collateralized mortgage obligations 244,668 30 (3,437 ) 241,261 SBA asset-backed securities 28,375 28 (329 ) 28,074 Total securities held to maturity $ 303,716 $ 58 $ (4,660 ) $ 299,114 December 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (In thousands) Securities Available for Sale: Debt securities: Mortgage- and other asset-backed securities: Privately issued commercial mortgage-backed securities $ 10,530 $ — $ (41 ) $ 10,489 Other asset-backed securities 9,174 6 (195 ) 8,985 Total mortgage- and other asset-backed securities 19,704 6 (236 ) 19,474 State and political 12,730 120 (157 ) 12,693 Financial services: Banks 20,263 57 (298 ) 20,022 Diversified financial entities 17,198 190 (198 ) 17,190 Insurance and REITs 18,304 150 (216 ) 18,238 Total financial services 55,765 397 (712 ) 55,450 Other corporate: Industrials 49,217 508 (761 ) 48,964 Utilities 24,895 292 (100 ) 25,087 Total other corporate 74,112 800 (861 ) 74,051 Total debt securities 162,311 1,323 (1,966 ) 161,668 Marketable equity securities: Mutual funds: Domestic community 3,216 25 (19 ) 3,222 Global asset allocation 42,396 48 (2,498 ) 39,946 Total marketable equity securities 45,612 73 (2,517 ) 43,168 Total securities available for sale $ 207,923 $ 1,396 $ (4,483 ) $ 204,836 Securities Held to Maturity: Debt securities: Government-sponsored enterprises $ 32,667 $ 4 $ (934 ) $ 31,737 Government-sponsored mortgage-backed and collateralized mortgage obligations 153,938 14 (1,806 ) 152,146 SBA asset-backed securities 14,422 — (212 ) 14,210 Total securities held to maturity $ 201,027 $ 18 $ (2,952 ) $ 198,093
Schedule of Held-to-maturity Securities Reconciliation	The amortized cost and estimated fair value of securities available for sale and held to maturity, with gross unrealized gains and losses, follow: December 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (In thousands) Securities Available for Sale: Marketable equity securities $ 9,437 $ 755 $ (472 ) $ 9,720 Securities Held to Maturity: Debt securities: Government-sponsored enterprises $ 30,673 $ — $ (894 ) $ 29,779 Government-sponsored mortgage-backed and collateralized mortgage obligations 244,668 30 (3,437 ) 241,261 SBA asset-backed securities 28,375 28 (329 ) 28,074 Total securities held to maturity $ 303,716 $ 58 $ (4,660 ) $ 299,114 December 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (In thousands) Securities Available for Sale: Debt securities: Mortgage- and other asset-backed securities: Privately issued commercial mortgage-backed securities $ 10,530 $ — $ (41 ) $ 10,489 Other asset-backed securities 9,174 6 (195 ) 8,985 Total mortgage- and other asset-backed securities 19,704 6 (236 ) 19,474 State and political 12,730 120 (157 ) 12,693 Financial services: Banks 20,263 57 (298 ) 20,022 Diversified financial entities 17,198 190 (198 ) 17,190 Insurance and REITs 18,304 150 (216 ) 18,238 Total financial services 55,765 397 (712 ) 55,450 Other corporate: Industrials 49,217 508 (761 ) 48,964 Utilities 24,895 292 (100 ) 25,087 Total other corporate 74,112 800 (861 ) 74,051 Total debt securities 162,311 1,323 (1,966 ) 161,668 Marketable equity securities: Mutual funds: Domestic community 3,216 25 (19 ) 3,222 Global asset allocation 42,396 48 (2,498 ) 39,946 Total marketable equity securities 45,612 73 (2,517 ) 43,168 Total securities available for sale $ 207,923 $ 1,396 $ (4,483 ) $ 204,836 Securities Held to Maturity: Debt securities: Government-sponsored enterprises $ 32,667 $ 4 $ (934 ) $ 31,737 Government-sponsored mortgage-backed and collateralized mortgage obligations 153,938 14 (1,806 ) 152,146 SBA asset-backed securities 14,422 — (212 ) 14,210 Total securities held to maturity $ 201,027 $ 18 $ (2,952 ) $ 198,093
Investments Classified by Contractual Maturity Date	The amortized cost and estimated fair value of debt securities by contractual maturity at December 31, 2017 follow. Expected maturities will differ from contractual maturities because the issuers may have the right to call or prepay obligations with or without call or prepayment penalties. Based on expected maturities, the mortgage and asset-backed securities and collateralized mortgage obligations, included below, have a 3.9 year weighted average duration. Held to Maturity Amortized Cost Fair Value (In thousands) After 1 year through 5 years $ 15,626 $ 15,366 After 5 years through 10 years 15,047 14,413 30,673 29,779 Mortgage- and asset-backed securities and collateralized mortgage obligations amortizing monthly 273,043 269,335 Total debt securities $ 303,716 $ 299,114
Available-for-sale Securities	Information pertaining to securities with gross unrealized losses aggregated by investment category and length of time that individual securities have been in a continuous loss position, follows: December 31, 2017 Less Than Twelve Months More Than Twelve Months Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value (In thousands) Securities Available for Sale: Temporarily impaired marketable equity securities $ (449 ) $ 4,310 $ (23 ) $ 443 Securities Held to Maturity: Debt securities: Government-sponsored enterprises $ (109 ) $ 8,521 $ (785 ) $ 21,258 Government-sponsored mortgage-backed and collateralized mortgage obligations (1,563 ) 119,782 (1,874 ) 111,712 SBA asset-backed securities (34 ) 9,897 (295 ) 11,423 Total temporarily impaired securities held to maturity $ (1,706 ) $ 138,200 $ (2,954 ) $ 144,393 December 31, 2016 Less Than Twelve Months More Than Twelve Months Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value (In thousands) Securities Available for Sale: Debt securities: Mortgage- and other asset-backed securities: Privately issued commercial mortgage- backed securities $ (11 ) $ 3,163 $ (30 ) $ 7,326 Other asset-backed securities (43 ) 3,924 (152 ) 3,732 Total mortgage- and other asset-backed securities (54 ) 7,087 (182 ) 11,058 State and political (157 ) 5,301 — — Financial services: Banks (298 ) 14,553 — — Diversified financial entities (198 ) 9,369 — — Insurance and REITs (216 ) 6,900 — — Total financial services (712 ) 30,822 — — Other corporate: Industrials (655 ) 24,630 (106 ) 2,284 Utilities (99 ) 11,200 (1 ) 794 Total other corporate (754 ) 35,830 (107 ) 3,078 Total debt securities (1,677 ) 79,040 (289 ) 14,136 Marketable equity securities: Mutual funds: Domestic community — — (19 ) 448 Global asset allocation (424 ) 15,153 (2,074 ) 22,442 Total marketable equity securities (424 ) 15,153 (2,093 ) 22,890 Total temporarily impaired securities available for sale $ (2,101 ) $ 94,193 $ (2,382 ) $ 37,026 Securities Held to Maturity: Debt securities: Government-sponsored enterprises $ (934 ) $ 28,533 $ — $ — Government-sponsored mortgage-backed and collateralized mortgage obligations (1,763 ) 146,098 (43 ) 3,827 SBA asset-backed securities (104 ) 9,157 (108 ) 5,053 Total temporarily impaired securities held to maturity $ (2,801 ) $ 183,788 $ (151 ) $ 8,880
Held-to-maturity Securities	Information pertaining to securities with gross unrealized losses aggregated by investment category and length of time that individual securities have been in a continuous loss position, follows: December 31, 2017 Less Than Twelve Months More Than Twelve Months Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value (In thousands) Securities Available for Sale: Temporarily impaired marketable equity securities $ (449 ) $ 4,310 $ (23 ) $ 443 Securities Held to Maturity: Debt securities: Government-sponsored enterprises $ (109 ) $ 8,521 $ (785 ) $ 21,258 Government-sponsored mortgage-backed and collateralized mortgage obligations (1,563 ) 119,782 (1,874 ) 111,712 SBA asset-backed securities (34 ) 9,897 (295 ) 11,423 Total temporarily impaired securities held to maturity $ (1,706 ) $ 138,200 $ (2,954 ) $ 144,393 December 31, 2016 Less Than Twelve Months More Than Twelve Months Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value (In thousands) Securities Available for Sale: Debt securities: Mortgage- and other asset-backed securities: Privately issued commercial mortgage- backed securities $ (11 ) $ 3,163 $ (30 ) $ 7,326 Other asset-backed securities (43 ) 3,924 (152 ) 3,732 Total mortgage- and other asset-backed securities (54 ) 7,087 (182 ) 11,058 State and political (157 ) 5,301 — — Financial services: Banks (298 ) 14,553 — — Diversified financial entities (198 ) 9,369 — — Insurance and REITs (216 ) 6,900 — — Total financial services (712 ) 30,822 — — Other corporate: Industrials (655 ) 24,630 (106 ) 2,284 Utilities (99 ) 11,200 (1 ) 794 Total other corporate (754 ) 35,830 (107 ) 3,078 Total debt securities (1,677 ) 79,040 (289 ) 14,136 Marketable equity securities: Mutual funds: Domestic community — — (19 ) 448 Global asset allocation (424 ) 15,153 (2,074 ) 22,442 Total marketable equity securities (424 ) 15,153 (2,093 ) 22,890 Total temporarily impaired securities available for sale $ (2,101 ) $ 94,193 $ (2,382 ) $ 37,026 Securities Held to Maturity: Debt securities: Government-sponsored enterprises $ (934 ) $ 28,533 $ — $ — Government-sponsored mortgage-backed and collateralized mortgage obligations (1,763 ) 146,098 (43 ) 3,827 SBA asset-backed securities (104 ) 9,157 (108 ) 5,053 Total temporarily impaired securities held to maturity $ (2,801 ) $ 183,788 $ (151 ) $ 8,880

Loans and The Allowance for L31

Loans and The Allowance for Loan Losses (Tables)	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Schedule of Accounts, Notes, Loans and Financing Receivable	A summary of the balances of loans follows: December 31, 2017 2016 (In thousands) Real estate: 1-4 family residential $ 922,627 $ 851,154 Home equity 80,662 78,719 Commercial real estate 834,264 687,289 Construction 91,050 76,351 1,928,603 1,693,513 Commercial business 253,509 206,234 Consumer 21,698 29,281 Total loans 2,203,810 1,929,028 Allowance for loan losses (20,877 ) (18,750 ) Discount and fair value adjustments on purchased loans (1,477 ) (1,846 ) Deferred loan costs and fees, net 4,691 4,439 Loans, net $ 2,186,147 $ 1,912,871
Activity in Allowance for Loan Losses	Activity in the allowance for loan losses for the years ended December 31, 2017 , 2016 and 2015 follows: 1-4 Family Home Commercial Construction Commercial Consumer Unallocated Total (In thousands) 2017 Beginning balance $ 4,846 $ 537 $ 8,374 $ 1,353 $ 3,206 $ 434 $ — $ 18,750 Provision for loan losses 83 162 1,283 355 193 22 — 2,098 Loans charged-off (52 ) — (73 ) — — (134 ) — (259 ) Recoveries 199 — — — 74 15 — 288 Ending balance $ 5,076 $ 699 $ 9,584 $ 1,708 $ 3,473 $ 337 $ — $ 20,877 2016 Beginning balance $ 3,916 $ 636 $ 7,147 $ 1,364 $ 2,839 $ 772 $ 428 $ 17,102 Provision (credit) for loan losses 830 (99 ) 1,447 (11 ) 3,428 (282 ) (428 ) 4,885 Loans charged-off — — (321 ) — (3,098 ) (56 ) — (3,475 ) Recoveries 100 — 101 — 37 — — 238 Ending balance $ 4,846 $ 537 $ 8,374 $ 1,353 $ 3,206 $ 434 $ — $ 18,750 2015 Beginning balance $ 3,222 $ 340 $ 3,551 $ 1,056 $ 3,410 $ 736 $ 658 $ 12,973 Provision (credit) for loan losses 612 296 3,596 308 (571 ) 79 (230 ) 4,090 Loans charged-off — — — — — (43 ) — (43 ) Recoveries 82 — — — — — — 82 Ending balance $ 3,916 $ 636 $ 7,147 $ 1,364 $ 2,839 $ 772 $ 428 $ 17,102
Allowance for Credit Losses on Financing Receivables	Additional information pertaining to the allocation of the allowance for loan losses to loan segments at December 31, 2017 and 2016 , follows: 1-4 Family Home Commercial Construction Commercial Consumer Unallocated Total (In thousands) December 31, 2017 Allowance related to impaired loans $ 80 $ — $ — $ — $ — $ 1 $ — $ 81 Allowance related to non-impaired loans 4,996 699 9,584 1,708 3,473 336 — 20,796 Total allowance for loan losses $ 5,076 $ 699 $ 9,584 $ 1,708 $ 3,473 $ 337 $ — $ 20,877 Impaired loans $ 5,949 $ 1,387 $ 4,744 $ — $ — $ 202 $ — $ 12,282 Non-impaired loans 916,678 79,275 829,520 91,050 253,509 21,496 — 2,191,528 Total loans $ 922,627 $ 80,662 $ 834,264 $ 91,050 $ 253,509 $ 21,698 $ — $ 2,203,810 December 31, 2016 Allowance related to impaired loans $ 17 $ — $ — $ — $ — $ — $ — $ 17 Allowance related to non-impaired loans 4,829 537 8,374 1,353 3,206 434 — 18,733 Total allowance for loan losses $ 4,846 $ 537 $ 8,374 $ 1,353 $ 3,206 $ 434 $ — $ 18,750 Impaired loans $ 6,726 $ 1,153 $ 941 $ — $ 241 $ 170 $ — $ 9,231 Non-impaired loans 844,428 77,566 686,348 76,351 205,993 29,111 — 1,919,797 Total loans $ 851,154 $ 78,719 $ 687,289 $ 76,351 $ 206,234 $ 29,281 $ — $ 1,929,028
Past Due Financing Receivables	The following is a summary of past due and non-accrual loans, by loan segment, at December 31, 2017 and 2016 : 30-59 Days Past Due 60-89 Days Past Due Past Due 90 Days or More Total Past Due Loans on Non-accrual (In thousands) December 31, 2017 Real estate: 1-4 family residential $ 381 $ 348 $ 2,184 $ 2,913 $ 5,190 Home equity 509 13 656 1,178 1,387 Commercial real estate — — 3,893 3,893 4,744 Consumer 107 7 92 206 202 Total $ 997 $ 368 $ 6,825 $ 8,190 $ 11,523 December 31, 2016 Real estate: 1-4 family residential $ 584 $ 373 $ 2,322 $ 3,279 $ 6,478 Home equity 452 496 775 1,723 1,153 Commercial real estate 1,393 — — 1,393 941 Commercial business 4,996 13 — 5,009 241 Consumer 175 5 7 187 170 Total $ 7,600 $ 887 $ 3,104 $ 11,591 $ 8,983
Impaired Financing Receivables	The following tables set forth information regarding average balances and interest income recognized (the majority of which is on a cash basis) on impaired loans, by segment, for the years ended December 31, 2017 , 2016 and 2015 : Average Recorded Investment Interest Income Recognized 2017 (In thousands) Real estate: 1-4 family residential $ 6,254 $ 281 Home equity 1,264 58 Commercial real estate 4,125 220 Commercial business 129 20 Consumer 241 9 Total $ 12,013 $ 588 2016 Real estate: 1-4 family residential $ 6,451 $ 449 Home equity 555 29 Commercial real estate 3,192 206 Commercial business 672 55 Consumer 160 12 Total $ 11,030 $ 751 2015 Real estate: 1-4 family residential $ 4,869 $ 270 Home equity 575 14 Commercial real estate 926 161 Commercial business 2 1 Consumer 78 6 Total $ 6,450 $ 452 The following is a summary of information pertaining to impaired loans by loan segment at the dates indicated: Recorded Investment Unpaid Principal Balance Related Allowance December 31, 2017 (In thousands) Impaired loans without a valuation allowance: Real estate: 1-4 family residential $ 4,501 $ 4,897 $ — Home equity 1,387 1,523 — Commercial real estate 4,744 5,206 — Commercial business — 11 — Consumer 191 243 — Total 10,823 11,880 — Impaired loans with a valuation allowance: Real estate: 1-4 family residential 1,448 1,448 80 Consumer 11 11 1 Total 1,459 1,459 81 Total impaired loans $ 12,282 $ 13,339 $ 81 December 31, 2016 Impaired loans without a valuation allowance: Real estate: 1-4 family residential $ 6,605 $ 7,023 $ — Home equity 1,153 1,225 — Commercial real estate 941 1,207 — Commercial business 241 3,279 — Consumer 170 183 — Total 9,110 12,917 — Impaired loans with a valuation allowance: 1-4 family residential 121 313 17 Total impaired loans $ 9,231 $ 13,230 $ 17
Financing Receivable Credit Quality Indicators	The following tables present the Company’s loans by risk rating at December 31, 2017 and 2016 : 1-4 Family Residential Home Equity Commercial Real Estate Construction Commercial Business Consumer Total Loans (In thousands) December 31, 2017 Loans rated 1 - 6 $ 1,022 $ 270 $ 821,815 $ 91,050 $ 252,765 $ 3 $ 1,166,925 Loans rated 7 2,848 1,523 4,660 — 744 121 9,896 Loans rated 8 2,566 — 7,789 — — — 10,355 Loans rated 9 250 — — — — — 250 Loans rated 10 — — — — — — — Loans not rated 915,941 78,869 — — — 21,574 1,016,384 $ 922,627 $ 80,662 $ 834,264 $ 91,050 $ 253,509 $ 21,698 $ 2,203,810 December 31, 2016 Loans rated 1 - 6 $ 1,054 $ 293 $ 671,872 $ 76,351 $ 188,706 $ 4 $ 938,280 Loans rated 7 3,514 967 9,720 — 17,510 146 31,857 Loans rated 8 2,442 258 5,697 — 18 37 8,452 Loans rated 9 645 — — — — — 645 Loans rated 10 — — — — — — — Loans not rated 843,499 77,201 — — — 29,094 949,794 $ 851,154 $ 78,719 $ 687,289 $ 76,351 $ 206,234 $ 29,281 $ 1,929,028

