Blue Hills Bancorp (BHBK) 10-Q 8 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information Document	3 Months Ended
	Mar. 31, 2015	8-May-15
Document and Entity Information [Abstract]
Entity Registrant Name	Blue Hills Bancorp, Inc.
Entity Central Index Key	1601545
Current Fiscal Year End Date	-19
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Amendment Flag	FALSE
Entity Common Stock, Shares Outstanding		28,466,813

Consolidated_Balance_Sheets_un

Consolidated Balance Sheets (unaudited) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Assets
Cash and due from banks	$10,045	$15,345
Short-term investments	26,966	44,801
Total cash and cash equivalents	37,011	60,146
Securities available for sale, at fair value	429,551	416,447
Federal Home Loan Bank stock, at cost	11,702	11,702
Loans held for sale	17,681	14,591
Loans, net of allowance for loan losses of $13,238 at March 31, 2015 and $12,973 at December 31, 2014	1,165,767	1,132,914
Premises and equipment, net	18,869	18,788
Accrued interest receivable	4,793	4,433
Goodwill	9,160	9,160
Core deposit intangible	3,795	4,232
Net deferred tax asset	5,172	6,233
Bank-owned life insurance	30,848	30,595
Other assets	23,535	18,907
Assets	1,757,884	1,728,148
Deposits:
Non-interest bearing	126,138	123,392
Interest bearing	1,095,072	1,089,324
Total deposits	1,221,210	1,212,716
Short-term borrowings	70,000	40,000
Long-term debt	35,000	35,000
Accrued expenses and other liabilities	16,730	28,826
Total liabilities	1,342,940	1,316,542
Commitments and contingencies
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; 28,466,813 issued and outstanding)	285	285
Additional paid-in capital	281,094	281,035
Unearned compensation-ESOP	-21,825	-22,014
Retained earnings	151,029	149,723
Accumulated other comprehensive income	4,361	2,577
Total stockholders' equity	414,944	411,606
Liabilities and Equity	$1,757,884	$1,728,148

Consolidated_Balance_Sheets_un1

Consolidated Balance Sheets (unaudited) (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]
Allowance for Loan Losses	$13,238	$12,973
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	28,466,813	28,466,813
Common stock, shares outstanding	28,466,813	28,466,813

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (unaudited) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Interest and dividend income:
Interest and fees on loans	$10,427	$8,051
Interest on securities	2,136	1,937
Dividends	100	166
Other	19	15
Total interest and dividend income	12,682	10,169
Interest expense:
Interest on deposits	1,763	1,351
Interest on borrowings	254	304
Total interest expense	2,017	1,655
Net interest and dividend income	10,665	8,514
Provision for loan losses	279	714
Net interest income, after provision for loan losses	10,386	7,800
Noninterest income:
Deposit account fees	333	291
Interchange and ATM fees	326	285
Mortgage banking	101	68
Loan level derivative income	4	150
Gains on sales of securities available for sale, net	1,318	541
Gains on trading assets, net	0	25
Bank-owned life insurance income	253	249
Miscellaneous	-151	20
Total noninterest income	2,184	1,629
Noninterest expense:
Salaries and employee benefits	5,489	5,129
Occupancy and equipment	1,498	1,601
Data processing	819	605
Professional fees	632	1,159
Advertising	500	301
FDIC deposit insurance	292	178
Directorsb fees	124	150
Amortization of core deposit intangible	437	353
Other general and administrative	835	780
Total noninterest expense	10,626	10,256
Income (loss) before income taxes	1,944	-827
Provision (benefit) for income taxes	638	-428
Net income (loss)	$1,306	($399)
Earnings per common share:
Basic (dollars per share)	$0.05
Diluted (dollars per share)	$0.05
Weighted average shares outstanding:
Basic (shares)	26,274,738
Diluted (shares)	26,274,738

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (unaudited) Statement (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income (loss)	$1,306		($399)
Securities available for sale:
Change in unrealized holding gains	4,162		4,173
Reclassification adjustment for net gains realized in net income	-1,318	[1]	-541	[1]
Net change in unrealized gains	2,844		3,632
Tax effect	-1,060		-1,398
Net-of-tax amount	1,784		2,234
Other comprehensive income	1,784		2,234
Comprehensive income	$3,090		$1,835
[1]	Amounts are included in gains on sales of securities available for sale, net, in noninterest income in the consolidated statements of operations. Income tax expense associated with the reclassification adjustments for the three months ended MarchB 31, 2015 and 2014 was $461,000 and $199,000, respectively.

Consolidated_Statements_of_Com1

Consolidated Statements of Comprehensive Income (unaudited) (Parenthetical) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Reclassification adjustment for net gains realized in net income, tax	$461	$199

Consolidated_Statements_of_Cha

Consolidated Statements of Changes in Stockholders' Equity (unaudited) (USD $)	Total	SBLF Preferred Stock	Common Stock	Additional Paid-in Capital	Unearned Compensation- ESOP	Retained Earnings	Accumulated Other Comprehensive Income
In Thousands, except Share data, unless otherwise specified
Beginning balance at Dec. 31, 2013	$171,534	$18,724	$0	$0	$0	$150,345	$2,465
Beginning balance (shares) at Dec. 31, 2013			0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	1,835					-399	2,234
Preferred stock dividends declared	-204					-204
Ending balance at Mar. 31, 2014	173,165	18,724	0	0	0	149,742	4,699
Ending balance (shares) at Mar. 31, 2014			0
Beginning balance at Dec. 31, 2014	411,606	0	285	281,035	-22,014	149,723	2,577
Beginning balance (shares) at Dec. 31, 2014			28,466,813
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	3,090					1,306	1,784
Preferred stock dividends declared	0
ESOP shares committed to be released	248			59	189
Ending balance at Mar. 31, 2015	$414,944	$0	$285	$281,094	($21,825)	$151,029	$4,361
Ending balance (shares) at Mar. 31, 2015			28,466,813

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (unaudited) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net income (loss)	$1,306	($399)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Provision for loan losses	279	714
Net amortization of securities available for sale	959	486
Gains on sales of securities available for sale, net	-1,318	-541
Proceeds from sale of loans	7,192	2,236
Loans originated for sale	-5,795	-1,424
Gains on sale of loans, net	-115	-47
Loss on sale of jumbo residential portfolio loans	22	0
Net amortization of deferred loan origination costs and discounts	-97	7
Depreciation and amortization	430	306
Amortization of core deposit intangible	437	353
Bank-owned life insurance income	-253	-249
ESOP expense	248	0
Net change in:
Trading assets	0	750
Accrued interest receivable	-360	688
Other assets	-4,628	-1,870
Accrued expenses and other liabilities	-12,096	1,235
Net cash provided by (used in) operating activities	-13,789	2,245
Activity in securities available for sale:
Purchases	-90,303	-61,575
Sales	68,042	48,573
Maturities/calls	5,100	6,474
Principal paydowns	7,261	6,560
Loan originations and purchases net of paydowns	-43,002	-52,873
Proceeds from jumbo residential portfolio loan sale	5,573	0
Net purchases of premises and equipment	-511	-347
Purchases of FHLBB stock	0	-480
Cash provided by business combination, net of purchase price	0	151,587
Net cash provided by (used in) investing activities	-47,840	97,919
Cash flows from financing activities:
Net change in deposits, excluding brokered deposits	7,669	-2,145
Net change in brokered deposits	825	-70,918
Net change in short-term borrowings	30,000	-20,000
Preferred stock dividends paid	0	-204
Net cash provided by (used in) financing activities	38,494	-93,267
Net change in cash and cash equivalents	-23,135	6,897
Cash and cash equivalents at beginning of year	60,146	40,316
Cash and cash equivalents at end of year	37,011	47,213
Supplementary information:
Interest paid	2,025	1,652
Income taxes paid, net of refunds	1,340	82
Preferred stock dividends declared	0	204
Fair value of non-cash assets acquired	0	123,755
Fair value of liabilities assumed	0	275,342
Portfolio loans transferred to loans held for sale designation	$4,372	$0

Basis_of_Presentation_and_Cons

Basis of Presentation and Consolidation	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Consolidation	BASIS OF PRESENTATION AND CONSOLIDATION
	Conversion
	Blue Hills Bancorp, Inc. (the “Company”) is a Maryland corporation formed in February 2014 for the purpose of becoming the holding company for Blue Hills Bank (the “Bank”) concurrent with the conversion of Hyde Park Bancorp, MHC from the mutual holding company to the stock holding company form of organization on July 21, 2014. In connection with the conversion, the Bank became a wholly-owned subsidiary of the Company and the Company sold 27,772,500 shares of its common stock, representing the adjusted maximum of the offering range, at $10.00 per share, for gross offering proceeds of approximately $277,725,000, including the sale of 2,277,345 shares to the employee stock ownership plan (“ESOP”) for $22,773,450. The purchase of common stock by the ESOP was financed by a loan from Blue Hills Funding Corporation, a subsidiary of the Company. Upon the completion of the conversion, Hyde Park Bancorp, MHC and the Bank’s former Massachusetts chartered mid-tier holding company, Hyde Park Bancorp, Inc., ceased to exist.
	In connection with the plan of conversion, the Company established the Blue Hills Bank Foundation (the “Foundation”). The Foundation was funded with $7.0 million, including 694,313 shares of the Company’s common stock and $57,000 in cash, which was recorded as an expense by the Company in July 2014. The Company anticipates the contribution will be deductible for federal income tax purposes.
	Basis of Presentation
	The accompanying unaudited interim consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, Blue Hills Funding Corporation and the Bank, the principal operating entity, and its wholly-owned subsidiaries, HP Security Corporation, which is a Massachusetts security corporation, and 1196 Corporation, which holds a restricted stock. All significant intercompany balances and transactions have been eliminated in consolidation.
	The unaudited consolidated financial statements of the Company presented herein have been prepared in accordance with U.S. Generally Accepted Accounting Principles (“GAAP”) for interim financial information and pursuant to the rules of the Securities and Exchange Commission ("SEC") for quarterly reports on Form 10-Q and Article 8 of Regulation S-X and do not include all of the information and note disclosures required by GAAP for a complete set of financial statements. In the opinion of management, all adjustments (consisting of normal recurring adjustments) and disclosures necessary for the fair presentation of the accompanying consolidated financial statements have been included. Interim results are not necessarily reflective of the results of the year. The accompanying unaudited financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto for the year ended December 31, 2014, included in the Company's annual report on Form 10-K.
	In preparing the consolidated financial statements, 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.
	Reclassification
	Certain amounts in the December 31, 2014 consolidated financial statements have been reclassified to conform to the current presentation.
	Loan policies
	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 and any deferred fees and costs on originated and 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 or cost recovery method 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. For portfolios for which the Company had no prior loss experience, the national and state peer group losses for relevant portfolios generally over the years 2006-2014 were used. Charge-off factors are updated at least annually and management assesses them quantitatively on a quarterly basis. 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; however, because of the increase in risk exposures new to the Company, it is the intention of management to maintain an allowance that is prudently commensurate with the growth 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 extrapolated historical loss experience for periods ranging from 2006-2014, adjusted for qualitative and environmental factors including levels/trends in delinquencies; trends in volumes and terms of loans; effects of changes in risk selection and underwriting standards and other changes in lending policies, procedures and practices; experience/ability/depth of lending management and staff; and national and local economic trends and conditions.
	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 regional 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 1st or 2nd 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 and real estate collateral. 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 are adversely impacted by a downturn in the economy as evidenced by increased vacancy rates, which in turn, will 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 auto loans. A significant portion of the used auto loan portfolio is comprised of geographically diverse loans originated by and purchased from a third party, who also provides collection services. While this portfolio has generated minimal charge-offs, the provisions for loan losses reflect management’s estimate of inherent losses based on a review of regional and national historical losses of other institutions with similar portfolios.
	Allocated component
	The allocated component relates to loans that are on the watch list (partially charged-off, non-accruing loans and accruing adversely-rated loans) and are 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 greater than or equal to that which would be provided to a borrower with similar credit risk at the time of restructuring.
	Unallocated component
	An unallocated component is maintained to cover uncertainties that could affect management’s estimate of probable losses. The unallocated component of the allowance reflects the margin of imprecision inherent in the underlying assumptions used in the methodologies for estimating allocated and general reserves in the portfolio.

