Brookline Bancorp (BRKL) 10-K 3 Mar 14 2013 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2013	Feb. 28, 2014
Document and Entity Information	'	'
Entity Registrant Name	'BROOKLINE BANCORP INC	'
Entity Central Index Key	'0001049782	'
Document Type	'10-K	'
Document Period End Date	31-Dec-13	'
Amendment Flag	'false	'
Current Fiscal Year End Date	'--12-31	'
Entity Well-known Seasoned Issuer	'No	'
Entity Voluntary Filers	'No	'
Entity Current Reporting Status	'Yes	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Public Float	'	$632.80
Entity Common Stock, Shares Outstanding	'	70,572,460
Document Fiscal Year Focus	'2013	'
Document Fiscal Period Focus	'FY	'

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
ASSETS	'	'
Cash and due from banks	$37,148	$78,441
Short-term investments	55,357	38,656
Total cash and cash equivalents	92,505	117,097
Investment securities available-for-sale	492,428	481,323
Investment securities held-to-maturity (fair value of $500 and $502, respectively)	500	500
Total investment securities	492,928	481,823
Loans held-for-sale	13,372	3,233
Total loans and leases	4,362,465	4,175,712
Allowance for loan and lease losses	-48,473	-41,152
Net loans and leases	4,313,992	4,134,560
Restricted equity securities	66,559	68,661
Premises and equipment, net of accumulated depreciation and amortization of $44,420 and $38,985, respectively	80,505	70,791
Deferred tax asset	31,710	27,197
Goodwill	137,890	137,890
Identified intangible assets, net of accumulated amortization of $22,895 and $18,272, respectively	16,887	21,510
Other real estate owned and repossessed assets, net	1,578	1,491
Other assets	77,180	83,281
Total assets	5,325,106	5,147,534
Non-interest-bearing deposits:	'	'
Demand checking accounts	707,023	623,274
Interest-bearing deposits:	'	'
NOW accounts	210,602	212,858
Savings accounts	494,734	515,367
Money market accounts	1,487,979	1,253,819
Certificate of deposit accounts	934,668	1,010,941
Total interest-bearing deposits	3,127,983	2,992,985
Total deposits	3,835,006	3,616,259
Borrowed funds:	'	'
Advances from the FHLBB	768,773	790,865
Other borrowed funds	43,782	63,104
Total borrowed funds	812,555	853,969
Mortgagors' escrow accounts	7,889	6,946
Accrued expenses and other liabilities	51,485	54,551
Total liabilities	4,706,935	4,531,725
Commitments and contingencies (Note 13)	'	'
Brookline Bancorp, Inc. stockholders' equity:	'	'
Common stock, $0.01 par value; 200,000,000 shares authorized; 75,744,445 shares and 75,749,825 shares issued, respectively	757	757
Additional paid-in capital	617,538	618,426
Retained earnings, partially restricted	64,903	53,358
Accumulated other comprehensive (loss) income	-7,915	3,483
Treasury stock, at cost; 5,171,985 shares and 5,373,733 shares, respectively	-59,826	-62,107
Unallocated common stock held by ESOP; 291,666 shares and 333,918 shares, respectively	-1,590	-1,820
Total Brookline Bancorp, Inc. stockholders' equity	613,867	612,097
Noncontrolling interest in subsidiary	4,304	3,712
Total stockholders' equity	618,171	615,809
Total liabilities and stockholders' equity	5,325,106	5,147,534
Commercial real estate loans	'	'
ASSETS	'	'
Total loans and leases	2,203,623	2,005,963
Allowance for loan and lease losses	-23,022	-20,018
Commercial loans	'	'
ASSETS	'	'
Total loans and leases	965,610	847,455
Allowance for loan and lease losses	-15,220	-10,655
Indirect automobile	'	'
ASSETS	'	'
Total loans and leases	400,531	542,344
Allowance for loan and lease losses	-3,924	-5,304
Consumer loans	'	'
ASSETS	'	'
Total loans and leases	792,701	779,950
Allowance for loan and lease losses	($3,375)	($2,545)

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]	'	'
Investment securities held to maturity, fair value (in dollars)	$500	$502
Premises and equipment, accumulated depreciation and amortization (in dollars)	44,420	38,985
Identified intangible assets, accumulated amortization (in dollars)	$22,895	$18,272
Common stock, par value (in dollars per share)	$0.01	$0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	75,744,445	75,749,825
Treasury stock, shares	5,171,985	5,373,733
Unallocated common stock held by ESOP, shares	291,666	333,918

Consolidated_Statements_of_Inc

Consolidated Statements of Income (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Interest and dividend income:	'	'	'
Loans and leases	$197,098	$203,711	$133,938
Debt securities	7,963	8,551	6,297
Marketable and restricted equity securities	1,212	730	195
Short-term investments	111	208	105
Total interest and dividend income	206,384	213,200	140,535
Interest expense:	'	'	'
Deposits	18,773	21,432	19,757
Borrowed funds	11,393	14,400	10,579
Total interest expense	30,166	35,832	30,336
Net interest income	176,218	177,368	110,199
Provision for credit losses	10,929	15,888	3,631
Provision for credit losses	165,289	161,480	106,568
Non-interest income:	'	'	'
Fees, charges and other income	15,240	16,475	5,653
Loss from investments in affordable housing projects	-1,812	-694	-671
Gain on sales of securities	397	926	80
Gain on sales of loans and leases	0	1,898	0
Total non-interest income	13,825	18,605	5,062
Non-interest expense:	'	'	'
Compensation and employee benefits	65,261	58,830	30,789
Occupancy	12,616	10,611	6,138
Equipment and data processing	16,899	14,540	9,144
Professional services	5,695	12,475	5,375
FDIC insurance	3,102	4,212	1,746
Advertising and marketing	3,003	2,984	1,376
Amortization of identified intangible assets	4,623	5,622	1,570
Other	11,261	11,101	6,787
Total non-interest expense	122,460	120,375	62,925
Income before provision for income taxes	56,654	59,710	48,705
Provision for income taxes	19,481	21,341	19,886
Net income before noncontrolling interest in subsidiary	37,173	38,369	28,819
Less net income attributable to noncontrolling interest in subsidiary	1,787	1,227	1,219
Net income attributable to Brookline Bancorp, Inc.	$35,386	$37,142	$27,600
Earnings per common share:	'	'	'
Basic (in dollars per share)	$0.51	$0.53	$0.47
Diluted (in dollars per share)	$0.51	$0.53	$0.47
Weighted average common shares outstanding during the year:	'	'	'
Basic (in shares)	69,808,164	69,702,417	58,633,627
Diluted (in shares)	69,883,924	69,746,256	58,636,431
Dividends declared per common share	$0.34	$0.34	$0.34

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement of Comprehensive Income [Abstract]	'	'	'
Net income before noncontrolling interest in subsidiary	$37,173	$38,369	$28,819
Other comprehensive income (loss), net of taxes:	'	'	'
Unrealized securities holding (losses) gains excluding non-credit gain on impairment of securities	-18,710	3,396	-488
Non-credit gain on impairment of securities	0	34	11
Income tax benefit (expense)	7,275	-1,308	177
Net unrealized securities holding (losses) gains before reclassification adjustments	-11,435	2,122	-300
Less reclassification adjustments for securities gains included in net income:	'	'	'
Gain on sales of securities, net	397	926	80
Income tax expense	-142	-328	-29
Net reclassification adjustments for securities gains included in net income	255	598	51
Net unrealized securities holding (losses) gains	-11,690	1,524	-351
Postretirement benefits:	'	'	'
Adjustment of accumulated obligation for postretirement benefits	468	-10	-57
Income tax (expense) benefit	-176	6	23
Net adjustment of accumulated obligation for postretirement benefits	292	-4	-34
Net other comprehensive (loss) income	-11,398	1,520	-385
Comprehensive income	25,775	39,889	28,434
Net income attributable to noncontrolling interest in subsidiary	1,787	1,227	1,219
Comprehensive income attributable to Brookline Bancorp, Inc.	$23,988	$38,662	$27,215

Consolidated_Statements_of_Cha

Consolidated Statements of Changes in Stockholders' Equity (USD $)	Total	Total Brookline Bancorp, Inc. Stockholders' Equity	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Unallocated Common Stock Held by ESOP	Noncontrolling Interest in Subsidiary
In Thousands, unless otherwise specified
Balance at Dec. 31, 2010	$497,948	$495,443	$644	$524,515	$32,357	$2,348	($62,107)	($2,314)	$2,505
Increase (Decrease) in Stockholders' Equity	'	'	'	'	'	'	'	'	'
Net income attributable to Brookline Bancorp, Inc.	27,600	27,600	'	'	27,600	'	'	'	'
Net income attributable to noncontrolling interest in subsidiary	1,219	'	'	'	'	'	'	'	1,219
Dividend distribution to owners of noncontrolling interest in subsidiary	-585	'	'	'	'	'	'	'	-585
Issuance of units of ownership to minority owner of subsidiary	102	'	'	'	'	'	'	'	102
Minority owners' interest in deferred tax asset related to subsidiary	159	'	'	'	'	'	'	'	159
Other comprehensive income (loss)	-385	-385	'	'	'	-385	'	'	'
Common stock dividends of $0.34 per share	-19,964	-19,964	'	'	-19,964	'	'	'	'
Expense of stock options granted	47	47	'	47	'	'	'	'	'
Income tax benefit from vesting of recognition and retention plan shares and dividend distributions on allocated ESOP shares	79	79	'	79	'	'	'	'	'
Compensation under recognition and retention plan	364	364	'	364	'	'	'	'	'
Common stock held by ESOP committed to be released (42,252, 44,292 and 46,207 shares) for the year ended 2013, 2012 and 2011, respectively	418	418	'	166	'	'	'	252	'
Balance at Dec. 31, 2011	507,002	503,602	644	525,171	39,993	1,963	-62,107	-2,062	3,400
Increase (Decrease) in Stockholders' Equity	'	'	'	'	'	'	'	'	'
Net income attributable to Brookline Bancorp, Inc.	37,142	37,142	'	'	37,142	'	'	'	'
Net income attributable to noncontrolling interest in subsidiary	1,227	'	'	'	'	'	'	'	1,227
Dividend distribution to owners of noncontrolling interest in subsidiary	-915	'	'	'	'	'	'	'	-915
Issuance of shares of common stock (10,997,840 shares)	92,822	92,822	113	92,709	'	'	'	'	'
Other comprehensive income (loss)	1,520	1,520	'	'	'	1,520	'	'	'
Common stock dividends of $0.34 per share	-23,777	-23,777	'	'	-23,777	'	'	'	'
Compensation under recognition and retention plan	546	546	'	546	'	'	'	'	'
Common stock held by ESOP committed to be released (42,252, 44,292 and 46,207 shares) for the year ended 2013, 2012 and 2011, respectively	242	242	'	0	'	'	'	242	'
Balance at Dec. 31, 2012	615,809	612,097	757	618,426	53,358	3,483	-62,107	-1,820	3,712
Increase (Decrease) in Stockholders' Equity	'	'	'	'	'	'	'	'	'
Net income attributable to Brookline Bancorp, Inc.	35,386	35,386	'	'	35,386	'	'	'	'
Net income attributable to noncontrolling interest in subsidiary	1,787	'	'	'	'	'	'	'	1,787
Dividend distribution to owners of noncontrolling interest in subsidiary	-1,195	'	'	'	'	'	'	'	-1,195
Other comprehensive income (loss)	-11,398	-11,398	'	'	'	-11,398	'	'	'
Common stock dividends of $0.34 per share	-23,841	-23,841	'	'	-23,841	'	'	'	'
Compensation under recognition and retention plan	1,393	1,393	'	1,393	'	'	'	'	'
Common stock held by ESOP committed to be released (42,252, 44,292 and 46,207 shares) for the year ended 2013, 2012 and 2011, respectively	230	230	'	-2,281	'	'	2,281	230	'
Balance at Dec. 31, 2013	$618,171	$613,867	$757	$617,538	$64,903	($7,915)	($59,826)	($1,590)	$4,304

Consolidated_Statements_of_Cha1

Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement of Stockholders' Equity [Abstract]	'	'	'
Issuance of shares of common stock, shares	'	10,997,840	'
Common stock dividends, per share (in dollars per share)	$0.34	$0.34	$0.34
Common stock held by ESOP committed to be released, shares	42,252	44,292	46,207

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:	'	'	'
Net income attributable to Brookline Bancorp, Inc.	$35,386	$37,142	$27,600
Adjustments to reconcile net income to net cash provided from operating activities:	'	'	'
Net income attributable to noncontrolling interest in subsidiary	1,787	1,227	1,219
Provision for credit losses	10,929	15,888	3,631
Origination of loans and leases to be sold	-52,485	-101,286	-46,555
Proceeds from loans and leases sold	56,389	104,029	41,687
Proceeds from sales of other real estate owned and other repossessed assets	11,857	1,572	1,711
Deferred income tax expense	2,444	663	784
Depreciation of premises and equipment	6,291	3,733	2,061
Amortization of securities premiums and discounts, net	3,200	4,486	2,344
Amortization of deferred loan and lease origination costs, net	7,749	10,121	9,775
Amortization of identified intangible assets	4,623	5,622	1,570
(Accretion) amortization of acquisition fair value adjustments, net	-6,193	-12,121	658
Gain on sale of loans and leases held for sale	-671	-718	-392
Gain on sale of loans and leases	0	-1,898	0
Gain on sale of securities	-397	-926	-80
Gain on sale of other real estate owned and repossessed assets	-2	-194	0
Write-down of other real estate owned and repossessed assets	263	73	869
Compensation under recognition and retention plans	1,393	546	364
Expense of restricted stock plans, net of income tax	584	625	126
Loss from investments in affordable housing projects	1,812	694	671
ESOP shares committed to be released	230	242	418
Net change in:	'	'	'
Cash surrender value of bank-owned life insurance	-1,093	-1,165	0
Other assets	5,398	-11,621	-4,097
Accrued expenses and other liabilities	-3,434	2,577	1,869
Net cash provided from operating activities	86,060	59,311	46,233
Cash flows from investing activities:	'	'	'
Proceeds from sales of securities available-for-sale	1,210	166,201	124
Proceeds from maturities, calls, and principal repayments of securities available-for-sale	137,275	207,512	145,374
Purchases of securities available-for-sale	-171,231	-326,104	-45,361
Proceeds from principal repayments of securities held-to-maturity	2,107	0	0
Purchase of restricted-equity and other securities	-5	-15,505	0
Proceeds from sales of loans and leases	0	21,904	0
Net increase in loans and leases	-220,021	-352,893	-273,394
Acquisitions, net of cash and cash equivalents acquired	0	-89,258	5,792
Monies in escrow - Bancorp Rhode Island, Inc. acquisition	0	112,983	-112,983
Purchase of premises and equipment	-16,443	-23,664	-19,910
Sale of premises and equipment	260	0	0
Proceeds from redemption of restricted securities (FHLBB stock)	0	2,003	0
Net cash used in investing activities	-266,848	-296,821	-300,358
Cash flows from financing activities:	'	'	'
Increase in demand checking, NOW, savings and money market accounts	295,020	312,644	273,693
Decrease in certificates of deposit	-76,620	-80,879	-44,734
Proceeds from FHLBB advances	2,363,200	3,007,883	3,973,549
Repayment of FHLBB advances	-2,381,917	-2,992,101	-3,865,689
Proceeds from payment of federal funds purchased	0	0	-13,000
Repayment of subordinated debt	-3,000	0	-13,000
(Decrease) increase in other borrowed funds	-16,394	25,023	4,018
Increase in mortgagors' escrow accounts	943	433	123
Payment of dividends on common stock	-23,841	-23,777	-19,964
Payment of dividends to owners of noncontrolling interest in subsidiary	-1,195	-915	-585
Purchase of additional ownership interest in subsidiary	0	0	102
Net cash provided from financing activities	156,196	248,311	294,513
Net (decrease) increase in cash and cash equivalents	-24,592	10,801	40,388
Cash and cash equivalents at beginning of year	117,097	106,296	65,908
Cash and cash equivalents at end of year	92,505	117,097	106,296
Cash paid during the year for:	'	'	'
Interest on deposits, borrowed funds and subordinated debt	34,303	40,682	32,029
Income taxes	19,137	20,570	20,607
Non-cash investing activities:	'	'	'
Transfer from loans to loan held-for-sale	13,372	0	0
Transfer from loans to other real estate owned	12,205	386	2,536
Bancorp Rhode Island, Inc.:	'	'	'
Acquisition	'	'	'
Fair value of assets acquired, net of cash and cash equivalents acquired	0	1,571,817	0
Fair value of liabilities assumed	0	1,481,535	0
First Ipswich Bancorp:	'	'	'
Acquisition	'	'	'
Fair value of assets acquired, net of cash and cash equivalents acquired	0	0	246,186
Fair value of liabilities assumed	$0	$0	$251,978

Basis_of_Presentation

Basis of Presentation	12 Months Ended
	Dec. 31, 2013
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Basis of Presentation	'
	Basis of Presentation
	Overview
	Brookline Bancorp, Inc. (the "Company") is a bank holding company (within the meaning of the Bank Holding Company Act of 1956, as amended) and the parent of Brookline Bank, a Massachusetts-chartered savings bank; Bank Rhode Island ("BankRI"), a Rhode Island-chartered bank; and First Ipswich Bank ("First Ipswich" and formerly known as the First National Bank of Ipswich), a Massachusetts-chartered trust company (collectively referred to as the "Banks"). The Company is also the parent of Brookline Securities Corp. ("BSC"). The Company's primary business is to provide commercial, business and retail banking services to its corporate, municipal and individual customers through its banks and non-bank subsidiaries.
	Brookline Bank, which includes its wholly-owned subsidiaries BBS Investment Corp. and Longwood Securities Corp., and its 84.8%-owned subsidiary, Eastern Funding LLC ("Eastern Funding"), operates 23 full-service banking offices in Brookline, Massachusetts, and the greater Boston metropolitan area. BankRI, which includes its wholly-owned subsidiaries BRI Investment Corp., Macrolease Corporation ("Macrolease"), Acorn Insurance Agency and BRI Realty Corp., operates 18 full-service banking offices in Providence County, Kent County and Washington County, Rhode Island. First Ipswich, which includes its wholly-owned subsidiaries First Ipswich Securities II Corp., First Ipswich Insurance Agency and FNBI Realty, operates 6 full-service banking offices on the north shore of eastern Massachusetts and in the Boston metropolitan area.
	The Company's activities include acceptance of commercial business, municipal and retail deposits, origination of mortgage loans on commercial and residential real estate located principally in Massachusetts and Rhode Island, origination of commercial loans and leases to small- and mid-sized businesses, origination of indirect automobile loans, investment in debt and equity securities, and the offering of cash management and investment advisory services. The Company also provides specialty equipment financing through its subsidiaries Eastern Funding, which is based in New York City, and Macrolease, which is based in Plainview, New York.
	The Company and the Banks are subject to competition from other financial and non-financial institutions and are supervised, examined and regulated by the Board of Governors of the Federal Reserve System ("FRB"). As Massachusetts-chartered member banks, Brookline Bank and First Ipswich are also subject to regulation under the laws of the Commonwealth of Massachusetts and the jurisdiction of the Massachusetts Division of Banks. BankRI is subject to regulation under the laws of the State of Rhode Island and the jurisdiction of the Banking Division of the Rhode Island Department of Business Regulation.
	The Federal Deposit Insurance Corporation ("FDIC") offers insurance coverage on all deposits up to $250,000 per depositor for all three Banks. As FDIC-insured depository institutions, all three Banks are also secondarily subject to supervision, examination and regulation by the FDIC. Additionally, as a Massachusetts-chartered savings bank, Brookline Bank is also insured by the Depositors Insurance Fund ("DIF"), a private industry-sponsored insurance company. The DIF insures savings bank deposits in excess of the FDIC insurance limits. As such, Brookline Bank offers 100% insurance on all deposits as a result of a combination of insurance from the FDIC and the DIF.
	Basis of Financial Statement Presentation
	The Company's consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles ("GAAP") as set forth by the Financial Accounting Standards Board ("FASB") in its Accounting Standards Codification and through the rules and interpretive releases of the Securities and Exchange Commission ("SEC") under the authority of federal securities laws.
	The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All significant intercompany transactions and balances are eliminated in consolidation.
	In preparing these consolidated financial statements, management is required to make significant estimates and assumptions that affect the reported amounts of assets, liabilities, income, expenses and disclosure of contingent assets and liabilities. Actual results could differ from those estimates based upon changing conditions, including economic conditions and future events. Material estimates that are particularly susceptible to significant change in the near-term include the determination of the allowance for loan and lease losses, the determination of fair market values of assets and liabilities, including acquired loans, the review of goodwill and intangibles for impairment and the review of deferred tax assets for valuation allowance.
	The judgments used by management in applying these critical accounting policies may be affected by a further and prolonged deterioration in the economic environment, which may result in changes to future financial results. For example, subsequent evaluations of the loan and lease portfolio, in light of the factors then prevailing, may result in significant changes in the allowance for loan and lease losses in future periods, and the inability to collect outstanding principal may result in increased loan and lease losses.
	Reclassification
	Certain previously reported amounts have been reclassified to conform to the current year's presentation. These reclassifications did not change stockholders' equity or net income reported.
	Cash and Cash Equivalents
	For purposes of reporting asset balances and cash flows, cash and cash equivalents includes cash on hand and due from banks (including cash items in process of clearing), interest-bearing deposits with banks, federal funds sold, money market mutual funds and other short-term investments with original maturities of three months or less.
	Investment Securities
	Investment securities, other than those reported as short-term investments, are classified at the time of purchase as "available for sale," "held to maturity," or "trading." Classification is periodically re-evaluated for consistency with the Company's goals and objectives. Equity investments in the Federal Home Loan Bank of Boston ("FHLBB") and the Federal Reserve Bank of Boston are discussed in more detail in Note 5, "Restricted Equity Securities."
	Investment Securities Available-for-Sale and Held-to-Maturity
	Securities for which the Company has the positive intent and ability to hold to maturity are classified as held-to-maturity and carried at amortized cost. Those securities held for indefinite periods of time but not necessarily to maturity are classified as available-for-sale. Securities held for indefinite periods of time include securities that management intends to use as part of its asset/liability, liquidity, and/or capital management strategies and may be sold in response to changes in interest rates, maturities, asset/liability mix, liquidity needs, regulatory capital needs or other business factors. Securities available-for-sale are carried at estimated fair value, primarily obtained from a third-party pricing service, with unrealized gains and losses reported on an after-tax basis in stockholders' equity as accumulated other comprehensive income or loss. As of December 31, 2013 and 2012, the Company did not make any adjustments to the prices provided by the third-party pricing service.
	Security transactions are recorded on the trade date. Realized gains and losses are determined using the specific identification method and are recorded in non-interest income. Interest and dividends on securities are recorded using the accrual method. Premiums and discounts on securities are amortized or accreted into interest income using the level-yield method over the remaining period to contractual maturity, adjusted for the effect of actual prepayments in the case of mortgage-backed securities ("MBSs") and collateralized mortgage obligations ("CMOs"). These estimates of prepayment assumptions are made based upon the actual performance of the underlying security, current interest rates, the general market consensus regarding changes in mortgage interest rates, the contractual repayment terms of the underlying loans, the priority rights of the investors to the cash flows from the mortgage securities and other economic conditions. When differences arise between anticipated prepayments and actual prepayments, the effective yield is recalculated to reflect actual payments to date and anticipated future payments. Unamortized premium or discount is adjusted to the amount that would have existed had the new effective yield been applied since purchase, with a corresponding charge or credit to interest income.
	Management evaluates securities for other-than-temporary impairment ("OTTI") on a periodic basis. Factors considered in determining whether an impairment is other-than-temporary include: (1) the length of time and the extent to which the fair value has been less than cost, (2) the financial condition and near-term prospects of the issuer and (3) the intent and ability of the Company to hold the investment for a period of time sufficient to allow for any anticipated recovery in fair value. The Company records an other-than-temporary loss in an amount equal to the entire difference between the fair value and amortized cost if (1) the Company intends to sell an impaired security, (2) it is more likely than not that the Company will be required to sell the security before its amortized costs or (3) for debt securities, the present value of expected future cash flows is not sufficient to recover the entire amortized cost basis. If a security is determined to be other-than-temporarily impaired but the Company does not intend to sell the security, only the credit portion of the estimated loss is recognized in earnings, with the other portion of the loss recognized in other comprehensive income.
	Restricted Securities
	The Company owns investments in the stock of the FHLBB, the Federal Reserve Bank of Boston and a small amount of other restricted securities. No ready market exists for these stocks, and they have no quoted market values. The Banks, as members of the FHLBB, are required to maintain investments in the capital stock of the FHLBB equal to their membership base investments plus an activity-based investment determined according to the Banks' level of outstanding FHLBB advances. Federal Reserve Bank of Boston stock was purchased at par and is redeemable at par. The Company reviews for impairment of these securities based on the ultimate recoverability of the cost basis in the stock. At December 31, 2013, no impairment has been recognized.
	Loans
	Originated Loans
	Loans the Company originates for the portfolio, and for which it has the intent and ability to hold to maturity, are reported at amortized cost, inclusive of deferred loan origination fees and expenses, less unadvanced funds due borrowers on loans and the allowance for loan and lease losses.
	Interest income on loans and leases originated for the portfolio is accrued on unpaid principal balances as earned. Loan origination fees and direct loan origination costs are deferred, and the net fee or cost is recognized in interest income using the interest method. Deferred loan origination costs include payments to dealers originating indirect automobile loans. The difference between the rate charged by a dealer to originate an indirect automobile loan and the "buy rate," or the rate earned by the Company, is referred to as the "spread." The computed dollar value of the spread paid to a dealer is amortized as a charge to income over the life of the loan on a level-yield basis. Deferred amounts are recognized for fixed-rate loans over the contractual life of the loans and for adjustable-rate loans over the period of time required to adjust the contractual interest rate to a yield approximating a market rate at the origination date. If a loan is prepaid, the unamortized portion of the loan origination costs, including those indirect-automobile-related costs not subject to rebate from the dealer, is charged to income.
	Loans Held-for-Sale
	Management identifies and designates certain newly originated loans for sale to specific financial institutions, subject to the underwriting criteria of those financial institutions. These loans are held for sale and are carried at the lower of cost or market as determined in the aggregate. Deferred loan fees and costs are included in the determination of the gain or loss on sale.
	Acquired Loans
	Acquired loans that have evidence of deterioration of credit quality since origination and for which it is probable, at acquisition, that the Corporation will be unable to collect all contractually required payments receivable are initially recorded at fair value (as determined by the present value of expected future cash flows) with no valuation allowance. The difference between the undiscounted cash flows expected at acquisition and the recorded fair value of the loan, or the “accretable yield,” is recognized as interest income on a level-yield method over the life of the loan. Contractually required payments for interest and principal that exceed the undiscounted cash flows expected at acquisition, or the “nonaccretable difference,” are not recognized as a yield adjustment or as a loss accrual or a valuation allowance. Increases in expected cash flows subsequent to the initial investment are recognized prospectively through adjustment of the yield on the loan over its remaining life. Decreases in expected cash flows are recognized as impairment. Valuation allowances on these impaired loans reflect only losses incurred after the acquisition (meaning the present value of all cash flows expected at acquisition that ultimately are not to be received).
	Nonperforming Loans
	Nonaccrual Loans
	Accrual of interest on loans generally is discontinued when contractual payment of principal or interest becomes past due 90 days or, if in management's judgment, reasonable doubt exists as to the full timely collection of interest. Exceptions may be made if the loan has matured and is in the process of renewal or is well-secured and in the process of collection. When a loan is placed on nonaccrual status, interest accruals cease and uncollected accrued interest is reversed and charged against current interest income. Interest payments on nonaccrual loans are applied to principal. Loans are returned to accrual status when principal and interest payments are current, full collectability of principal and interest is reasonably assured and a consistent record of at least six consecutive months of performance has been achieved.
	Impaired Loans
	A loan is considered to be impaired when, based on current information and events, it is probable that the Company will be unable to collect all amounts due (both interest and principal) according to the contractual terms of the loan agreement. Smaller-balance, homogeneous loans that are evaluated collectively for impairment, such as indirect automobile, residential, home equity and other consumer loans are specifically excluded from the impaired loan portfolio except where the loan is classified as a troubled debt restructuring. The Company has defined the population of impaired loans to include nonaccrual loans and troubled debt restructured loans.
	The value of an impaired loan is measured based upon the present value of expected future cash flows discounted at the loan's effective interest rate, or the fair value of the collateral if the loan is collateral-dependent and its payment is expected solely based on the underlying collateral. For impaired loans deemed collateral dependent, where impairment is measured using the fair value of the collateral, the Company will either obtain a new appraisal or use another available source of collateral assessment to determine a reasonable estimate of the fair value of the collateral.
	Interest collected on impaired loans is either applied against principal or reported as income according to management's judgment as to the collectability of principal. If management does not consider a loan ultimately collectible within an acceptable time frame, payments are applied as principal to reduce the loan balance. If full collection of the remaining recorded investment should subsequently occur, interest receipts are recorded as interest income on a cash basis.
	Troubled Debt Restructured Loans
	In cases where a borrower experiences financial difficulties and the Company makes certain concessionary modifications to contractual terms, the loan is classified as a troubled debt restructured loan. In determining whether a debtor is experiencing financial difficulties, the Company considers, among other factors, if the debtor is in payment default or is likely to be in payment default in the foreseeable future without the modification, the debtor declared or is in the process of declaring bankruptcy, there is substantial doubt that the debtor will continue as a going concern, the debtor's entity-specific projected cash flows will not be sufficient to service its debt, or the debtor cannot obtain funds from sources other than the existing creditors at market terms for debt with similar risk characteristics.
	Modifications may include interest-rate reductions, short-term (defined as one year or less) changes in payment structure to interest-only payments, short-term extensions of the loan's original contractual term or, less frequently, principal forgiveness, interest capitalization, forbearance and other actions intended to minimize the economic loss and to avoid foreclosure or repossession of collateral. Typically, troubled debt restructurings are placed on nonaccrual status and reported as nonperforming loans. Generally, a nonaccrual loan that is restructured remains on nonaccrual for a period of six months to demonstrate the borrower can meet the restructured terms; however, performance prior to the restructuring, or significant events that coincide with the restructuring, are considered in assessing whether the borrower can meet the new terms and may result in the loan being returned to accrual status at the time of restructuring or after a shorter performance period. If the borrower's ability to meet the revised payment schedule is not reasonably assured, the loan remains classified as a nonaccrual loan.
	Loans restructured at an interest rate equal to or greater than that of a new loan with comparable risk at the time of the loan agreement is modified may be excluded from restructured loan disclosures in years subsequent to the restructuring if they are in compliance with the modified terms.
	Allowance for Loan and Lease Losses
	Additions to the allowance for loan and lease losses are made by charges to the provision for credit losses. Losses on loans and leases are charged off against the allowance when all or a portion of a loan or lease is considered uncollectible. Subsequent recoveries on loans previously charged off, if any, are credited to the allowance when realized
	The allowance for loan and lease losses consists of general, specific and unallocated reserves and reflects management's estimate of probable loan and lease losses inherent in the loan portfolio at the balance sheet date. Management uses a consistent and systematic process and methodology to evaluate the adequacy of the allowance for loan and lease losses on a quarterly basis. The allowance is calculated by loan category, including commercial real estate loans, commercial loans and leases, indirect automobile loans and consumer loans; with each of these categories further segregated into classes. A formula-based credit evaluation approach is applied to each group, coupled with an analysis of certain loans for impairment.
	The process to determine the allowance for loan and lease losses requires management to exercise considerable judgment regarding the risk characteristics of the loan portfolio categories and the effect of relevant internal and external factors. The reasonableness of prior judgments is evaluated on a quarterly basis by comparison of estimated loan and lease losses to loan and lease losses actually incurred. In addition, various regulatory agencies, as an integral part of their examination process, periodically review the Company's allowance for loan and lease losses. Such agencies may require the Company to change the allowance based on their judgments of information available to them at the time of their examination.
	General Allowance
	The general allowance related to loans collectively evaluated for impairment is determined using a formula-based approach utilizing the risk ratings of individual credits and loss factors derived from historic portfolio loss rates. Other relevant qualitative factors include, but are not limited to, historic levels and trends in loan charge-offs and recoveries; past-due loans; risk-rated loans; classified loans and impaired loans; the pace of loan growth; underwriting policies and adherence to such policies; changes in credit concentration; the experience of lending personnel and management; trends in the economy and employment; business conditions; industry conditions; and political, legislative and regulatory changes. The general allowance related to the acquired loans collectively evaluated for impairment are determined based upon the degree, if any, of deterioration in the pooled loans subsequent to acquisition. The qualitative factors used in the determination are the same as those used for originated loans.
	Specific Allowance
	Specific valuation allowances are established for impaired originated loans with book values greater than the discounted present value of expected future cash flows or, in the case of collateral-dependent impaired loans, for any excess of a loan's book balance and the fair value of its underlying collateral. Specific valuation allowances are established for acquired loans with deterioration in the discounted present value of expected further cash flows since acquisitions or, in the case of collateral dependent impaired loans, for any increase in the excess of a loan's book balance greater than the fair value of its underlying collateral. A specific valuation allowance for losses on troubled debt restructured loans is determined by comparing the net carrying amount of the troubled debt restructured loan with the restructured loan's cash flows discounted at the original effective rate. Impaired loans are reviewed quarterly with adjustments made to the calculated reserve as deemed necessary.
	Unallocated Allowance
	Determination of the unallocated portion of the allowance is a subjective process. Management believes the unallocated allowance is an important component of the total allowance because it addresses the probable inherent risk of loss that exists in that part of the Company's loan portfolio with repayment terms that extend over many years. It also helps to minimize the risk related to the margin of imprecision inherent in the estimation of the allocated components of the allowance. The Company has not allocated the unallocated portion of the allowance to the various loan categories and classes because such an allocation would imply a degree of precision that does not exist.
	Liability for Unfunded Commitments
	In the ordinary course of business, the Company enters into commitments to extend credit, commercial letters of credit, and standby letters of credit. Such financial instruments are recorded in the financial statements when they become payable. The credit risk associated with these commitments is evaluated in a manner similar to the allowance for loan losses.
	Premises and Equipment
	Premises and equipment are carried at cost less accumulated depreciation and amortization, except for land which is carried at cost. Premises and equipment are depreciated using the straight-line method over the estimated useful life of the assets. Leasehold improvements are amortized using the straight-line method over the shorter of the lease term or the estimated useful life of the improvements.
	Costs related to internal-use software development projects that provide significant new functionality are capitalized. Internal-use software is software acquired or modified solely to meet the Company's needs and for which there is no plan to market the software externally. Direct and indirect costs associated with the application development stage of internal use software are capitalized until such time that the software is substantially complete and ready for its intended use. Capitalized costs are amortized on a straight-line basis over the remaining estimated life of the software. Computer software and development costs incurred in the preliminary project stage, as well as training and maintenance costs, are expensed as incurred.
	Bank-Owned Life Insurance
	The Company acquired bank-owned life insurance ("BOLI") plans as part of its acquisitions of First Ipswich and BankRI. BOLI represents life insurance on the lives of certain current and former employees who have provided positive consent allowing their employer to be the beneficiary of such policies. BankRI and First Ipswich are the beneficiaries of their respective policies. BankRI and First Ipswich utilize BOLI as tax-efficient financing for their benefit obligations to their employees, including their retirement obligations and Supplemental Executive Retirement Plans ("SERPs").
	Since BankRI and First Ipswich are the primary beneficiaries of their respective insurance policies, increases in the cash value of the policies, as well as insurance proceeds received, are recorded in non-interest income and are not subject to income taxes. BOLI is recorded at the cash value of the policies, less any applicable cash surrender charges, and is reflected as an asset in the accompanying consolidated balance sheets. The Company reviews the financial strength of the insurance carriers prior to the purchase of BOLI to ensure minimum credit ratings of at least investment grade. The financial strength of the carriers is reviewed at least annually and BOLI with any individual carrier is limited to 10% of capital.
	Goodwill and Other Identified Intangible Assets
	Goodwill represents the excess of the cost of an acquisition over the fair value of the net assets acquired. Goodwill is not subject to amortization. Identified intangible assets are assets resulting from acquisitions that are being amortized over their estimated useful lives. The recoverability of goodwill and identified intangible assets is evaluated for impairment at least annually. As part of this evaluation, the Company makes a qualitative assessment of whether it is more likely than not that the fair value of an acquired asset is greater than its carrying amount. Pursuant to FASB Accounting Standards Update ("ASU") 2011-8, adopted in January 2012, if the Company concludes that it is more likely than not that the fair value of an acquired asset is greater than its carrying amount, no further testing is necessary. If, however, the Company concludes that it is more likely than not that the fair value of an acquired asset is less than its carrying value, the Company performs a two-step quantitative impairment test to determine whether the asset is impaired. If impairment is deemed to have occurred, the amount of impairment is charged to expense when identified.
Other Real Estate Owned and Repossessed Assets
OREO consists of property acquired through foreclosure, real estate acquired through acceptance of a deed in lieu of foreclosure and loans determined to be substantively repossessed. Real estate loans that are substantively repossessed include only those loans for which the Company has taken possession of the collateral. OREO and repossessed assets which consist of vehicles and equipment, if any, are recorded initially at estimated fair value less costs to sell, resulting in a new cost basis. The amount by which the recorded investment in the loan exceeds the fair value (net of estimated cost to sell) of the foreclosed or repossessed asset is charged to the allowance for loan and lease losses. Such evaluations are based on an analysis of individual properties/assets as well as a general assessment of current real estate market conditions. Subsequent declines in the fair value of the foreclosed or repossessed asset below the new cost basis are recorded through the use of a valuation allowance. Subsequent increases in the fair value are recorded as reductions in the allowance, but not below zero. Rental revenue received on foreclosed or repossessed assets is included in other non-interest income, whereas operating expenses and changes in the valuation allowance relating to foreclosed and repossessed assets are included in other non-interest expense. Certain costs used to improve such properties are capitalized. Gains and losses from the sale of OREO and repossessed vehicles and equipment are reflected in non-interest expense when realized. Together with nonperforming loans, OREO and repossessed assets comprise nonperforming assets.
Derivatives
The Company enters into interest rate swap agreements as part of the Company's interest-rate risk management strategy for certain assets and liabilities and not for speculative purposes. Based on the Company's intended use for the interest rate swap at inception, the Company designates the derivative as either an economic hedge of an asset or liability or a hedging instrument subject to the hedge accounting provisions of FASB ASC Topic 815, "Derivatives and Hedging."
Interest rate swaps designated as economic hedges are recorded at fair value within other assets or liabilities. Changes in the fair value of these derivatives are recorded directly through earnings at each reporting period.
Transfer of Financial Assets
Transfers of financial assets are accounted for as sales when control over the assets has been surrendered. Control over transferred assets is deemed to be surrendered when (1)the assets have been isolated from the Company, (2)the transferee obtains the right (free of conditions that constrain it from taking advantage of that right) to pledge or exchange the transferred assets, and (3)the Company does not maintain effective control over the transferred assets through an agreement to repurchase them before their maturity.
Securities Sold under Agreements to Repurchase
The Company enters into sales of securities under agreements to repurchase with the Banks' commercial customers. These agreements are treated as financings, and the obligations to repurchase securities sold are reflected as a liability in the consolidated balance sheets. Securities pledged as collateral under agreements to repurchase are reflected as assets in the accompanying consolidated balance sheets.
Employee Benefits
Costs related to the Company's 401(k) plans are recognized over the vesting period or charged against current operations in the year made depending on the plan. Costs related to the Company's nonqualified deferred compensation plan, SERPs and postretirement benefits are recognized over the vesting period or the related service periods of the participating employees. Changes in the funded status of postretirement benefits are recognized through comprehensive income in the year in which changes occur.
Compensation expense for the Employee Stock Ownership Plan ("ESOP") is recorded at an amount equal to the shares allocated by the ESOP multiplied by the average fair market value of the shares during the year. The Company recognizes compensation expense ratably over the year based upon the Company's estimate of the number of shares expected to be allocated by the ESOP. The difference between the average fair market value and the cost of the shares allocated by the ESOP is recorded as an adjustment to additional paid-in capital.
The fair value of restricted common stock awards and stock option grants is determined as of the grant date and is recorded as compensation expense over the period in which the shares of common stock and stock options vest. Forfeitures are estimated in determining compensation expense.
Fair Value Measurements
ASC 820-10, "Fair Value Measurements and Disclosures," defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. A fair value measurement assumes that the transaction to sell the asset or transfer the liability occurs in the principal market for the asset or liability or, in the absence of a principal market, the most advantageous market for the asset or liability. The price in the principal (or most advantageous) market used to measure the fair value of the asset or liability is not adjusted for transaction costs. An orderly transaction is a transaction that assumes exposure to the market for a period prior to the measurement date to allow for marketing activities that are usual and customary for transactions involving such assets and liabilities. It is not a forced transaction. Market participants are buyers and sellers in the principal market that are independent, knowledgeable, able to transact and willing to transact.
A fair-value hierarchy for valuation inputs that gives the highest priority to quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs are included in ASC 820. The fair value hierarchy is as follows:
Level 1: Inputs are unadjusted quoted prices in active markets for assets and liabilities identical to those reported at fair value.
Level 2: Inputs other than quoted prices included within Level 1. Level 2 inputs are observable either directly or indirectly. These inputs might include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (such as interest rates, volatilities, prepayment speeds, credit risks, etc.) or inputs that are derived principally from or corroborated by market data by correlation or other means.
Level 3: Inputs are unobservable inputs for an asset or liability that reflect an entity's own assumptions about the assumptions that market participants would use in pricing the assets or liabilities. These inputs are used to determine fair value only when observable inputs are not available.
Earnings per Common Share
Basic earnings per share ("EPS") is computed by dividing net income by the weighted average number of shares of common stock outstanding for the applicable period, exclusive of unearned ESOP shares and unvested restricted stock. Diluted EPS is calculated after adjusting the denominator of the basic EPS calculation for the effect of all potential dilutive common shares outstanding during the period. The dilutive effects of options and unvested restricted stock awards are computed using the "treasury stock" method, the results of which are not materially different from those calculated using the “two-class” method.
Income Taxes
Income taxes are accounted for under the asset and liability method. Under this method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases.
Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date.
Tax positions that are more likely than not to be sustained upon a tax examination are recognized in the Company's financial statements to the extent that the benefit is greater than 50% likely of being recognized. Interest resulting from underpayment of income taxes is classified as income tax expense in the first period the interest would begin accruing according to the provision of the relevant tax law. Penalties resulting from underpayment of income taxes are classified as income tax expense in the period for which the Company claims or expects to claim an uncertain tax position or in the period in which the Company's judgment changes regarding an uncertain tax position.
Tax credits generated from the refurbishment of the corporate headquarters and investments in affordable housing projects are reflected in earnings when realized for federal income tax purposes.
Treasury Stock
Shares repurchased under the Company's share repurchase programs were purchased in open-market transactions and are held as treasury stock. Treasury stock also consists of common stock withheld to satisfy federal, state and local income tax withholding requirements for vested employee restricted stock awards. All treasury stock is held at cost.
Segment Reporting
An operating segment is defined as a component of a business for which separate financial information is available that is evaluated regularly by the chief operating decision-maker in deciding how to allocate resources and evaluate performance. The Company is a bank holding company with subsidiaries engaged in the business of banking and activities closely related to banking. The Company's banking business provided substantially all of its total revenues and pre-tax income in 2013, 2012 and 2011. Therefore, the Company has determined there to be a single segment.
Recent Accounting Pronouncements
In February 2013, FASB issued Accounting Standards Update (“ASU”) No. 2013-01, Clarifying the Scope of Disclosures about Offsetting Assets and Liabilities. This ASU clarifies the scope of offsetting disclosure requirements in ASU 2011-11, Balance Sheet (Topic 210): Disclosures about Offsetting Assets and Liabilities. Under ASU 2013-01, the disclosure requirements would apply to derivative instruments accounted for in accordance with ASC 815, including bifurcated embedded derivatives, repurchase agreements and reverse repurchase agreements, and securities borrowing and securities lending arrangements that are either offset on the balance sheet or subject to an enforceable master netting arrangement or similar agreement. Entities with other types of financial assets and financial liabilities subject to a master netting arrangement or similar agreement also are affected because these amendments make them no longer subject to the disclosure requirements in ASU No. 2011-11. Effective January 1, 2013, companies are required to disclose (a) gross amounts of recognized assets and liabilities; (b) gross amounts offset in the statement of financial position; (c) net amounts of assets and liabilities presented in the statement of financial position; (d) gross amount subject to enforceable master netting agreement not offset in the statements of financial position; and (e) net amounts after deducting (d) from (c). The disclosure should be presented in tabular format (unless another format is more appropriate) separately for assets and liabilities. The intent of the new disclosure is to enable users of financial statements to understand the effect of those arrangements on its financial position and to allow investors to better compare financial statements prepared under GAAP with financial statements prepared under International Financial Reporting Standards. As required, the Company added relevant disclosure in Note 16, “Derivatives and Hedging Activities.”
In February 2013, FASB issued ASU No. 2013-02, Comprehensive Income (Topic 220): Reporting of Amounts Reclassified out of Accumulated Other Comprehensive Income. This ASU states that the amendments do not change the current requirements for reporting net income or other comprehensive income in financial statements. The amendments do, however, require an entity to provide information about the amounts reclassified out of accumulated other comprehensive income by component. In addition, an entity is required to present, either on the face of the statement where net income is presented or in the notes, significant amounts reclassified out of accumulated other comprehensive income by the respective line items of net income, but only if the amount reclassified is required under U.S. GAAP to be reclassified to net income in its entirety in the same reporting period. For other amounts that are not required to be reclassified in their entirety to net income under U.S. GAAP, an entity is required to cross-reference to other disclosures required under U.S. GAAP that provide additional detail about those amounts. The amendments are effective prospectively for reporting periods beginning after December 15, 2012. In response to this ASU, the Company added a new footnote to disclose the amounts reclassified out of accumulated other comprehensive income and the effects on the line items of net income. See Note 15, “Comprehensive Income.”
In July 2013, FASB issued ASU 2013-10, Inclusion of the Fed Funds Effective Swap Rate (or Overnight Index Swap Rate) as a Benchmark Interest Rate for Hedge Accounting Purposes. This ASU amends ASC 815 to allow entities to use the Fed Funds Effective Swap Rate, in addition to U.S. Treasury rates and LIBOR, as a benchmark interest rate in accounting for fair value and cash flow hedges in the United States. This ASU also eliminates the provision from ASC 815-20-25-6 that prohibits the use of different benchmark rates for similar hedges except in rare and justifiable circumstances. This ASU is effective prospectively for qualifying new hedging relationship entered into on or after July 17, 2013, and for hedging relationship redesignated on or after that day. As of December 31, 2013, the Company did not have any fair value and cash flow hedges. The adoption of ASU No. 2013-10 did not have a material impact on the Company’s financial statements.
In July 2013, FASB issued ASU No. 2013-11, Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists. This ASU provides guidance on financial statement presentation of unrecognized tax benefits (“UTBs”) when a net operating loss (“NOL”) carryforward, a similar tax loss, or a tax credit carryforward exists. The FASB’s objective in issuing this ASU is to eliminate diversity in practice resulting from a lack of guidance on this topic in current U.S. GAAP. Under this ASU, an entity must present a UTB, or a portion of a UTB, in the financial statements as a reduction to a deferred tax asset (“DTA”) for an NOL carryforward, a similar tax loss, or a tax credit carryforward except when: (a) an NOL carryforward, a similar tax loss, or a tax credit carryforward is not available as of the reporting date under the governing tax law to settle taxes that would result from the disallowance of the tax position; or (b) the entity does not intend to use the DTA for this purpose (provided that the tax law permits a choice). If either of these conditions exists, an entity should present a UTB in the financial statements as a liability and should not net the UTB with a DTA. New recurring disclosures are not required because the ASU does not affect the recognition or measurement of uncertain tax positions under ASC 740. This amendment does not affect the amounts public entities disclose in the tabular reconciliation of the total amounts of UTBs because the tabular reconciliation presents the gross amount of UTBs. This ASU is effective for fiscal years beginning after December 15, 2013, and interim periods within those years. The amendments should be applied to all UTBs that exist as of the effective date. Entities may choose to apply the amendments retrospectively to each prior reporting period presented. As of December 31, 2013, the Company did not have a UTB. The Company will assess the applicability of this ASU after it become effective and as such has not determined the impact, if any, of this ASU.
In January 2014, the FASB issued ASU 2014-01, Accounting for Investments in Qualified Low-Income Housing Tax Credit (“LIHTC”) program. This ASU provides guidance on accounting for investments by a reporting entity in flow-through limited liability entities. Currently, investments in low-income housing are accounted for either by the effective yield, equity or cost method. This ASU allows for reporting entities to make a policy election on how to account for their investments. This ASU is applied retrospectively effective prospectively for all annual periods presented beginning after December 15, 2014; early adoption is permitted. The Company has not chosen to early adopt ASU No. 2014-01 and will assess the applicability of this ASU after it become effective and as such has not determined the impact, if any, of this ASU.
In January 2014, the FASB issued ASU 2014-04, Receivables—Troubled Debt Restructurings by Creditors. This ASU provides clarification on when an in substance repossession or foreclosure occurs resulting in the creditor derecognizing the loan and recognizing the collateral. Currently, there is no definition of in substance a repossession or foreclosure and physical possession in the accounting literature. This ASU is applied retrospectively or effective prospectively for all annual periods presented beginning after December 15, 2014; early adoption is permitted. The Company has not chosen to early adopt ASU No. 2014-04 and will assess the applicability of this ASU after it become effective and as such has not determined the impact, if any, of this ASU.

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2013
Business Combinations [Abstract]	'
Acquisitions	'
	Acquisitions
	Bancorp Rhode Island, Inc.
	On January 1, 2012 (the "BankRI Acquisition Date"), the Company acquired all the assets and liabilities of Bancorp Rhode Island, Inc., the bank holding company for BankRI. As part of the acquisition, Bancorp Rhode Island, Inc. was merged into the Company and no longer exists as a separate entity. BankRI, a commercial bank with 18 branches serving businesses and individuals in Rhode Island and nearby Massachusetts, continues to operate as a separate bank subsidiary of the Company.
	Total consideration paid in the acquisition was $205.8 million, which consisted of approximately 11 million shares of stock with a par value of approximately $0.1 million and a fair value of $92.8 million and $113.0 million in cash. Stock consideration was paid at the rate of 4.686 shares of Brookline Bancorp common stock per share of Bancorp Rhode Island, Inc. common stock. The assets acquired and the liabilities assumed in the acquisition were recorded by the Company at their estimated fair values as of the BankRI Acquisition Date.
	First Ipswich Bancorp
	On February 28, 2011 (the "First Ipswich Acquisition Date"), the Company acquired First Ipswich Bancorp, the bank holding company for First Ipswich. As part of the acquisition, First Ipswich Bancorp was effectively merged into the Company and no longer exists as a separate entity. First Ipswich, a commercial bank with six branches serving individuals and businesses on the north shore of eastern Massachusetts and in the Boston metropolitan area, continues to operate as a separate bank subsidiary of the Company.
	Total consideration paid in the First Ipswich acquisition consisted of $19.7 million in cash. The assets acquired and the liabilities assumed in the acquisition were recorded by the Company at their estimated fair values as of the First Ipswich Acquisition Date and the fair value of the assets acquired and liabilities assumed in the First Ipswich acquisition totaled $271.6 million and $252.0 million, respectively. No expenses related to the acquisition of First Ipswich were recorded in the years ended December 31, 2013 and December 31, 2012. Expenses relating to the acquisition of First Ipswich totaling $0.2 million were recorded in professional services expense in the year ended December 31, 2011.

Cash_and_ShortTerm_Investments

Cash and Short-Term Investments	12 Months Ended
	Dec. 31, 2013
Cash, Cash Equivalents, and Short-term Investments [Abstract]	'
Cash and Short-Term Investments	'
	Cash and Short-Term Investments
	Banks are required to maintain average reserve balances in a non-interest-bearing account with the Federal Reserve Bank based upon a percentage of certain of the Banks' deposits. As of December 31, 2013 and 2012, the average amount required to be held was $5.3 million and $3.7 million, respectively. Aggregate reserve balances included in cash and cash equivalents were $54.2 million and $41.7 million, respectively, at December 31, 2013 and 2012.
	Short-term investments are summarized as follows:
		At December 31,
		2013		2012
		(In Thousands)
	Money market funds	$	10	$	20
	Federal funds sold	55,347		38,636
		$	55,357	$	38,656
	Short-term investments are stated at cost which approximates market value. Money market funds are invested in mutual funds whose assets are comprised primarily of U.S. Treasury obligations, commercial paper and certificates of deposit with maturities of 90 days or less.