Premises and Equipment (Tables)

Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Premises and Equipment	A summary of the cost and accumulated depreciation and amortization of premises and equipment follows: December 31, Estimated Useful Lives 2017 2016 (In thousands) Land $ 4,087 $ 4,087 Buildings 11,043 10,322 5 to 40 years Leasehold improvements 9,551 9,334 5 to 10 years Furniture and fixtures 4,139 3,874 3 to 5 years Technology equipment 6,579 6,139 1 to 3 years Construction in progress 185 169 Premises and equipment, gross 35,584 33,925 Less accumulated depreciation and amortization (14,011 ) (11,891 ) Premises and equipment, net $ 21,573 $ 22,034

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2017
Banking and Thrift [Abstract]
Schedule of Deposit Balances	A summary of deposit balances, by type, is as follows: December 31, 2017 2016 (In thousands) NOW and demand $ 381,316 $ 331,508 Regular savings 221,004 262,984 Money market 646,603 573,204 Brokered money market 92,798 53,357 Total non-certificate accounts 1,341,721 1,221,053 Term certificates of $250,000 or more 134,649 77,550 Term certificates less than $250,000 313,733 262,564 Brokered certificates of deposit 249,766 247,520 Total certificate accounts 698,148 587,634 Total deposits $ 2,039,869 $ 1,808,687
Schedule of Contractual Maturities of Deposits and Weighted Average Rate	At December 31, 2017 , the scheduled maturities of certificate accounts, including brokered certificates of deposits, are as follows: Amount Weighted Average Rate (Dollars in thousands) 2018 406,362 1.18 % 2019 180,672 1.72 2020 62,733 1.79 2021 19,513 1.84 2022 28,868 2.04 $ 698,148 1.43 %

Borrowings (Tables)

Borrowings (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Schedule of Maturities of Long-term Debt	Long-term debt consists of the following FHLBB advances: December 31, 2017 December 31, 2016 Amount Weighted Average Rate Amount Weighted Average Rate (Dollars in thousands) Fixed-rate advances maturing: 2017 $ — — % $ 15,000 1.99 % 2018 25,000 1.97 20,000 2.12 2019 35,000 1.32 25,000 1.20 2020 35,000 1.70 15,000 1.49 2021 — — 30,000 0.28 2022 * 10,000 0.42 — — $ 105,000 1.51 % $ 105,000 1.27 % * Includes advances callable in 2018

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit)	Allocation of federal and state income taxes between current and deferred portions is as follows: Years Ended December 31, 2017 2016 2015 (In thousands) Current tax provision: Federal $ 6,984 $ 3,617 $ 2,933 State 1,551 306 206 8,535 3,923 3,139 Deferred tax provision (benefit): Federal 1,792 344 7 State 77 47 (148 ) Statutory rate change 2,500 (289 ) — Federal and State 4,369 102 (141 ) Change in valuation reserve (1,678 ) (220 ) (161 ) Deferred income tax provision (benefit) 2,691 (118 ) (302 ) Provision for income taxes $ 11,226 $ 3,805 $ 2,837
Schedule of Effective Income Tax Rate Reconciliation	The reasons for the differences between the statutory federal income tax provision and the actual tax provision (benefit) are summarized as follows: Years Ended December 31, 2017 2016 2015 (Dollars in thousands) Statutory federal tax provision $ 9,700 $ 4,236 $ 3,429 Increase (decrease) resulting from: State taxes, net of federal tax benefit 1,058 233 39 Dividends received deduction (26 ) (41 ) (211 ) Tax-exempt bank-owned life insurance (372 ) (528 ) (351 ) Tax-exempt interest (155 ) (189 ) (222 ) Change in valuation reserve (1,678 ) (220 ) (161 ) Equity incentives 121 339 52 Amortization of low income housing partnership 166 219 — Tax credits utilized (188 ) (286 ) (45 ) Accrual adjustment 23 207 13 Statutory rate change 2,500 (289 ) — Other, net 77 124 294 Tax provision $ 11,226 $ 3,805 $ 2,837 Effective tax rates 40.5 % 30.5 % 28.2 %
Schedule of Deferred Tax Assets and Liabilities	The components of the net deferred tax asset are as follows: December 31, 2017 2016 (In thousands) Deferred tax assets: Federal $ 6,742 $ 11,700 State 3,416 3,258 Deferred tax assets, gross 10,158 14,958 Valuation reserve (112 ) (1,790 ) Deferred tax assets, net 10,046 13,168 Deferred tax liabilities: Federal (3,050 ) (2,427 ) State (996 ) (595 ) Deferred tax liabilities (4,046 ) (3,022 ) Net deferred tax asset $ 6,000 $ 10,146 The tax effects of each item that give rise to deferred tax assets (liabilities) are as follows: December 31, 2017 2016 (In thousands) Deferred tax assets: Depreciation and amortization $ 279 $ 747 Employee benefit plans and share-based compensation plans 410 571 Allowance for loan losses 5,868 7,660 Contribution carryover 1,122 2,317 Net unrealized loss on securities held as, or transferred, from available for sale — 893 Net unrealized losses on defined benefit pension plan 757 1,270 Deferred rent expense 170 123 Other (31 ) — Valuation reserve (112 ) (1,790 ) Deferred tax liabilities: Deferred loan origination costs (1,338 ) (1,947 ) Net unrealized gain on securities held as, or transferred from, available for sale (166 ) — Gain on exchange of investment in Northeast Retirement Services (959 ) — Other — 302 Net deferred tax asset $ 6,000 $ 10,146 A summary of the change in the net deferred tax asset is as follows: Years Ended December 31, 2017 2016 2015 (In thousands) Balance at beginning of year $ 10,146 $ 10,665 $ 6,233 Deferred tax (provision) benefit (2,691 ) 118 302 Tax effect of changes in accumulated other comprehensive income (1,455 ) (637 ) 4,130 Balance at end of year $ 6,000 $ 10,146 $ 10,665

Equity (Tables)

Equity (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations	The Company’s and the Bank’s actual capital amounts and ratios as of December 31, 2017 and 2016 are also presented in the following table. Actual Minimum Capital Requirement Minimum To Be Well Capitalized Amount Ratio Amount Ratio Amount Ratio (Dollars in thousands) Blue Hills Bancorp, Inc.: December 31, 2017 Total capital (to risk weighted assets) $ 410,088 19.7 % $ 166,635 8.0 % $ 208,294 10.0 % Tier 1 capital (to risk weighted assets) 389,211 18.7 124,977 6.0 166,635 8.0 Common equity Tier 1 (to risk weighted assets) 389,211 18.7 93,732 4.5 135,391 6.5 Tier 1 capital (to average assets) 389,211 14.9 104,278 4.0 130,348 5.0 December 31, 2016 Total capital (to risk weighted assets) 395,325 20.5 154,471 8.0 193,089 10.0 Tier 1 capital (to risk weighted assets) 376,575 19.5 115,854 6.0 154,471 8.0 Common equity Tier 1 (to risk weighted assets) 376,575 19.5 86,890 4.5 125,508 6.5 Tier 1 capital (to average assets) 376,575 16.0 94,166 4.0 117,708 5.0 Blue Hills Bank: December 31, 2017 Total capital (to risk weighted assets) 341,175 16.4 166,391 8.0 207,988 10.0 Tier 1 capital (to risk weighted assets) 320,298 15.4 124,793 6.0 166,391 8.0 Common equity Tier 1 (to risk weighted assets) 320,298 15.4 93,595 4.5 135,192 6.5 Tier 1 capital (to average assets) 320,298 12.3 104,137 4.0 130,171 5.0 December 31, 2016 Total capital (to risk weighted assets) 313,457 16.3 154,196 8.0 192,745 10.0 Tier 1 capital (to risk weighted assets) 294,707 15.3 115,647 6.0 154,196 8.0 Common equity Tier 1 (to risk weighted assets) 294,707 15.3 86,735 4.5 125,284 6.5 Tier 1 capital (to average assets) 294,707 12.5 94,099 4.0 117,623 5.0

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan	Information pertaining to the Plan is as follows: Years Ended December 31, 2017 2016 2015 (In thousands) Change in plan assets: Fair value of plan assets at beginning of year $ 9,811 $ 8,814 $ 9,443 Actual return (loss) on plan assets 1,414 847 (304 ) Employer contribution 1,110 470 — Benefits paid (178 ) (320 ) (325 ) Settlement payments (1,394 ) — — Fair value of plan assets at end of year 10,763 9,811 8,814 Change in benefit obligation: Benefit obligation at beginning of year 11,896 10,772 10,135 Interest cost 390 422 401 Actuarial loss 481 1,022 561 Benefits paid (178 ) (320 ) (325 ) Settlement payments (1,394 ) — — Benefit obligation at end of year 11,195 11,896 10,772 Funded status and accrued liability at end of year $ (432 ) $ (2,085 ) $ (1,958 ) Accumulated benefit obligation at end of year $ 11,195 $ 11,896 $ 10,772
Schedule of Assumptions Used	The assumptions used to determine net periodic pension cost (benefit) are as follows: Years Ended December 31, 2017 2016 2015 Discount rate 3.86 % 4.01 % 4.00 % Expected long-term rate of return on plan assets 8.00 % 8.00 % 8.00 %
Schedule of Net Benefit Costs	The components of net periodic pension cost (benefit) are as follows: Years Ended December 31, 2017 2016 2015 (In thousands) Interest cost 390 422 401 Expected return on plan assets (758 ) (720 ) (745 ) Amortization of net actuarial loss 297 271 110 Settlement loss 317 — — Net periodic pension cost (benefit) $ 246 $ (27 ) $ (234 )
Schedule of Allocation of Plan Assets	The fair value of major categories of the Company’s pension plan assets are summarized below: Level 1 Level 2 Level 3 Total Fair Value (In thousands) December 31, 2017 Collective funds $ 420 $ — $ — $ 420 Equity securities 2,413 — — 2,413 Mutual funds 2,079 — — 2,079 Total investments measured in the fair value hierarchy 4,912 — — 4,912 Investments measured at net asset value (a) — — — 5,851 $ 4,912 $ — $ — $ 10,763 December 31, 2016 Collective funds $ 681 $ — $ — $ 681 Equity securities 1,929 — — 1,929 Mutual funds 1,209 — — 1,209 Short-term investments 124 — — 124 $ 3,943 $ — $ — $ 3,943 Investments measured at net asset value (a) — — — 5,868 $ 3,943 $ — $ — $ 9,811 (a) In accordance with FASB ASC 820, Fair Value Measurements , certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy. There are no unfunded commitments or redemption restrictions for these investments, which can be redeemed on a daily basis.
Schedule of Expected Benefit Payments	Estimated future benefit payments, assuming employees retire at age 65 and take normal distribution payments, are as follows: Amount Year Ending December 31, (In thousands) 2018 $ 843 2019 505 2020 684 2021 933 2022 628 2023-2027 2,880
Employee Stock Ownership Plan (ESOP) Disclosures	December 31, 2017 2016 Allocated 219,860 149,613 Committed to be allocated 75,912 75,912 Unallocated 1,973,699 2,049,608 2,269,471 2,275,133