Securities_Available_for_Sale

Securities Available for Sale	3 Months Ended
	Mar. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Securities Available for Sale	SECURITIES AVAILABLE FOR SALE
	The amortized cost and estimated fair value of securities available for sale, with gross unrealized gains and losses, follows:
		Amortized			Gross		Gross			Fair
		Cost			Unrealized		Unrealized			Value
					Gains		Losses
		(In thousands)
	31-Mar-15
	Debt securities:
	U.S. Treasury	$	598		$	70	$	—		$	668
	Government-sponsored enterprises	26,164			223		—			26,387
	Government-sponsored mortgage-backed and collateralized mortgage obligations	154,342			1,623		(44		)	155,921
	Other mortgage- and asset-backed securities:
	Privately issued commercial mortgage-backed securities	17,532			28		(105		)	17,455
	SBA asset-backed securities	11,565			118		(9		)	11,674
	Other asset-backed securities	10,568			13		(49		)	10,532
	Total other mortgage- and asset-backed securities	39,665			159		(163		)	39,661
	State and political subdivisions	16,258			518		(1		)	16,775
	Financial services:
	Banks	19,446			534		—			19,980
	Diversified financials	23,913			654		(5		)	24,562
	Insurance and REITs	15,932			197		(20		)	16,109
	Total financial services	59,291			1,385		(25		)	60,651
	Other corporate:
	Industrials	48,427			1,025		(36		)	49,416
	Utilities	31,525			580		(69		)	32,036
	Total other corporate	79,952			1,605		(105		)	81,452
	Total debt securities	376,270			5,583		(338		)	381,515
	Marketable equity securities:
	Mutual funds:
	Global equity	5,000			754		—			5,754
	Domestic community	3,216			112		(3		)	3,325
	Global asset allocation	36,956			2,019		(18		)	38,957
	Total marketable equity securities	45,172			2,885		(21		)	48,036
	Total securities available for sale	$	421,442		$	8,468	$	(359	)	$	429,551
		Amortized			Gross		Gross			Fair
		Cost			Unrealized		Unrealized			Value
					Gains		Losses
		(In thousands)
	31-Dec-14
	Debt securities:
	U.S. Treasury	$	13,037		$	182	$	—		$	13,219
	Government-sponsored enterprises	26,335			131		(29		)	26,437
	Government-sponsored mortgage-backed and collateralized mortgage obligations	160,091			756		(294		)	160,553
	Other mortgage- and asset-backed securities:
	Privately issued commercial mortgage-backed securities	22,100			30		(201		)	21,929
	SBA asset-backed securities	27,765			308		(27		)	28,046
	Other asset-backed securities	16,235			—		(43		)	16,192
	Total other mortgage- and asset-backed securities	66,100			338		(271		)	66,167
	State and political subdivisions	15,619			567		(3		)	16,183
	Financial services:
	Banks	12,364			531		(6		)	12,889
	Diversified financials	15,796			354		(18		)	16,132
	Insurance and REITs	9,387			138		(9		)	9,516
	Total financial services	37,547			1,023		(33		)	38,537
	Other corporate:
	Industrials	34,408			681		(54		)	35,035
	Utilities	16,873			265		(120		)	17,018
	Total other corporate	51,281			946		(174		)	52,053
	Total debt securities	370,010			3,943		(804		)	373,149
	Marketable equity securities:
	Mutual funds:
	Global equity	5,000			623		—			5,623
	Domestic community	3,216			86		(5		)	3,297
	Global asset allocation	32,956			1,498		(76		)	34,378
Total marketable equity securities	41,172			2,207		(81		)	43,298
Total securities available for sale	$	411,182		$	6,150	$	(885	)	$	416,447
The amortized cost and estimated fair value of debt securities by contractual maturity at March 31, 2015 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.
	Amortized			Fair
	Cost			Value
	(In thousands)
Within 1 year	$	792		$	794
After 1 year through 5 years	93,391			94,898
After 5 years through 10 years	77,696			79,338
After 10 years	10,384			10,903
	182,263			185,933
Mortgage- and asset-backed securities and collateralized mortgage obligations	194,007			195,582
	$	376,270		$	381,515
The Company continually reviews investment securities for the existence of other-than-temporary impairment ("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 available for sale with gross unrealized losses aggregated by investment category and length of time that individual securities have been in a continuous loss position, follows:
	Less Than Twelve Months					More Than Twelve Months
	Gross			Fair		Gross			Fair
	Unrealized			Value		Unrealized			Value
	Losses					Losses
	(In thousands)
31-Mar-15
Debt securities:
Government-sponsored mortgage-backed and collateralized mortgage obligations	$	(37	)	$	12,463	$	(7	)	$	239
Other mortgage- and asset-backed securities:
Privately issued commercial mortgage- backed securities	(30		)	6,477		(75		)	7,872
SBA asset-backed securities	(9		)	5,387		—			—
Other asset-backed securities	(49		)	5,931		—			—
Total other mortgage- and asset-backed securities	(88		)	17,795		(75		)	7,872
State and political subdivisions	(1		)	990		—			—
Financial services:
Diversified financials	(5		)	659		—			—
Insurance and REITs	(20		)	1,051		—			—
Total financial services	(25		)	1,710		—			—
Other corporate:
Industrials	(36		)	4,975		—			—
Utilities	(69		)	5,273		—			—
Total other corporate	(105		)	10,248		—			—
Total debt securities	(256		)	43,206		(82		)	8,111
Marketable equity securities:
Mutual funds:
Domestic community	—			—		(3		)	463
Global asset allocation	(18		)	3,982		—			—
Total marketable equity securities	(18		)	3,982		(3		)	463
Total temporarily impaired securities	$	(274	)	$	47,188	$	(85	)	$	8,574
	Less Than Twelve Months					More Than Twelve Months
	Gross			Fair		Gross			Fair
	Unrealized			Value		Unrealized			Value
	Losses					Losses
	(In thousands)
31-Dec-14
Debt securities:
Government-sponsored enterprises	$	(12	)	$	5,932	$	(17	)	$	1,080
Government-sponsored mortgage-backed and collateralized mortgage obligations	(190		)	93,364		(104		)	8,425
Other mortgage- and asset-backed securities:
Privately issued commercial mortgage- backed securities	(69		)	9,412		(132		)	8,759
SBA asset-backed securities	(27		)	5,529		—			—
Other asset-backed securities	(43		)	16,192		—			—
Total other mortgage- and asset-backed securities	(139		)	31,133		(132		)	8,759
State and political subdivisions	(3		)	1,955					—
Financial services:
Banks	(6		)	2,907		—			—
Diversified financials	(18		)	7,676		—			—
Insurance and REITs	(9		)	4,177		—			—
Total financial services	(33		)	14,760		—			—
Other corporate:
Industrials	(54		)	9,575		—			—
Utilities	(120		)	7,291		—			—
Total other corporate	(174		)	16,866		—			—
Total debt securities	(551		)	164,010		(253		)	18,264
Marketable equity securities:
Mutual funds:
Domestic community	—			—		(5		)	462
Diversified bonds	(76		)	7,057		—			—
Total marketable equity securities	(76		)	7,057		(5		)	462
Total temporarily impaired securities	$	(627	)	$	171,067	$	(258	)	$	18,726
At March 31, 2015, multiple debt securities have unrealized losses with aggregate depreciation of less than 1% from the Company’s amortized cost basis. The unrealized losses were primarily caused by interest rate fluctuations. A significant portion of these investments are guaranteed by U.S. Government sponsored enterprises. 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 March 31, 2015.
At March 31, 2015, the Company had two mutual funds with an unrealized loss of $21,000, or less than 1% depreciation from 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_Lo

Loans and The Allowance for Loan Loss	3 Months Ended
	Mar. 31, 2015
Receivables [Abstract]
Loans and Allowance for Loan Loss	LOANS AND THE ALLOWANCE FOR LOAN LOSS
	A summary of the balances of loans follows:
		March 31,				December 31,
		2015				2014
		(In thousands)
	Real estate:
	1-4 family residential	$	461,903			$	460,273
	Home equity	63,445				61,750
	Commercial real estate	408,003				387,807
	Construction	59,854				53,606
		993,205				963,436
	Commercial business	154,647				151,823
	Consumer	31,999				31,778
	Total loans	1,179,851				1,147,037
	Allowance for loan losses	(13,238		)		(12,973		)
	Discount and fair value adjustments on purchased loans	(3,614		)		(3,850		)
	Deferred loan costs and fees, net	2,768				2,700
	Loans, net	$	1,165,767			$	1,132,914
	Activity in the allowance for loan losses for the three months months ended March 31, 2015 and 2014 and allocation of the allowance to loan segments as of March 31, 2015 and December 31, 2014 follows:
		1-4 Family				Home				Commercial		Construction		Commercial			Consumer			Unallocated			Total
		Residential				Equity				Real Estate				Business
		(In thousands)
	Three Months Ended March 31, 2015
	Allowance at December 31, 2014	$	3,222			$	340			$	3,551	$	1,056	$	3,410		$	736		$	658		$	12,973
	Provision (credit) for loan losses	(7		)		40				171		120		(78		)	25			8			279
	Loans charged-off	—				—				—		—		—			(14		)	—			(14		)
	Recoveries	—				—				—		—		—			—			—			—
	Allowance at March 31, 2015	$	3,215			$	380			$	3,722	$	1,176	$	3,332		$	747		$	666		$	13,238
	Three Months Ended March 31, 2014
	Allowance at December 31, 2013	$	2,835			$	247			$	2,608	$	303	$	2,416		$	574		$	688		$	9,671
	Provision (credit) for loan losses	70				21				320		111		173			49			(30		)	714
	Loans charged-off	(18		)		—				—		—		—			(21		)	—			(39		)
	Recoveries	—				—				—		—		—			—			—			—
	Allowance at March 31, 2014	$	2,887			$	268			$	2,928	$	414	$	2,589		$	602		$	658		$	10,346
	Additional information pertaining to the allowance for loan losses at March 31, 2015 and December 31, 2014 is as follows:
		1-4 Family				Home				Commercial		Construction		Commercial			Consumer			Unallocated			Total
		Residential				Equity				Real Estate				Business
		(In thousands)
	March 31, 2015
	Allowance related to impaired loans	$	—			$	—			$	—	$	—	$	—		$	—		$	—		$	—
	Allowance related to non-impaired loans	3,215				380				3,722		1,176		3,332			747			666			13,238
	Total allowance for loan losses	$	3,215			$	380			$	3,722	$	1,176	$	3,332		$	747		$	666		$	13,238
	Impaired loans	$	4,694			$	578			$	—	$	—	$	—		$	30		$	—		$	5,302
	Non-impaired loans	457,209				62,867				408,003		59,854		154,647			31,969			—			1,174,549
	Total loans	$	461,903			$	63,445			$	408,003	$	59,854	$	154,647		$	31,999		$	—		$	1,179,851
	December 31, 2014
	Allowance related to impaired loans	$	—			$	—			$	—	$	—	$	—		$	—		$	—		$	—
	Allowance related to non-impaired loans	3,222				340				3,551		1,056		3,410			736			658			12,973
	Total allowance for loan losses	$	3,222			$	340			$	3,551	$	1,056	$	3,410		$	736		$	658		$	12,973
	Impaired loans	$	4,419			$	578			—		$	—	$	—		$	27		$	—		$	5,024
	Non-impaired loans	455,854				61,172				387,807		53,606		151,823			31,751			—			1,142,013
	Total loans	$	460,273			$	61,750			$	387,807	$	53,606	$	151,823		$	31,778		$	—		$	1,147,037
	The following is a summary of past due and non-accrual loans, by loan class, at March 31, 2015 and December 31, 2014:
		30-59 Days				60-89 Days				Past Due 90		Total		Loans on
		Past Due				Past Due				Days or More		Past Due		Non-accrual
		(In thousands)
	March 31, 2015
	Real estate:
	1-4 family residential	$	1,131			$	464			$	774	$	2,369	$	4,158
	Home equity	1,967				18				480		2,465		578
	Consumer	518				15				10		543		30
	Total	$	3,616			$	497			$	1,264	$	5,377	$	4,766
	December 31, 2014
	Real estate:
1-4 family residential	$	3,137			$	522			$	1,370	$	5,029	$	3,876
Home equity	680				—				475		1,155		578
Consumer	217				—				5		222		$	27
Total	$	3,817			$	522			$	1,845	$	6,184	$	4,481
There were no loans past due 90 days or more and still accruing interest at March 31, 2015 and December 31, 2014.
The following is a summary of information pertaining to impaired loans by loan class at the dates indicated:
	Recorded				Unpaid				Related
	Investment				Principal				Allowance
					Balance
March 31, 2015	(In thousands)
Impaired loans without a valuation allowance:
Real estate:
1-4 family residential	$	4,694			$	5,487			$	—
Home equity	578				804				—
Consumer	30				30				—
Total	$	5,302			$	6,321			$	—
December 31, 2014
Impaired loans without a valuation allowance:
Real estate:
1-4 family residential	$	4,419			$	5,211			$	—
Home equity	578				804
Consumer loans	27				25				—
Total	$	5,024			$	6,040			$	—
The following tables set forth information regarding average balances and interest income recognized (all on a cash basis) on impaired loans by class, for the periods indicated:
	Average				Interest
	Recorded				Income
	Investment				Recognized
Three Months Ended March 31, 2015	(In thousands)
Real estate:
1-4 family residential	$	4,557			$	67
Home equity	578				6
Consumer	28				—
Total	$	5,163			$	73
Three Months Ended March 31, 2014
Real estate:
1-4 family residential	$	3,250			$	34
Home Equity	297				4
Commercial business	277				4
Consumer	5				—
Total	$	3,829			$	42
No additional funds are committed to be advanced in connection with impaired loans.
Troubled debt restructurings entered into during the three months ended March 31, 2015 are as follows:
	Number of contracts			Pre-Modification Outstanding Recorded Investment				Post-Modification Outstanding Recorded Investment
Real estate:
1-4 family residential	2			$	469			$	490
During the three months ended March 31, 2015, two residential real estate loans were modified to capitalize past due interest.
There were no troubled debt restructurings recorded during the three months ended March 31, 2014 and there were no troubled debt restructurings that defaulted during the three months ended March 31, 2015 and 2014, for which default was within one year of the restructure date.
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, meet minimum underwriting standards, and 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 assets.
The Company assigns a 6 risk-rating to otherwise performing, satisfactorily collateralized Consumer and Residential loans where the Bank 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. In addition, management 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 March 31, 2015 and December 31, 2014:
	1-4 Family				Home				Commercial		Construction		Commercial			Consumer			Total
	Residential				Equity				Real Estate				Business						Loans
	(In thousands)
March 31, 2015
Loans rated 1 - 6	$	3,361			$	471			$	407,394	$	59,854	$	154,503		$	5		$	625,588
Loans rated 7	3,077				850				609		—		144			—			4,680
Loans rated 8	1,442				—				—		—		—			30			1,472
Loans rated 9	709				—				—		—		—			—			709
Loans rated 10	—				—				—		—		—			—			—
Loans not rated	453,314				62,124				—		—		—			31,964			547,402
	$	461,903			$	63,445			$	408,003	$	59,854	$	154,647		$	31,999		$	1,179,851
December 31, 2014
Loans rated 1 - 6	$	3,381			$	473			$	387,651	$	53,606	$	150,960		$	5		$	596,076
Loans rated 7	3,095				852				156		—		863			—			4,966
Loans rated 8	1,331				—				—		—		—			31			1,362
Loans rated 9	709				—				—		—		—			—			709
Loans rated 10	—				—				—		—		—			—			—
Loans not rated	451,757				60,425				—		—		—			31,742			543,924
	$	460,273			$	61,750			$	387,807	$	53,606	$	151,823		$	31,778		$	1,147,037