Investment_Securities

Investment Securities	12 Months Ended
	Dec. 31, 2013
Investments, Debt and Equity Securities [Abstract]	'
Investment Securities	'
	Investment Securities
	The following tables set forth investment securities available-for-sale and held-to-maturity at the dates indicated:
		At December 31, 2013
		Amortized		Gross		Gross			Estimated
		Cost		Unrealized		Unrealized			Fair Value
				Gains		Losses
		(In Thousands)
	Debt securities:
	GSEs	$	12,138	$	42	$	—		$	12,180
	GSE CMOs	254,331		86		10,773			243,644
	GSE MBSs	202,478		1,852		4,929			199,401
	Private-label CMOs	3,258		115		18			3,355
	SBA commercial loan asset-backed securities	245		—		2			243
	Auction-rate municipal obligations	1,900		—		125			1,775
	Municipal obligations	1,068		18		—			1,086
	Corporate debt obligations	27,751		506		33			28,224
	Trust preferred securities	1,461		—		251			1,210
	Total debt securities	504,630		2,619		16,131			491,118
	Marketable equity securities	1,259		61		10			1,310
	Total investment securities available-for-sale	$	505,889	$	2,680	$	16,141		$	492,428
	Investment securities held-to-maturity	$	500	$	—	$	—		$	500
		At December 31, 2012
		Amortized		Gross		Gross			Estimated
		Cost		Unrealized		Unrealized			Fair Value
				Gains		Losses
		(In Thousands)
	Debt securities:
	GSEs	$	69,504	$	305	$	—		$	69,809
	GSE CMOs	215,670		1,386		55			217,001
	GSE MBSs	165,996		3,704		52			169,648
	Private-label CMOs	6,719		147		—			6,866
	SBA commercial loan asset-backed securities	383		—		2			381
	Auction-rate municipal obligations	2,100		—		124			1,976
	Municipal obligations	1,058		43		—			1,101
	Corporate debt obligations	10,481		204		—			10,685
	Trust preferred securities and pools	2,786		136		403			2,519
	Total debt securities	474,697		5,925		636			479,986
	Marketable equity securities	1,249		88		—			1,337
	Total investment securities available-for-sale	$	475,946	$	6,013	$	636		$	481,323
	Investment securities held-to-maturity	$	500	$	2	$	—		$	502
	At December 31, 2013, the fair value of all securities available-for-sale was $492.4 million and carried a total of $13.5 million of net unrealized losses, compared to a fair value of $481.3 million and a net unrealized gain of $5.4 million at December 31, 2012. Of the $492.4 million in securities available-for-sale at December 31, 2013, $383.3 million, or 77.8%, of the portfolio, had gross unrealized losses of $16.1 million. This compares to $47.6 million, or 9.9%, of the portfolio with gross unrealized losses of $0.6 million at December 31, 2012. The shift from an unrealized gain position to an unrealized loss position in 2013 was primarily driven by rising interest rates.
	Investment Securities as Collateral
	At December 31, 2013 and 2012, respectively, $402.5 million and $309.7 million of investment securities available-for-sale were pledged as collateral for repurchase agreements; municipal deposits; treasury, tax and loan deposits; swap agreements; and FHLBB and FRB discount window borrowings. The Banks did not have any outstanding FRB borrowings at December 31, 2013 and 2012.
	Other-Than-Temporary Impairment ("OTTI")
	Investment securities at December 31, 2013 and 2012 that have been in a continuous unrealized loss position for less than twelve months or twelve months or longer are as follows:
		At December 31, 2013
		Less than				Twelve Months						Total
		Twelve Months				or Longer
		Estimated		Unrealized		Estimated			Unrealized			Estimated			Unrealized
		Fair Value		Losses		Fair Value			Losses			Fair Value			Losses
		(In Thousands)
	Debt securities:
	GSE CMOs	$	221,317	$	9,861	$	16,257		$	912		$	237,574		$	10,773
	GSE MBSs	121,836		3,746		13,516			1,183			135,352			4,929
	Private-label CMOs	639		18		—			—			639			18
	SBA commercial loan asset- backed securities	32		—		192			2			224			2
	Auction-rate municipal obligations	—		—		1,775			125			1,775			125
	Corporate debt obligations	5,988		33		—			—			5,988			33
	Trust preferred securities	—		—		1,210			251			1,210			251
	Temporarily impaired debt securities	349,812		13,658		32,950			2,473			382,762			16,131
	Marketable equity securities	501		10		—			—			501			10
	Total temporarily impaired securities	$	350,313	$	13,668	$	32,950		$	2,473		$	383,263		$	16,141
		At December 31, 2012
	Less than				Twelve Months						Total
	Twelve Months				or Longer
	Estimated		Unrealized		Estimated			Unrealized			Estimated			Unrealized
	Fair Value		Losses		Fair Value			Losses			Fair Value			Losses
	(In Thousands)
Debt securities:
GSE CMOs	$	23,910	$	55	$	—		$	—		$	23,910		$	55
GSE MBSs	19,186		47		235			5			19,421			52
Private-label CMOs	25		—		—			—			25			—
SBA commercial loan asset- backed securities	310		2		—			—			310			2
Auction-rate municipal obligations	—		—		1,976			124			1,976			124
Trust preferred securities and pools	—		—		1,931			403			1,931			403
Temporarily impaired debt securities	43,431		104		4,142			532			47,573			636
Marketable equity securities	—		—		—			—			—			—
Total temporarily impaired securities	$	43,431	$	104	$	4,142		$	532		$	47,573		$	636
The Company performs regular analysis on the available-for-sale securities portfolio to determine whether a decline in fair value indicates that an investment is OTTI. In making these OTTI determinations, management considers, among other factors, the length of time and extent to which the fair value has been less than amortized cost; projected future cash flows; credit subordination and the creditworthiness; capital adequacy and near-term prospects of the issuers.
Management also considers the Company's capital adequacy, interest-rate risk, liquidity and business plans in assessing whether it is more likely than not that the Company will sell or be required to sell the securities before recovery. If the Company determines that a decline in fair value is OTTI and that it is more likely than not that the Company will not sell or be required to sell the security before recovery of its amortized cost, the credit portion of the impairment loss is recognized in earnings and the noncredit portion is recognized in accumulated other comprehensive income. The credit portion of the OTTI impairment represents the difference between the amortized cost and the present value of the expected future cash flows of the security. If the Company determines that a decline in fair value is OTTI and it is more likely than not that it will sell or be required to sell the security before recovery of its amortized cost, the entire difference between the amortized cost and the fair value of the security will be recognized in earnings.
Debt Securities
The Company expects to recover its amortized cost basis on all debt securities in its available-for-sale and held-to-maturity portfolios. Furthermore, the Company does not intend to sell nor does it anticipate that it will be required to sell any of its securities in an unrealized loss position as of December 31, 2013, prior to the recovery of their amortized cost basis. The Company's ability and intent to hold these securities until recovery is supported by the Company's strong capital and liquidity positions as well as its historically low portfolio turnover.
U.S. Government-Sponsored Enterprises
The Company invests in securities issued by Government-sponsored enterprises ("GSEs"), including GSE debt securities, mortgage-backed securities ("MBSs"), and collateralized mortgage obligations ("CMOs"). GSE securities include obligations issued by the Federal National Mortgage Association ("FNMA"), the Federal Home Loan Mortgage Corporation ("FHLMC"), the Government National Mortgage Association ("GNMA"), the Federal Home Loan Banks and the Federal Farm Credit Bank. At December 31, 2013, only GNMA MBSs and CMOs, and Small Business Administration ("SBA") commercial loan asset-backed securities with an estimated fair value of $18.9 million were backed explicitly by the full faith and credit of the U.S. Government, compared to $10.0 million at December 31, 2012.
At December 31, 2013, the Company held GSE debentures with a total fair value of $12.2 million and a net unrealized gain of $42.0 thousand. At December 31, 2012, the Company held GSE debentures with a total fair value of $69.8 million and a net unrealized gain of $0.3 million. At December 31, 2013, none of the five securities in this portfolio were in unrealized loss positions. At December 31, 2012, none of the twenty-eight securities in this portfolio were in unrealized loss positions. All securities are performing and backed by the implicit(FHLB/FNMA/FHLMC) or explicit(GNMA/SBA) guarantee of the U.S Government.
At December 31, 2013, the Company held SBA securities with a total fair value of $0.2 million and a net unrealized loss of $2.0 thousand. At December 31, 2012, the Company held SBA securities with a total fair value of $0.4 million and a net unrealized loss of less than $2.0 thousand. At December 31, 2013, seven of the nine securities in this portfolio were in unrealized loss positions. At December 31, 2012, eight of the eleven securities in this portfolio were in unrealized loss positions. All securities are performing and backed by the explicit (SBA) guarantee of the U.S Government.
As of December 31, 2013, the Company held GSE mortgage-related securities with a total fair value of $443.0 million and a net unrealized loss of $13.8 million. This compares to a total fair value of $386.6 million and a net unrealized gain of $5.0 million at December 31, 2012. At December 31, 2013, 86 of the 232 securities in this portfolio were in unrealized loss positions. At December 31, 2012, 32 of the 224 securities in this portfolio were in unrealized loss positions. All securities are performing and backed by the implicit(FHLB/FNMA/FHLMC) or explicit(GNMA) guarantee of the U.S Government. During the years ended December 31, 2013 and 2012, the Company purchased a total of $149.5 million and $326.1 million, respectively, in GSE CMOs and GSE MBSs to reinvest cash from matured securities.
Private-Label CMOs
At December 31, 2013, the Company held private-issuer CMO-related securities with a total fair value of $3.4 million and a net unrealized gain of $0.1 million. At December 31, 2012, the Company held private-issuer CMO-related securities with a total fair value of $6.9 million and a net unrealized gain of $0.1 million. At December 31, 2013, two of the eleven securities in this portfolio were in unrealized loss positions. At December 31, 2012, one of the eleven securities in this portfolio were in unrealized loss positions. All securities are performing and while one security was downgraded in 2013, the security is in an unrealized gain position and the underlying credit metrics have not deteriorated in 2013.
Auction-Rate Municipal Obligations and Municipal Obligations
The auction-rate obligations owned by the Company were rated "AAA" at the time of acquisition due, in part, to the guarantee of third-party insurers who would have to pay the obligations if the issuers failed to pay the obligations when they become due. During the financial crisis, certain third-party insurers experienced financial difficulties and were not able to meet their contractual obligations. As a result, auctions failed to attract a sufficient number of investors and created a liquidity problem for those investors who were relying on the obligations to be redeemed at auction. Since then, there has not been an active market for auction-rate municipal obligations.
Based on an evaluation of market factors, the estimated fair value of the auction-rate municipal obligations owned by the Company at December 31, 2013 was $1.8 million, with a corresponding net unrealized loss of $0.1 million. This compares to $2.0 million with a corresponding net unrealized loss of $0.1 million at December 31, 2012. At December 31, 2013, all of the remaining securities in this portfolio were in unrealized loss positions. At December 31, 2012, all three of the securities in this portfolio were in unrealized loss positions. Full collection of the obligations is expected because the financial condition of the issuers is sound, none of the issuers has defaulted on scheduled payments, the obligations are rated investment grade and the Company has the ability and intent to hold the obligations for a period of time to recover the amortized cost.
The Company owns municipal obligations with an estimated fair value of $1.1 million which approximates amortized cost at December 31, 2013. This compares to a total fair value of $1.1 million which also approximates amortized cost at December 31, 2012. At both December 31, 2013 and 2012, none of the two securities in this portfolio were in unrealized loss positions. Full collection of the obligations is expected because the financial condition of the issuers is sound, none of the issuers has defaulted on scheduled payments, the obligations are rated investment grade and the Company has the ability and intent to hold the obligations for a period of time to recover the amortized cost.
Corporate Obligations
From time to time, the Company will invest in high-quality corporate obligations to provide portfolio diversification and improve the overall yield on the portfolio. The Company owned eleven corporate obligation securities with a total fair value of $28.2 million and total net unrealized gains of $0.5 million as of December 31, 2013. This compares to eight corporate obligation securities with a total fair value of $10.7 million and total net unrealized gains of $0.2 million at December 31, 2012. At both December 31, 2013 and 2012, all but one of the securities are investment grade and this security is currently in an unrealized gain position. At December 31, 2013, two of the eleven securities in this portfolio are in unrealized loss positions. At December 31, 2012, none of the eight securities in this portfolio were in unrealized loss positions. Full collection of the obligations is expected because the financial condition of the issuers is sound, none of the issuers has defaulted on scheduled payments, the obligations are rated investment grade and the Company has the ability and intent to hold the obligations for a period of time to recover the unrealized losses. During the year ended December 31, 2013, the Company purchased $21.7 million in corporate obligations. The Company did not purchase any corporate obligations in the same period in 2012.
Trust Preferred Securities and PreTSLs
Trust preferred securities represent subordinated debt issued by financial institutions. These securities are sometimes pooled and sold to investors through structured vehicles known as trust preferred pools (“PreTSLs”). When issued, PreTSLs are divided into tranches or segments that establish priority rights to cash flows from the underlying trust preferred securities. At December 31, 2013, the Company owned two trust preferred securities and no PreTSL pools with a total fair value of $1.2 million and a total net unrealized loss of $0.3 million. This compares to three trust preferred securities and two PreTSL pools with a total fair value of $2.5 million and a total net unrealized loss of $0.3 million at December 31, 2012. At December 31, 2013, all of the securities in this portfolio were in unrealized loss positions, which represents 17.2% of the amortized cost of the securities. At December 31, 2012, three of the five securities in the Company’s portfolio were in unrealized loss positions, which represents 14.5% of the amortized cost of the securities.
During the year ended December 31, 2013, the Company sold two PreTSL pooled securities for a net gain of $0.4 million. At the time of sale, the proposed "Volcker Rule" of the Dodd-Frank Wall Street Reform and Consumer Protection Act, restricted banks from owning PreTSL pooled securities. The Company had the ability and intent to hold both securities to maturity prior to the new proposed regulations based on the amortized cost of the securities held at that time versus market indications. The Company identified that these securities were subject to the "Volcker Rule” and decided to sell the securities while a market existed. After regulatory review in January 2014, the "Volcker Rule" was revised and banks of less than $10 billion in size were grandfathered to hold these securities in their portfolios.
Marketable Equity Securities
At both December 31, 2013 and 2012, the Company owned marketable equity securities with a fair value of $1.3 million, including net unrealized gains of $0.1 million. At December 31, 2013, one of the four securities in this portfolio was in an unrealized loss position, which represents 0.8% of the amortized cost of the securities. At December 31, 2012, none of the four securities in this portfolio were in an unrealized loss position.
Securities Held-to-Maturity
The Company purchased $0.5 million of State of Israel bonds in 2011 with a carrying value of $0.5 million and a fair value of $0.5 million. This security matures in March, 2014 and carries an interest rate payable of LIBOR plus 0.125%.
Portfolio Maturities
The maturities of the investments in debt securities available-for-sale at the dates indicated are as follows:
	At December 31,
	2013						2012
	Amortized		Estimated		Weighted		Amortized			Estimated			Weighted
	Cost		Fair Value		Average		Cost			Fair Value			Average
					Rate								Rate
	(Dollars in Thousands)
Investment securities available-for-sale:
Within 1 year	$	13,012	$	13,062	0.82	%	$	59,396		$	59,736		1.2	%
After 1 year through 5 years	40,204		41,187		2.9	%	25,249			25,579			1.61	%
After 5 years through 10 years	66,447		67,075		2.23	%	50,283			52,557			3.29	%
Over 10 years	384,967		369,794		1.9	%	339,769			342,114			1.93	%
	$	504,630	$	491,118	2	%	$	474,697		$	479,986		1.97	%
Actual maturities of GSE debt securities may differ from those presented above since certain obligations provide the issuer the right to call or prepay the obligation prior to scheduled maturity without penalty. At December 31, 2013, there were no remaining callable GSE securities in the investment portfolio. At December 31, 2013, issuers of other debt securities with an estimated fair value of approximately $3.7 million had the right to call or prepay the obligations, the scheduled maturities of which were $0.7 million less than one year, and $3.0 million after ten years. At December 31, 2012, issuers of all debt securities with an estimated fair value of approximately $8.9 million had the right to call or prepay the obligations, the scheduled maturities of which were $4.8 million after one year through five years, $0.2 million after five years through ten years, and $3.9 million after ten years. MBSs and CMOs are included above based on their contractual maturities; the remaining lives, however, are expected to be shorter due to anticipated payments.
Security Sales
Sales of investment securities are summarized as follows:
	Year Ended December 31,
	2013		2012		2011
	(In Thousands)
Sales of debt securities	$	1,210	$	166,201	$	—
Sales of marketable equity securities	—		—		124
Gross gains from sales	626		1,093		80
Gross losses from sales	229		167		—
Security transactions are recorded on the trade date. When securities are sold, the adjusted cost of the specific security sold is used to compute the gain or loss on the sale.

Restricted_Equity_Securities

Restricted Equity Securities	12 Months Ended
	Dec. 31, 2013
Restricted Investments Note [Abstract]	'
Restricted Equity Securities	'
	Restricted Equity Securities
	Investments in the restricted equity securities of various entities are as follows:
		At December 31,
		2013		2012
		(In Thousands)
	FHLBB stock	$	50,081	$	52,188
	Federal Reserve Bank of Boston stock	16,003		15,998
	Other restricted equity securities	475		475
		$	66,559	$	68,661
	At December 31, 2013 and 2012, FHLBB stock is recorded at its carrying value, which is equal to cost and which management believes approximates its fair value. The FHLBB was classified as "adequately capitalized" by its regulator at December 31, 2013, effected the repurchase of $300 million of capital stock during 2013 and paid a stable modest dividend of 38bps during 2013. At December 31, 2013, the Company's investment in FHLBB stock exceeded its required investment which provides for additional borrowing capacity.
	The FHLBB has announced its intent to declare modest dividends throughout 2014, but cautioned that should adverse events occur, such as a negative trend in credit losses on the FHLBB's private-label MBSs or its mortgage portfolio, a meaningful decline in income or regulatory disapproval, dividends could again be suspended.
	The Company increased its investment in the stock of the Federal Reserve Bank of Boston in 2012, consistent with the conversion of Brookline Bank and BankRI to state-chartered banks supervised by the Federal Reserve Bank of Boston. At December 31, 2013 and 2012, Federal Reserve Bank of Boston stock is recorded at its carrying value, which is equal to cost and which management believes approximates its fair value.

Loans_and_Leases

Loans and Leases	12 Months Ended
	Dec. 31, 2013
Loans and Leases Receivable Disclosure [Abstract]	'
Loans and Leases	'
	Loans and Leases
	The following tables present loan and lease balances and weighted average coupon rates for the originated and acquired loan and lease portfolios at the dates indicated:
		At December 31, 2013
		Originated						Acquired						Total
		Balance			Weighted			Balance				Weighted		Balance		Weighted
					Average							Average				Average
					Coupon							Coupon				Coupon
		(Dollars In Thousands)
	Commercial real estate loans:
	Commercial real estate	$	1,111,750		4.34	%		$	350,235			4.42	%	$	1,461,985	4.36	%
	Multi-family mortgage	554,555			4.19	%		73,378				4.63	%	627,933		4.24	%
	Construction	102,927			3.81	%		10,778				4.37	%	113,705		3.87	%
	Total commercial real estate loans	1,769,232			4.26	%		434,391				4.46	%	2,203,623		4.3	%
	Commercial loans and leases:
	Commercial	297,684			3.68	%		110,108				4.54	%	407,792		3.91	%
	Equipment financing	485,330			7.14	%		27,694				6.6	%	513,024		7.11	%
	Condominium association	44,794			4.74	%		—				—		44,794		4.74	%
	Total commercial loans and leases	827,808			5.77	%		137,802				4.95	%	965,610		5.65	%
	Indirect automobile loans	400,531			4.98	%		—				—		400,531		4.98	%
	Consumer loans:
	Residential mortgage	411,554			3.65	%		116,631				3.93	%	528,185		3.71	%
	Home equity	132,396			3.39	%		125,065				3.88	%	257,461		3.63	%
	Other consumer	5,532			5.98	%		1,523				14.89	%	7,055		7.9	%
	Total consumer loans	549,482			3.61	%		243,219				3.98	%	792,701		3.72	%
	Total loans and leases	$	3,547,053		4.59	%		$	815,412			4.38	%	$	4,362,465	4.55	%
		At December 31, 2012
		Originated						Acquired						Total
		Balance			Weighted			Balance				Weighted		Balance		Weighted
					Average							Average				Average
					Coupon							Coupon				Coupon
		(Dollars In Thousands)
	Commercial real estate loans:
	Commercial real estate	$	871,552		4.62	%		$	429,681			4.69	%	$	1,301,233	4.64	%
	Multi-family mortgage	506,017			4.5	%		100,516				4.99	%	606,533		4.58	%
	Construction	80,913			4.2	%		17,284				4.73	%	98,197		4.29	%
	Total commercial real estate loans	1,458,482			4.56	%		547,481				4.75	%	2,005,963		4.61	%
	Commercial loans and leases:
	Commercial	230,892			3.89	%		151,385				4.72	%	382,277		4.22	%
	Equipment financing	366,297			7.69	%		54,694				6.91	%	420,991		7.59	%
	Condominium association	44,187			5.02	%		—				—		44,187		5.02	%
	Total commercial loans and leases	641,376			6.14	%		206,079				5.3	%	847,455		5.93	%
	Indirect automobile loans	542,344			5.31	%		—				—		542,344		5.31	%
	Consumer loans:
	Residential mortgage	368,095			3.87	%		143,014				4.18	%	511,109		3.93	%
	Home equity	99,683			3.45	%		161,879				4.07	%	261,562		3.83	%
	Other consumer	6,122			5.35	%		1,157				12.97	%	7,279		6.56	%
	Total consumer loans	473,900			3.78	%		306,050				4.15	%	779,950		3.92	%
	Total loans and leases	$	3,116,102		4.89	%		$	1,059,610			4.67	%	$	4,175,712	4.83	%
	The Company's lending is primarily in eastern Massachusetts, southern New Hampshire and Rhode Island, with the exception of equipment financing, 38.2% of which is in the greater New York/New Jersey metropolitan area and 61.8% of which is in other areas in the United States of America.
	For the year ended December 31, 2012, the Company sold $19.6 million of loans and leases, which resulted in a $1.9 million gain on sale recorded in non-interest income.
	Accretable Yield for the Acquired Loan Portfolio
	The following table summarizes activity in the accretable yield for the acquired loan portfolio for the periods indicated:
		Year Ended December 31,
		2013			2012				2011
		(In Thousands)
	Balance at beginning of year	$	57,812		$	(1,369	)		$	—
	Acquisitions	—			81,503				(2,504		)
	Reclassification from nonaccretable difference for loans with improved cash flows	8,477			1,550				—
	Accretion	(20,500		)	(23,872		)		1,135
	Balance at end of year	$	45,789		$	57,812			$	(1,369	)
	Subsequent to acquisition, on a quarterly basis, Management reforecasts the expected cash flows for acquired ASC 310-30 loans, taking into account prepayment speeds, probability of default and loss given defaults. Management then compares this reforecast to the original estimates to evaluate the need for a loan loss provision and/or prospective yield adjustments. During the years ended December 31, 2013 and 2012, accretable yield adjustments totaling $8.5 million and $1.6 million, respectively were made for certain loan pools. These accretable yield adjustments, which are subject to continued re-assessment, will be recognized over the remaining lives of those pools. No provision for loans losses were recorded in 2012; however, a provision of $0.9 million was recorded during the year ended December 31, 2013 as a result of our reforecasts primarily due to decreases in expected cash flows.
	The aggregate remaining nonaccretable difference (representing both principal and interest) applicable to acquired loans totaled $4.5 million and $13.0 million at December 31, 2013 and 2012, respectively.
	Related Party Loans
The Banks' authority to extend credit to their respective directors and executive officers, as well as to entities controlled by such persons, is currently governed by the requirements of the Sarbanes-Oxley Act and Regulation O of the FRB. Among other things, these provisions require that extensions of credit to insiders (1) be made on terms that are substantially the same as, and follow credit underwriting procedures that are not less stringent than, those prevailing for comparable transactions with unaffiliated persons and that do not involve more than the normal risk of repayment or present other unfavorable features; and (2) not exceed certain limitations on the amount of credit extended to such persons, individually and in the aggregate, which limits are based, in part, on the amount of the Banks' capital. In addition, the extensions of credit to insiders must be approved by each Bank's Board of Directors.
The following table summarizes the change in the total amounts of loans and advances, to directors, executive officers and their affiliates for the periods indicated. All loans were performing at December 31, 2013.
	Year Ended December 31,
	2013			2012				2011
	(In Thousands)
Balance at beginning of year	$	4,083		$	16,428			$	16,399
Acquired loans	—			2,848				222
New loans granted during the year	365			314				288
Advances on lines of credit	1,370			109				—
Repayments	(1,035		)	(15,281		)		(481		)
Loan no longer classified as an insider loan	—			(335		)		—
Loans reclassified as insider loans	11,327			—				—
Balance at end of year	$	16,110		$	4,083			$	16,428
Unfunded commitments on extensions of credit to insiders totaled $11.7 million and $6.9 million at December 31, 2013 and 2012, respectively.
Loans and Leases Pledged as Collateral
At December 31, 2013 and 2012, there were $1.2 billion and $1.5 billion, respectively, of loans and leases pledged as collateral for repurchase agreements; municipal deposits; treasury, tax and loan deposits; swap agreements; and FHLBB and FRB discount window borrowings.

Allowance_for_Loan_and_Lease_L

Allowance for Loan and Lease Losses	12 Months Ended
	Dec. 31, 2013
Loans and Leases Receivable, Allowance [Abstract]	'
Allowance for Loan and Lease Losses	'
	Allowance for Loan and Lease Losses
	The following tables present the changes in the allowance for loan and lease losses and the recorded investment in loans and leases by portfolio segment for the periods indicated:
		Year Ended December 31, 2013
		Commercial				Commercial				Indirect				Consumer				Unallocated				Total
		Real Estate								Automobile
		(In Thousands)
	Balance at December 31, 2012	$	20,018			$	10,655			$	5,304			$	2,545			$	2,630			$	41,152
	Charge-offs	(88		)		(2,077		)		(1,714		)		(909		)		—				(4,788		)
	Recoveries	13				657				501				263				—				1,434
	Provision (credit) for loan and lease losses	3,079				5,985				(167		)		1,476				302				10,675
	Balance at December 31, 2013	$	23,022			$	15,220			$	3,924			$	3,375			$	2,932			$	48,473
		Year Ended December 31, 2012
		Commercial				Commercial				Indirect				Consumer				Unallocated				Total
		Real Estate								Automobile
		(In Thousands)
	Balance at December 31, 2011	$	15,477			$	5,997			$	5,604			$	1,577			$	3,048			$	31,703
	Charge-offs	—				(5,347		)		(2,153		)		(592		)		—				(8,092		)
	Recoveries	118				417				969				26				—				1,530
	Provision (credit) for loan and lease losses	4,423				9,588				884				1,534				(418		)		16,011
	Balance at December 31, 2012	$	20,018			$	10,655			$	5,304			$	2,545			$	2,630			$	41,152
		Year Ended December 31, 2011
		Commercial				Commercial				Indirect				Consumer				Unallocated				Total
		Real Estate								Automobile
		(In Thousands)
	Balance at December 31, 2010	$	12,398			$	5,293			$	6,952			$	1,638			$	3,414			$	29,695
	Charge-offs	(30		)		(773		)		(2,076		)		(12		)		—				(2,891		)
	Recoveries	—				330				605				8				—				943
	Provision (credit) for loan and lease losses	3,109				1,147				123				(57		)		(366		)		3,956
	Balance at December 31, 2011	$	15,477			$	5,997			$	5,604			$	1,577			$	3,048			$	31,703
	The liability for unfunded credit commitments, which is included in other liabilities, was $1.0 million, $0.7 million and$0.8 million at December 31, 2013, 2012 and 2011, respectively. The changes in the liability for unfunded credit commitments reflect changes in the estimate of loss exposure associated with certain unfunded credit commitments. No credit commitments were charged off against the liability account in the years ended December 31, 2013, 2012 and 2011.
	Provision for Credit Losses
	The provisions for credit losses are set forth below for the periods indicated:
		Originated												Acquired												Total
		Year Ended December 31,												Year Ended December 31,												Year Ended December 31,
		2013				2012				2011				2013				2012				2011				2013				2012			2011
		(In Thousands)
	Provision for loan and lease losses:
	Commercial real estate	$	2,563			$	4,348			$	3,109			$	516			$	75			$	—			$	3,079			$	4,423		$	3,109
	Commercial	4,917				9,513				1,147				1,068				75				—				5,985				9,588			1,147
	Indirect automobile	(167		)		884				123				—				—				—				(167		)		884			123
	Consumer	286				1,534				(57		)		1,190				—				—				1,476				1,534			(57		)
	Unallocated	302				(418		)		(366		)		—				—				—				302				(418		)	(366		)
	Total provision for loan and lease losses	7,901				15,861				3,956				2,774				150				—				10,675				16,011			3,956
	Unfunded credit commitments	254				(123		)		(325		)		—				—				—				254				(123		)	(325		)
	Total provision for credit losses	$	8,155			$	15,738			$	3,631			$	2,774			$	150			$	—			$	10,929			$	15,888		$	3,631
	Allowance for Loan and Lease Losses Methodology
	Management has established a methodology to determine the adequacy of the allowance for loan and lease losses that assesses the risks and losses inherent in the loan and lease portfolio. For purposes of determining the allowance for loan and lease losses, the Company has segmented certain loans and leases in the portfolio by product type into the following pools: (1) commercial real estate loans, (2) commercial loans and leases, (3) indirect automobile loans and (4) consumer loans. Portfolio segments are further disaggregated into classes based on the associated risks within the segments. Commercial real estate loans are divided into three classes: commercial real estate mortgage loans, multi-family mortgage loans and construction loans. Commercial loans and leases are divided into three classes: commercial loans, equipment financing, and loans to condominium associations. The indirect automobile loan segment is not divided into classes. Consumer loans are divided into three classes: residential mortgage loans, home equity loans and other consumer loans. For each class of loan, management makes significant judgments in selecting the estimation method that fits the credit characteristics of its class and portfolio segment as set forth below. (Refer to Note 1, "Basis of Presentation," in the consolidated financial statements for more information on the Company's allowance of loan and lease losses methodology.)
	General Allowance
	The general allowance for loan and lease losses was $44.1 million at December 31, 2013, compared to $36.8 million at December 31, 2012. The general portion of the allowance for loan and lease losses increased by $7.3 million during the year ended December 31, 2013, as a result of growth in the commercial real estate and equipment financing portfolios partially offset by the decrease in the indirect auto portfolios.
	Specific Allowance
	The specific allowance for loan and lease losses was $1.5 million at December 31, 2013, compared to $1.7 million at December 31, 2012. The specific allowance decreased by $0.2 million during the year ended December 31, 2013, largely as a result of a large commercial real estate loan payoff, offset by an increase in specific reserves on the equipment financing portfolio.
	Unallocated Allowance
	The unallocated allowance for loan and lease losses was $2.9 million at December 31, 2013, compared to $2.6 million at December 31, 2012. The unallocated portion of the allowance for loan and lease losses increased by $0.3 million during the year ended December 31, 2013, largely as a result of a change in the mix of the loan portfolio and loan growth.
	Credit Quality Assessment
	At the time of loan origination, a rating is assigned based on the financial strength of the borrower and the value of assets pledged as collateral. The Company continually monitors the asset quality of the loan portfolio using all available information. The officer responsible for handling each loan is required to initiate changes to risk ratings when changes in facts and circumstances occur that warrant an upgrade or downgrade in a loan rating. Based on this information, loans demonstrating certain payment issues or other weaknesses may be categorized as delinquent, impaired, nonperforming and/or put on nonaccrual status. Additionally, in the course of resolving such loans, the Company may choose to restructure the contractual terms of certain loans to match the borrower's ability to repay the loan based on their current financial condition. If a restructured loan meets certain criteria, it may be categorized as a troubled debt restructuring.
	The Company reviews numerous credit quality indicators when assessing the risk in its loan portfolio. For the commercial real estate mortgage, multi-family mortgage, construction, commercial, equipment financing, condominium association and other consumer loan and lease classes, the Company utilizes an eight-grade loan rating system, which assigns a risk rating to each borrower based on a number of quantitative and qualitative factors associated with a loan transaction. Factors considered include industry and market conditions; position within the industry; earnings trends; operating cash flow; asset/liability values; debt capacity; guarantor strength; management and controls; financial reporting; collateral; and other considerations. In addition, the Company's independent loan review group evaluates the credit quality and related risk ratings of the commercial real estate and commercial loan portfolios. The results of these reviews are reported to the Audit Committee of the Board of Directors. For the indirect automobile portfolio, the Company primarily relies on payment status for monitoring credit risk while for residential mortgage and home equity portfolios loan-to-value ratios are used as the primary credit quality indicator.
	The ratings categories used for assessing credit risk in the commercial real estate mortgage, multi-family mortgage, construction, commercial, equipment financing, condominium association and other consumer loan and lease classes are defined as follows:
	1 -4 Rating—Pass
	Loan rating grades "1" through "4" are classified as "Pass," which indicates borrowers are performing in accordance with the terms of the loan and are less likely to result in loss due to the capacity of the borrower to pay and the adequacy of the value of assets pledged as collateral.
	5 Rating—Other Asset Especially Mentioned ("OAEM")
	Borrowers exhibit potential credit weaknesses or downward trends deserving management's attention. If not checked or corrected, these trends will weaken the Company's asset and position. While potentially weak, currently these borrowers are marginally acceptable; no loss of principal or interest is envisioned.
	6 Rating—Substandard
	Borrowers exhibit well defined weaknesses that jeopardize the orderly liquidation of debt. Substandard loans may be inadequately protected by the current net worth and paying capacity of the obligors or by the collateral pledged, if any. Normal repayment from the borrower is in jeopardy. Although no loss of principal is envisioned, there is a distinct possibility that a partial loss of interest and/or principal will occur if the deficiencies are not corrected. Collateral coverage may be inadequate to cover the principal obligation.
7 Rating—Doubtful
Borrowers exhibit well-defined weaknesses that jeopardize the orderly liquidation of debt with the added provision that the weaknesses make collection of the debt in full, on the basis of currently existing facts, conditions, and values, highly questionable and improbable. Serious problems exist to the point where partial loss of principal is likely.
8 Rating—Definite Loss
Borrowers deemed incapable of repayment. Loans to such borrowers are considered uncollectible and of such little value that continuation as active assets of the Company is not warranted.
Assets rated as "OAEM," "substandard" or "doubtful" based on criteria established under banking regulations are collectively referred to as "criticized" assets.
Credit Quality Information
The following tables present the recorded investment in total loans in each class (unpaid balance of loans and leases outstanding excluding deferred loan origination costs) at December 31, 2013 by credit quality indicator.
	At December 31, 2013
	Commercial				Multi-				Construction				Commercial				Equipment				Condominium				Other
	Real Estate				Family												Financing				Association				Consumer
	Mortgage				Mortgage
	(In Thousands)
Originated:
Loan rating:
Pass	$	1,099,108			$	554,183			$	102,927			$	295,057			$	479,811			$	44,793			$	5,528
OAEM	11,555				372				—				49				625				—				—
Substandard	1,087				—				—				1,078				4,817				1				4
Doubtful	—				—				—				1,500				77				—				—
Total originated	1,111,750				554,555				102,927				297,684				485,330				44,794				5,532
Acquired:
Loan rating:
Pass	332,145				69,310				10,090				96,779				27,535				—				1,509
OAEM	7,556				463				688				4,617				61				—				—
Substandard	8,645				3,605				—				8,518				98				—				14
Doubtful	1,889				—				—				194				—				—				—
Total acquired	350,235				73,378				10,778				110,108				27,694				—				1,523
Total loans by class	$	1,461,985			$	627,933			$	113,705			$	407,792			$	513,024			$	44,794			$	7,055
	At December 31, 2013
	Indirect Automobile
	Dollars In Thousands				Percent
Originated:
Credit score:
Over 700	$	332,140			82.9	%
661-700	54,038				13.5	%
660 and below	12,793				3.2	%
Data not available	1,560				0.4	%
	$	400,531			100	%
		At December 31, 2013
		Residential Mortgage							Home Equity
		Dollars In Thousands				Percent			Dollars In Thousands				Percent
Originated:
Loan-to-value ratio:
Less than 50%		$	94,500			17.9	%		$	75,372			29.3	%
50% - 69%		149,969				28.4	%		31,504				12.2	%
70% - 79%		139,960				26.5	%		21,161				8.2	%
80% and over		22,772				4.3	%		3,240				1.3	%
Data not available		4,353				0.8	%		1,119				0.4	%
Total originated		411,554				77.9	%		132,396				51.4	%
Acquired:
Loan-to-value ratio:
Less than 50%		$	23,101			4.4	%		$	84,272			32.7	%
50%—69%		39,298				7.4	%		25,964				10.1	%
70%—79%		31,932				6	%		13,390				5.2	%
80% and over		19,870				3.8	%		1,208				0.5	%
Data not available		2,430				0.5	%		231				0.1	%
Total acquired		116,631				22.1	%		125,065				48.6	%
Total loans		$	528,185			100	%		$	257,461			100	%
The following tables present the recorded investment in loans in each class (unpaid balance of loans and leases outstanding excluding deferred loan origination costs) at December 31, 2012 by credit quality indicator.
	At December 31, 2012
	Commercial				Multi-				Construction				Commercial				Equipment				Condominium				Other
	Real Estate				Family												Financing				Association				Consumer
	Mortgage				Mortgage
	(In Thousands)
Originated:
Loan rating:
Pass	$	863,901			$	504,883			$	80,913			$	227,201			$	359,064			$	44,179			$	6,093
OAEM	5,686				146				—				1,196				2,979				—				—
Substandard	1,965				988				—				502				4,213				8				29
Doubtful	—				—				—				1,993				41				—				—
Total originated	871,552				506,017				80,913				230,892				366,297				44,187				6,122
Acquired:
Loan rating:
Pass	409,725				93,058				17,186				140,589				54,175				—				1,157
OAEM	2,740				2,439				—				1,344				286				—				—
Substandard	17,216				5,019				98				8,635				233				—				—
Doubtful	—				—				—				817				—				—				—
Total acquired	429,681				100,516				17,284				151,385				54,694				—				1,157
Total loans by class	$	1,301,233			$	606,533			$	98,197			$	382,277			$	420,991			$	44,187			$	7,279
	At December 31, 2012
	Indirect Automobile
	Dollars In Thousands				Percent
Originated:
Credit score:
Over 700	$	454,056			83.7	%
661-700	69,319				12.8	%
660 and below	16,934				3.1	%
Data not available	2,035				0.4	%
	$	542,344			100	%
		At December 31, 2012
		Residential Mortgage							Home Equity
		Dollars In Thousands				Percent			Dollars In Thousands				Percent
Originated:
Loan-to-value ratio:
Less than 50%		$	86,659			17	%		$	50,398			19.3	%
50%—69%		142,172				27.8	%		25,284				9.7	%
70%—79%		111,234				21.8	%		16,523				6.3	%
80% and over		27,858				5.4	%		6,042				2.3	%
Data not available		172				—	%		1,436				0.5	%
		368,095				72	%		99,683				38.1	%
Acquired:
Loan-to-value ratio:
Less than 50%		23,398				4.6	%		28,401				10.9	%
50%—69%		42,214				8.2	%		39,385				15.1	%
70%—79%		42,748				8.4	%		33,044				12.6	%
80% and over		31,614				6.2	%		34,267				13.1	%
Data not available		3,040				0.6	%		26,782				10.2	%
		143,014				28	%		161,879				61.9	%
Total loans		$	511,109			100	%		$	261,562			100	%
Age Analysis of Past Due Loans and Leases
The following tables present an age analysis of the recorded investment in total loans and leases (unpaid balance of loans and leases outstanding excluding deferred loan origination costs) at December 31, 2013 and 2012.
	At December 31, 2013
	Past Due																								Loans and
																									Leases Past
																									Due Greater
																									Than 90 Days
	31-60				61-90				Greater				Total				Current				Total Loans				and Accruing				Nonaccrual
	Days				Days				Than												and Leases								Loans and
									90 Days																				Leases
	(In Thousands)
Originated:
Commercial real estate loans:
Commercial real estate mortgage	$	4,896			$	1,393			$	169			$	6,458			$	1,105,292			$	1,111,750			$	—			$	169
Multi-family mortgage	14,400				—				—				14,400				540,155				554,555				—				—
Construction	—				—				—				—				102,927				102,927				—				—
Total commercial real estate loans	19,296				1,393				169				20,858				1,748,374				1,769,232				—				169
Commercial loans and leases:
Commercial	2,288				75				842				3,205				294,479				297,684				—				1,551
Equipment financing	867				1,558				2,031				4,456				480,874				485,330				—				4,086
Condominium association	—				—				—				—				44,794				44,794				—				1
Total commercial loans and leases	3,155				1,633				2,873				7,661				820,147				827,808				—				5,638
Indirect automobile	5,407				857				229				6,493				394,038				400,531				10				259
Consumer loans:
Residential mortgage	201				—				415				616				410,938				411,554				—				1,713
Home equity	218				—				—				218				132,178				132,396				—				462
Other consumer	11				1				4				16				5,516				5,532				—				4
Total consumer loans	430				1				419				850				548,632				549,482				—				2,179
Total originated loans and leases	$	28,288			$	3,884			$	3,690			$	35,862			$	3,511,191			$	3,547,053			$	10			$	8,245
	At December 31, 2013
	Past Due																								Loans and
																									Leases Past
																									Due Greater
																									Than 90 Days
	31-60				61-90				Greater				Total				Current				Total Loans				and Accruing				Nonaccrual
	Days				Days				Than												and Leases								Loans and
									90 Days																				Leases
	(In Thousands)
Acquired:
Commercial real estate loans:
Commercial real estate mortgage	$	1,221			$	87			$	4,887			$	6,195			$	344,040			$	350,235			$	3,958			$	929
Multi-family mortgage	327				—				1,052				1,379				71,999				73,378				1,052				—
Construction	—				409				—				409				10,369				10,778				—				—
Total commercial real estate loans	1,548				496				5,939				7,983				426,408				434,391				5,010				929
Commercial loans and leases:
Commercial	2,707				121				1,931				4,759				105,349				110,108				1,235				4,597
Equipment financing	46				41				73				160				27,534				27,694				73				29
Total commercial loans and leases	2,753				162				2,004				4,919				132,883				137,802				1,308				4,626
Consumer loans:
Residential mortgage	271				777				5,329				6,377				110,254				116,631				4,468				1,162
Home equity	1,259				552				895				2,706				122,359				125,065				117				1,525
Other consumer	6				11				4				21				1,502				1,523				—				14
Total consumer loans	1,536				1,340				6,228				9,104				234,115				243,219				4,585				2,701
Total acquired loans and leases	$	5,837			$	1,998			$	14,171			$	22,006			$	793,406			$	815,412			$	10,903			$	8,256
	At December 31, 2012
	Past Due																								Loans and
																									Leases Past
																									Due Greater
																									Than 90 Days
	31-60				61-90				Greater				Total				Current				Total Loans				and Accruing				Nonaccrual
	Days				Days				Than												and Leases								Loans and
									90 Days																				Leases
	(In Thousands)
Originated:
Commercial real estate loans:
Commercial real estate mortgage	$	1,530			$	—			$	435			$	1,965			$	869,587			$	871,552			$	434			$	1,539
Multi-family mortgage	2,410				60				988				3,458				502,559				506,017				—				1,932
Construction	2,354				816				—				3,170				77,743				80,913				—				—
Total commercial real estate loans	6,294				876				1,423				8,593				1,449,889				1,458,482				434				3,471
Commercial loans and leases:
Commercial	26				75				26				127				230,765				230,892				26				1,993
Equipment financing	2,595				1,439				1,618				5,652				360,645				366,297				—				3,817
Condominium association	—				—				—				—				44,187				44,187				—				8
Total commercial loans and leases	2,621				1,514				1,644				5,779				635,597				641,376				26				5,818
Indirect automobile	5,592				923				99				6,614				535,730				542,344				1				99
Consumer loans:
Residential mortgage	—				—				1,059				1,059				367,036				368,095				27				2,008
Home equity	—				—				33				33				99,650				99,683				—				58
Other consumer	—				2				5				7				6,115				6,122				5				29
Total consumer loans	—				2				1,097				1,099				472,801				473,900				32				2,095
Total originated loans and leases	$	14,507			$	3,315			$	4,263			$	22,085			$	3,094,017			$	3,116,102			$	493			$	11,483
	At December 31, 2012
	Past Due																								Loans and
																									Leases Past
																									Due Greater
																									Than 90 Days
	31-60				61-90				Greater				Total				Current				Total Loans				and Accruing				Nonaccrual
	Days				Days				Than												and Leases								Loans and
									90 Days																				Leases
	(In Thousands)
Acquired:
Commercial real estate loans:
Commercial real estate mortgage	$	2,911			$	—			$	7,289			$	10,200			$	419,481			$	429,681			$	6,616			$	2,475
Multi-family mortgage	2,738				395				2,178				5,311				95,205				100,516				1,857				2,301
Construction	—				—				—				—				17,284				17,284				—				—
Total commercial real estate loans	5,649				395				9,467				15,511				531,970				547,481				8,473				4,776
Commercial loans and leases:
Commercial	866				177				4,353				5,396				145,989				151,385				3,503				3,461
Equipment financing	133				21				194				348				54,346				54,694				197				56
Total commercial loans and leases	999				198				4,547				5,744				200,335				206,079				3,700				3,517
Consumer loans:
Residential mortgage	247				121				5,266				5,634				137,380				143,014				3,650				1,796
Home equity	1,582				507				607				2,696				159,183				161,879				321				658
Other consumer	7				—				—				7				1,150				1,157				—				16
Total consumer loans	1,836				628				5,873				8,337				297,713				306,050				3,971				2,470
Total acquired loans and leases	$	8,484			$	1,221			$	19,887			$	29,592			$	1,030,018			$	1,059,610			$	16,144			$	10,763
Commercial Real Estate Loans—At December 31, 2013, loans outstanding in the three classes within this category expressed as a percentage of total loans and leases outstanding were as follows: commercial real estate mortgage loans 33.5%; multi-family mortgage loans 14.4%; and construction loans 2.6%.
Loans in this portfolio that are on nonaccrual status and/or risk-rated "substandard" or worse are evaluated on an individual loan basis for impairment. For non-impaired commercial real estate loans, loss factors are applied to outstanding loans by risk rating for each of the three classes in the portfolio. The factors applied are based primarily on historic loan loss experience and an assessment of internal and external factors and other relevant information.
Commercial Loans and Leases—At December 31, 2013, loans and leases outstanding in the three classes within this portfolio expressed as a percent of total loans and leases outstanding were as follows: commercial loans and leases 9.3%; equipment financing loans 11.8%; and loans to condominium associations 1.0%.
Loans and leases in this portfolio that are on nonaccrual status and/or risk-rated "substandard" or worse are evaluated on an individual basis for impairment. For non-impaired commercial loans and leases, loss factors are applied to outstanding loans by risk rating for each of the three classes in the portfolio.
Indirect Automobile Loans—At December 31, 2013, indirect automobile loans represented 9.2% of the Company's total loan and lease portfolio. Determination of the allowance for loan and lease losses for this portfolio is based primarily on borrowers' credit scores (generally considered to be a good indicator of capacity to pay a loan, with the risk of loan loss increasing as credit scores decrease), and on an assessment of trends in loan underwriting, loan loss experience, and the economy and industry conditions. Data are gathered on loan originations by year broken down into the following ranges of borrower credit scores: over 700, between 661 and 700, and 660 and below. The Company's loan policy specifies underwriting guidelines based in part on the score of the borrower and includes ceilings on the percent of loans originated that can be to borrowers with credit scores of 660 and below. The breakdown of the amounts shown in "Credit Quality Information" above is based on borrower credit scores at the time of loan origination. It is possible that the credit scores of certain borrowers may have deteriorated since the time the loan was originated. Additionally, migrations of loan charge-offs and recoveries are analyzed by year of origination. Based on that data and taking into consideration other factors such as loan delinquencies and economic conditions, projections are made as to the amount of expected losses inherent in the portfolio. The percentage of loans made to borrowers with credit scores of 660 and below was 3.2% and 3.1% at December 31, 2013 and 2012, respectively.
Consumer Loans—At December 31, 2013, loans outstanding within the three classes within this portfolio expressed as a percent of total loans and leases outstanding (including deferred loan origination costs) were as follows: residential mortgage loans 12.1%, home equity loans 5.9% and other consumer loans 0.2%.
Significant risk characteristics related to the residential mortgage and home equity loan portfolios are the geographic concentration of the properties financed within selected communities in the greater Boston and Providence metropolitan areas and the economic conditions in those areas. The loan-to-value ratio is the primary credit quality indicator used for residential mortgage loans and home equity loans. Generally, loans are not made when the loan-to-value ratio exceeds 80% unless private mortgage insurance is obtained and/or there is a financially strong guarantor. Consumer loans that become 90 days or more past due, or are placed on nonaccrual regardless of past due status, are reviewed on an individual basis for impairment by assessing the net realizable value of underlying collateral and the economic condition of the borrower.
Impaired Loans and Leases
When the ultimate collectability of the total principal of an impaired loan or lease is in doubt and the loan is on nonaccrual status, all payments are applied to principal, under the cost recovery method. When the ultimate collectability of the total principal of an impaired loan or lease is not in doubt and the loan or lease is on nonaccrual status, contractual interest is credited to interest income when received, under the cash basis method.
The following tables include the recorded investment and unpaid principal balances of impaired loans and leases with the related allowance amount, if applicable, for the originated and acquired loan and lease portfolios at the dates and for the periods indicated. Also presented are the average recorded investments in the impaired loans and leases and the related amount of interest recognized during the period that the impaired loans were impaired.
	At December 31, 2013												Year Ended December 31, 2013
	Recorded				Unpaid				Related				Average				Interest
	Investment (1)				Principal				Allowance				Recorded				Income
					Balance								Investment				Recognized
	(In Thousands)
Originated:
With no related allowance recorded:
Commercial real estate	$	2,009			$	2,009			$	—			$	2,184			$	92
Commercial	4,410				4,399				—				4,257				144
Consumer	989				987				—				1,077				30
	7,408				7,395				—				7,518				266
With an allowance recorded:
Commercial real estate	1,466				1,466				184				1,464				43
Commercial	2,393				2,383				675				1,781				29
Consumer	2,448				2,440				323				3,210				97
	6,307				6,289				1,182				6,455				169
Total	$	13,715			$	13,684			$	1,182			$	13,973			$	435
(1) Includes nonaccrual loans of $5.8 million
	At December 31, 2013												Year Ended December 31, 2013
	Recorded				Unpaid				Related				Average				Interest
	Investment (1)				Principal				Allowance				Recorded				Income
					Balance								Investment				Recognized
	(In Thousands)
Acquired:
With no related allowance recorded:
Commercial real estate	$	9,176			$	10,082			$	—			$	9,639			$	251
Commercial	6,988				7,248				—				5,205				129
Consumer	1,033				1,037				—				1,333				20
	17,197				18,367				—				16,177				400
With an allowance recorded:
Commercial real estate	1,274				1,291				122				2,765				42
Commercial	1,020				1,067				169				577				5
Consumer	—				—				—				—				—
	2,294				2,358				291				3,342				47
Total	$	19,491			$	20,725			$	291			$	19,519			$	447
(1) Includes nonaccrual loans of $10.9 million
	At December 31, 2012												Year Ended December 31, 2012
	Recorded				Unpaid				Related				Average				Interest
	Investment (1)				Principal				Allowance				Recorded				Income
					Balance								Investment				Recognized
	(In Thousands)
Originated:
With no related allowance recorded:
Commercial real estate	$	2,051			$	2,051			$	—			$	2,547			$	243
Commercial	3,032				3,059				—				3,159				181
Consumer	1,191				1,187				—				2,123				130
	6,274				6,297				—				7,829				554
With an allowance recorded:
Commercial real estate	2,517				2,516				241				1,142				79
Commercial	3,422				3,559				703				3,393				305
Consumer	3,648				3,636				596				2,918				100
	9,587				9,711				1,540				7,453				484
Total	$	15,861			$	16,008			$	1,540			$	15,282			$	1,038
(1) Includes nonaccrual loans of $8.8 million
	At December 31, 2012												Year Ended December 31, 2012
	Recorded				Unpaid				Related				Average				Interest
	Investment (1)				Principal				Allowance				Recorded				Income
					Balance								Investment				Recognized
	(In Thousands)
Acquired:
With no related allowance recorded:
Commercial real estate	17,918				19,129				—				9,071				—
Commercial	7,329				7,782				—				3,801				—
Consumer	3,266				3,379				—				2,319				—
	28,513				30,290				—				15,191				—
With an allowance recorded:
Commercial real estate	673				684				75				366				—
Commercial	113				121				75				109				—
Consumer	—				—				—				—				—
	786				805				150				475				—
Total	$	29,299			$	31,095			$	150			$	15,666			$	—
(1) Includes nonaccrual loans of $21.5 million
	At December 31, 2011												Year Ended December 31, 2011
	Recorded				Unpaid				Related				Average				Interest
	Investment				Principal				Allowance				Recorded				Income
					Balance								Investment				Recognized
	(In Thousands)
Originated:
With no related allowance recorded:
Commercial real estate	$	2,902			$	3,140			$	—			$	2,834			$	119
Commercial	3,341				4,063				—				2,938				94
Indirect automobile	111				111				—				100				—
Consumer	3,126				3,126				—				3,753				159
	9,480				10,440				—				9,625				372
With an allowance recorded:
Commercial	604				619				190				774				58
Consumer	339				339				35				343				7
	943				958				225				1,117				65
Total	$	10,423			$	11,398			$	225			$	10,742			$	437
There were no changes in the allowance for loan and lease losses associated with acquired loans in 2011.
The following tables present information regarding impaired and non-impaired loans and leases at the dates indicated:
	At December 31, 2013
	Loans and Leases								Loans and Leases								Acquired Loans								Total
	Individually								Collectively Evaluated								(ASC 310-30)
	Evaluated for								for Impairment
	Impairment
	Portfolio				Allowance				Portfolio				Allowance				Portfolio				Allowance				Portfolio				Allowance
	(In Thousands)
Commercial real estate	$	6,269			$	184			$	1,910,645			$	22,282			$	286,709			$	556			$	2,203,623			$	23,022
Commercial	11,512				675				914,739				14,293				39,359				252				965,610				15,220
Indirect automobile	—				—				400,531				3,924				—				—				400,531				3,924
Consumer	4,309				323				708,640				2,618				79,752				434				792,701				3,375
Unallocated	—				—				—				2,932				—				—				—				2,932
Total	$	22,090			$	1,182			$	3,934,555			$	46,049			$	405,820			$	1,242			$	4,362,465			$	48,473
	At December 31, 2012
	Loans and Leases								Loans and Leases								Acquired Loans								Total
	Individually								Collectively Evaluated								(ASC 310-30)
	Evaluated for								for Impairment
	Impairment
	Portfolio				Allowance				Portfolio				Allowance				Portfolio				Allowance				Portfolio				Allowance
	(In Thousands)
Commercial real estate	$	5,576			$	316			$	1,652,231			$	19,702			$	348,156			$	—			$	2,005,963			$	20,018
Commercial	8,046				778				774,366				9,877				65,043				—				847,455				10,655
Indirect automobile	—				—				542,344				5,304				—				—				542,344				5,304
Consumer	5,237				596				672,051				1,949				102,662				—				779,950				2,545
Unallocated	—				—				—				2,630				—				—				—				2,630
Total	$	18,859			$	1,690			$	3,640,992			$	39,462			$	515,861			$	—			$	4,175,712			$	41,152
Troubled Debt Restructured Loans and Leases
The recorded investment in troubled debt restructurings, and the associated specific allowances for loan and lease losses, in the originated and acquired loan and lease portfolios are as follows for the periods indicated:
	Year Ended December 31, 2013
				Recorded Investment								Specific												Defaulted
												Allowance for
												Loan and
	Number of			At				At End of				Lease Losses				Nonaccrual				Additional				Number of			Recorded
	Loans/			Modification				Period								Loans and				Commitment				Loans/			Investment
	Leases															Leases								Leases
	(Dollars in Thousands)
Originated:
Commercial real estate mortgage	1			$	1,039			$	—			$	—			$	—			$	—			—			$	—
Commercial	2			926				918				—				—				—				—			—
Equipment financing	5			1,557				1,415				77				861				—				2			371
Residential mortgage	1			415				353				—				353				—				—			—
Total	9			$	3,937			$	2,686			$	77			$	1,214			$	—			2			$	371
	Year Ended December 31, 2013
				Recorded Investment								Specific												Defaulted
												Allowance for
												Loan and
	Number of			At				At End of				Lease Losses				Nonaccrual				Additional				Number of			Recorded
	Loans/			Modification				Period								Loans and				Commitment				Loans/			Investment
	Leases															Leases								Leases
	(Dollars in Thousands)
Acquired:
Commercial real estate mortgage	1			$	737			$	727			$	—			$	—			$	—			—			$	—
Commercial	6			3,209				3,135				—				1,335				—				1			1,335
Equipment financing	—			—				—				—				—				—				—			—
Residential mortgage	—			—				—				—				—				—				—			—
Total	7			$	3,946			$	3,862			$	—			$	1,335			$	—			1			$	1,335
	Year Ended December 31, 2012
				Recorded Investment								Specific												Defaulted
												Allowance for
												Loan and
	Number of			At				At End of				Lease Losses				Nonaccrual				Additional				Number of			Recorded
	Loans/			Modification				Period								Loans and				Commitment				Loans/			Investment
	Leases															Leases								Leases
	(Dollars in Thousands)
Originated:
Commercial real estate mortgage	2			$	867			$	854			$	33			$	513			$	—			2			$	1,288
Commercial	3			3,942				2,086				316				1,993				—				1			44
Equipment financing	8			2,138				2,038				110				793				—				6			1,240
Residential mortgage	6			2,422				1,724				315				294				—				3			763
Total	19			$	9,369			$	6,702			$	774			$	3,593			$	—			12			$	3,335
	Year Ended December 31, 2012
				Recorded Investment								Specific												Defaulted
												Allowance for
												Loan and
	Number of			At				At End of				Lease Losses				Nonaccrual				Additional				Number of			Recorded
	Loans/			Modification				Period								Loans and				Commitment				Loans/			Investment
	Leases															Leases								Leases
	(Dollars in Thousands)
Acquired:
Commercial real estate mortgage	1			$	3,145			$	3,208			$	—			$	—			$	—			—			$	—
Commercial	2			1,229				1,163				—				478				—				—			—
Equipment financing	—			—				—				—				—				—				—			—
Residential mortgage	—			—				—				—				—				—				—			—
Total	3			$	4,374			$	4,371			$	—			$	478			$	—			—			$	—
	Year Ended December 31, 2011
				Recorded Investment								Specific												Defaulted
												Allowance for
												Loan and
	Number of			At				At End of				Lease Losses				Nonaccrual				Additional				Number of			Recorded
	Loans/			Modification				Period								Loans and				Commitment				Loans/			Investment
	Leases															Leases								Leases
	(Dollars in Thousands)
Originated:
Commercial real estate mortgage	2			$	1,171			$	1,170			$	28			$	—			$	—			—			$	—
Multi-family mortgage	1			29				29				—				29				—				1			29
Commercial	1			66				66				—				—				—				—			—
Equipment financing	16			1,819				1,710				173				524				—				3			365
Residential mortgage	10			1,942				1,937				190				243				—				2			491
Total	30			$	5,027			$	4,912			$	391			$	796			$	—			6			$	885
	Year Ended December 31, 2011
				Recorded Investment								Specific												Defaulted
												Allowance for
												Loan and
	Number of			At				At End of				Lease Losses				Nonaccrual				Additional				Number of			Recorded
	Loans/			Modification				Period								Loans and				Commitment				Loans/			Investment
	Leases															Leases								Leases
	(Dollars in Thousands)
Acquired:
Commercial real estate mortgage	1			$	1,725			$	1,609			$	—			$	1,608			$	—			—			$	—
Multi-family mortgage	—			—				—				—				—				—				—			—
Commercial	—			—				—				—				—				—				—			—
Equipment financing	—			—				—				—				—				—				—			—
Residential mortgage	1			677				652				—				—				—				—			—
Total	2			$	2,402			$	2,261			$	—			$	1,608			$	—			—			$	—
The financial impact of the modification of performing and nonperforming loans and leases for the year ending December 31, 2013 was $0.8 million. There was no financial impact of the modification of performing and nonperforming loans and leases for the year ending December 31, 2012 or 2011.
The following table sets forth the Company's end-of-period balances for troubled debt restructurings that were modified during the periods indicated, by type of modification.
	Year Ended
	December 31,
	2013				2012				2011
	(In Thousands)
Loans modified once:
Extended maturity	$	3,841			$	1,478			$	1,136
Adjusted principal	908				2,185				1,456
Adjusted interest rate	755				1,715				—
Combination maturity, principal, interest rate	554				1,838				1,928
Total loans modified once	$	6,058			$	7,216			$	4,520
Loans modified more than once:
Extended maturity	$	490			$	—			$	78
Adjusted principal	—				3,857				1,471
Adjusted interest rate	—				—				353
Combination maturity, principal, interest rate	—				—				751
Total loans modified more than once	$	490			$	3,857			$	2,653

Premises_and_Equipment

Premises and Equipment	12 Months Ended
	Dec. 31, 2013
Property, Plant and Equipment [Abstract]	'
Premises and Equipment	'
	Premises and Equipment
	Premises and equipment consist of the following:
		At December 31,				Estimated
		2013		2012		Useful Life
		(In Thousands)				(In Years)
	Land	$	7,481	$	7,553	NA
	Office building and improvements	75,271		67,672		10 to 40
	Furniture, fixtures and equipment	25,633		22,537		3 to 10
	Software	5,018		5,063		3 to 7
	Core processing system	11,522		6,951		7.5
	Total	124,925		109,776
	Accumulated depreciation and amortization	44,420		38,985
	Total premises and equipment	$	80,505	$	70,791
	Depreciation and amortization expense is calculated using the straight-line method and is included in occupancy and equipment and data processing expense in the Consolidated Statements of Income. For the years ended December 31, 2013, 2012 and 2011, depreciation and amortization expense related to premises and equipment totaled $6.5 million, $4.0 million and $2.1 million, respectively.

