Randolph Bancorp (RNDB) 10-Q 10 Nov 16 2016 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2016	Nov. 10, 2016
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q3
Trading Symbol	RNDB
Entity Registrant Name	Randolph Bancorp, Inc.
Entity Central Index Key	1,667,161
Current Fiscal Year End Date	--12-31
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		5,868,726

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Assets
Cash and due from banks	$ 4,917	$ 2,721
Interest-bearing deposits	22,076	1,925
Total cash and cash equivalents	26,993	4,646
Certificates of deposit	3,675	4,675
Securities available for sale, at fair value	70,877	62,267
Loans held for sale, at fair value at September 30, 2016 and lower of cost or fair value at December 31, 2015	29,092	2,870
Loans, net of allowance for loan losses of $3,096 and $3,239, respectively	327,519	285,151
Federal Home Loan Bank stock, at cost	2,368	2,728
Accrued interest receivable	1,067	1,065
Mortgage servicing rights	9,351	2,567
Premises and equipment, net	6,309	2,891
Bank-owned life insurance	7,852	9,620
Foreclosed real estate	353	500
Other assets	4,101	4,183
Total assets	489,557	383,163
Deposits:
Non-interest bearing	55,129	37,968
Interest bearing	300,913	271,227
Total deposits	356,042	309,195
Federal Home Loan Bank advances	36,802	34,914
Mortgagors' escrow accounts	2,053	1,445
Post-employment benefit obligations	2,854	3,294
Other liabilities	5,954	1,856
Total liabilities	403,705	350,704
Stockholders' Equity:
Preferred stock, no par value; authorized: 1,000,000 shares; issued: none
Common stock, $.01 par value; authorized: 15,000,000 shares; issued and outstanding: 5,868,726 shares at September 30, 2016 and none at December 31, 2015	59
Additional paid-in capital	56,288
Retained earnings	33,207	32,198
ESOP-Unearned compensation	(4,601)
Accumulated other comprehensive income, net of tax	899	261
Total stockholders' equity	85,852	32,459
Total liabilities and stockholders' equity	$ 489,557	$ 383,163

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Statement Of Financial Position [Abstract]
Loans, allowance for loan losses	$ 3,096	$ 3,239
Preferred stock, par value
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	15,000,000	15,000,000
Common stock, shares issued	5,868,726	0
Common stock, shares outstanding	5,868,726	0

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Interest and dividend income:
Loans	$ 3,434	$ 2,751	$ 8,982	$ 7,763
Securities-taxable	282	396	908	1,185
Securities-tax exempt	90	101	277	312
Interest-bearing deposits and certificates of deposit	70	17	124	48
Total interest and dividend income	3,876	3,265	10,291	9,308
Interest expense:
Deposits	388	292	1,033	879
Federal Home Loan Bank advances	67	52	185	109
Total interest expense	455	344	1,218	988
Net interest income	3,421	2,921	9,073	8,320
Provision (credit) for loan losses	(160)	(153)	(98)	(28)
Net interest income after provision (credit) for loan losses	3,581	3,074	9,171	8,348
Non-interest income:
Customer service fees	369	408	1,122	1,178
Net gain on sales of mortgage loans	5,401	755	7,140	1,945
Mortgage servicing	(95)	79	74	175
Gain (loss) on sales/calls of securities and impairment write-downs, net	100	(261)	162	(268)
Increase in cash surrender value of life insurance	36	59	140	180
Gain on life insurance settlements		402	486	402
Bargain purchase gain	1,451		1,451
Other	98	8	173	17
Total non-interest income	7,360	1,450	10,748	3,629
Non-interest expenses:
Salaries and employee benefits	5,348	2,538	9,931	6,963
Occupancy and equipment	691	423	1,448	1,355
Data processing	209	263	595	759
Professional fees	393	231	983	743
Marketing	135	83	307	257
Foreclosed real estate, net	5		162	121
FDIC insurance	74	77	213	222
Charitable foundation contribution	2,275		2,275
Merger and integration costs	514	517	664	517
Other	1,008	754	2,329	2,058
Total non-interest expenses	10,652	4,886	18,907	12,995
Income (loss) before income taxes	289	(362)	1,012	(1,018)
Income tax expense (benefit)		(1)	3	(5)
Net income (loss)	$ 289	$ (361)	$ 1,009	$ (1,013)
Weighted average common shares outstanding (basic and diluted)	5,403,923
Earnings per common share (basic and diluted)	$ 0.05

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Net income (loss)	$ 289	$ (361)	$ 1,009	$ (1,013)
Securities available for sale:
Unrealized holding gains (losses)	(257)	318	792	131
Reclassification adjustment for net (gains) losses and impairment write-downs realized in income	(100)	261	(162)	268
Net unrealized gains (losses)	(357)	579	630	399
Related tax effects		0		0
Net-of-tax amount	(357)	579	630	399
Post-retirement benefit plans:
Post-retirement benefit plans	3	304	8	383
Related tax effects		15		20
Net-of-tax amount	3	319	8	403
Other comprehensive income, Net of Tax	(354)	898	638	802
Comprehensive income (loss)	(65)	537	1,647	(211)
Defined Benefit Pension Plan [Member]
Post-retirement benefit plans:
Reclassification adjustment for actuarial losses recognized		292		344
Post-retirement benefit plans		292		344
Supplemental Retirement Plan [Member]
Post-retirement benefit plans:
Gain arising during the period	7	5	25	16
Post-retirement benefit plans	3	12	8	39
Prior service (credits) costs recognized	$ (4)	$ 7	$ (17)	$ 23

Consolidated Statements Changes

Consolidated Statements Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Initial Public Offering [Member]	Randolph Savings Charitable Foundation [Member]	Common Stock [Member]	Common Stock [Member]Initial Public Offering [Member]	Common Stock [Member]Randolph Savings Charitable Foundation [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member]Initial Public Offering [Member]	Additional Paid-in Capital [Member]Randolph Savings Charitable Foundation [Member]	Retained Earnings [Member]	Unearned Compensation ESOP [Member]	Accumulated Other Comprehensive Income [Member]
Beginning balance at Dec. 31, 2014	$ 33,656									$ 32,952		$ 704
Net income (loss)	(1,013)									(1,013)
Other comprehensive income	802											802
Ending balance at Sep. 30, 2015	33,445									31,939		1,506
Beginning balance at Dec. 31, 2014	33,656									32,952		704
Ending balance at Dec. 31, 2015	32,459									32,198		261
Net income (loss)	1,009									1,009
Other comprehensive income	638											638
Issuance of common stock for initial public offering, value		$ 54,501	$ 1,820		$ 57	$ 2		$ 54,444	$ 1,818
Issuance of common stock for initial public offering, shares					5,686,750	181,976
Stock purchased by ESOP	(4,695)										$ (4,695)
ESOP shares committed to be released	120						$ 26				94
Ending balance at Sep. 30, 2016	$ 85,852			$ 59			$ 56,288			$ 33,207	$ (4,601)	$ 899
Ending balance, shares at Sep. 30, 2016				5,868,726

Consolidated Statements Change7

Consolidated Statements Changes in Stockholders' Equity (Parenthetical) $ in Thousands	Sep. 30, 2016USD ($)
Initial Public Offering [Member]
Common stock issuance expenses	$ 2,367