Stock Based Compensation (Table

Stock Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	The Company made the following awards of options to purchase shares of common stock during the years ended December 31, 2017 , 2016 and 2015 : 2017 2016 2015 Options granted 412,100 55,000 2,434,000 Vesting period (years) 5 5 5 Term (years) 10 10 10 Fair value calculation assumptions: Expected volatility 26.91%-27.43% 28.47 % 28.85 % Expected life (years) 6.5 6.5 6.5 Expected dividend yield 0.71%-2.22% 0.58 % 0.54 % Risk free interest rate 1.87%-2.16% 1.38 % 1.55 % Fair value per option $4.07-$5.31 $ 4.02 $ 4.23 Weighted average grant date fair value $ 5.09 $ 4.02 $ 4.23
Schedule of Share-based Compensation, Stock Options, Activity	A summary of the status of the Company's stock option grants for the year ended December 31, 2017 is presented in the table below: Stock Option Awards Weighted Average Exercise Price Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value Balance at January 1, 2017 2,449,670 $ 14.06 Granted 412,100 18.22 Forfeited (159,650 ) 14.18 Exercised (17,470 ) 13.9 — $ 77,000 Outstanding at December 31, 2017 2,684,650 $ 14.70 7.98 $ 14,506,000 Exercisable at December 31, 2017 925,990 $ 14.07 7.75 $ 5,584,000 Unrecognized compensation cost inclusive of directors' options at December 31, 2017 $6,950,000 Weighted average remaining recognition period (years) 3.12
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	The following table presents the activity in non-vested stock awards under the Equity Plan for the year ended December 31, 2017 : Outstanding Restricted Stock Awards Weighted Average Grant Price Non-vested stock awards at January 1, 2017 816,070 $ 14.06 Granted 184,695 18.25 Vested (185,028 ) 14.06 Forfeited (85,317 ) 14.11 Non-vested stock awards at December 31, 2017 730,420 $ 15.11 Unrecognized compensation cost inclusive of directors' awards at December 31, 2017 $ 9,704,000 Weighted average remaining recognition period (years) 3.17

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	Earnings per share consisted of the following components for the years ended December 31, 2017 , 2016 and 2015 . 2017 2016 2015 (Dollars in thousands, except per share amounts) Net income applicable to common stock $ 16,489 $ 8,653 $ 7,227 Average number of common shares outstanding 26,849,253 27,464,996 28,460,077 Less: Average unvested restricted stock awards (851,779 ) (957,364 ) (231,652 ) Less: Average unallocated ESOP shares (2,011,652 ) (2,087,227 ) (2,163,478 ) Average number of common shares outstanding used to calculate basic earnings per common share 23,985,822 24,420,405 26,064,947 Effect of dilutive stock options 248,161 — — Effect of dilutive unvested restricted stock awards 248,431 120,524 4,642 Average number of common shares outstanding used to calculate diluted earnings per common share 24,482,414 24,540,929 26,069,589 Earnings per common share: Basic $ 0.69 $ 0.35 $ 0.28 Diluted $ 0.67 $ 0.35 $ 0.28

Other Commitments and Conting40

Other Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of Fair Value, Off-balance Sheet Risks	Financial instruments whose contract amounts represent credit risk consist of: December 31, 2017 2016 (In thousands) Commitments to originate loans $ 66,020 $ 51,622 Letters of credit 6,314 3,277 Unused lines-of-credit: Commercial 203,631 164,185 Home equity 73,369 55,344 Consumer 15,819 15,995 Undisbursed construction loans 82,177 96,169
Schedule of Future Minimum Rental Payments for Operating Leases	Pursuant to the terms of noncancelable lease agreements in effect at December 31, 2017 , pertaining to premises, future minimum rent commitments are as follows: Year Ending December 31, Amount (In thousands) 2018 $ 2,698 2019 2,490 2020 2,409 2021 2,278 2022 2,286 Thereafter 9,640 $ 21,801

On Balance Sheet Derivative I41

On Balance Sheet Derivative Instruments and Hedging Activities (Tables)	12 Months Ended
	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Interest Rate Derivatives	The table below presents information about derivative financial instruments not designated as hedging instruments at December 31, 2017 and 2016 . Derivative Gains Derivative Losses Notional Amount Fair Value Notional Amount Fair Value (In thousands) December 31, 2017 Commercial loan level interest rate swap agreements $ 582,388 $ 8,741 $ 582,388 $ 8,741 Other contracts 27,689 25 54,293 44 Total derivatives $ 610,077 $ 8,766 $ 636,681 $ 8,785 December 31, 2016 Commercial loan level interest rate swap agreements $ 419,488 $ 9,016 $ 419,488 $ 8,932 Other contracts 15,865 8 33,045 56 Total derivatives $ 435,353 $ 9,024 $ 452,533 $ 8,988
Summary of Fair Value and Location of Mortgage Loand and Forward Loan Sale Commitments	The fair value of such commitments as of December 31, 2017 and 2016 are outlined below: Assets Liabilities Balance Sheet Location Fair Value Balance Sheet Location Fair Value (In thousands) December 31, 2017 Mortgage loan commitments Other Assets $ 210 Other Liabilities $ 36 Forward loan sale commitments Other Assets 22 Other Liabilities 69 Total $ 232 $ 105 December 31, 2016 Mortgage loan commitments Other Assets $ 111 Other Liabilities $ 3 Forward loan sale commitments Other Assets 15 Other Liabilities 74 Total $ 126 $ 77

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	Assets and liabilities measured at fair value on a recurring basis are summarized below: Level 1 Level 2 Level 3 Total Fair Value (In thousands) December 31, 2017 Assets Marketable equity securities $ 9,720 $ — $ — $ 9,720 Derivative assets: Interest rate swap agreements — 8,766 — 8,766 Forward loan sale commitments — — 22 22 Mortgage loan commitments — — 210 210 Total assets $ 9,720 $ 8,766 $ 232 $ 18,718 Liabilities Derivative liabilities: Interest rate swap agreements $ — $ 8,785 $ — $ 8,785 Forward loan sale commitments — — 69 69 Mortgage loan commitments — — 36 36 Total liabilities $ — $ 8,785 $ 105 $ 8,890 December 31, 2016 Assets Securities available for sale: Debt securities $ — $ 161,668 $ — $ 161,668 Marketable equity securities 43,168 — — 43,168 Derivative assets: Interest rate swap agreements — 9,024 — 9,024 Forward loan sale commitments — — 15 15 Mortgage loan commitments — — 111 111 Total assets $ 43,168 $ 170,692 $ 126 $ 213,986 Liabilities Derivative liabilities: Interest rate swap agreements $ — $ 8,988 $ — $ 8,988 Forward loan sale commitments — — 74 74 Mortgage loan commitments — — 3 3 Total liabilities $ — $ 8,988 $ 77 $ 9,065
Fair Value Measurements, Nonrecurring	The following table summarizes the fair value hierarchy applicable to assets measured at fair value on a non-recurring basis: December 31, 2017 December 31, 2016 Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 (In thousands) Impaired loans $ — $ — $ 2,214 $ — $ — $ 136 The following table summarizes the total losses on assets measured at fair value on a non-recurring basis for the years ended December 31, 2017 , 2016 and 2015 . Years Ended December 31, 2017 2016 2015 (In thousands) Impaired loans $ (5 ) $ (2,911 ) $ (404 )
Fair Value, by Balance Sheet Grouping	The estimated fair values, and related carrying amounts, of the Company’s financial instruments are as follows. Certain financial instruments and all nonfinancial instruments are exempt from disclosure requirements. Accordingly, the aggregate fair value amounts presented herein do not represent the underlying fair value of the Company. Carrying Fair Value Level 1 Level 2 Level 3 Total (In thousands) December 31, 2017 Financial assets: Cash and cash equivalents $ 46,167 $ 46,167 $ — $ — $ 46,167 Securities available for sale 9,720 9,720 — — 9,720 Securities held to maturity 303,716 — 299,114 — 299,114 Federal Home Loan Bank stock 12,105 — — 12,105 12,105 Loans and loans held for sale, net 2,195,139 — — 2,174,871 2,174,871 Accrued interest receivable 6,438 — — 6,438 6,438 Financial liabilities: Deposits 2,039,869 — — 2,036,150 2,036,150 Borrowings 205,000 — 203,913 — 203,913 On-balance sheet derivative financial instruments: Derivative assets: Interest rate swap agreements 8,766 — 8,766 — 8,766 Forward loan sale commitments 22 — — 22 22 Mortgage loan commitments 210 — — 210 210 Derivative liabilities: Interest rate swap agreements: 8,785 — 8,785 — 8,785 Forward loan sale commitments 69 — — 69 69 Mortgage loan commitments 36 — — 36 36 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total (In thousands) December 31, 2016 Financial assets: Cash and cash equivalents $ 30,496 $ 30,496 $ — $ — $ 30,496 Securities available for sale 204,836 43,168 161,668 — 204,836 Securities held to maturity 201,027 — 198,093 — 198,093 Federal Home Loan Bank stock 13,352 — — 13,352 13,352 Loans and loans held for sale, net 1,915,632 — — 1,903,978 1,903,978 Accrued interest receivable 6,057 — — 6,057 6,057 Financial liabilities: Deposits 1,808,687 — — 1,808,629 1,808,629 Borrowings 251,000 — 250,648 — 250,648 On-balance sheet derivative financial instruments: Derivative assets: Interest rate swap agreements 9,024 — 9,024 — 9,024 Forward loan sale commitments 15 — — 15 15 Mortgage loan commitments 111 — — 111 111 Derivative liabilities: Interest rate swap agreements: 8,988 — 8,988 — 8,988 Forward loan sale commitments 74 — — 74 74 Mortgage loan commitments 3 — — 3 3

Other Comprehensive Income (Tab

Other Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	The components of accumulated other comprehensive loss, included in stockholders' equity, are as follows: December 31, 2017 2016 (In thousands) Securities available for sale: Net unrealized gain (loss) $ 283 $ (3,087 ) Tax effect (107 ) 1,007 Net-of-tax amount 176 (2,080 ) Stranded tax effect related to the Act (see Note 2) (33 ) — Securities available for sale, net 143 (2,080 ) Securities held to maturity: Net unrealized gain on transferred securities 250 337 Tax effect (59 ) (114 ) Net-of-tax amount 191 223 Stranded tax effect related to the Act (see Note 2) (7 ) — Securities held to maturity, net 184 223 Defined benefit pension plan: Unrecognized net actuarial loss (2,694 ) (3,482 ) Tax effect 757 1,270 Net-of-tax amount (1,937 ) (2,212 ) Stranded tax effect related to the Act (see Note 2) 157 — Defined benefit pension plan, net (1,780 ) (2,212 ) $ (1,453 ) $ (4,069 )

Condensed Financial Statement44

Condensed Financial Statements of Parent Company (Tables)	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Balance Sheet	Financial information pertaining only to Blue Hills Bancorp, Inc. is as follows: December 31, BALANCE SHEETS 2017 2016 (In thousands) Assets Cash balances at Blue Hills Bank $ 42,111 $ 66,326 Total cash and cash equivalents 42,111 66,326 Investment in Blue Hills Bank 328,740 303,036 Investment in Blue Hills Funding Corp. 26,417 25,165 Other assets 21,146 13,499 Total assets $ 418,414 $ 408,026 Liabilities and Stockholders' Equity Liability to ESOP $ 20,533 $ 20,995 Accrued expenses 75 124 Stockholders' equity 397,806 386,907 Total liabilities and stockholders' equity $ 418,414 $ 408,026
Condensed Statements of Operations	Years Ended December 31, 2017 2016 2015 STATEMENTS OF NET INCOME (In thousands) Operating expenses $ 2,105 $ 2,478 $ 1,860 Loss before income taxes and equity in undistributed net income of subsidiaries $ (2,105 ) $ (2,478 ) $ (1,860 ) Applicable income tax benefit (451 ) (758 ) (1,112 ) Loss before equity in income of subsidiaries (1,654 ) (1,720 ) (748 ) Equity in undistributed net income of subsidiaries 18,143 10,373 7,975 Net income $ 16,489 $ 8,653 $ 7,227
Condensed Cash Flow Statement	Years Ended December 31, 2017 2016 2015 STATEMENTS OF CASH FLOWS (In thousands) Cash flows from operating activities: Net income $ 16,489 $ 8,653 7,227 Adjustments to reconcile net income to net cash provided by (used for) operating activities: Equity in undistributed net income of subsidiaries (18,143 ) (10,373 ) (7,975 ) Excess tax benefit from deferred and stock based compensation — (105 ) (166 ) Net change in other assets (1,164 ) 11,625 (1,157 ) Net change in other liabilities (49 ) 97 (241 ) Net cash provided by (used for) operating activities (2,867 ) 9,897 (2,312 ) Cash flows used for investing activities: Investment in Blue Hills Bank (6,228 ) (16,844 ) (3,929 ) Net cash used for investing activities (6,228 ) (16,844 ) (3,929 ) Cash flows used for financing activities: Excess tax benefit from deferred and stock based compensation — 105 166 Repurchase of common stock — (24,432 ) (13,121 ) Share redemption for tax withholdings (983 ) (730 ) (439 ) Proceeds from exercise of stock options 243 40 — Common and preferred stock dividends paid (14,380 ) (2,675 ) (1,032 ) Net cash used for financing activities (15,120 ) (27,692 ) (14,426 ) Net change in cash and cash equivalents (24,215 ) (34,639 ) (20,667 ) Cash and cash equivalents at beginning of year 66,326 100,965 121,632 Cash and cash equivalents at end of year $ 42,111 $ 66,326 $ 100,965