Goodwill_and_Other_Intangible_

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2013
Goodwill and Intangible Assets Disclosure [Abstract]	'
Goodwill and Other Intangible Assets	'
	Goodwill and Other Intangible Assets
	The changes in the carrying value of goodwill for the periods indicated were as follows:
		Year Ended December 31,
		2013		2012			2011
		(In Thousands)
	Balance at beginning of year	$	137,890	$	45,799		$	43,241
	Additions	—		93,145			2,558
	Adjustments to original goodwill	—		(1,054		)	—
	Balance at end of year	$	137,890	$	137,890		$	45,799
	The following is a summary of the Company's other intangible assets:
		At December 31, 2013							At December 31, 2012
		Gross		Accumulated			Carrying		Gross		Accumulated		Carrying
		Amount		Amortization			Amount		Amount		Amortization		Amount
		(In Thousands)
	Other intangible assets:
	Core deposits	$	36,172	$	20,395		$	15,777	$	36,172	$	16,399	$	19,773
	Trade name	1,600		511			1,089		1,600		267		1,333
	Trust relationship	1,568		1,547			21		1,568		1,164		404
	Other intangible	442		442			—		442		442		—
	Total other intangible assets	$	39,782	$	22,895		$	16,887	$	39,782	$	18,272	$	21,510
	As of December 31, 2013, the Company has concluded that the BankRI name will continue to be utilized in its marketing strategies; therefore, the trade name with carrying value of $1.1 million has an indefinite life and ceased to amortize.
	The weighted-average amortization period for core deposit intangible and trust relationships is 11.0 and 1.0 years, respectively. There were no impairment losses relating to other acquisition-related intangible assets recorded during the years ended December 31, 2013, 2012 and 2011.
	The estimated aggregate future amortization expense for other intangible assets for each of the next five years and thereafter is as follows:
	Year ended December 31:	Amount
		(In Thousands)
	2014	$	3,124
	2015	2,868
	2016	2,457
	2017	1,858
	2018	1,836
	Thereafter	3,655
	Total	$	15,798

Other_Assets

Other Assets	12 Months Ended
	Dec. 31, 2013
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]	'
Other Assets	'
	Other Assets
	BOLI
	BOLI is recorded at the cash surrender value of the policies, less any applicable cash surrender charges, and is recorded in other assets. At December 31, 2013 and 2012, BankRI owned nine policies with a net cash surrender value of $34.7 million and $33.7 million, respectively. At both December 31, 2013 and 2012, First Ipswich owned two policies with a net cash surrender value of $0.7 million.
	Affordable Housing Investments
	The Company began investing in affordable housing projects that benefit low- and moderate-income individuals in 2011 and currently has investments in seven projects. During 2013, the Company invested in two new affordable housing projects for a total of $3.3 million. The Company is a limited partner in these projects given that its investments do not exceed 50% of the outstanding equity interest in any single project and project management is controlled by the general partner or project sponsor. Further information regarding the Company's investments in affordable housing projects follows:
		As of and for the
		Year Ended
		December 31,
		2013		2012		2011
		(In Thousands)
	Investments in affordable housing projects included in other assets	$	10,301	$	9,167	$	6,712
	Unfunded commitments related to affordable housing projects included in other liabilities	2,904		4,291		2,864
	Loss from investments in affordable housing projects	1,812		694		671
	Reduction in tax expense due to affordable housing tax credits	1,058		806		464

Deposits

Deposits	12 Months Ended
	Dec. 31, 2013
Deposits [Abstract]	'
Deposits	'
	Deposits
	A summary of deposits follows:
		31-Dec-13				31-Dec-12
		Amount		Weighted		Amount			Weighted
				Average					Average
				Rate					Rate
		(Dollars in Thousands)
	Demand checking accounts	$	707,023	—		$	623,274		—
	NOW accounts	210,602		0.07	%	212,858			0.09	%
	Savings accounts	494,734		0.25	%	515,367			0.39	%
	Money market accounts	1,487,979		0.54	%	1,253,819			0.63	%
	Total core deposit accounts	2,900,338		0.32	%	2,605,318			0.39	%
	Certificate of deposit accounts maturing:
	Within six months	381,986		0.72	%	392,138			0.91	%
	After six months but within 1 year	312,005		0.82	%	359,510			0.95	%
	After 1 year but within 2 years	141,518		1.09	%	159,747			1.09	%
	After 2 years but within 3 years	45,965		1.91	%	34,392			2.05	%
	After 3 years but within 4 years	26,046		1.65	%	37,813			2.08	%
	After 4 years but within 5 years	26,810		1.33	%	27,341			1.65	%
	5+ Years	338		1.15	%	—			—	%
	Total certificate of deposit accounts	934,668		0.91	%	1,010,941			1.06	%
	Total deposits	$	3,835,006	0.47	%	$	3,616,259		0.58	%
	Certificate of deposit accounts issued in amounts of $100,000 or more totaled $424.7 million and $437.9 million at December 31, 2013 and 2012, respectively.
	Interest expense on deposit balances is summarized as follows:
		Year Ended December 31,
		2013		2012			2011
		(In Thousands)
	Interest-bearing deposits:
	NOW accounts	$	173	$	209		$	216
	Savings accounts	1,288		1,726			942
	Money market accounts	8,220		8,773			7,626
	Certificate of deposit accounts	9,092		10,724			10,973
	Total interest-bearing deposits	$	18,773	$	21,432		$	19,757
	Collateral Pledged to Deposits
	At December 31, 2013 and 2012, $62.4 million and $86.5 million, respectively, of collateral was pledged for municipal deposits; treasury; tax and loan deposits.

Borrowed_Funds

Borrowed Funds	12 Months Ended
	Dec. 31, 2013
Debt Disclosure [Abstract]	'
Borrowed Funds	'
	Borrowed Funds
	Borrowed funds are comprised of the following:
		At December 31,
		2013				2012
		(In Thousands)
	Advances from the FHLBB	$	768,773			$	790,865
	Repurchase agreements	34,619				51,013
	Subordinated debentures	9,163				12,091
	Total borrowed funds	$	812,555			$	853,969
	Interest expense on borrowed funds for the periods indicated is as follows:
		Year Ended December 31,
		2013				2012			2011
		(In Thousands)
	Advances from the FHLBB	$	10,886			$	13,685		$	10,454
	Repurchase agreements	68				137			125
	Subordinated debentures	439				578			—
	Total interest expense on borrowed funds	$	11,393			$	14,400		$	10,579
	Investment Securities and Loans Pledged as Collateral
	At December 31, 2013 and 2012, $1.6 billion and $1.8 billion, respectively, of investment securities available-for-sale and loans and leases, were pledged as collateral for repurchase agreements; municipal deposits; treasury; tax and loan deposits; swap agreements; current and future FHLBB borrowings; and future Federal Reserve "discount window" borrowings.
	FHLBB Advances and Federal Reserve Borrowings
	FHLBB advances mature as follows:
		At December 31,
		2013										2012
		Amount				Callable			Weighted			Amount		Callable		Weighted
						Amount			Average					Amount		Average
									Rate							Rate
		(Dollars in Thousands)
	Within 1 year	$	186,035			$	—		0.71	%		$	363,485	$	17,000	1.32	%
	Over 1 year to 2 years	283,000				—			0.79	%		46,178		—		2.14	%
	Over 2 years to 3 years	92,971				32,094			2.45	%		108,000		—		1	%
	Over 3 years to 4 years	147,198				118,698			3.86	%		64,330		30,000		3.24	%
	Over 4 years to 5 years	36,625				10,071			2.51	%		149,032		112,000		3.86	%
	Over 5 years	22,944				—			3.7	%		59,840		10,000		3	%
		$	768,773			$	160,863		1.71	%		$	790,865	$	169,000	2.06	%
	Actual maturities of the advances may differ from those presented above since the FHLBB has the right to call certain advances prior to the scheduled maturity.
	The advances are secured by blanket pledge agreements which require the Banks to maintain as collateral certain qualifying assets, principally the Banks' FHLBB stock, mortgage loans and securities in an aggregate amount equal to outstanding advances. Based on the $1.6 billion in qualifying collateral available for these borrowings, at December 31, 2013 the total available borrowing capacity for advances from the FHLBB and FRB was $1.0 billion.
	Repurchase Agreements
	Information concerning repurchase agreements is as follows for the periods indicated below:
		Year Ended December 31,
		2013				2012
		(Dollars In Thousands)
	Outstanding at end of year	$	34,619			$	51,013
	Average outstanding for the year	38,784				46,623
	Maximum outstanding at any month-end	48,544				51,013
	Weighted average rate at end of year	0.17		%		0.15		%
	Weighted average rate paid for the year	0.17		%		0.13		%
	Securities sold under agreements to repurchase are funds borrowed from customers on an overnight basis that are secured by GSEs in the same amount. The obligations to repurchase the identical securities that were sold are reflected as liabilities and the securities remain in the asset accounts.
	Subordinated Debentures
	In the acquisition of Bancorp Rhode Island, Inc., the Company assumed three subordinated debentures issued by a subsidiary of Bancorp Rhode Island, Inc. One subordinated debenture in the amount of $3.0 million was called in the first quarter of 2013 million due to its high fixed rate. The two remaining subordinated debentures are summarized below:
	At December 31, 2013:
	Issue Date		Rate		Fair			Maturity Date	Next Call Date		Carrying
					Market Rate						Amount
					at BankRI
					Acquisition
			(Dollars in Thousands)
	June 26, 2003		Variable; 3-month		6.45	%		June 26, 2033	March 26, 2014		$	4,666
			LIBOR + 3.10%
	March 17, 2004		Variable; 3-month		6.45	%		March 17, 2034	March 17, 2014		$	4,497
			LIBOR + 2.79%
	At December 31, 2012:
	Issue Date		Rate		Fair			Maturity Date	Next Call Date		Carrying
					Market Rate						Amount
					at BankRI
Acquisition
		(Dollars in Thousands)
22-Feb-01		Fixed; 10.2%		3	%		22-Feb-31	22-Feb-13		$	3,000
June 26, 2003		Variable; 3-month		6.45	%		June 26, 2033	March 26, 2013		$	4,641
		LIBOR + 3.10%
March 17, 2004		Variable; 3-month		6.45	%		March 17, 2034	March 17, 2013		$	4,450
		LIBOR + 2.79%

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2013
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	Commitments and Contingencies
	Off-Balance Sheet Financial Instruments
	The Company is party to off-balance sheet financial instruments in the normal course of business to meet the financing needs of its customers and to reduce its own exposure to fluctuations in interest rates. These financial instruments include loan commitments, standby and commercial letters of credits, and interest rate swaps. According to GAAP, these financial instruments are not recorded in the financial statements until they are funded or related fees are incurred or received.
	The contract amounts reflect the extent of the involvement the Company has in particular classes of these instruments. Such commitments involve, to varying degrees, elements of credit risk and interest-rate risk in excess of the amount recognized in the consolidated balance sheets. The Company's exposure to credit loss in the event of non-performance by the counterparty is represented by the contractual amount of the instruments. The Company uses the same policies in making commitments and conditional obligations as it does for on-balance sheet instruments.
	Financial instruments with off-balance-sheet risk at the dates indicated follow:
		At December 31,
		2013		2012
		(In Thousands)
	Financial instruments whose contract amounts represent credit risk:
	Commitments to originate loans and leases:
	Commercial real estate	$	48,973	$	158,768
	Commercial	143,252		116,235
	Residential mortgage	8,027		8,926
	Unadvanced portion of loans and leases	592,782		299,523
	Unused lines of credit:
	Home equity	205,665		165,936
	Other consumer	1,035		4,017
	Other commercial	—		965
	Unused letters of credit:
	Financial standby letters of credit	20,410		19,887
	Performance standby letters of credit	2,989		2,916
	Commercial and similar letters of credit	440		112
	Back-to-back interest rate swaps	22,418		33,221
	Commitments to extend credit are agreements to lend to a customer as long as there is no violation of any condition established in the contract. Commitments generally have fixed expiration dates or other termination clauses and may require the payment of a fee by the customer. Since some of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. The Company evaluates each customer's creditworthiness on a case-by-case basis. The amount of collateral obtained, if any, is based on management's credit evaluation of the borrower.
	Standby and commercial letters of credits are conditional commitments issued by the Company to guarantee performance of a customer to a third party. These standby and commercial letters of credit are primarily issued to support the financing needs of the Company's commercial customers. The credit risk involved in issuing letters of credit is essentially the same as that involved in extending loans to customers.
	The liability for unfunded credit commitments, which is included in other liabilities, was $1.0 million at December 31, 2013 and $0.7 million at December 31, 2012.
	From time to time the Company enters into back-to-back interest rate swaps with commercial customers and third-party financial institutions. These swaps allow the Company to offer long-term fixed-rate commercial loans while mitigating the interest-rate risk of holding those loans. In a back-to-back interest rate swap transaction, the Company lends to a commercial customer on a floating-rate basis and then enters into an interest rate swap with that customer. Concurrently, the Company enters into offsetting swaps with a third-party financial institution, effectively minimizing its net interest-rate risk exposure resulting from such transactions.
	The fair value of interest rate swap assets and liabilities is $0.8 million and $0.9 million, respectively, at December 31, 2013. The fair value of interest rate swap assets and liabilities is $1.3 million and $1.4 million, respectively, at December 31, 2012.
	Lease Commitments
	The Company leases certain office space under various noncancellable operating leases. A summary of future minimum rental payments under such leases at the dates indicated follows:
	Year ended December 31,	Minimum Rental Payments
		(In Thousands)
	2014	$	4,936
	2015	4,740
	2016	4,500
	2017	4,030
	2018	3,392
	Thereafter	12,431
	Total	$	34,029
	The leases contain escalation clauses for real estate taxes and other expenditures, which are not included above. Total rental expense was $5.2 million in 2013, $4.5 million in 2012 and$2.7 million in 2011.
	A portion of the Company's new headquarters was rented to third-party tenants in 2013 with rental income of $0.3 million reported in non-interest income.
	Legal Proceedings
	In the normal course of business, there are various outstanding legal proceedings. In the opinion of management, after consulting with legal counsel, the consolidated financial position and results of operations of the Company are not expected to be affected materially by the outcome of such proceedings.

Earnings_per_Share

Earnings per Share	12 Months Ended
	Dec. 31, 2013
Earnings Per Share [Abstract]	'
Earnings per Share	'
	Earnings per Share
	The following table is a reconciliation of basic EPS and diluted EPS:
		2013				2012				2011
		Basic		Fully		Basic		Fully		Basic		Fully
				Diluted				Diluted				Diluted
		(Dollars in Thousands, Except Per Share Amounts)
	Net income	$	35,386	$	35,386	$	37,142	$	37,142	$	27,600	$	27,600
	Weighted average shares outstanding	69,808,164		69,808,164		69,702,417		69,702,417		58,633,627		58,633,627
	Effect of dilutive securities	—		75,760		—		43,839		—		2,804
	Adjusted weighted average shares outstanding	69,808,164		69,883,924		69,702,417		69,746,256		58,633,627		58,636,431
	Earnings per share	$	0.51	$	0.51	$	0.53	$	0.53	$	0.47	$	0.47
	On January 3, 2012, the Company issued approximately 11 million shares of common stock as partial consideration to acquire Bancorp Rhode Island, Inc. (Refer to Note 2, "Acquisitions,")

Comprehensive_Income

Comprehensive Income	12 Months Ended
	Dec. 31, 2013
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]	'
Comprehensive Income	'
	Comprehensive Income
	Comprehensive income represents the sum of net income (loss) and other comprehensive income (loss). For the years ended December 31, 2013, 2012 and 2011, the Company’s other comprehensive income include the following two components: (i) unrealized holding gains (losses) on investment securities available-for-sale; and (ii) adjustment of accumulated obligation for postretirement benefits.
	Changes in accumulated other comprehensive (loss) income by component, net of tax, were as follows for the periods indicated:
		Year Ended December 31, 2013
		Investment			Postretirement			Accumulated Other
		Securities			Benefits			Comprehensive
		Available-for-Sale						Income
		(In Thousands)
	Balance at December 31, 2012	$	3,358		$	125		$	3,483
	Other comprehensive (loss) income	(11,690		)	292			(11,398		)
	Balance at December 31, 2013	$	(8,332	)	$	417		$	(7,915	)
		Year Ended December 31, 2012
		Investment			Postretirement			Accumulated Other
		Securities			Benefits			Comprehensive
		Available-for-Sale						Income
		(In Thousands)
	Balance at December 31, 2011	$	1,834		$	129		$	1,963
	Other comprehensive income (loss)	1,524			(4		)	1,520
	Balance at December 31, 2012	$	3,358		$	125		$	3,483
		Year Ended December 31, 2011
		Investment			Postretirement			Accumulated Other
		Securities			Benefits			Comprehensive
		Available-for-Sale						Income
		(In Thousands)
	Balance at December 31, 2010	$	2,185		$	163		$	2,348
	Other comprehensive loss	(351		)	(34		)	(385		)
	Balance at December 31, 2011	$	1,834		$	129		$	1,963
	The following is a summary of the amounts reclassified from accumulated other comprehensive income (loss) for the years ended December 31, 2013, 2012, and 2011.
		Year Ended December 31,									Income Statement Line Affected by Reclassification
		2013			2012			2011
		(In Thousands)
	Other Comprehensive Income (Loss) Component
	Unrealized gains on investment securities available-for-sale:
		$	397		$	926		$	80		Gain on sales of securities,net
		(142		)	(328		)	(29		)	Provision for income taxes
	Total reclassifications for the period	$	255		$	598		$	51		Net income

Derivatives_and_Hedging_Activi

Derivatives and Hedging Activities	12 Months Ended
	Dec. 31, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Derivatives and Hedging Activities	'
	Derivatives and Hedging Activities
	The Company may use interest-rate contracts (swaps, caps and floors) as part of interest-rate risk management strategy. Interest-rate swap, cap and floor agreements are entered into as hedges against future interest-rate fluctuations on specifically identified assets or liabilities. The Company did not have derivative fair value hedges or derivative cash flow hedges at December 31, 2013 and 2012.
	Derivatives not designated as hedges are not speculative but rather, result from a service the Company provides to certain customers for a fee. The Company executes interest-rate swaps with commercial banking customers to aid them in managing their interest-rate risk. The interest-rate swap contracts allow the commercial banking customers to convert floating-rate loan payments to fixed-rate loan payments. The Company concurrently enters into offsetting swaps with a third-party financial institution, effectively minimizing its net risk exposure resulting from such transactions. The third-party financial institution exchanges the customer's fixed-rate loan payments for floating-rate loan payments. As the interest-rate swaps associated with this program do not meet hedge accounting requirements, changes in the fair value of both the customer swaps and the offsetting swaps are recognized directly in earnings. The Company had 8 interest-rate swaps with an aggregate notional amount of $22.4 million and 10 interest-rate swaps with an aggregate notional amount of $33.2 million related to this program at December 31, 2013 and 2012, respectively.
	The table below presents the fair value and classification of the Company's derivative financial instruments on the consolidated balance sheets as of December 31, 2013 and 2012, and the effect of the Company's derivative financial instruments on the consolidated income statements for the year ended December 31, 2013 and 2012:
		At December 31, 2013				Year Ended
						December 31, 2013
		Asset		Liability		Loss Recognized in
		Derivatives		Derivatives		Income on Derivatives(1)
		(In Thousands)
	Total derivatives (interest-rate products) not designated as hedging instruments	$	825	$	856	$	32
		At December 31, 2012				Year Ended
						December 31, 2012
		Asset		Liability		Loss Recognized in
		Derivatives		Derivatives		Income on Derivatives(1)
		(In Thousands)
	Total derivatives (interest-rate products) not designated as hedging instruments	$	1,317	$	1,380	$	24
	_______________________________________________________________________________
	-1	The amount of loss recognized in income represents changes related to the fair value of the interest rate products.
	By using derivative financial instruments, the Company exposes itself to credit risk. Credit risk is the risk of failure by the counterparty to perform under the terms of the derivative contract. When the fair value of a derivative contract is positive, the counterparty owes the Company, which creates credit risk for the Company. When the fair value of a derivative is negative, the Company owes the counterparty and, therefore, it does not possess credit risk. The credit risk in derivative instruments is mitigated by entering into transactions with highly-rated counterparties that management believes to be creditworthy and by limiting the amount of exposure to each counterparty. The Company had limited exposure relating to interest rate swaps with institutional counterparties at December 31, 2012 or 2011, as all such swaps were in a net liability position and subject to master netting agreements.
	The estimated net credit risk exposure for derivative financial instruments was $31.2 thousand and $0.1 million at December 31, 2013, and 2012, respectively.
	Certain of the derivative agreements contain provisions that require the Company to post collateral if the derivative exposure exceeds a threshold amount. The Company posted collateral in the normal course of business totaling $2.8 million and $0.5 million as of December 31, 2013 and 2012, respectively.
	The tables below present the offsetting of derivatives and amounts subject to master netting agreements not offset in the consolidated balance sheet at the dates indicated.
		At December 31, 2013
		Gross		Gross Amounts		Net Amounts of		Gross Amounts Not Offset in the				Net Amount
		Amounts of		Offset in the		Assets Presented in		Statement of Financial Position
		Recognized		Statement of Financial Position		the Statement of Financial Position
		Assets /Liabilities						Financial Instruments		Cash Collateral (Received)/ Posted
		(In Thousands)
	Asset Derivatives	$	825	$	—	$	825	$	—	$	—	$	825
	Liability Derivatives	$	856	$	—	$	856	$	—	$	2,811	$	3,667
		At December 31, 2012
		Gross		Gross Amounts		Net Amounts of		Gross Amounts Not Offset in the				Net Amount
		Amounts of		Offset in the		Assets Presented in		Statement of Financial Position
		Recognized		Statement of Financial Position		the Statement of Financial Position
		Assets /Liabilities						Financial Instruments		Cash Collateral (Received) / Posted
		(In Thousands)
	Asset Derivatives	$	1,317	$	—	$	1,317	$	—	$	—	$	1,317
	Liability Derivatives	$	1,380	$	—	$	1,380	$	—	$	548	$	1,928
	The Company has agreements with certain of its derivative counterparties that contain credit-risk-related contingent provisions. These provisions provide the counterparty with the right to terminate its derivative positions and require the Company to settle its obligations under the agreements if the Company defaults on certain of its indebtedness or if the Company fails to maintain its status as a well-capitalized institution.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes
	Income tax expense is comprised of the following amounts:
		Year Ended December 31,
		2013			2012			2011
		(In Thousands)
	Current provision:
	Federal	$	12,799		$	15,558		$	14,115
	State	4,238			5,120			4,987
	Total current provision	17,037			20,678			19,102
	Deferred provision (benefit):
	Federal	2,572			389			811
	State	(128		)	274			(27		)
	Total deferred provision	2,444			663			784
	Total provision for income taxes	$	19,481		$	21,341		$	19,886
	Total provision for income taxes differed from the amounts computed by applying the statutory U.S. federal income tax rate (35.0%) to income before tax expense as a result of the following:
		Year Ended December 31,
		2013			2012			2011
		(In Thousands)
	Expected income tax expense at statutory federal tax rate	$	19,830		$	20,899		$	17,047
	State taxes, net of federal income tax benefit	2,673			3,506			3,224
	Bank-owned life insurance	(383		)	(409		)	—
	Tax-exempt interest income	(310		)	(216		)	(157		)
	Non-deductible acquisition and other expenses	—			617			613
	Income attributable to noncontrolling interest in subsidiary	(768		)	(560		)	(427		)
	Tax credit—premises and equipment	(453		)	(1,593		)	—
	Tax credits from investments in affordable housing projects	(1,058		)	(806		)	(464		)
	Other, net	(50		)	(97		)	50
	Total provision for income taxes	$	19,481		$	21,341		$	19,886
	Effective income tax rate	34.4		%	35.7		%	40.8		%
	The Company's effective tax rate was 34.4% at December 31, 2013 compared to 35.7% at December 31, 2012. The decrease in the Company's effective tax rate in 2013 was primarily attributable to non deductible professional fees in 2012 related to the BankRI acquisition and lower state income tax expense. Additional state income tax expense was recognized in 2012 as the projected state tax savings from the acquisition of BankRI reduced the value of the deferred tax asset by $0.5 million, increasing the income tax expense in 2012. These reductions were partially offset by a $1.1 million reduction in the rehabilitation tax credits received for the refurbishment of the corporate headquarters at 131 Clarendon Street in Boston, Massachusetts as renovations were completed early in 2013.
	The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and liabilities at the dates indicated are as follows:
		At December 31,
		2013			2012
		(In Thousands)
	Deferred tax assets:
	Allowance for credit losses	$	19,754		$	16,667
	Acquisition fair value adjustments	7,430			10,013
	Unrealized loss on securities available for sale	5,119			—
	Retirement and postretirement benefits	4,159			4,822
	Deferred compensation	1,989			2,254
	Net operating loss and contribution carryovers	1,922			2,229
	Non-accrual interest	878			948
	Restricted stock and stock option plans	726			803
	Write-downs of investment securities	442			795
	Depreciation	—			235
	Accrued expenses	375			200
	Alternative minimum tax credits	31			31
	Other	33			198
	Total gross deferred tax assets	42,858			39,195
	Deferred tax liabilities:
	Identified intangible assets and goodwill	7,322			8,893
	Depreciation	2,619			—
	Unrealized gain on securities available for sale	—			2,015
	Deferred loan origination costs, net	734			736
	Investments in affordable housing projects	205			246
	Unrecognized gain relating to postretirement obligation	268			92
	Other	—			16
	Total gross deferred tax liabilities	11,148			11,998
	Net deferred tax asset	$	31,710		$	27,197
	At December 31, 2013, the Company had net operating loss carryforwards for federal income tax purposes of $5.5 million which are available to offset future federal taxable income, if any, through 2020. In addition, the Company has alternative minimum tax credit carryforwards of $31,000, which are available to reduce future federal income taxes, if any, over an indefinite period. According to Section 382 of the Internal Revenue Code, the net operating loss carryforwards and credit are subject to an annual limitation of $881,000.
	The Company has determined that a valuation allowance is not required for any of its deferred tax assets because it believes that it is more likely than not that these assets will reverse against future taxable income.
	For federal income tax purposes, the Company has a $1.8 million reserve for credit losses which remains subject to recapture. If any portion of the reserve is used for purposes other than to absorb the losses for which it was established, approximately 150% of the amount actually used (limited to the amount of the reserve) would be subject to taxation in the year in which used. As the Company intends to use the reserve only to absorb credit losses, no provision has been made for the $750,000 liability that would result if 100% of the reserve were recaptured.
	The Company did not have any unrecognized tax benefits accrued as income tax receivables or as deferred tax items at December 31, 2013.
The Company is subject to federal and state examinations for tax years after December 31, 2009.

Stockholders_Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2013
Stockholders' Equity Note [Abstract]	'
Stockholders' Equity	'
	Stockholders' Equity
	Preferred Stock
	The Company is authorized to issue 50,000,000 shares of serial preferred stock, par value $0.01 per share, from time to time in one or more series subject to limitations of law. The Board of Directors is authorized to fix the designations, powers, preferences, limitations and rights of the shares of each such series. As of December 31, 2013, there were no shares of preferred stock issued.
	Capital Distributions and Restrictions Thereon
	The Company is a legal entity separate and distinct from each of the Banks and Brookline Securities Corp. The Company's primary source of revenue dividends paid to it by the Banks and Brookline Securities Corp.
	The FRB has authority to prohibit the Company from paying dividends to the Company's shareholders if such payment is deemed to be an unsafe or unsound practice. The FRB has indicated generally that it may be an unsafe or unsound practice for bank holding companies to pay dividends unless the bank holding company's net income over the preceding year is sufficient to fund the dividends and the expected rate of earnings retention is consistent with the organization's capital needs, asset quality and overall financial condition.
	The FRB also has the authority to use its enforcement powers to prohibit the Banks from paying dividends to their parent if, in its opinion, the payment of dividends would constitute an unsafe or unsound practice. Federal law also prohibits the payment of dividends by a bank that will result in the bank failing to meet its applicable capital requirements on a pro forma basis. Payment of dividends by a bank is also restricted pursuant to various state regulatory limitations, including the Massachusetts Division of Banks in the case of Brookline Bank and First Ipswich, and the Banking Division of the Rhode Island Department of Business Regulation in the case of BankRI.
	Common Stock Repurchases
	In 2013, 2012 and 2011, no shares of the Company's common stock were repurchased by the Company. As of December 31, 2013, the Company was not authorized to repurchase any additional shares of its common stock.
	Restricted Retained Earnings
	As part of the stock offering in 2002 and as required by regulation, Brookline Bank established a liquidation account for the benefit of eligible account holders and supplemental eligible account holders who maintain their deposit accounts at Brookline Bank after the stock offering. In the unlikely event of a complete liquidation of Brookline Bank (and only in that event), eligible depositors who continue to maintain deposit accounts at Brookline Bank shall be entitled to receive a distribution from the liquidation account.
	Accordingly, retained earnings of the Company are deemed to be restricted up to the balance of the liquidation account. The liquidation account balance is reduced annually to the extent that eligible depositors have reduced their qualifying deposits as of each anniversary date. Subsequent increases in deposit account balances do not restore an account holder's interest in the liquidation account.
	The liquidation account totaled $20.6 million (unaudited), $22.3 million (unaudited) and $24.4 million (unaudited) at December 31, 2013, 2012 and 2011, respectively.

Regulatory_Capital_Requirement

Regulatory Capital Requirements	12 Months Ended
	Dec. 31, 2013
Regulatory Capital Requirements [Abstract]	'
Regulatory Capital Requirements	'
	Regulatory Capital Requirements
	The Company's primary source of cash is dividends from the Banks and Brookline Securities Corp. The Banks are subject to certain restrictions on the amount of dividends that they may declare without prior regulatory approval. In addition, the dividends declared cannot be in excess of the amount which would cause the Banks to fall below the minimum required for capital adequacy purposes.
	The Company is a bank holding company within the meaning of the Bank Holding Company Act of 1956, as amended (the "BHCA") and as such, must comply with the capital requirements of the Federal Reserve Bank (the "FRB") at the consolidated level. As member banks of the FRB, Brookline Bank, BankRI and First Ipswich are also required to comply with the regulatory capital requirement of the FRB.
	While the FRB is the primary regulator, the Banks are also subject to FDIC regulations and capital adequacy requirements since they are also FDIC-insured banks. The FDIC has promulgated corresponding regulations to implement the system of prompt corrective action established by Section 38 of the Federal Deposit Insurance Act, as amended (the "FDIA"). Under the regulations, a bank is "well-capitalized" if it has: (1) a total risk-based capital ratio of 10.0% or greater; (2) a Tier 1 risk-based capital ratio of 6.0% or greater; (3) a Tier 1 leverage ratio of 5.0% or greater; and (4) is not subject to any written agreement, order, capital directive or prompt corrective action directive to meet and maintain a specific capital level for any capital measure.
	Failure to meet minimum capital requirements can initiate certain mandatory and possibly additional discretionary actions by regulators that, if undertaken, could have a direct material effect on the Company's financial statements. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, the Company and Banks must meet specific capital guidelines that involve quantitative measures of the Company's and the Banks' assets, liabilities and certain off-balance sheet items as calculated under regulatory accounting practices. The Company's and the Banks' capital amounts and classification are also subject to qualitative judgments by the regulators about components, risk weightings, and other factors. Prompt corrective action provisions are not applicable to bank holding companies.
	The following table reconciles stockholders' equity under GAAP with regulatory capital for the Company and its subsidiaries at the dates indicated.
		The Company								Brookline Bank						BankRI					First Ipswich
		Dec. 31,								Dec. 31,						Dec. 31,					Dec. 31,
		2013				2012				2013			2012			2013			2012		2013			2012
		(In Thousands)
	Stockholders' equity	$	613,867			$	612,097			$	301,291		$	288,859		$	236,579		$	247,606	$	34,641		$	35,515
	Add: Minority interest	4,304				3,712				4,304			3,712			—			—		—			—
	Add: Subordinated debenture	9,163				12,091				—			—			—			—		—			—
	Less: Disallowed goodwill and intangible assets	154,777				159,400				7,647			7,991			106,593			110,203		5,271			5,940
	Less: Unrealized loss on available-for-sale equity securities	—				—				—			—			—			—		10			—
	Less: Net unrealized (losses) gains on available-for-sale securities	(7,915		)		3,358				(1,874		)	1,874			(4,918		)	1,303		(1,075		)	366
	Tier 1 capital	480,472				465,142				299,822			282,706			134,904			136,100		30,435			29,209
	Allowance for credit losses not to exceed 1.25% of risk-weighted assets	49,510				41,935				35,905			35,923			10,936			5,053		1,854			959
	Unrealized gains on available-for-sale equity securities	—				—				—			—			7			18		—			—
	Total risk-based capital	$	529,982			$	507,077			$	335,727		$	318,629		$	145,847		$	141,171	$	32,289		$	30,168
	As of December 31, 2013, the Company, Brookline Bank, BankRI and First Ipswich met all applicable minimum capital requirements and were considered "well-capitalized" by their respective regulators. The Company's and the Banks' actual and required capital amounts and ratios are as follows:
				Actual							Minimum Required for					Minimum Required
											Capital Adequacy					To Be Considered
											Purposes					"Well-Capitalized"
				Amount				Ratio			Amount			Ratio		Amount			Ratio
				(Dollars in Thousands)
	At December 31, 2013:
	Brookline Bancorp, Inc.
	Tier 1 leverage capital ratio	(1	)	$	480,472			9.4	%		$	205,946		4	%	N/A			N/A
	Tier 1 risk-based capital ratio	(2	)	480,472				11	%		174,512			4	%	N/A			N/A
	Total risk-based capital ratio	(3	)	529,982				12.2	%		349,159			8	%	N/A			N/A
	Brookline Bank
	Tier 1 leverage capital ratio	(1	)	$	299,822			9.4	%		$	127,992		4	%	$	159,990		5	%
	Tier 1 risk-based capital ratio	(2	)	299,822				10.4	%		114,874			4	%	172,311			6	%
	Total risk-based capital ratio	(3	)	335,727				11.7	%		229,753			8	%	287,192			10	%
	BankRI
	Tier 1 leverage capital ratio	(1	)	$	134,904			8.1	%		$	66,784		4	%	$	83,480		5	%
	Tier 1 risk-based capital ratio	(2	)	134,904				10.6	%		52,904			4	%	79,355			6	%
	Total risk-based capital ratio	(3	)	145,847				11.4	%		105,782			8	%	132,228			10	%
	First Ipswich
	Tier 1 leverage capital ratio	(1	)	$	30,435			9.8	%		$	12,461		4	%	$	15,576		5	%
	Tier 1 risk-based capital ratio	(2	)	30,435				13.6	%		8,971			4	%	13,457			6	%
	Total risk-based capital ratio	(3	)	32,289				14.4	%		17,938			8	%	22,423			10	%
	At December 31, 2012:
	Brookline Bancorp, Inc.
	Tier 1 leverage capital ratio	(1	)	$	465,142			9.4	%		$	197,094		4	%	N/A			N/A
	Tier 1 risk-based capital ratio	(2	)	465,142				10.9	%		171,481			4	%	N/A			N/A
	Total risk-based capital ratio	(3	)	507,077				11.8	%		342,909			8	%	N/A			N/A
	Brookline Bank
	Tier 1 leverage capital ratio	(1	)	$	282,706			9.3	%		$	121,725		4	%	$	152,156		5	%
	Tier 1 risk-based capital ratio	(2	)	282,706				9.8	%		115,626			4	%	173,439			6	%
	Total risk-based capital ratio	(3	)	318,629				11	%		231,310			8	%	289,137			10	%
	BankRI
	Tier 1 leverage capital ratio	(1	)	$	136,100			8.5	%		$	64,047		4	%	$	80,059		5	%
	Tier 1 risk-based capital ratio	(2	)	136,100				11.5	%		47,175			4	%	70,763			6	%
	Total risk-based capital ratio	(3	)	141,171				12	%		94,350			8	%	117,937			10	%
	First Ipswich
	Tier 1 leverage capital ratio	(1	)	$	29,209			9.7	%		$	12,020		4	%	$	15,025		5	%
	Tier 1 risk-based capital ratio	(2	)	29,209				13.2	%		8,824			4	%	13,237			6	%
	Total risk-based capital ratio	(3	)	30,168				13.7	%		17,642			8	%	22,053			10	%
	_______________________________________________________________________________
	-1	Tier 1 leverage capital ratio is calculated by dividing Tier 1 capital by average assets.
	-2	Tier 1 risk-based capital ratio is calculated by dividing Tier 1 capital by risk-weighted assets.
-3	Total risk-based capital ratio is calculated by dividing total capital by risk-weighted assets.

Employee_Benefit_Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]	'
Employee Benefit Plans	'
	Employee Benefit Plans
	Postretirement Benefits
	Postretirement benefits are provided for part of the annual expense of health insurance premiums for retired employees and their dependents. No contributions are made by the Company to invest in assets allocated for the purpose of funding this benefit obligation.
	The following table presents the components of net periodic postretirement benefit cost and other amounts recognized in other comprehensive income:
		Year Ended
		December 31,
		2013				2012				2011
		(In Thousands)
	Net periodic benefit expense:
	Service cost	$	61			$	74			$	74
	Interest cost	47				55				61
	Prior service credit	(21		)		(21		)		(21		)
	Actuarial gain	(16		)		(3		)		(4		)
	Net periodic benefit expense	$	71			$	105			$	110
	Changes in postretirement benefit obligation recognized in other comprehensive income:
	Net actuarial loss (gain)	$	489			$	11			$	(36	)
	Prior service credit	(21		)		(21		)		(21		)
	Total pre-tax changes in postretirement benefit obligation recognized in other comprehensive income	$	468			$	(10	)		$	(57	)
	The discount rate used to determine the actuarial present value of projected postretirement benefit obligations was 4.90% in 2013, 3.95% in 2012 and 5.25% in 2011. The estimated prior service credit that will be amortized from accumulated other comprehensive income into net periodic benefit cost in 2014 is $21,000. The liability for the postretirement benefits included in accrued expenses and other liabilities was $1.1 million at December 31, 2013 and $1.5 million at December 31, 2012.
	The actual health care trend used to measure the accumulated postretirement benefit obligation in 2013 for plan participants below age 65 and for plan participants over age 65 was 2.7% and -14.5%, respectively. In 2012, the rate for plan participants below age 65 and for plan participants over age 65 was 3.0% and -14.7%, respectively. The rates to be used in 2014 through 2018 are expected to be in the range of 7.3% to 6.5% and to decline gradually thereafter to 5.3%. Assumed health care trend rates may have a significant effect on the amounts reported for the postretirement benefit plan. A 1% change in assumed health care cost trend rates would have the following effects:
		1% Increase				1% Decrease
		(In Thousands)
	Effect on total service and interest cost components of net periodic postretirement benefit costs	$	26			$	(20	)
	Effect on the accumulated postretirement benefit obligation	215				(171		)
	401(k) Plans
	The Company administers two 401(k) plans, both of which are qualified, tax-exempt profit-sharing plans with a salary deferral feature under Section 401(k) of the Internal Revenue Code. Each employee reaching the age of 21 and having completed 1,000 hours of service in a plan year is eligible to participate in a plan by making voluntary contributions, subject to certain limits based on federal tax laws. In one plan, the Company contributes an amount equal to 5% of the compensation of eligible employees, but does not match employee contributions to the plan. Participants are vested in employer contributions after three years of service. In the other plan, the Company makes a matching contribution of the amount contributed by eligible employees, up to 4% of the employee's yearly compensation. Contributions to both plans are subject to certain limits based on federal tax laws. Expenses associated with the plans were $2.0 million in 2013, $1.8 million in 2012 and $1.0 million in 2011.
	Nonqualified Deferred Compensation Plan
	The Company also maintains a Nonqualified Deferred Compensation Plan (the "Nonqualified Plan") under which certain participants may contribute the amounts they are precluded from contributing to the Company's 401(k) plans because of the qualified plan limitations, and additional compensation deferrals that may be advantageous for personal income tax or other planning reasons. Expenses associated with the Nonqualified Plan in 2013, 2012 and 2011 were $0.5 million, $0.5 million and $0 million, respectively. Accrued liabilities associated with the Nonqualified Plan in 2013, 2012 and 2011 were $0.4 million, $0.5 million and $0 million, respectively.
	Supplemental Executive Retirement Agreements
	The Company acquired two Supplemental Executive Retirement Plans ("the SERPs") as part of its acquisitions of BankRI and First Ipswich. The Company maintains the SERPs for certain senior executives under which participants are entitled to an annual retirement benefit. As of December 31, 2013, there are 13 participants in the SERPs. The Company funded a Rabbi Trust to provide a partial funding source for the Company's liabilities under the SERPs. The Company records annual amounts related to the SERPs based on an actuarial calculation. Actuarial gains and losses are reflected immediately in the statement of imcome.
	Total expenses for benefits payable under the SERPs for the years ended December 31, 2013, and 2012 were $0.6 million, $0.4 million, respectively. Aggregate benefits payable included in accrued expenses and other liabilities at December 31, 2013 and 2012 were $10.1 million and $10.7 million, respectively.
	The nominal discount rate used to determine the actuarial present value of projected benefits under the agreements was 5% and 4.25% in the year 2013 and 2012, respectively.
	Employee Stock Ownership Plan
	Brookline Bank established an Employee Stock Ownership Plan ("ESOP") on November 1, 1997. The Company's ESOP loan to Brookline Bank to purchase 546,986 shares of Company common stock is payable in quarterly installments over 30 years, bears interest at 8.50% per annum, matures December 31, 2021 and can be prepaid without penalty. Loans are repaid to the Company in the form of cash contributions from Brookline Bank, subject to federal tax law limits. The outstanding balance of the loan at December 31, 2013 and 2012, which was $2.3 million and $2.6 million, respectively, is eliminated in consolidation.
	Shares of common stock used as collateral to secure the loan are released and available for allocation to eligible employees as the principal and interest on the loan is paid. Employees vest in their ESOP account at a rate of 20% annually commencing in the year of completion of three years of credited service or immediately if service is terminated due to death, retirement, disability or change in control.
	Dividends on released shares are credited to the participants' ESOP accounts. Dividends on unallocated shares of common stock are generally applied towards payment of the loan. ESOP shares committed to be released are considered outstanding in determining earnings per share.
	At December 31, 2013 and 2012, the ESOP held 291,666 and 333,918 unallocated shares, respectively at an aggregate cost of $1.5 million and $1.7 million, respectively. The market value of such shares at December 31, 2013 and 2012 was $2.8 million and $2.8 million, respectively. Compensation and employee benefits expense related to the ESOP was $0.4 million in 2013, $0.4 million in 2012 and $0.4 million in 2011 based on the commitment to release to eligible employees 42,252 shares in 2013, 44,292 shares in 2012 and 46,207 shares in 2011.
	Recognition and Retention Plans
	On April 20, 2011, the stockholders of the Company approved the 2011 Restricted Stock Award Plan (the "2011 RSA"). The purpose of the 2011 RSA is to promote the long-term financial success of the Company and its subsidiaries by providing a means to attract, retain and reward individuals who contribute to such success and to further align their interests with those of the Company's stockholders. The maximum number of shares of the Company's common stock that may be awarded is 500,000.
	The Company awarded 138,500 and 166,941 shares of common stock under the 2011 RSA in 2013 and 2012, respectively. Of the awarded shares, 50% vest over three years with one-third of such shares vesting at each of the first, second and third anniversary dates of the awards. The remaining 50% of each award will vest three years after the award date based on the level of the Company's achievement of identified performance targets in comparison to the level of achievement of such identified performance targets by a defined peer group comprised of 22 financial institutions. The specific performance measure targets relate to return on assets, return on equity, asset quality and total return to stockholders (share price appreciation from date of award plus dividends paid as a percent of the Company's common stock share price on the date of award). If a participant leaves the Company prior to the third anniversary date of an award, any unvested shares will be forfeited. Dividends declared with respect to shares awarded will be held by the Company and paid to the participant only when the shares vest.
	The Company also has an active recognition and retention plan, titled the 2003 Recognition and Retention Plan (the "2003 RRP"), with 1,250,000 authorized shares. A prior plan, the 1999 Recognition and Retention Plan (the "1999 RRP" and collectively with the 2003 RRP, the "RRPs"), with 546,986 authorized shares, was terminated on April 19, 2009. Under both of the RRPs, shares of the Company's common stock were reserved for issuance as restricted stock awards to officers, employees and non-employee directors of the Company. Shares issued upon vesting may be either authorized but unissued shares or reacquired shares held by the Company as treasury shares. Any shares not issued because vesting requirements are not met will again be available for issuance under the plans. All shares awarded under the 1999 RRP vested on or before April 19, 2009. As of that date, no shares remained available for award under that plan. As of December 31, 2013, 11,599 shares were available for award under the 2003 RRP.
	Total expense for the RSA and RRP plans was $1.2 million in 2013, $0.8 million in 2012 and $0.4 million in 2011. The expense to be recognized for unvested shares at December 31, 2013 will be $1.5 million in 2014. Dividends paid on unvested RRP shares, which are recognized as compensation expense, were $30,000 in 2013, $11,000 in 2012 and $12,000 in 2011.
	No dividend equivalent rights were paid to holders of unexercised vested options in 2013, 2012, or 2011.
	Stock Option Plans
	The Company has an active stock option plan, the "2003 Option Plan." A prior plan, the "1999 Option Plan," was terminated on April 19, 2009. Under both stock option plans, shares of the Company's common stock were reserved for issuance to directors, employees and non-employee directors of the Company. Shares issued upon the exercise of a stock option may be either authorized but unissued shares or reacquired shares held by the Company as treasury shares. Any shares subject to an award which expire or are terminated unexercised will again be available for issuance under the plans.
	The exercise price of options awarded is the fair market value of the common stock of the Company on the date the award is made. Certain of the options include a reload feature whereby an optionee exercising an option by delivery of shares of common stock would automatically be granted an additional option at the fair market value of stock when such additional option is granted equal to the number of shares so delivered. If an individual to whom a stock option was granted ceases to maintain continuous service by reason of normal retirement, death or disability, or following a change in control, all options and rights granted and not fully exercisable become exercisable in full upon the happening of such an event and shall remain exercisable for a period ranging from three months to five years.
	In 2011, 5,000 options were awarded under the 2003 Option Plan, all of which vested throughout 2012.
	No options were granted in 2013 or 2012. At December 31, 2013, 2,265,155 options were available for award under the Company's 2003 Option Plan.
	Total expense for the stock option plans amounted to $10,000 in 2012 and $47,000 in 2011. In accordance with the terms of the Plans, no dividend equivalent rights were paid to holders of unexercised vested options in 2013, 2012 or 2011.
	Activity under the option plans was as follows:
		Options			Weighted				Aggregate				Weighted
		Outstanding			Average				Intrinsic				Average
					Exercise Price				Value				Contractual
					Per Share								Term (In Years)
		(Dollars in Thousands, Except Per Share Amounts)
	Employee Stock Options:
	Outstanding at December 31, 2010	1,128,345			$	14.08
	Granted	5,000			8.29
	Exercised	—			—
	Forfeited / Canceled	(42,500	)		14.67
	Outstanding at December 31, 2011	1,090,845			14.08
	Granted	—			—
	Exercised	—			—
Forfeited / Canceled	(15,000	)		14.95
Outstanding at December 31, 2012	1,075,845			14.95
Granted	—			—
Exercised	—			—
Forfeited / Canceled	(841,000	)		14.95
Outstanding at December 31, 2013	234,845			$	10.43			$	—			5.7
Exercisable at December 31, 2013	234,845			$	10.43			$	—			5.7
To calculate the weighted average data presented in this note and the compensation expense presented in the accompanying financial statements, the fair value of each stock option award was estimated on the date of grant using the Black-Scholes option pricing model with the following valuation assumptions:
	Year Ended December 31,
	2011
Dividend yield	4.3	%
Expected volatility	34.38	%
Risk-free interest rate	1.85	%
Expected life of options	7

Fair_Value_of_Financial_Instru

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2013
Fair Value Disclosures [Abstract]	'
Fair Value of Financial Instruments	'
	Fair Value of Financial Instruments
	A description of the valuation methodologies used for assets and liabilities measured at fair value on a recurring and non-recurring basis, as well as the general classification of such instruments pursuant to the valuation hierarchy, is set forth below. There were no changes in the valuation techniques used during 2013.
	Assets and Liabilities Recorded at Fair Value on a Recurring Basis
	Assets and liabilities measured at fair value on a recurring basis at December 31, 2013 and 2012 are as follows:
		Carrying Value as of December 31, 2013
		Level 1			Level 2			Level 3				Total
		(In Thousands)
	Assets:
	Securities available-for-sale:
	GSEs	$	—		$	12,180		$	—			$	12,180
	Municipal obligations	—			1,086			—				1,086
	Auction-rate municipal obligations	—			—			1,775				1,775
	Corporate debt obligations	—			28,224			—				28,224
	Trust preferred securities and pools	—			1,210			—				1,210
	GSE CMOs	—			243,644			—				243,644
	GSE MBSs	—			199,401			—				199,401
	Private-label CMOs	—			3,355			—				3,355
	SBA commercial loan asset-backed securities	—			243			—				243
	Marketable equity securities	1,310			—			—				1,310
	Total securities available-for-sale	$	1,310		$	489,343		$	1,775			$	492,428
	Interest-rate swaps	$	—		$	825		$	—			$	825
	Liabilities:
	Interest-rate swaps	$	—		$	856		$	—			$	856
		Carrying Value as of December 31, 2012
		Level 1			Level 2			Level 3				Total
		(In Thousands)
	Assets:
	Investment securities available-for-sale:
	GSEs	$	—		$	69,809		$	—			$	69,809
	Municipal obligations	—			1,101			—				1,101
	Auction-rate municipal obligations	—			—			1,976				1,976
	Corporate debt obligations	—			10,685			—				10,685
	Trust preferred securities and pools	—			1,578			941				2,519
	GSE CMOs	—			217,001			—				217,001
	GSE MBSs	—			169,648			—				169,648
	Private-label CMOs	—			6,866			—				6,866
	SBA commercial loan asset-backed securities	—			381			—				381
	Marketable equity securities	1,337			—			—				1,337
	Total investment securities available-for-sale	$	1,337		$	477,069		$	2,917			$	481,323
	Interest-rate swaps	$	—		$	1,317		$	—			$	1,317
	Liabilities:
	Interest-rate swaps	$	—		$	1,380		$	—			$	1,380
	Assets and Liabilities Recorded at Fair Value on a Non-Recurring Basis
	Assets and liabilities measured at fair value on a non-recurring basis at December 31, 2013 and 2012 are summarized below:
		Carrying Value as of December 31, 2013
		Level 1			Level 2			Level 3				Total
		(In Thousands)
	Assets measured at fair value on a non-recurring basis:
	Collateral-dependent impaired loans and leases	$	—		$	—		$	12,099			$	12,099
	Other real estate owned	—			—			577				577
	Repossessed assets	—			1,001			—				1,001
		$	—		$	1,001		$	12,676			$	13,677
		Carrying Value as of December 31, 2012
		Level 1			Level 2			Level 3				Total
		(In Thousands)
	Assets measured at fair value on a non-recurring basis:
	Collateral-dependent impaired loans and leases	$	—		$	36,749		$	—			$	36,749
	Other real estate owned	—			903			—				903
	Repossessed assets	—			588			—				588
		$	—		$	38,240		$	—			$	38,240
	Investment Securities Available-for-Sale
	The fair value of investment securities is based principally on market prices and dealer quotes received from third-party, nationally-recognized pricing services for identical investment securities such as U.S. Treasury and agency securities that are included in Level 1. These prices are validated by comparing the primary pricing source with an alternative pricing source when available. When quoted market prices for identical securities are unavailable, the Company uses market prices provided by independent pricing services based on recent trading activity and other observable information, including but not limited to market interest-rate curves, referenced credit spreads and estimated prepayment speeds where applicable. These investments include certain U.S. and government agency debt securities, municipal and corporate debt securities, and GSE residential MBSs and CMOs, all of which are included in Level 2. Certain fair values are estimated using pricing models (such as trust preferred securities and auction-rate municipal securities) and are included in Level 3.
	Interest-Rate Swaps
The fair values for the interest-rate swap assets and liabilities represent a Level 2 valuation and are based on settlement values adjusted for credit risks associated with the counterparties and the Company. Credit risk adjustments consider factors such as the likelihood of default by the Company and its counterparties, its net exposures and remaining contractual life. To date, the Company has not realized any losses due to a counterparty's inability to pay any net uncollateralized position. The change in value of interest-rate swap assets and liabilities attributable to credit risk was not significant during the reported periods. Refer also to Note 16, "Derivatives and Hedging Activities."
Collateral-Dependent Impaired Loans and Leases
For nonperforming loans and leases where the credit quality of the borrower has deteriorated significantly, fair values of the underlying collateral were estimated using purchase and sales agreements (Level 2), or comparable sales or recent appraisals (Level 3), adjusted for selling costs and other expenses.
Other Real Estate Owned
The Company records other real estate owned at the lower of cost or fair value. In estimating fair value, the Company utilizes purchase and sales agreements (Level 2) or comparable sales, recent appraisals or cash flows discounted at an interest rate commensurate with the risk associated with these cash flows (Level 3), adjusted for selling costs and other expenses.
Repossessed Assets
Repossessed vehicles and equipment are carried at estimated fair value less costs to sell based on auction pricing (Level 2).
The table below presents quantitative information about significant unobservable inputs (Level 3) for assets measured at fair value on a recurring basis at December 31, 2013.
	Fair Value			Valuation Technique		Unobservable Input	Range		Weighted
									Average
									Yields
	(Dollars in Thousands)
Auction-rate municipal obligations	$	1,775		Discounted cash flow		Discount rate	0-5%		4	%
Collateral-dependent impaired loans and leases	$	12,099		Appraisal of collateral (1)
Other real estate owned	$	577		Appraisal of collateral (1)
(1) For impaired loans deemed collateral dependent, where impairment is measured using the fair value of the collateral, the Bank will either obtain a new appraisal or use another available source of collateral assessment to determine a reasonable estimate of the fair value of the collateral.
The reconciliation of all assets measured at fair value on a recurring basis using significant unobservable inputs (Level 3) is as follows for the periods indicated:
	Year Ended December 31,
	2013			2012
	(In Thousands)
Investment securities available-for-sale, beginning of year	$	2,917		$	3,208
Acquired, BankRI	—			184
Principal paydowns and other	(1,150		)	(836		)
Total unrealized gains included in other comprehensive income	8			361
Investment securities available-for-sale, end of year	$	1,775		$	2,917
There were no transfers between levels for assets and liabilities recorded at fair value on a recurring basis during 2013 or 2012.
Summary of Estimated Fair Values of Financial Instruments
The following table presents the carrying amount, estimated fair value, and placement in the fair value hierarchy of the Company's financial instruments as of December 31, 2013 and 2012. This table excludes financial instruments for which the carrying amount approximates fair value. Financial assets for which the fair value approximates carrying value include cash and cash equivalents, FHLBB and FRB stock and accrued interest receivable. Financial liabilities for which the fair value approximates carrying value include non-maturity deposits, short-term borrowings and accrued interest payable.
							Fair Value Measurements
	Carrying			Estimated			Level 1				Level 2		Level 3
	Value			Fair Value			Inputs				Inputs		Inputs
	(In Thousands)
31-Dec-13
Financial assets:
Investment securities held-to-maturity	$	500		$	500		$	—			$	—	$	500
Loans held for sale	13,372			13,372			—				13,372		—
Loans and leases, net	4,313,992			4,552,556			—				—		4,552,556
Financial liabilities:
Certificates of deposit	934,668			938,703			—				938,703		—
Borrowed funds	812,555			815,910			—				815,910		—
31-Dec-12
Financial assets:
Investment securities held-to-maturity	$	500		$	502		$	—			$	—	$	502
Loans held for sale	3,233			3,233			—				3,233		—
Loans and leases, net	4,134,560			4,193,678			—				—		4,193,678
Financial liabilities:
Certificates of deposit	1,010,941			1,019,916			—				1,019,916		—
Borrowed funds	853,969			872,046			—				872,046		—
Investment Securities Held-to-Maturity
The fair value of securities held-to-maturity are estimated using pricing models or are based on comparisons to market prices of similar securities and considered to be Level 3.
Loans Held for Sale
Fair value is measured using quoted markets prices when available. These assets are typically categorized as Level 1. If quoted market prices are not available, comparable market values or discounted cash flow analysis may be utilized. These assets are typically categorized as Level 2.
Loans and Leases
The fair value of performing loans and leases was estimated by segregating the portfolio into its primary loan and lease categories—commercial real estate mortgage, multi-family mortgage, construction, commercial, equipment financing, condominium association, indirect automobile, residential mortgage, home equity and other consumer. These categories were further disaggregated based upon significant financial characteristics such as type of interest rate (fixed, variable) and payment status (current, past-due). The Company then discounted the contractual cash flows for each loan category using interest rates currently being offered for loans with similar terms to borrowers of similar quality and estimates of future loan prepayments. This method of estimating fair value does not incorporate the exit price concept of fair value.
Deposits
The fair values of deposit liabilities with no stated maturity (demand, NOW, savings and money market savings accounts) are equal to the carrying amounts payable on demand. The fair value of certificates of deposit represents contractual cash flows discounted using interest rates currently offered on deposits with similar characteristics and remaining maturities. The fair value estimates for deposits do not include the benefit that results from the low-cost funding provided by the Company's core deposit relationships (deposit-based intangibles).
Borrowed Funds
The fair value of federal funds purchased is equal to the amount borrowed. The fair value of FHLBB advances and repurchase agreements represents contractual repayments discounted using interest rates currently available for borrowings with similar characteristics and remaining maturities. The fair values reported for retail repurchase agreements are based on the discounted value of contractual cash flows. The discount rates used are representative of approximate rates currently offered on borrowings with similar characteristics and maturities. The fair values reported for subordinated deferrable interest debentures are based on the discounted value of contractual cash flows. The discount rates used are representative of approximate rates currently offered on instruments with similar terms and maturities.