Interest_Rate_Swap_Agreements

Interest Rate Swap Agreements	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Interest Rate Swap Agreements	INTEREST RATE SWAP AGREEMENTS
	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 operations.
	The Company did not have derivative fair value hedges or derivative cash flow hedges at March 31, 2015 and December 31, 2014. The table below presents information about derivative financial instruments not designated as hedging instruments at March 31, 2015 and December 31, 2014.
		Derivative Gains				Derivative Losses
		Notional		Fair		Notional		Fair
		Amount		Value		Amount		Value
		(In thousands)
	31-Mar-15
	Economic hedges:
	Commercial loan level interest rate swap agreements	$	197,818	$	7,275	$	197,818	$	7,806
	Other contracts	8,537		11		8,252		103
	Total derivatives	$	206,355	$	7,286	$	206,070	$	7,909
	31-Dec-14
	Economic hedges:
	Commercial loan level interest rate swap agreements	$	202,970	$	5,446	$	202,970	$	5,759
	Other contracts	8,616		8		8,287		83
	Total derivatives	$	211,586	$	5,454	$	211,257	$	5,842
	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.

Deposits

Deposits	3 Months Ended
	Mar. 31, 2015
Banking and Thrift [Abstract]
Deposits	DEPOSITS
	A summary of deposit balances, by type, is as follows:
		March 31,		December 31,
		2015		2014
		(In thousands)
	NOW and demand	$	256,746	$	245,117
	Regular savings	301,932		303,834
	Money market deposits	269,164		280,139
	Brokered money market	23,991		23,166
	Total non-certificate accounts	851,833		852,256
	Term certificates of $100,000 or more	150,668		142,569
	Term certificates less than $100,000	160,004		159,186
	Brokered certificates of deposit	58,705		58,705
	Total certificate accounts	369,377		360,460
	Total deposits	$	1,221,210	$	1,212,716
	At March 31, 2015, the scheduled maturities of term certificate accounts, including brokered deposits, are as follows:
		Amount		Weighted
				Average
				Rate
		(Dollars in thousands)
	Within 1 year	$	187,831	0.57	%
	1-2 years	64,608		1.27
	2-3 years	49,097		1.27
	3-4 years	8,995		1.22
	4 years and beyond	58,846		1.99
		$	369,377	1.03	%

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2015
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 financial instruments. 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 instrument.
	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 available for sale: 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. Treasuries 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: For variable-rate loans that reprice frequently and with no significant change in credit risk, fair values are based on carrying values. Fair values for other types of loans 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.
	Loans held for sale: Fair values are based on commitments in effect from investors or prevailing market prices.
	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 carrying value of short-term borrowings approximates fair value based on the short-term nature of the instruments. The fair values of long-term debt are estimated using discounted cash flow analyses based on the current incremental borrowing rates in the market for similar types of borrowing arrangements.
	Derivative instruments: 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.
	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 March 31, 2015 and December 31, 2014, 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)
	31-Mar-15
	Assets
	Securities available for sale:
	Debt securities	$	668		$	380,847		$	—	$	381,515
	Marketable equity securities	48,036			—			—		48,036
	Derivative assets	—			7,286			—		7,286
	Total assets	$	48,704		$	388,133		$	—	$	436,837
	Liabilities
	Derivative liabilities	$	—		$	7,909		$	—	$	7,909
	31-Dec-14
	Assets
	Securities available for sale:
	Debt securities	13,219			359,930			—		373,149
	Marketable equity securities	43,298			—			—		43,298
	Derivative assets	—			5,454			—		5,454
	Total assets	$	56,517		$	365,384		$	—	$	421,901
	Liabilities
	Derivative liabilities	$	—		$	5,842		$	—	$	5,842
	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 nonrecurring 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. At March 31, 2015, there are no assets measured at fair value on a non-recurring basis. There are no liabilities measured at fair value on a non-recurring basis. The following tables summarize losses and fair value hierarchy applicable to assets measured at fair value on a non-recurring basis:
		At December 31, 2014					Three Months Ended March 31, 2014
		Level 1		Level 2	Level 3		Total Losses
		(In thousands)
	Impaired loans	$—		$—	$120		$18
	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
		Amount			Level 1			Level 2		Level 3		Total
		(In thousands)
	31-Mar-15
	Financial assets:
	Cash and cash equivalents	$	37,011		$	37,011		$	—	$	—	$	37,011
	Securities available for sale	429,551			48,704			380,847		—		429,551
	Federal Home Loan Bank stock	11,702			—			—		11,702		11,702
	Loans and loans held for sale	1,183,448			—			—		1,168,563		1,168,563
	Accrued interest receivable	4,793			—			—		4,793		4,793
	Financial liabilities:
	Deposits	1,221,210			—			—		1,222,086		1,222,086
	Borrowings	105,000			—			106,155		—		106,155
	On-balance sheet derivative financial instruments:
	Interest rate swap agreements:
	Assets	7,286			—			7,286		—		7,286
	Liabilities	7,909			—			7,909		—		7,909
		Carrying			Fair Value
	Amount			Level 1			Level 2		Level 3		Total
	(In thousands)
31-Dec-14
Financial assets:
Cash and cash equivalents	$	60,146		$	60,146		$	—	$	—	$	60,146
Securities available for sale	416,447			56,517			359,930		—		416,447
Federal Home Loan Bank stock	11,702			—			—		11,702		11,702
Loans and loans held for sale	1,147,505			—			—		1,132,024		1,132,024
Accrued interest receivable	4,433			—			—		4,433		4,433
Financial liabilities:
Deposits	1,212,716			—			—		1,214,251		1,214,251
Borrowings	75,000			—			76,074		—		76,074
On-balance sheet derivative financial instruments:
Interest rate swap agreements:
Assets	5,454			—			5,454		—		5,454
Liabilities	5,842			—			5,842		—		5,842

Comprehensive_Income

Comprehensive Income	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Comprehensive Income	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 stockholders' equity on the consolidated balance sheets, such items, along with net income, are components of comprehensive income.
	Changes in accumulated other comprehensive income, by component, follows:
		Three Months ended March 31, 2015
		Securities Available for Sale			Defined Benefit Pension Plan			Total
	Balance at December 31, 2014	$	3,392		$	(815	)	$	2,577
	Other comprehensive income before reclassification	4,162			—			4,162
	Amounts reclassified	(1,318		)	—			(1,318		)
	Tax effects	(1,060		)	—			(1,060		)
	Net current-period other comprehensive income	1,784			—			1,784
	Balance at March 31, 2015	$	5,176		$	(815	)	$	4,361
		Three Months ended March 31, 2014
		Securities Available for Sale			Defined Benefit Pension Plan			Total
	Balance at December 31, 2013	$	1,983		$	482		$	2,465
	Other comprehensive income before reclassification	4,173			—			4,173
	Amounts reclassified	(541		)	—			(541		)
	Tax effects	(1,398		)	—			(1,398		)
	Net current-period other comprehensive income	2,234			—			2,234
	Balance at March 31, 2014	$	4,217		$	482		$	4,699
	The components of accumulated other comprehensive income, included in stockholders' equity, are as follows:
		March 31,			December 31,
		2015			2014
		(In thousands)
	Securities available for sale:
	Net unrealized gain	$	8,109		$	5,265
	Tax effect	(2,933		)	(1,873		)
	Net-of-tax amount	5,176			3,392
	Defined benefit pension plan:
	Unrecognized net actuarial loss	(1,358		)	(1,358		)
	Tax effect	543			543
	Net-of-tax amount	(815		)	(815		)
		$	4,361		$	2,577

Stockholders_Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Stockholders' 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.
	Quantitative measures established by regulation to ensure capital adequacy require minimum ratios of Tier 1 capital to average assets (Leverage Ratio) and common equity Tier 1, Tier 1 and Total capital to risk-weighted assets. These capital guidelines assign risk weights to on- and off-balance sheet items in arriving at total risk-weighted assets. Minimum capital levels are based upon the perceived risk of various asset categories and certain off-balance sheet instruments.
	In July 2013, federal banking regulators approved final rules that implement changes to the regulatory capital framework for U.S. banks. The rules set minimum requirements for both the quantity and quality of capital held by community banking institutions. The final rule includes a new minimum ratio of common equity Tier 1 capital to risk weighted assets of 4.5%, raises the minimum ratio of Tier 1 capital to risk-weighted assets from 4% to 6% and includes a minimum leverage ratio of 4% for all banking organizations. 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 bonus payments to executive officers. The phase-in period for the rules began for the Company on January 1, 2015, with full compliance with all of the final rule’s requirements phased in over a multi-year schedule. The final rules also apply, effective January 1, 2015, consolidated capital requirements to the Company that are not less stringent than those applicable to the Bank.
	As of March 31, 2015, 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 total risk-based, Tier 1 risk-based, Common EquityTier 1risk-based, and Tier 1 leverage ratios as set forth in the following table. There are no conditions or events since that notification that management believes have changed the Bank’s category.
	The Bank’s and the Company’s actual and minimum required capital amounts and ratios as of March 31, 2015 and December 31, 2014 are presented below.
		Actual				Minimum				Minimum
						Capital				To Be Well
						Requirement				Capitalized
		Amount		Ratio		Amount		Ratio		Amount		Ratio
		(Dollars in thousands)
	Blue Hills Bancorp, Inc.:
	31-Mar-15
	Total capital (to risk weighted assets)	$	414,618	30.2	%	$	109,983	8	%	137,749		10	%
	Tier 1 capital (to risk weighted assets)	400,090		29.1		82,487		6		109,983		8
	Common equity Tier 1(to risk weighted assets)	400,090		29.1		61,866		4.5		89,361		6.5
	Tier 1 capital (to average assets)	400,090		23.1		69,229		4		86,535		5
	31-Dec-14
	Total capital (to risk weighted assets)	$	409,545	32.6	%	$	100,513	8	%	N/A		N/A
	Tier 1 capital (to risk weighted assets)	395,615		31.5		50,527		4		N/A		N/A
	Common equity Tier 1(to risk weighted assets)	N/A		N/A		N/A		N/A		N/A		N/A
	Tier 1 capital (to average assets)	395,615		23.3		67,820		4		N/A		N/A
	Blue Hills Bank:
	31-Mar-15
	Total capital (to risk weighted assets)	$	288,836	21.1	%	$	109,751	8	%	$	137,189	10	%
	Tier 1 capital (to risk weighted assets)	274,308		19.9		82,313		6		109,751		8
	Common equity Tier 1(to risk weighted assets)	274,308		19.9		61,735		4.5		89,173		6.5
	Tier 1 capital (to average assets)	274,308		15.9		69,116		4		86,395		5
	31-Dec-14
	Total capital (to risk weighted assets)	$	283,443	22.7	%	$	99,973	8	%	$	124,966	10	%
	Tier 1 capital (to risk weighted assets)	269,513		21.6		49,987		4		74,980		6
	Common equity Tier 1(to risk weighted assets)	N/A		N/A		N/A		N/A		N/A		N/A
	Tier 1 capital (to average assets)	269,513		15.9		67,707		4		84,634		5