Selected Quarterly Financial 45

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	First Quarter Second Quarter Third Quarter Fourth Quarter 2017 2016 2017 2016 2017 2016 2017 2016 (In thousands, except share data) Interest and dividend income $ 19,781 $ 16,063 $ 20,574 $ 16,356 $ 21,545 $ 17,685 $ 22,875 $ 19,434 Interest expense 3,900 2,862 4,166 3,040 4,591 3,190 5,081 3,484 Net interest and dividend income 15,881 13,201 16,408 13,316 16,954 14,495 17,794 15,950 Provision (credit) for loan losses 57 (27 ) 1,118 1,113 242 2,872 681 927 Other noninterest income 1,891 1,621 3,582 2,147 2,826 3,834 2,930 3,509 Realized securities gains (losses), net (1,022 ) (244 ) 928 664 — 298 — 298 Gain on exchange of investment in Northeast Retirement Services 5,947 — — — — — — — Total noninterest income 6,816 1,377 4,510 2,811 2,826 4,132 2,930 3,807 Total noninterest expense 13,400 12,068 13,366 12,935 13,355 13,234 14,185 13,509 Provision for income taxes 1,753 870 2,566 721 2,342 891 4,565 1,323 Net income $ 7,487 $ 1,667 $ 3,868 $ 1,358 $ 3,841 $ 1,630 $ 1,293 $ 3,998 Basic earnings per share $ 0.31 $ 0.07 $ 0.16 $ 0.06 $ 0.16 $ 0.07 $ 0.05 $ 0.17 Diluted earnings per share $ 0.31 $ 0.07 $ 0.16 $ 0.05 $ 0.16 $ 0.07 $ 0.05 $ 0.17 Weighted average common shares (basic) 23,911,419 25,066,086 23,952,443 24,575,211 23,973,116 24,129,512 24,104,239 23,919,483 Weighted average common shares (diluted) 24,275,665 25,132,441 24,346,553 24,699,794 24,510,092 24,307,540 24,795,366 24,032,613

Basis of Presentation and Con46

Basis of Presentation and Consolidation - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Subsidiary or Equity Method Investee [Line Items]
Restricted cash and cash equivalents	$ 0	$ 0
Core deposit intangible useful life	5 years 6 months
Contractual commitments for additional capital contributions	$ 9,400,000	8,900,000
Tax benefit from adoption of ASU	$ 448,000
1-4 Family Residential
Subsidiary or Equity Method Investee [Line Items]
Origination covenants, maximum loan-to-value ratio (greater than)	80.00%
Other Assets
Subsidiary or Equity Method Investee [Line Items]
Non-marketable investments	$ 11,300,000	10,200,000
Federal Home Loan Bank of Boston
Subsidiary or Equity Method Investee [Line Items]
Impairments of investments	$ 0	0
Retained Earnings
Subsidiary or Equity Method Investee [Line Items]
Cumulative effect of change in accounting principle		(27,000)
ASU 2016-09 | Retained Earnings
Subsidiary or Equity Method Investee [Line Items]
Cumulative effect of change in accounting principle		$ 27,000

Basis of Presentation and Con47

Basis of Presentation and Consolidation - Schedule of Finite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	$ 1,400	$ 2,625	$ 4,232
Amortization	(843)	(1,225)	(1,607)
Ending balance	$ 557	$ 1,400	$ 2,625

Basis of Presentation and Con48

Basis of Presentation and Consolidation - Estimated Amortization Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
2,018	$ 461
2,019	96
Total remaining	$ 557	$ 1,400	$ 2,625	$ 4,232

Recent Accounting Standards U49

Recent Accounting Standards Updates - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Change in unrealized holding gains (losses)	$ 27,715	$ 12,458	$ 10,064
Total future minimum payments due	21,801
Pro Forma | ASU 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Change in unrealized holding gains (losses)	$ 1,700

Securities - Available-for-sale

Securities - Available-for-sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt securities:
Amortized Cost		$ 162,311
Gross Unrealized Gains		1,323
Gross Unrealized Losses		(1,966)
Fair Value		161,668
Marketable equity securities
Amortized Cost	$ 9,437	45,612
Gross Unrealized Gains	755	73
Gross Unrealized Losses	(472)	(2,517)
Fair Value	9,720	43,168
Available-for-sale securities:
Amortized Cost		207,923
Gross Unrealized Gains		1,396
Gross Unrealized Losses		(4,483)
Fair Value	$ 9,720	204,836
Privately issued commercial mortgage- backed securities
Debt securities:
Amortized Cost		10,530
Gross Unrealized Gains		0
Gross Unrealized Losses		(41)
Fair Value		10,489
Other asset-backed securities
Debt securities:
Amortized Cost		9,174
Gross Unrealized Gains		6
Gross Unrealized Losses		(195)
Fair Value		8,985
Total mortgage- and other asset-backed securities
Debt securities:
Amortized Cost		19,704
Gross Unrealized Gains		6
Gross Unrealized Losses		(236)
Fair Value		19,474
State and political
Debt securities:
Amortized Cost		12,730
Gross Unrealized Gains		120
Gross Unrealized Losses		(157)
Fair Value		12,693
Domestic community
Marketable equity securities
Amortized Cost		3,216
Gross Unrealized Gains		25
Gross Unrealized Losses		(19)
Fair Value		3,222
Global asset allocation
Marketable equity securities
Amortized Cost		42,396
Gross Unrealized Gains		48
Gross Unrealized Losses		(2,498)
Fair Value		39,946
Financial Services | Corporate debt securities
Debt securities:
Amortized Cost		55,765
Gross Unrealized Gains		397
Gross Unrealized Losses		(712)
Fair Value		55,450
Banks | Corporate debt securities
Debt securities:
Amortized Cost		20,263
Gross Unrealized Gains		57
Gross Unrealized Losses		(298)
Fair Value		20,022
Diversified financial entities | Corporate debt securities
Debt securities:
Amortized Cost		17,198
Gross Unrealized Gains		190
Gross Unrealized Losses		(198)
Fair Value		17,190
Insurance and REITs | Corporate debt securities
Debt securities:
Amortized Cost		18,304
Gross Unrealized Gains		150
Gross Unrealized Losses		(216)
Fair Value		18,238
Other Corporate | Corporate debt securities
Debt securities:
Amortized Cost		74,112
Gross Unrealized Gains		800
Gross Unrealized Losses		(861)
Fair Value		74,051
Industrials | Corporate debt securities
Debt securities:
Amortized Cost		49,217
Gross Unrealized Gains		508
Gross Unrealized Losses		(761)
Fair Value		48,964
Utilities | Corporate debt securities
Debt securities:
Amortized Cost		24,895
Gross Unrealized Gains		292
Gross Unrealized Losses		(100)
Fair Value		$ 25,087

Securities - Held-to-maturity S

Securities - Held-to-maturity Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 303,716	$ 201,027
Gross Unrealized Gains	58	18
Gross Unrealized Losses	(4,660)	(2,952)
Fair Value	299,114	198,093
Government-sponsored enterprises
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	30,673	32,667
Gross Unrealized Gains	0	4
Gross Unrealized Losses	(894)	(934)
Fair Value	29,779	31,737
Government-sponsored mortgage-backed and collateralized mortgage obligations
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	244,668	153,938
Gross Unrealized Gains	30	14
Gross Unrealized Losses	(3,437)	(1,806)
Fair Value	241,261	152,146
SBA asset-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	28,375	14,422
Gross Unrealized Gains	28	0
Gross Unrealized Losses	(329)	(212)
Fair Value	$ 28,074	$ 14,210

Securities - Schedule of Contra

Securities - Schedule of Contractual Maturities of Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
After 1 year through 5 years, Held-to-maturity, Amortized Cost	$ 15,626
After 5 years through 10 years, Held-to-maturity, Amortized Cost	15,047
Single Maturity Date, Held-to-maturity, Amortized Cost	30,673
Mortgage- and asset-backed securities and collateralized mortgage obligations amortizing monthly, Held-to-maturity, Amortized Cost	273,043
Amortized Cost	303,716	$ 201,027
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Fair Value [Abstract]
After 1 year through 5 years, Held-to-maturity, Fair Value	15,366
After 5 years through 10 years, Held-to-maturity, Fair Value	14,413
Single Maturity Date, Held-to-maturity, Fair Value	29,779
Mortgage- and asset-backed securities and collateralized mortgage obligations amortizing monthly, Held-to-maturity, Fair Value	269,335
Total debt securities, Held-to-maturity, Fair Value	$ 299,114	$ 198,093

Securities - Available-for-sa53

Securities - Available-for-sale Securities Unrealized Loss (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months		$ (2,101)
Gross Unrealized Losses - More than twelve months		(2,382)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months		94,193
Fair Value - More than twelve months		37,026
Total debt securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months		(1,677)
Gross Unrealized Losses - More than twelve months		(289)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months		79,040
Fair Value - More than twelve months		14,136
Privately issued commercial mortgage- backed securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months		(11)
Gross Unrealized Losses - More than twelve months		(30)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months		3,163
Fair Value - More than twelve months		7,326
Other asset-backed securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months		(43)
Gross Unrealized Losses - More than twelve months		(152)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months		3,924
Fair Value - More than twelve months		3,732
Total other mortgage- and asset-backed securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months	$ (449)	(54)
Gross Unrealized Losses - More than twelve months	(23)	(182)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months	4,310	7,087
Fair Value - More than twelve months	$ 443	11,058
State and political
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months		(157)
Gross Unrealized Losses - More than twelve months		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months		5,301
Fair Value - More than twelve months		0
Total marketable equity securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months		(424)
Gross Unrealized Losses - More than twelve months		(2,093)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months		15,153
Fair Value - More than twelve months		22,890
Domestic community
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months		0
Gross Unrealized Losses - More than twelve months		(19)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months		0
Fair Value - More than twelve months		448
Global asset allocation
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months		(424)
Gross Unrealized Losses - More than twelve months		(2,074)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months		15,153
Fair Value - More than twelve months		22,442
Financial Services | Corporate debt securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months		(712)
Gross Unrealized Losses - More than twelve months		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months		30,822
Fair Value - More than twelve months		0
Banks | Corporate debt securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months		(298)
Gross Unrealized Losses - More than twelve months		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months		14,553
Fair Value - More than twelve months		0
Diversified financial entities | Corporate debt securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months		(198)
Gross Unrealized Losses - More than twelve months		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months		9,369
Fair Value - More than twelve months		0
Insurance and REITs | Corporate debt securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months		(216)
Gross Unrealized Losses - More than twelve months		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months		6,900
Fair Value - More than twelve months		0
Other Corporate | Corporate debt securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months		(754)
Gross Unrealized Losses - More than twelve months		(107)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months		35,830
Fair Value - More than twelve months		3,078
Industrials | Corporate debt securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months		(655)
Gross Unrealized Losses - More than twelve months		(106)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months		24,630
Fair Value - More than twelve months		2,284
Utilities | Corporate debt securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months		(99)
Gross Unrealized Losses - More than twelve months		(1)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months		11,200
Fair Value - More than twelve months		$ 794

Securities - Held-to-maturity54

Securities - Held-to-maturity Securities Unrealized Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months	$ (1,706)	$ (2,801)
Gross Unrealized Losses - More than twelve months	(2,954)	(151)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months	138,200	183,788
Fair Value - More than twelve months	144,393	8,880
Government-sponsored enterprises
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months	(109)	(934)
Gross Unrealized Losses - More than twelve months	(785)	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months	8,521	28,533
Fair Value - More than twelve months	21,258	0
Government-sponsored mortgage-backed and collateralized mortgage obligations
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months	(1,563)	(1,763)
Gross Unrealized Losses - More than twelve months	(1,874)	(43)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months	119,782	146,098
Fair Value - More than twelve months	111,712	3,827
SBA asset-backed securities
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months	(34)	(104)
Gross Unrealized Losses - More than twelve months	(295)	(108)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months	9,897	9,157
Fair Value - More than twelve months	$ 11,423	$ 5,053

Securities - Narrative (Details

Securities - Narrative (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2015USD ($)	Dec. 31, 2017USD ($)mutual_fund	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Schedule of Available-for-sale Securities [Line Items]
Mortgage and asset-backed securities and collateralized mortgage obligations, weighted average duration		3 years 10 months 25 days
Available-for-sale securities, transferred security, at carrying value	$ 196,300
Available-for sale securities, transferred security, unrealized gain (loss)	$ 666
Proceeds for securities available for sale		$ 213,084	$ 97,824	$ 99,522
AFS securities, gross realized gain		2,200	2,300	2,000
AFS securities, gross realized loss		$ 2,300	981	$ 56
Depreciation, percentage of amortized cost basis (less than)		2.00%
Number of mutual funds with unrealized losses | mutual_fund		3
Gross unrealized losses		$ 472	2,517
Government-sponsored enterprises
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale pledged as collateral, amortized cost		30,700	27,300
Securities available for sale pledged as collateral, at fair value		$ 30,300	$ 27,000
Mutual funds
Schedule of Available-for-sale Securities [Line Items]
Depreciation, percentage of amortized cost basis (less than)		9.00%
Gross unrealized losses		$ 472
Accumulated Net Investment Gain (Loss) | Held-to-maturity Securities
Schedule of Available-for-sale Securities [Line Items]
Other comprehensive income (loss), held-to-maturity securities adjustment, before tax		$ 250

Loans and The Allowance for L56

Loans and The Allowance for Loan Losses - Summary of Loan balances (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 2,203,810	$ 1,929,028
Allowance for loan losses	(20,877)	(18,750)
Discount and fair value adjustments on purchased loans	(1,477)	(1,846)
Deferred loan costs and fees, net	4,691	4,439
Loans, net	2,186,147	1,912,871
Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,928,603	1,693,513
1-4 Family Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	922,627	851,154
Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	80,662	78,719
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	834,264	687,289
Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	91,050	76,351
Commercial Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	253,509	206,234
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 21,698	$ 29,281

Loans and The Allowance for L57

Loans and The Allowance for Loan Losses - Additional Information (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructurings	$ 973,000	$ 0	$ 0
Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid principal balance	245,100,000	89,700,000
Transferor's continuing involvement, arrangements of financial support, amount	7,600,000
1-4 Family Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans pledged to secure debt	816,900,000	759,900,000
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid principal balance	88,800,000	56,000,000
Loans pledged to secure debt	$ 266,300,000	$ 293,100,000