Condensed_Parent_Company_Finan

Condensed Parent Company Financial Statements	12 Months Ended
	Dec. 31, 2013
Condensed Financial Information of Parent Company Only Disclosure [Abstract]	'
Condensed Parent Company Financial Statements	'
	Condensed Parent Company Financial Statements
	Condensed Parent Company Balance Sheets as of December 31, 2013 and 2012 and Statements of Income for the years ended December 31, 2013, 2012 and 2011 follow. The Statement of Stockholders' Equity is not presented below as the parent company's stockholders' equity is that of the consolidated company.
	Balance Sheets
		At December 31,
		2013			2012
		(In Thousands)
	ASSETS
	Cash and due from banks	$	12,438		$	4,547
	Short-term investments	33			33
	Total cash and cash equivalents	12,471			4,580
	Restricted equity securities	100			100
	Loan to Brookline Bank ESOP	2,252			2,502
	Premises and equipment, net	11,850			8,202
	Deferred tax asset	—			1,879
	Investment in subsidiaries, at equity	575,375			592,961
	Goodwill	35,267			35,267
	Other assets	6,185			1,893
	Total assets	$	643,500		$	647,384
	LIABILITIES AND STOCKHOLDERS' EQUITY
	Demand checking accounts	$	—		$	41
	Borrowed funds	9,163			12,091
	Deferred tax liability	1,195			—
	Accrued expenses and other liabilities	19,275			23,155
	Total liabilities	29,633			35,287
	Stockholders' equity:
	Common stock	757			757
	Additional paid-in capital	617,538			618,426
	Retained earnings, partially restricted	64,903			53,358
	Accumulated other comprehensive (loss) income	(7,915		)	3,483
	Treasury stock, at cost; 5,171,985 shares and 5,373,733 shares, respectively	(59,826		)	(62,107		)
	Unallocated common stock held by ESOP; 291,666 shares and 333,918 shares, respectively	(1,590		)	(1,820		)
	Total Brookline Bancorp, Inc. stockholders' equity	613,867			612,097
	Total liabilities and stockholders' equity	$	643,500		$	647,384
	Statements of Income
		Year Ended December 31,
		2013			2012			2011
		(In Thousands)
	Interest and dividend income:
	Dividend income from subsidiaries	$	30,000		$	30,000		$	167,003
	Short-term investments	—			—			1
	Loan to Brookline Bank ESOP	205			227			249
	Total interest and dividend income	30,205			30,227			167,253
	Interest expense:
	Borrowed funds and subordinated debt	442			589			91
	Net interest income	29,763			29,638			167,162
	Non-interest expense:
	Compensation and employee benefits	2,305			11,302			—
	Occupancy	16			—			—
	Equipment and data processing	4,263			1,395			—
	Directors' fees	590			580			225
	Franchise taxes	223			175			180
	Professional services	583			2,773			1,758
	Advertising and marketing	6			11			—
	Other	2,386			2,477			229
	Total non-interest expense	10,372			18,713			2,392
	Income before income taxes	19,391			10,925			164,770
	(Credit) provision for income taxes	(4,035		)	(7,050		)	285
	Income before distributions in excess of net income of subsidiaries	23,426			17,975			164,485
	Distributions less than (in excess of) net income of subsidiaries	11,960			19,167			(136,885		)
	Net income	$	35,386		$	37,142		$	27,600
	Statements of Cash Flows
		Year Ended December 31,
		2013			2012			2011
	(In Thousands)
Cash flows from operating activities:
Net income attributable to parent company	$	35,386		$	37,142		$	27,600
Adjustments to reconcile net income to net cash provided from operating activities:
Distributions in excess (less than) of net income of subsidiaries	(11,960		)	(19,167		)	137,227
Other operating activities, net	16,555			(5,617		)	1,202
Net cash provided from operating activities	39,981			12,358			166,029
Cash flows from investing activities:
Acquisitions, net of cash and cash equivalents acquired	—			(89,258		)	(19,729		)
Monies in escrow—Bancorp Rhode Island, Inc. acquisition	—			112,983			(112,983		)
Repayment of ESOP loan by Brookline Bank	250			250			250
Purchase of restricted equity securities	—			(100		)	—
Purchase of premises and equipment	(5,458		)	(8,557		)	—
Net cash provided from (used in) investing activities	(5,208		)	15,318			(132,462		)
Cash flows from financing activities:
(Decrease) increase in demand deposit, NOW, savings and money market accounts	(41		)	41			—
Payment of dividends on common stock	(23,841		)	(23,777		)	(19,964		)
Repayment of subordinated and other debt	(3,000		)	—			(13,985		)
Income tax benefit from vesting of recognition and retention plan shares, exercise of non-incentive stock options, payment of dividend equivalent rights and dividend distribution on allocated ESOP shares	—			—			79
Net cash used in financing activities	(26,882		)	(23,736		)	(33,870		)
Net increase (decrease) in cash and cash equivalents	7,891			3,940			(303		)
Cash and cash equivalents at beginning of year	4,580			640			943
Cash and cash equivalents at end of year	$	12,471		$	4,580		$	640
Supplemental disclosures of cash flow information:
Cash paid during the year for:
Interest on subordinated debt	$	480		$	795		$	—
Income taxes	19,137			16,981			—
Acquisition of Bancorp Rhode Island:
Fair value of assets acquired, net of cash and cash equivalents acquired	$	—		$	1,571,817		$	—
Fair value of liabilities assumed	—			1,481,535			—
Acquisition of First Ipswich Bancorp:
Fair value of assets acquired, net of cash and cash equivalents acquired	$	—		$	—		$	246,186
Fair value of liabilities assumed	—			—			251,978

Quarterly_Results_of_Operation

Quarterly Results of Operations (Unaudited)	12 Months Ended
	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]	'
Quarterly Results of Operations (Unaudited)	'
	Quarterly Results of Operations (Unaudited)
		2013 Quarters
		Fourth			Third			Second			First
		(Dollars in Thousands Except Per Share Data)
	Interest and dividend income	$	51,049		$	50,823		$	52,900		$	51,612
	Interest expense	7,275			7,411			7,537			7,943
	Net interest income	43,774			43,412			45,363			43,669
	Provision for credit losses	3,887			2,748			2,439			1,855
	Net interest income after provision for credit losses	39,887			40,664			42,924			41,814
	Loss on investment in affordable housing projects	(318		)	(558		)	(624		)	(312		)
	Gain on sales of securities, net	397			—			—			—
	Other non-interest income	3,828			4,011			3,762			3,639
	Amortization of identified intangible assets	(1,127		)	(1,154		)	(1,177		)	(1,165		)
	Other non-interest expense	(30,193		)	(28,399		)	(29,638		)	(29,607		)
	Income before income taxes	12,474			14,564			15,247			14,369
	Provision for income taxes	4,325			4,645			5,382			5,129
	Net income	8,149			9,919			9,865			9,240
	Less net income attributable to noncontrolling interest in subsidiary	495			490			375			427
	Net income attributable to Brookline Bancorp, Inc.	$	7,654		$	9,429		$	9,490		$	8,813
	Earnings per share:
	Basic	$	0.11		$	0.14		$	0.14		$	0.13
	Diluted	0.11			0.13			0.14			0.13
	Average common shares outstanding:
	Basic	69,862,175			69,830,953			69,774,703			69,762,784
	Diluted	69,951,683			69,913,765			69,833,541			69,830,630
	Common stock price:
	High	$	9.58		$	10.08		$	9.14		$	9.39
	Low	8.72			8.81			8.23			8.66
	Dividends per share	$	0.085		$	0.085		$	0.085		$	0.085
		2012 Quarters
		Fourth			Third			Second			First
		(Dollars in Thousands Except Per Share Data)
	Interest income	$	52,976		$	55,394		$	51,839		$	52,991
	Interest expense	8,412			8,983			9,080			9,357
	Net interest income	44,564			46,411			42,759			43,634
	Provision for credit losses	3,101			2,862			6,678			3,247
	Net interest income after provision for credit losses	41,463			43,549			36,081			40,387
	Gain on sales of securities, net	129			—			797			—
	Gain on sales of loans and leases	1,898			—			—			—
	Loss from investments in affordable housing projects	(239		)	(73		)	(244		)	(138		)
	Other non-interest income	4,716			3,858			4,168			3,733
	Amortization of identified intangible assets	(1,797		)	(1,271		)	(1,271		)	(1,283		)
	Other non-interest expense	(27,072		)	(29,165		)	(27,350		)	(31,166		)
	Income before income taxes	19,098			16,898			12,181			11,533
	Provision for income taxes	6,868			5,176			4,398			4,899
	Net income	12,230			11,722			7,783			6,634
	Less net income attributable to noncontrolling interest in subsidiary	367			321			254			285
	Net income attributable to Brookline Bancorp, Inc.	$	11,863		$	11,401		$	7,529		$	6,349
	Earnings per share:
	Basic	$	0.17		$	0.16		$	0.11		$	0.09
	Diluted	0.17			0.16			0.11			0.09
	Average common shares outstanding:
	Basic	69,742,225			69,716,283			69,677,656			69,664,619
	Diluted	69,799,324			69,754,473			69,715,890			69,665,873
	Common stock price:
	High	$	8.9		$	9.25		$	9.49		$	9.78
	Low	7.54			8.13			8.46			8.37
	Dividends per share	$	0.085		$	0.085		$	0.085		$	0.085

Basis_of_Presentation_Policies

Basis of Presentation (Policies)	12 Months Ended
	Dec. 31, 2013
Accounting Policies	'
Basis of Financial Statement Presentation	'
	Basis of Financial Statement Presentation
	The Company's consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles ("GAAP") as set forth by the Financial Accounting Standards Board ("FASB") in its Accounting Standards Codification and through the rules and interpretive releases of the Securities and Exchange Commission ("SEC") under the authority of federal securities laws.
	The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All significant intercompany transactions and balances are eliminated in consolidation.
	In preparing these consolidated financial statements, management is required to make significant estimates and assumptions that affect the reported amounts of assets, liabilities, income, expenses and disclosure of contingent assets and liabilities. Actual results could differ from those estimates based upon changing conditions, including economic conditions and future events. Material estimates that are particularly susceptible to significant change in the near-term include the determination of the allowance for loan and lease losses, the determination of fair market values of assets and liabilities, including acquired loans, the review of goodwill and intangibles for impairment and the review of deferred tax assets for valuation allowance.
	The judgments used by management in applying these critical accounting policies may be affected by a further and prolonged deterioration in the economic environment, which may result in changes to future financial results. For example, subsequent evaluations of the loan and lease portfolio, in light of the factors then prevailing, may result in significant changes in the allowance for loan and lease losses in future periods, and the inability to collect outstanding principal may result in increased loan and lease losses.
Reclassification	'
	Reclassification
	Certain previously reported amounts have been reclassified to conform to the current year's presentation.
Cash and Cash Equivalents	'
	Cash and Cash Equivalents
	For purposes of reporting asset balances and cash flows, cash and cash equivalents includes cash on hand and due from banks (including cash items in process of clearing), interest-bearing deposits with banks, federal funds sold, money market mutual funds and other short-term investments with original maturities of three months or less.
Investment Securities	'
	Investment Securities
	Investment securities, other than those reported as short-term investments, are classified at the time of purchase as "available for sale," "held to maturity," or "trading." Classification is periodically re-evaluated for consistency with the Company's goals and objectives. Equity investments in the Federal Home Loan Bank of Boston ("FHLBB") and the Federal Reserve Bank of Boston are discussed in more detail in Note 5, "Restricted Equity Securities."
	Investment Securities Available-for-Sale and Held-to-Maturity
	Securities for which the Company has the positive intent and ability to hold to maturity are classified as held-to-maturity and carried at amortized cost. Those securities held for indefinite periods of time but not necessarily to maturity are classified as available-for-sale. Securities held for indefinite periods of time include securities that management intends to use as part of its asset/liability, liquidity, and/or capital management strategies and may be sold in response to changes in interest rates, maturities, asset/liability mix, liquidity needs, regulatory capital needs or other business factors. Securities available-for-sale are carried at estimated fair value, primarily obtained from a third-party pricing service, with unrealized gains and losses reported on an after-tax basis in stockholders' equity as accumulated other comprehensive income or loss. As of December 31, 2013 and 2012, the Company did not make any adjustments to the prices provided by the third-party pricing service.
	Security transactions are recorded on the trade date. Realized gains and losses are determined using the specific identification method and are recorded in non-interest income. Interest and dividends on securities are recorded using the accrual method. Premiums and discounts on securities are amortized or accreted into interest income using the level-yield method over the remaining period to contractual maturity, adjusted for the effect of actual prepayments in the case of mortgage-backed securities ("MBSs") and collateralized mortgage obligations ("CMOs"). These estimates of prepayment assumptions are made based upon the actual performance of the underlying security, current interest rates, the general market consensus regarding changes in mortgage interest rates, the contractual repayment terms of the underlying loans, the priority rights of the investors to the cash flows from the mortgage securities and other economic conditions. When differences arise between anticipated prepayments and actual prepayments, the effective yield is recalculated to reflect actual payments to date and anticipated future payments. Unamortized premium or discount is adjusted to the amount that would have existed had the new effective yield been applied since purchase, with a corresponding charge or credit to interest income.
	Management evaluates securities for other-than-temporary impairment ("OTTI") on a periodic basis. Factors considered in determining whether an impairment is other-than-temporary include: (1) the length of time and the extent to which the fair value has been less than cost, (2) the financial condition and near-term prospects of the issuer and (3) the intent and ability of the Company to hold the investment for a period of time sufficient to allow for any anticipated recovery in fair value. The Company records an other-than-temporary loss in an amount equal to the entire difference between the fair value and amortized cost if (1) the Company intends to sell an impaired security, (2) it is more likely than not that the Company will be required to sell the security before its amortized costs or (3) for debt securities, the present value of expected future cash flows is not sufficient to recover the entire amortized cost basis. If a security is determined to be other-than-temporarily impaired but the Company does not intend to sell the security, only the credit portion of the estimated loss is recognized in earnings, with the other portion of the loss recognized in other comprehensive income.
	Restricted Securities
	The Company owns investments in the stock of the FHLBB, the Federal Reserve Bank of Boston and a small amount of other restricted securities. No ready market exists for these stocks, and they have no quoted market values. The Banks, as members of the FHLBB, are required to maintain investments in the capital stock of the FHLBB equal to their membership base investments plus an activity-based investment determined according to the Banks' level of outstanding FHLBB advances. Federal Reserve Bank of Boston stock was purchased at par and is redeemable at par.
Loans	'
	Loans
	Originated Loans
	Loans the Company originates for the portfolio, and for which it has the intent and ability to hold to maturity, are reported at amortized cost, inclusive of deferred loan origination fees and expenses, less unadvanced funds due borrowers on loans and the allowance for loan and lease losses.
	Interest income on loans and leases originated for the portfolio is accrued on unpaid principal balances as earned. Loan origination fees and direct loan origination costs are deferred, and the net fee or cost is recognized in interest income using the interest method. Deferred loan origination costs include payments to dealers originating indirect automobile loans. The difference between the rate charged by a dealer to originate an indirect automobile loan and the "buy rate," or the rate earned by the Company, is referred to as the "spread." The computed dollar value of the spread paid to a dealer is amortized as a charge to income over the life of the loan on a level-yield basis. Deferred amounts are recognized for fixed-rate loans over the contractual life of the loans and for adjustable-rate loans over the period of time required to adjust the contractual interest rate to a yield approximating a market rate at the origination date. If a loan is prepaid, the unamortized portion of the loan origination costs, including those indirect-automobile-related costs not subject to rebate from the dealer, is charged to income.
	Loans Held-for-Sale
	Management identifies and designates certain newly originated loans for sale to specific financial institutions, subject to the underwriting criteria of those financial institutions. These loans are held for sale and are carried at the lower of cost or market as determined in the aggregate. Deferred loan fees and costs are included in the determination of the gain or loss on sale.
	Acquired Loans
	Acquired loans that have evidence of deterioration of credit quality since origination and for which it is probable, at acquisition, that the Corporation will be unable to collect all contractually required payments receivable are initially recorded at fair value (as determined by the present value of expected future cash flows) with no valuation allowance. The difference between the undiscounted cash flows expected at acquisition and the recorded fair value of the loan, or the “accretable yield,” is recognized as interest income on a level-yield method over the life of the loan. Contractually required payments for interest and principal that exceed the undiscounted cash flows expected at acquisition, or the “nonaccretable difference,” are not recognized as a yield adjustment or as a loss accrual or a valuation allowance. Increases in expected cash flows subsequent to the initial investment are recognized prospectively through adjustment of the yield on the loan over its remaining life. Decreases in expected cash flows are recognized as impairment. Valuation allowances on these impaired loans reflect only losses incurred after the acquisition (meaning the present value of all cash flows expected at acquisition that ultimately are not to be received).
Non-Performing Loans	'
	Nonperforming Loans
	Nonaccrual Loans
	Accrual of interest on loans generally is discontinued when contractual payment of principal or interest becomes past due 90 days or, if in management's judgment, reasonable doubt exists as to the full timely collection of interest. Exceptions may be made if the loan has matured and is in the process of renewal or is well-secured and in the process of collection. When a loan is placed on nonaccrual status, interest accruals cease and uncollected accrued interest is reversed and charged against current interest income. Interest payments on nonaccrual loans are applied to principal. Loans are returned to accrual status when principal and interest payments are current, full collectability of principal and interest is reasonably assured and a consistent record of at least six consecutive months of performance has been achieved.
	Impaired Loans
	A loan is considered to be impaired when, based on current information and events, it is probable that the Company will be unable to collect all amounts due (both interest and principal) according to the contractual terms of the loan agreement. Smaller-balance, homogeneous loans that are evaluated collectively for impairment, such as indirect automobile, residential, home equity and other consumer loans are specifically excluded from the impaired loan portfolio except where the loan is classified as a troubled debt restructuring. The Company has defined the population of impaired loans to include nonaccrual loans and troubled debt restructured loans.
	The value of an impaired loan is measured based upon the present value of expected future cash flows discounted at the loan's effective interest rate, or the fair value of the collateral if the loan is collateral-dependent and its payment is expected solely based on the underlying collateral. For impaired loans deemed collateral dependent, where impairment is measured using the fair value of the collateral, the Company will either obtain a new appraisal or use another available source of collateral assessment to determine a reasonable estimate of the fair value of the collateral.
	Interest collected on impaired loans is either applied against principal or reported as income according to management's judgment as to the collectability of principal. If management does not consider a loan ultimately collectible within an acceptable time frame, payments are applied as principal to reduce the loan balance. If full collection of the remaining recorded investment should subsequently occur, interest receipts are recorded as interest income on a cash basis.
	Troubled Debt Restructured Loans
	In cases where a borrower experiences financial difficulties and the Company makes certain concessionary modifications to contractual terms, the loan is classified as a troubled debt restructured loan. In determining whether a debtor is experiencing financial difficulties, the Company considers, among other factors, if the debtor is in payment default or is likely to be in payment default in the foreseeable future without the modification, the debtor declared or is in the process of declaring bankruptcy, there is substantial doubt that the debtor will continue as a going concern, the debtor's entity-specific projected cash flows will not be sufficient to service its debt, or the debtor cannot obtain funds from sources other than the existing creditors at market terms for debt with similar risk characteristics.
	Modifications may include interest-rate reductions, short-term (defined as one year or less) changes in payment structure to interest-only payments, short-term extensions of the loan's original contractual term or, less frequently, principal forgiveness, interest capitalization, forbearance and other actions intended to minimize the economic loss and to avoid foreclosure or repossession of collateral. Typically, troubled debt restructurings are placed on nonaccrual status and reported as nonperforming loans. Generally, a nonaccrual loan that is restructured remains on nonaccrual for a period of six months to demonstrate the borrower can meet the restructured terms; however, performance prior to the restructuring, or significant events that coincide with the restructuring, are considered in assessing whether the borrower can meet the new terms and may result in the loan being returned to accrual status at the time of restructuring or after a shorter performance period. If the borrower's ability to meet the revised payment schedule is not reasonably assured, the loan remains classified as a nonaccrual loan.
	Loans restructured at an interest rate equal to or greater than that of a new loan with comparable risk at the time of the loan agreement is modified may be excluded from restructured loan disclosures in years subsequent to the restructuring if they are in compliance with the modified terms.
Allowance for Loan and Lease Losses	'
	Allowance for Loan and Lease Losses
	Additions to the allowance for loan and lease losses are made by charges to the provision for credit losses. Losses on loans and leases are charged off against the allowance when all or a portion of a loan or lease is considered uncollectible. Subsequent recoveries on loans previously charged off, if any, are credited to the allowance when realized
	The allowance for loan and lease losses consists of general, specific and unallocated reserves and reflects management's estimate of probable loan and lease losses inherent in the loan portfolio at the balance sheet date. Management uses a consistent and systematic process and methodology to evaluate the adequacy of the allowance for loan and lease losses on a quarterly basis. The allowance is calculated by loan category, including commercial real estate loans, commercial loans and leases, indirect automobile loans and consumer loans; with each of these categories further segregated into classes. A formula-based credit evaluation approach is applied to each group, coupled with an analysis of certain loans for impairment.
	The process to determine the allowance for loan and lease losses requires management to exercise considerable judgment regarding the risk characteristics of the loan portfolio categories and the effect of relevant internal and external factors. The reasonableness of prior judgments is evaluated on a quarterly basis by comparison of estimated loan and lease losses to loan and lease losses actually incurred. In addition, various regulatory agencies, as an integral part of their examination process, periodically review the Company's allowance for loan and lease losses. Such agencies may require the Company to change the allowance based on their judgments of information available to them at the time of their examination.
	General Allowance
	The general allowance related to loans collectively evaluated for impairment is determined using a formula-based approach utilizing the risk ratings of individual credits and loss factors derived from historic portfolio loss rates. Other relevant qualitative factors include, but are not limited to, historic levels and trends in loan charge-offs and recoveries; past-due loans; risk-rated loans; classified loans and impaired loans; the pace of loan growth; underwriting policies and adherence to such policies; changes in credit concentration; the experience of lending personnel and management; trends in the economy and employment; business conditions; industry conditions; and political, legislative and regulatory changes. The general allowance related to the acquired loans collectively evaluated for impairment are determined based upon the degree, if any, of deterioration in the pooled loans subsequent to acquisition. The qualitative factors used in the determination are the same as those used for originated loans.
	Specific Allowance
	Specific valuation allowances are established for impaired originated loans with book values greater than the discounted present value of expected future cash flows or, in the case of collateral-dependent impaired loans, for any excess of a loan's book balance and the fair value of its underlying collateral. Specific valuation allowances are established for acquired loans with deterioration in the discounted present value of expected further cash flows since acquisitions or, in the case of collateral dependent impaired loans, for any increase in the excess of a loan's book balance greater than the fair value of its underlying collateral. A specific valuation allowance for losses on troubled debt restructured loans is determined by comparing the net carrying amount of the troubled debt restructured loan with the restructured loan's cash flows discounted at the original effective rate. Impaired loans are reviewed quarterly with adjustments made to the calculated reserve as deemed necessary.
	Unallocated Allowance
	Determination of the unallocated portion of the allowance is a subjective process. Management believes the unallocated allowance is an important component of the total allowance because it addresses the probable inherent risk of loss that exists in that part of the Company's loan portfolio with repayment terms that extend over many years. It also helps to minimize the risk related to the margin of imprecision inherent in the estimation of the allocated components of the allowance. The Company has not allocated the unallocated portion of the allowance to the various loan categories and classes because such an allocation would imply a degree of precision that does not exist.
	Liability for Unfunded Commitments
	In the ordinary course of business, the Company enters into commitments to extend credit, commercial letters of credit, and standby letters of credit. Such financial instruments are recorded in the financial statements when they become payable. The credit risk associated with these commitments is evaluated in a manner similar to the allowance for loan losses.
Premises and Equipment	'
	Premises and Equipment
	Premises and equipment are carried at cost less accumulated depreciation and amortization, except for land which is carried at cost. Premises and equipment are depreciated using the straight-line method over the estimated useful life of the assets. Leasehold improvements are amortized using the straight-line method over the shorter of the lease term or the estimated useful life of the improvements.
	Costs related to internal-use software development projects that provide significant new functionality are capitalized. Internal-use software is software acquired or modified solely to meet the Company's needs and for which there is no plan to market the software externally. Direct and indirect costs associated with the application development stage of internal use software are capitalized until such time that the software is substantially complete and ready for its intended use. Capitalized costs are amortized on a straight-line basis over the remaining estimated life of the software. Computer software and development costs incurred in the preliminary project stage, as well as training and maintenance costs, are expensed as incurred.
Bank-Owned Life Insurance	'
	Bank-Owned Life Insurance
	The Company acquired bank-owned life insurance ("BOLI") plans as part of its acquisitions of First Ipswich and BankRI. BOLI represents life insurance on the lives of certain current and former employees who have provided positive consent allowing their employer to be the beneficiary of such policies. BankRI and First Ipswich are the beneficiaries of their respective policies. BankRI and First Ipswich utilize BOLI as tax-efficient financing for their benefit obligations to their employees, including their retirement obligations and Supplemental Executive Retirement Plans ("SERPs").
	Since BankRI and First Ipswich are the primary beneficiaries of their respective insurance policies, increases in the cash value of the policies, as well as insurance proceeds received, are recorded in non-interest income and are not subject to income taxes. BOLI is recorded at the cash value of the policies, less any applicable cash surrender charges, and is reflected as an asset in the accompanying consolidated balance sheets. The Company reviews the financial strength of the insurance carriers prior to the purchase of BOLI to ensure minimum credit ratings of at least investment grade. The financial strength of the carriers is reviewed at least annually and BOLI with any individual carrier is limited to 10% of capital
Goodwill and Other Acquisition-Related Intangible Assets	'
	Goodwill and Other Identified Intangible Assets
	Goodwill represents the excess of the cost of an acquisition over the fair value of the net assets acquired. Goodwill is not subject to amortization. Identified intangible assets are assets resulting from acquisitions that are being amortized over their estimated useful lives. The recoverability of goodwill and identified intangible assets is evaluated for impairment at least annually. As part of this evaluation, the Company makes a qualitative assessment of whether it is more likely than not that the fair value of an acquired asset is greater than its carrying amount. Pursuant to FASB Accounting Standards Update ("ASU") 2011-8, adopted in January 2012, if the Company concludes that it is more likely than not that the fair value of an acquired asset is greater than its carrying amount, no further testing is necessary. If, however, the Company concludes that it is more likely than not that the fair value of an acquired asset is less than its carrying value, the Company performs a two-step quantitative impairment test to determine whether the asset is impaired. If impairment is deemed to have occurred, the amount of impairment is charged to expense when identified.
Other Real Estate Owned and Repossessed Assets	'
	Other Real Estate Owned and Repossessed Assets
	OREO consists of property acquired through foreclosure, real estate acquired through acceptance of a deed in lieu of foreclosure and loans determined to be substantively repossessed. Real estate loans that are substantively repossessed include only those loans for which the Company has taken possession of the collateral. OREO and repossessed assets which consist of vehicles and equipment, if any, are recorded initially at estimated fair value less costs to sell, resulting in a new cost basis. The amount by which the recorded investment in the loan exceeds the fair value (net of estimated cost to sell) of the foreclosed or repossessed asset is charged to the allowance for loan and lease losses. Such evaluations are based on an analysis of individual properties/assets as well as a general assessment of current real estate market conditions. Subsequent declines in the fair value of the foreclosed or repossessed asset below the new cost basis are recorded through the use of a valuation allowance. Subsequent increases in the fair value are recorded as reductions in the allowance, but not below zero. Rental revenue received on foreclosed or repossessed assets is included in other non-interest income, whereas operating expenses and changes in the valuation allowance relating to foreclosed and repossessed assets are included in other non-interest expense. Certain costs used to improve such properties are capitalized. Gains and losses from the sale of OREO and repossessed vehicles and equipment are reflected in non-interest expense when realized. Together with nonperforming loans, OREO and repossessed assets comprise nonperforming assets.
Derivatives	'
	Derivatives
	The Company enters into interest rate swap agreements as part of the Company's interest-rate risk management strategy for certain assets and liabilities and not for speculative purposes. Based on the Company's intended use for the interest rate swap at inception, the Company designates the derivative as either an economic hedge of an asset or liability or a hedging instrument subject to the hedge accounting provisions of FASB ASC Topic 815, "Derivatives and Hedging."
	Interest rate swaps designated as economic hedges are recorded at fair value within other assets or liabilities. Changes in the fair value of these derivatives are recorded directly through earnings at each reporting period.
Transfer of Financial Assets	'
	Transfer of Financial Assets
	Transfers of financial assets are accounted for as sales when control over the assets has been surrendered. Control over transferred assets is deemed to be surrendered when (1)the assets have been isolated from the Company, (2)the transferee obtains the right (free of conditions that constrain it from taking advantage of that right) to pledge or exchange the transferred assets, and (3)the Company does not maintain effective control over the transferred assets through an agreement to repurchase them before their maturity.
Securities Sold Under Agreements to Repurchase	'
	Securities Sold under Agreements to Repurchase
	The Company enters into sales of securities under agreements to repurchase with the Banks' commercial customers. These agreements are treated as financings, and the obligations to repurchase securities sold are reflected as a liability in the consolidated balance sheets. Securities pledged as collateral under agreements to repurchase are reflected as assets in the accompanying consolidated balance sheets.
Employee Benefits	'
	Employee Benefits
	Costs related to the Company's 401(k) plans are recognized over the vesting period or charged against current operations in the year made depending on the plan. Costs related to the Company's nonqualified deferred compensation plan, SERPs and postretirement benefits are recognized over the vesting period or the related service periods of the participating employees. Changes in the funded status of postretirement benefits are recognized through comprehensive income in the year in which changes occur.
	Compensation expense for the Employee Stock Ownership Plan ("ESOP") is recorded at an amount equal to the shares allocated by the ESOP multiplied by the average fair market value of the shares during the year. The Company recognizes compensation expense ratably over the year based upon the Company's estimate of the number of shares expected to be allocated by the ESOP. The difference between the average fair market value and the cost of the shares allocated by the ESOP is recorded as an adjustment to additional paid-in capital.
	The fair value of restricted common stock awards and stock option grants is determined as of the grant date and is recorded as compensation expense over the period in which the shares of common stock and stock options vest. Forfeitures are estimated in determining compensation expense.
Fair Value Measurements	'
	Fair Value Measurements
	ASC 820-10, "Fair Value Measurements and Disclosures," defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. A fair value measurement assumes that the transaction to sell the asset or transfer the liability occurs in the principal market for the asset or liability or, in the absence of a principal market, the most advantageous market for the asset or liability. The price in the principal (or most advantageous) market used to measure the fair value of the asset or liability is not adjusted for transaction costs. An orderly transaction is a transaction that assumes exposure to the market for a period prior to the measurement date to allow for marketing activities that are usual and customary for transactions involving such assets and liabilities. It is not a forced transaction. Market participants are buyers and sellers in the principal market that are independent, knowledgeable, able to transact and willing to transact.
	A fair-value hierarchy for valuation inputs that gives the highest priority to quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs are included in ASC 820. The fair value hierarchy is as follows:
	Level 1: Inputs are unadjusted quoted prices in active markets for assets and liabilities identical to those reported at fair value.
	Level 2: Inputs other than quoted prices included within Level 1. Level 2 inputs are observable either directly or indirectly. These inputs might include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (such as interest rates, volatilities, prepayment speeds, credit risks, etc.) or inputs that are derived principally from or corroborated by market data by correlation or other means.
	Level 3: Inputs are unobservable inputs for an asset or liability that reflect an entity's own assumptions about the assumptions that market participants would use in pricing the assets or liabilities. These inputs are used to determine fair value only when observable inputs are not available.
Earnings per Common Share	'
	Earnings per Common Share
	Basic earnings per share ("EPS") is computed by dividing net income by the weighted average number of shares of common stock outstanding for the applicable period, exclusive of unearned ESOP shares and unvested restricted stock. Diluted EPS is calculated after adjusting the denominator of the basic EPS calculation for the effect of all potential dilutive common shares outstanding during the period. The dilutive effects of options and unvested restricted stock awards are computed using the "treasury stock" method, the results of which are not materially different from those calculated using the “two-class” method.
Income Taxes	'
	Income Taxes
	Income taxes are accounted for under the asset and liability method. Under this method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases.
	Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date.
	Tax positions that are more likely than not to be sustained upon a tax examination are recognized in the Company's financial statements to the extent that the benefit is greater than 50% likely of being recognized. Interest resulting from underpayment of income taxes is classified as income tax expense in the first period the interest would begin accruing according to the provision of the relevant tax law. Penalties resulting from underpayment of income taxes are classified as income tax expense in the period for which the Company claims or expects to claim an uncertain tax position or in the period in which the Company's judgment changes regarding an uncertain tax position.
Treasury Stock	'
	Treasury Stock
	Shares repurchased under the Company's share repurchase programs were purchased in open-market transactions and are held as treasury stock. Treasury stock also consists of common stock withheld to satisfy federal, state and local income tax withholding requirements for vested employee restricted stock awards. All treasury stock is held at cost.
Segment Reporting	'
	Segment Reporting
	An operating segment is defined as a component of a business for which separate financial information is available that is evaluated regularly by the chief operating decision-maker in deciding how to allocate resources and evaluate performance. The Company is a bank holding company with subsidiaries engaged in the business of banking and activities closely related to banking. The Company's banking business provided substantially all of its total revenues and pre-tax income in 2013, 2012 and 2011. Therefore, t
Recent Accounting Pronouncements	'
	Recent Accounting Pronouncements
	In February 2013, FASB issued Accounting Standards Update (“ASU”) No. 2013-01, Clarifying the Scope of Disclosures about Offsetting Assets and Liabilities. This ASU clarifies the scope of offsetting disclosure requirements in ASU 2011-11, Balance Sheet (Topic 210): Disclosures about Offsetting Assets and Liabilities. Under ASU 2013-01, the disclosure requirements would apply to derivative instruments accounted for in accordance with ASC 815, including bifurcated embedded derivatives, repurchase agreements and reverse repurchase agreements, and securities borrowing and securities lending arrangements that are either offset on the balance sheet or subject to an enforceable master netting arrangement or similar agreement. Entities with other types of financial assets and financial liabilities subject to a master netting arrangement or similar agreement also are affected because these amendments make them no longer subject to the disclosure requirements in ASU No. 2011-11. Effective January 1, 2013, companies are required to disclose (a) gross amounts of recognized assets and liabilities; (b) gross amounts offset in the statement of financial position; (c) net amounts of assets and liabilities presented in the statement of financial position; (d) gross amount subject to enforceable master netting agreement not offset in the statements of financial position; and (e) net amounts after deducting (d) from (c). The disclosure should be presented in tabular format (unless another format is more appropriate) separately for assets and liabilities. The intent of the new disclosure is to enable users of financial statements to understand the effect of those arrangements on its financial position and to allow investors to better compare financial statements prepared under GAAP with financial statements prepared under International Financial Reporting Standards. As required, the Company added relevant disclosure in Note 16, “Derivatives and Hedging Activities.”
	In February 2013, FASB issued ASU No. 2013-02, Comprehensive Income (Topic 220): Reporting of Amounts Reclassified out of Accumulated Other Comprehensive Income. This ASU states that the amendments do not change the current requirements for reporting net income or other comprehensive income in financial statements. The amendments do, however, require an entity to provide information about the amounts reclassified out of accumulated other comprehensive income by component. In addition, an entity is required to present, either on the face of the statement where net income is presented or in the notes, significant amounts reclassified out of accumulated other comprehensive income by the respective line items of net income, but only if the amount reclassified is required under U.S. GAAP to be reclassified to net income in its entirety in the same reporting period. For other amounts that are not required to be reclassified in their entirety to net income under U.S. GAAP, an entity is required to cross-reference to other disclosures required under U.S. GAAP that provide additional detail about those amounts. The amendments are effective prospectively for reporting periods beginning after December 15, 2012. In response to this ASU, the Company added a new footnote to disclose the amounts reclassified out of accumulated other comprehensive income and the effects on the line items of net income. See Note 15, “Comprehensive Income.”
	In July 2013, FASB issued ASU 2013-10, Inclusion of the Fed Funds Effective Swap Rate (or Overnight Index Swap Rate) as a Benchmark Interest Rate for Hedge Accounting Purposes. This ASU amends ASC 815 to allow entities to use the Fed Funds Effective Swap Rate, in addition to U.S. Treasury rates and LIBOR, as a benchmark interest rate in accounting for fair value and cash flow hedges in the United States. This ASU also eliminates the provision from ASC 815-20-25-6 that prohibits the use of different benchmark rates for similar hedges except in rare and justifiable circumstances. This ASU is effective prospectively for qualifying new hedging relationship entered into on or after July 17, 2013, and for hedging relationship redesignated on or after that day. As of December 31, 2013, the Company did not have any fair value and cash flow hedges. The adoption of ASU No. 2013-10 did not have a material impact on the Company’s financial statements.
	In July 2013, FASB issued ASU No. 2013-11, Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists. This ASU provides guidance on financial statement presentation of unrecognized tax benefits (“UTBs”) when a net operating loss (“NOL”) carryforward, a similar tax loss, or a tax credit carryforward exists. The FASB’s objective in issuing this ASU is to eliminate diversity in practice resulting from a lack of guidance on this topic in current U.S. GAAP. Under this ASU, an entity must present a UTB, or a portion of a UTB, in the financial statements as a reduction to a deferred tax asset (“DTA”) for an NOL carryforward, a similar tax loss, or a tax credit carryforward except when: (a) an NOL carryforward, a similar tax loss, or a tax credit carryforward is not available as of the reporting date under the governing tax law to settle taxes that would result from the disallowance of the tax position; or (b) the entity does not intend to use the DTA for this purpose (provided that the tax law permits a choice). If either of these conditions exists, an entity should present a UTB in the financial statements as a liability and should not net the UTB with a DTA. New recurring disclosures are not required because the ASU does not affect the recognition or measurement of uncertain tax positions under ASC 740. This amendment does not affect the amounts public entities disclose in the tabular reconciliation of the total amounts of UTBs because the tabular reconciliation presents the gross amount of UTBs. This ASU is effective for fiscal years beginning after December 15, 2013, and interim periods within those years. The amendments should be applied to all UTBs that exist as of the effective date. Entities may choose to apply the amendments retrospectively to each prior reporting period presented. As of December 31, 2013, the Company did not have a UTB. The Company will assess the applicability of this ASU after it become effective and as such has not determined the impact, if any, of this ASU.
	In January 2014, the FASB issued ASU 2014-01, Accounting for Investments in Qualified Low-Income Housing Tax Credit (“LIHTC”) program. This ASU provides guidance on accounting for investments by a reporting entity in flow-through limited liability entities. Currently, investments in low-income housing are accounted for either by the effective yield, equity or cost method. This ASU allows for reporting entities to make a policy election on how to account for their investments. This ASU is applied retrospectively effective prospectively for all annual periods presented beginning after December 15, 2014; early adoption is permitted. The Company has not chosen to early adopt ASU No. 2014-01 and will assess the applicability of this ASU after it become effective and as such has not determined the impact, if any, of this ASU.
	In January 2014, the FASB issued ASU 2014-04, Receivables—Troubled Debt Restructurings by Creditors. This ASU provides clarification on when an in substance repossession or foreclosure occurs resulting in the creditor derecognizing the loan and recognizing the collateral. Currently, there is no definition of in substance a repossession or foreclosure and physical possession in the accounting literature. This ASU is applied retrospectively or effective prospectively for all annual periods presented beginning after December 15, 2014; early adoption is permitted. The Company has not chosen to early adopt ASU No. 2014-04 and will assess the applicability of this ASU after it become effective and as such has not determined the impact, if any, of this ASU.

Cash_and_ShortTerm_Investments1

Cash and Short-Term Investments (Tables)	12 Months Ended
	Dec. 31, 2013
Cash, Cash Equivalents, and Short-term Investments [Abstract]	'
Short-term investments	'
	Short-term investments are summarized as follows:
		At December 31,
		2013		2012
		(In Thousands)
	Money market funds	$	10	$	20
	Federal funds sold	55,347		38,636
		$	55,357	$	38,656

Investment_Securities_Tables

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2013
Investments, Debt and Equity Securities [Abstract]	'
Schedule of securities available-for-sale securities	'
	The following tables set forth investment securities available-for-sale and held-to-maturity at the dates indicated:
		At December 31, 2013
		Amortized		Gross		Gross			Estimated
		Cost		Unrealized		Unrealized			Fair Value
				Gains		Losses
		(In Thousands)
	Debt securities:
	GSEs	$	12,138	$	42	$	—		$	12,180
	GSE CMOs	254,331		86		10,773			243,644
	GSE MBSs	202,478		1,852		4,929			199,401
	Private-label CMOs	3,258		115		18			3,355
	SBA commercial loan asset-backed securities	245		—		2			243
	Auction-rate municipal obligations	1,900		—		125			1,775
	Municipal obligations	1,068		18		—			1,086
	Corporate debt obligations	27,751		506		33			28,224
	Trust preferred securities	1,461		—		251			1,210
	Total debt securities	504,630		2,619		16,131			491,118
	Marketable equity securities	1,259		61		10			1,310
	Total investment securities available-for-sale	$	505,889	$	2,680	$	16,141		$	492,428
	Investment securities held-to-maturity	$	500	$	—	$	—		$	500
		At December 31, 2012
		Amortized		Gross		Gross			Estimated
		Cost		Unrealized		Unrealized			Fair Value
				Gains		Losses
		(In Thousands)
	Debt securities:
	GSEs	$	69,504	$	305	$	—		$	69,809
	GSE CMOs	215,670		1,386		55			217,001
	GSE MBSs	165,996		3,704		52			169,648
	Private-label CMOs	6,719		147		—			6,866
	SBA commercial loan asset-backed securities	383		—		2			381
	Auction-rate municipal obligations	2,100		—		124			1,976
	Municipal obligations	1,058		43		—			1,101
	Corporate debt obligations	10,481		204		—			10,685
	Trust preferred securities and pools	2,786		136		403			2,519
	Total debt securities	474,697		5,925		636			479,986
	Marketable equity securities	1,249		88		—			1,337
	Total investment securities available-for-sale	$	475,946	$	6,013	$	636		$	481,323
	Investment securities held-to-maturity	$	500	$	2	$	—		$	502
Investment securities in a continuous unrealized loss position	'
	Investment securities at December 31, 2013 and 2012 that have been in a continuous unrealized loss position for less than twelve months or twelve months or longer are as follows:
		At December 31, 2013
		Less than				Twelve Months						Total
		Twelve Months				or Longer
		Estimated		Unrealized		Estimated			Unrealized			Estimated			Unrealized
		Fair Value		Losses		Fair Value			Losses			Fair Value			Losses
		(In Thousands)
	Debt securities:
	GSE CMOs	$	221,317	$	9,861	$	16,257		$	912		$	237,574		$	10,773
	GSE MBSs	121,836		3,746		13,516			1,183			135,352			4,929
	Private-label CMOs	639		18		—			—			639			18
	SBA commercial loan asset- backed securities	32		—		192			2			224			2
	Auction-rate municipal obligations	—		—		1,775			125			1,775			125
	Corporate debt obligations	5,988		33		—			—			5,988			33
	Trust preferred securities	—		—		1,210			251			1,210			251
	Temporarily impaired debt securities	349,812		13,658		32,950			2,473			382,762			16,131
	Marketable equity securities	501		10		—			—			501			10
	Total temporarily impaired securities	$	350,313	$	13,668	$	32,950		$	2,473		$	383,263		$	16,141
		At December 31, 2012
		Less than				Twelve Months						Total
		Twelve Months				or Longer
		Estimated		Unrealized		Estimated			Unrealized			Estimated			Unrealized
		Fair Value		Losses		Fair Value			Losses			Fair Value			Losses
		(In Thousands)
	Debt securities:
	GSE CMOs	$	23,910	$	55	$	—		$	—		$	23,910		$	55
	GSE MBSs	19,186		47		235			5			19,421			52
	Private-label CMOs	25		—		—			—			25			—
	SBA commercial loan asset- backed securities	310		2		—			—			310			2
	Auction-rate municipal obligations	—		—		1,976			124			1,976			124
	Trust preferred securities and pools	—		—		1,931			403			1,931			403
	Temporarily impaired debt securities	43,431		104		4,142			532			47,573			636
	Marketable equity securities	—		—		—			—			—			—
	Total temporarily impaired securities	$	43,431	$	104	$	4,142		$	532		$	47,573		$	636
Schedule of maturities of the investments in debt securities	'
	The maturities of the investments in debt securities available-for-sale at the dates indicated are as follows:
		At December 31,
		2013						2012
		Amortized		Estimated		Weighted		Amortized			Estimated			Weighted
		Cost		Fair Value		Average		Cost			Fair Value			Average
						Rate								Rate
		(Dollars in Thousands)
	Investment securities available-for-sale:
	Within 1 year	$	13,012	$	13,062	0.82	%	$	59,396		$	59,736		1.2	%
	After 1 year through 5 years	40,204		41,187		2.9	%	25,249			25,579			1.61	%
	After 5 years through 10 years	66,447		67,075		2.23	%	50,283			52,557			3.29	%
	Over 10 years	384,967		369,794		1.9	%	339,769			342,114			1.93	%
		$	504,630	$	491,118	2	%	$	474,697		$	479,986		1.97	%
Schedule of sales of investment securities	'
		Year Ended December 31,
		2013		2012		2011
		(In Thousands)
	Sales of debt securities	$	1,210	$	166,201	$	—
	Sales of marketable equity securities	—		—		124
	Gross gains from sales	626		1,093		80
	Gross losses from sales	229		167		—

Restricted_Equity_Securities_T

Restricted Equity Securities (Tables)	12 Months Ended
	Dec. 31, 2013
Restricted Investments Note [Abstract]	'
Components of investments in the restricted equity securities of various entities	'
	Investments in the restricted equity securities of various entities are as follows:
		At December 31,
		2013		2012
		(In Thousands)
	FHLBB stock	$	50,081	$	52,188
	Federal Reserve Bank of Boston stock	16,003		15,998
	Other restricted equity securities	475		475
		$	66,559	$	68,661

Loans_and_Leases_Tables

Loans and Leases (Tables)	12 Months Ended
	Dec. 31, 2013
Loans and Leases Receivable Disclosure [Abstract]	'
Summary of loan and lease balances for the originated and acquired portfolios	'
	The following tables present loan and lease balances and weighted average coupon rates for the originated and acquired loan and lease portfolios at the dates indicated:
		At December 31, 2013
		Originated						Acquired						Total
		Balance			Weighted			Balance				Weighted		Balance		Weighted
					Average							Average				Average
					Coupon							Coupon				Coupon
		(Dollars In Thousands)
	Commercial real estate loans:
	Commercial real estate	$	1,111,750		4.34	%		$	350,235			4.42	%	$	1,461,985	4.36	%
	Multi-family mortgage	554,555			4.19	%		73,378				4.63	%	627,933		4.24	%
	Construction	102,927			3.81	%		10,778				4.37	%	113,705		3.87	%
	Total commercial real estate loans	1,769,232			4.26	%		434,391				4.46	%	2,203,623		4.3	%
	Commercial loans and leases:
	Commercial	297,684			3.68	%		110,108				4.54	%	407,792		3.91	%
	Equipment financing	485,330			7.14	%		27,694				6.6	%	513,024		7.11	%
	Condominium association	44,794			4.74	%		—				—		44,794		4.74	%
	Total commercial loans and leases	827,808			5.77	%		137,802				4.95	%	965,610		5.65	%
	Indirect automobile loans	400,531			4.98	%		—				—		400,531		4.98	%
	Consumer loans:
	Residential mortgage	411,554			3.65	%		116,631				3.93	%	528,185		3.71	%
	Home equity	132,396			3.39	%		125,065				3.88	%	257,461		3.63	%
	Other consumer	5,532			5.98	%		1,523				14.89	%	7,055		7.9	%
	Total consumer loans	549,482			3.61	%		243,219				3.98	%	792,701		3.72	%
	Total loans and leases	$	3,547,053		4.59	%		$	815,412			4.38	%	$	4,362,465	4.55	%
		At December 31, 2012
		Originated						Acquired						Total
		Balance			Weighted			Balance				Weighted		Balance		Weighted
					Average							Average				Average
					Coupon							Coupon				Coupon
		(Dollars In Thousands)
	Commercial real estate loans:
	Commercial real estate	$	871,552		4.62	%		$	429,681			4.69	%	$	1,301,233	4.64	%
	Multi-family mortgage	506,017			4.5	%		100,516				4.99	%	606,533		4.58	%
	Construction	80,913			4.2	%		17,284				4.73	%	98,197		4.29	%
	Total commercial real estate loans	1,458,482			4.56	%		547,481				4.75	%	2,005,963		4.61	%
	Commercial loans and leases:
	Commercial	230,892			3.89	%		151,385				4.72	%	382,277		4.22	%
	Equipment financing	366,297			7.69	%		54,694				6.91	%	420,991		7.59	%
	Condominium association	44,187			5.02	%		—				—		44,187		5.02	%
	Total commercial loans and leases	641,376			6.14	%		206,079				5.3	%	847,455		5.93	%
	Indirect automobile loans	542,344			5.31	%		—				—		542,344		5.31	%
	Consumer loans:
	Residential mortgage	368,095			3.87	%		143,014				4.18	%	511,109		3.93	%
	Home equity	99,683			3.45	%		161,879				4.07	%	261,562		3.83	%
	Other consumer	6,122			5.35	%		1,157				12.97	%	7,279		6.56	%
	Total consumer loans	473,900			3.78	%		306,050				4.15	%	779,950		3.92	%
	Total loans and leases	$	3,116,102		4.89	%		$	1,059,610			4.67	%	$	4,175,712	4.83	%
Schedule of activity in the accretable yield for acquired loan portfolio	'
	The following table summarizes activity in the accretable yield for the acquired loan portfolio for the periods indicated:
		Year Ended December 31,
		2013			2012				2011
		(In Thousands)
	Balance at beginning of year	$	57,812		$	(1,369	)		$	—
	Acquisitions	—			81,503				(2,504		)
	Reclassification from nonaccretable difference for loans with improved cash flows	8,477			1,550				—
	Accretion	(20,500		)	(23,872		)		1,135
	Balance at end of year	$	45,789		$	57,812			$	(1,369	)
Summary of the change in the total amounts of loans and advances, all of which were performing, to directors, executive officers and their affiliates	'
	The following table summarizes the change in the total amounts of loans and advances, to directors, executive officers and their affiliates for the periods indicated. All loans were performing at December 31, 2013.
		Year Ended December 31,
		2013			2012				2011
		(In Thousands)
	Balance at beginning of year	$	4,083		$	16,428			$	16,399
	Acquired loans	—			2,848				222
	New loans granted during the year	365			314				288
	Advances on lines of credit	1,370			109				—
	Repayments	(1,035		)	(15,281		)		(481		)
	Loan no longer classified as an insider loan	—			(335		)		—
	Loans reclassified as insider loans	11,327			—				—
	Balance at end of year	$	16,110		$	4,083			$	16,428