Employee_Benefit_Plans

Employee Benefit Plans	3 Months Ended
	Mar. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Employee Benefit Plans	EMPLOYEE STOCK OWNERSHIP PLAN
	The Company maintains an Employee Stock Ownership Plan (“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. 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:
		March 31, 2015
	Allocated	75,912
	Committed to be allocated	18,978
	Unallocated	2,182,455
		2,277,345
	The fair value of unallocated shares was approximately $28.9 million at March 31, 2015.
	Total compensation expense recognized in connection with the ESOP for the three month period ended March 31, 2015 was $248,000. There was no compensation expense recognized in connection with the ESOP during the three months ended March 31, 2014.

Earnings_Per_Common_Share

Earnings Per Common Share	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
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. There were no potentially dilutive common stock equivalents as of March 31, 2015. Earnings (loss) per share is not presented for the period ended March 31, 2014.
		Three Months Ended
		March 31, 2015
		(Dollars in thousands)
	Net income applicable to common stock	$	1,306
	Average number of common shares outstanding	28,466,813
	Less: Average unallocated ESOP shares	(2,192,075		)
	Average number of common shares outstanding used to calculate basic and diluted earnings per common share	26,274,738

Basis_of_Presentation_and_Cons1

Basis of Presentation and Consolidation (Policies)	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Loans Policy	Loan policies
	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 and any deferred fees and costs on originated and 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 or cost recovery method 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 Policy	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. For portfolios for which the Company had no prior loss experience, the national and state peer group losses for relevant portfolios generally over the years 2006-2014 were used. Charge-off factors are updated at least annually and management assesses them quantitatively on a quarterly basis. 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; however, because of the increase in risk exposures new to the Company, it is the intention of management to maintain an allowance that is prudently commensurate with the growth 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 extrapolated historical loss experience for periods ranging from 2006-2014, adjusted for qualitative and environmental factors including levels/trends in delinquencies; trends in volumes and terms of loans; effects of changes in risk selection and underwriting standards and other changes in lending policies, procedures and practices; experience/ability/depth of lending management and staff; and national and local economic trends and conditions.
	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 regional 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 1st or 2nd 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 and real estate collateral. 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 are adversely impacted by a downturn in the economy as evidenced by increased vacancy rates, which in turn, will 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 auto loans. A significant portion of the used auto loan portfolio is comprised of geographically diverse loans originated by and purchased from a third party, who also provides collection services. While this portfolio has generated minimal charge-offs, the provisions for loan losses reflect management’s estimate of inherent losses based on a review of regional and national historical losses of other institutions with similar portfolios.
	Allocated component
	The allocated component relates to loans that are on the watch list (partially charged-off, non-accruing loans and accruing adversely-rated loans) and are 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 greater than or equal to that which would be provided to a borrower with similar credit risk at the time of restructuring.
	Unallocated component
	An unallocated component is maintained to cover uncertainties that could affect management’s estimate of probable losses. The unallocated component of the allowance reflects the margin of imprecision inherent in the underlying assumptions used in the methodologies for estimating allocated and general reserves in the portfolio.

Securities_Available_for_Sale_

Securities Available for Sale (Tables)	3 Months Ended
	Mar. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Available-for-sale Securities	The amortized cost and estimated fair value of securities available for sale, with gross unrealized gains and losses, follows:
		Amortized			Gross		Gross			Fair
		Cost			Unrealized		Unrealized			Value
					Gains		Losses
		(In thousands)
	31-Mar-15
	Debt securities:
	U.S. Treasury	$	598		$	70	$	—		$	668
	Government-sponsored enterprises	26,164			223		—			26,387
	Government-sponsored mortgage-backed and collateralized mortgage obligations	154,342			1,623		(44		)	155,921
	Other mortgage- and asset-backed securities:
	Privately issued commercial mortgage-backed securities	17,532			28		(105		)	17,455
	SBA asset-backed securities	11,565			118		(9		)	11,674
	Other asset-backed securities	10,568			13		(49		)	10,532
	Total other mortgage- and asset-backed securities	39,665			159		(163		)	39,661
	State and political subdivisions	16,258			518		(1		)	16,775
	Financial services:
	Banks	19,446			534		—			19,980
	Diversified financials	23,913			654		(5		)	24,562
	Insurance and REITs	15,932			197		(20		)	16,109
	Total financial services	59,291			1,385		(25		)	60,651
	Other corporate:
	Industrials	48,427			1,025		(36		)	49,416
	Utilities	31,525			580		(69		)	32,036
	Total other corporate	79,952			1,605		(105		)	81,452
	Total debt securities	376,270			5,583		(338		)	381,515
	Marketable equity securities:
	Mutual funds:
	Global equity	5,000			754		—			5,754
	Domestic community	3,216			112		(3		)	3,325
	Global asset allocation	36,956			2,019		(18		)	38,957
	Total marketable equity securities	45,172			2,885		(21		)	48,036
	Total securities available for sale	$	421,442		$	8,468	$	(359	)	$	429,551
		Amortized			Gross		Gross			Fair
		Cost			Unrealized		Unrealized			Value
					Gains		Losses
		(In thousands)
	31-Dec-14
	Debt securities:
	U.S. Treasury	$	13,037		$	182	$	—		$	13,219
	Government-sponsored enterprises	26,335			131		(29		)	26,437
	Government-sponsored mortgage-backed and collateralized mortgage obligations	160,091			756		(294		)	160,553
	Other mortgage- and asset-backed securities:
	Privately issued commercial mortgage-backed securities	22,100			30		(201		)	21,929
	SBA asset-backed securities	27,765			308		(27		)	28,046
	Other asset-backed securities	16,235			—		(43		)	16,192
	Total other mortgage- and asset-backed securities	66,100			338		(271		)	66,167
	State and political subdivisions	15,619			567		(3		)	16,183
	Financial services:
	Banks	12,364			531		(6		)	12,889
	Diversified financials	15,796			354		(18		)	16,132
	Insurance and REITs	9,387			138		(9		)	9,516
	Total financial services	37,547			1,023		(33		)	38,537
	Other corporate:
	Industrials	34,408			681		(54		)	35,035
	Utilities	16,873			265		(120		)	17,018
	Total other corporate	51,281			946		(174		)	52,053
	Total debt securities	370,010			3,943		(804		)	373,149
	Marketable equity securities:
	Mutual funds:
	Global equity	5,000			623		—			5,623
	Domestic community	3,216			86		(5		)	3,297
	Global asset allocation	32,956			1,498		(76		)	34,378
	Total marketable equity securities	41,172			2,207		(81		)	43,298
Total securities available for sale	$	411,182		$	6,150	$	(885	)	$	416,447
Investments Classified by Contractual Maturity Date	The amortized cost and estimated fair value of debt securities by contractual maturity at March 31, 2015 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.
		Amortized			Fair
		Cost			Value
		(In thousands)
	Within 1 year	$	792		$	794
	After 1 year through 5 years	93,391			94,898
	After 5 years through 10 years	77,696			79,338
	After 10 years	10,384			10,903
		182,263			185,933
	Mortgage- and asset-backed securities and collateralized mortgage obligations	194,007			195,582
		$	376,270		$	381,515
Unrealized Gain (Loss) and Fair Value of Investments	Information pertaining to securities available for sale with gross unrealized losses aggregated by investment category and length of time that individual securities have been in a continuous loss position, follows:
		Less Than Twelve Months					More Than Twelve Months
		Gross			Fair		Gross			Fair
		Unrealized			Value		Unrealized			Value
		Losses					Losses
		(In thousands)
	31-Mar-15
	Debt securities:
	Government-sponsored mortgage-backed and collateralized mortgage obligations	$	(37	)	$	12,463	$	(7	)	$	239
	Other mortgage- and asset-backed securities:
	Privately issued commercial mortgage- backed securities	(30		)	6,477		(75		)	7,872
	SBA asset-backed securities	(9		)	5,387		—			—
	Other asset-backed securities	(49		)	5,931		—			—
	Total other mortgage- and asset-backed securities	(88		)	17,795		(75		)	7,872
	State and political subdivisions	(1		)	990		—			—
	Financial services:
	Diversified financials	(5		)	659		—			—
	Insurance and REITs	(20		)	1,051		—			—
	Total financial services	(25		)	1,710		—			—
	Other corporate:
	Industrials	(36		)	4,975		—			—
	Utilities	(69		)	5,273		—			—
	Total other corporate	(105		)	10,248		—			—
	Total debt securities	(256		)	43,206		(82		)	8,111
	Marketable equity securities:
	Mutual funds:
	Domestic community	—			—		(3		)	463
	Global asset allocation	(18		)	3,982		—			—
	Total marketable equity securities	(18		)	3,982		(3		)	463
	Total temporarily impaired securities	$	(274	)	$	47,188	$	(85	)	$	8,574
		Less Than Twelve Months					More Than Twelve Months
		Gross			Fair		Gross			Fair
		Unrealized			Value		Unrealized			Value
		Losses					Losses
		(In thousands)
	31-Dec-14
	Debt securities:
	Government-sponsored enterprises	$	(12	)	$	5,932	$	(17	)	$	1,080
	Government-sponsored mortgage-backed and collateralized mortgage obligations	(190		)	93,364		(104		)	8,425
	Other mortgage- and asset-backed securities:
	Privately issued commercial mortgage- backed securities	(69		)	9,412		(132		)	8,759
	SBA asset-backed securities	(27		)	5,529		—			—
	Other asset-backed securities	(43		)	16,192		—			—
	Total other mortgage- and asset-backed securities	(139		)	31,133		(132		)	8,759
	State and political subdivisions	(3		)	1,955					—
	Financial services:
	Banks	(6		)	2,907		—			—
	Diversified financials	(18		)	7,676		—			—
	Insurance and REITs	(9		)	4,177		—			—
	Total financial services	(33		)	14,760		—			—
	Other corporate:
	Industrials	(54		)	9,575		—			—
	Utilities	(120		)	7,291		—			—
	Total other corporate	(174		)	16,866		—			—
	Total debt securities	(551		)	164,010		(253		)	18,264
	Marketable equity securities:
	Mutual funds:
	Domestic community	—			—		(5		)	462
	Diversified bonds	(76		)	7,057		—			—
	Total marketable equity securities	(76		)	7,057		(5		)	462
	Total temporarily impaired securities	$	(627	)	$	171,067	$	(258	)	$	18,726