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Cash flows from operating activities:
Net income (loss)	$ 1,009	$ (1,013)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Provision (credit) for loan losses	(98)	(28)
Bargain purchase gain	(1,451)
Loans originated for sale	(245,642)	(80,651)
Principal balance of loans sold	246,079	81,115
Net amortization of securities	110	94
Net change in deferred loan costs and fees	103	(162)
Net (gain) loss on sales/calls of securities and impairment write-downs	(162)	268
Depreciation and amortization	353	552
Impairment write-downs on foreclosed real estate	150	100
Gain on life insurance settlements, net	(486)	(293)
Charitable foundation contribution	1,820
ESOP expense	120
Increase in cash surrender value of life insurance	(120)	(181)
Net increase in mortgage servicing rights	(568)	(106)
Other, net	2,812	(854)
Net cash provided by (used in) operating activities	4,029	(1,159)
Cash flows from investing activities:
Redemption (purchases) of certificates of deposit	1,000	(1,960)
Securities available for sale:
Sales	2,521	318
Calls/maturities	6,970	2,756
Purchases	(21,745)	(549)
Principal payments on mortgage-backed securities	4,335	5,979
Loan originations, net of principal repayments	(10,554)	(33,450)
Loans purchased	(572)	(688)
Redemption (purchases) of Federal Home Loan Bank stock	1,009	(925)
Proceeds from sale of building	1,231
Proceeds from life insurance settlements	2,157	927
Acquisition of First Eastern, net of cash acquired	(10,956)
Purchases of premises and equipment	(674)	(401)
Net cash used in investing activities	(25,278)	(27,993)
Cash flows from financing activities:
Net increase in deposits	5,057	7,566
Proceeds from Federal Home Loan Bank advances	9,838	39,730
Repayments of Federal Home Loan Bank advances	(21,138)	(19,697)
Net decrease in mortgagors' escrow accounts	33	81
Net proceeds from the issuance of common stock	54,501
Acquisition of common stock by ESOP	4,695
Deferred stock offering costs		(321)
Net cash provided by financing activities	43,596	27,359
Net change in cash and cash equivalents	22,347	(1,793)
Cash and cash equivalents at beginning of period	4,646	5,203
Cash and cash equivalents at end of period	26,993	3,410
Supplemental cash flow information:
Interest paid on deposits and borrowed funds	1,222	979
Income taxes paid	$ 7	$ 6

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Basis of Presentation	NOTE 1 – BASIS OF PRESENTATION Overview Randolph Bancorp, a Massachusetts-chartered mutual holding company (“Bancorp”) and the parent company of Randolph Savings Bank (the “Bank”), adopted a plan of conversion (the “Plan of Conversion”) in January 2016 which was subsequently approved by Bancorp’s Corporators in May 2016. Under the Plan of Conversion, Bancorp would convert from a mutual to a stock holding company in a series of transactions in which Randolph Bancorp, Inc. (together with its consolidated subsidiaries, the “Company” unless the context requires another meaning) a recently formed subsidiary of Bancorp, would be the surviving entity. On July 1, 2016, the mutual-to-stock transaction was completed and the Company sold 5,686,750 shares of its common stock, representing the adjusted maximum of the offering range, at $10.00 per share, for gross proceeds of $56,867,500, including the sale of 469,498 shares to the Bank’s newly formed employee stock ownership plan (“ESOP”). The ESOP’s shares were funded by a loan from the Company to be repaid over 25 years with interest at the prime rate. The direct costs of the Company’s stock offering were deducted from the proceeds of the offering and amounted to $2,367,000. In connection with the Plan of Conversion, the Company established The Randolph Savings Charitable Foundation, Inc. (the “Foundation”). The Foundation was funded with 181,976 shares of the Company’s common stock and $455,000 in cash. In July 2016, the Company recognized expense of $2,274,700 for this contribution. The Company and the Bank are required to restrict their net worth by establishing liquidation accounts (collectively, the “liquidation account”) for the benefit of eligible account holders who continue to maintain deposit accounts at the Bank after the conversion. The liquidation account will be reduced annually to the extent eligible depositors reduce their qualifying deposits and cannot be increased thereafter with additional deposits. In the event of a complete liquidation of the Bank, each eligible account holder would be entitled to receive a distribution from the liquidation account in an amount proportionate to the adjusted qualifying account balances then held. Neither the Company nor the Bank may declare or pay a cash dividend on its common stock if such dividend would cause its regulatory capital to be reduced below the amount required to maintain the liquidation account. Bancorp entered into a merger agreement in September 2015 under which it would acquire First Eastern Bankshares Corporation (“Bankshares”) and its wholly-owned subsidiary First Federal Savings Bank of Boston (“First Federal” and together with Bankshares, “First Eastern”) in a transaction accounted for as a business combination. Before the acquisition, First Eastern was actively engaged in the mortgage banking business as an originator, seller and servicer of residential mortgage loans. On July 1, 2016, the Company completed the acquisition of First Eastern. See Note 2 for additional information. Basis of Financial Statement Presentation The accompanying unaudited interim consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. These financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) for interim financial reporting and with the instructions to Form 10-Q and Article 10 of Regulation S-X issued by the Securities and Exchange Commission (“SEC”). Accordingly, the accompanying interim financial statements do not include all information required under GAAP for complete financial statements. In the opinion of management, all adjustments considered necessary for a fair presentation of the financial statements, primarily consisting of normal recurring adjustments, have been included. The operating results for the three and nine months ended September 30, 2016 are not necessarily indicative of the results to be expected for the year ending December 31, 2016 or any other interim period. For further information, refer to the consolidated financial statements and notes thereto included in the prospectus of Randolph Bancorp, Inc. dated May 13, 2016, as filed with the SEC.