Allowance_for_Loan_and_Lease_L1

Allowance for Loan and Lease Losses (Tables)	12 Months Ended
	Dec. 31, 2013
Loans and Leases Receivable, Allowance [Abstract]	'
Schedule of changes in the allowance for loan and lease losses	'
	The following tables present the changes in the allowance for loan and lease losses and the recorded investment in loans and leases by portfolio segment for the periods indicated:
		Year Ended December 31, 2013
		Commercial				Commercial				Indirect				Consumer				Unallocated				Total
		Real Estate								Automobile
		(In Thousands)
	Balance at December 31, 2012	$	20,018			$	10,655			$	5,304			$	2,545			$	2,630			$	41,152
	Charge-offs	(88		)		(2,077		)		(1,714		)		(909		)		—				(4,788		)
	Recoveries	13				657				501				263				—				1,434
	Provision (credit) for loan and lease losses	3,079				5,985				(167		)		1,476				302				10,675
	Balance at December 31, 2013	$	23,022			$	15,220			$	3,924			$	3,375			$	2,932			$	48,473
		Year Ended December 31, 2012
		Commercial				Commercial				Indirect				Consumer				Unallocated				Total
		Real Estate								Automobile
		(In Thousands)
	Balance at December 31, 2011	$	15,477			$	5,997			$	5,604			$	1,577			$	3,048			$	31,703
	Charge-offs	—				(5,347		)		(2,153		)		(592		)		—				(8,092		)
	Recoveries	118				417				969				26				—				1,530
	Provision (credit) for loan and lease losses	4,423				9,588				884				1,534				(418		)		16,011
	Balance at December 31, 2012	$	20,018			$	10,655			$	5,304			$	2,545			$	2,630			$	41,152
		Year Ended December 31, 2011
		Commercial				Commercial				Indirect				Consumer				Unallocated				Total
		Real Estate								Automobile
		(In Thousands)
	Balance at December 31, 2010	$	12,398			$	5,293			$	6,952			$	1,638			$	3,414			$	29,695
	Charge-offs	(30		)		(773		)		(2,076		)		(12		)		—				(2,891		)
	Recoveries	—				330				605				8				—				943
	Provision (credit) for loan and lease losses	3,109				1,147				123				(57		)		(366		)		3,956
	Balance at December 31, 2011	$	15,477			$	5,997			$	5,604			$	1,577			$	3,048			$	31,703
Provisions for credit losses	'
	The provisions for credit losses are set forth below for the periods indicated:
		Originated												Acquired												Total
		Year Ended December 31,												Year Ended December 31,												Year Ended December 31,
		2013				2012				2011				2013				2012				2011				2013				2012			2011
		(In Thousands)
	Provision for loan and lease losses:
	Commercial real estate	$	2,563			$	4,348			$	3,109			$	516			$	75			$	—			$	3,079			$	4,423		$	3,109
	Commercial	4,917				9,513				1,147				1,068				75				—				5,985				9,588			1,147
	Indirect automobile	(167		)		884				123				—				—				—				(167		)		884			123
	Consumer	286				1,534				(57		)		1,190				—				—				1,476				1,534			(57		)
	Unallocated	302				(418		)		(366		)		—				—				—				302				(418		)	(366		)
	Total provision for loan and lease losses	7,901				15,861				3,956				2,774				150				—				10,675				16,011			3,956
	Unfunded credit commitments	254				(123		)		(325		)		—				—				—				254				(123		)	(325		)
	Total provision for credit losses	$	8,155			$	15,738			$	3,631			$	2,774			$	150			$	—			$	10,929			$	15,888		$	3,631
Summary of the recorded investments by credit quality indicator, by loan class	'
	The following tables present the recorded investment in total loans in each class (unpaid balance of loans and leases outstanding excluding deferred loan origination costs) at December 31, 2013 by credit quality indicator.
		At December 31, 2013
		Commercial				Multi-				Construction				Commercial				Equipment				Condominium				Other
		Real Estate				Family												Financing				Association				Consumer
		Mortgage				Mortgage
		(In Thousands)
	Originated:
	Loan rating:
	Pass	$	1,099,108			$	554,183			$	102,927			$	295,057			$	479,811			$	44,793			$	5,528
	OAEM	11,555				372				—				49				625				—				—
	Substandard	1,087				—				—				1,078				4,817				1				4
	Doubtful	—				—				—				1,500				77				—				—
	Total originated	1,111,750				554,555				102,927				297,684				485,330				44,794				5,532
	Acquired:
	Loan rating:
	Pass	332,145				69,310				10,090				96,779				27,535				—				1,509
	OAEM	7,556				463				688				4,617				61				—				—
	Substandard	8,645				3,605				—				8,518				98				—				14
	Doubtful	1,889				—				—				194				—				—				—
	Total acquired	350,235				73,378				10,778				110,108				27,694				—				1,523
	Total loans by class	$	1,461,985			$	627,933			$	113,705			$	407,792			$	513,024			$	44,794			$	7,055
		At December 31, 2013
		Indirect Automobile
		Dollars In Thousands				Percent
	Originated:
	Credit score:
	Over 700	$	332,140			82.9	%
	661-700	54,038				13.5	%
	660 and below	12,793				3.2	%
	Data not available	1,560				0.4	%
		$	400,531			100	%
			At December 31, 2013
			Residential Mortgage							Home Equity
			Dollars In Thousands				Percent			Dollars In Thousands				Percent
	Originated:
	Loan-to-value ratio:
	Less than 50%		$	94,500			17.9	%		$	75,372			29.3	%
	50% - 69%		149,969				28.4	%		31,504				12.2	%
	70% - 79%		139,960				26.5	%		21,161				8.2	%
	80% and over		22,772				4.3	%		3,240				1.3	%
	Data not available		4,353				0.8	%		1,119				0.4	%
	Total originated		411,554				77.9	%		132,396				51.4	%
	Acquired:
	Loan-to-value ratio:
	Less than 50%		$	23,101			4.4	%		$	84,272			32.7	%
	50%—69%		39,298				7.4	%		25,964				10.1	%
	70%—79%		31,932				6	%		13,390				5.2	%
	80% and over		19,870				3.8	%		1,208				0.5	%
	Data not available		2,430				0.5	%		231				0.1	%
	Total acquired		116,631				22.1	%		125,065				48.6	%
	Total loans		$	528,185			100	%		$	257,461			100	%
	The following tables present the recorded investment in loans in each class (unpaid balance of loans and leases outstanding excluding deferred loan origination costs) at December 31, 2012 by credit quality indicator.
		At December 31, 2012
		Commercial				Multi-				Construction				Commercial				Equipment				Condominium				Other
		Real Estate				Family												Financing				Association				Consumer
		Mortgage				Mortgage
		(In Thousands)
	Originated:
	Loan rating:
	Pass	$	863,901			$	504,883			$	80,913			$	227,201			$	359,064			$	44,179			$	6,093
	OAEM	5,686				146				—				1,196				2,979				—				—
	Substandard	1,965				988				—				502				4,213				8				29
	Doubtful	—				—				—				1,993				41				—				—
Total originated	871,552				506,017				80,913				230,892				366,297				44,187				6,122
Acquired:
Loan rating:
Pass	409,725				93,058				17,186				140,589				54,175				—				1,157
OAEM	2,740				2,439				—				1,344				286				—				—
Substandard	17,216				5,019				98				8,635				233				—				—
Doubtful	—				—				—				817				—				—				—
Total acquired	429,681				100,516				17,284				151,385				54,694				—				1,157
Total loans by class	$	1,301,233			$	606,533			$	98,197			$	382,277			$	420,991			$	44,187			$	7,279
	At December 31, 2012
	Indirect Automobile
	Dollars In Thousands				Percent
Originated:
Credit score:
Over 700	$	454,056			83.7	%
661-700	69,319				12.8	%
660 and below	16,934				3.1	%
Data not available	2,035				0.4	%
	$	542,344			100	%
		At December 31, 2012
		Residential Mortgage							Home Equity
		Dollars In Thousands				Percent			Dollars In Thousands				Percent
Originated:
Loan-to-value ratio:
Less than 50%		$	86,659			17	%		$	50,398			19.3	%
50%—69%		142,172				27.8	%		25,284				9.7	%
70%—79%		111,234				21.8	%		16,523				6.3	%
80% and over		27,858				5.4	%		6,042				2.3	%
Data not available		172				—	%		1,436				0.5	%
		368,095				72	%		99,683				38.1	%
Acquired:
Loan-to-value ratio:
Less than 50%		23,398				4.6	%		28,401				10.9	%
50%—69%		42,214				8.2	%		39,385				15.1	%
70%—79%		42,748				8.4	%		33,044				12.6	%
80% and over		31,614				6.2	%		34,267				13.1	%
Data not available		3,040				0.6	%		26,782				10.2	%
		143,014				28	%		161,879				61.9	%
Total loans		$	511,109			100	%		$	261,562			100	%
Information regarding the aging of past due loans, by loan class	'
	The following tables present an age analysis of the recorded investment in total loans and leases (unpaid balance of loans and leases outstanding excluding deferred loan origination costs) at December 31, 2013 and 2012.
		At December 31, 2013
		Past Due																								Loans and
																										Leases Past
																										Due Greater
																										Than 90 Days
		31-60				61-90				Greater				Total				Current				Total Loans				and Accruing				Nonaccrual
		Days				Days				Than												and Leases								Loans and
										90 Days																				Leases
		(In Thousands)
	Originated:
	Commercial real estate loans:
	Commercial real estate mortgage	$	4,896			$	1,393			$	169			$	6,458			$	1,105,292			$	1,111,750			$	—			$	169
	Multi-family mortgage	14,400				—				—				14,400				540,155				554,555				—				—
	Construction	—				—				—				—				102,927				102,927				—				—
	Total commercial real estate loans	19,296				1,393				169				20,858				1,748,374				1,769,232				—				169
	Commercial loans and leases:
	Commercial	2,288				75				842				3,205				294,479				297,684				—				1,551
	Equipment financing	867				1,558				2,031				4,456				480,874				485,330				—				4,086
	Condominium association	—				—				—				—				44,794				44,794				—				1
	Total commercial loans and leases	3,155				1,633				2,873				7,661				820,147				827,808				—				5,638
	Indirect automobile	5,407				857				229				6,493				394,038				400,531				10				259
	Consumer loans:
	Residential mortgage	201				—				415				616				410,938				411,554				—				1,713
	Home equity	218				—				—				218				132,178				132,396				—				462
	Other consumer	11				1				4				16				5,516				5,532				—				4
	Total consumer loans	430				1				419				850				548,632				549,482				—				2,179
	Total originated loans and leases	$	28,288			$	3,884			$	3,690			$	35,862			$	3,511,191			$	3,547,053			$	10			$	8,245
		At December 31, 2013
		Past Due																								Loans and
																										Leases Past
																										Due Greater
																										Than 90 Days
		31-60				61-90				Greater				Total				Current				Total Loans				and Accruing				Nonaccrual
		Days				Days				Than												and Leases								Loans and
										90 Days																				Leases
		(In Thousands)
	Acquired:
	Commercial real estate loans:
	Commercial real estate mortgage	$	1,221			$	87			$	4,887			$	6,195			$	344,040			$	350,235			$	3,958			$	929
	Multi-family mortgage	327				—				1,052				1,379				71,999				73,378				1,052				—
	Construction	—				409				—				409				10,369				10,778				—				—
	Total commercial real estate loans	1,548				496				5,939				7,983				426,408				434,391				5,010				929
	Commercial loans and leases:
	Commercial	2,707				121				1,931				4,759				105,349				110,108				1,235				4,597
	Equipment financing	46				41				73				160				27,534				27,694				73				29
	Total commercial loans and leases	2,753				162				2,004				4,919				132,883				137,802				1,308				4,626
	Consumer loans:
	Residential mortgage	271				777				5,329				6,377				110,254				116,631				4,468				1,162
	Home equity	1,259				552				895				2,706				122,359				125,065				117				1,525
	Other consumer	6				11				4				21				1,502				1,523				—				14
	Total consumer loans	1,536				1,340				6,228				9,104				234,115				243,219				4,585				2,701
	Total acquired loans and leases	$	5,837			$	1,998			$	14,171			$	22,006			$	793,406			$	815,412			$	10,903			$	8,256
		At December 31, 2012
		Past Due																								Loans and
																										Leases Past
																										Due Greater
																										Than 90 Days
		31-60				61-90				Greater				Total				Current				Total Loans				and Accruing				Nonaccrual
		Days				Days				Than												and Leases								Loans and
										90 Days																				Leases
		(In Thousands)
	Originated:
Commercial real estate loans:
Commercial real estate mortgage	$	1,530			$	—			$	435			$	1,965			$	869,587			$	871,552			$	434			$	1,539
Multi-family mortgage	2,410				60				988				3,458				502,559				506,017				—				1,932
Construction	2,354				816				—				3,170				77,743				80,913				—				—
Total commercial real estate loans	6,294				876				1,423				8,593				1,449,889				1,458,482				434				3,471
Commercial loans and leases:
Commercial	26				75				26				127				230,765				230,892				26				1,993
Equipment financing	2,595				1,439				1,618				5,652				360,645				366,297				—				3,817
Condominium association	—				—				—				—				44,187				44,187				—				8
Total commercial loans and leases	2,621				1,514				1,644				5,779				635,597				641,376				26				5,818
Indirect automobile	5,592				923				99				6,614				535,730				542,344				1				99
Consumer loans:
Residential mortgage	—				—				1,059				1,059				367,036				368,095				27				2,008
Home equity	—				—				33				33				99,650				99,683				—				58
Other consumer	—				2				5				7				6,115				6,122				5				29
Total consumer loans	—				2				1,097				1,099				472,801				473,900				32				2,095
Total originated loans and leases	$	14,507			$	3,315			$	4,263			$	22,085			$	3,094,017			$	3,116,102			$	493			$	11,483
	At December 31, 2012
	Past Due																								Loans and
																									Leases Past
																									Due Greater
																									Than 90 Days
	31-60				61-90				Greater				Total				Current				Total Loans				and Accruing				Nonaccrual
	Days				Days				Than												and Leases								Loans and
									90 Days																				Leases
	(In Thousands)
Acquired:
Commercial real estate loans:
Commercial real estate mortgage	$	2,911			$	—			$	7,289			$	10,200			$	419,481			$	429,681			$	6,616			$	2,475
Multi-family mortgage	2,738				395				2,178				5,311				95,205				100,516				1,857				2,301
Construction	—				—				—				—				17,284				17,284				—				—
Total commercial real estate loans	5,649				395				9,467				15,511				531,970				547,481				8,473				4,776
Commercial loans and leases:
Commercial	866				177				4,353				5,396				145,989				151,385				3,503				3,461
Equipment financing	133				21				194				348				54,346				54,694				197				56
Total commercial loans and leases	999				198				4,547				5,744				200,335				206,079				3,700				3,517
Consumer loans:
Residential mortgage	247				121				5,266				5,634				137,380				143,014				3,650				1,796
Home equity	1,582				507				607				2,696				159,183				161,879				321				658
Other consumer	7				—				—				7				1,150				1,157				—				16
Total consumer loans	1,836				628				5,873				8,337				297,713				306,050				3,971				2,470
Total acquired loans and leases	$	8,484			$	1,221			$	19,887			$	29,592			$	1,030,018			$	1,059,610			$	16,144			$	10,763
Impaired loans and leases, by loan and leases class	'
		At December 31, 2012												Year Ended December 31, 2012
		Recorded				Unpaid				Related				Average				Interest
		Investment (1)				Principal				Allowance				Recorded				Income
						Balance								Investment				Recognized
		(In Thousands)
	Originated:
	With no related allowance recorded:
	Commercial real estate	$	2,051			$	2,051			$	—			$	2,547			$	243
	Commercial	3,032				3,059				—				3,159				181
	Consumer	1,191				1,187				—				2,123				130
		6,274				6,297				—				7,829				554
	With an allowance recorded:
	Commercial real estate	2,517				2,516				241				1,142				79
	Commercial	3,422				3,559				703				3,393				305
	Consumer	3,648				3,636				596				2,918				100
		9,587				9,711				1,540				7,453				484
	Total	$	15,861			$	16,008			$	1,540			$	15,282			$	1,038
	(1) Includes nonaccrual loans of $8.8 million
		At December 31, 2012												Year Ended December 31, 2012
		Recorded				Unpaid				Related				Average				Interest
		Investment (1)				Principal				Allowance				Recorded				Income
						Balance								Investment				Recognized
		(In Thousands)
	Acquired:
	With no related allowance recorded:
	Commercial real estate	17,918				19,129				—				9,071				—
	Commercial	7,329				7,782				—				3,801				—
	Consumer	3,266				3,379				—				2,319				—
		28,513				30,290				—				15,191				—
	With an allowance recorded:
	Commercial real estate	673				684				75				366				—
	Commercial	113				121				75				109				—
	Consumer	—				—				—				—				—
		786				805				150				475				—
	Total	$	29,299			$	31,095			$	150			$	15,666			$	—
	(1) Includes nonaccrual loans of $21.5 million
		At December 31, 2011												Year Ended December 31, 2011
		Recorded				Unpaid				Related				Average				Interest
		Investment				Principal				Allowance				Recorded				Income
						Balance								Investment				Recognized
		(In Thousands)
	Originated:
	With no related allowance recorded:
	Commercial real estate	$	2,902			$	3,140			$	—			$	2,834			$	119
	Commercial	3,341				4,063				—				2,938				94
	Indirect automobile	111				111				—				100				—
	Consumer	3,126				3,126				—				3,753				159
		9,480				10,440				—				9,625				372
	With an allowance recorded:
	Commercial	604				619				190				774				58
	Consumer	339				339				35				343				7
		943				958				225				1,117				65
	Total	$	10,423			$	11,398			$	225			$	10,742			$	437
	The following tables include the recorded investment and unpaid principal balances of impaired loans and leases with the related allowance amount, if applicable, for the originated and acquired loan and lease portfolios at the dates and for the periods indicated. Also presented are the average recorded investments in the impaired loans and leases and the related amount of interest recognized during the period that the impaired loans were impaired.
		At December 31, 2013												Year Ended December 31, 2013
		Recorded				Unpaid				Related				Average				Interest
		Investment (1)				Principal				Allowance				Recorded				Income
						Balance								Investment				Recognized
		(In Thousands)
	Originated:
	With no related allowance recorded:
	Commercial real estate	$	2,009			$	2,009			$	—			$	2,184			$	92
	Commercial	4,410				4,399				—				4,257				144
Consumer	989				987				—				1,077				30
	7,408				7,395				—				7,518				266
With an allowance recorded:
Commercial real estate	1,466				1,466				184				1,464				43
Commercial	2,393				2,383				675				1,781				29
Consumer	2,448				2,440				323				3,210				97
	6,307				6,289				1,182				6,455				169
Total	$	13,715			$	13,684			$	1,182			$	13,973			$	435
(1) Includes nonaccrual loans of $5.8 million
	At December 31, 2013												Year Ended December 31, 2013
	Recorded				Unpaid				Related				Average				Interest
	Investment (1)				Principal				Allowance				Recorded				Income
					Balance								Investment				Recognized
	(In Thousands)
Acquired:
With no related allowance recorded:
Commercial real estate	$	9,176			$	10,082			$	—			$	9,639			$	251
Commercial	6,988				7,248				—				5,205				129
Consumer	1,033				1,037				—				1,333				20
	17,197				18,367				—				16,177				400
With an allowance recorded:
Commercial real estate	1,274				1,291				122				2,765				42
Commercial	1,020				1,067				169				577				5
Consumer	—				—				—				—				—
	2,294				2,358				291				3,342				47
Total	$	19,491			$	20,725			$	291			$	19,519			$	447
(1) Includes nonaccrual loans of $10.9 million
Schedule of the impaired and non-impaired loans and leases, by loan and leases class	'
	The following tables present information regarding impaired and non-impaired loans and leases at the dates indicated:
		At December 31, 2013
		Loans and Leases								Loans and Leases								Acquired Loans								Total
		Individually								Collectively Evaluated								(ASC 310-30)
		Evaluated for								for Impairment
		Impairment
		Portfolio				Allowance				Portfolio				Allowance				Portfolio				Allowance				Portfolio				Allowance
		(In Thousands)
	Commercial real estate	$	6,269			$	184			$	1,910,645			$	22,282			$	286,709			$	556			$	2,203,623			$	23,022
	Commercial	11,512				675				914,739				14,293				39,359				252				965,610				15,220
	Indirect automobile	—				—				400,531				3,924				—				—				400,531				3,924
	Consumer	4,309				323				708,640				2,618				79,752				434				792,701				3,375
	Unallocated	—				—				—				2,932				—				—				—				2,932
	Total	$	22,090			$	1,182			$	3,934,555			$	46,049			$	405,820			$	1,242			$	4,362,465			$	48,473
		At December 31, 2012
		Loans and Leases								Loans and Leases								Acquired Loans								Total
		Individually								Collectively Evaluated								(ASC 310-30)
		Evaluated for								for Impairment
		Impairment
		Portfolio				Allowance				Portfolio				Allowance				Portfolio				Allowance				Portfolio				Allowance
		(In Thousands)
	Commercial real estate	$	5,576			$	316			$	1,652,231			$	19,702			$	348,156			$	—			$	2,005,963			$	20,018
	Commercial	8,046				778				774,366				9,877				65,043				—				847,455				10,655
	Indirect automobile	—				—				542,344				5,304				—				—				542,344				5,304
	Consumer	5,237				596				672,051				1,949				102,662				—				779,950				2,545
	Unallocated	—				—				—				2,630				—				—				—				2,630
	Total	$	18,859			$	1,690			$	3,640,992			$	39,462			$	515,861			$	—			$	4,175,712			$	41,152
Summery of loans restructured or defaulted	'
	The recorded investment in troubled debt restructurings, and the associated specific allowances for loan and lease losses, in the originated and acquired loan and lease portfolios are as follows for the periods indicated:
		Year Ended December 31, 2013
					Recorded Investment								Specific												Defaulted
													Allowance for
													Loan and
		Number of			At				At End of				Lease Losses				Nonaccrual				Additional				Number of			Recorded
		Loans/			Modification				Period								Loans and				Commitment				Loans/			Investment
		Leases															Leases								Leases
		(Dollars in Thousands)
	Originated:
	Commercial real estate mortgage	1			$	1,039			$	—			$	—			$	—			$	—			—			$	—
	Commercial	2			926				918				—				—				—				—			—
	Equipment financing	5			1,557				1,415				77				861				—				2			371
	Residential mortgage	1			415				353				—				353				—				—			—
	Total	9			$	3,937			$	2,686			$	77			$	1,214			$	—			2			$	371
		Year Ended December 31, 2013
					Recorded Investment								Specific												Defaulted
													Allowance for
													Loan and
		Number of			At				At End of				Lease Losses				Nonaccrual				Additional				Number of			Recorded
		Loans/			Modification				Period								Loans and				Commitment				Loans/			Investment
		Leases															Leases								Leases
		(Dollars in Thousands)
	Acquired:
	Commercial real estate mortgage	1			$	737			$	727			$	—			$	—			$	—			—			$	—
	Commercial	6			3,209				3,135				—				1,335				—				1			1,335
	Equipment financing	—			—				—				—				—				—				—			—
	Residential mortgage	—			—				—				—				—				—				—			—
	Total	7			$	3,946			$	3,862			$	—			$	1,335			$	—			1			$	1,335
		Year Ended December 31, 2012
					Recorded Investment								Specific												Defaulted
													Allowance for
													Loan and
		Number of			At				At End of				Lease Losses				Nonaccrual				Additional				Number of			Recorded
		Loans/			Modification				Period								Loans and				Commitment				Loans/			Investment
		Leases															Leases								Leases
		(Dollars in Thousands)
	Originated:
	Commercial real estate mortgage	2			$	867			$	854			$	33			$	513			$	—			2			$	1,288
	Commercial	3			3,942				2,086				316				1,993				—				1			44
	Equipment financing	8			2,138				2,038				110				793				—				6			1,240
	Residential mortgage	6			2,422				1,724				315				294				—				3			763
	Total	19			$	9,369			$	6,702			$	774			$	3,593			$	—			12			$	3,335
		Year Ended December 31, 2012
					Recorded Investment								Specific												Defaulted
													Allowance for
													Loan and
		Number of			At				At End of				Lease Losses				Nonaccrual				Additional				Number of			Recorded
		Loans/			Modification				Period								Loans and				Commitment				Loans/			Investment
		Leases															Leases								Leases
		(Dollars in Thousands)
	Acquired:
	Commercial real estate mortgage	1			$	3,145			$	3,208			$	—			$	—			$	—			—			$	—
	Commercial	2			1,229				1,163				—				478				—				—			—
	Equipment financing	—			—				—				—				—				—				—			—
	Residential mortgage	—			—				—				—				—				—				—			—
	Total	3			$	4,374			$	4,371			$	—			$	478			$	—			—			$	—
Schedule of troubled debt restructurings by type of modification	'
	The following table sets forth the Company's end-of-period balances for troubled debt restructurings that were modified during the periods indicated, by type of modification.
		Year Ended
		December 31,
		2013				2012				2011
		(In Thousands)
	Loans modified once:
	Extended maturity	$	3,841			$	1,478			$	1,136
	Adjusted principal	908				2,185				1,456
	Adjusted interest rate	755				1,715				—
	Combination maturity, principal, interest rate	554				1,838				1,928
	Total loans modified once	$	6,058			$	7,216			$	4,520
	Loans modified more than once:
	Extended maturity	$	490			$	—			$	78
	Adjusted principal	—				3,857				1,471
	Adjusted interest rate	—				—				353
	Combination maturity, principal, interest rate	—				—				751
	Total loans modified more than once	$	490			$	3,857			$	2,653

Premises_and_Equipment_Tables

Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2013
Property, Plant and Equipment [Abstract]	'
Schedule of premises and equipment	'
	Premises and equipment consist of the following:
		At December 31,				Estimated
		2013		2012		Useful Life
		(In Thousands)				(In Years)
	Land	$	7,481	$	7,553	NA
	Office building and improvements	75,271		67,672		10 to 40
	Furniture, fixtures and equipment	25,633		22,537		3 to 10
	Software	5,018		5,063		3 to 7
	Core processing system	11,522		6,951		7.5
	Total	124,925		109,776
	Accumulated depreciation and amortization	44,420		38,985
	Total premises and equipment	$	80,505	$	70,791

Goodwill_and_Other_Intangible_1

Goodwill and Other Intangible Assets Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2013
Goodwill and Intangible Assets Disclosure [Abstract]	'
Schedule of changes in the carrying value of goodwill	'
	The changes in the carrying value of goodwill for the periods indicated were as follows:
		Year Ended December 31,
		2013		2012			2011
		(In Thousands)
	Balance at beginning of year	$	137,890	$	45,799		$	43,241
	Additions	—		93,145			2,558
	Adjustments to original goodwill	—		(1,054		)	—
	Balance at end of year	$	137,890	$	137,890		$	45,799
Schedule of composition of goodwill and other intangible assets	'
	The following is a summary of the Company's other intangible assets:
		At December 31, 2013							At December 31, 2012
		Gross		Accumulated			Carrying		Gross		Accumulated		Carrying
		Amount		Amortization			Amount		Amount		Amortization		Amount
		(In Thousands)
	Other intangible assets:
	Core deposits	$	36,172	$	20,395		$	15,777	$	36,172	$	16,399	$	19,773
	Trade name	1,600		511			1,089		1,600		267		1,333
	Trust relationship	1,568		1,547			21		1,568		1,164		404
	Other intangible	442		442			—		442		442		—
	Total other intangible assets	$	39,782	$	22,895		$	16,887	$	39,782	$	18,272	$	21,510
Schedule of estimated aggregate future amortization expense for intangible assets	'
	The estimated aggregate future amortization expense for other intangible assets for each of the next five years and thereafter is as follows:
	Year ended December 31:	Amount
		(In Thousands)
	2014	$	3,124
	2015	2,868
	2016	2,457
	2017	1,858
	2018	1,836
	Thereafter	3,655
	Total	$	15,798

Other_Assets_Tables

Other Assets (Tables)	12 Months Ended
	Dec. 31, 2013
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]	'
Schedule of information regarding the Company's investments in affordable housing projects	'
	Further information regarding the Company's investments in affordable housing projects follows:
		As of and for the
		Year Ended
		December 31,
		2013		2012		2011
		(In Thousands)
	Investments in affordable housing projects included in other assets	$	10,301	$	9,167	$	6,712
	Unfunded commitments related to affordable housing projects included in other liabilities	2,904		4,291		2,864
	Loss from investments in affordable housing projects	1,812		694		671
	Reduction in tax expense due to affordable housing tax credits	1,058		806		464

Deposits_Tables

Deposits (Tables)	12 Months Ended
	Dec. 31, 2013
Deposits [Abstract]	'
Summary of deposits	'
	A summary of deposits follows:
		31-Dec-13				31-Dec-12
		Amount		Weighted		Amount			Weighted
				Average					Average
				Rate					Rate
		(Dollars in Thousands)
	Demand checking accounts	$	707,023	—		$	623,274		—
	NOW accounts	210,602		0.07	%	212,858			0.09	%
	Savings accounts	494,734		0.25	%	515,367			0.39	%
	Money market accounts	1,487,979		0.54	%	1,253,819			0.63	%
	Total core deposit accounts	2,900,338		0.32	%	2,605,318			0.39	%
	Certificate of deposit accounts maturing:
	Within six months	381,986		0.72	%	392,138			0.91	%
	After six months but within 1 year	312,005		0.82	%	359,510			0.95	%
	After 1 year but within 2 years	141,518		1.09	%	159,747			1.09	%
	After 2 years but within 3 years	45,965		1.91	%	34,392			2.05	%
	After 3 years but within 4 years	26,046		1.65	%	37,813			2.08	%
	After 4 years but within 5 years	26,810		1.33	%	27,341			1.65	%
	5+ Years	338		1.15	%	—			—	%
	Total certificate of deposit accounts	934,668		0.91	%	1,010,941			1.06	%
	Total deposits	$	3,835,006	0.47	%	$	3,616,259		0.58	%
Schedule of interest expense on deposit balances	'
	Interest expense on deposit balances is summarized as follows:
		Year Ended December 31,
		2013		2012			2011
		(In Thousands)
	Interest-bearing deposits:
	NOW accounts	$	173	$	209		$	216
	Savings accounts	1,288		1,726			942
	Money market accounts	8,220		8,773			7,626
	Certificate of deposit accounts	9,092		10,724			10,973
	Total interest-bearing deposits	$	18,773	$	21,432		$	19,757

Borrowed_Funds_Tables

Borrowed Funds (Tables)	12 Months Ended
	Dec. 31, 2013
Debt Disclosure [Abstract]	'
Schedule of borrowed funds	'
	Borrowed funds are comprised of the following:
		At December 31,
		2013				2012
		(In Thousands)
	Advances from the FHLBB	$	768,773			$	790,865
	Repurchase agreements	34,619				51,013
	Subordinated debentures	9,163				12,091
	Total borrowed funds	$	812,555			$	853,969
Schedule of interest expense on borrowed funds	'
	Interest expense on borrowed funds for the periods indicated is as follows:
		Year Ended December 31,
		2013				2012			2011
		(In Thousands)
	Advances from the FHLBB	$	10,886			$	13,685		$	10,454
	Repurchase agreements	68				137			125
	Subordinated debentures	439				578			—
	Total interest expense on borrowed funds	$	11,393			$	14,400		$	10,579
Schedule of federal home loan bank advances	'
	FHLBB advances mature as follows:
		At December 31,
		2013										2012
		Amount				Callable			Weighted			Amount		Callable		Weighted
						Amount			Average					Amount		Average
									Rate							Rate
		(Dollars in Thousands)
	Within 1 year	$	186,035			$	—		0.71	%		$	363,485	$	17,000	1.32	%
	Over 1 year to 2 years	283,000				—			0.79	%		46,178		—		2.14	%
	Over 2 years to 3 years	92,971				32,094			2.45	%		108,000		—		1	%
	Over 3 years to 4 years	147,198				118,698			3.86	%		64,330		30,000		3.24	%
	Over 4 years to 5 years	36,625				10,071			2.51	%		149,032		112,000		3.86	%
	Over 5 years	22,944				—			3.7	%		59,840		10,000		3	%
		$	768,773			$	160,863		1.71	%		$	790,865	$	169,000	2.06	%
Schedule of information concerning repurchase agreements during the period	'
	Information concerning repurchase agreements is as follows for the periods indicated below:
		Year Ended December 31,
		2013				2012
		(Dollars In Thousands)
	Outstanding at end of year	$	34,619			$	51,013
	Average outstanding for the year	38,784				46,623
	Maximum outstanding at any month-end	48,544				51,013
	Weighted average rate at end of year	0.17		%		0.15		%
	Weighted average rate paid for the year	0.17		%		0.13		%
Summary of subordinated debentures	'
	In the acquisition of Bancorp Rhode Island, Inc., the Company assumed three subordinated debentures issued by a subsidiary of Bancorp Rhode Island, Inc. One subordinated debenture in the amount of $3.0 million was called in the first quarter of 2013 million due to its high fixed rate. The two remaining subordinated debentures are summarized below:
	At December 31, 2013:
	Issue Date		Rate		Fair			Maturity Date	Next Call Date		Carrying
					Market Rate						Amount
					at BankRI
					Acquisition
			(Dollars in Thousands)
	June 26, 2003		Variable; 3-month		6.45	%		June 26, 2033	March 26, 2014		$	4,666
			LIBOR + 3.10%
	March 17, 2004		Variable; 3-month		6.45	%		March 17, 2034	March 17, 2014		$	4,497
			LIBOR + 2.79%
	At December 31, 2012:
	Issue Date		Rate		Fair			Maturity Date	Next Call Date		Carrying
					Market Rate						Amount
					at BankRI
					Acquisition
			(Dollars in Thousands)
	22-Feb-01		Fixed; 10.2%		3	%		22-Feb-31	22-Feb-13		$	3,000
	June 26, 2003		Variable; 3-month		6.45	%		June 26, 2033	March 26, 2013		$	4,641
			LIBOR + 3.10%
	March 17, 2004		Variable; 3-month		6.45	%		March 17, 2034	March 17, 2013		$	4,450
			LIBOR + 2.79%

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2013
Commitments and Contingencies Disclosure [Abstract]	'
Schedule of financial instruments with off-balance sheet risk	'
	Financial instruments with off-balance-sheet risk at the dates indicated follow:
		At December 31,
		2013		2012
		(In Thousands)
	Financial instruments whose contract amounts represent credit risk:
	Commitments to originate loans and leases:
	Commercial real estate	$	48,973	$	158,768
	Commercial	143,252		116,235
	Residential mortgage	8,027		8,926
	Unadvanced portion of loans and leases	592,782		299,523
	Unused lines of credit:
	Home equity	205,665		165,936
	Other consumer	1,035		4,017
	Other commercial	—		965
	Unused letters of credit:
	Financial standby letters of credit	20,410		19,887
	Performance standby letters of credit	2,989		2,916
	Commercial and similar letters of credit	440		112
	Back-to-back interest rate swaps	22,418		33,221
Schedule of future minimum rental payments under noncancellable operating leases	'
	The Company leases certain office space under various noncancellable operating leases. A summary of future minimum rental payments under such leases at the dates indicated follows:
	Year ended December 31,	Minimum Rental Payments
		(In Thousands)
	2014	$	4,936
	2015	4,740
	2016	4,500
	2017	4,030
	2018	3,392
	Thereafter	12,431
	Total	$	34,029

Earnings_per_Share_Tables

Earnings per Share (Tables)	12 Months Ended
	Dec. 31, 2013
Earnings Per Share [Abstract]	'
Reconciliation of basic EPS and diluted EPS	'
	The following table is a reconciliation of basic EPS and diluted EPS:
		2013				2012				2011
		Basic		Fully		Basic		Fully		Basic		Fully
				Diluted				Diluted				Diluted
		(Dollars in Thousands, Except Per Share Amounts)
	Net income	$	35,386	$	35,386	$	37,142	$	37,142	$	27,600	$	27,600
	Weighted average shares outstanding	69,808,164		69,808,164		69,702,417		69,702,417		58,633,627		58,633,627
	Effect of dilutive securities	—		75,760		—		43,839		—		2,804
	Adjusted weighted average shares outstanding	69,808,164		69,883,924		69,702,417		69,746,256		58,633,627		58,636,431
	Earnings per share	$	0.51	$	0.51	$	0.53	$	0.53	$	0.47	$	0.47

Comprehensive_Income_Tables

Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2013
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]	'
Schedule of changes in accumulated other comprehensive (loss) income by component, net of tax	'
	Changes in accumulated other comprehensive (loss) income by component, net of tax, were as follows for the periods indicated:
		Year Ended December 31, 2013
		Investment			Postretirement			Accumulated Other
		Securities			Benefits			Comprehensive
		Available-for-Sale						Income
		(In Thousands)
	Balance at December 31, 2012	$	3,358		$	125		$	3,483
	Other comprehensive (loss) income	(11,690		)	292			(11,398		)
	Balance at December 31, 2013	$	(8,332	)	$	417		$	(7,915	)
		Year Ended December 31, 2012
		Investment			Postretirement			Accumulated Other
		Securities			Benefits			Comprehensive
		Available-for-Sale						Income
		(In Thousands)
	Balance at December 31, 2011	$	1,834		$	129		$	1,963
	Other comprehensive income (loss)	1,524			(4		)	1,520
	Balance at December 31, 2012	$	3,358		$	125		$	3,483
		Year Ended December 31, 2011
		Investment			Postretirement			Accumulated Other
		Securities			Benefits			Comprehensive
		Available-for-Sale						Income
		(In Thousands)
	Balance at December 31, 2010	$	2,185		$	163		$	2,348
	Other comprehensive loss	(351		)	(34		)	(385		)
	Balance at December 31, 2011	$	1,834		$	129		$	1,963
Summary of the amounts reclassified from accumulated other comprehensive income (loss)	'
	The following is a summary of the amounts reclassified from accumulated other comprehensive income (loss) for the years ended December 31, 2013, 2012, and 2011.
		Year Ended December 31,									Income Statement Line Affected by Reclassification
		2013			2012			2011
		(In Thousands)
	Other Comprehensive Income (Loss) Component
	Unrealized gains on investment securities available-for-sale:
		$	397		$	926		$	80		Gain on sales of securities,net
		(142		)	(328		)	(29		)	Provision for income taxes
	Total reclassifications for the period	$	255		$	598		$	51		Net income

Derivatives_and_Hedging_Activi1

Derivatives and Hedging Activities (Tables)	12 Months Ended
	Dec. 31, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Schedule of fair value and classification of derivative financial instruments on the consolidated balance sheets and the effect of the derivative financial instruments on the consolidated income statements	'
	The table below presents the fair value and classification of the Company's derivative financial instruments on the consolidated balance sheets as of December 31, 2013 and 2012, and the effect of the Company's derivative financial instruments on the consolidated income statements for the year ended December 31, 2013 and 2012:
		At December 31, 2013				Year Ended
						December 31, 2013
		Asset		Liability		Loss Recognized in
		Derivatives		Derivatives		Income on Derivatives(1)
		(In Thousands)
	Total derivatives (interest-rate products) not designated as hedging instruments	$	825	$	856	$	32
		At December 31, 2012				Year Ended
						December 31, 2012
		Asset		Liability		Loss Recognized in
		Derivatives		Derivatives		Income on Derivatives(1)
		(In Thousands)
	Total derivatives (interest-rate products) not designated as hedging instruments	$	1,317	$	1,380	$	24
	_______________________________________________________________________________
	-1	The amount of loss recognized in income represents changes related to the fair value of the interest rate products.
Schedule of offsetting derivatives and amounts subject to master netting agreements not offset in the audited consolidated balance sheet	'
	The tables below present the offsetting of derivatives and amounts subject to master netting agreements not offset in the consolidated balance sheet at the dates indicated.
		At December 31, 2013
		Gross		Gross Amounts		Net Amounts of		Gross Amounts Not Offset in the				Net Amount
		Amounts of		Offset in the		Assets Presented in		Statement of Financial Position
		Recognized		Statement of Financial Position		the Statement of Financial Position
		Assets /Liabilities						Financial Instruments		Cash Collateral (Received)/ Posted
		(In Thousands)
	Asset Derivatives	$	825	$	—	$	825	$	—	$	—	$	825
	Liability Derivatives	$	856	$	—	$	856	$	—	$	2,811	$	3,667
		At December 31, 2012
		Gross		Gross Amounts		Net Amounts of		Gross Amounts Not Offset in the				Net Amount
		Amounts of		Offset in the		Assets Presented in		Statement of Financial Position
		Recognized		Statement of Financial Position		the Statement of Financial Position
		Assets /Liabilities						Financial Instruments		Cash Collateral (Received) / Posted
		(In Thousands)
	Asset Derivatives	$	1,317	$	—	$	1,317	$	—	$	—	$	1,317
	Liability Derivatives	$	1,380	$	—	$	1,380	$	—	$	548	$	1,928

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'
Schedule of income tax expense	'
	Income tax expense is comprised of the following amounts:
		Year Ended December 31,
		2013			2012			2011
		(In Thousands)
	Current provision:
	Federal	$	12,799		$	15,558		$	14,115
	State	4,238			5,120			4,987
	Total current provision	17,037			20,678			19,102
	Deferred provision (benefit):
	Federal	2,572			389			811
	State	(128		)	274			(27		)
	Total deferred provision	2,444			663			784
	Total provision for income taxes	$	19,481		$	21,341		$	19,886
Schedule of reconciliation of income tax expense	'
	Total provision for income taxes differed from the amounts computed by applying the statutory U.S. federal income tax rate (35.0%) to income before tax expense as a result of the following:
		Year Ended December 31,
		2013			2012			2011
		(In Thousands)
	Expected income tax expense at statutory federal tax rate	$	19,830		$	20,899		$	17,047
	State taxes, net of federal income tax benefit	2,673			3,506			3,224
	Bank-owned life insurance	(383		)	(409		)	—
	Tax-exempt interest income	(310		)	(216		)	(157		)
	Non-deductible acquisition and other expenses	—			617			613
	Income attributable to noncontrolling interest in subsidiary	(768		)	(560		)	(427		)
	Tax credit—premises and equipment	(453		)	(1,593		)	—
	Tax credits from investments in affordable housing projects	(1,058		)	(806		)	(464		)
	Other, net	(50		)	(97		)	50
	Total provision for income taxes	$	19,481		$	21,341		$	19,886
	Effective income tax rate	34.4		%	35.7		%	40.8		%
Schedule of the tax effects of temporary differences that give rise to significant portions of the deferred tax assets and liabilities	'
	The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and liabilities at the dates indicated are as follows:
		At December 31,
		2013			2012
		(In Thousands)
	Deferred tax assets:
	Allowance for credit losses	$	19,754		$	16,667
	Acquisition fair value adjustments	7,430			10,013
	Unrealized loss on securities available for sale	5,119			—
	Retirement and postretirement benefits	4,159			4,822
	Deferred compensation	1,989			2,254
	Net operating loss and contribution carryovers	1,922			2,229
	Non-accrual interest	878			948
	Restricted stock and stock option plans	726			803
	Write-downs of investment securities	442			795
	Depreciation	—			235
	Accrued expenses	375			200
	Alternative minimum tax credits	31			31
	Other	33			198
	Total gross deferred tax assets	42,858			39,195
	Deferred tax liabilities:
	Identified intangible assets and goodwill	7,322			8,893
	Depreciation	2,619			—
	Unrealized gain on securities available for sale	—			2,015
	Deferred loan origination costs, net	734			736
	Investments in affordable housing projects	205			246
	Unrecognized gain relating to postretirement obligation	268			92
	Other	—			16
	Total gross deferred tax liabilities	11,148			11,998
	Net deferred tax asset	$	31,710		$	27,197

Regulatory_Capital_Requirement1

Regulatory Capital Requirements (Tables)	12 Months Ended
	Dec. 31, 2013
Regulatory Capital Requirements [Abstract]	'
Schedule of stockholders' equity reconciliation under U.S generally accepted accounting principles (GAAP) with regulatory capital	'
	The following table reconciles stockholders' equity under GAAP with regulatory capital for the Company and its subsidiaries at the dates indicated.
		The Company								Brookline Bank						BankRI					First Ipswich
		Dec. 31,								Dec. 31,						Dec. 31,					Dec. 31,
		2013				2012				2013			2012			2013			2012		2013			2012
		(In Thousands)
	Stockholders' equity	$	613,867			$	612,097			$	301,291		$	288,859		$	236,579		$	247,606	$	34,641		$	35,515
	Add: Minority interest	4,304				3,712				4,304			3,712			—			—		—			—
	Add: Subordinated debenture	9,163				12,091				—			—			—			—		—			—
	Less: Disallowed goodwill and intangible assets	154,777				159,400				7,647			7,991			106,593			110,203		5,271			5,940
	Less: Unrealized loss on available-for-sale equity securities	—				—				—			—			—			—		10			—
	Less: Net unrealized (losses) gains on available-for-sale securities	(7,915		)		3,358				(1,874		)	1,874			(4,918		)	1,303		(1,075		)	366
	Tier 1 capital	480,472				465,142				299,822			282,706			134,904			136,100		30,435			29,209
	Allowance for credit losses not to exceed 1.25% of risk-weighted assets	49,510				41,935				35,905			35,923			10,936			5,053		1,854			959
	Unrealized gains on available-for-sale equity securities	—				—				—			—			7			18		—			—
	Total risk-based capital	$	529,982			$	507,077			$	335,727		$	318,629		$	145,847		$	141,171	$	32,289		$	30,168
Schedule of the company's and the bank's actual and required capital amounts and ratios	'
	The Company's and the Banks' actual and required capital amounts and ratios are as follows:
				Actual							Minimum Required for					Minimum Required
											Capital Adequacy					To Be Considered
											Purposes					"Well-Capitalized"
				Amount				Ratio			Amount			Ratio		Amount			Ratio
				(Dollars in Thousands)
	At December 31, 2013:
	Brookline Bancorp, Inc.
	Tier 1 leverage capital ratio	(1	)	$	480,472			9.4	%		$	205,946		4	%	N/A			N/A
	Tier 1 risk-based capital ratio	(2	)	480,472				11	%		174,512			4	%	N/A			N/A
	Total risk-based capital ratio	(3	)	529,982				12.2	%		349,159			8	%	N/A			N/A
	Brookline Bank
	Tier 1 leverage capital ratio	(1	)	$	299,822			9.4	%		$	127,992		4	%	$	159,990		5	%
	Tier 1 risk-based capital ratio	(2	)	299,822				10.4	%		114,874			4	%	172,311			6	%
	Total risk-based capital ratio	(3	)	335,727				11.7	%		229,753			8	%	287,192			10	%
	BankRI
	Tier 1 leverage capital ratio	(1	)	$	134,904			8.1	%		$	66,784		4	%	$	83,480		5	%
	Tier 1 risk-based capital ratio	(2	)	134,904				10.6	%		52,904			4	%	79,355			6	%
	Total risk-based capital ratio	(3	)	145,847				11.4	%		105,782			8	%	132,228			10	%
	First Ipswich
	Tier 1 leverage capital ratio	(1	)	$	30,435			9.8	%		$	12,461		4	%	$	15,576		5	%
	Tier 1 risk-based capital ratio	(2	)	30,435				13.6	%		8,971			4	%	13,457			6	%
	Total risk-based capital ratio	(3	)	32,289				14.4	%		17,938			8	%	22,423			10	%
	At December 31, 2012:
	Brookline Bancorp, Inc.
	Tier 1 leverage capital ratio	(1	)	$	465,142			9.4	%		$	197,094		4	%	N/A			N/A
	Tier 1 risk-based capital ratio	(2	)	465,142				10.9	%		171,481			4	%	N/A			N/A
	Total risk-based capital ratio	(3	)	507,077				11.8	%		342,909			8	%	N/A			N/A
	Brookline Bank
	Tier 1 leverage capital ratio	(1	)	$	282,706			9.3	%		$	121,725		4	%	$	152,156		5	%
	Tier 1 risk-based capital ratio	(2	)	282,706				9.8	%		115,626			4	%	173,439			6	%
	Total risk-based capital ratio	(3	)	318,629				11	%		231,310			8	%	289,137			10	%
	BankRI
	Tier 1 leverage capital ratio	(1	)	$	136,100			8.5	%		$	64,047		4	%	$	80,059		5	%
	Tier 1 risk-based capital ratio	(2	)	136,100				11.5	%		47,175			4	%	70,763			6	%
	Total risk-based capital ratio	(3	)	141,171				12	%		94,350			8	%	117,937			10	%
	First Ipswich
	Tier 1 leverage capital ratio	(1	)	$	29,209			9.7	%		$	12,020		4	%	$	15,025		5	%
	Tier 1 risk-based capital ratio	(2	)	29,209				13.2	%		8,824			4	%	13,237			6	%
	Total risk-based capital ratio	(3	)	30,168				13.7	%		17,642			8	%	22,053			10	%
	_______________________________________________________________________________
	-1	Tier 1 leverage capital ratio is calculated by dividing Tier 1 capital by average assets.
	-2	Tier 1 risk-based capital ratio is calculated by dividing Tier 1 capital by risk-weighted assets.
	-3	Total risk-based capital ratio is calculated by dividing total capital by risk-weighted assets.