Loans and The Allowance for L58

Loans and The Allowance for Loan Losses - Activity in Allowance for Loan Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for Credit Losses, beginning balance	$ 18,750	$ 17,102	$ 12,973
Provision for loan losses	2,098	4,885	4,090
Loans charged-off	(259)	(3,475)	(43)
Recoveries	288	238	82
Allowance for Credit Losses, ending balance	20,877	18,750	17,102
1-4 Family Residential
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for Credit Losses, beginning balance	4,846	3,916	3,222
Provision for loan losses	83	830	612
Loans charged-off	(52)	0	0
Recoveries	199	100	82
Allowance for Credit Losses, ending balance	5,076	4,846	3,916
Home Equity
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for Credit Losses, beginning balance	537	636	340
Provision for loan losses	162	(99)	296
Loans charged-off	0	0	0
Recoveries	0	0	0
Allowance for Credit Losses, ending balance	699	537	636
Commercial Real Estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for Credit Losses, beginning balance	8,374	7,147	3,551
Provision for loan losses	1,283	1,447	3,596
Loans charged-off	(73)	(321)	0
Recoveries	0	101	0
Allowance for Credit Losses, ending balance	9,584	8,374	7,147
Construction
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for Credit Losses, beginning balance	1,353	1,364	1,056
Provision for loan losses	355	(11)	308
Loans charged-off	0	0	0
Recoveries	0	0	0
Allowance for Credit Losses, ending balance	1,708	1,353	1,364
Commercial Business
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for Credit Losses, beginning balance	3,206	2,839	3,410
Provision for loan losses	193	3,428	(571)
Loans charged-off	0	(3,098)	0
Recoveries	74	37	0
Allowance for Credit Losses, ending balance	3,473	3,206	2,839
Consumer
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for Credit Losses, beginning balance	434	772	736
Provision for loan losses	22	(282)	79
Loans charged-off	(134)	(56)	(43)
Recoveries	15	0	0
Allowance for Credit Losses, ending balance	337	434	772
Unallocated
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for Credit Losses, beginning balance	0	428	658
Provision for loan losses	0	(428)	(230)
Loans charged-off	0	0	0
Recoveries	0	0	0
Allowance for Credit Losses, ending balance	$ 0	$ 0	$ 428

Loans and The Allowance for L59

Loans and The Allowance for Loan Losses - Additional Activity in Allowance for Loan Losses (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance related to impaired loans	$ 81	$ 17
Allowance related to non-impaired loans	20,796	18,733
Total allowance for loan losses	20,877	18,750	$ 17,102	$ 12,973
Impaired loans	12,282	9,231
Non-impaired loans	2,191,528	1,919,797
Total loans	2,203,810	1,929,028
1-4 Family Residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance related to impaired loans	80	17
Allowance related to non-impaired loans	4,996	4,829
Total allowance for loan losses	5,076	4,846	3,916	3,222
Impaired loans	5,949	6,726
Non-impaired loans	916,678	844,428
Total loans	922,627	851,154
Home Equity
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance related to impaired loans	0	0
Allowance related to non-impaired loans	699	537
Total allowance for loan losses	699	537	636	340
Impaired loans	1,387	1,153
Non-impaired loans	79,275	77,566
Total loans	80,662	78,719
Commercial Real Estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance related to impaired loans	0	0
Allowance related to non-impaired loans	9,584	8,374
Total allowance for loan losses	9,584	8,374	7,147	3,551
Impaired loans	4,744	941
Non-impaired loans	829,520	686,348
Total loans	834,264	687,289
Construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance related to impaired loans	0	0
Allowance related to non-impaired loans	1,708	1,353
Total allowance for loan losses	1,708	1,353	1,364	1,056
Impaired loans	0	0
Non-impaired loans	91,050	76,351
Total loans	91,050	76,351
Commercial Business
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance related to impaired loans	0	0
Allowance related to non-impaired loans	3,473	3,206
Total allowance for loan losses	3,473	3,206	2,839	3,410
Impaired loans	0	241
Non-impaired loans	253,509	205,993
Total loans	253,509	206,234
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance related to impaired loans	1	0
Allowance related to non-impaired loans	336	434
Total allowance for loan losses	337	434	772	736
Impaired loans	202	170
Non-impaired loans	21,496	29,111
Total loans	21,698	29,281
Unallocated
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance related to impaired loans	0	0
Allowance related to non-impaired loans	0	0
Total allowance for loan losses	0	0	$ 428	$ 658
Impaired loans	0	0
Non-impaired loans	0	0
Total loans	$ 0	$ 0

Loans and The Allowance for L60

Loans and The Allowance for Loan Losses - Summary of Past Due and Non-accrual loans, by class (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 8,190	$ 11,591
Loans on Non-accrual	11,523	8,983
1-4 Family Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,913	3,279
Loans on Non-accrual	5,190	6,478
Home Equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,178	1,723
Loans on Non-accrual	1,387	1,153
Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,893	1,393
Loans on Non-accrual	4,744	941
Commercial Business
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		5,009
Loans on Non-accrual		241
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	206	187
Loans on Non-accrual	202	170
30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	997	7,600
30-59 Days Past Due | 1-4 Family Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	381	584
30-59 Days Past Due | Home Equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	509	452
30-59 Days Past Due | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	1,393
30-59 Days Past Due | Commercial Business
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		4,996
30-59 Days Past Due | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	107	175
60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	368	887
60-89 Days Past Due | 1-4 Family Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	348	373
60-89 Days Past Due | Home Equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	13	496
60-89 Days Past Due | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
60-89 Days Past Due | Commercial Business
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		13
60-89 Days Past Due | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	7	5
Past Due 90 Days or More
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	6,825	3,104
Past Due 90 Days or More | 1-4 Family Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,184	2,322
Past Due 90 Days or More | Home Equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	656	775
Past Due 90 Days or More | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,893	0
Past Due 90 Days or More | Commercial Business
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		0
Past Due 90 Days or More | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 92	$ 7

Loans and The Allowance for L61

Loans and The Allowance for Loan Losses - Summary of Impaired Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Recorded Investment
Recorded Investment, without a valuation allowance	$ 10,823	$ 9,110
Recorded investment, with valuation allowance	1,459
Recorded investment, total	12,282	9,231
Unpaid Principal Balance
Unpaid Principal Balance, without a valuation allowance	11,880	12,917
Unpaid Principal Balance, with a valuation allowance	1,459
Unpaid Principal Balance, total	13,339	13,230
Related Allowance	81	17
1-4 Family Residential
Recorded Investment
Recorded Investment, without a valuation allowance	4,501	6,605
Recorded investment, with valuation allowance	1,448	121
Unpaid Principal Balance
Unpaid Principal Balance, without a valuation allowance	4,897	7,023
Unpaid Principal Balance, with a valuation allowance	1,448	313
Related Allowance	80	17
Home Equity
Recorded Investment
Recorded Investment, without a valuation allowance	1,387	1,153
Unpaid Principal Balance
Unpaid Principal Balance, without a valuation allowance	1,523	1,225
Commercial Real Estate
Recorded Investment
Recorded Investment, without a valuation allowance	4,744	941
Unpaid Principal Balance
Unpaid Principal Balance, without a valuation allowance	5,206	1,207
Commercial Business
Recorded Investment
Recorded Investment, without a valuation allowance	0	241
Unpaid Principal Balance
Unpaid Principal Balance, without a valuation allowance	11	3,279
Consumer
Recorded Investment
Recorded Investment, without a valuation allowance	191	170
Recorded investment, with valuation allowance	11
Unpaid Principal Balance
Unpaid Principal Balance, without a valuation allowance	243	$ 183
Unpaid Principal Balance, with a valuation allowance	11
Related Allowance	$ 1

Loans and The Allowance for L62

Loans and The Allowance for Loan Losses - Summary of Average Recorded Investments and Interest Income of Impaired Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Impaired [Line Items]
Average Recorded Investment, without a valuation allowance	$ 12,013	$ 11,030	$ 6,450
Interest Income Recognized, without a valuation allowance	588	751	452
Consumer Excluding Consumer Other Portfolio Segment | 1-4 Family Residential
Financing Receivable, Impaired [Line Items]
Average Recorded Investment, without a valuation allowance	6,254	6,451	4,869
Interest Income Recognized, without a valuation allowance	281	449	270
Consumer Excluding Consumer Other Portfolio Segment | Home Equity
Financing Receivable, Impaired [Line Items]
Average Recorded Investment, without a valuation allowance	1,264	555	575
Interest Income Recognized, without a valuation allowance	58	29	14
Consumer Excluding Consumer Other Portfolio Segment | Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Average Recorded Investment, without a valuation allowance	4,125	3,192	926
Interest Income Recognized, without a valuation allowance	220	206	161
Commercial Business
Financing Receivable, Impaired [Line Items]
Average Recorded Investment, without a valuation allowance	129	672	2
Interest Income Recognized, without a valuation allowance	20	55	1
Consumer
Financing Receivable, Impaired [Line Items]
Average Recorded Investment, without a valuation allowance	241	160	78
Interest Income Recognized, without a valuation allowance	$ 9	$ 12	$ 6

Loans and The Allowance for L63

Loans and The Allowance for Loan Losses - Summary of Loan by Risk Rating (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Total loans	$ 2,203,810	$ 1,929,028
1-4 Family Residential
Financing Receivable, Recorded Investment [Line Items]
Total loans	922,627	851,154
Home Equity
Financing Receivable, Recorded Investment [Line Items]
Total loans	80,662	78,719
Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	834,264	687,289
Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans	91,050	76,351
Commercial Business
Financing Receivable, Recorded Investment [Line Items]
Total loans	253,509	206,234
Consumer
Financing Receivable, Recorded Investment [Line Items]
Total loans	21,698	29,281
Loans rated 1 - 6
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,166,925	938,280
Loans rated 1 - 6 | 1-4 Family Residential
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,022	1,054
Loans rated 1 - 6 | Home Equity
Financing Receivable, Recorded Investment [Line Items]
Total loans	270	293
Loans rated 1 - 6 | Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	821,815	671,872
Loans rated 1 - 6 | Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans	91,050	76,351
Loans rated 1 - 6 | Commercial Business
Financing Receivable, Recorded Investment [Line Items]
Total loans	252,765	188,706
Loans rated 1 - 6 | Consumer
Financing Receivable, Recorded Investment [Line Items]
Total loans	3	4
Loans rated 7
Financing Receivable, Recorded Investment [Line Items]
Total loans	9,896	31,857
Loans rated 7 | 1-4 Family Residential
Financing Receivable, Recorded Investment [Line Items]
Total loans	2,848	3,514
Loans rated 7 | Home Equity
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,523	967
Loans rated 7 | Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	4,660	9,720
Loans rated 7 | Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loans rated 7 | Commercial Business
Financing Receivable, Recorded Investment [Line Items]
Total loans	744	17,510
Loans rated 7 | Consumer
Financing Receivable, Recorded Investment [Line Items]
Total loans	121	146
Loans rated 8
Financing Receivable, Recorded Investment [Line Items]
Total loans	10,355	8,452
Loans rated 8 | 1-4 Family Residential
Financing Receivable, Recorded Investment [Line Items]
Total loans	2,566	2,442
Loans rated 8 | Home Equity
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	258
Loans rated 8 | Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	7,789	5,697
Loans rated 8 | Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loans rated 8 | Commercial Business
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	18
Loans rated 8 | Consumer
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	37
Loans rated 9
Financing Receivable, Recorded Investment [Line Items]
Total loans	250	645
Loans rated 9 | 1-4 Family Residential
Financing Receivable, Recorded Investment [Line Items]
Total loans	250	645
Loans rated 9 | Home Equity
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loans rated 9 | Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loans rated 9 | Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loans rated 9 | Commercial Business
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loans rated 9 | Consumer
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loans rated 10
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loans rated 10 | 1-4 Family Residential
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loans rated 10 | Home Equity
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loans rated 10 | Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loans rated 10 | Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loans rated 10 | Commercial Business
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loans rated 10 | Consumer
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loans not rated
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,016,384	949,794
Loans not rated | 1-4 Family Residential
Financing Receivable, Recorded Investment [Line Items]
Total loans	915,941	843,499
Loans not rated | Home Equity
Financing Receivable, Recorded Investment [Line Items]
Total loans	78,869	77,201
Loans not rated | Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loans not rated | Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loans not rated | Commercial Business
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loans not rated | Consumer
Financing Receivable, Recorded Investment [Line Items]
Total loans	$ 21,574	$ 29,094

Premises and Equipment (Details

Premises and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 35,584	$ 33,925
Less accumulated depreciation and amortization	(14,011)	(11,891)
Premises and equipment, net	21,573	22,034
Depreciation and amortization of premises and equipment	2,100	2,000	$ 1,800
Land
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	4,087	4,087
Buildings
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 11,043	10,322
Buildings | Minimum
Property, Plant and Equipment [Line Items]
Useful life (in years)	5 years
Buildings | Maximum
Property, Plant and Equipment [Line Items]
Useful life (in years)	40 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 9,551	9,334
Leasehold improvements | Minimum
Property, Plant and Equipment [Line Items]
Useful life (in years)	5 years
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Useful life (in years)	10 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 4,139	3,874
Furniture and fixtures | Minimum
Property, Plant and Equipment [Line Items]
Useful life (in years)	3 years
Furniture and fixtures | Maximum
Property, Plant and Equipment [Line Items]
Useful life (in years)	5 years
Technology equipment
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 6,579	6,139
Technology equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful life (in years)	1 year
Technology equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful life (in years)	3 years
Construction in progress
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 185	$ 169

Deposits - Summary of Deposit B

Deposits - Summary of Deposit Balances (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Banking and Thrift [Abstract]
NOW and demand	$ 381,316	$ 331,508
Regular savings	221,004	262,984
Money market	646,603	573,204
Brokered money market	92,798	53,357
Total non-certificate accounts	1,341,721	1,221,053
Term certificates of $250,000 or more	134,649	77,550
Term certificates less than $250,000	313,733	262,564
Brokered certificates of deposit	249,766	247,520
Total certificate accounts	698,148	587,634
Total deposits	$ 2,039,869	$ 1,808,687