Acquisition

Acquisition	9 Months Ended
	Sep. 30, 2016
Business Combinations [Abstract]
Acquisition	NOTE 2 – ACQUISITION On July 1, 2016, the Company acquired all of the outstanding common stock of Bankshares for cash of $13.9 million. First Eastern operated eight residential loan production offices in eastern Massachusetts and New Hampshire and a retail banking branch in downtown Boston. As a result of the transaction, Bankshares merged into Randolph Bancorp, Inc. and First Federal merged into Randolph Savings Bank. This business combination significantly increases the Company’s mortgage banking operations. During the year ended December 31, 2015 and the six months ended June 30, 2016, First Eastern sold $417.6 million and $175.2 million, respectively, of residential mortgage loans in the secondary mortgage market. The results of First Eastern’s operations are included in the Company’s consolidated statement of operations from the date of acquisition. First Eastern’s assets and liabilities were recorded at their fair value as of the date of acquisition based on management’s preliminary estimates using currently available information. Prior to the end of the one year measurement period for finalizing the purchase price allocation, if information becomes available which would indicate adjustments are required, such adjustments will be included in the purchase price allocation in the reporting period in which the adjustment amounts are determined. Cash consideration paid, and fair values of First Eastern’s assets acquired and liabilities assumed, along with the resulting bargain purchase gain, are summarized in the following table (in thousands): Fair Value As Acquired Adjustments As Recorded (In thousands) Cash and cash equivalents $ 2,951 $ — $ 2,951 Loans held for sale 26,209 450 (a) 26,659 Loans 30,824 482 (b) 31,306 Mortgage servicing rights 4,396 1,820 (c) 6,216 Premises and equipment 1,566 1,534 (d) 3,100 Core deposit intangible — 118 (e) 118 Goodwill 789 (789 ) (f) - Other assets 2,046 (55 ) (g) 1,991 Deposits (41,737 ) (53 ) (h) (41,790 ) Federal Home Loan Bank advances (13,128 ) (60 ) (h) (13,188 ) Other liabilities (1,917 ) (88 ) (i) (2,005 ) Total identifiable net assets $ 11,999 $ 3,359 15,358 Cash consideration paid to seller 13,907 Bargain purchase gain $ 1,451 Explanation of the fair value adjustments is as follows: (a) The adjustment represents the write-up of the book value of loans held for sale to their estimated fair value based on current selling prices, including the value of their servicing rights. (b) The adjustment represents the write-up of the book value of loans, to their estimated fair value based on current interest rates and expected cash flows, which includes an estimate of expected loan losses inherent in the portfolio. The balance of impaired loans was not significant. (c) The adjustment represents the write-up of the book value of mortgage servicing rights associated with $789.3 million of serviced loans to their estimated fair value based on an independent appraisal. The fair value was determined based on the discounted present value of estimated future net servicing income using market-based assumptions including prepayment speeds, costs of servicing, risk characteristics and interest rates. (d) The adjustment represents the write-up of the Boston retail branch based on an independent appraisal. (e) This amount represents the estimated fair value of core deposit relationships (equal to 1.1% of core deposits) based on an independent appraisal. (f) The adjustment eliminates existing goodwill. (g) The adjustment eliminates deferred origination costs for loans-in-process. (h) The adjustments represent the write-up of the book value of term certificate accounts and FHLB advances based on interest rates currently offered on instruments having similar remaining maturities. (i) The adjustment represents the fair value of forward loan sale commitments written on a best efforts basis. The bargain purchase gain was recognized during the quarter ended September 30, 2016 and is presented in the accompanying statement of operations as a separate component of non-interest income. This gain is primarily attributable to the write-ups of the mortgage servicing rights and premises and equipment to fair value as determined by independent third-party specialists based on market assumptions that were reviewed for reasonableness. Direct acquisition and merger integration costs of the First Eastern business combination are being expensed as incurred and are presented separately in the accompanying statements of operations. Costs incurred in 2015 consist principally of legal fees in completing negotiation of the purchase and sale agreement. Costs incurred during the nine months ended September 30, 2016 consist of retention bonuses, systems de-conversion costs as well as legal and consulting fees. Additional merger integration costs are expected to be incurred through the second quarter of 2017. The following table presents selected unaudited pro forma financial information assuming that the acquisition was completed as of January 1, 2015. The pro forma amounts reflect adjustments related to: (a) reversal of non-recurring merger and integration costs; (b) reversal of a special bonus of $1.6 million paid in June 2016 to First Eastern executives in connection with the merger; (c) amortization and accretion of acquisition accounting fair value adjustments; and (d) reversal of the bargain purchase gain. No provision (benefit) for income taxes is included in the determination of pro forma net income (loss) for the periods presented due to the Company’s net operating loss carryforward position. Furthermore, the unaudited pro forma financial information do not reflect management’s estimate of any revenue enhancement opportunities or anticipated potential cost savings nor any adjustments related to the stock offering completed on July 1, 2016. The unaudited pro forma financial information is presented for illustrative purposes only and is not necessarily indicative of the combined financial results of the Company and First Eastern had the acquisition transaction actually been completed at the beginning of the periods presented, nor does it indicate future results for any interim or annual period. Pro forma basic and diluted earnings (loss) per common share are not presented as such information is not being presented as part of our historical financial statements for the periods being presented due to the completion of the stock offering on July 1, 2016. Unaudited pro forma financial information for the nine months ended September 30, 2016 and 2015 is as follows (in thousands): 2016 2015 Net Interest Income $ 10,054 $ 10,002 Non-interest Income 14,652 11,212 Net Income (Loss) 422 (243 ) Included in net interest income and non-interest income for both the three and nine month periods ended September 30, 2016 were $537,000 and $4,039,000, respectively, associated with First Eastern. For these same periods, First Eastern’s contribution to consolidated net income amounted to $925,000. Conversion of the core processing system for First Eastern is scheduled for the fourth quarter of 2016 after which separate revenue and earnings information for First Eastern will no longer be available.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Accumulated Other Comprehensive Income	NOTE 3 – ACCUMULATED OTHER COMPREHENSIVE INCOME Accounting principles generally require that recognized revenue, expenses, gains and losses be included in net income (loss). Although certain changes in assets and liabilities are reported as a separate component of stockholders’ equity, such items, along with net income (loss), are components of comprehensive income (loss). The components of accumulated other comprehensive income, included in total stockholders’ equity, are as follows: September 30, December 31, 2016 2015 (In thousands) Securities available for sale: Net unrealized gain $ 1,516 $ 886 Tax effect (423 ) (423 ) Net-of-tax amount 1,093 463 Supplemental retirement plan Unrecognized net actuarial loss (718 ) (743 ) Unrecognized net prior service credit 581 598 (137 ) (145 ) Tax effect (57 ) (57 ) Net-of-tax amount (194 ) (202 ) Accumulated other comprehensive income $ 899 $ 261

Recent Accounting Pronouncement

Recent Accounting Pronouncements	9 Months Ended
	Sep. 30, 2016
Accounting Changes And Error Corrections [Abstract]
Recent Accounting Pronouncements	NOTE 4 – RECENT ACCOUNTING PRONOUNCEMENTS In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-02, Leases In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses

Securities Available for Sale

Securities Available for Sale	9 Months Ended
	Sep. 30, 2016
Investments Debt And Equity Securities [Abstract]
Securities Available for Sale	NOTE 5 – SECURITIES AVAILABLE FOR SALE The amortized cost and fair value of securities available for sale, including gross unrealized gains and losses, are as follows: Gross Gross Amortized Unrealized Unrealized Fair Cost Gains Losses Value (In thousands) September 30, 2016 Debt securities: U.S. Government-sponsored enterprises $ 3,999 $ 140 $ — $ 4,139 Corporate 3,054 91 (4 ) 3,141 Municipal 13,870 516 (2 ) 14,384 Residential mortgage-backed securities: U.S. Government-sponsored enterprises 29,769 512 (5 ) 30,276 U.S. Government-guaranteed 11,481 173 — 11,654 Commercial mortgage-backed securities: U.S. Government-guaranteed 6,643 88 — 6,731 Total debt securities 68,816 1,520 (11 ) 70,325 Mutual fund 545 7 — 552 Total securities available for sale $ 69,361 $ 1,527 $ (11 ) $ 70,877 December 31, 2015 Debt securities: U.S. Government-sponsored enterprises $ 6,886 $ 159 $ (12 ) $ 7,033 Corporate 4,250 78 (48 ) 4,280 Municipal 15,327 472 (24 ) 15,775 Residential mortgage-backed securities: U.S. Government-sponsored enterprises 19,742 406 (120 ) 20,028 U.S. Government-guaranteed 7,276 50 — 7,326 Commercial mortgage-backed securities: U.S. Government-guaranteed 7,355 33 (108 ) 7,280 Total debt securities 60,836 1,198 (312 ) 61,722 Mutual fund 545 — — 545 Total securities available for sale $ 61,381 $ 1,198 $ (312 ) $ 62,267 The amortized cost and fair value of debt securities by contractual maturity at September 30, 2016 are presented below. Expected maturities will differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties. Amortized Fair Cost Value (In thousands) Within 1 year $ — $ — After 1 year through 5 years 13,931 14,349 After 5 years through 10 years 6,992 7,315 20,923 21,664 Mortgage-backed securities 47,893 48,661 $ 68,816 $ 70,325 Information pertaining to securities with gross unrealized losses, aggregated by investment category and length of time that individual securities have been in a continuous loss position, follows: Less Over Twelve Months Gross Gross Unrealized Fair Unrealized Fair Losses Value Losses Value September 30, 2016 (In thousands) Debt securities: Corporate $ — $ — $ (4 ) $ 1,004 Municipal — — (2 ) 486 Residential mortgage-backed securities: U.S. Government-sponsored (5 ) 5,243 — — Commercial mortgage-backed securities: U.S. Government-guaranteed — — — — Total debt securities $ (5 ) $ 5,243 $ (6 ) $ 1,490 December 31, 2015 Debt securities: U.S. Government-sponsored enterprises $ — $ — $ (12 ) $ 1,989 Corporate — — (48 ) 2,088 Municipal — — (24 ) 2,185 Residential mortgage-backed securities: U.S. Government-sponsored — — (120 ) 5,994 Commercial mortgage-backed securities: U.S. Government-guaranteed — — (108 ) 5,062 Total debt securities $ — $ — $ (312 ) $ 17,318 Management evaluates securities for other-than-temporary impairment at least on a quarterly basis, and more frequently when economic or market concerns warrant such evaluation. At September 30, 2016, 4 debt securities had unrealized losses with aggregate depreciation of less than 1% from the Company’s amortized cost basis. The Company currently does not believe it is probable that it will be unable to collect all amounts due according to the contractual terms of these investments. Therefore, it is expected that the bonds would not be settled at a price less than the par value of the investment. Because the Company does not intend to sell any debt securities and it is more likely than not that the Company will not be required to sell any debt securities before recovery of its amortized cost basis, it does not consider these investments to be other-than-temporarily impaired at September 30, 2016. When possible, management actively monitors the credit rating of the underlying issuer of the debt security. As of September 30, 2016 management did not identify any securities for which the credit rating had deteriorated since purchase.