Loans_and_The_Allowance_for_Lo1

Loans and The Allowance for Loan Loss (Tables)	3 Months Ended
	Mar. 31, 2015
Receivables [Abstract]
Schedule of Accounts, Notes, Loans and Financing Receivable	A summary of the balances of loans follows:
		March 31,				December 31,
		2015				2014
		(In thousands)
	Real estate:
	1-4 family residential	$	461,903			$	460,273
	Home equity	63,445				61,750
	Commercial real estate	408,003				387,807
	Construction	59,854				53,606
		993,205				963,436
	Commercial business	154,647				151,823
	Consumer	31,999				31,778
	Total loans	1,179,851				1,147,037
	Allowance for loan losses	(13,238		)		(12,973		)
	Discount and fair value adjustments on purchased loans	(3,614		)		(3,850		)
	Deferred loan costs and fees, net	2,768				2,700
	Loans, net	$	1,165,767			$	1,132,914
Activity in Allowance for Loan Losses	Activity in the allowance for loan losses for the three months months ended March 31, 2015 and 2014 and allocation of the allowance to loan segments as of March 31, 2015 and December 31, 2014 follows:
		1-4 Family				Home				Commercial		Construction		Commercial			Consumer			Unallocated			Total
		Residential				Equity				Real Estate				Business
		(In thousands)
	Three Months Ended March 31, 2015
	Allowance at December 31, 2014	$	3,222			$	340			$	3,551	$	1,056	$	3,410		$	736		$	658		$	12,973
	Provision (credit) for loan losses	(7		)		40				171		120		(78		)	25			8			279
	Loans charged-off	—				—				—		—		—			(14		)	—			(14		)
	Recoveries	—				—				—		—		—			—			—			—
	Allowance at March 31, 2015	$	3,215			$	380			$	3,722	$	1,176	$	3,332		$	747		$	666		$	13,238
	Three Months Ended March 31, 2014
	Allowance at December 31, 2013	$	2,835			$	247			$	2,608	$	303	$	2,416		$	574		$	688		$	9,671
	Provision (credit) for loan losses	70				21				320		111		173			49			(30		)	714
	Loans charged-off	(18		)		—				—		—		—			(21		)	—			(39		)
	Recoveries	—				—				—		—		—			—			—			—
	Allowance at March 31, 2014	$	2,887			$	268			$	2,928	$	414	$	2,589		$	602		$	658		$	10,346
Allowance for Credit Losses on Financing Receivables	Additional information pertaining to the allowance for loan losses at March 31, 2015 and December 31, 2014 is as follows:
		1-4 Family				Home				Commercial		Construction		Commercial			Consumer			Unallocated			Total
		Residential				Equity				Real Estate				Business
		(In thousands)
	March 31, 2015
	Allowance related to impaired loans	$	—			$	—			$	—	$	—	$	—		$	—		$	—		$	—
	Allowance related to non-impaired loans	3,215				380				3,722		1,176		3,332			747			666			13,238
	Total allowance for loan losses	$	3,215			$	380			$	3,722	$	1,176	$	3,332		$	747		$	666		$	13,238
	Impaired loans	$	4,694			$	578			$	—	$	—	$	—		$	30		$	—		$	5,302
	Non-impaired loans	457,209				62,867				408,003		59,854		154,647			31,969			—			1,174,549
	Total loans	$	461,903			$	63,445			$	408,003	$	59,854	$	154,647		$	31,999		$	—		$	1,179,851
	December 31, 2014
	Allowance related to impaired loans	$	—			$	—			$	—	$	—	$	—		$	—		$	—		$	—
	Allowance related to non-impaired loans	3,222				340				3,551		1,056		3,410			736			658			12,973
	Total allowance for loan losses	$	3,222			$	340			$	3,551	$	1,056	$	3,410		$	736		$	658		$	12,973
	Impaired loans	$	4,419			$	578			—		$	—	$	—		$	27		$	—		$	5,024
	Non-impaired loans	455,854				61,172				387,807		53,606		151,823			31,751			—			1,142,013
	Total loans	$	460,273			$	61,750			$	387,807	$	53,606	$	151,823		$	31,778		$	—		$	1,147,037
Past Due Financing Receivables	The following is a summary of past due and non-accrual loans, by loan class, at March 31, 2015 and December 31, 2014:
		30-59 Days				60-89 Days				Past Due 90		Total		Loans on
		Past Due				Past Due				Days or More		Past Due		Non-accrual
		(In thousands)
	March 31, 2015
	Real estate:
	1-4 family residential	$	1,131			$	464			$	774	$	2,369	$	4,158
	Home equity	1,967				18				480		2,465		578
	Consumer	518				15				10		543		30
	Total	$	3,616			$	497			$	1,264	$	5,377	$	4,766
	December 31, 2014
	Real estate:
	1-4 family residential	$	3,137			$	522			$	1,370	$	5,029	$	3,876
	Home equity	680				—				475		1,155		578
	Consumer	217				—				5		222		$	27
	Total	$	3,817			$	522			$	1,845	$	6,184	$	4,481
Impaired Financing Receivables	The following is a summary of information pertaining to impaired loans by loan class at the dates indicated:
		Recorded				Unpaid				Related
		Investment				Principal				Allowance
						Balance
	March 31, 2015	(In thousands)
	Impaired loans without a valuation allowance:
	Real estate:
	1-4 family residential	$	4,694			$	5,487			$	—
	Home equity	578				804				—
	Consumer	30				30				—
	Total	$	5,302			$	6,321			$	—
	December 31, 2014
	Impaired loans without a valuation allowance:
	Real estate:
	1-4 family residential	$	4,419			$	5,211			$	—
	Home equity	578				804
	Consumer loans	27				25				—
	Total	$	5,024			$	6,040			$	—
	The following tables set forth information regarding average balances and interest income recognized (all on a cash basis) on impaired loans by class, for the periods indicated:
		Average				Interest
		Recorded				Income
		Investment				Recognized
	Three Months Ended March 31, 2015	(In thousands)
	Real estate:
	1-4 family residential	$	4,557			$	67
	Home equity	578				6
	Consumer	28				—
	Total	$	5,163			$	73
	Three Months Ended March 31, 2014
	Real estate:
	1-4 family residential	$	3,250			$	34
	Home Equity	297				4
	Commercial business	277				4
	Consumer	5				—
	Total	$	3,829			$	42
Troubled Debt Restructurings on Financing Receivables	Troubled debt restructurings entered into during the three months ended March 31, 2015 are as follows:
		Number of contracts			Pre-Modification Outstanding Recorded Investment				Post-Modification Outstanding Recorded Investment
	Real estate:
	1-4 family residential	2			$	469			$	490
Financing Receivable Credit Quality Indicators	The following tables present the Company’s loans by risk rating at March 31, 2015 and December 31, 2014:
		1-4 Family				Home				Commercial		Construction		Commercial			Consumer			Total
		Residential				Equity				Real Estate				Business						Loans
		(In thousands)
	March 31, 2015
	Loans rated 1 - 6	$	3,361			$	471			$	407,394	$	59,854	$	154,503		$	5		$	625,588
	Loans rated 7	3,077				850				609		—		144			—			4,680
	Loans rated 8	1,442				—				—		—		—			30			1,472
	Loans rated 9	709				—				—		—		—			—			709
	Loans rated 10	—				—				—		—		—			—			—
	Loans not rated	453,314				62,124				—		—		—			31,964			547,402
		$	461,903			$	63,445			$	408,003	$	59,854	$	154,647		$	31,999		$	1,179,851
	December 31, 2014
	Loans rated 1 - 6	$	3,381			$	473			$	387,651	$	53,606	$	150,960		$	5		$	596,076
	Loans rated 7	3,095				852				156		—		863			—			4,966
	Loans rated 8	1,331				—				—		—		—			31			1,362
	Loans rated 9	709				—				—		—		—			—			709
	Loans rated 10	—				—				—		—		—			—			—
	Loans not rated	451,757				60,425				—		—		—			31,742			543,924
		$	460,273			$	61,750			$	387,807	$	53,606	$	151,823		$	31,778		$	1,147,037

Interest_Rate_Swap_Agreements_

Interest Rate Swap Agreements (Tables)	3 Months Ended
	Mar. 31, 2015
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 March 31, 2015 and December 31, 2014.
		Derivative Gains				Derivative Losses
		Notional		Fair		Notional		Fair
		Amount		Value		Amount		Value
		(In thousands)
	31-Mar-15
	Economic hedges:
	Commercial loan level interest rate swap agreements	$	197,818	$	7,275	$	197,818	$	7,806
	Other contracts	8,537		11		8,252		103
	Total derivatives	$	206,355	$	7,286	$	206,070	$	7,909
	31-Dec-14
	Economic hedges:
	Commercial loan level interest rate swap agreements	$	202,970	$	5,446	$	202,970	$	5,759
	Other contracts	8,616		8		8,287		83
	Total derivatives	$	211,586	$	5,454	$	211,257	$	5,842

Deposits_Tables

Deposits (Tables)	3 Months Ended
	Mar. 31, 2015
Banking and Thrift [Abstract]
Schedule of Deposit Balances	A summary of deposit balances, by type, is as follows:
		March 31,		December 31,
		2015		2014
		(In thousands)
	NOW and demand	$	256,746	$	245,117
	Regular savings	301,932		303,834
	Money market deposits	269,164		280,139
	Brokered money market	23,991		23,166
	Total non-certificate accounts	851,833		852,256
	Term certificates of $100,000 or more	150,668		142,569
	Term certificates less than $100,000	160,004		159,186
	Brokered certificates of deposit	58,705		58,705
	Total certificate accounts	369,377		360,460
	Total deposits	$	1,221,210	$	1,212,716
Schedule of Contractual Maturities of Deposits and Weighted Average Rate	At March 31, 2015, the scheduled maturities of term certificate accounts, including brokered deposits, are as follows:
		Amount		Weighted
				Average
				Rate
		(Dollars in thousands)
	Within 1 year	$	187,831	0.57	%
	1-2 years	64,608		1.27
	2-3 years	49,097		1.27
	3-4 years	8,995		1.22
	4 years and beyond	58,846		1.99
		$	369,377	1.03	%

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2015
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)
	31-Mar-15
	Assets
	Securities available for sale:
	Debt securities	$	668		$	380,847		$	—	$	381,515
	Marketable equity securities	48,036			—			—		48,036
	Derivative assets	—			7,286			—		7,286
	Total assets	$	48,704		$	388,133		$	—	$	436,837
	Liabilities
	Derivative liabilities	$	—		$	7,909		$	—	$	7,909
	31-Dec-14
	Assets
	Securities available for sale:
	Debt securities	13,219			359,930			—		373,149
	Marketable equity securities	43,298			—			—		43,298
	Derivative assets	—			5,454			—		5,454
	Total assets	$	56,517		$	365,384		$	—	$	421,901
	Liabilities
	Derivative liabilities	$	—		$	5,842		$	—	$	5,842
Fair Value Measurements, Nonrecurring	The following tables summarize losses and fair value hierarchy applicable to assets measured at fair value on a non-recurring basis:
		At December 31, 2014					Three Months Ended March 31, 2014
		Level 1		Level 2	Level 3		Total Losses
		(In thousands)
	Impaired loans	$—		$—	$120		$18
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
		Amount			Level 1			Level 2		Level 3		Total
		(In thousands)
	31-Mar-15
	Financial assets:
	Cash and cash equivalents	$	37,011		$	37,011		$	—	$	—	$	37,011
	Securities available for sale	429,551			48,704			380,847		—		429,551
	Federal Home Loan Bank stock	11,702			—			—		11,702		11,702
	Loans and loans held for sale	1,183,448			—			—		1,168,563		1,168,563
	Accrued interest receivable	4,793			—			—		4,793		4,793
	Financial liabilities:
	Deposits	1,221,210			—			—		1,222,086		1,222,086
	Borrowings	105,000			—			106,155		—		106,155
	On-balance sheet derivative financial instruments:
	Interest rate swap agreements:
	Assets	7,286			—			7,286		—		7,286
	Liabilities	7,909			—			7,909		—		7,909
		Carrying			Fair Value
		Amount			Level 1			Level 2		Level 3		Total
		(In thousands)
	31-Dec-14
	Financial assets:
	Cash and cash equivalents	$	60,146		$	60,146		$	—	$	—	$	60,146
	Securities available for sale	416,447			56,517			359,930		—		416,447
	Federal Home Loan Bank stock	11,702			—			—		11,702		11,702
	Loans and loans held for sale	1,147,505			—			—		1,132,024		1,132,024
	Accrued interest receivable	4,433			—			—		4,433		4,433
	Financial liabilities:
	Deposits	1,212,716			—			—		1,214,251		1,214,251
	Borrowings	75,000			—			76,074		—		76,074
	On-balance sheet derivative financial instruments:
	Interest rate swap agreements:
	Assets	5,454			—			5,454		—		5,454
	Liabilities	5,842			—			5,842		—		5,842