Deposits - Schedule of Contract

Deposits - Schedule of Contractual Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Time Deposits, Fiscal Year Maturity [Abstract]
Amount - 2018	$ 406,362
Amount - 2019	180,672
Amount - 2020	62,733
Amount - 2021	19,513
Amount - 2022	28,868
Total certificate accounts	$ 698,148	$ 587,634
Weighted Average Rate of Time Deposits [Abstract]
Weighted Average Rate - 2018	1.18%
Weighted Average Rate - 2019	1.72%
Weighted Average Rate - 2020	1.79%
Weighted Average Rate - 2021	1.84%
Weighted Average Rate - 2022	2.04%
Weighted Average Rate	1.43%

Borrowings - Additional Informa

Borrowings - Additional Information (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Federal Home Loan Bank of Boston
Debt Instrument [Line Items]
FFHLB advances with an original maturity of less than one year	$ 100,000,000	$ 146,000,000
Weighted average rate (percent)	1.57%	0.76%
Line of Credit | Federal Home Loan Bank of Boston
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 7,700,000	$ 7,700,000
Line of credit, amount outstanding	0	0
Unsecured Federal Funds Line of Credit | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	42,000,000	42,000,000
Line of credit, amount outstanding	$ 0	$ 0

Borrowings - FHLB Advances Fisc

Borrowings - FHLB Advances Fiscal Year Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Federal Home Loan Bank, Advances, Fiscal Year Maturity [Abstract]
2,017	$ 0	$ 15,000
2,018	25,000	20,000
2,019	35,000	25,000
2,020	35,000	15,000
2,021	0	30,000
2,022	10,000	0
Total FHLB advances	$ 105,000	$ 105,000
Federal Home Loan Bank, Advances, Maturities Summary, Average Interest Rate of Amounts Due [Abstract]
2,017	0.00%	1.99%
2,018	1.97%	2.12%
2,019	1.32%	1.20%
2,020	1.70%	1.49%
2,021	0.00%	0.28%
2,022	0.42%	0.00%
Weighted average rate	1.51%	1.27%

Income Taxes - Provisions (Bene

Income Taxes - Provisions (Benefit) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current tax provision:
Federal									$ 6,984	$ 3,617	$ 2,933
State									1,551	306	206
Current income tax provision									8,535	3,923	3,139
Deferred tax provision (benefit):
Federal									1,792	344	7
State									77	47	(148)
Statutory rate change									2,500	(289)	0
Federal and State									4,369	102	(141)
Change in valuation reserve									(1,678)	(220)	(161)
Deferred income tax provision (benefit)									2,691	(118)	(302)
Provision for income taxes	$ 4,565	$ 2,342	$ 2,566	$ 1,753	$ 1,323	$ 891	$ 721	$ 870	$ 11,226	$ 3,805	$ 2,837

Income Taxes - Effective Income

Income Taxes - Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Statutory federal tax provision									$ 9,700	$ 4,236	$ 3,429
Increase (decrease) resulting from:
State taxes, net of federal tax benefit									1,058	233	39
Dividends received deduction									(26)	(41)	(211)
Tax-exempt bank-owned life insurance									(372)	(528)	(351)
Tax-exempt interest									(155)	(189)	(222)
Change in valuation reserve									(1,678)	(220)	(161)
Equity incentives									121	339	52
Amortization of low income housing partnership									166	219	0
Tax credits utilized									(188)	(286)	(45)
Accrual adjustment									23	207	13
Statutory rate change									2,500	(289)	0
Other, net									77	124	294
Provision for income taxes	$ 4,565	$ 2,342	$ 2,566	$ 1,753	$ 1,323	$ 891	$ 721	$ 870	$ 11,226	$ 3,805	$ 2,837
Effective tax rates									40.50%	30.50%	28.20%

Income Taxes - Components of De

Income Taxes - Components of Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Examination [Line Items]
Deferred tax assets, gross	$ 10,158	$ 14,958
Valuation reserve	(112)	(1,790)
Deferred tax assets, net	10,046	13,168
Deferred tax liabilities	(4,046)	(3,022)
Net deferred tax asset	6,000	10,146	$ 10,665	$ 6,233
Federal
Income Tax Examination [Line Items]
Deferred tax assets, gross	6,742	11,700
Deferred tax liabilities	(3,050)	(2,427)
State
Income Tax Examination [Line Items]
Deferred tax assets, gross	3,416	3,258
Deferred tax liabilities	$ (996)	$ (595)

Income Taxes - Tax Effect on De

Income Taxes - Tax Effect on Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Depreciation and amortization	$ 279	$ 747
Employee benefit plans and share-based compensation plans	410	571
Allowance for loan losses	5,868	7,660
Contribution carryover	1,122	2,317
Net unrealized gain on securities held as, or transferred from, available for sale	0	893
Net unrealized losses on defined benefit pension plan	757	1,270
Deferred rent expense	170	123
Other	(31)	0
Valuation reserve	(112)	(1,790)
Deferred tax liabilities:
Deferred loan origination costs	(1,338)	(1,947)
Net unrealized gain on securities held as, or transferred from, available for sale	(166)	0
Gain on exchange of investment in Northeast Retirement Services	(959)	0
Other	0	302
Net deferred tax asset	$ 6,000	$ 10,146	$ 10,665	$ 6,233

Income Taxes - Changes in Defer

Income Taxes - Changes in Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Increase (Decrease) In Deferred Taxes [Roll Forward]
Balance at beginning of year	$ 10,146	$ 10,665	$ 6,233
Deferred tax (provision) benefit	(2,691)	118	302
Tax effect of changes in accumulated other comprehensive income	(1,455)	(637)	4,130
Balance at end of year	$ 6,000	$ 10,146	$ 10,665

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Examination [Line Items]
Additional income tax expense attributable to TCJA	$ 2,500
Tax benefit from change in statutory rate		$ (2,500)	$ 289	$ 0
Deferred tax assets, valuation allowance	112	$ 112	1,790
Bad debt reserve for tax purposes of qualified lender, percentage of reserve subject taxation		150.00%
Income taxes, penalties and interest expense		$ 13	22	0
Change in valuation reserve		1,678	$ 220	$ 161
Federal
Income Tax Examination [Line Items]
Bad debt reserve for tax purposes of qualified lender	1,300	1,300
Deferred income tax liability not recognized	$ 354	$ 354

Equity - Additional Information

Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2015
Class of Stock [Line Items]
Tier 1 capital conservation buffer common equity to RWA (percent) (greater than)	0.625%		2.50%
Tier 1 capital conservation buffer common equity capital to RWA, phasing period (years)	3 years
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, par value (dollars per share)	$ 0	$ 0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Retained earnings, unappropriated	$ 36,500
Funds available for loans or advances from the Bank	31,900
Liquidation account amount	49,000	$ 61,000
Blue Hills Bank
Class of Stock [Line Items]
Equity restrictions	166,400
Parent Company
Class of Stock [Line Items]
Investment in Blue Hills Bank	$ 328,740	$ 303,036

Equity - Minimum Required Capit

Equity - Minimum Required Capital (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Total capital (to risk weighted assets)
Actual - Total Capital to Risk Weighted Assets	$ 410,088	$ 395,325
Actual - Total Capital to Risk Weighted Assets (percent)	19.70%	20.50%
Minimum Capital Requirement - Total Capital to Risk Weighted Assets	$ 166,635	$ 154,471
Minimum Capital Requirement - Total Capital to Risk Weighted Assets (percent)	8.00%	8.00%
Minimum to Be Well Capitalized - Total Capital to Risk Weighted Assets	$ 208,294	$ 193,089
Minimum to Be Well Capitalized - Total Capital to Risk Weighted Assets (percent)	10.00%	10.00%
Tier 1 capital (to risk weighted assets)
Actual - Tier 1 Capital to Risk Weighted Assets	$ 389,211	$ 376,575
Actual - Tier 1 Capital to Risk Weighted Assets (percent)	18.70%	19.50%
Minimum Capital Requirement - Tier 1 Capital to Risk Weighted Assets	$ 124,977	$ 115,854
Minimum Capital Requirement - Tier 1 Capital to Risk Weighted Assets (percent)	6.00%	6.00%
Minimum to Be Well Capitalized - Tier 1 Capital to Risk Weighted Assets	$ 166,635	$ 154,471
Minimum to Be Well Capitalized - Tier 1 Capital to Risk Weighted Assets (percent)	8.00%	8.00%
Common equity Tier 1 (to risk weighted assets)
Actual - Common Equity to Risk Weighted Assets	$ 389,211	$ 376,575
Actual - Common Equity to Risk Weighted Assets (percent)	18.70%	19.50%
Minimum Capital Requirement - Common Equity to Risk Weighted Assets	$ 93,732	$ 86,890
Minimum Capital Requirement - Common Equity to Risk Weighted Assets (percent)	4.50%	4.50%
Minimum to Be Well Capitalized - Common Equity to Risk Weighted Assets	$ 135,391	$ 125,508
Minimum to Be Well Capitalized - Common Equity to Risk Weighted Assets (percent)	6.50%	6.50%
Tier 1 capital (to average assets)
Actual - Tier 1 Capital to Average Assets	$ 389,211	$ 376,575
Actual - Tier 1 Capital to Average Assets (percent)	14.90%	16.00%
Minimum Capital Requirement - Tier 1 Capital to Average Assets	$ 104,278	$ 94,166
Minimum Capital Requirement - Tier 1 Capital to Average Assets (percent)	4.00%	4.00%
Minimum To Be Well Capitalized - Tier 1 Capital to Average Assets	$ 130,348	$ 117,708
Minimum To Be Well Capitalized - Tier 1 Capital to Average Assets (percent)	5.00%	5.00%
Blue Hills Bank
Total capital (to risk weighted assets)
Actual - Total Capital to Risk Weighted Assets	$ 341,175	$ 313,457
Actual - Total Capital to Risk Weighted Assets (percent)	16.40%	16.30%
Minimum Capital Requirement - Total Capital to Risk Weighted Assets	$ 166,391	$ 154,196
Minimum Capital Requirement - Total Capital to Risk Weighted Assets (percent)	8.00%	8.00%
Minimum to Be Well Capitalized - Total Capital to Risk Weighted Assets	$ 207,988	$ 192,745
Minimum to Be Well Capitalized - Total Capital to Risk Weighted Assets (percent)	10.00%	10.00%
Tier 1 capital (to risk weighted assets)
Actual - Tier 1 Capital to Risk Weighted Assets	$ 320,298	$ 294,707
Actual - Tier 1 Capital to Risk Weighted Assets (percent)	15.40%	15.30%
Minimum Capital Requirement - Tier 1 Capital to Risk Weighted Assets	$ 124,793	$ 115,647
Minimum Capital Requirement - Tier 1 Capital to Risk Weighted Assets (percent)	6.00%	6.00%
Minimum to Be Well Capitalized - Tier 1 Capital to Risk Weighted Assets	$ 166,391	$ 154,196
Minimum to Be Well Capitalized - Tier 1 Capital to Risk Weighted Assets (percent)	8.00%	8.00%
Common equity Tier 1 (to risk weighted assets)
Actual - Common Equity to Risk Weighted Assets	$ 320,298	$ 294,707
Actual - Common Equity to Risk Weighted Assets (percent)	15.40%	15.30%
Minimum Capital Requirement - Common Equity to Risk Weighted Assets	$ 93,595	$ 86,735
Minimum Capital Requirement - Common Equity to Risk Weighted Assets (percent)	4.50%	4.50%
Minimum to Be Well Capitalized - Common Equity to Risk Weighted Assets	$ 135,192	$ 125,284
Minimum to Be Well Capitalized - Common Equity to Risk Weighted Assets (percent)	6.50%	6.50%
Tier 1 capital (to average assets)
Actual - Tier 1 Capital to Average Assets	$ 320,298	$ 294,707
Actual - Tier 1 Capital to Average Assets (percent)	12.30%	12.50%
Minimum Capital Requirement - Tier 1 Capital to Average Assets	$ 104,137	$ 94,099
Minimum Capital Requirement - Tier 1 Capital to Average Assets (percent)	4.00%	4.00%
Minimum To Be Well Capitalized - Tier 1 Capital to Average Assets	$ 130,171	$ 117,623
Minimum To Be Well Capitalized - Tier 1 Capital to Average Assets (percent)	5.00%	5.00%

Employee Benefit Plans - Additi

Employee Benefit Plans - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Jan. 01, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Employer contribution		$ 1,110	$ 470	$ 0
401(k) Plan, minimum service period required to be a participant (months)			3 months
401(k) Employer non-elective contribution based on earnings (percent)	3.00%
401(k) Employer elective contribution based on earnings (percent)	2.00%
401(k) plan expense	4.00%
401(k) Employer matching contribution, percent match, first 3%	100.00%
401(k) Employer matching contribution, percent match, remaining 2%	50.00%
401(k) Employer matching contribution (percent)		670	$ 784	610
Short-term Incentive Compensation expense		$ 2,900	2,500	2,300
Employee stock ownership plan, shares		2,277,345
Shares issued (in dollars per share)		$ 10
ESOP, term of loan (years)		30 years
ESOP, interest rate (percent)		4.50%
ESOP, number of annual committed-to-be-released shares		75,912
ESOP, number of suspense shares fair value		$ 39,700	38,400
ESOP expense		$ 1,431	$ 1,130	1,063
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate		3.43%	3.86%
Net periodic pension cost (benefit)		$ 246	$ (27)	$ (234)
Parent Company
Defined Benefit Plan Disclosure [Line Items]
ESOP, loan balance		$ 20,533	$ 20,995
Minimum | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation		40.00%
Minimum | Fixed Income Funds
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation		15.00%
Minimum | Other Investments
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation		25.00%
Maximum | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation		64.00%
Maximum | Fixed Income Funds
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation		25.00%
Maximum | Other Investments
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocation		41.00%

Employee Benefit Plans - Accumu

Employee Benefit Plans - Accumulated Benefit Obligations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in plan assets:
Employer contribution	$ 1,110	$ 470	$ 0
Pension Plan
Change in plan assets:
Fair value of plan assets at beginning of year	9,811	8,814	9,443
Actual return (loss) on plan assets	1,414	847	(304)
Benefits paid	(178)	(320)	(325)
Settlement payments	(1,394)	0	0
Fair value of plan assets at end of year	10,763	9,811	8,814
Change in benefit obligation:
Benefit obligation at beginning of year	11,896	10,772	10,135
Interest cost	390	422	401
Actuarial loss	481	1,022	561
Benefits paid	(178)	(320)	(325)
Settlement payments	1,394	0	0
Benefit obligation at end of year	11,195	11,896	10,772
Funded status and accrued liability at end of year	(432)	(2,085)	(1,958)
Accumulated benefit obligation at end of year	$ 11,195	$ 11,896	$ 10,772