Loans and Allowance for Loan Lo

Loans and Allowance for Loan Losses	9 Months Ended
	Sep. 30, 2016
Receivables [Abstract]
Loans and Allowance for Loan Losses	NOTE 6 – LOANS AND ALLOWANCE FOR LOAN LOSSES A summary of loan portfolio is as follows: September 30, 2016 December 31, 2015 (In thousands) Mortgage loans on real estate: Residential: One-to-four family $ 179,645 $ 166,483 Home equity loans and lines of credit 34,779 33,259 Commercial 87,332 74,911 Construction 22,913 7,807 324,669 282,460 Commercial and industrial 1,929 2,040 Consumer 2,812 2,602 Total loans 329,410 287,102 Allowance for loan losses (3,096 ) (3,239 ) Net deferred loan costs and fees, and purchase premiums 1,205 1,288 $ 327,519 $ 285,151 The following table summarizes the changes in the allowance for loan losses by portfolio segment for the three and nine months ended September 30, 2016 and 2015: Second Residential Mortgages Commercial Commercial 1-4 Family and Real Estate Construction and Industrial Consumer Total (In thousands) Three Months Ended September 30, 2016 Allowance at June 30, 2016 $ 1,046 $ 444 $ 1,520 $ 135 $ 36 $ 78 $ 3,259 Provision (credit) for loan losses 12 (15 ) (166 ) 9 3 (3 ) (160 ) Loans charged-off — — — — — (6 ) (6 ) Recoveries 2 — — — — 1 3 Balance at September 30, 2016 $ 1,060 $ 429 $ 1,354 $ 144 $ 39 $ 70 $ 3,096 Three Months Ended September 30, 2015 Allowance at June 30, 2015 $ 1,314 $ 542 $ 1,580 $ 128 $ 44 $ 45 $ 3,653 Provision (credit) for loan losses (21 ) (35 ) (103 ) (44 ) 28 22 (153 ) Loans charged-off (8 ) — — — (37 ) (3 ) (48 ) Recoveries 2 — — — 1 2 5 Balance at September 30, 2015 $ 1,287 $ 507 $ 1,477 $ 84 $ 36 $ 66 $ 3,457 Nine Months Ended September 30, 2016 Allowance at December 31, 2015 $ 1,076 $ 512 $ 1,402 $ 159 $ 37 $ 53 $ 3,239 Provision (credit) for loan losses (20 ) (83 ) (48 ) (15 ) 2 66 (98 ) Loans charged-off — — — — — (66 ) (66 ) Recoveries 4 — — — — 17 21 Balance at September 30, 2016 $ 1,060 $ 429 $ 1,354 $ 144 $ 39 $ 70 $ 3,096 Nine Months Ended September 30, 2015 Allowance at December 31, 2014 $ 1,368 $ 488 $ 1,539 $ 60 $ 51 $ 38 $ 3,544 Provision (credit) for loan losses (76 ) 19 (62 ) 24 20 47 (28 ) Loans charged-off (8 ) — — — (37 ) (32 ) (77 ) Recoveries 3 — — — 2 13 18 Balance at September 30, 2015 $ 1,287 $ 507 $ 1,477 $ 84 $ 36 $ 66 $ 3,457 Additional information pertaining to the allowance for loan losses at September 30, 2016 and December 31, 2015 is as follows: Second Residential Mortgages Commercial Commercial 1-4 Family and Real Estate Construction and Industrial Consumer Total September 30, 2016 (In thousands) Allowance for impaired loans $ 201 $ 4 $ 12 $ — $ — $ — $ 217 Allowance for non-impaired loans 859 425 1,342 144 39 70 2,879 Total allowance for loan losses $ 1,060 $ 429 $ 1,354 $ 144 $ 39 $ 70 $ 3,096 Impaired loans $ 5,605 $ 277 $ 956 $ — $ — $ — $ 6,838 Non-impaired loans 174,040 34,502 86,376 22,913 1,929 2,812 322,572 Total loans $ 179,645 $ 34,779 $ 87,332 $ 22,913 $ 1,929 $ 2,812 $ 329,410 December 31, 2015 Allowance for impaired loans $ 254 $ 2 $ 28 $ — $ — $ — $ 284 Allowance for non-impaired loans 822 510 1,374 159 37 53 2,955 Total allowance for loan losses $ 1,076 $ 512 $ 1,402 $ 159 $ 37 $ 53 $ 3,239 Impaired loans $ 4,961 $ 277 $ 1,449 $ — $ 16 $ — $ 6,703 Non-impaired loans 161,522 32,982 73,462 7,807 2,024 2,602 280,399 Total loans $ 166,483 $ 33,259 $ 74,911 $ 7,807 $ 2,040 $ 2,602 $ 287,102 The following is a summary of past due and non-accrual loans at September 30, 2016 and December 31, 2015: 30 - 59 Days Past Due 60 - 89 Days Past Due 90 Days or More Past Due Total Past Due Non-accrual Loans (In thousands) September 30, 2016 Residential one-to-four family $ 710 $ 419 $ — $ 1,129 $ 2,100 Home equity loans and lines of credit — 3 — 3 276 Commercial real estate — — — — — Construction — — — — — Commercial and industrial — — — — — Consumer — — — — — Total $ 710 $ 422 $ — $ 1,132 $ 2,376 December 31, 2015 Residential one-to-four family $ 403 $ 133 $ 46 $ 582 $ 2,022 Home equity loans and lines of credit — 247 — 247 30 Commercial real estate — — — — — Construction — — — — — Commercial and industrial — — — — 16 Consumer — — — — — Total $ 403 $ 380 $ 46 $ 829 $ 2,068 At September 30, 2016 and December 31, 2015, there were no loans past due 90 days or more and still accruing interest. The following is a summary of impaired loans at September 30, 2016 and December 31, 2015: Recorded Investment Unpaid Principal Balance Related Allowance (In thousands) September 30, 2016 Impaired loans without a valuation allowance: Residential one-to-four family $ 2,022 $ 2,022 $ — Home equity loans and lines of credit 247 247 — Commercial real estate 361 361 — Total 2,630 2,630 — Impaired loans with a valuation allowance: Residential one-to-four family 3,583 3,583 201 Home equity loans and lines of credit 30 30 4 Commercial real estate 595 595 12 Total 4,208 4,208 217 Total impaired loans $ 6,838 $ 6,838 $ 217 December 31, 2015 Impaired loans without a valuation allowance: Residential one-to-four family $ 874 $ 874 $ — Home equity loans and lines of credit 247 247 — Commercial real estate 422 422 — Commercial and industrial 16 16 — Total 1,559 1,559 — Impaired loans with a valuation allowance: Residential one-to-four family 4,088 4,088 254 Home equity loans and lines of credit 30 30 2 Commercial real estate 1,026 1,026 28 Total 5,144 5,144 284 Total impaired loans $ 6,703 $ 6,703 $ 284 Additional information pertaining to impaired loans follows: Average Interest Cash Basis Recorded Income Interest Investment Recognized Recognized (In thousands) Nine Months Ended September 30, 2016 Residential one-to-four family $ 5,165 $ 130 $ 49 Home equity loans and lines of credit 253 1 1 Commercial real estate 1,193 42 2 Commercial and industrial 5 1 1 Total $ 6,616 $ 174 $ 53 Nine Months Ended September 30, 2015 Residential one-to-four family $ 6,359 $ 170 $ 55 Home equity loans and lines of credit 24 1 1 Commercial real estate 6,194 214 7 Commercial and industrial 17 — — Total $ 12,594 $ 385 $ 63 Three Months Ended September 30, 2016 Residential one-to-four family $ 5,613 $ 45 $ 23 Home equity loans and lines of credit 276 — — Commercial real estate 971 12 1 Total $ 6,860 $ 57 $ 24 Three Months Ended September 30, 2015 Residential one-to-four family $ 6,139 $ 60 $ 22 Home equity loans and lines of credit — — 1 Commercial real estate 4,351 31 — Commercial and industrial 16 — — Total $ 10,506 $ 91 $ 23 No additional funds are committed to be advanced in connection with impaired loans. Troubled Debt Restructurings The Company periodically grants concessions to borrowers experiencing financial difficulties. At September 30, 2016, the Company had 24 residential real estate loans and 4 commercial real estate loans aggregating $5,367,000 and $683,000, respectively, which were subject to troubled debt restructuring agreements. At September 30, 2015, the Company had 26 residential real estate loans and 7 commercial real estate loans aggregating $6,113,000 and $4,027,000, respectively, which were subject to troubled debt restructuring agreements. As of September 30, 2016 and 2015, $6,050,000 and $10,140,000, respectively, in troubled debt restructurings were performing in accordance with the terms of the modified loan agreements. Included in such amounts are $1,714,000 and $2,334,000, respectively, that are being accounted for as non-accrual loans. The Company’s troubled debt restructurings consist primarily of interest rate concessions for periods of three months to thirty years for residential real estate loans, and for periods up to one year for commercial real estate loans. For the nine months ended September 30, 2016 the Company did not enter into any loan modifications meeting the criteria of a troubled debt restructuring. For the nine months ended September 30, 2015 the Company modified two loans meeting the criteria of a troubled debt restructuring having a loan balance of $434,000 with rate reductions ranging from 1% to 3%. Management performs a discounted cash flow calculation to determine the amount of impairment reserve required on each of the troubled debt restructurings. Any reserve required is recorded as part of the allowance for loan losses. During the three and nine months ended September 30, 2016 and 2015, there were no material changes to the allowance for loan losses as a result of loan modifications made which were considered a troubled debt restructuring. During the three and nine months ended September 30, 2016 and 2015, there were no troubled debt restructurings that defaulted (over 30 days past due) within twelve months of the restructure date. Credit Quality Information The Company utilizes an eight-grade internal loan rating system for commercial real estate, construction and commercial loans, as follows: Loans rated 1 – 3A are considered “pass” rated loans with low to average risk. Loans rated 4 are considered “special mention.” These loans are starting to show signs of potential weakness and are being closely monitored by management. Loans rated 5 are considered “substandard” and are inadequately protected by the current net worth and paying capacity of the obligors and/or the collateral pledged. There is a distinct possibility that the Company will sustain some loss if the weakness is not corrected. Loans rated 6 are considered “doubtful” and have all the weaknesses inherent in those classified substandard with the added characteristic that the weaknesses make collection or liquidation in full, on the basis of currently existing facts, highly questionable and improbable. Loans rated 7 are considered uncollectible (“loss”) and of such little value that their continuance as loans is not warranted. On an annual basis, or more often if needed, the Company formally reviews the ratings on all commercial real estate, construction and commercial and industrial loans. Annually, the Company engages an independent third party to review a significant portion of loans within these segments. Management uses the results of these reviews as part of its annual review process. The following table presents the Company’s loans by risk rating: September 30, 2016 December 31, 2015 Commercial Real Construction Commercial and Industrial Commercial Real Construction Commercial and Industrial (In thousands) Loans rated 1 - 3A $ 87,058 $ 22,913 $ 1,929 $ 73,517 $ 7,807 $ 2,006 Loans rated 4 64 — — 1,145 — — Loans rated 5 210 — — 249 — 34 $ 87,332 $ 22,913 $ 1,929 $ 74,911 $ 7,807 $ 2,040 Residential mortgages, home equity loans and lines of credit, and consumer loans are monitored for credit quality based primarily on their payment status. When one these loans becomes more than 90 days delinquent it is assigned an internal loan rating. At September 30, 2016, $897,000 in residential mortgages were rated as substandard and $1,418,000 in residential mortgages and $276,000 in home equity loans were rated as special mention. At December 31, 2015, $378,000 in residential mortgages were rated as substandard and $2,262,000 in residential mortgages and $277,000 in home equity loans were rated as special mention.