Comprehensive_Income_Tables

Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	Changes in accumulated other comprehensive income, by component, follows:
		Three Months ended March 31, 2015
		Securities Available for Sale			Defined Benefit Pension Plan			Total
	Balance at December 31, 2014	$	3,392		$	(815	)	$	2,577
	Other comprehensive income before reclassification	4,162			—			4,162
	Amounts reclassified	(1,318		)	—			(1,318		)
	Tax effects	(1,060		)	—			(1,060		)
	Net current-period other comprehensive income	1,784			—			1,784
	Balance at March 31, 2015	$	5,176		$	(815	)	$	4,361
		Three Months ended March 31, 2014
		Securities Available for Sale			Defined Benefit Pension Plan			Total
	Balance at December 31, 2013	$	1,983		$	482		$	2,465
	Other comprehensive income before reclassification	4,173			—			4,173
	Amounts reclassified	(541		)	—			(541		)
	Tax effects	(1,398		)	—			(1,398		)
	Net current-period other comprehensive income	2,234			—			2,234
	Balance at March 31, 2014	$	4,217		$	482		$	4,699
	The components of accumulated other comprehensive income, included in stockholders' equity, are as follows:
		March 31,			December 31,
		2015			2014
		(In thousands)
	Securities available for sale:
	Net unrealized gain	$	8,109		$	5,265
	Tax effect	(2,933		)	(1,873		)
	Net-of-tax amount	5,176			3,392
	Defined benefit pension plan:
	Unrecognized net actuarial loss	(1,358		)	(1,358		)
	Tax effect	543			543
	Net-of-tax amount	(815		)	(815		)
		$	4,361		$	2,577

Stockholders_Equity_Tables

Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations	The Bank’s and the Company’s actual and minimum required capital amounts and ratios as of March 31, 2015 and December 31, 2014 are presented below.
		Actual				Minimum				Minimum
						Capital				To Be Well
						Requirement				Capitalized
		Amount		Ratio		Amount		Ratio		Amount		Ratio
		(Dollars in thousands)
	Blue Hills Bancorp, Inc.:
	31-Mar-15
	Total capital (to risk weighted assets)	$	414,618	30.2	%	$	109,983	8	%	137,749		10	%
	Tier 1 capital (to risk weighted assets)	400,090		29.1		82,487		6		109,983		8
	Common equity Tier 1(to risk weighted assets)	400,090		29.1		61,866		4.5		89,361		6.5
	Tier 1 capital (to average assets)	400,090		23.1		69,229		4		86,535		5
	31-Dec-14
	Total capital (to risk weighted assets)	$	409,545	32.6	%	$	100,513	8	%	N/A		N/A
	Tier 1 capital (to risk weighted assets)	395,615		31.5		50,527		4		N/A		N/A
	Common equity Tier 1(to risk weighted assets)	N/A		N/A		N/A		N/A		N/A		N/A
	Tier 1 capital (to average assets)	395,615		23.3		67,820		4		N/A		N/A
	Blue Hills Bank:
	31-Mar-15
	Total capital (to risk weighted assets)	$	288,836	21.1	%	$	109,751	8	%	$	137,189	10	%
	Tier 1 capital (to risk weighted assets)	274,308		19.9		82,313		6		109,751		8
	Common equity Tier 1(to risk weighted assets)	274,308		19.9		61,735		4.5		89,173		6.5
	Tier 1 capital (to average assets)	274,308		15.9		69,116		4		86,395		5
	31-Dec-14
	Total capital (to risk weighted assets)	$	283,443	22.7	%	$	99,973	8	%	$	124,966	10	%
	Tier 1 capital (to risk weighted assets)	269,513		21.6		49,987		4		74,980		6
	Common equity Tier 1(to risk weighted assets)	N/A		N/A		N/A		N/A		N/A		N/A
	Tier 1 capital (to average assets)	269,513		15.9		67,707		4		84,634		5

Employee_Benefit_Plans_Tables

Employee Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Employee Stock Ownership Plan (ESOP) Disclosures	Shares held by the ESOP include the following:
		March 31, 2015
	Allocated	75,912
	Committed to be allocated	18,978
	Unallocated	2,182,455
		2,277,345

Earnings_Per_Common_Share_Tabl

Earnings Per Common Share (Tables)	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted
		Three Months Ended
		March 31, 2015
		(Dollars in thousands)
	Net income applicable to common stock	$	1,306
	Average number of common shares outstanding	28,466,813
	Less: Average unallocated ESOP shares	(2,192,075		)
	Average number of common shares outstanding used to calculate basic and diluted earnings per common share	26,274,738

Basis_of_Presentation_and_Cons2

Basis of Presentation and Consolidation (Details) (USD $)	0 Months Ended	1 Months Ended	3 Months Ended
	Jul. 21, 2014	Jul. 31, 2014	Mar. 31, 2015
Subsidiary or Equity Method Investee [Line Items]
New shares issued during period (shares)	27,772,500
Shares issued (in dollars per share)	$10
Net proceeds from issuance of common stock	$277,725,000
Employee stock ownership plan, shares	2,277,345
Employee stock ownership plan, value	22,773,450
Blue Hills Bank Foundation
Subsidiary or Equity Method Investee [Line Items]
New shares issued during period (shares)	694,313
Capital contribution to affiliate	7,000,000
Cash payment to affiliate		$57,000
1-4 Family Residential
Subsidiary or Equity Method Investee [Line Items]
Origination covenants, maximum loan-to-value ratio			80.00%

Securities_Available_for_Sale_1

Securities Available for Sale - Available-for-sale Securities (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Debt securities:
Amortized Cost	$376,270	$370,010
Gross Unrealized Gains	5,583	3,943
Gross Unrealized Losses	-338	-804
Fair Value	381,515	373,149
Marketable equity securities:
Amortized Cost	45,172	41,172
Gross Unrealized Gains	2,885	2,207
Gross Unrealized Losses	-21	-81
Fair Value	48,036	43,298
Available-for-sale securities:
Amortized Cost	421,442	411,182
Gross Unrealized Gains	8,468	6,150
Gross Unrealized Losses	-359	-885
Fair Value	429,551	416,447
U.S. Treasury
Debt securities:
Amortized Cost	598	13,037
Gross Unrealized Gains	70	182
Gross Unrealized Losses	0	0
Fair Value	668	13,219
Government-sponsored enterprises
Debt securities:
Amortized Cost	26,164	26,335
Gross Unrealized Gains	223	131
Gross Unrealized Losses	0	-29
Fair Value	26,387	26,437
Government-sponsored mortgage-backed and collateralized mortgage obligations
Debt securities:
Amortized Cost	154,342	160,091
Gross Unrealized Gains	1,623	756
Gross Unrealized Losses	-44	-294
Fair Value	155,921	160,553
Privately issued commercial mortgage- backed securities
Debt securities:
Amortized Cost	17,532	22,100
Gross Unrealized Gains	28	30
Gross Unrealized Losses	-105	-201
Fair Value	17,455	21,929
SBA asset-backed securities
Debt securities:
Amortized Cost	11,565	27,765
Gross Unrealized Gains	118	308
Gross Unrealized Losses	-9	-27
Fair Value	11,674	28,046
Other asset-backed securities
Debt securities:
Amortized Cost	10,568	16,235
Gross Unrealized Gains	13	0
Gross Unrealized Losses	-49	-43
Fair Value	10,532	16,192
Total other mortgage- and asset-backed securities
Debt securities:
Amortized Cost	39,665	66,100
Gross Unrealized Gains	159	338
Gross Unrealized Losses	-163	-271
Fair Value	39,661	66,167
State and political
Debt securities:
Amortized Cost	16,258	15,619
Gross Unrealized Gains	518	567
Gross Unrealized Losses	-1	-3
Fair Value	16,775	16,183
Global Equity
Marketable equity securities:
Amortized Cost	5,000	5,000
Gross Unrealized Gains	754	623
Gross Unrealized Losses	0	0
Fair Value	5,754	5,623
Domestic community
Marketable equity securities:
Amortized Cost	3,216	3,216
Gross Unrealized Gains	112	86
Gross Unrealized Losses	-3	-5
Fair Value	3,325	3,297
Global asset allocation
Marketable equity securities:
Amortized Cost	36,956	32,956
Gross Unrealized Gains	2,019	1,498
Gross Unrealized Losses	-18	-76
Fair Value	38,957	34,378
Financial Services | Corporate debt securities
Debt securities:
Amortized Cost	59,291	37,547
Gross Unrealized Gains	1,385	1,023
Gross Unrealized Losses	-25	-33
Fair Value	60,651	38,537
Banks | Corporate debt securities
Debt securities:
Amortized Cost	19,446	12,364
Gross Unrealized Gains	534	531
Gross Unrealized Losses	0	-6
Fair Value	19,980	12,889
Diversified Financials | Corporate debt securities
Debt securities:
Amortized Cost	23,913	15,796
Gross Unrealized Gains	654	354
Gross Unrealized Losses	-5	-18
Fair Value	24,562	16,132
Insurance and REITs | Corporate debt securities
Debt securities:
Amortized Cost	15,932	9,387
Gross Unrealized Gains	197	138
Gross Unrealized Losses	-20	-9
Fair Value	16,109	9,516
Other Corporate | Corporate debt securities
Debt securities:
Amortized Cost	79,952	51,281
Gross Unrealized Gains	1,605	946
Gross Unrealized Losses	-105	-174
Fair Value	81,452	52,053
Industrials | Corporate debt securities
Debt securities:
Amortized Cost	48,427	34,408
Gross Unrealized Gains	1,025	681
Gross Unrealized Losses	-36	-54
Fair Value	49,416	35,035
Utilities | Corporate debt securities
Debt securities:
Amortized Cost	31,525	16,873
Gross Unrealized Gains	580	265
Gross Unrealized Losses	-69	-120
Fair Value	$32,036	$17,018

Securities_Available_for_Sale_2

Securities Available for Sale - Schedule of Contractual Maturities of Securities (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Within 1 year	$792
After 1 year through 5 years	93,391
After 5 years through 10 years	77,696
After 10 years	10,384
Single Maturity Date, amortized cost basis	182,263
Mortgage- and asset-backed securities and collateralized mortgage obligations - Amortized Basis	194,007
Amortized Cost	376,270	370,010
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Within 1 year	794
After 1 year through 5 years	94,898
After 5 years through 10 years	79,338
After 10 years	10,903
Single Maturity Date	185,933
Mortgage- and asset-backed securities and collateralized mortgage obligations - Fair Value	195,582
Available-for-sale securities, total debt securities	$381,515	$373,149

Securities_Available_for_Sale_3

Securities Available for Sale - Available-for-sale Securities Unrealized Loss (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months	($274)	($627)
Gross Unrealized Losses - More than twelve months	-85	-258
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months	47,188	171,067
Fair Value - More than twelve months	8,574	18,726
Total debt securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months	-256	-551
Gross Unrealized Losses - More than twelve months	-82	-253
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months	43,206	164,010
Fair Value - More than twelve months	8,111	18,264
Government-sponsored enterprises
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months		-12
Gross Unrealized Losses - More than twelve months		-17
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months		5,932
Fair Value - More than twelve months		1,080
Government-sponsored mortgage-backed and collateralized mortgage obligations
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months	-37	-190
Gross Unrealized Losses - More than twelve months	-7	-104
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months	12,463	93,364
Fair Value - More than twelve months	239	8,425
Privately issued commercial mortgage- backed securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months	-30	-69
Gross Unrealized Losses - More than twelve months	-75	-132
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months	6,477	9,412
Fair Value - More than twelve months	7,872	8,759
SBA asset-backed securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months	-9	-27
Gross Unrealized Losses - More than twelve months	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months	5,387	5,529
Fair Value - More than twelve months	0	0
Other asset-backed securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months	-49	-43
Gross Unrealized Losses - More than twelve months	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months	5,931	16,192
Fair Value - More than twelve months	0	0
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	-88	-139
Gross Unrealized Losses - More than twelve months	-75	-132
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months	17,795	31,133
Fair Value - More than twelve months	7,872	8,759
State and political
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months	-1	-3
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	990	1,955
Fair Value - More than twelve months	0	0
Total marketable equity securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months	-18	-76
Gross Unrealized Losses - More than twelve months	-3	-5
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months	3,982	7,057
Fair Value - More than twelve months	463	462
Domestic community
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months	0	0
Gross Unrealized Losses - More than twelve months	-3	-5
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months	0	0
Fair Value - More than twelve months	463	462
Diversified bonds
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months		-76
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		7,057
Fair Value - More than twelve months		0
Global asset allocation
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months	-18
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	3,982
Fair Value - More than twelve months	0
Financial Services | Corporate debt securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months	-25	-33
Gross Unrealized Losses - More than twelve months	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months	1,710	14,760
Fair Value - More than twelve months	0	0
Banks | Corporate debt securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months		-6
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		2,907
Fair Value - More than twelve months		0
Diversified Financials | Corporate debt securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months	-5	-18
Gross Unrealized Losses - More than twelve months	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months	659	7,676
Fair Value - More than twelve months	0	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	-20	-9
Gross Unrealized Losses - More than twelve months	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months	1,051	4,177
Fair Value - More than twelve months	0	0
Other Corporate | Corporate debt securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months	-105	-174
Gross Unrealized Losses - More than twelve months	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months	10,248	16,866
Fair Value - More than twelve months	0	0
Industrials | Corporate debt securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months	-36	-54
Gross Unrealized Losses - More than twelve months	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months	4,975	9,575
Fair Value - More than twelve months	0	0
Utilities | Corporate debt securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Gross Unrealized Losses - Less than twelve months	-69	-120
Gross Unrealized Losses - More than twelve months	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Fair Value - Less than twelve months	5,273	7,291
Fair Value - More than twelve months	$0	$0