Employee_Benefit_Plans_Tables

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]	'
Schedule of the components of net periodic postretirement benefit cost and other amounts recognized in other comprehensive income	'
	The following table presents the components of net periodic postretirement benefit cost and other amounts recognized in other comprehensive income:
		Year Ended
		December 31,
		2013				2012				2011
		(In Thousands)
	Net periodic benefit expense:
	Service cost	$	61			$	74			$	74
	Interest cost	47				55				61
	Prior service credit	(21		)		(21		)		(21		)
	Actuarial gain	(16		)		(3		)		(4		)
	Net periodic benefit expense	$	71			$	105			$	110
	Changes in postretirement benefit obligation recognized in other comprehensive income:
	Net actuarial loss (gain)	$	489			$	11			$	(36	)
	Prior service credit	(21		)		(21		)		(21		)
	Total pre-tax changes in postretirement benefit obligation recognized in other comprehensive income	$	468			$	(10	)		$	(57	)
Schedule of effect of 1% change in assumed health care cost trend rates	'
	A 1% change in assumed health care cost trend rates would have the following effects:
		1% Increase				1% Decrease
		(In Thousands)
	Effect on total service and interest cost components of net periodic postretirement benefit costs	$	26			$	(20	)
	Effect on the accumulated postretirement benefit obligation	215				(171		)
Schedule of stock option activity	'
	Activity under the option plans was as follows:
		Options			Weighted				Aggregate				Weighted
		Outstanding			Average				Intrinsic				Average
					Exercise Price				Value				Contractual
					Per Share								Term (In Years)
		(Dollars in Thousands, Except Per Share Amounts)
	Employee Stock Options:
	Outstanding at December 31, 2010	1,128,345			$	14.08
	Granted	5,000			8.29
	Exercised	—			—
	Forfeited / Canceled	(42,500	)		14.67
	Outstanding at December 31, 2011	1,090,845			14.08
	Granted	—			—
	Exercised	—			—
	Forfeited / Canceled	(15,000	)		14.95
	Outstanding at December 31, 2012	1,075,845			14.95
	Granted	—			—
	Exercised	—			—
	Forfeited / Canceled	(841,000	)		14.95
	Outstanding at December 31, 2013	234,845			$	10.43			$	—			5.7
	Exercisable at December 31, 2013	234,845			$	10.43			$	—			5.7
Schedule of valuation assumptions used to determine fair value of each stock option award	'
	To calculate the weighted average data presented in this note and the compensation expense presented in the accompanying financial statements, the fair value of each stock option award was estimated on the date of grant using the Black-Scholes option pricing model with the following valuation assumptions:
		Year Ended December 31,
		2011
	Dividend yield	4.3	%
	Expected volatility	34.38	%
	Risk-free interest rate	1.85	%
	Expected life of options	7

Fair_Value_of_Financial_Instru1

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2013
Fair value of assets	'
Summary of the carrying values and estimated fair values	'
	Assets and liabilities measured at fair value on a recurring basis at December 31, 2013 and 2012 are as follows:
		Carrying Value as of December 31, 2013
		Level 1			Level 2			Level 3				Total
		(In Thousands)
	Assets:
	Securities available-for-sale:
	GSEs	$	—		$	12,180		$	—			$	12,180
	Municipal obligations	—			1,086			—				1,086
	Auction-rate municipal obligations	—			—			1,775				1,775
	Corporate debt obligations	—			28,224			—				28,224
	Trust preferred securities and pools	—			1,210			—				1,210
	GSE CMOs	—			243,644			—				243,644
	GSE MBSs	—			199,401			—				199,401
	Private-label CMOs	—			3,355			—				3,355
	SBA commercial loan asset-backed securities	—			243			—				243
	Marketable equity securities	1,310			—			—				1,310
	Total securities available-for-sale	$	1,310		$	489,343		$	1,775			$	492,428
	Interest-rate swaps	$	—		$	825		$	—			$	825
	Liabilities:
	Interest-rate swaps	$	—		$	856		$	—			$	856
		Carrying Value as of December 31, 2012
		Level 1			Level 2			Level 3				Total
		(In Thousands)
	Assets:
	Investment securities available-for-sale:
	GSEs	$	—		$	69,809		$	—			$	69,809
	Municipal obligations	—			1,101			—				1,101
	Auction-rate municipal obligations	—			—			1,976				1,976
	Corporate debt obligations	—			10,685			—				10,685
	Trust preferred securities and pools	—			1,578			941				2,519
	GSE CMOs	—			217,001			—				217,001
	GSE MBSs	—			169,648			—				169,648
	Private-label CMOs	—			6,866			—				6,866
	SBA commercial loan asset-backed securities	—			381			—				381
	Marketable equity securities	1,337			—			—				1,337
	Total investment securities available-for-sale	$	1,337		$	477,069		$	2,917			$	481,323
	Interest-rate swaps	$	—		$	1,317		$	—			$	1,317
	Liabilities:
	Interest-rate swaps	$	—		$	1,380		$	—			$	1,380
Schedule of assets and liabilities measured at fair value on a non-recurring basis	'
	Assets and liabilities measured at fair value on a non-recurring basis at December 31, 2013 and 2012 are summarized below:
		Carrying Value as of December 31, 2013
		Level 1			Level 2			Level 3				Total
		(In Thousands)
	Assets measured at fair value on a non-recurring basis:
	Collateral-dependent impaired loans and leases	$	—		$	—		$	12,099			$	12,099
	Other real estate owned	—			—			577				577
	Repossessed assets	—			1,001			—				1,001
		$	—		$	1,001		$	12,676			$	13,677
		Carrying Value as of December 31, 2012
		Level 1			Level 2			Level 3				Total
		(In Thousands)
	Assets measured at fair value on a non-recurring basis:
	Collateral-dependent impaired loans and leases	$	—		$	36,749		$	—			$	36,749
	Other real estate owned	—			903			—				903
	Repossessed assets	—			588			—				588
		$	—		$	38,240		$	—			$	38,240
Schedule of quantitative information about significant unobservable inputs (Level 3) for assets measured at fair value on a recurring basis	'
	The table below presents quantitative information about significant unobservable inputs (Level 3) for assets measured at fair value on a recurring basis at December 31, 2013.
		Fair Value			Valuation Technique		Unobservable Input	Range		Weighted
										Average
										Yields
		(Dollars in Thousands)
	Auction-rate municipal obligations	$	1,775		Discounted cash flow		Discount rate	0-5%		4	%
	Collateral-dependent impaired loans and leases	$	12,099		Appraisal of collateral (1)
	Other real estate owned	$	577		Appraisal of collateral (1)
	(1) For impaired loans deemed collateral dependent, where impairment is measured using the fair value of the collateral, the Bank will either obtain a new appraisal or use another available source of collateral assessment to determine a reasonable estimate of the fair value of the collateral.
Schedule of reconciliation of all assets measured at fair value on a recurring basis using significant unobservable inputs (Level 3)	'
	The reconciliation of all assets measured at fair value on a recurring basis using significant unobservable inputs (Level 3) is as follows for the periods indicated:
		Year Ended December 31,
		2013			2012
		(In Thousands)
	Investment securities available-for-sale, beginning of year	$	2,917		$	3,208
	Acquired, BankRI	—			184
	Principal paydowns and other	(1,150		)	(836		)
	Total unrealized gains included in other comprehensive income	8			361
	Investment securities available-for-sale, end of year	$	1,775		$	2,917
Excludes Financial Instruments For Which The Carrying Amount Approximates Fair Value	'
Fair value of assets	'
Schedule of assets and liabilities measured at fair value on a non-recurring basis	'
	Financial liabilities for which the fair value approximates carrying value include non-maturity deposits, short-term borrowings and accrued interest payable.
								Fair Value Measurements
		Carrying			Estimated			Level 1				Level 2		Level 3
		Value			Fair Value			Inputs				Inputs		Inputs
		(In Thousands)
	31-Dec-13
	Financial assets:
	Investment securities held-to-maturity	$	500		$	500		$	—			$	—	$	500
	Loans held for sale	13,372			13,372			—				13,372		—
	Loans and leases, net	4,313,992			4,552,556			—				—		4,552,556
	Financial liabilities:
	Certificates of deposit	934,668			938,703			—				938,703		—
	Borrowed funds	812,555			815,910			—				815,910		—
	31-Dec-12
	Financial assets:
	Investment securities held-to-maturity	$	500		$	502		$	—			$	—	$	502
	Loans held for sale	3,233			3,233			—				3,233		—
	Loans and leases, net	4,134,560			4,193,678			—				—		4,193,678
	Financial liabilities:
	Certificates of deposit	1,010,941			1,019,916			—				1,019,916		—
	Borrowed funds	853,969			872,046			—				872,046		—

Condensed_Parent_Company_Finan1

Condensed Parent Company Financial Statements (Tables)	12 Months Ended
	Dec. 31, 2013
Condensed Financial Information of Parent Company Only Disclosure [Abstract]	'
Condensed balance sheet	'
	Balance Sheets
		At December 31,
		2013			2012
		(In Thousands)
	ASSETS
	Cash and due from banks	$	12,438		$	4,547
	Short-term investments	33			33
	Total cash and cash equivalents	12,471			4,580
	Restricted equity securities	100			100
	Loan to Brookline Bank ESOP	2,252			2,502
	Premises and equipment, net	11,850			8,202
	Deferred tax asset	—			1,879
	Investment in subsidiaries, at equity	575,375			592,961
	Goodwill	35,267			35,267
	Other assets	6,185			1,893
	Total assets	$	643,500		$	647,384
	LIABILITIES AND STOCKHOLDERS' EQUITY
	Demand checking accounts	$	—		$	41
	Borrowed funds	9,163			12,091
	Deferred tax liability	1,195			—
	Accrued expenses and other liabilities	19,275			23,155
	Total liabilities	29,633			35,287
	Stockholders' equity:
	Common stock	757			757
	Additional paid-in capital	617,538			618,426
	Retained earnings, partially restricted	64,903			53,358
	Accumulated other comprehensive (loss) income	(7,915		)	3,483
	Treasury stock, at cost; 5,171,985 shares and 5,373,733 shares, respectively	(59,826		)	(62,107		)
	Unallocated common stock held by ESOP; 291,666 shares and 333,918 shares, respectively	(1,590		)	(1,820		)
	Total Brookline Bancorp, Inc. stockholders' equity	613,867			612,097
	Total liabilities and stockholders' equity	$	643,500		$	647,384
Condensed statement of income	'
	Statements of Income
		Year Ended December 31,
		2013			2012			2011
		(In Thousands)
	Interest and dividend income:
	Dividend income from subsidiaries	$	30,000		$	30,000		$	167,003
	Short-term investments	—			—			1
	Loan to Brookline Bank ESOP	205			227			249
	Total interest and dividend income	30,205			30,227			167,253
	Interest expense:
	Borrowed funds and subordinated debt	442			589			91
	Net interest income	29,763			29,638			167,162
	Non-interest expense:
	Compensation and employee benefits	2,305			11,302			—
	Occupancy	16			—			—
	Equipment and data processing	4,263			1,395			—
	Directors' fees	590			580			225
	Franchise taxes	223			175			180
	Professional services	583			2,773			1,758
	Advertising and marketing	6			11			—
	Other	2,386			2,477			229
	Total non-interest expense	10,372			18,713			2,392
	Income before income taxes	19,391			10,925			164,770
	(Credit) provision for income taxes	(4,035		)	(7,050		)	285
	Income before distributions in excess of net income of subsidiaries	23,426			17,975			164,485
	Distributions less than (in excess of) net income of subsidiaries	11,960			19,167			(136,885		)
	Net income	$	35,386		$	37,142		$	27,600
Condensed statement of cash flows	'
	Statements of Cash Flows
		Year Ended December 31,
		2013			2012			2011
		(In Thousands)
	Cash flows from operating activities:
	Net income attributable to parent company	$	35,386		$	37,142		$	27,600
	Adjustments to reconcile net income to net cash provided from operating activities:
	Distributions in excess (less than) of net income of subsidiaries	(11,960		)	(19,167		)	137,227
	Other operating activities, net	16,555			(5,617		)	1,202
	Net cash provided from operating activities	39,981			12,358			166,029
	Cash flows from investing activities:
	Acquisitions, net of cash and cash equivalents acquired	—			(89,258		)	(19,729		)
	Monies in escrow—Bancorp Rhode Island, Inc. acquisition	—			112,983			(112,983		)
	Repayment of ESOP loan by Brookline Bank	250			250			250
	Purchase of restricted equity securities	—			(100		)	—
	Purchase of premises and equipment	(5,458		)	(8,557		)	—
	Net cash provided from (used in) investing activities	(5,208		)	15,318			(132,462		)
	Cash flows from financing activities:
	(Decrease) increase in demand deposit, NOW, savings and money market accounts	(41		)	41			—
	Payment of dividends on common stock	(23,841		)	(23,777		)	(19,964		)
	Repayment of subordinated and other debt	(3,000		)	—			(13,985		)
	Income tax benefit from vesting of recognition and retention plan shares, exercise of non-incentive stock options, payment of dividend equivalent rights and dividend distribution on allocated ESOP shares	—			—			79
	Net cash used in financing activities	(26,882		)	(23,736		)	(33,870		)
	Net increase (decrease) in cash and cash equivalents	7,891			3,940			(303		)
	Cash and cash equivalents at beginning of year	4,580			640			943
	Cash and cash equivalents at end of year	$	12,471		$	4,580		$	640
	Supplemental disclosures of cash flow information:
	Cash paid during the year for:
	Interest on subordinated debt	$	480		$	795		$	—
	Income taxes	19,137			16,981			—
	Acquisition of Bancorp Rhode Island:
	Fair value of assets acquired, net of cash and cash equivalents acquired	$	—		$	1,571,817		$	—
	Fair value of liabilities assumed	—			1,481,535			—
	Acquisition of First Ipswich Bancorp:
	Fair value of assets acquired, net of cash and cash equivalents acquired	$	—		$	—		$	246,186
	Fair value of liabilities assumed	—			—			251,978

Quarterly_Results_of_Operation1

Quarterly Results of Operations (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]	'
Schedule of quarterly results of operations	'
		2013 Quarters
		Fourth			Third			Second			First
		(Dollars in Thousands Except Per Share Data)
	Interest and dividend income	$	51,049		$	50,823		$	52,900		$	51,612
	Interest expense	7,275			7,411			7,537			7,943
	Net interest income	43,774			43,412			45,363			43,669
	Provision for credit losses	3,887			2,748			2,439			1,855
	Net interest income after provision for credit losses	39,887			40,664			42,924			41,814
	Loss on investment in affordable housing projects	(318		)	(558		)	(624		)	(312		)
	Gain on sales of securities, net	397			—			—			—
	Other non-interest income	3,828			4,011			3,762			3,639
	Amortization of identified intangible assets	(1,127		)	(1,154		)	(1,177		)	(1,165		)
	Other non-interest expense	(30,193		)	(28,399		)	(29,638		)	(29,607		)
	Income before income taxes	12,474			14,564			15,247			14,369
	Provision for income taxes	4,325			4,645			5,382			5,129
	Net income	8,149			9,919			9,865			9,240
	Less net income attributable to noncontrolling interest in subsidiary	495			490			375			427
	Net income attributable to Brookline Bancorp, Inc.	$	7,654		$	9,429		$	9,490		$	8,813
	Earnings per share:
	Basic	$	0.11		$	0.14		$	0.14		$	0.13
	Diluted	0.11			0.13			0.14			0.13
	Average common shares outstanding:
	Basic	69,862,175			69,830,953			69,774,703			69,762,784
	Diluted	69,951,683			69,913,765			69,833,541			69,830,630
	Common stock price:
	High	$	9.58		$	10.08		$	9.14		$	9.39
	Low	8.72			8.81			8.23			8.66
	Dividends per share	$	0.085		$	0.085		$	0.085		$	0.085
		2012 Quarters
		Fourth			Third			Second			First
		(Dollars in Thousands Except Per Share Data)
	Interest income	$	52,976		$	55,394		$	51,839		$	52,991
	Interest expense	8,412			8,983			9,080			9,357
	Net interest income	44,564			46,411			42,759			43,634
	Provision for credit losses	3,101			2,862			6,678			3,247
	Net interest income after provision for credit losses	41,463			43,549			36,081			40,387
	Gain on sales of securities, net	129			—			797			—
	Gain on sales of loans and leases	1,898			—			—			—
	Loss from investments in affordable housing projects	(239		)	(73		)	(244		)	(138		)
	Other non-interest income	4,716			3,858			4,168			3,733
	Amortization of identified intangible assets	(1,797		)	(1,271		)	(1,271		)	(1,283		)
	Other non-interest expense	(27,072		)	(29,165		)	(27,350		)	(31,166		)
	Income before income taxes	19,098			16,898			12,181			11,533
	Provision for income taxes	6,868			5,176			4,398			4,899
	Net income	12,230			11,722			7,783			6,634
	Less net income attributable to noncontrolling interest in subsidiary	367			321			254			285
	Net income attributable to Brookline Bancorp, Inc.	$	11,863		$	11,401		$	7,529		$	6,349
	Earnings per share:
	Basic	$	0.17		$	0.16		$	0.11		$	0.09
	Diluted	0.17			0.16			0.11			0.09
	Average common shares outstanding:
	Basic	69,742,225			69,716,283			69,677,656			69,664,619
	Diluted	69,799,324			69,754,473			69,715,890			69,665,873
	Common stock price:
	High	$	8.9		$	9.25		$	9.49		$	9.78
	Low	7.54			8.13			8.46			8.37
	Dividends per share	$	0.085		$	0.085		$	0.085		$	0.085

Basis_of_Presentation_Details

Basis of Presentation (Details) (USD $)	12 Months Ended
	Dec. 31, 2013
	bank
	office
Basis of Presentation	'
Number of full-service banking offices	23
FDIC insurance limit per person	$250,000
Number of banks on whose deposits insurance coverage was offered	3
Percentage of insurance offered	100.00%
Cash and cash equivalents, maximum original maturity period (in months)	'3 months
Number of days past due, non-accrual status (in days)	'90 days
Period after which a non-accrual loan is restructured (in months)	'6 months
BOLI, as percentage of capital plus reserves, maximum (as a percent)	10.00%
Minimum percentage of likelihood of tax benefit being recognized for being recognized in the financial statements	50.00%
Eastern Funding LLC	'
Basis of Presentation	'
Percentage of ownership in subsidiary	84.80%
BankRI	'
Basis of Presentation	'
Number of full-service banking offices	18
First Ipswich Bancorp:	'
Basis of Presentation	'
Number of full-service banking offices	6

Acquisitions_Details

Acquisitions (Details) (USD $)	0 Months Ended			0 Months Ended
Share data in Millions, unless otherwise specified	Jan. 02, 2012	Jan. 03, 2012	Dec. 31, 2013	Feb. 28, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
	Bancorp Rhode Island, Inc.:	Bancorp Rhode Island, Inc.:	Bancorp Rhode Island, Inc.:	First Ipswich Bancorp:	First Ipswich Bancorp:	First Ipswich Bancorp:	First Ipswich Bancorp:
			branch	branch
Acquisitions	'	'	'	'	'	'	'
Number of branches acquired	'	'	18	6	'	'	'
Total consideration paid	$205,800,000	'	'	'	'	'	'
Shares of common stock issued as partial consideration for acquisition	11	11	'	'	'	'	'
Par value	100,000	'	'	'	'	'	'
Shares of common stock issued as partial consideration for acquisition	92,800,000	'	'	'	'	'	'
Cash consideration paid in acquisition	113,000,000	'	'	19,700,000	'	'	'
Shares of common stock issued for each share of acquiree as consideration for acquisition	4.686	'	'	'	'	'	'
Fair value of assets acquired in acquisition	'	'	'	271,600,000	'	'	'
Fair value of liabilities assumed	'	'	'	252,000,000	'	'	'
Expense related to transaction	'	'	'	'	$0	$0	$200,000

Cash_and_ShortTerm_Investments2

Cash and Short-Term Investments (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Cash, Cash Equivalents, and Short-term Investments [Abstract]	'	'
Average amount required to be held with Federal Reserve Bank	$5,300,000	$3,700,000
Aggregate reserves	54,200,000	41,700,000
Short-term investments	'	'
Money market funds	10,000	20,000
Federal funds sold	55,347,000	38,636,000
Short-term investment, total	$55,357,000	$38,656,000
Maximum maturity period consider to classify as mutual funds assets (in days)	'90 days	'

Investment_Securities_Details

Investment Securities (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Securities available for Sale:	'	'
Amortized Cost	$505,889,000	$475,946,000
Gross Unrealized Gains	2,680,000	6,013,000
Gross Unrealized Losses	16,141,000	636,000
Estimated Fair Value	492,428,000	481,323,000
Investment securities held-to-maturity	'	'
Amortized Cost	500,000	500,000
Gross Unrealized Gains	0	2,000
Estimated Fair Value	500,000	502,000
Investment securities available-for-sale	492,428,000	481,323,000
Net Unrealized Gain (Loss)	13,500,000	5,400,000
Fair value of available-for-sale security for first portfolio	383,300,000	'
Percentage of first portfolio for available-for-sale securities	77.80%	'
Net unrealized loss for first available-for-sale security portfolio	16,100,000	'
Fair value of available-for-sale security for second portfolio	'	47,600,000
Percentage of second portfolio for available-for-sale securities	'	9.90%
Net unrealized loss for second available-for-sale security portfolio	'	600,000
Available for sale securities pledged as collateral	402,500,000	309,700,000
Debt securities:	'	'
Securities available for Sale:	'	'
Amortized Cost	504,630,000	474,697,000
Gross Unrealized Gains	2,619,000	5,925,000
Gross Unrealized Losses	16,131,000	636,000
Estimated Fair Value	491,118,000	479,986,000
Investment securities held-to-maturity	'	'
Investment securities available-for-sale	491,118,000	479,986,000
GSEs	'	'
Securities available for Sale:	'	'
Amortized Cost	12,138,000	69,504,000
Gross Unrealized Gains	42,000	305,000
Gross Unrealized Losses	0	0
Estimated Fair Value	12,180,000	69,809,000
Investment securities held-to-maturity	'	'
Investment securities available-for-sale	12,180,000	69,809,000
GSE CMOs	'	'
Securities available for Sale:	'	'
Amortized Cost	254,331,000	215,670,000
Gross Unrealized Gains	86,000	1,386,000
Gross Unrealized Losses	10,773,000	55,000
Estimated Fair Value	243,644,000	217,001,000
Investment securities held-to-maturity	'	'
Investment securities available-for-sale	243,644,000	217,001,000
GSE MBSs	'	'
Securities available for Sale:	'	'
Amortized Cost	202,478,000	165,996,000
Gross Unrealized Gains	1,852,000	3,704,000
Gross Unrealized Losses	4,929,000	52,000
Estimated Fair Value	199,401,000	169,648,000
Investment securities held-to-maturity	'	'
Investment securities available-for-sale	199,401,000	169,648,000
Private-label collateralized mortgage obligations	'	'
Securities available for Sale:	'	'
Amortized Cost	3,258,000	6,719,000
Gross Unrealized Gains	115,000	147,000
Gross Unrealized Losses	18,000	0
Estimated Fair Value	3,355,000	6,866,000
Investment securities held-to-maturity	'	'
Investment securities available-for-sale	3,355,000	6,866,000
SBA commercial loan asset-backed securities	'	'
Securities available for Sale:	'	'
Amortized Cost	245,000	383,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	2,000	2,000
Estimated Fair Value	243,000	381,000
Investment securities held-to-maturity	'	'
Investment securities available-for-sale	243,000	381,000
Auction-rate municipal obligations	'	'
Securities available for Sale:	'	'
Amortized Cost	1,900,000	2,100,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	125,000	124,000
Estimated Fair Value	1,775,000	1,976,000
Investment securities held-to-maturity	'	'
Investment securities available-for-sale	1,775,000	1,976,000
Municipal obligations	'	'
Securities available for Sale:	'	'
Amortized Cost	1,068,000	1,058,000
Gross Unrealized Gains	18,000	43,000
Gross Unrealized Losses	0	0
Estimated Fair Value	1,086,000	1,101,000
Investment securities held-to-maturity	'	'
Investment securities available-for-sale	1,086,000	1,101,000
Corporate debt obligations	'	'
Securities available for Sale:	'	'
Amortized Cost	27,751,000	10,481,000
Gross Unrealized Gains	506,000	204,000
Gross Unrealized Losses	33,000	0
Estimated Fair Value	28,224,000	10,685,000
Investment securities held-to-maturity	'	'
Investment securities available-for-sale	28,224,000	10,685,000
Pooled Trust Preferred Securities	'	'
Securities available for Sale:	'	'
Amortized Cost	1,461,000	2,786,000
Gross Unrealized Gains	0	136,000
Gross Unrealized Losses	251,000	403,000
Estimated Fair Value	1,210,000	2,519,000
Investment securities held-to-maturity	'	'
Investment securities available-for-sale	1,210,000	2,519,000
Marketable equity securities	'	'
Securities available for Sale:	'	'
Amortized Cost	1,259,000	1,249,000
Gross Unrealized Gains	61,000	88,000
Gross Unrealized Losses	10,000	0
Estimated Fair Value	1,310,000	1,337,000
Investment securities held-to-maturity	'	'
Investment securities available-for-sale	$1,310,000	$1,337,000

Investment_Securities_Details_

Investment Securities (Details 2) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Less than 12 months	'	'
Fair Value	$350,313	$43,431
Unrealized Losses	13,668	104
12 months or Longer	'	'
Fair Value	32,950	4,142
Unrealized Losses	2,473	532
Total	'	'
Fair Value	383,263	47,573
Unrealized Losses	16,141	636
Debt Securities	'	'
Less than 12 months	'	'
Fair Value	349,812	43,431
Unrealized Losses	13,658	104
12 months or Longer	'	'
Fair Value	32,950	4,142
Unrealized Losses	2,473	532
Total	'	'
Fair Value	382,762	47,573
Unrealized Losses	16,131	636
GSE CMOs	'	'
Less than 12 months	'	'
Fair Value	221,317	23,910
Unrealized Losses	9,861	55
12 months or Longer	'	'
Fair Value	16,257	0
Unrealized Losses	912	0
Total	'	'
Fair Value	237,574	23,910
Unrealized Losses	10,773	55
GSE MBS	'	'
Less than 12 months	'	'
Fair Value	121,836	19,186
Unrealized Losses	3,746	47
12 months or Longer	'	'
Fair Value	13,516	235
Unrealized Losses	1,183	5
Total	'	'
Fair Value	135,352	19,421
Unrealized Losses	4,929	52
Private-label collateralized mortgage obligations	'	'
Less than 12 months	'	'
Fair Value	639	25
Unrealized Losses	18	0
12 months or Longer	'	'
Fair Value	0	0
Unrealized Losses	0	0
Total	'	'
Fair Value	639	25
Unrealized Losses	18	0
SBA commercial loan asset-backed securities	'	'
Less than 12 months	'	'
Fair Value	32	310
Unrealized Losses	0	2
12 months or Longer	'	'
Fair Value	192	0
Unrealized Losses	2	0
Total	'	'
Fair Value	224	310
Unrealized Losses	2	2
Auction-rate municipal obligations	'	'
Less than 12 months	'	'
Fair Value	0	0
Unrealized Losses	0	0
12 months or Longer	'	'
Fair Value	1,775	1,976
Unrealized Losses	125	124
Total	'	'
Fair Value	1,775	1,976
Unrealized Losses	125	124
Corporate debt obligations	'	'
Less than 12 months	'	'
Fair Value	5,988	'
Unrealized Losses	33	'
12 months or Longer	'	'
Fair Value	0	'
Unrealized Losses	0	'
Total	'	'
Fair Value	5,988	'
Unrealized Losses	33	'
Trust preferred securities	'	'
Less than 12 months	'	'
Fair Value	0	0
Unrealized Losses	0	0
12 months or Longer	'	'
Fair Value	1,210	1,931
Unrealized Losses	251	403
Total	'	'
Fair Value	1,210	1,931
Unrealized Losses	251	403
Marketable equity securities	'	'
Less than 12 months	'	'
Fair Value	501	0
Unrealized Losses	10	0
12 months or Longer	'	'
Fair Value	0	0
Unrealized Losses	0	0
Total	'	'
Fair Value	501	0
Unrealized Losses	$10	$0

Investment_Securities_Details_1

Investment Securities (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Investment Securities	'	'	'
Estimated Fair Value	$492,428,000	$481,323,000	'
Net Unrealized Gain (Loss)	13,500,000	5,400,000	'
Purchases of securities available-for-sale	171,231,000	326,104,000	45,361,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	383,263,000	47,573,000	'
Amortized Cost	505,889,000	475,946,000	'
Gross gains from sales	626,000	1,093,000	80,000
Gross losses from sales	229,000	167,000	0
US Government Sponsored Enterprises Debt Securities Excluding Specified Securities [Member]	'	'	'
Investment Securities	'	'	'
Estimated Fair Value	18,900,000	10,000,000	'
GSEs	'	'	'
Investment Securities	'	'	'
Estimated Fair Value	12,180,000	69,809,000	'
Net Unrealized Gain (Loss)	42,000	300,000	'
Number of securities in unrealized loss positions	0	0	'
Number of securities	5	28	'
SBA commercial loan asset-backed securities	'	'	'
Investment Securities	'	'	'
Estimated Fair Value	243,000	381,000	'
Net Unrealized Gain (Loss)	-2,000	-2,000	'
Number of securities in unrealized loss positions	7	8	'
Number of securities	9	11	'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	224,000	310,000	'
GSE MBS	'	'	'
Investment Securities	'	'	'
Estimated Fair Value	443,045,000	386,649,000	'
Net Unrealized Gain (Loss)	13,764,000	4,983,000	'
Number of securities in unrealized loss positions	86	32	'
Number of securities	232	224	'
Purchases of securities available-for-sale	149,500,000	326,100,000	'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	135,352,000	19,421,000	'
Private-label collateralized mortgage obligations	'	'	'
Investment Securities	'	'	'
Estimated Fair Value	3,400,000	6,900,000	'
Net Unrealized Gain (Loss)	100,000	100,000	'
Number of securities in unrealized loss positions	2	1	'
Number of securities	11	11	'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	639,000	25,000	'
Auction-rate municipal obligations	'	'	'
Investment Securities	'	'	'
Estimated Fair Value	1,775,000	1,976,000	'
Net Unrealized Gain (Loss)	-100,000	-100,000	'
Number of securities in unrealized loss positions	3	'	'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,775,000	1,976,000	'
Municipal obligations	'	'	'
Investment Securities	'	'	'
Estimated Fair Value	1,086,000	1,101,000	'
Number of securities in unrealized loss positions	0	0	'
Number of securities	2	2	'
Corporate debt obligations	'	'	'
Investment Securities	'	'	'
Estimated Fair Value	28,200,000	10,700,000	'
Net Unrealized Gain (Loss)	500,000	200,000	'
Number of securities in unrealized loss positions	2	0	'
Number of securities	11	8	'
Purchases of securities available-for-sale	21,700,000	'	'
Number of securities for which obligations are non-investment grade	1	1	'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	5,988,000	'	'
Trust preferred securities	'	'	'
Investment Securities	'	'	'
Estimated Fair Value	1,200,000	2,500,000	'
Net Unrealized Gain (Loss)	-300,000	-300,000	'
Number of securities in unrealized loss positions	'	3	'
Number of securities	'	5	'
Number of trust preferred securities	2	3	'
Number of trust preferred pools number	'	2	'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,210,000	1,931,000	'
Securities under unrealized loss position as a percentage of amortized cost of total securities	17.20%	14.50%	'
Number of securities sold	2	'	'
Net gain on sale of securities	400,000	'	'
Marketable equity securities	'	'	'
Investment Securities	'	'	'
Estimated Fair Value	1,300,000	'	'
Net Unrealized Gain (Loss)	100,000	'	'
Number of securities in unrealized loss positions	1	0	'
Number of securities	4	4	'
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	501,000	0	'
Securities under unrealized loss position as a percentage of amortized cost of total securities	0.80%	'	'
State of Israel Bonds [Member]	'	'	'
Investment Securities	'	'	'
Payments to acquire investments	'	'	500,000
Carrying value of investment	'	'	500,000
Fair value of investment	'	'	$500,000
LIBOR [Member] | State of Israel Bonds [Member]	'	'	'
Investment Securities	'	'	'
Spread on variable rate	'	'	0.13%

Investment_Securities_Details_2

Investment Securities (Details 4) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Available for Sale, Amortized Cost	'	'
Within 1 year	$13,012,000	$59,396,000
After 1 year through 5 years	40,204,000	25,249,000
After 5 years through 10 years	66,447,000	50,283,000
Over 10 years	384,967,000	339,769,000
Total	504,630,000	474,697,000
Available for Sale, Estimated Fair Value	'	'
Within 1 year	13,062,000	59,736,000
After 1 year through 5 years	41,187,000	25,579,000
After 5 years through 10 years	67,075,000	52,557,000
Over 10 years	369,794,000	342,114,000
Total	491,118,000	479,986,000
Available for Sale, Weighted Average Rate	'	'
Within 1 year (as a percent)	0.82%	1.20%
After 1 year through 5 years (as a percent)	2.90%	1.61%
After 5 years through 10 years (as a percent)	2.23%	3.29%
Over 10 years (as a percent)	1.90%	1.93%
Total (as a percent)	2.00%	1.97%
Estimated fair value of debt securities have right to call or prepay the obligations	3,700,000	8,900,000
Estimated fair value of debt securities have right to call or prepay the obligations, scheduled maturities of less than one year	700,000	'
Estimated fair value of debt securities have right to call or prepay the obligations, scheduled maturities of after one year through five years	'	4,800,000
Estimated fair value of debt securities have right to call or prepay the obligations, scheduled maturities after five years through ten years	'	200,000
Estimated fair value of debt securities have right to call or prepay the obligations, scheduled maturities of which is after 10 years	$3,000,000	$3,900,000

Investment_Securities_Details_3

Investment Securities (Details 5) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Securities available for Sale:	'	'	'
Proceeds from sales	$1,210	$166,201	$124
Gross gains from sales	626	1,093	80
Gross losses from sales	229	167	0
Debt Securities	'	'	'
Securities available for Sale:	'	'	'
Proceeds from sales	1,210	166,201	0
Marketable equity securities	'	'	'
Securities available for Sale:	'	'	'
Proceeds from sales	$0	$0	$124

Restricted_Equity_Securities_D

Restricted Equity Securities (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Restricted equity securities	'	'
Restricted equity securities	$66,559,000	$68,661,000
FHLBB stock	'	'
Restricted equity securities	'	'
Restricted equity securities	50,081,000	52,188,000
Dividend rate (as a percent)	0.38%	'
Amount of capital stock proposed to be repurchased by FHLBB	300,000,000	'
Federal Reserve Bank of Boston stock	'	'
Restricted equity securities	'	'
Restricted equity securities	16,003,000	15,998,000
Other restricted equity securities	'	'
Restricted equity securities	'	'
Restricted equity securities	$475,000	$475,000

Loans_and_Leases_Details

Loans and Leases (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Originated loans	$3,547,053,000	$3,116,102,000	'
Originated, Weighted Average Coupon (as a percent)	4.59%	4.89%	'
Acquired loans	815,412,000	1,059,610,000	'
Acquired, Weighted Average Coupon (as a percent)	4.38%	4.67%	'
Total loans and leases	4,362,465,000	4,175,712,000	'
Acquired, Weighted Average Coupon (as a percent)	4.55%	4.83%	'
Percentage of loans to aggregate outstanding amount in Other areas of the United States	61.80%	'	'
Proceeds from loans and leases sold	56,389,000	104,029,000	41,687,000
Commercial real estate loans	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Originated loans	1,769,232,000	1,458,482,000	'
Originated, Weighted Average Coupon (as a percent)	4.26%	4.56%	'
Acquired loans	434,391,000	547,481,000	'
Acquired, Weighted Average Coupon (as a percent)	4.46%	4.75%	'
Total loans and leases	2,203,623,000	2,005,963,000	'
Acquired, Weighted Average Coupon (as a percent)	4.30%	4.61%	'
Commercial real estate	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Originated loans	1,111,750,000	871,552,000	'
Originated, Weighted Average Coupon (as a percent)	4.34%	4.62%	'
Acquired loans	350,235,000	429,681,000	'
Acquired, Weighted Average Coupon (as a percent)	4.42%	4.69%	'
Total loans and leases	1,461,985,000	1,301,233,000	'
Acquired, Weighted Average Coupon (as a percent)	4.36%	4.64%	'
Multi-family mortgage	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Originated loans	554,555,000	506,017,000	'
Originated, Weighted Average Coupon (as a percent)	4.19%	4.50%	'
Acquired loans	73,378,000	100,516,000	'
Acquired, Weighted Average Coupon (as a percent)	4.63%	4.99%	'
Total loans and leases	627,933,000	606,533,000	'
Acquired, Weighted Average Coupon (as a percent)	4.24%	4.58%	'
Construction	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Originated loans	102,927,000	80,913,000	'
Originated, Weighted Average Coupon (as a percent)	3.81%	4.20%	'
Acquired loans	10,778,000	17,284,000	'
Acquired, Weighted Average Coupon (as a percent)	4.37%	4.73%	'
Total loans and leases	113,705,000	98,197,000	'
Acquired, Weighted Average Coupon (as a percent)	3.87%	4.29%	'
Commercial loans	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Originated loans	827,808,000	641,376,000	'
Originated, Weighted Average Coupon (as a percent)	5.77%	6.14%	'
Acquired loans	137,802,000	206,079,000	'
Acquired, Weighted Average Coupon (as a percent)	4.95%	5.30%	'
Total loans and leases	965,610,000	847,455,000	'
Acquired, Weighted Average Coupon (as a percent)	5.65%	5.93%	'
Commercial	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Originated loans	297,684,000	230,892,000	'
Originated, Weighted Average Coupon (as a percent)	3.68%	3.89%	'
Acquired loans	110,108,000	151,385,000	'
Acquired, Weighted Average Coupon (as a percent)	4.54%	4.72%	'
Total loans and leases	407,792,000	382,277,000	'
Acquired, Weighted Average Coupon (as a percent)	3.91%	4.22%	'
Equipment financing	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Originated loans	485,330,000	366,297,000	'
Originated, Weighted Average Coupon (as a percent)	7.14%	7.69%	'
Acquired loans	27,694,000	54,694,000	'
Acquired, Weighted Average Coupon (as a percent)	6.60%	6.91%	'
Total loans and leases	513,024,000	420,991,000	'
Acquired, Weighted Average Coupon (as a percent)	7.11%	7.59%	'
Percentage of loans to aggregate outstanding amount in the greater New York/New Jersey Metropolitan area and northeastern states	38.20%	'	'
Proceeds from loans and leases sold	'	19,600,000	'
Gain on sale of loans and leases sold	'	1,900,000	'
Condominium association	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Originated loans	44,794,000	44,187,000	'
Originated, Weighted Average Coupon (as a percent)	4.74%	5.02%	'
Acquired loans	0	0	'
Acquired, Weighted Average Coupon (as a percent)	0.00%	0.00%	'
Total loans and leases	44,794,000	44,187,000	'
Acquired, Weighted Average Coupon (as a percent)	4.74%	5.02%	'
Indirect automobile	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Originated loans	400,531,000	542,344,000	'
Originated, Weighted Average Coupon (as a percent)	4.98%	5.31%	'
Acquired loans	0	0	'
Acquired, Weighted Average Coupon (as a percent)	0.00%	0.00%	'
Total loans and leases	400,531,000	542,344,000	'
Acquired, Weighted Average Coupon (as a percent)	4.98%	5.31%	'
Consumer loans	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Originated loans	549,482,000	473,900,000	'
Originated, Weighted Average Coupon (as a percent)	3.61%	3.78%	'
Acquired loans	243,219,000	306,050,000	'
Acquired, Weighted Average Coupon (as a percent)	3.98%	4.15%	'
Total loans and leases	792,701,000	779,950,000	'
Acquired, Weighted Average Coupon (as a percent)	3.72%	3.92%	'
Residential mortgage	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Originated loans	411,554,000	368,095,000	'
Originated, Weighted Average Coupon (as a percent)	3.65%	3.87%	'
Acquired loans	116,631,000	143,014,000	'
Acquired, Weighted Average Coupon (as a percent)	3.93%	4.18%	'
Total loans and leases	528,185,000	511,109,000	'
Acquired, Weighted Average Coupon (as a percent)	3.71%	3.93%	'
Home equity	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Originated loans	132,396,000	99,683,000	'
Originated, Weighted Average Coupon (as a percent)	3.39%	3.45%	'
Acquired loans	125,065,000	161,879,000	'
Acquired, Weighted Average Coupon (as a percent)	3.88%	4.07%	'
Total loans and leases	257,461,000	261,562,000	'
Acquired, Weighted Average Coupon (as a percent)	3.63%	3.83%	'
Other consumer	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Originated loans	5,532,000	6,122,000	'
Originated, Weighted Average Coupon (as a percent)	5.98%	5.35%	'
Acquired loans	1,523,000	1,157,000	'
Acquired, Weighted Average Coupon (as a percent)	14.89%	12.97%	'
Total loans and leases	$7,055,000	$7,279,000	'
Acquired, Weighted Average Coupon (as a percent)	7.90%	6.56%	'

Loans_and_Leases_Details_2

Loans and Leases (Details 2) (Acquired, USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Acquired	'	'	'
Summarized activity in accretable yield for the acquired loan portfolio	'	'	'
Balance at the beginning of the period	$57,812,000	($1,369,000)	$0
Acquisitions	0	81,503,000	-2,504,000
Reclassification from nonaccretable difference for loans with improved cash flows	8,477,000	1,550,000	0
Accretion	-20,500,000	-23,872,000	1,135,000
Balance at the end of the period	45,789,000	57,812,000	-1,369,000
Provision for loans losses	900,000	0	'
Aggregate remaining nonaccretable difference (representing both principal and interest) applicable to acquired loans	$4,500,000	$13,000,000	'

Loans_and_Leases_Details_3

Loans and Leases (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Change in the total amounts of loans and advances, all of which were performing	'	'	'
Balance at the end of the year	'	'	$16,428,000
Directors, executive officers and their affiliates	'	'	'
Change in the total amounts of loans and advances, all of which were performing	'	'	'
Balance at the beginning of the year	4,083,000	16,428,000	16,399,000
Acquired loans	0	2,848,000	222,000
New loans granted during the year	365,000	314,000	288,000
Advances on lines of credit	1,370,000	109,000	0
Repayments	-1,035,000	-15,281,000	-481,000
Loan no longer classified as an insider loan	0	-335,000	0
Loans reclassified as insider loans	11,327,000	0	0
Balance at the end of the year	16,110,000	4,083,000	16,428,000
Unfunded commitments on extensions of credit	$11,700,000	$6,900,000	'

Loans_and_Leases_Details_4

Loans and Leases (Details 4) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Billions, unless otherwise specified
Loans and Leases Receivable Disclosure [Abstract]	'	'
Loans and leases pledged as collateral	$1.20	$1.50

Allowance_for_Loan_and_Lease_L2

Allowance for Loan and Lease Losses (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Changes in allowance for loan losses	'	'	'	'	'	'	'	'	'	'	'
Balance at the beginning of the period	'	'	'	$41,152,000	'	'	'	$31,703,000	$41,152,000	$31,703,000	$29,695,000
Charge-offs	'	'	'	'	'	'	'	'	-4,788,000	-8,092,000	-2,891,000
Recoveries	'	'	'	'	'	'	'	'	1,434,000	1,530,000	943,000
Provision (credit) for loan and lease losses	'	'	'	'	'	'	'	'	10,675,000	16,011,000	3,956,000
Balance at the end of the period	48,473,000	'	'	'	41,152,000	'	'	'	48,473,000	41,152,000	31,703,000
Provisions for credit losses	'	'	'	'	'	'	'	'	'	'	'
Total provision for loan losses	'	'	'	'	'	'	'	'	10,675,000	16,011,000	3,956,000
Unfunded credit commitments liability	'	'	'	'	'	'	'	'	254,000	-123,000	-325,000
Total provision for credit losses	3,887,000	2,748,000	2,439,000	1,855,000	3,101,000	2,862,000	6,678,000	3,247,000	10,929,000	15,888,000	3,631,000
Unfunded credit commitments liability included in other liabilities	1,000,000	'	'	'	700,000	'	'	'	1,000,000	700,000	800,000
General allowance for loan and lease losses	44,100,000	'	'	'	36,800,000	'	'	'	44,100,000	36,800,000	'
Increase in general portion of the allowance for loan and lease losses	'	'	'	'	'	'	'	'	7,300,000	'	'
Specific allowance for loan and lease losses	1,500,000	'	'	'	1,700,000	'	'	'	1,500,000	1,700,000	'
Increase (decrease) in specific portion of the allowance for loan and lease losses	'	'	'	'	'	'	'	'	-200,000	'	'
Unallocated allowance for loan and lease losses	2,900,000	'	'	'	2,600,000	'	'	'	2,900,000	2,600,000	'
Increase in unallocated portion of the allowance for loan and lease losses	'	'	'	'	'	'	'	'	300,000	'	'
Originated	'	'	'	'	'	'	'	'	'	'	'
Changes in allowance for loan losses	'	'	'	'	'	'	'	'	'	'	'
Provision (credit) for loan and lease losses	'	'	'	'	'	'	'	'	7,901,000	15,861,000	3,956,000
Provisions for credit losses	'	'	'	'	'	'	'	'	'	'	'
Total provision for loan losses	'	'	'	'	'	'	'	'	7,901,000	15,861,000	3,956,000
Unfunded credit commitments liability	'	'	'	'	'	'	'	'	254,000	-123,000	-325,000
Total provision for credit losses	'	'	'	'	'	'	'	'	8,155,000	15,738,000	3,631,000
Acquired	'	'	'	'	'	'	'	'	'	'	'
Changes in allowance for loan losses	'	'	'	'	'	'	'	'	'	'	'
Provision (credit) for loan and lease losses	'	'	'	'	'	'	'	'	2,774,000	150,000	0
Provisions for credit losses	'	'	'	'	'	'	'	'	'	'	'
Total provision for loan losses	'	'	'	'	'	'	'	'	2,774,000	150,000	0
Unfunded credit commitments liability	'	'	'	'	'	'	'	'	0	0	0
Total provision for credit losses	'	'	'	'	'	'	'	'	2,774,000	150,000	0
Commercial Real Estate	'	'	'	'	'	'	'	'	'	'	'
Changes in allowance for loan losses	'	'	'	'	'	'	'	'	'	'	'
Balance at the beginning of the period	'	'	'	20,018,000	'	'	'	15,477,000	20,018,000	15,477,000	12,398,000
Charge-offs	'	'	'	'	'	'	'	'	-88,000	0	-30,000
Recoveries	'	'	'	'	'	'	'	'	13,000	118,000	0
Provision (credit) for loan and lease losses	'	'	'	'	'	'	'	'	3,079,000	4,423,000	3,109,000
Balance at the end of the period	23,022,000	'	'	'	20,018,000	'	'	'	23,022,000	20,018,000	15,477,000
Provisions for credit losses	'	'	'	'	'	'	'	'	'	'	'
Total provision for loan losses	'	'	'	'	'	'	'	'	3,079,000	4,423,000	3,109,000
Number of loan classes within specific portfolio	3	'	'	'	'	'	'	'	3	'	'
Commercial Real Estate | Originated	'	'	'	'	'	'	'	'	'	'	'
Changes in allowance for loan losses	'	'	'	'	'	'	'	'	'	'	'
Provision (credit) for loan and lease losses	'	'	'	'	'	'	'	'	2,563,000	4,348,000	3,109,000
Provisions for credit losses	'	'	'	'	'	'	'	'	'	'	'
Total provision for loan losses	'	'	'	'	'	'	'	'	2,563,000	4,348,000	3,109,000
Commercial Real Estate | Acquired	'	'	'	'	'	'	'	'	'	'	'
Changes in allowance for loan losses	'	'	'	'	'	'	'	'	'	'	'
Provision (credit) for loan and lease losses	'	'	'	'	'	'	'	'	516,000	75,000	0
Provisions for credit losses	'	'	'	'	'	'	'	'	'	'	'
Total provision for loan losses	'	'	'	'	'	'	'	'	516,000	75,000	0
Commercial	'	'	'	'	'	'	'	'	'	'	'
Changes in allowance for loan losses	'	'	'	'	'	'	'	'	'	'	'
Balance at the beginning of the period	'	'	'	10,655,000	'	'	'	5,997,000	10,655,000	5,997,000	5,293,000
Charge-offs	'	'	'	'	'	'	'	'	-2,077,000	-5,347,000	-773,000
Recoveries	'	'	'	'	'	'	'	'	657,000	417,000	330,000
Provision (credit) for loan and lease losses	'	'	'	'	'	'	'	'	5,985,000	9,588,000	1,147,000
Balance at the end of the period	15,220,000	'	'	'	10,655,000	'	'	'	15,220,000	10,655,000	5,997,000
Provisions for credit losses	'	'	'	'	'	'	'	'	'	'	'
Total provision for loan losses	'	'	'	'	'	'	'	'	5,985,000	9,588,000	1,147,000
Number of loan classes within specific portfolio	3	'	'	'	'	'	'	'	3	'	'
Commercial | Originated	'	'	'	'	'	'	'	'	'	'	'
Changes in allowance for loan losses	'	'	'	'	'	'	'	'	'	'	'
Provision (credit) for loan and lease losses	'	'	'	'	'	'	'	'	4,917,000	9,513,000	1,147,000
Provisions for credit losses	'	'	'	'	'	'	'	'	'	'	'
Total provision for loan losses	'	'	'	'	'	'	'	'	4,917,000	9,513,000	1,147,000
Commercial | Acquired	'	'	'	'	'	'	'	'	'	'	'
Changes in allowance for loan losses	'	'	'	'	'	'	'	'	'	'	'
Provision (credit) for loan and lease losses	'	'	'	'	'	'	'	'	1,068,000	75,000	0
Provisions for credit losses	'	'	'	'	'	'	'	'	'	'	'
Total provision for loan losses	'	'	'	'	'	'	'	'	1,068,000	75,000	0
Indirect automobile	'	'	'	'	'	'	'	'	'	'	'
Changes in allowance for loan losses	'	'	'	'	'	'	'	'	'	'	'
Balance at the beginning of the period	'	'	'	5,304,000	'	'	'	5,604,000	5,304,000	5,604,000	6,952,000
Charge-offs	'	'	'	'	'	'	'	'	-1,714,000	-2,153,000	-2,076,000
Recoveries	'	'	'	'	'	'	'	'	501,000	969,000	605,000
Provision (credit) for loan and lease losses	'	'	'	'	'	'	'	'	-167,000	884,000	123,000
Balance at the end of the period	3,924,000	'	'	'	5,304,000	'	'	'	3,924,000	5,304,000	5,604,000
Provisions for credit losses	'	'	'	'	'	'	'	'	'	'	'
Total provision for loan losses	'	'	'	'	'	'	'	'	-167,000	884,000	123,000
Indirect automobile | Originated	'	'	'	'	'	'	'	'	'	'	'
Changes in allowance for loan losses	'	'	'	'	'	'	'	'	'	'	'
Provision (credit) for loan and lease losses	'	'	'	'	'	'	'	'	-167,000	884,000	123,000
Provisions for credit losses	'	'	'	'	'	'	'	'	'	'	'
Total provision for loan losses	'	'	'	'	'	'	'	'	-167,000	884,000	123,000
Indirect automobile | Acquired	'	'	'	'	'	'	'	'	'	'	'
Changes in allowance for loan losses	'	'	'	'	'	'	'	'	'	'	'
Provision (credit) for loan and lease losses	'	'	'	'	'	'	'	'	0	0	0
Provisions for credit losses	'	'	'	'	'	'	'	'	'	'	'
Total provision for loan losses	'	'	'	'	'	'	'	'	0	0	0
Consumer	'	'	'	'	'	'	'	'	'	'	'
Changes in allowance for loan losses	'	'	'	'	'	'	'	'	'	'	'
Balance at the beginning of the period	'	'	'	2,545,000	'	'	'	1,577,000	2,545,000	1,577,000	1,638,000
Charge-offs	'	'	'	'	'	'	'	'	-909,000	-592,000	-12,000
Recoveries	'	'	'	'	'	'	'	'	263,000	26,000	8,000
Provision (credit) for loan and lease losses	'	'	'	'	'	'	'	'	1,476,000	1,534,000	-57,000
Balance at the end of the period	3,375,000	'	'	'	2,545,000	'	'	'	3,375,000	2,545,000	1,577,000
Provisions for credit losses	'	'	'	'	'	'	'	'	'	'	'
Total provision for loan losses	'	'	'	'	'	'	'	'	1,476,000	1,534,000	-57,000
Number of loan classes within specific portfolio	3	'	'	'	'	'	'	'	3	'	'
Consumer | Originated	'	'	'	'	'	'	'	'	'	'	'
Changes in allowance for loan losses	'	'	'	'	'	'	'	'	'	'	'
Provision (credit) for loan and lease losses	'	'	'	'	'	'	'	'	286,000	1,534,000	-57,000
Provisions for credit losses	'	'	'	'	'	'	'	'	'	'	'
Total provision for loan losses	'	'	'	'	'	'	'	'	286,000	1,534,000	-57,000
Consumer | Acquired	'	'	'	'	'	'	'	'	'	'	'
Changes in allowance for loan losses	'	'	'	'	'	'	'	'	'	'	'
Provision (credit) for loan and lease losses	'	'	'	'	'	'	'	'	1,190,000	0	0
Provisions for credit losses	'	'	'	'	'	'	'	'	'	'	'
Total provision for loan losses	'	'	'	'	'	'	'	'	1,190,000	0	0
Unallocated	'	'	'	'	'	'	'	'	'	'	'
Changes in allowance for loan losses	'	'	'	'	'	'	'	'	'	'	'
Balance at the beginning of the period	'	'	'	2,630,000	'	'	'	3,048,000	2,630,000	3,048,000	3,414,000
Charge-offs	'	'	'	'	'	'	'	'	0	0	0
Recoveries	'	'	'	'	'	'	'	'	0	0	0
Provision (credit) for loan and lease losses	'	'	'	'	'	'	'	'	302,000	-418,000	-366,000
Balance at the end of the period	2,932,000	'	'	'	2,630,000	'	'	'	2,932,000	2,630,000	3,048,000
Provisions for credit losses	'	'	'	'	'	'	'	'	'	'	'
Total provision for loan losses	'	'	'	'	'	'	'	'	302,000	-418,000	-366,000
Unallocated | Originated	'	'	'	'	'	'	'	'	'	'	'
Changes in allowance for loan losses	'	'	'	'	'	'	'	'	'	'	'
Provision (credit) for loan and lease losses	'	'	'	'	'	'	'	'	302,000	-418,000	-366,000
Provisions for credit losses	'	'	'	'	'	'	'	'	'	'	'
Total provision for loan losses	'	'	'	'	'	'	'	'	302,000	-418,000	-366,000
Unallocated | Acquired	'	'	'	'	'	'	'	'	'	'	'
Changes in allowance for loan losses	'	'	'	'	'	'	'	'	'	'	'
Provision (credit) for loan and lease losses	'	'	'	'	'	'	'	'	0	0	0
Provisions for credit losses	'	'	'	'	'	'	'	'	'	'	'
Total provision for loan losses	'	'	'	'	'	'	'	'	$0	$0	$0

Allowance_for_Loan_and_Lease_L3

Allowance for Loan and Lease Losses (Details 2) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Credit Quality Information	'	'
Recorded investment	$4,362,465	$4,175,712
Originated	'	'
Credit Quality Information	'	'
Recorded investment	3,547,053	3,116,102
Acquired	'	'
Credit Quality Information	'	'
Recorded investment	815,412	1,059,610
Commercial real estate mortgage	'	'
Credit Quality Information	'	'
Recorded investment	1,461,985	1,301,233
Commercial real estate mortgage | Originated	'	'
Credit Quality Information	'	'
Recorded investment	1,111,750	871,552
Commercial real estate mortgage | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	350,235	429,681
Commercial real estate mortgage | Pass | Originated	'	'
Credit Quality Information	'	'
Recorded investment	1,099,108	863,901
Commercial real estate mortgage | Pass | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	332,145	409,725
Commercial real estate mortgage | OAEM | Originated	'	'
Credit Quality Information	'	'
Recorded investment	11,555	5,686
Commercial real estate mortgage | OAEM | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	7,556	2,740
Commercial real estate mortgage | Substandard | Originated	'	'
Credit Quality Information	'	'
Recorded investment	1,087	1,965
Commercial real estate mortgage | Substandard | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	8,645	17,216
Commercial real estate mortgage | Doubtful | Originated	'	'
Credit Quality Information	'	'
Recorded investment	0	0
Commercial real estate mortgage | Doubtful | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	1,889	0
Multi-family mortgage	'	'
Credit Quality Information	'	'
Recorded investment	627,933	606,533
Multi-family mortgage | Originated	'	'
Credit Quality Information	'	'
Recorded investment	554,555	506,017
Multi-family mortgage | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	73,378	100,516
Multi-family mortgage | Pass | Originated	'	'
Credit Quality Information	'	'
Recorded investment	554,183	504,883
Multi-family mortgage | Pass | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	69,310	93,058
Multi-family mortgage | OAEM | Originated	'	'
Credit Quality Information	'	'
Recorded investment	372	146
Multi-family mortgage | OAEM | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	463	2,439
Multi-family mortgage | Substandard | Originated	'	'
Credit Quality Information	'	'
Recorded investment	0	988
Multi-family mortgage | Substandard | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	3,605	5,019
Multi-family mortgage | Doubtful | Originated	'	'
Credit Quality Information	'	'
Recorded investment	0	0
Multi-family mortgage | Doubtful | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	0	0
Construction	'	'
Credit Quality Information	'	'
Recorded investment	113,705	98,197
Construction | Originated	'	'
Credit Quality Information	'	'
Recorded investment	102,927	80,913
Construction | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	10,778	17,284
Construction | Pass | Originated	'	'
Credit Quality Information	'	'
Recorded investment	102,927	80,913
Construction | Pass | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	10,090	17,186
Construction | OAEM | Originated	'	'
Credit Quality Information	'	'
Recorded investment	0	0
Construction | OAEM | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	688	0
Construction | Substandard | Originated	'	'
Credit Quality Information	'	'
Recorded investment	0	0
Construction | Substandard | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	0	98
Construction | Doubtful | Originated	'	'
Credit Quality Information	'	'
Recorded investment	0	0
Construction | Doubtful | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	0	0
Commercial	'	'
Credit Quality Information	'	'
Recorded investment	407,792	382,277
Commercial | Originated	'	'
Credit Quality Information	'	'
Recorded investment	297,684	230,892
Commercial | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	110,108	151,385
Commercial | Pass | Originated	'	'
Credit Quality Information	'	'
Recorded investment	295,057	227,201
Commercial | Pass | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	96,779	140,589
Commercial | OAEM | Originated	'	'
Credit Quality Information	'	'
Recorded investment	49	1,196
Commercial | OAEM | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	4,617	1,344
Commercial | Substandard | Originated	'	'
Credit Quality Information	'	'
Recorded investment	1,078	502
Commercial | Substandard | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	8,518	8,635
Commercial | Doubtful | Originated	'	'
Credit Quality Information	'	'
Recorded investment	1,500	1,993
Commercial | Doubtful | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	194	817
Equipment financing	'	'
Credit Quality Information	'	'
Recorded investment	513,024	420,991
Equipment financing | Originated	'	'
Credit Quality Information	'	'
Recorded investment	485,330	366,297
Equipment financing | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	27,694	54,694
Equipment financing | Pass | Originated	'	'
Credit Quality Information	'	'
Recorded investment	479,811	359,064
Equipment financing | Pass | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	27,535	54,175
Equipment financing | OAEM | Originated	'	'
Credit Quality Information	'	'
Recorded investment	625	2,979
Equipment financing | OAEM | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	61	286
Equipment financing | Substandard | Originated	'	'
Credit Quality Information	'	'
Recorded investment	4,817	4,213
Equipment financing | Substandard | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	98	233
Equipment financing | Doubtful | Originated	'	'
Credit Quality Information	'	'
Recorded investment	77	41
Equipment financing | Doubtful | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	0	0
Condominium association	'	'
Credit Quality Information	'	'
Recorded investment	44,794	44,187
Condominium association | Originated	'	'
Credit Quality Information	'	'
Recorded investment	44,794	44,187
Condominium association | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	0	0
Condominium association | Pass | Originated	'	'
Credit Quality Information	'	'
Recorded investment	44,793	44,179
Condominium association | Pass | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	0	0
Condominium association | OAEM | Originated	'	'
Credit Quality Information	'	'
Recorded investment	0	0
Condominium association | OAEM | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	0	0
Condominium association | Substandard | Originated	'	'
Credit Quality Information	'	'
Recorded investment	1	8
Condominium association | Substandard | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	0	0
Condominium association | Doubtful | Originated	'	'
Credit Quality Information	'	'
Recorded investment	0	0
Condominium association | Doubtful | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	0	0
Indirect automobile	'	'
Credit Quality Information	'	'
Recorded investment	400,531	542,344
Indirect automobile | Originated	'	'
Credit Quality Information	'	'
Recorded investment	400,531	542,344
Percentage of loans to aggregate outstanding amount	100.00%	100.00%
Indirect automobile | Credit score, Over 700 | Originated	'	'
Credit Quality Information	'	'
Recorded investment	332,140	454,056
Percentage of loans to aggregate outstanding amount	82.90%	83.70%
Indirect automobile | Credit score, 661-700 | Originated	'	'
Credit Quality Information	'	'
Recorded investment	54,038	69,319
Percentage of loans to aggregate outstanding amount	13.50%	12.80%
Indirect automobile | Credit score, 660 and below | Originated	'	'
Credit Quality Information	'	'
Recorded investment	12,793	16,934
Percentage of loans to aggregate outstanding amount	3.20%	3.10%
Indirect automobile | Data not available | Originated	'	'
Credit Quality Information	'	'
Recorded investment	1,560	2,035
Percentage of loans to aggregate outstanding amount	0.40%	0.40%
Residential mortgage	'	'
Credit Quality Information	'	'
Recorded investment	528,185	511,109
Percentage of loans to aggregate outstanding amount	100.00%	100.00%
Residential mortgage | Originated	'	'
Credit Quality Information	'	'
Recorded investment	411,554	368,095
Percentage of loans to aggregate outstanding amount	77.90%	72.00%
Residential mortgage | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	116,631	143,014
Percentage of loans to aggregate outstanding amount	22.10%	28.00%
Residential mortgage | Loan-to-value ratio, less than 50% | Originated	'	'
Credit Quality Information	'	'
Recorded investment	94,500	86,659
Percentage of loans to aggregate outstanding amount	17.90%	17.00%
Residential mortgage | Loan-to-value ratio, less than 50% | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	23,101	23,398
Percentage of loans to aggregate outstanding amount	4.40%	4.60%
Residential mortgage | Loan-to-value ratio, 50% - 69% | Originated	'	'
Credit Quality Information	'	'
Recorded investment	149,969	142,172
Percentage of loans to aggregate outstanding amount	28.40%	27.80%
Residential mortgage | Loan-to-value ratio, 50% - 69% | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	39,298	42,214
Percentage of loans to aggregate outstanding amount	7.40%	8.20%
Residential mortgage | Loan-to-value ratio, 70% - 79% | Originated	'	'
Credit Quality Information	'	'
Recorded investment	139,960	111,234
Percentage of loans to aggregate outstanding amount	26.50%	21.80%
Residential mortgage | Loan-to-value ratio, 70% - 79% | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	31,932	42,748
Percentage of loans to aggregate outstanding amount	6.00%	8.40%
Residential mortgage | Loan-to-value ratio, 80% and greater than | Originated	'	'
Credit Quality Information	'	'
Recorded investment	22,772	27,858
Percentage of loans to aggregate outstanding amount	4.30%	5.40%
Residential mortgage | Loan-to-value ratio, 80% and greater than | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	19,870	31,614
Percentage of loans to aggregate outstanding amount	3.80%	6.20%
Residential mortgage | Data not available | Originated	'	'
Credit Quality Information	'	'
Recorded investment	4,353	172
Percentage of loans to aggregate outstanding amount	0.80%	0.00%
Residential mortgage | Data not available | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	2,430	3,040
Percentage of loans to aggregate outstanding amount	0.50%	0.60%
Home equity	'	'
Credit Quality Information	'	'
Recorded investment	257,461	261,562
Percentage of loans to aggregate outstanding amount	100.00%	100.00%
Home equity | Originated	'	'
Credit Quality Information	'	'
Recorded investment	132,396	99,683
Percentage of loans to aggregate outstanding amount	51.40%	38.10%
Home equity | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	125,065	161,879
Percentage of loans to aggregate outstanding amount	48.60%	61.90%
Home equity | Loan-to-value ratio, less than 50% | Originated	'	'
Credit Quality Information	'	'
Recorded investment	75,372	50,398
Percentage of loans to aggregate outstanding amount	29.30%	19.30%
Home equity | Loan-to-value ratio, less than 50% | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	84,272	28,401
Percentage of loans to aggregate outstanding amount	32.70%	10.90%
Home equity | Loan-to-value ratio, 50% - 69% | Originated	'	'
Credit Quality Information	'	'
Recorded investment	31,504	25,284
Percentage of loans to aggregate outstanding amount	12.20%	9.70%
Home equity | Loan-to-value ratio, 50% - 69% | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	25,964	39,385
Percentage of loans to aggregate outstanding amount	10.10%	15.10%
Home equity | Loan-to-value ratio, 70% - 79% | Originated	'	'
Credit Quality Information	'	'
Recorded investment	21,161	16,523
Percentage of loans to aggregate outstanding amount	8.20%	6.30%
Home equity | Loan-to-value ratio, 70% - 79% | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	13,390	33,044
Percentage of loans to aggregate outstanding amount	5.20%	12.60%
Home equity | Loan-to-value ratio, 80% and greater than | Originated	'	'
Credit Quality Information	'	'
Recorded investment	3,240	6,042
Percentage of loans to aggregate outstanding amount	1.30%	2.30%
Home equity | Loan-to-value ratio, 80% and greater than | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	1,208	34,267
Percentage of loans to aggregate outstanding amount	0.50%	13.10%
Home equity | Data not available | Originated	'	'
Credit Quality Information	'	'
Recorded investment	1,119	1,436
Percentage of loans to aggregate outstanding amount	0.40%	0.50%
Home equity | Data not available | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	231	26,782
Percentage of loans to aggregate outstanding amount	0.10%	10.20%
Other consumer	'	'
Credit Quality Information	'	'
Recorded investment	7,055	7,279
Other consumer | Originated	'	'
Credit Quality Information	'	'
Recorded investment	5,532	6,122
Other consumer | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	1,523	1,157
Other consumer | Pass | Originated	'	'
Credit Quality Information	'	'
Recorded investment	5,528	6,093
Other consumer | Pass | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	1,509	1,157
Other consumer | OAEM | Originated	'	'
Credit Quality Information	'	'
Recorded investment	0	0
Other consumer | OAEM | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	0	0
Other consumer | Substandard | Originated	'	'
Credit Quality Information	'	'
Recorded investment	4	29
Other consumer | Substandard | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	14	0
Other consumer | Doubtful | Originated	'	'
Credit Quality Information	'	'
Recorded investment	0	0
Other consumer | Doubtful | Acquired	'	'
Credit Quality Information	'	'
Recorded investment	$0	$0