Loan Servicing

Loan Servicing	9 Months Ended
	Sep. 30, 2016
Transfers And Servicing [Abstract]
Loan Servicing	NOTE 7 - LOAN SERVICING Mortgage loans serviced for others are not included in the accompanying consolidated balance sheets. The unpaid principal balances of residential mortgage loans serviced for others were $1.2 billion and $317.2 million at September 30, 2016 and December 31, 2015, respectively. The following table summarizes the activity relating to mortgage servicing rights for the nine months ended September 30, 2016 and 2015 (in thousands): 2016 2015 Mortgage servicing rights: Balance at beginning of year $ 2,601 $ 2,445 Additions through originations 1,676 380 Additions through First Eastern acquisition 6,216 — Amortization (644 ) (274 ) Balance at end of period $ 9,849 $ 2,551 Valuation allowance: Balance at beginning of year $ 34 $ — Provision 464 — Balance at end of period $ 498 $ — Mortgage servicing rights, amortized cost $ 9,351 $ 2,551 Mortgage servicing rights, fair value $ 9,360 $ 2,842 As of July 1, 2016, First Eastern was servicing $789.3 million in residential mortgage loans. The estimated fair value of the related servicing rights was determined by a third party appraisal to be $6.2 million. This estimate was determined using a discount rate of 10% and projected annual prepayment speeds ranging from 6% to 28%. During the three months ended September 30, 2016, the Company increased the valuation allowance for its mortgage servicing rights by $416,000. This increase was necessitated by a decline in fair value caused by accelerated prepayments during the quarter as well as a forecast of accelerating future prepayments. In addition, the discount rate used was increased to 12% reflecting the expectations of current market participants.