Securities_Available_for_Sale_4

Securities Available for Sale - Narrative (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]
Depreciation, percentage of amortized cost basis	1.00%
Gross Unrealized Losses - More than twelve months	$85	$258
Mutual Funds
Schedule of Available-for-sale Securities [Line Items]
Depreciation, percentage of amortized cost basis	1.00%
Unrealized loss position, number of positions, more than twelve months	2
Gross Unrealized Losses - More than twelve months	$21

Loans_and_The_Allowance_for_Lo2

Loans and The Allowance for Loan Loss - Summary of Loan balances (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$1,179,851	$1,147,037
Allowance for loan losses	-13,238	-12,973
Discount and fair value adjustments on purchased loans	-3,614	-3,850
Deferred loan costs and fees, net	2,768	2,700
Loans, net	1,165,767	1,132,914
Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	993,205	963,436
1-4 Family Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	461,903	460,273
Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	63,445	61,750
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	408,003	387,807
Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	59,854	53,606
Commercial Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	154,647	151,823
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$31,999	$31,778

Loans_and_The_Allowance_for_Lo3

Loans and The Allowance for Loan Loss - Activity in Allowance for Loan Losses (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Beginning Allowance	$12,973	$9,671
Provision (credit) for loan losses	279	714
Loans charged-off	-14	-39
Recoveries	0	0
Loans and Leases Receivable, Ending Allowance	13,238	10,346
1-4 Family Residential
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Beginning Allowance	3,222	2,835
Provision (credit) for loan losses	-7	70
Loans charged-off	0	-18
Recoveries	0	0
Loans and Leases Receivable, Ending Allowance	3,215	2,887
Home Equity
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Beginning Allowance	340	247
Provision (credit) for loan losses	40	21
Loans charged-off	0	0
Recoveries	0	0
Loans and Leases Receivable, Ending Allowance	380	268
Commercial Real Estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Beginning Allowance	3,551	2,608
Provision (credit) for loan losses	171	320
Loans charged-off	0	0
Recoveries	0	0
Loans and Leases Receivable, Ending Allowance	3,722	2,928
Construction
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Beginning Allowance	1,056	303
Provision (credit) for loan losses	120	111
Loans charged-off	0	0
Recoveries	0	0
Loans and Leases Receivable, Ending Allowance	1,176	414
Commercial Business
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Beginning Allowance	3,410	2,416
Provision (credit) for loan losses	-78	173
Loans charged-off	0	0
Recoveries	0	0
Loans and Leases Receivable, Ending Allowance	3,332	2,589
Consumer
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Beginning Allowance	736	574
Provision (credit) for loan losses	25	49
Loans charged-off	-14	-21
Recoveries	0	0
Loans and Leases Receivable, Ending Allowance	747	602
Unallocated
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Beginning Allowance	658	688
Provision (credit) for loan losses	8	-30
Loans charged-off	0	0
Recoveries	0	0
Loans and Leases Receivable, Ending Allowance	$666	$658

Loans_and_The_Allowance_for_Lo4

Loans and The Allowance for Loan Loss - Additional Activity in Allowance for Loan Losses (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance related to impaired loans	$0	$0
Allowance related to non-impaired loans	13,238	12,973
Total allowance for loan losses	13,238	12,973	10,346	9,671
Impaired loans	5,302	5,024
Non-impaired loans	1,174,549	1,142,013
Total loans	1,179,851	1,147,037
1-4 Family Residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance related to impaired loans	0	0
Allowance related to non-impaired loans	3,215	3,222
Total allowance for loan losses	3,215	3,222	2,887	2,835
Impaired loans	4,694	4,419
Non-impaired loans	457,209	455,854
Total loans	461,903	460,273
Home Equity
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance related to impaired loans	0	0
Allowance related to non-impaired loans	380	340
Total allowance for loan losses	380	340	268	247
Impaired loans	578	578
Non-impaired loans	62,867	61,172
Total loans	63,445	61,750
Commercial Real Estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance related to impaired loans	0	0
Allowance related to non-impaired loans	3,722	3,551
Total allowance for loan losses	3,722	3,551	2,928	2,608
Impaired loans	0	0
Non-impaired loans	408,003	387,807
Total loans	408,003	387,807
Construction
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance related to impaired loans	0	0
Allowance related to non-impaired loans	1,176	1,056
Total allowance for loan losses	1,176	1,056	414	303
Impaired loans	0	0
Non-impaired loans	59,854	53,606
Total loans	59,854	53,606
Commercial Business
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance related to impaired loans	0	0
Allowance related to non-impaired loans	3,332	3,410
Total allowance for loan losses	3,332	3,410	2,589	2,416
Impaired loans	0	0
Non-impaired loans	154,647	151,823
Total loans	154,647	151,823
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance related to impaired loans	0	0
Allowance related to non-impaired loans	747	736
Total allowance for loan losses	747	736	602	574
Impaired loans	30	27
Non-impaired loans	31,969	31,751
Total loans	31,999	31,778
Unallocated
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance related to impaired loans	0	0
Allowance related to non-impaired loans	666	658
Total allowance for loan losses	666	658	658	688
Impaired loans	0	0
Non-impaired loans	0	0
Total loans	$0	$0

Loans_and_The_Allowance_for_Lo5

Loans and The Allowance for Loan Loss - Summary of Past Due and Non-accrual loans, by class (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	$3,616	$3,817
60-89 Days Past Due	497	522
Past Due 90 Days or More	1,264	1,845
Total Past Due	5,377	6,184
Loans on Non-accrual	4,766	4,481
1-4 Family Residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	1,131	3,137
60-89 Days Past Due	464	522
Past Due 90 Days or More	774	1,370
Total Past Due	2,369	5,029
Loans on Non-accrual	4,158	3,876
Home Equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	1,967	680
60-89 Days Past Due	18	0
Past Due 90 Days or More	480	475
Total Past Due	2,465	1,155
Loans on Non-accrual	578	578
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	518	217
60-89 Days Past Due	15	0
Past Due 90 Days or More	10	5
Total Past Due	543	222
Loans on Non-accrual	$30	$27

Loans_and_The_Allowance_for_Lo6

Loans and The Allowance for Loan Loss - Summary of Impaired Loans (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Financing Receivable, Impaired [Line Items]
Recorded Investment	$5,302	$5,024
Unpaid Principal Balance	6,321	6,040
Related Allowance	0	0
1-4 Family Residential
Financing Receivable, Impaired [Line Items]
Recorded Investment	4,694	4,419
Unpaid Principal Balance	5,487	5,211
Related Allowance	0	0
Home Equity
Financing Receivable, Impaired [Line Items]
Recorded Investment	578	578
Unpaid Principal Balance	804	804
Related Allowance	0
Consumer
Financing Receivable, Impaired [Line Items]
Recorded Investment	30	27
Unpaid Principal Balance	30	25
Related Allowance	$0	$0

Loans_and_The_Allowance_for_Lo7

Loans and The Allowance for Loan Loss - Summary of Average Recorded Investments and Interest Income of Impaired Loans (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	$5,163	$3,829
Interest Income Recognized	73	42
1-4 Family Residential
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	4,557	3,250
Interest Income Recognized	67	34
Home Equity
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	578	297
Interest Income Recognized	6	4
Commercial Business
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		277
Interest Income Recognized		4
Consumer
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	28	5
Interest Income Recognized	$0	$0

Loans_and_The_Allowance_for_Lo8

Loans and The Allowance for Loan Loss - Troubled Debt Restructurings (Details) (1-4 Family Residential, USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015
	contract
1-4 Family Residential
Financing Receivable, Modifications [Line Items]
Number of contracts	2
Pre-Modification Outstanding Recorded Investment	$469
Post-Modification Outstanding Recorded Investment	$490

Loans_and_The_Allowance_for_Lo9

Loans and The Allowance for Loan Loss - Summary of Loan by Risk Rating (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Financing Receivable, Recorded Investment [Line Items]
Total loans	$1,179,851	$1,147,037
1-4 Family Residential
Financing Receivable, Recorded Investment [Line Items]
Total loans	461,903	460,273
Home Equity
Financing Receivable, Recorded Investment [Line Items]
Total loans	63,445	61,750
Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	408,003	387,807
Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans	59,854	53,606
Commercial Business
Financing Receivable, Recorded Investment [Line Items]
Total loans	154,647	151,823
Consumer
Financing Receivable, Recorded Investment [Line Items]
Total loans	31,999	31,778
Loans rated 1 - 6
Financing Receivable, Recorded Investment [Line Items]
Total loans	625,588	596,076
Loans rated 1 - 6 | 1-4 Family Residential
Financing Receivable, Recorded Investment [Line Items]
Total loans	3,361	3,381
Loans rated 1 - 6 | Home Equity
Financing Receivable, Recorded Investment [Line Items]
Total loans	471	473
Loans rated 1 - 6 | Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	407,394	387,651
Loans rated 1 - 6 | Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans	59,854	53,606
Loans rated 1 - 6 | Commercial Business
Financing Receivable, Recorded Investment [Line Items]
Total loans	154,503	150,960
Loans rated 1 - 6 | Consumer
Financing Receivable, Recorded Investment [Line Items]
Total loans	5	5
Loans rated 7
Financing Receivable, Recorded Investment [Line Items]
Total loans	4,680	4,966
Loans rated 7 | 1-4 Family Residential
Financing Receivable, Recorded Investment [Line Items]
Total loans	3,077	3,095
Loans rated 7 | Home Equity
Financing Receivable, Recorded Investment [Line Items]
Total loans	850	852
Loans rated 7 | Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	609	156
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	144	863
Loans rated 7 | Consumer
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loans rated 8
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,472	1,362
Loans rated 8 | 1-4 Family Residential
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,442	1,331
Loans rated 8 | Home Equity
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loans rated 8 | Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
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	0
Loans rated 8 | Consumer
Financing Receivable, Recorded Investment [Line Items]
Total loans	30	31
Loans rated 9
Financing Receivable, Recorded Investment [Line Items]
Total loans	709	709
Loans rated 9 | 1-4 Family Residential
Financing Receivable, Recorded Investment [Line Items]
Total loans	709	709
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	547,402	543,924
Loans not rated | 1-4 Family Residential
Financing Receivable, Recorded Investment [Line Items]
Total loans	453,314	451,757
Loans not rated | Home Equity
Financing Receivable, Recorded Investment [Line Items]
Total loans	62,124	60,425
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	$31,964	$31,742

Interest_Rate_Swap_Agreements_1

Interest Rate Swap Agreements (Details) (Not Designated as Hedging Instrument, USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Derivatives, Fair Value [Line Items]
Derivative Gains, notional amount	$206,355	$211,586
Derivative Gains, fair value	7,286	5,454
Derivative Losses, notional amount	206,070	211,257
Derivative Losses, fair value	7,909	5,842
Interest Rate Swap
Derivatives, Fair Value [Line Items]
Derivative Gains, notional amount	197,818	202,970
Derivative Gains, fair value	7,275	5,446
Derivative Losses, notional amount	197,818	202,970
Derivative Losses, fair value	7,806	5,759
Other Contract
Derivatives, Fair Value [Line Items]
Derivative Gains, notional amount	8,537	8,616
Derivative Gains, fair value	11	8
Derivative Losses, notional amount	8,252	8,287
Derivative Losses, fair value	$103	$83