Allowance_for_Loan_and_Lease_L4

Allowance for Loan and Lease Losses (Details 3) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Age analysis of past due loans	'	'
Total loans and leases	$4,362,465	$4,175,712
Originated	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	28,288	14,507
Past due 61-90 days	3,884	3,315
Past due Greater than 90 days	3,690	4,263
Past due Total	35,862	22,085
Current	3,511,191	3,094,017
Total loans and leases	3,547,053	3,116,102
Loans past due greater than 90 days and accruing	10	493
Remaining balance of loans or leases on non-accrual	8,245	11,483
Acquired	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	5,837	8,484
Past due 61-90 days	1,998	1,221
Past due Greater than 90 days	14,171	19,887
Past due Total	22,006	29,592
Current	793,406	1,030,018
Total loans and leases	815,412	1,059,610
Loans past due greater than 90 days and accruing	10,903	16,144
Remaining balance of loans or leases on non-accrual	8,256	10,763
Commercial real estate loans	'	'
Age analysis of past due loans	'	'
Total loans and leases	2,203,623	2,005,963
Commercial real estate loans | Originated	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	19,296	6,294
Past due 61-90 days	1,393	876
Past due Greater than 90 days	169	1,423
Past due Total	20,858	8,593
Current	1,748,374	1,449,889
Total loans and leases	1,769,232	1,458,482
Loans past due greater than 90 days and accruing	0	434
Remaining balance of loans or leases on non-accrual	169	3,471
Commercial real estate loans | Acquired	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	1,548	5,649
Past due 61-90 days	496	395
Past due Greater than 90 days	5,939	9,467
Past due Total	7,983	15,511
Current	426,408	531,970
Total loans and leases	434,391	547,481
Loans past due greater than 90 days and accruing	5,010	8,473
Remaining balance of loans or leases on non-accrual	929	4,776
Commercial real estate mortgage	'	'
Age analysis of past due loans	'	'
Total loans and leases	1,461,985	1,301,233
Commercial real estate mortgage | Originated	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	4,896	1,530
Past due 61-90 days	1,393	0
Past due Greater than 90 days	169	435
Past due Total	6,458	1,965
Current	1,105,292	869,587
Total loans and leases	1,111,750	871,552
Loans past due greater than 90 days and accruing	0	434
Remaining balance of loans or leases on non-accrual	169	1,539
Commercial real estate mortgage | Acquired	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	1,221	2,911
Past due 61-90 days	87	0
Past due Greater than 90 days	4,887	7,289
Past due Total	6,195	10,200
Current	344,040	419,481
Total loans and leases	350,235	429,681
Loans past due greater than 90 days and accruing	3,958	6,616
Remaining balance of loans or leases on non-accrual	929	2,475
Multi-family mortgage	'	'
Age analysis of past due loans	'	'
Total loans and leases	627,933	606,533
Multi-family mortgage | Originated	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	14,400	2,410
Past due 61-90 days	0	60
Past due Greater than 90 days	0	988
Past due Total	14,400	3,458
Current	540,155	502,559
Total loans and leases	554,555	506,017
Loans past due greater than 90 days and accruing	0	0
Remaining balance of loans or leases on non-accrual	0	1,932
Multi-family mortgage | Acquired	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	327	2,738
Past due 61-90 days	0	395
Past due Greater than 90 days	1,052	2,178
Past due Total	1,379	5,311
Current	71,999	95,205
Total loans and leases	73,378	100,516
Loans past due greater than 90 days and accruing	1,052	1,857
Remaining balance of loans or leases on non-accrual	0	2,301
Construction	'	'
Age analysis of past due loans	'	'
Total loans and leases	113,705	98,197
Construction | Originated	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	0	2,354
Past due 61-90 days	0	816
Past due Greater than 90 days	0	0
Past due Total	0	3,170
Current	102,927	77,743
Total loans and leases	102,927	80,913
Loans past due greater than 90 days and accruing	0	0
Remaining balance of loans or leases on non-accrual	0	0
Construction | Acquired	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	0	0
Past due 61-90 days	409	0
Past due Greater than 90 days	0	0
Past due Total	409	0
Current	10,369	17,284
Total loans and leases	10,778	17,284
Loans past due greater than 90 days and accruing	0	0
Remaining balance of loans or leases on non-accrual	0	0
Commercial loans	'	'
Age analysis of past due loans	'	'
Total loans and leases	965,610	847,455
Commercial loans | Originated	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	3,155	2,621
Past due 61-90 days	1,633	1,514
Past due Greater than 90 days	2,873	1,644
Past due Total	7,661	5,779
Current	820,147	635,597
Total loans and leases	827,808	641,376
Loans past due greater than 90 days and accruing	0	26
Remaining balance of loans or leases on non-accrual	5,638	5,818
Commercial loans | Acquired	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	2,753	999
Past due 61-90 days	162	198
Past due Greater than 90 days	2,004	4,547
Past due Total	4,919	5,744
Current	132,883	200,335
Total loans and leases	137,802	206,079
Loans past due greater than 90 days and accruing	1,308	3,700
Remaining balance of loans or leases on non-accrual	4,626	3,517
Commercial	'	'
Age analysis of past due loans	'	'
Total loans and leases	407,792	382,277
Commercial | Originated	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	2,288	26
Past due 61-90 days	75	75
Past due Greater than 90 days	842	26
Past due Total	3,205	127
Current	294,479	230,765
Total loans and leases	297,684	230,892
Loans past due greater than 90 days and accruing	0	26
Remaining balance of loans or leases on non-accrual	1,551	1,993
Commercial | Acquired	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	2,707	866
Past due 61-90 days	121	177
Past due Greater than 90 days	1,931	4,353
Past due Total	4,759	5,396
Current	105,349	145,989
Total loans and leases	110,108	151,385
Loans past due greater than 90 days and accruing	1,235	3,503
Remaining balance of loans or leases on non-accrual	4,597	3,461
Equipment financing	'	'
Age analysis of past due loans	'	'
Total loans and leases	513,024	420,991
Equipment financing | Originated	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	867	2,595
Past due 61-90 days	1,558	1,439
Past due Greater than 90 days	2,031	1,618
Past due Total	4,456	5,652
Current	480,874	360,645
Total loans and leases	485,330	366,297
Loans past due greater than 90 days and accruing	0	0
Remaining balance of loans or leases on non-accrual	4,086	3,817
Equipment financing | Acquired	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	46	133
Past due 61-90 days	41	21
Past due Greater than 90 days	73	194
Past due Total	160	348
Current	27,534	54,346
Total loans and leases	27,694	54,694
Loans past due greater than 90 days and accruing	73	197
Remaining balance of loans or leases on non-accrual	29	56
Condominium association	'	'
Age analysis of past due loans	'	'
Total loans and leases	44,794	44,187
Condominium association | Originated	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	0	0
Past due 61-90 days	0	0
Past due Greater than 90 days	0	0
Past due Total	0	0
Current	44,794	44,187
Total loans and leases	44,794	44,187
Loans past due greater than 90 days and accruing	0	0
Remaining balance of loans or leases on non-accrual	1	8
Condominium association | Acquired	'	'
Age analysis of past due loans	'	'
Total loans and leases	0	0
Indirect automobile	'	'
Age analysis of past due loans	'	'
Total loans and leases	400,531	542,344
Indirect automobile | Originated	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	5,407	5,592
Past due 61-90 days	857	923
Past due Greater than 90 days	229	99
Past due Total	6,493	6,614
Current	394,038	535,730
Total loans and leases	400,531	542,344
Loans past due greater than 90 days and accruing	10	1
Remaining balance of loans or leases on non-accrual	259	99
Consumer loans	'	'
Age analysis of past due loans	'	'
Total loans and leases	792,701	779,950
Consumer loans | Originated	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	430	0
Past due 61-90 days	1	2
Past due Greater than 90 days	419	1,097
Past due Total	850	1,099
Current	548,632	472,801
Total loans and leases	549,482	473,900
Loans past due greater than 90 days and accruing	0	32
Remaining balance of loans or leases on non-accrual	2,179	2,095
Consumer loans | Acquired	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	1,536	1,836
Past due 61-90 days	1,340	628
Past due Greater than 90 days	6,228	5,873
Past due Total	9,104	8,337
Current	234,115	297,713
Total loans and leases	243,219	306,050
Loans past due greater than 90 days and accruing	4,585	3,971
Remaining balance of loans or leases on non-accrual	2,701	2,470
Residential mortgage	'	'
Age analysis of past due loans	'	'
Total loans and leases	528,185	511,109
Residential mortgage | Originated	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	201	0
Past due 61-90 days	0	0
Past due Greater than 90 days	415	1,059
Past due Total	616	1,059
Current	410,938	367,036
Total loans and leases	411,554	368,095
Loans past due greater than 90 days and accruing	0	27
Remaining balance of loans or leases on non-accrual	1,713	2,008
Residential mortgage | Acquired	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	271	247
Past due 61-90 days	777	121
Past due Greater than 90 days	5,329	5,266
Past due Total	6,377	5,634
Current	110,254	137,380
Total loans and leases	116,631	143,014
Loans past due greater than 90 days and accruing	4,468	3,650
Remaining balance of loans or leases on non-accrual	1,162	1,796
Home equity	'	'
Age analysis of past due loans	'	'
Total loans and leases	257,461	261,562
Home equity | Originated	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	218	0
Past due 61-90 days	0	0
Past due Greater than 90 days	0	33
Past due Total	218	33
Current	132,178	99,650
Total loans and leases	132,396	99,683
Loans past due greater than 90 days and accruing	0	0
Remaining balance of loans or leases on non-accrual	462	58
Home equity | Acquired	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	1,259	1,582
Past due 61-90 days	552	507
Past due Greater than 90 days	895	607
Past due Total	2,706	2,696
Current	122,359	159,183
Total loans and leases	125,065	161,879
Loans past due greater than 90 days and accruing	117	321
Remaining balance of loans or leases on non-accrual	1,525	658
Other consumer	'	'
Age analysis of past due loans	'	'
Total loans and leases	7,055	7,279
Other consumer | Originated	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	11	0
Past due 61-90 days	1	2
Past due Greater than 90 days	4	5
Past due Total	16	7
Current	5,516	6,115
Total loans and leases	5,532	6,122
Loans past due greater than 90 days and accruing	0	5
Remaining balance of loans or leases on non-accrual	4	29
Other consumer | Acquired	'	'
Age analysis of past due loans	'	'
Past due 31-60 days	6	7
Past due 61-90 days	11	0
Past due Greater than 90 days	4	0
Past due Total	21	7
Current	1,502	1,150
Total loans and leases	1,523	1,157
Loans past due greater than 90 days and accruing	0	0
Remaining balance of loans or leases on non-accrual	$14	$16

Allowance_for_Loan_and_Lease_L5

Allowance for Loan and Lease Losses (Details 4)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
	score
Allowance for loan losses and recorded investment in loans	'	'
Number of days past due, non-accrual status (in days)	'90 days	'
Commercial real estate loans	'	'
Allowance for loan losses and recorded investment in loans	'	'
Number of loan classes within specific portfolio	3	'
Commercial real estate	'	'
Allowance for loan losses and recorded investment in loans	'	'
Percentage of loans to aggregate outstanding amount	33.50%	'
Multi-family	'	'
Allowance for loan losses and recorded investment in loans	'	'
Percentage of loans to aggregate outstanding amount	14.40%	'
Construction	'	'
Allowance for loan losses and recorded investment in loans	'	'
Percentage of loans to aggregate outstanding amount	2.60%	'
Commercial loans	'	'
Allowance for loan losses and recorded investment in loans	'	'
Number of loan classes within specific portfolio	3	'
Commercial	'	'
Allowance for loan losses and recorded investment in loans	'	'
Percentage of loans to aggregate outstanding amount	9.30%	'
Equipment financing	'	'
Allowance for loan losses and recorded investment in loans	'	'
Percentage of loans to aggregate outstanding amount	11.80%	'
Percentage of loans to aggregate outstanding amount in the greater New York/New Jersey Metropolitan area and northeastern states	38.20%	'
Condominium association	'	'
Allowance for loan losses and recorded investment in loans	'	'
Percentage of loans to aggregate outstanding amount	1.00%	'
Indirect automobile	'	'
Allowance for loan losses and recorded investment in loans	'	'
Percentage of loans to aggregate outstanding amount	9.20%	'
Minimum credit score for high data range	700	'
Maximum credit score for middle data range	700	'
Minimum credit score for middle data range	661	'
Maximum credit score for low data range	660	'
Percentage of loans made to borrowers with credit scores below 660	3.10%	3.20%
Consumer loans	'	'
Allowance for loan losses and recorded investment in loans	'	'
Number of loan classes within specific portfolio	3	'
Loans not made, loan to value ratio, minimum (as a percent)	80.00%	'
Consumer loans | Minimum	'	'
Allowance for loan losses and recorded investment in loans	'	'
Number of days past due, non-accrual status (in days)	'90 days	'
Residential	'	'
Allowance for loan losses and recorded investment in loans	'	'
Percentage of loans to aggregate outstanding amount	12.10%	'
Home equity	'	'
Allowance for loan losses and recorded investment in loans	'	'
Percentage of loans to aggregate outstanding amount	5.90%	'
Other consumer	'	'
Allowance for loan losses and recorded investment in loans	'	'
Percentage of loans to aggregate outstanding amount	0.20%	'

Allowance_for_Loan_and_Lease_L6

Allowance for Loan and Lease Losses (Details 5) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Recorded investment in loans and leases by portfolio segment	'		'		'
Loans and Leases Individually Evaluated for Impairment, Portfolio	$22,090,000		$18,859,000		'
Loans and Leases Individually Evaluated for Impairment, Allowance	1,182,000		1,690,000		'
Loans and Leases Collectively Evaluated for Impairment, Portfolio	3,934,555,000		3,640,992,000		'
Loans and Leases Collectively Evaluated for Impairment, Allowance	46,049,000		39,462,000		'
ASC 310-30 Acquired Loans and Leases, Portfolio	405,820,000		515,861,000		'
ASC 310-30 Acquired Loans and Leases, Allowance	1,242,000		0		'
Total loans and leases	4,362,465,000		4,175,712,000		'
Total, Allowance	48,473,000		41,152,000		'
Originated	'		'		'
Impaired Loans and Leases	'		'		'
Recorded investment, loans with no related allowance recorded	7,408,000	[1]	6,274,000	[2]	9,480,000
Recorded investment, loans with related allowance recorded	6,307,000	[1]	9,587,000	[2]	943,000
Recorded investment	13,715,000	[1]	15,861,000	[2]	10,423,000
Recorded investment, nonaccrual loans	5,800,000		8,800,000		'
Unpaid principal balance with no related allowance recorded	7,395,000		6,297,000		10,440,000
Unpaid principal balance with related allowance recorded	6,289,000		9,711,000		958,000
Unpaid principal balance	13,684,000		16,008,000		11,398,000
Related allowance	1,182,000		1,540,000		225,000
Average recorded investment with no related allowance recorded	7,518,000		7,829,000		9,625,000
Average recorded investment with related allowance recorded	6,455,000		7,453,000		1,117,000
Average recorded investment	13,973,000		15,282,000		10,742,000
Interest income recognized with no related allowance recorded	266,000		554,000		372,000
Interest income recognized with related allowance recorded	169,000		484,000		65,000
Interest income recognized, Total	435,000		1,038,000		437,000
Recorded investment in loans and leases by portfolio segment	'		'		'
Total loans and leases	3,547,053,000		3,116,102,000		'
Acquired	'		'		'
Impaired Loans and Leases	'		'		'
Recorded investment, loans with no related allowance recorded	17,197,000	[3]	28,513,000	[4]	'
Recorded investment, loans with related allowance recorded	2,294,000	[3]	786,000	[4]	'
Recorded investment	19,491,000	[3]	29,299,000	[4]	'
Recorded investment, nonaccrual loans	10,900,000		21,500,000		'
Unpaid principal balance with no related allowance recorded	18,367,000		30,290,000		'
Unpaid principal balance with related allowance recorded	2,358,000		805,000		'
Unpaid principal balance	20,725,000		31,095,000		'
Related allowance	291,000		150,000		'
Average recorded investment with no related allowance recorded	16,177,000		15,191,000		'
Average recorded investment with related allowance recorded	3,342,000		475,000		'
Average recorded investment	19,519,000		15,666,000		'
Interest income recognized with no related allowance recorded	400,000		0		'
Interest income recognized with related allowance recorded	47,000		0		'
Interest income recognized, Total	447,000		0		'
Recorded investment in loans and leases by portfolio segment	'		'		'
Total loans and leases	815,412,000		1,059,610,000		'
Commercial real estate loans	'		'		'
Recorded investment in loans and leases by portfolio segment	'		'		'
Loans and Leases Individually Evaluated for Impairment, Portfolio	6,269,000		5,576,000		'
Loans and Leases Individually Evaluated for Impairment, Allowance	184,000		316,000		'
Loans and Leases Collectively Evaluated for Impairment, Portfolio	1,910,645,000		1,652,231,000		'
Loans and Leases Collectively Evaluated for Impairment, Allowance	22,282,000		19,702,000		'
ASC 310-30 Acquired Loans and Leases, Portfolio	286,709,000		348,156,000		'
ASC 310-30 Acquired Loans and Leases, Allowance	556,000		0		'
Total loans and leases	2,203,623,000		2,005,963,000		'
Total, Allowance	23,022,000		20,018,000		'
Commercial real estate loans | Originated	'		'		'
Impaired Loans and Leases	'		'		'
Recorded investment, loans with no related allowance recorded	2,009,000	[1]	2,051,000	[2]	2,902,000
Recorded investment, loans with related allowance recorded	1,466,000	[1]	2,517,000	[2]	'
Unpaid principal balance with no related allowance recorded	2,009,000		2,051,000		3,140,000
Unpaid principal balance with related allowance recorded	1,466,000		2,516,000		'
Related allowance	184,000		241,000		'
Average recorded investment with no related allowance recorded	2,184,000		2,547,000		2,834,000
Average recorded investment with related allowance recorded	1,464,000		1,142,000		'
Interest income recognized with no related allowance recorded	92,000		243,000		119,000
Interest income recognized with related allowance recorded	43,000		79,000		'
Recorded investment in loans and leases by portfolio segment	'		'		'
Total loans and leases	1,769,232,000		1,458,482,000		'
Commercial real estate loans | Acquired	'		'		'
Impaired Loans and Leases	'		'		'
Recorded investment, loans with no related allowance recorded	9,176,000	[3]	17,918,000	[4]	'
Recorded investment, loans with related allowance recorded	1,274,000	[3]	673,000	[4]	'
Unpaid principal balance with no related allowance recorded	10,082,000		19,129,000		'
Unpaid principal balance with related allowance recorded	1,291,000		684,000		'
Related allowance	122,000		75,000		'
Average recorded investment with no related allowance recorded	9,639,000		9,071,000		'
Average recorded investment with related allowance recorded	2,765,000		366,000		'
Interest income recognized with no related allowance recorded	251,000		0		'
Interest income recognized with related allowance recorded	42,000		0		'
Recorded investment in loans and leases by portfolio segment	'		'		'
Total loans and leases	434,391,000		547,481,000		'
Commercial	'		'		'
Recorded investment in loans and leases by portfolio segment	'		'		'
Loans and Leases Individually Evaluated for Impairment, Portfolio	11,512,000		8,046,000		'
Loans and Leases Individually Evaluated for Impairment, Allowance	675,000		778,000		'
Loans and Leases Collectively Evaluated for Impairment, Portfolio	914,739,000		774,366,000		'
Loans and Leases Collectively Evaluated for Impairment, Allowance	14,293,000		9,877,000		'
ASC 310-30 Acquired Loans and Leases, Portfolio	39,359,000		65,043,000		'
ASC 310-30 Acquired Loans and Leases, Allowance	252,000		0		'
Total loans and leases	965,610,000		847,455,000		'
Total, Allowance	15,220,000		10,655,000		'
Commercial | Originated	'		'		'
Impaired Loans and Leases	'		'		'
Recorded investment, loans with no related allowance recorded	4,410,000	[1]	3,032,000	[2]	3,341,000
Recorded investment, loans with related allowance recorded	2,393,000	[1]	3,422,000	[2]	604,000
Unpaid principal balance with no related allowance recorded	4,399,000		3,059,000		4,063,000
Unpaid principal balance with related allowance recorded	2,383,000		3,559,000		619,000
Related allowance	675,000		703,000		190,000
Average recorded investment with no related allowance recorded	4,257,000		3,159,000		2,938,000
Average recorded investment with related allowance recorded	1,781,000		3,393,000		774,000
Interest income recognized with no related allowance recorded	144,000		181,000		94,000
Interest income recognized with related allowance recorded	29,000		305,000		58,000
Recorded investment in loans and leases by portfolio segment	'		'		'
Total loans and leases	827,808,000		641,376,000		'
Commercial | Acquired	'		'		'
Impaired Loans and Leases	'		'		'
Recorded investment, loans with no related allowance recorded	6,988,000	[3]	7,329,000	[4]	'
Recorded investment, loans with related allowance recorded	1,020,000	[3]	113,000	[4]	'
Unpaid principal balance with no related allowance recorded	7,248,000		7,782,000		'
Unpaid principal balance with related allowance recorded	1,067,000		121,000		'
Related allowance	169,000		75,000		'
Average recorded investment with no related allowance recorded	5,205,000		3,801,000		'
Average recorded investment with related allowance recorded	577,000		109,000		'
Interest income recognized with no related allowance recorded	129,000		0		'
Interest income recognized with related allowance recorded	5,000		0		'
Recorded investment in loans and leases by portfolio segment	'		'		'
Total loans and leases	137,802,000		206,079,000		'
Indirect automobile	'		'		'
Recorded investment in loans and leases by portfolio segment	'		'		'
Loans and Leases Individually Evaluated for Impairment, Portfolio	0		0		'
Loans and Leases Individually Evaluated for Impairment, Allowance	0		0		'
Loans and Leases Collectively Evaluated for Impairment, Portfolio	400,531,000		542,344,000		'
Loans and Leases Collectively Evaluated for Impairment, Allowance	3,924,000		5,304,000		'
ASC 310-30 Acquired Loans and Leases, Portfolio	0		0		'
ASC 310-30 Acquired Loans and Leases, Allowance	0		0		'
Total loans and leases	400,531,000		542,344,000		'
Total, Allowance	3,924,000		5,304,000		'
Indirect automobile | Originated	'		'		'
Impaired Loans and Leases	'		'		'
Recorded investment, loans with no related allowance recorded	'		'		111,000
Unpaid principal balance with no related allowance recorded	'		'		111,000
Average recorded investment with no related allowance recorded	'		'		100,000
Interest income recognized with no related allowance recorded	'		'		0
Recorded investment in loans and leases by portfolio segment	'		'		'
Total loans and leases	400,531,000		542,344,000		'
Consumer loans	'		'		'
Recorded investment in loans and leases by portfolio segment	'		'		'
Loans and Leases Individually Evaluated for Impairment, Portfolio	4,309,000		5,237,000		'
Loans and Leases Individually Evaluated for Impairment, Allowance	323,000		596,000		'
Loans and Leases Collectively Evaluated for Impairment, Portfolio	708,640,000		672,051,000		'
Loans and Leases Collectively Evaluated for Impairment, Allowance	2,618,000		1,949,000		'
ASC 310-30 Acquired Loans and Leases, Portfolio	79,752,000		102,662,000		'
ASC 310-30 Acquired Loans and Leases, Allowance	434,000		0		'
Total loans and leases	792,701,000		779,950,000		'
Total, Allowance	3,375,000		2,545,000		'
Consumer loans | Originated	'		'		'
Impaired Loans and Leases	'		'		'
Recorded investment, loans with no related allowance recorded	989,000	[1]	1,191,000	[2]	3,126,000
Recorded investment, loans with related allowance recorded	2,448,000	[1]	3,648,000	[2]	339,000
Unpaid principal balance with no related allowance recorded	987,000		1,187,000		3,126,000
Unpaid principal balance with related allowance recorded	2,440,000		3,636,000		339,000
Related allowance	323,000		596,000		35,000
Average recorded investment with no related allowance recorded	1,077,000		2,123,000		3,753,000
Average recorded investment with related allowance recorded	3,210,000		2,918,000		343,000
Interest income recognized with no related allowance recorded	30,000		130,000		159,000
Interest income recognized with related allowance recorded	97,000		100,000		7,000
Recorded investment in loans and leases by portfolio segment	'		'		'
Total loans and leases	549,482,000		473,900,000		'
Consumer loans | Acquired	'		'		'
Impaired Loans and Leases	'		'		'
Recorded investment, loans with no related allowance recorded	1,033,000	[3]	3,266,000	[4]	'
Recorded investment, loans with related allowance recorded	0	[3]	0	[4]	'
Unpaid principal balance with no related allowance recorded	1,037,000		3,379,000		'
Unpaid principal balance with related allowance recorded	0		0		'
Related allowance	0		0		'
Average recorded investment with no related allowance recorded	1,333,000		2,319,000		'
Average recorded investment with related allowance recorded	0		0		'
Interest income recognized with no related allowance recorded	20,000		0		'
Interest income recognized with related allowance recorded	0		0		'
Recorded investment in loans and leases by portfolio segment	'		'		'
Total loans and leases	243,219,000		306,050,000		'
Unallocated	'		'		'
Recorded investment in loans and leases by portfolio segment	'		'		'
Loans and Leases Individually Evaluated for Impairment, Portfolio	0		0		'
Loans and Leases Individually Evaluated for Impairment, Allowance	0		0		'
Loans and Leases Collectively Evaluated for Impairment, Portfolio	0		0		'
Loans and Leases Collectively Evaluated for Impairment, Allowance	2,932,000		2,630,000		'
ASC 310-30 Acquired Loans and Leases, Portfolio	0		0		'
ASC 310-30 Acquired Loans and Leases, Allowance	0		0		'
Total loans and leases	0		0		'
Total, Allowance	$2,932,000		$2,630,000		'
[1]	Includes nonaccrual loans of $5.8 million At DecemberB 31, 2013B Year Ended DecemberB 31, 2013B RecordedInvestment (1)B UnpaidPrincipalBalanceB RelatedAllowanceB AverageRecordedInvestmentB InterestIncomeRecognizedB (In Thousands)Acquired: With no related allowance recorded: Commercial real estate$9,176B $10,082B $bB $9,639B $251Commercial6,988B 7,248B bB 5,205B 129Consumer1,033B 1,037B bB 1,333B 20B 17,197B 18,367B bB 16,177B 400With an allowance recorded: Commercial real estate1,274B 1,291B 122B 2,765B 42Commercial1,020B 1,067B 169B 577B 5ConsumerbB bB bB bB bB 2,294B 2,358B 291B 3,342B 47Total$19,491B $20,725B $291B $19,519B $447
[2]	Includes nonaccrual loans of $8.8 million
[3]	Includes nonaccrual loans of $10.9 million
[4]	Includes nonaccrual loans of $21.5 million

Allowance_for_Loan_and_Lease_L7

Allowance for Loan and Lease Losses (Details 6) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Troubled Debt Restructured Loans and Leases	'	'	'
Recorded Investment, At modification	$6,058,000	$7,216,000	$4,520,000
Financial impact of modification of performing and nonperforming loans	800,000	0	'
Loans with more than one modification	490,000	3,857,000	2,653,000
Originated	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Nonaccrual loans and leases	8,245,000	11,483,000	'
Acquired	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Nonaccrual loans and leases	8,256,000	10,763,000	'
Extended maturity	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Recorded Investment, At modification	3,841,000	1,478,000	1,136,000
Loans with more than one modification	490,000	0	78,000
Adjusted principal	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Recorded Investment, At modification	908,000	2,185,000	1,456,000
Loans with more than one modification	0	3,857,000	1,471,000
Adjusted interest rate	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Recorded Investment, At modification	755,000	1,715,000	0
Loans with more than one modification	0	0	353,000
Combination maturity, principal, interest rate	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Recorded Investment, At modification	554,000	1,838,000	1,928,000
Loans with more than one modification	0	0	751,000
Commercial real estate | Originated	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	1	2	2
Recorded Investment, At modification	1,039,000	867,000	1,171,000
Recorded Investment, At end of period	0	854,000	1,170,000
Specific Allowance for Loan and Lease Losses	0	33,000	28,000
Nonaccrual loans and leases	0	513,000	0
Commercial real estate | Acquired	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	1	1	1
Recorded Investment, At modification	737,000	3,145,000	1,725,000
Recorded Investment, At end of period	727,000	3,208,000	1,609,000
Specific Allowance for Loan and Lease Losses	0	0	0
Nonaccrual loans and leases	0	0	1,608,000
Commercial real estate | Defaulted | Originated	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	0	2	0
Recorded Investment, At modification	0	1,288,000	0
Commercial real estate | Defaulted | Acquired	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	0	0	0
Recorded Investment, At modification	0	0	0
Multi-family mortgage | Originated	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	'	'	1
Recorded Investment, At modification	'	'	29,000
Recorded Investment, At end of period	'	'	29,000
Specific Allowance for Loan and Lease Losses	'	'	0
Nonaccrual loans and leases	'	'	29,000
Multi-family mortgage | Acquired	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	'	'	0
Recorded Investment, At modification	'	'	0
Recorded Investment, At end of period	'	'	0
Specific Allowance for Loan and Lease Losses	'	'	0
Nonaccrual loans and leases	'	'	0
Multi-family mortgage | Defaulted | Originated	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	'	'	1
Recorded Investment, At modification	'	'	29,000
Multi-family mortgage | Defaulted | Acquired	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	'	'	0
Recorded Investment, At modification	'	'	0
Commercial | Originated	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	2	3	1
Recorded Investment, At modification	926,000	3,942,000	66,000
Recorded Investment, At end of period	918,000	2,086,000	66,000
Specific Allowance for Loan and Lease Losses	0	316,000	0
Nonaccrual loans and leases	0	1,993,000	0
Commercial | Acquired	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	6	2	0
Recorded Investment, At modification	3,209,000	1,229,000	0
Recorded Investment, At end of period	3,135,000	1,163,000	0
Specific Allowance for Loan and Lease Losses	0	0	0
Nonaccrual loans and leases	1,335,000	478,000	0
Commercial | Defaulted | Originated	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	0	1	0
Recorded Investment, At modification	0	44,000	0
Commercial | Defaulted | Acquired	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	1	0	0
Recorded Investment, At modification	1,335,000	0	0
Equipment financing | Originated	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	5	8	16
Recorded Investment, At modification	1,557,000	2,138,000	1,819,000
Recorded Investment, At end of period	1,415,000	2,038,000	1,710,000
Specific Allowance for Loan and Lease Losses	77,000	110,000	173,000
Nonaccrual loans and leases	861,000	793,000	524,000
Equipment financing | Acquired	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	0	0	0
Recorded Investment, At modification	0	0	0
Recorded Investment, At end of period	0	0	0
Specific Allowance for Loan and Lease Losses	0	0	0
Nonaccrual loans and leases	0	0	0
Equipment financing | Defaulted | Originated	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	2	6	3
Recorded Investment, At modification	371,000	1,240,000	365,000
Equipment financing | Defaulted | Acquired	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	0	0	0
Recorded Investment, At modification	0	0	0
Residential mortgage | Originated	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	1	6	10
Recorded Investment, At modification	415,000	2,422,000	1,942,000
Recorded Investment, At end of period	353,000	1,724,000	1,937,000
Specific Allowance for Loan and Lease Losses	0	315,000	190,000
Nonaccrual loans and leases	353,000	294,000	243,000
Residential mortgage | Acquired	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	0	0	1
Recorded Investment, At modification	0	0	677,000
Recorded Investment, At end of period	0	0	652,000
Specific Allowance for Loan and Lease Losses	0	0	0
Nonaccrual loans and leases	0	0	0
Residential mortgage | Defaulted | Originated	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	0	3	2
Recorded Investment, At modification	0	763,000	491,000
Residential mortgage | Defaulted | Acquired	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	0	0	0
Recorded Investment, At modification	0	0	0
Total | Originated	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	9	19	30
Recorded Investment, At modification	3,937,000	9,369,000	5,027,000
Recorded Investment, At end of period	2,686,000	6,702,000	4,912,000
Specific Allowance for Loan and Lease Losses	77,000	774,000	391,000
Nonaccrual loans and leases	1,214,000	3,593,000	796,000
Total | Acquired	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	7	3	2
Recorded Investment, At modification	3,946,000	4,374,000	2,402,000
Recorded Investment, At end of period	3,862,000	4,371,000	2,261,000
Specific Allowance for Loan and Lease Losses	0	0	0
Nonaccrual loans and leases	1,335,000	478,000	1,608,000
Total | Defaulted | Originated	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	2	12	6
Recorded Investment, At modification	371,000	3,335,000	885,000
Total | Defaulted | Acquired	'	'	'
Troubled Debt Restructured Loans and Leases	'	'	'
Number of loans	1	0	0
Recorded Investment, At modification	$1,335,000	$0	$0

Premises_and_Equipment_Details

Premises and Equipment (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Premises and Equipment	'	'	'
Premises and Equipment, gross amount	$124,925,000	$109,776,000	'
Accumulated depreciation and amortization	44,420,000	38,985,000	'
Premises and Equipment, net amount	80,505,000	70,791,000	'
Depreciation and amortization expense	6,500,000	4,000,000	2,100,000
Land	'	'	'
Premises and Equipment	'	'	'
Premises and Equipment, gross amount	7,481,000	7,553,000	'
Office building and improvements	'	'	'
Premises and Equipment	'	'	'
Premises and Equipment, gross amount	75,271,000	67,672,000	'
Furniture, fixtures and equipment	'	'	'
Premises and Equipment	'	'	'
Premises and Equipment, gross amount	25,633,000	22,537,000	'
Software	'	'	'
Premises and Equipment	'	'	'
Premises and Equipment, gross amount	5,018,000	5,063,000	'
Core processing system	'	'	'
Premises and Equipment	'	'	'
Premises and Equipment, gross amount	$11,522,000	$6,951,000	'
Estimated Useful Life (in years)	'7 years 6 months	'	'
Minimum | Office building and improvements	'	'	'
Premises and Equipment	'	'	'
Estimated Useful Life (in years)	'10 years	'	'
Minimum | Furniture, fixtures and equipment	'	'	'
Premises and Equipment	'	'	'
Estimated Useful Life (in years)	'3 years	'	'
Minimum | Software	'	'	'
Premises and Equipment	'	'	'
Estimated Useful Life (in years)	'3 years	'	'
Maximum | Office building and improvements	'	'	'
Premises and Equipment	'	'	'
Estimated Useful Life (in years)	'40 years	'	'
Maximum | Furniture, fixtures and equipment	'	'	'
Premises and Equipment	'	'	'
Estimated Useful Life (in years)	'10 years	'	'
Maximum | Software	'	'	'
Premises and Equipment	'	'	'
Estimated Useful Life (in years)	'7 years	'	'

Goodwill_and_Other_Intangible_2

Goodwill and Other Intangible Assets (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Goodwill [Roll Forward]	'	'	'
Balance at beginning of year	$137,890	$45,799	$43,241
Additions	0	93,145	2,558
Adjustments to original goodwill	0	-1,054	0
Goodwill balance at end of period	$137,890	$137,890	$45,799

Goodwill_and_Other_Intangible_3

Goodwill and Other Intangible Assets (Details 2) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Other intangibe assets:	'	'
Gross amount	$39,782	$39,782
Accumulated amortization	22,895	18,272
Carrying Amount	16,887	21,510
Core deposit intangible	'	'
Other intangibe assets:	'	'
Gross amount	36,172	36,172
Accumulated amortization	20,395	16,399
Carrying Amount	15,777	19,773
Weighted-average amortziation period	'11 years	'
Trade name	'	'
Other intangibe assets:	'	'
Gross amount	1,600	1,600
Accumulated amortization	511	267
Carrying Amount	1,089	1,333
Trust Relationship [Member]	'	'
Other intangibe assets:	'	'
Gross amount	1,568	1,568
Accumulated amortization	1,547	1,164
Carrying Amount	21	404
Weighted-average amortziation period	'1 year	'
Other Intangible Assets [Member]	'	'
Other intangibe assets:	'	'
Gross amount	442	442
Accumulated amortization	442	442
Carrying Amount	$0	$0

Goodwill_and_Other_Intangible_4

Goodwill and Other Intangible Assets (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Indefinite-lived Intangible Assets [Line Items]	'	'	'
Impairment losses relating to other acquisition-related intangible assets	$0	$0	$0
Trade Names [Member]	'	'	'
Indefinite-lived Intangible Assets [Line Items]	'	'	'
Indefinite-lived intangible assets	$1,100,000	'	'

Goodwill_and_Other_Intangible_5

Goodwill and Other Intangible Assets (Details 4) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified
Goodwill and Intangible Assets Disclosure [Abstract]	'
2014	$3,124
2015	2,868
2016	2,457
2017	1,858
2018	1,836
Thereafter	3,655
Carrying amount	$15,798

Other_Assets_Details

Other Assets (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
	policy	policy
BankRI	'	'
Other Assets	'	'
Number of policies owned	9	9
Net cash surrender value	$34.70	$33.70
First Ipswich Bancorp:	'	'
Other Assets	'	'
Number of policies owned	2	2
Net cash surrender value	$0.70	$0.70

Other_Assets_Details_2

Other Assets (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
	project
Investment in housing programs	'	'	'
Maximum percentage of outstanding equity interest that can be invested by the entity in any single project	50.00%	'	'
Investments in affordable housing projects included in other assets	$77,180,000	$83,281,000	'
Unfunded commitments related to affordable housing projects included in other liabilities	1,000,000	700,000	800,000
Affordable housing project	'	'	'
Investment in housing programs	'	'	'
Number of investments	7	'	'
Number of investments acquired during period	2	'	'
Payments to acquire investments	3,300,000	'	'
Investments in affordable housing projects included in other assets	10,301,000	9,167,000	6,712,000
Unfunded commitments related to affordable housing projects included in other liabilities	2,904,000	4,291,000	2,864,000
Loss from investments in affordable housing projects	1,812,000	694,000	671,000
Reduction in tax expense due to affordable housing tax credits	$1,058,000	$806,000	$464,000

Deposits_Details

Deposits (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Deposits [Abstract]	'	'	'
Demand checking accounts	$707,023,000	$623,274,000	'
NOW accounts	210,602,000	212,858,000	'
Savings accounts	494,734,000	515,367,000	'
Money market accounts	1,487,979,000	1,253,819,000	'
Total core deposit accounts	2,900,338,000	2,605,318,000	'
Certificate of deposit accounts maturing:	'	'	'
Within six months	381,986,000	392,138,000	'
After six months but within 1 year	312,005,000	359,510,000	'
After 1 year but within 2 years	141,518,000	159,747,000	'
After 2 years but within 3 years	45,965,000	34,392,000	'
After 3 years but within 4 years	26,046,000	37,813,000	'
After 4 years but within 5 years	26,810,000	27,341,000	'
After 5 Years	338,000	0	'
Total certificate of deposit accounts	934,668,000	1,010,941,000	'
Total deposits	3,835,006,000	3,616,259,000	'
Weighted Average Rate of deposit accounts	'	'	'
Demand checking accounts (as a percent)	0.00%	0.00%	'
NOW accounts (as a percent)	0.07%	0.09%	'
Savings accounts (as a percent)	0.25%	0.39%	'
Money market savings accounts (as a percent)	0.54%	0.63%	'
Total transaction deposit accounts (as a percent)	0.32%	0.39%	'
Weighted Average Rate of certificate of deposit accounts maturing:	'	'	'
Within six months (as a percent)	0.72%	0.91%	'
After six months but within 1 year (as a percent)	0.82%	0.95%	'
After 1 year but within 2 years (as a percent)	1.09%	1.09%	'
After 2 years but within 3 years (as a percent)	1.91%	2.05%	'
After 3 years but within 4 years (as a percent)	1.65%	2.08%	'
After 4 years but within 5 years (as a percent)	1.33%	1.65%	'
After 5 years (as a percent)	1.15%	0.00%	'
Total certificate of deposit accounts (as a percent)	0.91%	1.06%	'
Total of weighted average rate of deposits (as a percent)	0.47%	0.58%	'
Threshold for disclosure of time deposit issued amounts	100,000	100,000	'
Time Deposits, $100,000 or More	424,700,000	437,900,000	'
Interest-bearing deposits:	'	'	'
NOW accounts	173,000	209,000	216,000
Savings accounts	1,288,000	1,726,000	942,000
Money market savings accounts	8,220,000	8,773,000	7,626,000
Certificate of deposit accounts	9,092,000	10,724,000	10,973,000
Total interest-bearing deposit	18,773,000	21,432,000	19,757,000
Deposits pledged as collateral	$62,400,000	$86,500,000	'

Borrowed_Funds_Details

Borrowed Funds (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Borrowed funds	'	'	'
Total borrowed funds	$812,555,000	$853,969,000	'
Total interest expense on borrowed funds	11,393,000	14,400,000	10,579,000
Securities available-for-sale and loans pledged as collateral	1,600,000,000	1,800,000,000	'
FHLBB advances	'	'	'
Borrowed funds	'	'	'
Total borrowed funds	768,773,000	790,865,000	'
Total interest expense on borrowed funds	10,886,000	13,685,000	10,454,000
Repurchase agreements	'	'	'
Borrowed funds	'	'	'
Total borrowed funds	34,619,000	51,013,000	'
Total interest expense on borrowed funds	68,000	137,000	125,000
Subordinated debenture	'	'	'
Borrowed funds	'	'	'
Total borrowed funds	9,163,000	12,091,000	'
Total interest expense on borrowed funds	$439,000	$578,000	$0

Borrowed_Funds_Details_2

Borrowed Funds (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Amount	'	'
Within 1 year	$186,035,000	$363,485,000
Over 1 year to 2 years	283,000,000	46,178,000
Over 2 years to 3 years	92,971,000	108,000,000
Over 3 years to 4 years	147,198,000	64,330,000
Over 4 years to 5 years	36,625,000	149,032,000
Over 5 years	22,944,000	59,840,000
Total	768,773,000	790,865,000
Callable Amount	'	'
Within 1 year	0	17,000,000
Over 1 year to 2 years	0	0
Over 2 years to 3 years	32,094,000	0
Over 3 years to 4 years	118,698,000	30,000,000
Over 4 years to 5 years	10,071,000	112,000,000
Over 5 years	0	10,000,000
Total	160,863,000	169,000,000
Weighted average rate, advances from the FHLB	'	'
Within 1 year (as a percent)	0.71%	1.32%
Over 1 year to 2 years (as a percent)	0.79%	2.14%
Over 2 years to 3 years (as a percent)	2.45%	1.00%
Over 3 years to 4 years (as a percent)	3.86%	3.24%
Over 4 years to 5 years (as a percent)	2.51%	3.86%
Over 5 years (as a percent)	3.70%	3.00%
Weighted average interest rate of total advances from the FHLB (as a percent)	1.71%	2.06%
Qualifying collateral available for Federal Home Loan Bank borrowings	1,600,000,000	'
Total available borrowing capacity from Federal Home Loan Bank	1,000,000,000	'
Outstanding at end of year	812,555,000	853,969,000
Repurchase agreements	'	'
Weighted average rate, advances from the FHLB	'	'
Outstanding at end of year	34,619,000	51,013,000
Average outstanding for the year	38,784,000	46,623,000
Maximum outstanding at any month-end	$48,544,000	$51,013,000
Weighted average rate at end of year	0.17%	0.15%
Weighted average rate paid for the year	0.17%	0.13%

Borrowed_Funds_Details_3

Borrowed Funds (Details 3) (USD $)

3 Months Ended

12 Months Ended

12 Months Ended

Mar. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

debenture

Subordinated debenture

Subordinated debenture

Subordinated debenture mature February 22, 2031

Subordinated debenture mature February 22, 2031

Subordinated debenture mature June 26, 2033

Subordinated debenture mature June 26, 2033

Subordinated debenture mature June 26, 2033

Subordinated debenture mature June 26, 2033

Subordinated debenture mature March 17, 2034

Subordinated debenture mature March 17, 2034

Subordinated debenture mature March 17, 2034

Subordinated debenture mature March 17, 2034

LIBOR [Member]

LIBOR [Member]

LIBOR [Member]

LIBOR [Member]

BankRI

Bancorp Rhode Island, Inc.

BankRI

BankRI

Bancorp Rhode Island, Inc.

Bancorp Rhode Island, Inc.

BankRI

BankRI

Bancorp Rhode Island, Inc.

Bancorp Rhode Island, Inc.

Subordinated debenture mature June 26, 2033

Subordinated debenture mature June 26, 2033

Subordinated debenture mature March 17, 2034

Subordinated debenture mature March 17, 2034

Bancorp Rhode Island, Inc.

Bancorp Rhode Island, Inc.

Bancorp Rhode Island, Inc.

Bancorp Rhode Island, Inc.

Borrowed funds

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of subordinated debentures

'

3

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Subordinated debenture called

$3,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Fixed interest rate

'

'

'

'

'

'

10.20%

'

'

'

'

'

'

'

'

'

'

'

'

Variable interest rate spread (as a percent)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3.10%

3.10%

2.79%

2.79%

Reference rate for variable interest rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'three-month LIBOR

'three-month LIBOR

'three-month LIBOR

'three-month LIBOR

Fair Market Rate at acquisition

'

'

'

'

'

3.00%

'

6.45%

6.45%

'

'

6.45%

6.45%

'

'

'

'

'

'

Total borrowed funds

'

$812,555,000

$853,969,000

$9,163,000

$12,091,000

'

$3,000,000

'

'

$4,666,000

$4,641,000

'

'

$4,497,000

$4,450,000

'

'

'

'

Commitments_and_Contingencies_1

Commitments and Contingencies (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Loan commitments	'	'
Unadvanced portion of loans	$592,782,000	$299,523,000
Unused lines of credit:	'	'
Home equity	205,665,000	165,936,000
Other consumer	1,035,000	4,017,000
Other commercial	0	965,000
Unused letters of credit:	'	'
Financial standby letters of credit	20,410,000	19,887,000
Performance standby letters of credit	2,989,000	2,916,000
Commercial and similar letters of credit	440,000	112,000
Back-to-back interest rate swaps	22,418,000	33,221,000
Unfunded credit commitments liability	1,000,000	700,000
Fair value of interest rate swap assets	800,000	1,300,000
Fair value of interest rate swap liabilities	900,000	1,400,000
Commercial real estate mortgage loans	'	'
Loan commitments	'	'
Commitments to originate loans and leases	48,973,000	158,768,000
Commercial	'	'
Loan commitments	'	'
Commitments to originate loans and leases	143,252,000	116,235,000
Residential mortgage	'	'
Loan commitments	'	'
Commitments to originate loans and leases	$8,027,000	$8,926,000

Commitments_and_Contingencies_2

Commitments and Contingencies (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Summary of future minimum rental payments under noncancellable operating leases year ending December 31	'	'	'
2014	$4,936,000	'	'
2015	4,740,000	'	'
2016	4,500,000	'	'
2017	4,030,000	'	'
2018	3,392,000	'	'
Thereafter	12,431,000	'	'
Total	34,029,000	'	'
Total rental expense	5,200,000	4,500,000	2,700,000
Rental income	$300,000	'	'

Earnings_per_Share_Details

Earnings per Share (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Basic EPS Computation, Numerator:	'	'	'	'	'	'	'	'	'	'	'
Net income	$7,654	$9,429	$9,490	$8,813	$11,863	$11,401	$7,529	$6,349	$35,386	$37,142	$27,600
Basic EPS Computation, Denominator:	'	'	'	'	'	'	'	'	'	'	'
Weighted average shares outstanding	69,862,175	69,830,953	69,774,703	69,762,784	69,742,225	69,716,283	69,677,656	69,664,619	69,808,164	69,702,417	58,633,627
Basic EPS (in dollars per share)	$0.11	$0.14	$0.14	$0.13	$0.17	$0.16	$0.11	$0.09	$0.51	$0.53	$0.47
Diluted EPS Computation, Numerator:	'	'	'	'	'	'	'	'	'	'	'
Net income	$7,654	$9,429	$9,490	$8,813	$11,863	$11,401	$7,529	$6,349	$35,386	$37,142	$27,600
Diluted EPS Computation, Denominator:	'	'	'	'	'	'	'	'	'	'	'
Weighted average shares outstanding	69,862,175	69,830,953	69,774,703	69,762,784	69,742,225	69,716,283	69,677,656	69,664,619	69,808,164	69,702,417	58,633,627
Effect of dilutive securities (in shares)	'	'	'	'	'	'	'	'	75,760	43,839	2,804
Adjusted weighted average shares outstanding	69,951,683	69,913,765	69,833,541	69,830,630	69,799,324	69,754,473	69,715,890	69,665,873	69,883,924	69,746,256	58,636,431
Diluted EPS (in dollars per share)	$0.11	$0.13	$0.14	$0.13	$0.17	$0.16	$0.11	$0.09	$0.51	$0.53	$0.47

Earnings_per_Share_Earnings_pe

Earnings per Share Earnings per Share (Details 2) (Details) (Bancorp Rhode Island, Inc.:)	0 Months Ended
In Millions, unless otherwise specified	Jan. 02, 2012	Jan. 03, 2012
Bancorp Rhode Island, Inc.:	'	'
Acquisitions	'	'
Shares of common stock issued as partial consideration for acquisition	11	11

Comprehensive_Income_Details

Comprehensive Income (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Changes in accumulated other comprehensive (loss) income by component, net of tax	'	'	'
Balance at the beginning of the period	$3,483	$1,963	$2,348
Other comprehensive (loss) income	-11,398	1,520	-385
Balance at the end of the period	-7,915	3,483	1,963
Investment Securities Available-for-Sale	'	'	'
Changes in accumulated other comprehensive (loss) income by component, net of tax	'	'	'
Balance at the beginning of the period	3,358	1,834	2,185
Other comprehensive (loss) income	-11,690	1,524	-351
Balance at the end of the period	-8,332	3,358	1,834
Postretirement Benefits	'	'	'
Changes in accumulated other comprehensive (loss) income by component, net of tax	'	'	'
Balance at the beginning of the period	125	129	163
Other comprehensive (loss) income	292	-4	-34
Balance at the end of the period	$417	$125	$129

Derivatives_and_Hedging_Activi2

Derivatives and Hedging Activities (Details) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012
Derivatives and Hedging Activities	'		'
Number of interest-rate swaps	8		10
Asset Derivatives	'		'
Asset derivatives	$825,000		$1,317,000
Liability Derivatives	'		'
Liability derivatives	856,000		1,380,000
Loss Recognized in Income on Derivatives	'		'
Estimated net credit risk exposure	31,200		100,000
Collateral posted	2,800,000		500,000
Interest Rate Swap [Member]	'		'
Derivatives and Hedging Activities	'		'
Notional amount of interest-rate swaps	22,400,000		33,200,000
Derivatives not designed as hedging instruments | Interest-rate products	'		'
Asset Derivatives	'		'
Asset derivatives	'		1,317,000
Liability Derivatives	'		'
Liability derivatives	'		1,380,000
Loss Recognized in Income on Derivatives	'		'
Loss Recognized in Income on Derivatives	$32,000	[1]	$24,000	[1]
[1]	The amount of loss recognized in income represents changes related to the fair value of the interest rate products.