On-Balance Sheet Derivative Ins

On-Balance Sheet Derivative Instruments and Hedging Activities	9 Months Ended
	Sep. 30, 2016
Derivative Instruments And Hedging Activities Disclosure [Abstract]
On-Balance Sheet Derivative Instruments and Hedging Activities	NOTE 8 - ON-BALANCE SHEET DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES Derivative Loan Commitments Mortgage loan commitments qualify as derivative loan commitments if the loan that will result from exercise of the commitment will be held for sale upon funding. The Company enters into commitments to fund residential mortgage loans at specified rates and times in the future, with the intention that these loans will subsequently be sold in the secondary market. Outstanding derivative loan commitments expose the Company to the risk that the price of the loans arising from exercise of the loan commitment might decline from inception of the rate lock to funding of the loan due to an increase in mortgage interest rates. If interest rates increase, the value of these loan commitments decreases. Conversely, if interest rates decrease, the value of these loan commitments increases. The notional amount of derivative loan commitments was $83,310,000 and $5,292,000 at September 30, 2016 and December 31, 2015, respectively. The fair value of such commitments was an asset of $1,447,000 and $93,000 as of September 30, 2016 and December 31, 2015, respectively, and is included in other assets in the consolidated balance sheets. Forward Loan Sale Commitments The Company utilizes both “mandatory delivery” and “best efforts” forward loan sale commitments to mitigate the risk of potential decreases in the values of loans that would result from the exercise of the derivative loan commitments. With a “mandatory delivery” contract, the Company commits to deliver a certain principal amount of mortgage loans to an investor at a specified price on or before a specified date. If the Company fails to deliver the amount of mortgages necessary to fulfill the commitment by the specified date, it is obligated to pay a “pair-off” fee, based on then-current market prices, to the investor to compensate the investor for the shortfall. With a “best efforts” contract, the Company commits to deliver an individual mortgage loan of a specified principal amount and quality to an investor if the loan to the underlying borrower closes. Generally, the price the investor will pay the seller for an individual loan is specified prior to the loan being funded (e.g. on the same day the lender commits to lend funds to a potential borrower). The Company does not account for best efforts contracts as derivative instruments, as such contracts do not require payment of a pair-off fee if the underlying mortgage loan does not close. The Company expects that these forward loan sale commitments will experience inverse changes in fair value to the change in fair value of derivative loan commitments. The notional amount of forward loan sale commitments was $91,180,000 (including $60,085,000 of mandatory delivery contracts) and $7,371,000 at September 30, 2016 and December 31, 2015, respectively. The fair value of such commitments was an asset of $33,000 and $14,000 at September 30, 2016 and December 31, 2015, respectively, included in other assets in the consolidated balance sheets and a liability of $201,000 at September 30, 2016 included in other liabilities in the consolidated balance sheet.

Employee Stock Ownership Plan

Employee Stock Ownership Plan	9 Months Ended
	Sep. 30, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Employee Stock Ownership Plan	NOTE 9 - EMPLOYEE STOCK OWNERSHIP PLAN In connection with our mutual-to-stock conversion and stock offering, the Company established an employee stock ownership plan (“ESOP) which acquired 469,498 shares of the Company’s common stock equaling 8% of the shares issued, including shares issued to the Randolph Savings Charitable Foundation. The ESOP is a tax-qualified retirement plan providing employees the opportunity to own Company stock. Company contributions to the ESOP are allocated to eligible participants on the basis of compensation, subject to federal tax limits. The number of shares to be allocated annually is 18,780 through 2040. Shares are committed to be released on a monthly basis and allocated as of December 31 each year. During the three and nine month periods ended September 30, 2016, 9,390 shares were committed to be released resulting in compensation expense, based on the fair value of the Company’s stock, of $120,200. The fair value of the 460,108 unallocated shares at September 30, 2016 was $6,271,300.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Earnings Per Share	NOTE 10 - EARNINGS PER SHARE Basic earnings per share represents net income divided by the weighted average of common shares outstanding during the period. Unallocated ESOP shares are not considered to be outstanding for purposes of computing earnings per share. There were no potentially dilutive common stock equivalents outstanding at September 30, 2016, hence diluted and basic earnings per share do not vary. The cost of shares issued to the ESOP, but not yet allocated to participants, is shown as a reduction of stockholders’ equity. During the quarter ended September 30, 2016, there were 5,868,726 shares outstanding while the average of unallocated ESOP shares totaled 464,803 resulting in a total of 5,403,923 shares being used to compute basic and diluted earnings per share. As shares were not outstanding throughout the 2015 periods and the nine months ended September 30, 2016, earnings (loss) per share are not presented for these periods.

Fair Value of Assets and Liabil

Fair Value of Assets and Liabilities	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Fair Value of Assets and Liabilities	NOTE 11 – FAIR VALUE OF ASSETS AND LIABILITIES Determination of fair value The Company uses fair value measurements to record fair value adjustments to certain assets and liabilities and to determine fair value disclosures. Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Fair value is best determined based upon quoted market prices. However, in many instances, there are no quoted market prices for the Company’s various assets and liabilities. In cases where quoted market prices are not available, fair values are based on estimates using present value or other valuation techniques. Those techniques are significantly affected by the assumptions used, including the discount rate and estimates of future cash flows. Accordingly, the fair value estimates may not be realized in an immediate settlement of the asset or liability. Effective July 1, 2016, the Company elected the fair value option pursuant to Accounting Standards Codification (“ASC”) 825, “Financial Instruments” for its residential mortgage loans being held for sale in the secondary market. ASC 825 allows for the irrevocable option to elect fair value accounting for the initial and subsequent measurement for certain financial assets and liabilities on a contract-by-contract basis that may otherwise not be required to be measured at fair value under other accounting standards. The Company elected the fair value option to better match changes in fair values of the loans with changes in the fair value of the forward loan sale commitments which are used to economically hedge them against changes in interest rates between the time an interest rate lock agreement is entered into with the borrower and the time the completed loan is sold. The aggregate fair value of the loans held for sale, the contractual balance of loans held for sale and the gain on loans held for sale totaled $29.1 million, $28.2 million and $911,000, respectively, at September 30, 2016. The gain on loans held for sale is reported as a component of net gains on sale of mortgage loans in the accompanying statement of operations for the three months ended September 30, 2016. The following methods and assumptions were used by the Company in estimating fair value disclosures: Cash and cash equivalents Certificates of deposit Securities Federal Home Loan Bank of Boston (“FHLBB”) stock Loans held for sale Loans Mortgage servicing rights Deposit liabilities FHLBB advances Accrued interest On-balance-sheet derivatives Off-balance sheet credit-related instruments Assets and liabilities measured at fair value on a recurring basis Assets and liabilities measured at fair value on a recurring basis are summarized below. There were no liabilities measured at fair value on a recurring basis at December 31, 2015. Total Level 1 Level 2 Level 3 Fair (In thousands) September 30, 2016 Assets: Securities available for sale: Debt securities $ — $ 70,325 $ — $ 70,325 Mutual fund — 552 — 552 Loans held for sale — 29,092 — 29,092 Derivative loan commitments — 1,447 — 1,447 Forward loan sale commitments — 33 — 33 Liabilities: Forward loan sale commitments — 201 — 201 December 31, 2015 Assets: Securities available for sale: Debt securities $ — $ 61,722 $ — $ 61,722 Mutual fund — 545 — 545 Derivative loan commitments — 93 — 93 Forward loan sale commitments — 14 — 14 Assets measured at fair value on a non-recurring basis The Company may also be required, from time to time, to measure certain other assets at fair value on a non-recurring basis in accordance with U.S. generally accepted accounting principles. These adjustments to fair value usually result from application of lower-of-cost-or-market accounting or write-downs of individual assets. The following table summarizes the fair value hierarchy used to determine each adjustment and the carrying value of the related assets as of September 30, 2016 and December 31, 2015. September 30, 2016 Level 1 Level 2 Level 3 (In thousands) Collateral dependent $ — $ — $ — impaired loans — — 903 Foreclosed real estate — — 353 Mortgage servicing rights — 9,351 — $ — $ 9,351 $ 1,256 December 31, 2015 Level 1 Level 2 Level 3 (In thousands) Loans held for sale $ — $ 2,870 $ — Collateral dependent impaired loans — — 552 Foreclosed real estate — — 500 Mortgage servicing rights — 2,567 — $ — $ 5,437 $ 1,052 The Company recorded a valuation allowance $150,000 and $100,000 for foreclosed real estate during the nine months ended September 30, 2016 and 2015, respectively, based on an updated appraisal. There were no losses on sale of foreclosed real estate or changes in the valuation allowance during the three months ended September 30, 2016 and 2015. There were no liabilities measured at fair value on a non-recurring basis at September 30, 2016 and December 31, 2015. The following table shows the significant unobservable inputs used in the non-recurring fair value measurements of Level 3 assets. Foreclosed real estate and collateral dependent impaired loans are evaluated for non-recurring fair value adjustments as determined by third party appraisals without adjustment except as noted below. Valuation Unobservable Discount Measurements Fair Value Technique Inputs Applied (In thousands) September 30, 2016 Foreclosed real estate $ 353 Discounted appraisal Collateral discounts 0% Collateral dependent impaired loans 903 Discounted appraisals Collateral discounts 0% December 31, 2015 Foreclosed real estate $ 500 Discounted appraisal Collateral discounts 32% Collateral dependent impaired loans 552 Discounted appraisals Collateral discounts 0% The estimated fair values, and related carrying amounts, of the Company’s financial instruments are presented below. Certain financial instruments and all non-financial instruments are exempt from disclosure requirements. Accordingly, the aggregate fair value amounts presented herein do not represent the underlying fair value of the Company. 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, and accrued interest receivable. Financial liabilities for which the fair value approximates carrying value include mortgagors’ escrow accounts and accrued interest payable. September 30, 2016 Carrying Fair Amount Value Level 1 Level 2 Level 3 (In thousands) Financial assets: Certificates of deposit $ 3,675 $ 3,719 $ — $ 3,719 $ — Securities available for sale 70,877 70,877 — 70,877 — Loans held for sale 29,092 29,092 — 29,092 — Loans, net 327,519 330,007 — — 330,007 Derivative assets 1,480 1,480 — 1,480 — Financial liabilities: Deposits $ 356,042 $ 356,376 $ — $ 356,376 $ — FHLBB advances 36,802 36,816 — 36,816 — Derivative liabilities 201 201 — 201 — December 31, 2015 Carrying Fair Amount Value Level 1 Level 2 Level 3 (In thousands) Financial assets: Certificates of deposit $ 4,675 $ 4,711 $ — $ 4,711 $ — Securities available for sale 62,267 62,267 — 62,267 — Loans held for sale 2,870 2,931 — 2,931 — Loans, net 285,151 283,542 — — 283,542 Derivative assets 107 107 — 107 — Financial liabilities: Deposits $ 309,195 $ 309,076 $ — $ 309,076 $ — FHLBB advances 34,914 34,971 — 34,971 —