Employee Benefit Plans - Net Pe

Employee Benefit Plans - Net Periodic Pension Costs (Details) - Pension Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 390	$ 422	$ 401
Expected return on plan assets	(758)	(720)	(745)
Amortization of net actuarial loss	297	271	110
Settlement loss	317	0	0
Net periodic pension cost (benefit)	$ 246	$ (27)	$ (234)

Employee Benefit Plans - Net 80

Employee Benefit Plans - Net Periodic Pension Costs Assumptions Used (Details) - Pension Plan	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.86%	4.01%	4.00%
Expected long-term rate of return on plan assets	8.00%	8.00%	8.00%

Employee Benefit Plans - Fair V

Employee Benefit Plans - Fair Value of Pension Plan Assets (Details) - Pension Plan - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Investments measure in the fair value hierarchy	$ 4,912	$ 3,943
Investments measured at net asset value	5,851	5,868
Total plan investment assets, at fair value	10,763	9,811	$ 8,814	$ 9,443
Level 1
Defined Benefit Plan Disclosure [Line Items]
Investments measure in the fair value hierarchy	4,912	3,943
Total plan investment assets, at fair value	4,912	3,943
Level 2
Defined Benefit Plan Disclosure [Line Items]
Investments measure in the fair value hierarchy	0	0
Total plan investment assets, at fair value	0	0
Level 3
Defined Benefit Plan Disclosure [Line Items]
Investments measure in the fair value hierarchy	0	0
Total plan investment assets, at fair value	0	0
Collective funds
Defined Benefit Plan Disclosure [Line Items]
Total plan investment assets, at fair value	420	681
Collective funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan investment assets, at fair value	420	681
Collective funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan investment assets, at fair value	0	0
Collective funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan investment assets, at fair value	0	0
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Total plan investment assets, at fair value	2,413	1,929
Equity securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan investment assets, at fair value	2,413	1,929
Equity securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan investment assets, at fair value	0	0
Equity securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan investment assets, at fair value	0	0
Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Total plan investment assets, at fair value	2,079	1,209
Mutual funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan investment assets, at fair value	2,079	1,209
Mutual funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan investment assets, at fair value	0	0
Mutual funds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan investment assets, at fair value	$ 0	0
Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Total plan investment assets, at fair value		124
Short-term investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total plan investment assets, at fair value		124
Short-term investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total plan investment assets, at fair value		0
Short-term investments | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total plan investment assets, at fair value		$ 0

Employee Benefit Plans - Expect

Employee Benefit Plans - Expected Benefit Payments (Details) $ in Thousands	Dec. 31, 2017USD ($)
Retirement Benefits [Abstract]
2,018	$ 843
2,019	505
2,020	684
2,021	933
2,022	628
2023-2027	$ 2,880

Employee Benefit Plans - Employ

Employee Benefit Plans - Employee Stock Ownership Plan (Details) - shares	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Allocated	219,860	149,613
Committed to be allocated	75,912	75,912
Unallocated	1,973,699	2,049,608
Total	2,269,471	2,275,133

Stock Based Compensation - Addi

Stock Based Compensation - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized		2,846,681
Term (years)		10 years	10 years	10 years
Vesting period (years)	5 years	5 years	5 years	5 years
Share-based compensation expense		$ 2,300	$ 2,100	$ 473
Tax benefit related to share-based compensation expense		$ 657	502	112
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized		1,138,673
Share-based compensation expense		$ 3,200	2,800	651
Tax benefit related to share-based compensation expense		$ 1,300	$ 987	$ 228
Granted (shares)		184,695
Vested (shares)		185,028
Nonvested (shares)		730,420	816,070
Forfeited (shares)		85,317
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (shares)		40,000
Vested (shares)		6,000
Nonvested (shares)		32,000
Forfeited (shares)		2,000
Maximum | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term (years)		10 years

Stock Based Compensation - Fair

Stock Based Compensation - Fair Value Assumptions (Details) - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (shares)		412,100
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (shares)		412,100	55,000	2,434,000
Vesting period (years)	5 years	5 years	5 years	5 years
Term (years)		10 years	10 years	10 years
Fair value calculation assumptions:
Expected volatility (percent)			28.47%	28.85%
Expected life (years)		6 years 6 months	6 years 6 months	6 years 6 months
Expected dividend yield (percent)			0.58%	0.54%
Risk free interest rate (percent)			1.38%	1.55%
Fair value per option (dollars per share)			$ 4.02	$ 4.23
Weighted average grant date fair value (in usd per share)		$ 5.09	$ 4.02	$ 4.23
Minimum | Stock Options
Fair value calculation assumptions:
Expected volatility (percent)		26.91%
Expected dividend yield (percent)		0.71%
Risk free interest rate (percent)		1.87%
Fair value per option (dollars per share)		$ 4.07
Maximum | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term (years)		10 years
Fair value calculation assumptions:
Expected volatility (percent)		27.43%
Expected dividend yield (percent)		2.22%
Risk free interest rate (percent)		2.16%
Fair value per option (dollars per share)		$ 5.31

Stock Based Compensation - Stoc

Stock Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning balance (shares)	2,449,670
Granted (shares)	412,100
Forfeited (shares)	(159,650)
Exercised (shares)	(17,470)
Ending balance (shares)	2,684,650	2,449,670
Exercisable at end of period (shares)	925,990
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Beginning balance, weighted average exercise price (dollars per share)	$ 14.06
Granted, weighted average exercise price (dollars per share)	18.22
Forfeited, weighted average exercise price (dollars per share)	14.18
Exercised, weighted average exercise price (dollars per share)	13.9
Ending balance, weighted average exercise price (dollars per share)	14.70	$ 14.06
Exercisable at end of period, weighted average exercise price (dollars per share)	$ 14.07
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Outstanding, weighted average remaining contractual term (years)	7 years 11 months 23 days
Exercisable, weighted average remaining contractual term (years)	7 years 9 months
Outstanding, aggregate intrinsic value	$ 14,506
Exercisable, aggregate intrinsic value	5,584
Exercised, aggregate intrinsic value	$ 77
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Granted (shares)	412,100	55,000	2,434,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Unrecognized compensation cost inclusive of directors' options at December 31, 2017	$ 6,950
Weighted average remaining recognition period (years)	3 years 1 month 13 days

Stock Based Compensation - Rest

Stock Based Compensation - Restricted Stock Activity (Details) - Restricted Stock $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Beginning balance (shares) | shares	816,070
Granted (shares) | shares	184,695
Vested (shares) | shares	(185,028)
Forfeited (shares) | shares	(85,317)
Ending balance (shares) | shares	730,420
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Beginning balance, weighted average exercise price (dollars per share) | $ / shares	$ 14.06
Granted, weighted average exercise price (dollars per share) | $ / shares	18.25
Vested, weighted average exercise price (dollars per share) | $ / shares	14.06
Forfeited, weighted average exercise price (dollars per share) | $ / shares	14.11
Ending balance, weighted average exercise price (dollars per share) | $ / shares	$ 15.11
Unrecognized compensation cost inclusive of directors' awards at December 31, 2017 | $	$ 9,704
Weighted average remaining recognition period (years)	3 years 2 months 1 day

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net income	$ 1,293	$ 3,841	$ 3,868	$ 7,487	$ 3,998	$ 1,630	$ 1,358	$ 1,667	$ 16,489	$ 8,653	$ 7,227
Average number of common shares outstanding (shares)									26,849,253	27,464,996	28,460,077
Less: Average unvested restricted stock awards (shares)									(851,779)	(957,364)	(231,652)
Less: Average unallocated ESOP shares (shares)									(2,011,652)	(2,087,227)	(2,163,478)
Average number of common shares outstanding used to calculate basic earnings per common share (shares)	24,104,239	23,973,116	23,952,443	23,911,419	23,919,483	24,129,512	24,575,211	25,066,086	23,985,822	24,420,405	26,064,947
Average number of common shares outstanding used to calculate diluted earnings per common share (shares)	24,795,366	24,510,092	24,346,553	24,275,665	24,032,613	24,307,540	24,699,794	25,132,441	24,482,414	24,540,929	26,069,589
Basic earnings per share (dollars per share)	$ 0.05	$ 0.16	$ 0.16	$ 0.31	$ 0.17	$ 0.07	$ 0.06	$ 0.07	$ 0.69	$ 0.35	$ 0.28
Diluted earnings per share (dollars per share)	$ 0.05	$ 0.16	$ 0.16	$ 0.31	$ 0.17	$ 0.07	$ 0.05	$ 0.07	$ 0.67	$ 0.35	$ 0.28
Antidilutive securities excluded from computation of earnings per share (shares)									407,950	2,486,000	2,434,000
Stock Options
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive unvested restricted stock awards (shares)									248,161	0	0
Unvested restricted stock
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive unvested restricted stock awards (shares)									248,431	120,524	4,642

Other Commitments and Conting89

Other Commitments and Contingencies - Credit Related Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Commitments to originate loans
Other Commitments [Line Items]
Financial instruments with off-balance-sheet risk	$ 66,020	$ 51,622
Letters of credit
Other Commitments [Line Items]
Financial instruments with off-balance-sheet risk	6,314	3,277
Undisbursed construction loans
Other Commitments [Line Items]
Financial instruments with off-balance-sheet risk	82,177	96,169
Commercial Business
Other Commitments [Line Items]
Financial instruments with off-balance-sheet risk	203,631	164,185
Home equity
Other Commitments [Line Items]
Financial instruments with off-balance-sheet risk	73,369	55,344
Consumer
Other Commitments [Line Items]
Financial instruments with off-balance-sheet risk	$ 15,819	$ 15,995

Other Commitments and Conting90

Other Commitments and Contingencies - Operating Lease Commitments (Details) $ in Thousands	Dec. 31, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,018	$ 2,698
2,019	2,490
2,020	2,409
2,021	2,278
2,022	2,286
Thereafter	9,640
Total future minimum payments due	$ 21,801

Other Commitments and Conting91

Other Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	Jan. 01, 2014	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Commitments [Line Items]
Operating leases, rental expense		$ 3,000	$ 2,200	$ 1,600
Renewal term		30 years
Chief Executive Officer
Other Commitments [Line Items]
Employment agreement, initial term (in years)		3 years
Employment agreement, automatic extension period (in years)		1 year
President
Other Commitments [Line Items]
Employment agreement, initial term (in years)		3 years
Employment agreement, automatic extension period (in years)		1 year
Boston Waterfront Music Venue Naming Rights Agreement
Other Commitments [Line Items]
Contractual obligation, period	10 years
Other commitment contractual obligation	$ 390	$ 454	$ 430	$ 410
Contractual obligation, annual increase (percentage)	5.00%

On Balance Sheet Derivative I92

On Balance Sheet Derivative Instruments and Hedging Activities - Derivative Financial Instruments Not Designated as Hedging Instruments (Details) - Not Designated as Hedging Instrument - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Derivative Asset, notional amount	$ 610,077	$ 435,353
Derivative Asset, fair value	8,766	9,024
Derivative Liability, notional amount	636,681	452,533
Derivative Liability, fair value	8,785	8,988
Interest Rate Swap
Derivatives, Fair Value [Line Items]
Derivative Asset, notional amount	582,388	419,488
Derivative Asset, fair value	8,741	9,016
Derivative Liability, notional amount	582,388	419,488
Derivative Liability, fair value	8,741	8,932
Other Contract
Derivatives, Fair Value [Line Items]
Derivative Asset, notional amount	27,689	15,865
Derivative Asset, fair value	25	8
Derivative Liability, notional amount	54,293	33,045
Derivative Liability, fair value	$ 44	$ 56

On Balance Sheet Derivative I93

On Balance Sheet Derivative Instruments and Hedging Activities - Additional Information (Details) - Not Designated as Hedging Instrument - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Notional amount	$ 610,077	$ 435,353
Notional amount	636,681	452,533
Derivative Gains, fair value	8,766	9,024
Derivative Losses, fair value	8,785	8,988
Mortgage loan commitments
Derivative [Line Items]
Notional amount	16,400	6,800
Derivative Gains, fair value	210
Derivative Losses, fair value	36
Forward loan sale commitments
Derivative [Line Items]
Notional amount	25,300	$ 9,500
Derivative Gains, fair value	22
Derivative Losses, fair value	$ 69

On Balance Sheet Derivative I94

On Balance Sheet Derivative Instruments and Hedging Activities - Summary of Fair Value and Location for Rate-Lock and Forward Loan Sale Commitments (Details) - Not Designated as Hedging Instrument - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Derivative assets	$ 8,766	$ 9,024
Derivative liabilities	8,785	8,988
Mortgage Banking Derivatives
Derivative [Line Items]
Derivative assets	232	126
Derivative liabilities	105	77
Mortgage loan commitments
Derivative [Line Items]
Derivative assets	210
Derivative liabilities	36
Forward loan sale commitments
Derivative [Line Items]
Derivative assets	22
Derivative liabilities	$ 69
Other Assets | Mortgage loan commitments
Derivative [Line Items]
Derivative assets		111
Other Assets | Forward loan sale commitments
Derivative [Line Items]
Derivative assets		15
Other Liabilities | Mortgage loan commitments
Derivative [Line Items]
Derivative liabilities		3
Other Liabilities | Forward loan sale commitments
Derivative [Line Items]
Derivative liabilities		$ 74