Deposits_Summary_of_Deposit_Ba

Deposits - Summary of Deposit Balances (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Banking and Thrift [Abstract]
NOW and demand	$256,746	$245,117
Regular savings	301,932	303,834
Money market deposits	269,164	280,139
Brokered money market	23,991	23,166
Total non-certificate accounts	851,833	852,256
Term certificates of $100,000 or more	150,668	142,569
Term certificates less than $100,000	160,004	159,186
Brokered certificates of deposit	58,705	58,705
Total certificate accounts	369,377	360,460
Total deposits	$1,221,210	$1,212,716

Deposits_Schedule_of_Contractu

Deposits - Schedule of Contractual Maturities (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Time Deposits, Fiscal Year Maturity [Abstract]
Amount - Within 1 year	$187,831
Amount - 1-2 years	64,608
Amount - 2-3 years	49,097
Amount - 3-4 years	8,995
Amount - 4 years and beyond	58,846
Total certificate accounts	$369,377	$360,460
Weighted Average Rate of Time Deposits [Abstract]
Weighted Average Rate - Within 1 year	0.57%
Weighted Average Rate - 1-2 years	1.27%
Weighted Average Rate - 2-3 years	1.27%
Weighted Average Rate - 3-4 years	1.22%
Weighted Average Rate - 4 years and beyond	1.99%
Weighted Average Rate	1.03%

Fair_Value_Measurements_Assets

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Assets
Debt securities	$381,515	$373,149
Marketable equity securities	48,036	43,298
Recurring
Assets
Debt securities	381,515	373,149
Marketable equity securities	48,036	43,298
Derivative assets	7,286	5,454
Total assets	436,837	421,901
Liabilities
Derivative liabilities	7,909	5,842
Recurring | Level 1
Assets
Debt securities	668	13,219
Marketable equity securities	48,036	43,298
Derivative assets	0	0
Total assets	48,704	56,517
Liabilities
Derivative liabilities	0	0
Recurring | Level 2
Assets
Debt securities	380,847	359,930
Marketable equity securities	0	0
Derivative assets	7,286	5,454
Total assets	388,133	365,384
Liabilities
Derivative liabilities	7,909	5,842
Recurring | Level 3
Assets
Debt securities	0	0
Marketable equity securities	0	0
Derivative assets	0	0
Total assets	0	0
Liabilities
Derivative liabilities	$0	$0

Fair_Value_Measurements_Assets1

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Losses	$18
Nonrecurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0
Nonrecurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0
Nonrecurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	$120

Fair_Value_Measurements_Summar

Fair Value Measurements - Summary of Fair Value, Balance Sheet Grouping (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Financial assets:
Securities available for sale	$429,551	$416,447
Estimate of Fair Value Measurement
Financial assets:
Cash and cash equivalents	37,011	60,146
Securities available for sale	429,551	416,447
Federal Home Loan Bank stock	11,702	11,702
Loans and loans held for sale	1,168,563	1,132,024
Accrued interest receivable	4,793	4,433
Financial liabilities:
Deposits	1,222,086	1,214,251
Borrowings	106,155	76,074
Carrying Amount
Financial assets:
Cash and cash equivalents	37,011	60,146
Securities available for sale	429,551	416,447
Federal Home Loan Bank stock	11,702	11,702
Loans and loans held for sale	1,183,448	1,147,505
Accrued interest receivable	4,793	4,433
Financial liabilities:
Deposits	1,221,210	1,212,716
Borrowings	105,000	75,000
Level 1
Financial assets:
Cash and cash equivalents	37,011	60,146
Securities available for sale	48,704	56,517
Federal Home Loan Bank stock	0	0
Loans and loans held for sale	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	380,847	359,930
Federal Home Loan Bank stock	0	0
Loans and loans held for sale	0	0
Accrued interest receivable	0	0
Financial liabilities:
Deposits	0	0
Borrowings	106,155	76,074
Level 3
Financial assets:
Cash and cash equivalents	0	0
Securities available for sale	0	0
Federal Home Loan Bank stock	11,702	11,702
Loans and loans held for sale	1,168,563	1,132,024
Accrued interest receivable	4,793	4,433
Financial liabilities:
Deposits	1,222,086	1,214,251
Borrowings	0	0
Interest Rate Swap | Estimate of Fair Value Measurement
Financial liabilities:
Derivative assets	7,286	5,454
Derivative liabilities	7,909	5,842
Interest Rate Swap | Carrying Amount
Financial liabilities:
Derivative assets	7,286	5,454
Derivative liabilities	7,909	5,842
Interest Rate Swap | Level 1
Financial liabilities:
Derivative assets	0	0
Derivative liabilities	0	0
Interest Rate Swap | Level 2
Financial liabilities:
Derivative assets	7,286	5,454
Derivative liabilities	7,909	5,842
Interest Rate Swap | Level 3
Financial liabilities:
Derivative assets	0	0
Derivative liabilities	$0	$0

Comprehensive_Income_Changes_i

Comprehensive Income - Changes in Accumulated Other Comprehensive Income (Loss) by Component (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	$2,577	$2,465
Other comprehensive income before reclassification	4,162	4,173
Amounts reclassified	-1,318	-541
Tax effects	-1,060	-1,398
Other comprehensive income	1,784	2,234
Ending Balance	4,361	4,699
Securities Available for Sale
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	3,392	1,983
Other comprehensive income before reclassification	4,162	4,173
Amounts reclassified	-1,318	-541
Tax effects	-1,060	-1,398
Other comprehensive income	1,784	2,234
Ending Balance	5,176	4,217
Defined Benefit Pension Plan
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	-815	482
Other comprehensive income before reclassification	0	0
Amounts reclassified	0	0
Tax effects	0	0
Other comprehensive income	0	0
Ending Balance	($815)	$482

Comprehensive_Income_Component

Comprehensive Income - Components of Accumulated Other Comprehensive Income (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income	$4,361	$2,577	$4,699	$2,465
Securities Available for Sale
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), before Tax	8,109	5,265
Tax effect	-2,933	-1,873
Accumulated other comprehensive income	5,176	3,392	4,217	1,983
Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), before Tax	-1,358	-1,358
Tax effect	543	543
Accumulated other comprehensive income	($815)	($815)

Stockholders_Equity_Details

Stockholders' Equity (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Jul. 31, 2013	Jul. 30, 2013
In Thousands, unless otherwise specified
Capital [Abstract]
Actual - Total Capital	$414,618	$409,545
Actual - Total Capital to Risk Weighted Assets Ratio (percentage)	30.20%	32.60%
Minimum Capital Requirement - Total Capital	109,983	100,513
Minimum Capital Requirement - Total Capital to Risk Weighted Assets (percentage)	8.00%	8.00%
Minimum to Be Well Capitalized - Total Capital	137,749
Minimum to Be Well Capitalized - Total Capital to Risk Weighted Assets Ratio (percentage)	10.00%
Tier One Risk Based Capital [Abstract]
Actual - Tier 1 Capital to Risk Weighted Assets	400,090	395,615
Actual - Tier 1 Capital to Risk Weighted Assets Ratio (percentage)	29.10%	31.50%
Minimum Capital Requirement - Tier 1 Capital to Risk Weighted Assets	82,487	50,527
Minimum Capital Requirement - Tier 1 Capital to Risk Weighted Assets Ratio (percentage)	6.00%	4.00%	6.00%	4.00%
Minimum to Be Well Capitalized - Tier 1 Capital to Risk Weighted Assets	109,983
Minimum to Be Well Capitalized - Tier 1 Capital to Risk Weighted Assets Ratio (percentage)	8.00%
Common Equity Risk Based Capital [Abstract]
Actual - Common Equity to Risk Weighted Assets	400,090
Actual - Common Equity to Risk Weighted Assets (percentage)	29.10%
Minimum Capital Requirement - Common Equity to Risk Weighted Assets	61,866
Minimum Capital Requirement - Common Equity to Risk Weighted Assets (percentage)	4.50%
Minimum to Be Well Capitalized - Common Equity to Risk Weighted Assets	89,361
Minimum to Be Well Capitalized - Common Equity to Risk Weighted Assets (percentage)	6.50%
Tier One Leverage Capital [Abstract]
Actual - Tier 1 Capital to Average Assets	400,090	395,615
Actual - Tier 1 Capital to Average Assets Ratio (percentage)	23.10%	23.30%
Minimum Capital Requirement - Tier 1 Capital to Average Assets	69,229	67,820
Minimum Capital Requirement - Tier 1 Capital to Average Assets Ratio (percentage)	4.00%	4.00%	4.00%
Minimum to Be Well Capitalized - Tier 1 Capital to Average Assets	86,535
Minimum to Be Well Capitalized - Tier 1 Capital to Average Assets Ratio (percentage)	5.00%
Blue Hills Bank
Capital [Abstract]
Actual - Total Capital	288,836	283,443
Actual - Total Capital to Risk Weighted Assets Ratio (percentage)	21.10%	22.70%
Minimum Capital Requirement - Total Capital	109,751	99,973
Minimum Capital Requirement - Total Capital to Risk Weighted Assets (percentage)	8.00%	8.00%
Minimum to Be Well Capitalized - Total Capital	137,189	124,966
Minimum to Be Well Capitalized - Total Capital to Risk Weighted Assets Ratio (percentage)	10.00%	10.00%
Tier One Risk Based Capital [Abstract]
Actual - Tier 1 Capital to Risk Weighted Assets	274,308	269,513
Actual - Tier 1 Capital to Risk Weighted Assets Ratio (percentage)	19.90%	21.60%
Minimum Capital Requirement - Tier 1 Capital to Risk Weighted Assets	82,313	49,987
Minimum Capital Requirement - Tier 1 Capital to Risk Weighted Assets Ratio (percentage)	6.00%	4.00%
Minimum to Be Well Capitalized - Tier 1 Capital to Risk Weighted Assets	109,751	74,980
Minimum to Be Well Capitalized - Tier 1 Capital to Risk Weighted Assets Ratio (percentage)	8.00%	6.00%
Common Equity Risk Based Capital [Abstract]
Actual - Common Equity to Risk Weighted Assets	274,308
Actual - Common Equity to Risk Weighted Assets (percentage)	19.90%
Minimum Capital Requirement - Common Equity to Risk Weighted Assets	61,735
Minimum Capital Requirement - Common Equity to Risk Weighted Assets (percentage)	4.50%
Minimum to Be Well Capitalized - Common Equity to Risk Weighted Assets	89,173
Minimum to Be Well Capitalized - Common Equity to Risk Weighted Assets (percentage)	6.50%
Tier One Leverage Capital [Abstract]
Actual - Tier 1 Capital to Average Assets	274,308	269,513
Actual - Tier 1 Capital to Average Assets Ratio (percentage)	15.90%	15.90%
Minimum Capital Requirement - Tier 1 Capital to Average Assets	69,116	67,707
Minimum Capital Requirement - Tier 1 Capital to Average Assets Ratio (percentage)	4.00%	4.00%
Minimum to Be Well Capitalized - Tier 1 Capital to Average Assets	$86,395	$84,634
Minimum to Be Well Capitalized - Tier 1 Capital to Average Assets Ratio (percentage)	5.00%	5.00%

Stockholders_Equity_Additional

Stockholders' Equity -Additional Information (Details)	Mar. 31, 2015	Dec. 31, 2014	Jul. 31, 2013	Jul. 30, 2013
Equity [Abstract]
Tier one common capital to risk weighted assets			4.50%
Tier one risk based capital required for capital adequacy to risk weighted assets	6.00%	4.00%	6.00%	4.00%
Tier one leverage capital required for capital adequacy to average assets	4.00%	4.00%	4.00%
Tier one capital conservation buffer common equity capital to risk weighted assets			2.50%

Employee_Benefit_Plans_Employe

Employee Benefit Plans Employee Stock Ownership Plan (Details)	Mar. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Allocated	75,912
Committed to be allocated	18,978
Unallocated	2,182,455
Total	2,277,345

Employee_Benefit_Plans_Additio

Employee Benefit Plans Additional information (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Compensation and Retirement Disclosure [Abstract]
ESOP, Number of shares committed to be released annually	75,912
Fair Value of unallocated shares	$28,900,000
ESOP expense	$248,000	$0

Earnings_Per_Common_Share_Deta

Earnings Per Common Share (Details) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Earnings Per Share [Abstract]
Net income applicable to common stock	$1,306	($399)
Average number of common shares outstanding	28,466,813
Less: Average unallocated ESOP shares	-2,192,075
Average number of common shares outstanding used to calculate basic and diluted earnings per common share	26,274,738