Recent Accounting Pronounceme20

Recent Accounting Pronouncements (Policies)	9 Months Ended
	Sep. 30, 2016
Accounting Changes And Error Corrections [Abstract]
Recent Accounting Pronouncements	In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-02, Leases In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses

Acquisition (Tables)

Acquisition (Tables)	9 Months Ended
	Sep. 30, 2016
Business Combinations [Abstract]
Summary of Cash Consideration Paid, and Fair Values of Assets Acquired and Liabilities Assumed	The results of First Eastern’s operations are included in the Company’s consolidated statement of operations from the date of acquisition. First Eastern’s assets and liabilities were recorded at their fair value as of the date of acquisition based on management’s preliminary estimates using currently available information. Prior to the end of the one year measurement period for finalizing the purchase price allocation, if information becomes available which would indicate adjustments are required, such adjustments will be included in the purchase price allocation in the reporting period in which the adjustment amounts are determined. Cash consideration paid, and fair values of First Eastern’s assets acquired and liabilities assumed, along with the resulting bargain purchase gain, are summarized in the following table (in thousands): Fair Value As Acquired Adjustments As Recorded (In thousands) Cash and cash equivalents $ 2,951 $ — $ 2,951 Loans held for sale 26,209 450 (a) 26,659 Loans 30,824 482 (b) 31,306 Mortgage servicing rights 4,396 1,820 (c) 6,216 Premises and equipment 1,566 1,534 (d) 3,100 Core deposit intangible — 118 (e) 118 Goodwill 789 (789 ) (f) - Other assets 2,046 (55 ) (g) 1,991 Deposits (41,737 ) (53 ) (h) (41,790 ) Federal Home Loan Bank advances (13,128 ) (60 ) (h) (13,188 ) Other liabilities (1,917 ) (88 ) (i) (2,005 ) Total identifiable net assets $ 11,999 $ 3,359 15,358 Cash consideration paid to seller 13,907 Bargain purchase gain $ 1,451
Summary of Unaudited Pro Forma Financial Information	Unaudited pro forma financial information for the nine months ended September 30, 2016 and 2015 is as follows (in thousands): 2016 2015 Net Interest Income $ 10,054 $ 10,002 Non-interest Income 14,652 11,212 Net Income (Loss) 422 (243 )

Accumulated Other Comprehensi22

Accumulated Other Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Components of Accumulated Other Comprehensive Income and Related Tax Effects	The components of accumulated other comprehensive income, included in total stockholders’ equity, are as follows: September 30, December 31, 2016 2015 (In thousands) Securities available for sale: Net unrealized gain $ 1,516 $ 886 Tax effect (423 ) (423 ) Net-of-tax amount 1,093 463 Supplemental retirement plan Unrecognized net actuarial loss (718 ) (743 ) Unrecognized net prior service credit 581 598 (137 ) (145 ) Tax effect (57 ) (57 ) Net-of-tax amount (194 ) (202 ) Accumulated other comprehensive income $ 899 $ 261

Securities Available for Sale (

Securities Available for Sale (Tables)	9 Months Ended
	Sep. 30, 2016
Investments Debt And Equity Securities [Abstract]
Schedule of amortized cost and fair value of securities	The amortized cost and fair value of securities available for sale, including gross unrealized gains and losses, are as follows: Gross Gross Amortized Unrealized Unrealized Fair Cost Gains Losses Value (In thousands) September 30, 2016 Debt securities: U.S. Government-sponsored enterprises $ 3,999 $ 140 $ — $ 4,139 Corporate 3,054 91 (4 ) 3,141 Municipal 13,870 516 (2 ) 14,384 Residential mortgage-backed securities: U.S. Government-sponsored enterprises 29,769 512 (5 ) 30,276 U.S. Government-guaranteed 11,481 173 — 11,654 Commercial mortgage-backed securities: U.S. Government-guaranteed 6,643 88 — 6,731 Total debt securities 68,816 1,520 (11 ) 70,325 Mutual fund 545 7 — 552 Total securities available for sale $ 69,361 $ 1,527 $ (11 ) $ 70,877 December 31, 2015 Debt securities: U.S. Government-sponsored enterprises $ 6,886 $ 159 $ (12 ) $ 7,033 Corporate 4,250 78 (48 ) 4,280 Municipal 15,327 472 (24 ) 15,775 Residential mortgage-backed securities: U.S. Government-sponsored enterprises 19,742 406 (120 ) 20,028 U.S. Government-guaranteed 7,276 50 — 7,326 Commercial mortgage-backed securities: U.S. Government-guaranteed 7,355 33 (108 ) 7,280 Total debt securities 60,836 1,198 (312 ) 61,722 Mutual fund 545 — — 545 Total securities available for sale $ 61,381 $ 1,198 $ (312 ) $ 62,267
Investments Classified by Contractual Maturity Date	The amortized cost and fair value of debt securities by contractual maturity at September 30, 2016 are presented below. Expected maturities will differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties. Amortized Fair Cost Value (In thousands) Within 1 year $ — $ — After 1 year through 5 years 13,931 14,349 After 5 years through 10 years 6,992 7,315 20,923 21,664 Mortgage-backed securities 47,893 48,661 $ 68,816 $ 70,325
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	Information pertaining to securities with gross unrealized losses, aggregated by investment category and length of time that individual securities have been in a continuous loss position, follows: Less Over Twelve Months Gross Gross Unrealized Fair Unrealized Fair Losses Value Losses Value September 30, 2016 (In thousands) Debt securities: Corporate $ — $ — $ (4 ) $ 1,004 Municipal — — (2 ) 486 Residential mortgage-backed securities: U.S. Government-sponsored (5 ) 5,243 — — Commercial mortgage-backed securities: U.S. Government-guaranteed — — — — Total debt securities $ (5 ) $ 5,243 $ (6 ) $ 1,490 December 31, 2015 Debt securities: U.S. Government-sponsored enterprises $ — $ — $ (12 ) $ 1,989 Corporate — — (48 ) 2,088 Municipal — — (24 ) 2,185 Residential mortgage-backed securities: U.S. Government-sponsored — — (120 ) 5,994 Commercial mortgage-backed securities: U.S. Government-guaranteed — — (108 ) 5,062 Total debt securities $ — $ — $ (312 ) $ 17,318