Comprehensive_Income_Details_2

Comprehensive Income (Details 2) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Provision for income taxes	($4,325)	($4,645)	($5,382)	($5,129)	($6,868)	($5,176)	($4,398)	($4,899)	($19,481)	($21,341)	($19,886)
Net income attributable to Brookline Bancorp, Inc.	7,654	9,429	9,490	8,813	11,863	11,401	7,529	6,349	35,386	37,142	27,600
Investment Securities Available-for-Sale | Reclassification out of Accumulated Other Comprehensive Income [Member]	'	'	'	'	'	'	'	'	'	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Gain on sales of securities	'	'	'	'	'	'	'	'	397	926	80
Provision for income taxes	'	'	'	'	'	'	'	'	-142	-328	-29
Net income attributable to Brookline Bancorp, Inc.	'	'	'	'	'	'	'	'	$255	$598	$51

Derivatives_and_Hedging_Activi3

Derivatives and Hedging Activities (Details 2) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'	'
Asset derivatives	$825	$1,317
Net amounts of assets presented in the statement of financial position	825	1,317
Gross amounts not offset in the statement of financial position	'	'
Net amount	825	1,317
Liability derivatives	856	1,380
Net amounts of liabilities presented in the statement of financial position	856	1,380
Gross amounts not offset in the statement of financial position	'	'
Cash collateral received	2,811	548
Net amount	$3,667	$1,928

Income_Taxes_Details

Income Taxes (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Current provision:	'	'	'	'	'	'	'	'	'	'	'
Federal	'	'	'	'	'	'	'	'	$12,799	$15,558	$14,115
State	'	'	'	'	'	'	'	'	4,238	5,120	4,987
Total current provision	'	'	'	'	'	'	'	'	17,037	20,678	19,102
Deferred provision (benefit):	'	'	'	'	'	'	'	'	'	'	'
Federal	'	'	'	'	'	'	'	'	2,572	389	811
State	'	'	'	'	'	'	'	'	-128	274	-27
Total deferred provision (benefit)	'	'	'	'	'	'	'	'	2,444	663	784
Total provision for income taxes	$4,325	$4,645	$5,382	$5,129	$6,868	$5,176	$4,398	$4,899	$19,481	$21,341	$19,886

Income_Taxes_Details_2

Income Taxes (Details 2) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Taxes [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Statutory U.S federal income tax rate (as a percent)	'	'	'	'	'	'	'	'	35.00%	35.00%	35.00%
Reconciliation of income tax expense	'	'	'	'	'	'	'	'	'	'	'
Expected income tax expense at statutory federal tax rate	'	'	'	'	'	'	'	'	$19,830,000	$20,899,000	$17,047,000
State taxes, net of federal income tax benefit	'	'	'	'	'	'	'	'	2,673,000	3,506,000	3,224,000
Bank-owned life insurance	'	'	'	'	'	'	'	'	-383,000	-409,000	0
Tax-exempt interest income	'	'	'	'	'	'	'	'	-310,000	-216,000	-157,000
Non-deductible other expenses	'	'	'	'	'	'	'	'	0	617,000	613,000
Income attributable to noncontrolling interest in subsidiary	'	'	'	'	'	'	'	'	-768,000	-560,000	-427,000
Tax credit - premises and equipment	'	'	'	'	'	'	'	'	-453,000	-1,593,000	0
Tax credits from investments in affordable housing projects	'	'	'	'	'	'	'	'	-1,058,000	-806,000	-464,000
Other, net	'	'	'	'	'	'	'	'	-50,000	-97,000	50,000
Total provision for income taxes	4,325,000	4,645,000	5,382,000	5,129,000	6,868,000	5,176,000	4,398,000	4,899,000	19,481,000	21,341,000	19,886,000
Effective income tax rate ( as a percent)	'	'	'	'	'	'	'	'	34.40%	35.70%	40.80%
Reduction in rehabilitation tax credits	'	'	'	'	'	'	'	'	'	-1,100,000	'
BankRI	'	'	'	'	'	'	'	'	'	'	'
Reconciliation of income tax expense	'	'	'	'	'	'	'	'	'	'	'
Decrease in deferred tax asset, state taxes	'	'	'	'	$500,000	'	'	'	'	$500,000	'

Income_Taxes_Details_3

Income Taxes (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Deferred tax assets:	'	'
Allowance for credit losses	$19,754,000	$16,667,000
Acquisition fair value adjustments	7,430,000	10,013,000
Unrealized loss on securities available for sale	5,119,000	0
Retirement and postretirement benefits	4,159,000	4,822,000
Deferred Compensation	1,989,000	2,254,000
Net operating loss and contribution carryovers	1,922,000	2,229,000
Non-accrual interest	878,000	948,000
Restricted stock and stock option plans	726,000	803,000
Write-downs of investment securities	442,000	795,000
Depreciation	0	235,000
Accrued expenses	375,000	200,000
Alternative minimum tax credits	31,000	31,000
Other	33,000	198,000
Total gross deferred tax assets	42,858,000	39,195,000
Deferred tax liabilities:	'	'
Identified intangible assets and goodwill	7,322,000	8,893,000
Depreciation	2,619,000	0
Unrealized gain on securities available for sale	0	2,015,000
Deferred loan origination costs, net	734,000	736,000
Investment in affordable housing projects	205,000	246,000
Unrecognized gain relating to postretirement obligation	268,000	92,000
Other	0	16,000
Total gross deferred tax liabilities	11,148,000	11,998,000
Net deferred tax asset	31,710,000	27,197,000
Net operating loss carryforwards for U.S. federal income tax purposes	5,500,000	'
Alternative minimum tax credit carryforwards for U.S. federal income tax purpose	31,000	'
Net operating loss carryforwards and credit subject to annual limitation	881,000	'
Reserve for loan losses	1,800,000	'
Percentage of the amount the used reserve for loan losses would be subject to taxation, if, the reserve is used for purposes other than to absorb the losses for which it was established	150.00%	'
Amount of liability that would result if 100% of the reserve were recaptured on which no provision has been made	$750,000	'
Reserve for loan losses recaptured (as a percent)	100.00%	'

Stockholders_Equity_Details

Stockholders' Equity (Details) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stockholders' Equity Note [Abstract]	'	'	'
Authorized serial preferred stock	50,000,000	'	'
Serial preferred stock, par value (in dollars per share)	$0.01	'	'
Preferred stock issued	0	'	'
Number of shares repurchased	0	0	0
Liquidation account, total	$20.60	$22.30	$24.40

Regulatory_Capital_Requirement2

Regulatory Capital Requirements (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Stockholders' equity reconciliation	'		'
Stockholders equity	$613,867		$612,097
Add: Minority interest	4,304		3,712
Add: Subordinated debenture	9,163		12,091
Less: disallowed goodwill and intangible assets	154,777		159,400
Less: Unrealized loss on available-for-sale equity securities	0		0
Less: Net unrealized (losses) gains on available-for-sale securities	-7,915		3,358
Tier 1 capital	480,472		465,142
Allowance for loan and lease losses not to exceed 1.25% of risk weighted assets	49,510		41,935
Unrealized gains on available-for-sale equity securities	0		0
Total	529,982	[1]	507,077	[1]
Percentage of adjusted total assets required for calculation of allowance for loan losses	1.25%		1.25%
Bank actual capital amount	'		'
Tier 1 leverage capital	480,472	[2]	465,142	[2]
Risk-based capital:	'		'
Tier 1	480,472	[3]	465,142	[3]
Total	529,982	[1]	507,077	[1]
Bank actual capital ratio	'		'
Tier 1 leverage capital ratio (as a percent)	9.40%	[2]	9.40%	[2]
Risk-based capital:	'		'
Tier 1 (as a percent)	11.00%	[3]	10.90%	[3]
Total (as a percent)	12.20%	[1]	11.80%	[1]
Minimum capital adequacy amount	'		'
Tier 1 leverage capital	205,946	[2]	197,094	[2]
Risk-based capital:	'		'
Tier 1	174,512	[3]	171,481	[3]
Total	349,159	[1]	342,909	[1]
Minimum capital adequacy ratio	'		'
Tier 1 leverage capital ratio (as a percent)	4.00%	[2]	4.00%	[2]
Risk-based capital:	'		'
Tier 1 (as a percent)	4.00%	[3]	4.00%	[3]
Total (as a percent)	8.00%	[1]	8.00%	[1]
Classified as well capitalized ratio	'		'
Tier 1 leverage capital ratio (as a percent)	5.00%	[2]	'
Risk-based capital:	'		'
Tier 1 (as a percent)	6.00%	[3]	'
Total (as a percent)	10.00%	[1]	'
Brookline Bank	'		'
Stockholders' equity reconciliation	'		'
Stockholders equity	301,291		288,859
Add: Minority interest	4,304		3,712
Add: Subordinated debenture	0		0
Less: disallowed goodwill and intangible assets	7,647		7,991
Less: Unrealized loss on available-for-sale equity securities	0		0
Less: Net unrealized (losses) gains on available-for-sale securities	-1,874		1,874
Tier 1 capital	299,822		282,706
Allowance for loan and lease losses not to exceed 1.25% of risk weighted assets	35,905		35,923
Unrealized gains on available-for-sale equity securities	0		0
Total	335,727	[1]	318,629	[1]
Bank actual capital amount	'		'
Tier 1 leverage capital	299,822	[2]	282,706	[2]
Risk-based capital:	'		'
Tier 1	299,822	[3]	282,706	[3]
Total	335,727	[1]	318,629	[1]
Bank actual capital ratio	'		'
Tier 1 leverage capital ratio (as a percent)	9.40%	[2]	9.30%	[2]
Risk-based capital:	'		'
Tier 1 (as a percent)	10.40%	[3]	9.80%	[3]
Total (as a percent)	11.70%	[1]	11.00%	[1]
Minimum capital adequacy amount	'		'
Tier 1 leverage capital	127,992	[2]	121,725	[2]
Risk-based capital:	'		'
Tier 1	114,874	[3]	115,626	[3]
Total	229,753	[1]	231,310	[1]
Minimum capital adequacy ratio	'		'
Tier 1 leverage capital ratio (as a percent)	4.00%	[2]	4.00%	[2]
Risk-based capital:	'		'
Tier 1 (as a percent)	4.00%	[3]	4.00%	[3]
Total (as a percent)	8.00%	[1]	8.00%	[1]
Classified as well capitalized	'		'
Tier 1 leverage capital	159,990	[2]	152,156	[2]
Risk-based capital:	'		'
Tier 1	172,311	[3]	173,439	[3]
Total	287,192	[1]	289,137	[1]
Classified as well capitalized ratio	'		'
Tier 1 leverage capital ratio (as a percent)	5.00%	[2]	5.00%	[2]
Risk-based capital:	'		'
Tier 1 (as a percent)	6.00%	[3]	6.00%	[3]
Total (as a percent)	10.00%	[1]	10.00%	[1]
BankRI	'		'
Stockholders' equity reconciliation	'		'
Stockholders equity	236,579		247,606
Add: Minority interest	0		0
Add: Subordinated debenture	0		0
Less: disallowed goodwill and intangible assets	106,593		110,203
Less: Unrealized loss on available-for-sale equity securities	0		0
Less: Net unrealized (losses) gains on available-for-sale securities	-4,918		1,303
Tier 1 capital	134,904		136,100
Allowance for loan and lease losses not to exceed 1.25% of risk weighted assets	10,936		5,053
Unrealized gains on available-for-sale equity securities	7		18
Total	145,847	[1]	141,171	[1]
Bank actual capital amount	'		'
Tier 1 leverage capital	134,904	[2]	136,100	[2]
Risk-based capital:	'		'
Tier 1	134,904	[3]	136,100	[3]
Total	145,847	[1]	141,171	[1]
Bank actual capital ratio	'		'
Tier 1 leverage capital ratio (as a percent)	8.10%	[2]	8.50%	[2]
Risk-based capital:	'		'
Tier 1 (as a percent)	10.60%	[3]	11.50%	[3]
Total (as a percent)	11.40%	[1]	12.00%	[1]
Minimum capital adequacy amount	'		'
Tier 1 leverage capital	66,784	[2]	64,047	[2]
Risk-based capital:	'		'
Tier 1	52,904	[3]	47,175	[3]
Total	105,782	[1]	94,350	[1]
Minimum capital adequacy ratio	'		'
Tier 1 leverage capital ratio (as a percent)	4.00%	[2]	4.00%	[2]
Risk-based capital:	'		'
Tier 1 (as a percent)	4.00%	[3]	4.00%	[3]
Total (as a percent)	8.00%	[1]	8.00%	[1]
Classified as well capitalized	'		'
Tier 1 leverage capital	83,480	[2]	80,059	[2]
Risk-based capital:	'		'
Tier 1	79,355	[3]	70,763	[3]
Total	132,228	[1]	117,937	[1]
Classified as well capitalized ratio	'		'
Tier 1 leverage capital ratio (as a percent)	5.00%	[2]	5.00%	[2]
Risk-based capital:	'		'
Tier 1 (as a percent)	6.00%	[3]	6.00%	[3]
Total (as a percent)	10.00%	[1]	10.00%	[1]
First Ipswich Bancorp:	'		'
Stockholders' equity reconciliation	'		'
Stockholders equity	34,641		35,515
Add: Minority interest	0		0
Add: Subordinated debenture	0		0
Less: disallowed goodwill and intangible assets	5,271		5,940
Less: Unrealized loss on available-for-sale equity securities	10		0
Less: Net unrealized (losses) gains on available-for-sale securities	-1,075		366
Tier 1 capital	30,435		29,209
Allowance for loan and lease losses not to exceed 1.25% of risk weighted assets	1,854		959
Unrealized gains on available-for-sale equity securities	0		0
Total	32,289	[1]	30,168	[1]
Bank actual capital amount	'		'
Tier 1 leverage capital	30,435	[2]	29,209	[2]
Risk-based capital:	'		'
Tier 1	30,435	[3]	29,209	[3]
Total	32,289	[1]	30,168	[1]
Bank actual capital ratio	'		'
Tier 1 leverage capital ratio (as a percent)	9.80%	[2]	9.70%	[2]
Risk-based capital:	'		'
Tier 1 (as a percent)	13.60%	[3]	13.20%	[3]
Total (as a percent)	14.40%	[1]	13.70%	[1]
Minimum capital adequacy amount	'		'
Tier 1 leverage capital	12,461	[2]	12,020	[2]
Risk-based capital:	'		'
Tier 1	8,971	[3]	8,824	[3]
Total	17,938	[1]	17,642	[1]
Minimum capital adequacy ratio	'		'
Tier 1 leverage capital ratio (as a percent)	4.00%	[2]	4.00%	[2]
Risk-based capital:	'		'
Tier 1 (as a percent)	4.00%	[3]	4.00%	[3]
Total (as a percent)	8.00%	[1]	8.00%	[1]
Classified as well capitalized	'		'
Tier 1 leverage capital	15,576	[2]	15,025	[2]
Risk-based capital:	'		'
Tier 1	13,457	[3]	13,237	[3]
Total	$22,423	[1]	$22,053	[1]
Classified as well capitalized ratio	'		'
Tier 1 leverage capital ratio (as a percent)	5.00%	[2]	5.00%	[2]
Risk-based capital:	'		'
Tier 1 (as a percent)	6.00%	[3]	6.00%	[3]
Total (as a percent)	10.00%	[1]	10.00%	[1]
[1]	Total risk-based capital ratio is calculated by dividing total capital by risk-weighted assets.
[2]	TierB 1 leverage capital ratio is calculated by dividing TierB 1 capital by average assets.
[3]	TierB 1 risk-based capital ratio is calculated by dividing TierB 1 capital by risk-weighted assets.

Employee_Benefit_Plans_Details

Employee Benefit Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
	Y
	plan
	H
Change in postretirement benefit obligation recognized in other comprehensive income:	'	'	'
Total pre-tax changes in postretirement benefit obligation recognized in other comprehensive income:	($468,000)	$10,000	$57,000
401(k) Plans	'	'	'
Number of 401(k) plans administered	2	'	'
Minimum employee age required to participate in the plan (in years)	21	'	'
Minimum number of working hours in a plan year required to participate in the plan	1,000	'	'
Vesting period of participants in employer contribution (in years)	'3 years	'	'
Expense for the company plan contributions	2,000,000	1,800,000	1,000,000
401(k) plan 1	'	'	'
401(k) Plans	'	'	'
Company contribution as percentage of compensation of eligible employees	5.00%	'	'
401(k) plan 2	'	'	'
401(k) Plans	'	'	'
Company contribution as percentage of compensation of eligible employees	4.00%	'	'
Health Insurance Postretirement Benefit	'	'	'
Net periodic benefit expenses:	'	'	'
Service cost	61,000	74,000	74,000
Interest cost	47,000	55,000	61,000
Prior service credit	-21,000	-21,000	-21,000
Actuarial gain	-16,000	-3,000	-4,000
Net periodic benefit expense	71,000	105,000	110,000
Change in postretirement benefit obligation recognized in other comprehensive income:	'	'	'
Net actuarial loss (gain)	489,000	11,000	-36,000
Prior service credit	-21,000	-21,000	-21,000
Total pre-tax changes in postretirement benefit obligation recognized in other comprehensive income:	468,000	-10,000	-57,000
Discount rate used to determine the actuarial present value of projected postretirement benefit obligations (as a percent)	4.90%	3.95%	5.25%
Estimated prior service credit that will be amortized from accumulated other comprehensive income into net periodic benefit cost	21,000	'	'
Liability for the postretirement benefits included in accrued expenses and other liabilities	1,100,000	1,500,000	'
Assumed health care trend rates used in 2014 through 2018, high end of range (as a percent)	7.30%	'	'
Assumed health care trend rates used in 2014 through 2018, low end of range (as a percent)	6.50%	'	'
Assumed health care trend rate after 2018 (as a percent)	5.30%	'	'
Effect of 1% change in assumed health care cost trend rates	'	'	'
Effect of 1% increase on total service and interest cost components of net periodic postretirement benefit costs	26,000	'	'
Effect of 1% decrease on total service and interest cost components of net periodic postretirement benefit costs	-20,000	'	'
Effect of 1% increase on the accumulated postretirement benefit obligation	215,000	'	'
Effect of 1% decrease on the accumulated postretirement benefit obligation	-171,000	'	'
Health Insurance Postretirement Benefit | Below age 65	'	'	'
Change in postretirement benefit obligation recognized in other comprehensive income:	'	'	'
Actual health care trend that will be used to measure the accumulated postretirement benefit obligation (as a percent)	2.70%	'	'
Actual health care trend used to measure the accumulated postretirement benefit obligation (as a percent)	'	3.00%	'
Health Insurance Postretirement Benefit | Over age 65	'	'	'
Change in postretirement benefit obligation recognized in other comprehensive income:	'	'	'
Actual health care trend that will be used to measure the accumulated postretirement benefit obligation (as a percent)	-14.50%	'	'
Actual health care trend used to measure the accumulated postretirement benefit obligation (as a percent)	'	-14.70%	'
Nonqualified Plan	'	'	'
401(k) Plans	'	'	'
Expenses associated with deferred compensation plan	500,000	500,000	0
Accrued liabilities with deferred compensation plan	$400,000	$500,000	$0

Employee_Benefit_Plans_Details1

Employee Benefit Plans (Details 2) (Supplemental retirement plan, USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
	participant
Supplemental retirement plan	'	'
Supplemental Executive Retirement Agreements	'	'
Number of participants	13	'
Expenses for benefits payable recognized under agreement	$600,000	$400,000
Aggregate benefits payable included in accrued expenses and other liabilities	$10,100,000	$10,700,000
Discount rate used to determine the actuarial present value (as a percent)	5.00%	4.30%

Employee_Benefit_Plans_Details2

Employee Benefit Plans (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-Based Payment Arrangements	'	'	'
Unallocated shares	291,666	333,918	'
Unallocated shares, aggregate cost	$1,590,000	$1,820,000	'
Compensation and employee benefits expense	230,000	242,000	418,000
Employee Stock Ownership Plan	'	'	'
Share-Based Payment Arrangements	'	'	'
ESOP loan to purchase shares of entity's common stock	546,986	'	'
Number of years during which quarterly installments are payable	'30 years	'	'
Percentage of interest payable per annum on loan obtained by the ESOP	8.50%	'	'
Outstanding balance of loan	2,300,000	2,600,000	'
Employees vesting rate in ESOP account (as a percent)	20.00%	'	'
Credited service period (in years)	'3 years	'	'
Unallocated shares	291,666	333,918	'
Unallocated shares, aggregate cost	1,500,000	1,700,000	'
Unallocated shares, market value	2,800,000	2,800,000	'
Compensation and employee benefits expense	$400,000	$400,000	$400,000
Number of shares committed to be released to eligible employees	42,252	44,292	46,207

Employee_Benefit_Plans_Details3

Employee Benefit Plans (Details 4) (USD $)

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Apr. 20, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Restricted stock under 2003 RRP plan

2011 Restricted Stock Award Plan

2011 Restricted Stock Award Plan

2011 Restricted Stock Award Plan

Recognition and Retention Plans

Recognition and Retention Plans

Recognition and Retention Plans

2003 Stock Option Plan

2003 Stock Option Plan

2003 RRP

1999 RRP

Stock Options [Member]

Stock Options [Member]

Stock Options [Member]

institution

Share-based payment arrangements

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Maximum number of shares awarded

'

'

'

'

500,000

'

'

'

'

'

1,250,000

546,986

'

'

'

Stock granted (in shares)

'

'

138,500

166,941

'

'

'

'

'

'

'

'

'

'

'

Percentage of granted award which will vest

'

'

50.00%

'

'

'

'

'

'

'

'

'

'

'

'

Period over which award vested (in years)

'

'

'3 years

'

'

'

'

'

'

'

'

'

'

'

'

Portion of the time vesting shares vesting at first anniversary (as a percent)

'

'

33.33%

'

'

'

'

'

'

'

'

'

'

'

'

Portion of the time vesting shares vesting at second anniversary (as a percent)

'

'

33.33%

'

'

'

'

'

'

'

'

'

'

'

'

Portion of the time vesting shares vesting at third anniversary (as a percent)

'

'

33.33%

'

'

'

'

'

'

'

'

'

'

'

'

Remaining percentage of granted award which will vest

'

'

50.00%

'

'

'

'

'

'

'

'

'

'

'

'

Number of financial institutions in defined peer group

'

'

22

'

'

'

'

'

'

'

'

'

'

'

'

Shares available for award

'

11,599

'

'

'

'

'

'

2,265,155

'

'

'

'

'

'

Total expense for shares awarded

'

'

'

'

'

$1,200,000

$800,000

$400,000

'

'

'

'

'

$10,000

$47,000

Compensation cost of non-vested shares

'

'

'

'

'

1,500,000

'

'

'

'

'

'

'

'

'

Dividends paid on unvested shares recognized as compensation expense

'

'

'

'

'

30,000

11,000

12,000

'

'

'

'

'

'

'

Exercisable period upon happening of a specific event, low end of range (in months)

'

'

'

'

'

'

'

'

'

'

'

'

'3 months

'

'

Exercisable period upon happening of a specific event, high end of range (in years)

'

'

'

'

'

'

'

'

'

'

'

'

'5 years

'

'

Options granted or awarded (in shares)

'

'

'

'

'

'

'

'

'

5,000

'

'

'

'

'

Stock option activity

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Outstanding at the beginning of the period (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

1,075,845

1,090,845

1,128,345

Granted (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

0

0

5,000

Exercised (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

0

0

0

Forfeited/Canceled (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

-841,000

-15,000

-42,500

Outstanding at the end of the period (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

234,845

1,075,845

1,090,845

Exercisable at the end of the period (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

234,845

'

'

Stock Option Activity, Weighted Average Exercise Price

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Outstanding at the beginning of the period (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

$14.95

$14.08

$14.08

Granted (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

$0

$0

$8.29

Exercised (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

$0

$0

$0

Forfeited/Canceled (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

$14.95

$14.95

$14.67

Outstanding at the end of the period (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

$10.43

$14.95

$14.08

Exercisable at the end of the period (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

$10.43

'

'

Stock Option Activity, Aggregate Intrinsic Value

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Outstanding at the end of the period

'

'

'

'

'

'

'

'

'

'

'

'

0

'

'

Exercisable at the end of the period

'

'

'

'

'

'

'

'

'

'

'

'

$0

'

'

Stock Option Activity, Weighted Average Contractual Term

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Outstanding at the end of the period (in years)

'

'

'

'

'

'

'

'

'

'

'

'

'5 years 8 months 12 days

'

'

Exercisable at the end of the period (in years)

'

'

'

'

'

'

'

'

'

'

'

'

'5 years 8 months 12 days

'

'

Valuation assumptions used to determine fair value of stock option award

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Dividend yield (as a percent)

4.30%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Expected volatility (as a percent)

34.38%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Risk-Free interest rate (as a percent)

1.85%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Expected life of options (in years)

'7 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Fair_Value_of_Financial_Instru2

Fair Value of Financial Instruments (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Fair value of assets	'	'
Estimated Fair Value	$492,428	$481,323
Interest-rate swaps, asset	825	1,317
Interest-rate swaps, liability	856	1,380
GSEs	'	'
Fair value of assets	'	'
Estimated Fair Value	12,180	69,809
Municipal obligations	'	'
Fair value of assets	'	'
Estimated Fair Value	1,086	1,101
Auction-rate municipal obligations	'	'
Fair value of assets	'	'
Estimated Fair Value	1,775	1,976
Corporate debt obligations	'	'
Fair value of assets	'	'
Estimated Fair Value	28,200	10,700
Pooled Trust Preferred Securities	'	'
Fair value of assets	'	'
Estimated Fair Value	1,200	2,500
Private-label CMO	'	'
Fair value of assets	'	'
Estimated Fair Value	3,400	6,900
SBA commercial loan asset-backed securities	'	'
Fair value of assets	'	'
Estimated Fair Value	243	381
Marketable equity securities	'	'
Fair value of assets	'	'
Estimated Fair Value	1,300	'
Recurring basis | Level 1	'	'
Fair value of assets	'	'
Interest-rate swaps, asset	0	0
Interest-rate swaps, liability	0	0
Recurring basis | Level 1 | Investment securities available for sale	'	'
Fair value of assets	'	'
Estimated Fair Value	1,310	1,337
Recurring basis | Level 1 | GSEs	'	'
Fair value of assets	'	'
Estimated Fair Value	0	0
Recurring basis | Level 1 | Municipal obligations	'	'
Fair value of assets	'	'
Estimated Fair Value	0	0
Recurring basis | Level 1 | Auction-rate municipal obligations	'	'
Fair value of assets	'	'
Estimated Fair Value	0	0
Recurring basis | Level 1 | Corporate debt obligations	'	'
Fair value of assets	'	'
Estimated Fair Value	0	0
Recurring basis | Level 1 | Pooled Trust Preferred Securities	'	'
Fair value of assets	'	'
Estimated Fair Value	0	0
Recurring basis | Level 1 | GSE CMOs	'	'
Fair value of assets	'	'
Estimated Fair Value	0	0
Recurring basis | Level 1 | GSE MBSs	'	'
Fair value of assets	'	'
Estimated Fair Value	0	0
Recurring basis | Level 1 | Private-label CMO	'	'
Fair value of assets	'	'
Estimated Fair Value	0	0
Recurring basis | Level 1 | SBA commercial loan asset-backed securities	'	'
Fair value of assets	'	'
Estimated Fair Value	0	0
Recurring basis | Level 1 | Marketable equity securities	'	'
Fair value of assets	'	'
Estimated Fair Value	1,310	1,337
Recurring basis | Level 2	'	'
Fair value of assets	'	'
Interest-rate swaps, asset	825	1,317
Interest-rate swaps, liability	856	1,380
Recurring basis | Level 2 | Investment securities available for sale	'	'
Fair value of assets	'	'
Estimated Fair Value	489,343	477,069
Recurring basis | Level 2 | GSEs	'	'
Fair value of assets	'	'
Estimated Fair Value	12,180	69,809
Recurring basis | Level 2 | Municipal obligations	'	'
Fair value of assets	'	'
Estimated Fair Value	1,086	1,101
Recurring basis | Level 2 | Auction-rate municipal obligations	'	'
Fair value of assets	'	'
Estimated Fair Value	0	0
Recurring basis | Level 2 | Corporate debt obligations	'	'
Fair value of assets	'	'
Estimated Fair Value	28,224	10,685
Recurring basis | Level 2 | Pooled Trust Preferred Securities	'	'
Fair value of assets	'	'
Estimated Fair Value	1,210	1,578
Recurring basis | Level 2 | GSE CMOs	'	'
Fair value of assets	'	'
Estimated Fair Value	243,644	217,001
Recurring basis | Level 2 | GSE MBSs	'	'
Fair value of assets	'	'
Estimated Fair Value	199,401	169,648
Recurring basis | Level 2 | Private-label CMO	'	'
Fair value of assets	'	'
Estimated Fair Value	3,355	6,866
Recurring basis | Level 2 | SBA commercial loan asset-backed securities	'	'
Fair value of assets	'	'
Estimated Fair Value	243	381
Recurring basis | Level 2 | Marketable equity securities	'	'
Fair value of assets	'	'
Estimated Fair Value	0	0
Recurring basis | Level 3	'	'
Fair value of assets	'	'
Interest-rate swaps, asset	0	0
Interest-rate swaps, liability	0	0
Recurring basis | Level 3 | Investment securities available for sale	'	'
Fair value of assets	'	'
Estimated Fair Value	1,775	2,917
Recurring basis | Level 3 | GSEs	'	'
Fair value of assets	'	'
Estimated Fair Value	0	0
Recurring basis | Level 3 | Municipal obligations	'	'
Fair value of assets	'	'
Estimated Fair Value	0	0
Recurring basis | Level 3 | Auction-rate municipal obligations	'	'
Fair value of assets	'	'
Estimated Fair Value	1,775	1,976
Recurring basis | Level 3 | Corporate debt obligations	'	'
Fair value of assets	'	'
Estimated Fair Value	0	0
Recurring basis | Level 3 | Pooled Trust Preferred Securities	'	'
Fair value of assets	'	'
Estimated Fair Value	0	941
Recurring basis | Level 3 | GSE CMOs	'	'
Fair value of assets	'	'
Estimated Fair Value	0	0
Recurring basis | Level 3 | GSE MBSs	'	'
Fair value of assets	'	'
Estimated Fair Value	0	0
Recurring basis | Level 3 | Private-label CMO	'	'
Fair value of assets	'	'
Estimated Fair Value	0	0
Recurring basis | Level 3 | SBA commercial loan asset-backed securities	'	'
Fair value of assets	'	'
Estimated Fair Value	0	0
Recurring basis | Level 3 | Marketable equity securities	'	'
Fair value of assets	'	'
Estimated Fair Value	0	0
Recurring basis | Estimated Fair Value	'	'
Fair value of assets	'	'
Interest-rate swaps, asset	825	1,317
Interest-rate swaps, liability	856	1,380
Recurring basis | Estimated Fair Value | Investment securities available for sale	'	'
Fair value of assets	'	'
Estimated Fair Value	492,428	481,323
Recurring basis | Estimated Fair Value | GSEs	'	'
Fair value of assets	'	'
Estimated Fair Value	12,180	69,809
Recurring basis | Estimated Fair Value | Municipal obligations	'	'
Fair value of assets	'	'
Estimated Fair Value	1,086	1,101
Recurring basis | Estimated Fair Value | Auction-rate municipal obligations	'	'
Fair value of assets	'	'
Estimated Fair Value	1,775	1,976
Recurring basis | Estimated Fair Value | Corporate debt obligations	'	'
Fair value of assets	'	'
Estimated Fair Value	28,224	10,685
Recurring basis | Estimated Fair Value | Pooled Trust Preferred Securities	'	'
Fair value of assets	'	'
Estimated Fair Value	1,210	2,519
Recurring basis | Estimated Fair Value | GSE CMOs	'	'
Fair value of assets	'	'
Estimated Fair Value	243,644	217,001
Recurring basis | Estimated Fair Value | GSE MBSs	'	'
Fair value of assets	'	'
Estimated Fair Value	199,401	169,648
Recurring basis | Estimated Fair Value | Private-label CMO	'	'
Fair value of assets	'	'
Estimated Fair Value	3,355	6,866
Recurring basis | Estimated Fair Value | SBA commercial loan asset-backed securities	'	'
Fair value of assets	'	'
Estimated Fair Value	243	381
Recurring basis | Estimated Fair Value | Marketable equity securities	'	'
Fair value of assets	'	'
Estimated Fair Value	$1,310	$1,337

Fair_Value_of_Financial_Instru3

Fair Value of Financial Instruments (Details 2) (Nonrecurring basis, USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Level 1	'	'
Fair value of assets	'	'
Total assets reported at fair value	$0	$0
Level 2	'	'
Fair value of assets	'	'
Total assets reported at fair value	1,001	38,240
Level 3	'	'
Fair value of assets	'	'
Total assets reported at fair value	12,676	0
Estimated Fair Value	'	'
Fair value of assets	'	'
Total assets reported at fair value	13,677	38,240
Collateral-dependent impaired loans and leases [Member] | Level 1	'	'
Fair value of assets	'	'
Total assets reported at fair value	0	0
Collateral-dependent impaired loans and leases [Member] | Level 2	'	'
Fair value of assets	'	'
Total assets reported at fair value	0	36,749
Collateral-dependent impaired loans and leases [Member] | Level 3	'	'
Fair value of assets	'	'
Total assets reported at fair value	12,099	0
Collateral-dependent impaired loans and leases [Member] | Estimated Fair Value	'	'
Fair value of assets	'	'
Total assets reported at fair value	12,099	36,749
Other real estate owned | Level 1	'	'
Fair value of assets	'	'
Total assets reported at fair value	0	0
Other real estate owned | Level 2	'	'
Fair value of assets	'	'
Total assets reported at fair value	0	903
Other real estate owned | Level 3	'	'
Fair value of assets	'	'
Total assets reported at fair value	577	0
Other real estate owned | Estimated Fair Value	'	'
Fair value of assets	'	'
Total assets reported at fair value	577	903
Repossessed assets | Level 1	'	'
Fair value of assets	'	'
Total assets reported at fair value	0	0
Repossessed assets | Level 2	'	'
Fair value of assets	'	'
Total assets reported at fair value	1,001	588
Repossessed assets | Level 3	'	'
Fair value of assets	'	'
Total assets reported at fair value	0	0
Repossessed assets | Estimated Fair Value	'	'
Fair value of assets	'	'
Total assets reported at fair value	$1,001	$588

Fair_Value_of_Financial_Instru4

Fair Value of Financial Instruments (Details 3) (Level 3, Recurring basis, USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013
Auction-rate municipal obligations | Discounted cash flow [Member]	'
Quantitative information for Level 3 Fair Value Measurements Assets	'
Fair value Assets	1,775
Auction-rate municipal obligations | Discounted cash flow [Member] | Minimum	'
Quantitative information for Level 3 Fair Value Measurements Assets	'
Discount rates (as a percent)	0.00%
Auction-rate municipal obligations | Discounted cash flow [Member] | Maximum	'
Quantitative information for Level 3 Fair Value Measurements Assets	'
Discount rates (as a percent)	5.00%
Auction-rate municipal obligations | Discounted cash flow [Member] | Weighted Average	'
Quantitative information for Level 3 Fair Value Measurements Assets	'
Discount rates (as a percent)	4.00%
Collateral-dependent impaired loans and leases [Member] | Appraisal of collateral [Member]	'
Quantitative information for Level 3 Fair Value Measurements Assets	'
Fair value Assets	12,099	[1]
Other real estate owned [Member] | Appraisal of collateral [Member]	'
Quantitative information for Level 3 Fair Value Measurements Assets	'
Fair value Assets	577	[1]
[1]	For impaired loans deemed collateral dependent, where impairment is measured using the fair value of the collateral, the Bank will either obtain a new appraisal or use another available source of collateral assessment to determine a reasonable estimate of the fair value of the collateral.

Fair_Value_of_Financial_Instru5

Fair Value of Financial Instruments (Details 4) (Investment securities available for sale, USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Investment securities available for sale	'	'
Reconciliation of assets measured at fair value on a recurring basis	'	'
Investment securities available for sale, beginning of period	$2,917	$3,208
Acquired, BankRI	0	184
Principal paydowns and other	-1,150	-836
Total unrealized gains included in other comprehensive income	8	361
Investment securities available for sale, end of period	$1,775	$2,917

Fair_Value_of_Financial_Instru6

Fair Value of Financial Instruments (Details 5) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Financial assets:	'	'
Investment securities held-to-maturity	$500	$502
Loans and leases, net	4,313,992	4,134,560
Financial liabilities:	'	'
Certificate of deposit	934,668	1,010,941
Borrowed funds	43,782	63,104
Investment securities held-to-maturity (fair value of $500 and $502, respectively)	500	500
Level 1	'	'
Financial assets:	'	'
Investment securities held-to-maturity	0	0
Loans held for sale	0	0
Loans and leases, net	0	0
Financial liabilities:	'	'
Certificate of deposit	0	0
Borrowed funds	0	0
Level 2	'	'
Financial assets:	'	'
Investment securities held-to-maturity	0	0
Loans held for sale	13,372	3,233
Loans and leases, net	0	0
Financial liabilities:	'	'
Certificate of deposit	938,703	1,019,916
Borrowed funds	815,910	872,046
Level 3	'	'
Financial assets:	'	'
Investment securities held-to-maturity	500	502
Loans held for sale	0	0
Loans and leases, net	4,552,556	4,193,678
Financial liabilities:	'	'
Certificate of deposit	0	0
Borrowed funds	0	0
Carrying Value	'	'
Financial assets:	'	'
Investment securities held-to-maturity	500	500
Loans held for sale	13,372	3,233
Loans and leases, net	4,313,992	4,134,560
Financial liabilities:	'	'
Certificate of deposit	934,668	1,010,941
Borrowed funds	812,555	853,969
Estimated Fair Value	'	'
Financial assets:	'	'
Investment securities held-to-maturity	500	502
Loans held for sale	13,372	3,233
Loans and leases, net	4,552,556	4,193,678
Financial liabilities:	'	'
Certificate of deposit	938,703	1,019,916
Borrowed funds	$815,910	$872,046

Condensed_Parent_Company_Finan2

Condensed Parent Company Financial Statements (Details) (USD $)

3 Months Ended

12 Months Ended

In Thousands, except Share data, unless otherwise specified

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

ASSETS

'

'

'

'

'

'

'

'

'

'

'

'

Cash and due from banks

$37,148

'

'

'

$78,441

'

'

'

$37,148

$78,441

'

'

Short-term investments

55,357

'

'

'

38,656

'

'

'

55,357

38,656

'

'

Total cash and cash equivalents

92,505

'

'

'

117,097

'

'

'

92,505

117,097

106,296

'

Restricted equity securities

66,559

'

'

'

68,661

'

'

'

66,559

68,661

'

'

Premises and equipment, net

80,505

'

'

'

70,791

'

'

'

80,505

70,791

'

'

Deferred tax asset

31,710

'

'

'

27,197

'

'

'

31,710

27,197

'

'

Goodwill

137,890

'

'

'

137,890

'

'

'

137,890

137,890

45,799

43,241

Other assets

77,180

'

'

'

83,281

'

'

'

77,180

83,281

'

'

Total assets

5,325,106

'

'

'

5,147,534

'

'

'

5,325,106

5,147,534

'

'

Liabilities and Stockholders' Equity

'

'

'

'

'

'

'

'

'

'

'

'

Demand checking accounts

707,023

'

'

'

623,274

'

'

'

707,023

623,274

'

'

Borrowed funds

812,555

'

'

'

853,969

'

'

'

812,555

853,969

'

'

Deferred tax liability

11,148

'

'

'

11,998

'

'

'

11,148

11,998

'

'

Accrued expenses and other liabilities

51,485

'

'

'

54,551

'

'

'

51,485

54,551

'

'

Total liabilities

4,706,935

'

'

'

4,531,725

'

'

'

4,706,935

4,531,725

'

'

Stockholders' equity

'

'

'

'

'

'

'

'

'

'

'

'

Common stock

757

'

'

'

757

'

'

'

757

757

'

'

Additional paid-in capital

617,538

'

'

'

618,426

'

'

'

617,538

618,426

'

'

Retained earnings, partially restricted

64,903

'

'

'

53,358

'

'

'

64,903

53,358

'

'

Accumulated other comprehensive (loss) income

-7,915

'

'

'

3,483

'

'

'

-7,915

3,483

1,963

2,348

Treasury stock, at cost; 5,171,985 and 5,373,733 shares, respectively

-59,826

'

'

'

-62,107

'

'

'

-59,826

-62,107

'

'

Treasury stock, shares

5,171,985

'

'

'

5,373,733

'

'

'

5,171,985

5,373,733

'

'

Unallocated common stock held by ESOP; 291,666 shares and 333,918 shares, respectively

-1,590

'

'

'

-1,820

'

'

'

-1,590

-1,820

'

'

Unallocated common stock held by ESOP, shares

291,666

'

'

'

333,918

'

'

'

291,666

333,918

'

'

Total Brookline Bancorp, Inc. Stockholders' equity

613,867

'

'

'

612,097

'

'

'

613,867

612,097

'

'

Total liabilities and stockholders' equity

5,325,106

'

'

'

5,147,534

'

'

'

5,325,106

5,147,534

'

'

Interest and dividend income:

'

'

'

'

'

'

'

'

'

'

'

'

Short-term investments

'

'

'

'

'

'

'

'

111

208

105

'

Total interest and dividend income

51,049

50,823

52,900

51,612

52,976

55,394

51,839

52,991

206,384

213,200

140,535

'

Interest expense:

'

'

'

'

'

'

'

'

'

'

'

'

Net interest income

43,774

43,412

45,363

43,669

44,564

46,411

42,759

43,634

176,218

177,368

110,199

'

Non-interest expense:

'

'

'

'

'

'

'

'

'

'

'

'

Compensation and employee benefits

'

'

'

'

'

'

'

'

65,261

58,830

30,789

'

Occupancy

'

'

'

'

'

'

'

'

12,616

10,611

6,138

'

Equipment and data processing

'

'

'

'

'

'

'

'

16,899

14,540

9,144

'

Professional services

'

'

'

'

'

'

'

'

5,695

12,475

5,375

'

Advertising and marketing

'

'

'

'

'

'

'

'

3,003

2,984

1,376

'

Other

30,193

28,399

29,638

29,607

27,072

29,165

27,350

31,166

11,261

11,101

6,787

'

Total non-interest expense

'

'

'

'

'

'

'

'

122,460

120,375

62,925

'

(Credit) provision for income taxes

4,325

4,645

5,382

5,129

6,868

5,176

4,398

4,899

19,481

21,341

19,886

'

Net income attributable to Brookline Bancorp, Inc.

7,654

9,429

9,490

8,813

11,863

11,401

7,529

6,349

35,386

37,142

27,600

'

Cash flows from operating activities:

'

'

'

'

'

'

'

'

'

'

'

'

Net income attributable to Brookline Bancorp, Inc.

7,654

9,429

9,490

8,813

11,863

11,401

7,529

6,349

35,386

37,142

27,600

'

Adjustments to reconcile net income to net cash provided from operating activities:

'

'

'

'

'

'

'

'

'

'

'

'

Net cash provided from operating activities

'

'

'

'

'

'

'

'

86,060

59,311

46,233

'

Cash flows from investing activities:

'

'

'

'

'

'

'

'

'

'

'

'

Acquisitions, net of cash and cash equivalents acquired

'

'

'

'

'

'

'

'

0

-89,258

5,792

'

Purchase of restricted equity securities

'

'

'

'

'

'

'

'

-5

-15,505

0

'

Purchase of premises and equipment

'

'

'

'

'

'

'

'

-16,443

-23,664

-19,910

'

Net cash used in investing activities

'

'

'

'

'

'

'

'

-266,848

-296,821

-300,358

'

Cash flows from financing activities:

'

'

'

'

'

'

'

'

'

'

'

'

Increase in demand checking, NOW, savings and money market accounts

'

'

'

'

'

'

'

'

295,020

312,644

273,693

'

Payment of dividends on common stock

'

'

'

'

'

'

'

'

-23,841

-23,777

-19,964

'

Net cash provided from financing activities

'

'

'

'

'

'

'

'

156,196

248,311

294,513

'

Cash and cash equivalents at beginning of year

'

'

'

117,097

'

'

'

106,296

117,097

106,296

65,908

'

Cash and cash equivalents at end of year

92,505

'

'

'

117,097

'

'

'

92,505

117,097

106,296

'

Cash paid during the year for:

'

'

'

'

'

'

'

'

'

'

'

'

Interest on subordinated debt

'

'

'

'

'

'

'

'

34,303

40,682

32,029

'

Income taxes

'

'

'

'

'

'

'

'

19,137

20,570

20,607

'

Bancorp Rhode Island, Inc.:

'

'

'

'

'

'

'

'

'

'

'

'

Acquisition

'

'

'

'

'

'

'

'

'

'

'

'

Fair value of assets acquired, net of cash and cash equivalents acquired

'

'

'

'

'

'

'

'

0

1,571,817

0

'

Fair value of liabilities assumed

'

'

'

'

'

'

'

'

0

1,481,535

0

'

First Ipswich Bancorp:

'

'

'

'

'

'

'

'

'

'

'

'

Acquisition

'

'

'

'

'

'

'

'

'

'

'

'

Fair value of assets acquired, net of cash and cash equivalents acquired

'

'

'

'

'

'

'

'

0

0

246,186

'

Fair value of liabilities assumed

'

'

'

'

'

'

'

'

0

0

251,978

'

Parent Company

'

'

'

'

'

'

'

'

'

'

'

'

ASSETS

'

'

'

'

'

'

'

'

'

'

'

'

Cash and due from banks

12,438

'

'

'

4,547

'

'

'

12,438

4,547

'

'

Short-term investments

33

'

'

'

33

'

'

'

33

33

'

'

Total cash and cash equivalents

12,471

'

'

'

4,580

'

'

'

12,471

4,580

640

'

Restricted equity securities

100

'

'

'

100

'

'

'

100

100

'

'

Loan to Brookline Bank ESOP

2,252

'

'

'

2,502

'

'

'

2,252

2,502

'

'

Premises and equipment, net

11,850

'

'

'

8,202

'

'

'

11,850

8,202

'

'

Deferred tax asset

0

'

'

'

1,879

'

'

'

0

1,879

'

'

Investment in subsidiaries, at equity

575,375

'

'

'

592,961

'

'

'

575,375

592,961

'

'

Goodwill

35,267

'

'

'

35,267

'

'

'

35,267

35,267

'

'

Other assets

6,185

'

'

'

1,893

'

'

'

6,185

1,893

'

'

Total assets

643,500

'

'

'

647,384

'

'

'

643,500

647,384

'

'

Liabilities and Stockholders' Equity

'

'

'

'

'

'

'

'

'

'

'

'

Demand checking accounts

0

'

'

'

41

'

'

'

0

41

'

'

Borrowed funds

9,163

'

'

'

12,091

'

'

'

9,163

12,091

'

'

Deferred tax liability

1,195

'

'

'

0

'

'

'

1,195

0

'

'

Accrued expenses and other liabilities

19,275

'

'

'

23,155

'

'

'

19,275

23,155

'

'

Total liabilities

29,633

'

'

'

35,287

'

'

'

29,633

35,287

'

'

Stockholders' equity

'

'

'

'

'

'

'

'

'

'

'

'

Common stock

757

'

'

'

757

'

'

'

757

757

'

'

Additional paid-in capital

617,538

'

'

'

618,426

'

'

'

617,538

618,426

'

'

Retained earnings, partially restricted

64,903

'

'

'

53,358

'

'

'

64,903

53,358

'

'

Accumulated other comprehensive (loss) income

-7,915

'

'

'

3,483

'

'

'

-7,915

3,483

'

'

Treasury stock, at cost; 5,171,985 and 5,373,733 shares, respectively

'

'

'

'

-62,107

'

'

'

'

-62,107

'

'

Treasury stock, shares

5,171,985

'

'

'

5,373,733

'

'

'

5,171,985

5,373,733

'

'

Unallocated common stock held by ESOP; 291,666 shares and 333,918 shares, respectively

-1,590

'

'

'

-1,820

'

'

'

-1,590

-1,820

'

'

Unallocated common stock held by ESOP, shares

291,666

'

'

'

333,918

'

'

'

291,666

333,918

'

'

Total Brookline Bancorp, Inc. Stockholders' equity

613,867

'

'

'

612,097

'

'

'

613,867

612,097

'

'

Total liabilities and stockholders' equity

643,500

'

'

'

647,384

'

'

'

643,500

647,384

'

'

Interest and dividend income:

'

'

'

'

'

'

'

'

'

'

'

'

Dividend income from subsidiaries

'

'

'

'

'

'

'

'

30,000

30,000

167,003

'

Short-term investments

'

'

'

'

'

'

'

'

0

0

1

'

Loan to Brookline Bank ESOP

'

'

'

'

'

'

'

'

205

227

249

'

Total interest and dividend income

'

'

'

'

'

'

'

'

30,205

30,227

167,253

'

Interest expense:

'

'

'

'

'

'

'

'

'

'

'

'

Borrowed funds and subordinated debt

'

'

'

'

'

'

'

'

442

589

91

'

Net interest income

'

'

'

'

'

'

'

'

29,763

29,638

167,162

'

Non-interest expense:

'

'

'

'

'

'

'

'

'

'

'

'

Compensation and employee benefits

'

'

'

'

'

'

'

'

2,305

11,302

0

'

Occupancy

'

'

'

'

'

'

'

'

16

0

0

'

Equipment and data processing

'

'

'

'

'

'

'

'

4,263

1,395

0

'

Directors' fees

'

'

'

'

'

'

'

'

590

580

225

'

Franchise taxes

'

'

'

'

'

'

'

'

223

175

180

'

Professional services

'

'

'

'

'

'

'

'

583

2,773

1,758

'

Advertising and marketing

'

'

'

'

'

'

'

'

6

11

0

'

Other

'

'

'

'

'

'

'

'

2,386

2,477

229

'

Total non-interest expense

'

'

'

'

'

'

'

'

10,372

18,713

2,392

'

Income before income taxes

'

'

'

'

'

'

'

'

19,391

10,925

164,770

'

(Credit) provision for income taxes

'

'

'

'

'

'

'

'

-4,035

-7,050

285

'

Income before distributions in excess of net income of subsidiaries

'

'

'

'

'

'

'

'

23,426

17,975

164,485

'

Distributions less than (in excess of) net income of subsidiaries

'

'

'

'

'

'

'

'

11,960

19,167

-137,227

'

Net income attributable to Brookline Bancorp, Inc.

'

'

'

'

'

'

'

'

35,386

37,142

27,600

'

Cash flows from operating activities:

'

'

'

'

'

'

'

'

'

'

'

'

Net income attributable to Brookline Bancorp, Inc.

'

'

'

'

'

'

'

'

35,386

37,142

27,600

'

Adjustments to reconcile net income to net cash provided from operating activities:

'

'

'

'

'

'

'

'

'

'

'

'

Distributions (less than) in excess of net income of subsidiaries

'

'

'

'

'

'

'

'

-11,960

-19,167

136,885

'

Other operating activities, net

'

'

'

'

'

'

'

'

16,555

-5,617

1,202

'

Net cash provided from operating activities

'

'

'

'

'

'

'

'

39,981

12,358

166,029

'

Cash flows from investing activities:

'

'

'

'

'

'

'

'

'

'

'

'

Acquisitions, net of cash and cash equivalents acquired

'

'

'

'

'

'

'

'

0

-89,258

-19,729

'

Monies in escrow - Bancorp Rhode Island, Inc. acquisition

'

'

'

'

'

'

'

'

0

112,983

-112,983

'

Repayment of ESOP loan by Brookline Bank

'

'

'

'

'

'

'

'

250

250

250

'

Purchase of restricted equity securities

'

'

'

'

'

'

'

'

0

-100

0

'

Purchase of premises and equipment

'

'

'

'

'

'

'

'

-5,458

-8,557

0

'

Net cash used in investing activities

'

'

'

'

'

'

'

'

-5,208

15,318

-132,462

'

Cash flows from financing activities:

'

'

'

'

'

'

'

'

'

'

'

'

Increase in demand checking, NOW, savings and money market accounts

'

'

'

'

'

'

'

'

-41

41

0

'

Payment of dividends on common stock

'

'

'

'

'

'

'

'

-23,841

-23,777

-19,964

'

Repayment of subordinated and other debt

'

'

'

'

'

'

'

'

-3,000

0

-13,985

'

Income tax benefit from vesting of recognition and retention plan shares and dividend distributions on allocated ESOP plans

'

'

'

'

'

'

'

'

0

0

79

'

Net cash provided from financing activities

'

'

'

'

'

'

'

'

-26,882

-23,736

-33,870

'

Net increase (decrease) in cash and cash equivalents

'

'

'

'

'

'

'

'

7,891

3,940

-303

'

Cash and cash equivalents at beginning of year

'

'

'

4,580

'

'

'

640

4,580

640

943

'

Cash and cash equivalents at end of year

12,471

'

'

'

4,580

'

'

'

12,471

4,580

640

'

Cash paid during the year for:

'

'

'

'

'

'

'

'

'

'

'

'

Interest on subordinated debt

'

'

'

'

'

'

'

'

480

795

0

'

Income taxes

'

'

'

'

'

'

'

'

19,137

16,981

0

'

Parent Company | Bancorp Rhode Island, Inc.:

'

'

'

'

'

'

'

'

'

'

'

'

Acquisition

'

'

'

'

'

'

'

'

'

'

'

'

Fair value of assets acquired, net of cash and cash equivalents acquired

'

'

'

'

'

'

'

'

0

1,571,817

0

'

Fair value of liabilities assumed

'

'

'

'

'

'

'

'

0

1,481,535

0

'

Parent Company | First Ipswich Bancorp:

'

'

'

'

'

'

'

'

'

'

'

'

Acquisition

'

'

'

'

'

'

'

'

'

'

'

'

Fair value of assets acquired, net of cash and cash equivalents acquired

'

'

'

'

'

'

'

'

0

0

246,186

'

Fair value of liabilities assumed

'

'

'

'

'

'

'

'

$0

$0

$251,978

'

Quarterly_Results_of_Operation2

Quarterly Results of Operations (Unaudited) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information Disclosure [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Interest and dividend income	$51,049	$50,823	$52,900	$51,612	$52,976	$55,394	$51,839	$52,991	$206,384	$213,200	$140,535
Interest expense	7,275	7,411	7,537	7,943	8,412	8,983	9,080	9,357	30,166	35,832	30,336
Net interest income	43,774	43,412	45,363	43,669	44,564	46,411	42,759	43,634	176,218	177,368	110,199
Provision for credit losses	3,887	2,748	2,439	1,855	3,101	2,862	6,678	3,247	10,929	15,888	3,631
Provision for credit losses	39,887	40,664	42,924	41,814	41,463	43,549	36,081	40,387	165,289	161,480	106,568
Loss on investment in affordable housing projects	-318	-558	-624	-312	-239	-73	-244	-138	-1,812	-694	-671
Gain on sales of securities, net	397	0	0	0	129	0	797	0	397	926	80
Gain on sales of loans and leases	'	'	'	'	1,898	0	0	0	0	1,898	0
Other non-interest income	3,828	4,011	3,762	3,639	4,716	3,858	4,168	3,733	'	'	'
Amortization of identified intangible assets	-1,127	-1,154	-1,177	-1,165	-1,797	-1,271	-1,271	-1,283	-4,623	-5,622	-1,570
Other non-interest expense	-30,193	-28,399	-29,638	-29,607	-27,072	-29,165	-27,350	-31,166	-11,261	-11,101	-6,787
Income before provision for income taxes	12,474	14,564	15,247	14,369	19,098	16,898	12,181	11,533	56,654	59,710	48,705
Provision for income taxes	4,325	4,645	5,382	5,129	6,868	5,176	4,398	4,899	19,481	21,341	19,886
Net income before noncontrolling interest in subsidiary	8,149	9,919	9,865	9,240	12,230	11,722	7,783	6,634	37,173	38,369	28,819
Less net income attributable to noncontrolling interest in subsidiary	495	490	375	427	367	321	254	285	1,787	1,227	1,219
Net income attributable to Brookline Bancorp, Inc.	$7,654	$9,429	$9,490	$8,813	$11,863	$11,401	$7,529	$6,349	$35,386	$37,142	$27,600
Earnings per common share attributable to Brookline Bancorp, Inc.:	'	'	'	'	'	'	'	'	'	'	'
Basic (in dollars per share)	$0.11	$0.14	$0.14	$0.13	$0.17	$0.16	$0.11	$0.09	$0.51	$0.53	$0.47
Diluted (in dollars per share)	$0.11	$0.13	$0.14	$0.13	$0.17	$0.16	$0.11	$0.09	$0.51	$0.53	$0.47
Average common shares outstanding:	'	'	'	'	'	'	'	'	'	'	'
Basic (in shares)	69,862,175	69,830,953	69,774,703	69,762,784	69,742,225	69,716,283	69,677,656	69,664,619	69,808,164	69,702,417	58,633,627
Diluted (in shares)	69,951,683	69,913,765	69,833,541	69,830,630	69,799,324	69,754,473	69,715,890	69,665,873	69,883,924	69,746,256	58,636,431
Common stock price:	'	'	'	'	'	'	'	'	'	'	'
High (in dollars per share)	$9.58	$10.08	$9.14	$9.39	$8.90	$9.25	$9.49	$9.78	'	'	'
Low (in dollars per share)	$8.72	$8.81	$8.23	$8.66	$7.54	$8.13	$8.46	$8.37	'	'	'
Dividends paid:	'	'	'	'	'	'	'	'	'	'	'
Per share (in dollars per share)	$0.09	$0.09	$0.09	$0.09	$0.09	$0.09	$0.09	$0.09	'	'	'
Payout ratio	77.88%	65.38%	60.71%	65.38%	50.21%	52.24%	79.08%	93.76%	'	'	'