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets
Marketable equity securities	$ 9,720	$ 43,168
Debt securities		161,668
Recurring
Assets
Marketable equity securities	9,720	43,168
Debt securities		161,668
Total assets	18,718	213,986
Liabilities
Derivative liabilities	8,890	9,065
Recurring | Level 1
Assets
Marketable equity securities	9,720	43,168
Debt securities		0
Total assets	9,720	43,168
Liabilities
Derivative liabilities	0	0
Recurring | Level 2
Assets
Marketable equity securities	0	0
Debt securities		161,668
Total assets	8,766	170,692
Liabilities
Derivative liabilities	8,785	8,988
Recurring | Level 3
Assets
Marketable equity securities	0	0
Debt securities		0
Total assets	232	126
Liabilities
Derivative liabilities	105	77
Interest Rate Swap | Level 1
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Interest Rate Swap | Level 2
Assets
Derivative assets	8,766	9,024
Liabilities
Derivative liabilities	8,785	8,988
Interest Rate Swap | Level 3
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Interest Rate Swap | Recurring
Assets
Derivative assets	8,766	9,024
Liabilities
Derivative liabilities	8,785	8,988
Interest Rate Swap | Recurring | Level 1
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Interest Rate Swap | Recurring | Level 2
Assets
Derivative assets	8,766	9,024
Liabilities
Derivative liabilities	8,785	8,988
Interest Rate Swap | Recurring | Level 3
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Forward loan sale commitments | Level 1
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Forward loan sale commitments | Level 2
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Forward loan sale commitments | Level 3
Assets
Derivative assets	22	15
Liabilities
Derivative liabilities	69	74
Forward loan sale commitments | Recurring
Assets
Derivative assets	22	15
Liabilities
Derivative liabilities	69	74
Forward loan sale commitments | Recurring | Level 1
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Forward loan sale commitments | Recurring | Level 2
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Forward loan sale commitments | Recurring | Level 3
Assets
Derivative assets	22	15
Liabilities
Derivative liabilities	69	74
Mortgage loan commitments | Level 1
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Mortgage loan commitments | Level 2
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Mortgage loan commitments | Level 3
Assets
Derivative assets	210	111
Liabilities
Derivative liabilities	36	3
Mortgage loan commitments | Recurring
Assets
Derivative assets	210	111
Liabilities
Derivative liabilities	36	3
Mortgage loan commitments | Recurring | Level 1
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Mortgage loan commitments | Recurring | Level 2
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Mortgage loan commitments | Recurring | Level 3
Assets
Derivative assets	210	111
Liabilities
Derivative liabilities	$ 36	$ 3

Other Comprehensive Income - Co

Other Comprehensive Income - Components of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	$ (1,453)	$ (4,069)
Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gain (loss)	(2,694)	(3,482)
Tax effect	757	1,270
Net-of-tax amount	(1,937)	(2,212)
Stranded tax effect related to the Act (see Note 2)	157	0
Accumulated other comprehensive loss	(1,780)	(2,212)
Available-for-sale Securities | Accumulated Net Investment Gain (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gain (loss)	283	(3,087)
Tax effect	(107)	1,007
Net-of-tax amount	176	(2,080)
Stranded tax effect related to the Act (see Note 2)	(33)	0
Accumulated other comprehensive loss	143	(2,080)
Held-to-maturity Securities | Accumulated Net Investment Gain (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized gain (loss)	250	337
Tax effect	(59)	(114)
Net-of-tax amount	191	223
Stranded tax effect related to the Act (see Note 2)	(7)	0
Accumulated other comprehensive loss	$ 184	$ 223

Fair Value Measurements - Ass97

Fair Value Measurements - Assets and Liabilities Measure at Fair Value on a Nonrecurring Basis (Details) - Nonrecurring - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	$ (5)	$ (2,911)	$ (404)
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	2,214	136
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	$ 0	$ 0

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Fair Value, Balance Sheet Grouping (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financial assets:
Securities available for sale	$ 9,720	$ 204,836
Securities held to maturity	303,716	201,027
Carrying Amount
Financial assets:
Cash and cash equivalents	46,167	30,496
Securities available for sale	9,720	204,836
Securities held to maturity	303,716	201,027
Federal Home Loan Bank stock	12,105	13,352
Loans and loans held for sale, net	2,195,139	1,915,632
Accrued interest receivable	6,438	6,057
Financial liabilities:
Deposits	2,039,869	1,808,687
Borrowings	205,000	251,000
Estimate of Fair Value Measurement
Financial assets:
Cash and cash equivalents	46,167	30,496
Securities available for sale	9,720	204,836
Securities held to maturity	299,114	198,093
Federal Home Loan Bank stock	12,105	13,352
Loans and loans held for sale, net	2,174,871	1,903,978
Accrued interest receivable	6,438	6,057
Financial liabilities:
Deposits	2,036,150	1,808,629
Borrowings	203,913	250,648
Level 1
Financial assets:
Cash and cash equivalents	46,167	30,496
Securities available for sale	9,720	43,168
Securities held to maturity	0	0
Federal Home Loan Bank stock	0	0
Loans and loans held for sale, net	0	0
Accrued interest receivable	0	0
Financial liabilities:
Deposits	0	0
Borrowings	0	0
Level 2
Financial assets:
Cash and cash equivalents	0	0
Securities available for sale	0	161,668
Securities held to maturity	299,114	198,093
Federal Home Loan Bank stock	0	0
Loans and loans held for sale, net	0	0
Accrued interest receivable	0	0
Financial liabilities:
Deposits	0	0
Borrowings	203,913	250,648
Level 3
Financial assets:
Cash and cash equivalents	0	0
Securities available for sale	0	0
Securities held to maturity	0	0
Federal Home Loan Bank stock	12,105	13,352
Loans and loans held for sale, net	2,174,871	1,903,978
Accrued interest receivable	6,438	6,057
Financial liabilities:
Deposits	2,036,150	1,808,629
Borrowings	0	0
Interest Rate Swap | Carrying Amount
Financial liabilities:
Derivative assets	8,766	9,024
Derivative liabilities	8,785	8,988
Interest Rate Swap | Estimate of Fair Value Measurement
Financial liabilities:
Derivative assets	8,766	9,024
Derivative liabilities	8,785	8,988
Interest Rate Swap | Level 1
Financial liabilities:
Derivative assets	0	0
Derivative liabilities	0	0
Interest Rate Swap | Level 2
Financial liabilities:
Derivative assets	8,766	9,024
Derivative liabilities	8,785	8,988
Interest Rate Swap | Level 3
Financial liabilities:
Derivative assets	0	0
Derivative liabilities	0	0
Forward loan sale commitments | Carrying Amount
Financial liabilities:
Derivative assets	22	15
Derivative liabilities	69	74
Forward loan sale commitments | Estimate of Fair Value Measurement
Financial liabilities:
Derivative assets	22	15
Derivative liabilities	69	74
Forward loan sale commitments | Level 1
Financial liabilities:
Derivative assets	0	0
Derivative liabilities	0	0
Forward loan sale commitments | Level 2
Financial liabilities:
Derivative assets	0	0
Derivative liabilities	0	0
Forward loan sale commitments | Level 3
Financial liabilities:
Derivative assets	22	15
Derivative liabilities	69	74
Mortgage loan commitments | Carrying Amount
Financial liabilities:
Derivative assets	210	111
Derivative liabilities	36	3
Mortgage loan commitments | Estimate of Fair Value Measurement
Financial liabilities:
Derivative assets	210	111
Derivative liabilities	36	3
Mortgage loan commitments | Level 1
Financial liabilities:
Derivative assets	0	0
Derivative liabilities	0	0
Mortgage loan commitments | Level 2
Financial liabilities:
Derivative assets	0	0
Derivative liabilities	0	0
Mortgage loan commitments | Level 3
Financial liabilities:
Derivative assets	210	111
Derivative liabilities	$ 36	$ 3

Other Comprehensive Income - Ad

Other Comprehensive Income - Additional Information (Details) $ in Thousands	Dec. 31, 2017USD ($)
Equity [Abstract]
Actuarial loss expected to be included in AOCI	$ 266

Condensed Financial Statemen100

Condensed Financial Statements of Parent Company - Condensed Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets [Abstract]
Total cash and cash equivalents	$ 46,167	$ 30,496
Other assets	24,867	23,537
Assets	2,668,520	2,469,692
Liabilities and Equity [Abstract]
Accrued expenses	25,845	23,098
Stockholders' equity	397,806	386,907	$ 398,829	$ 411,606
Total liabilities and stockholders' equity	2,668,520	2,469,692
Parent Company
Assets [Abstract]
Cash balances at Blue Hills Bank	42,111	66,326
Total cash and cash equivalents	42,111	66,326
Investment in Blue Hills Bank	328,740	303,036
Investment in Blue Hills Funding Corp.	26,417	25,165
Other assets	21,146	13,499
Assets	418,414	408,026
Liabilities and Equity [Abstract]
Liability to ESOP	20,533	20,995
Accrued expenses	75	124
Stockholders' equity	397,806	386,907
Total liabilities and stockholders' equity	$ 418,414	$ 408,026

Condensed Financial Statemen101

Condensed Financial Statements of Parent Company - Condensed Statements of Net Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Income Statements, Captions [Line Items]
Loss before income taxes and equity in undistributed net income of subsidiaries									$ 27,715	$ 12,458	$ 10,064
Applicable income tax benefit	$ 4,565	$ 2,342	$ 2,566	$ 1,753	$ 1,323	$ 891	$ 721	$ 870	11,226	3,805	2,837
Net income	$ 1,293	$ 3,841	$ 3,868	$ 7,487	$ 3,998	$ 1,630	$ 1,358	$ 1,667	16,489	8,653	7,227
Parent Company
Condensed Income Statements, Captions [Line Items]
Operating expenses									2,105	2,478	1,860
Loss before income taxes and equity in undistributed net income of subsidiaries									(2,105)	(2,478)	(1,860)
Applicable income tax benefit									(451)	(758)	(1,112)
Loss before equity in income of subsidiaries									(1,654)	(1,720)	(748)
Equity in undistributed net income of subsidiaries									18,143	10,373	7,975
Net income									$ 16,489	$ 8,653	$ 7,227

Condensed Financial Statemen102

Condensed Financial Statements of Parent Company - Condensed Statement of Cash Flow (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income	$ 1,293	$ 3,841	$ 3,868	$ 7,487	$ 3,998	$ 1,630	$ 1,358	$ 1,667	$ 16,489	$ 8,653	$ 7,227
Excess tax benefit from deferred and stock based compensation									0	105	166
Net change in other assets									(2,545)	(3,477)	(1,153)
Net change in other liabilities									2,882	809	(8,661)
Net cash provided by operating activities									19,696	17,669	6,555
Cash flows from investing activities:
Net cash used in investing activities									(174,087)	(358,512)	(424,944)
Cash flows from financing activities:
Repurchase of common stock									0	(24,432)	(13,121)
Share redemption for tax withholdings on deferred compensation obligation									0	0	(439)
Proceeds from exercise of stock options									243	40	0
Net cash provided by financing activities									170,062	338,041	391,541
Net change in cash and cash equivalents									15,671	(2,802)	(26,848)
Cash and cash equivalents at beginning of year				30,496				33,298	30,496	33,298	60,146
Cash and cash equivalents at end of year	46,167				30,496				46,167	30,496	33,298
Parent Company
Cash flows from operating activities:
Net income									16,489	8,653	7,227
Equity in undistributed net income of subsidiaries									(18,143)	(10,373)	(7,975)
Excess tax benefit from deferred and stock based compensation									0	(105)	(166)
Net change in other assets									(1,164)	11,625	(1,157)
Net change in other liabilities									(49)	97	(241)
Net cash provided by operating activities									(2,867)	9,897	(2,312)
Cash flows from investing activities:
Investment in Blue Hills Bank									(6,228)	(16,844)	(3,929)
Net cash used in investing activities									(6,228)	(16,844)	(3,929)
Cash flows from financing activities:
Excess tax benefit from deferred and stock based compensation									0	105	166
Repurchase of common stock									0	(24,432)	13,121
Share redemption for tax withholdings on deferred compensation obligation									(983)	(730)	(439)
Proceeds from exercise of stock options									243	40	0
Common and preferred stock dividends paid									(14,380)	(2,675)	(1,032)
Net cash provided by financing activities									(15,120)	(27,692)	(14,426)
Net change in cash and cash equivalents									(24,215)	(34,639)	(20,667)
Cash and cash equivalents at beginning of year				$ 66,326				$ 100,965	66,326	100,965	121,632
Cash and cash equivalents at end of year	$ 42,111				$ 66,326				$ 42,111	$ 66,326	$ 100,965

Selected Quarterly Financial103

Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Interest and dividend income	$ 22,875	$ 21,545	$ 20,574	$ 19,781	$ 19,434	$ 17,685	$ 16,356	$ 16,063	$ 84,775	$ 69,538	$ 58,301
Interest expense	5,081	4,591	4,166	3,900	3,484	3,190	3,040	2,862	17,738	12,576	8,744
Net interest and dividend income	17,794	16,954	16,408	15,881	15,950	14,495	13,316	13,201	67,037	56,962	49,557
Provision for loan losses	681	242	1,118	57	927	2,872	1,113	(27)	2,098	4,885	4,090
Other noninterest income	2,930	2,826	3,582	1,891	3,509	3,834	2,147	1,621
Realized securities gains (losses), net	0	0	928	(1,022)	298	298	664	(244)
Gain on exchange of investment in Northeast Retirement Services	0	0	0	5,947	0	0	0	0	5,947	0	0
Total noninterest income	2,930	2,826	4,510	6,816	3,807	4,132	2,811	1,377	17,082	12,127	8,679
Total noninterest expense	14,185	13,355	13,366	13,400	13,509	13,234	12,935	12,068	54,306	51,746	44,082
Provision for income taxes	4,565	2,342	2,566	1,753	1,323	891	721	870	11,226	3,805	2,837
Net income	$ 1,293	$ 3,841	$ 3,868	$ 7,487	$ 3,998	$ 1,630	$ 1,358	$ 1,667	$ 16,489	$ 8,653	$ 7,227
Basic earnings per share (dollars per share)	$ 0.05	$ 0.16	$ 0.16	$ 0.31	$ 0.17	$ 0.07	$ 0.06	$ 0.07	$ 0.69	$ 0.35	$ 0.28
Diluted earnings per share (dollars per share)	$ 0.05	$ 0.16	$ 0.16	$ 0.31	$ 0.17	$ 0.07	$ 0.05	$ 0.07	$ 0.67	$ 0.35	$ 0.28
Weighted average common shares (basic) (shares)	24,104,239	23,973,116	23,952,443	23,911,419	23,919,483	24,129,512	24,575,211	25,066,086	23,985,822	24,420,405	26,064,947
Weighted average common shares (diluted) (shares)	24,795,366	24,510,092	24,346,553	24,275,665	24,032,613	24,307,540	24,699,794	25,132,441	24,482,414	24,540,929	26,069,589