Loans and Allowance for Loan 24

Loans and Allowance for Loan Losses (Tables)	9 Months Ended
	Sep. 30, 2016
Receivables [Abstract]
Summary of Loan Portfolio	A summary of loan portfolio is as follows: September 30, 2016 December 31, 2015 (In thousands) Mortgage loans on real estate: Residential: One-to-four family $ 179,645 $ 166,483 Home equity loans and lines of credit 34,779 33,259 Commercial 87,332 74,911 Construction 22,913 7,807 324,669 282,460 Commercial and industrial 1,929 2,040 Consumer 2,812 2,602 Total loans 329,410 287,102 Allowance for loan losses (3,096 ) (3,239 ) Net deferred loan costs and fees, and purchase premiums 1,205 1,288 $ 327,519 $ 285,151
Summary of Changes in the Allowance for Loan Losses by Portfolio Segment	The following table summarizes the changes in the allowance for loan losses by portfolio segment for the three and nine months ended September 30, 2016 and 2015: Second Residential Mortgages Commercial Commercial 1-4 Family and Real Estate Construction and Industrial Consumer Total (In thousands) Three Months Ended September 30, 2016 Allowance at June 30, 2016 $ 1,046 $ 444 $ 1,520 $ 135 $ 36 $ 78 $ 3,259 Provision (credit) for loan losses 12 (15 ) (166 ) 9 3 (3 ) (160 ) Loans charged-off — — — — — (6 ) (6 ) Recoveries 2 — — — — 1 3 Balance at September 30, 2016 $ 1,060 $ 429 $ 1,354 $ 144 $ 39 $ 70 $ 3,096 Three Months Ended September 30, 2015 Allowance at June 30, 2015 $ 1,314 $ 542 $ 1,580 $ 128 $ 44 $ 45 $ 3,653 Provision (credit) for loan losses (21 ) (35 ) (103 ) (44 ) 28 22 (153 ) Loans charged-off (8 ) — — — (37 ) (3 ) (48 ) Recoveries 2 — — — 1 2 5 Balance at September 30, 2015 $ 1,287 $ 507 $ 1,477 $ 84 $ 36 $ 66 $ 3,457 Nine Months Ended September 30, 2016 Allowance at December 31, 2015 $ 1,076 $ 512 $ 1,402 $ 159 $ 37 $ 53 $ 3,239 Provision (credit) for loan losses (20 ) (83 ) (48 ) (15 ) 2 66 (98 ) Loans charged-off — — — — — (66 ) (66 ) Recoveries 4 — — — — 17 21 Balance at September 30, 2016 $ 1,060 $ 429 $ 1,354 $ 144 $ 39 $ 70 $ 3,096 Nine Months Ended September 30, 2015 Allowance at December 31, 2014 $ 1,368 $ 488 $ 1,539 $ 60 $ 51 $ 38 $ 3,544 Provision (credit) for loan losses (76 ) 19 (62 ) 24 20 47 (28 ) Loans charged-off (8 ) — — — (37 ) (32 ) (77 ) Recoveries 3 — — — 2 13 18 Balance at September 30, 2015 $ 1,287 $ 507 $ 1,477 $ 84 $ 36 $ 66 $ 3,457
Summary of Additional Information Pertaining to the Allowance for Loan Losses	Additional information pertaining to the allowance for loan losses at September 30, 2016 and December 31, 2015 is as follows: Second Residential Mortgages Commercial Commercial 1-4 Family and Real Estate Construction and Industrial Consumer Total September 30, 2016 (In thousands) Allowance for impaired loans $ 201 $ 4 $ 12 $ — $ — $ — $ 217 Allowance for non-impaired loans 859 425 1,342 144 39 70 2,879 Total allowance for loan losses $ 1,060 $ 429 $ 1,354 $ 144 $ 39 $ 70 $ 3,096 Impaired loans $ 5,605 $ 277 $ 956 $ — $ — $ — $ 6,838 Non-impaired loans 174,040 34,502 86,376 22,913 1,929 2,812 322,572 Total loans $ 179,645 $ 34,779 $ 87,332 $ 22,913 $ 1,929 $ 2,812 $ 329,410 December 31, 2015 Allowance for impaired loans $ 254 $ 2 $ 28 $ — $ — $ — $ 284 Allowance for non-impaired loans 822 510 1,374 159 37 53 2,955 Total allowance for loan losses $ 1,076 $ 512 $ 1,402 $ 159 $ 37 $ 53 $ 3,239 Impaired loans $ 4,961 $ 277 $ 1,449 $ — $ 16 $ — $ 6,703 Non-impaired loans 161,522 32,982 73,462 7,807 2,024 2,602 280,399 Total loans $ 166,483 $ 33,259 $ 74,911 $ 7,807 $ 2,040 $ 2,602 $ 287,102
Schedule of Past Due and Non-Accrual Loans	The following is a summary of past due and non-accrual loans at September 30, 2016 and December 31, 2015: 30 - 59 Days Past Due 60 - 89 Days Past Due 90 Days or More Past Due Total Past Due Non-accrual Loans (In thousands) September 30, 2016 Residential one-to-four family $ 710 $ 419 $ — $ 1,129 $ 2,100 Home equity loans and lines of credit — 3 — 3 276 Commercial real estate — — — — — Construction — — — — — Commercial and industrial — — — — — Consumer — — — — — Total $ 710 $ 422 $ — $ 1,132 $ 2,376 December 31, 2015 Residential one-to-four family $ 403 $ 133 $ 46 $ 582 $ 2,022 Home equity loans and lines of credit — 247 — 247 30 Commercial real estate — — — — — Construction — — — — — Commercial and industrial — — — — 16 Consumer — — — — — Total $ 403 $ 380 $ 46 $ 829 $ 2,068
Summary of Impaired Loans and Additional Information Pertaining to Impaired Loans	The following is a summary of impaired loans at September 30, 2016 and December 31, 2015: Recorded Investment Unpaid Principal Balance Related Allowance (In thousands) September 30, 2016 Impaired loans without a valuation allowance: Residential one-to-four family $ 2,022 $ 2,022 $ — Home equity loans and lines of credit 247 247 — Commercial real estate 361 361 — Total 2,630 2,630 — Impaired loans with a valuation allowance: Residential one-to-four family 3,583 3,583 201 Home equity loans and lines of credit 30 30 4 Commercial real estate 595 595 12 Total 4,208 4,208 217 Total impaired loans $ 6,838 $ 6,838 $ 217 December 31, 2015 Impaired loans without a valuation allowance: Residential one-to-four family $ 874 $ 874 $ — Home equity loans and lines of credit 247 247 — Commercial real estate 422 422 — Commercial and industrial 16 16 — Total 1,559 1,559 — Impaired loans with a valuation allowance: Residential one-to-four family 4,088 4,088 254 Home equity loans and lines of credit 30 30 2 Commercial real estate 1,026 1,026 28 Total 5,144 5,144 284 Total impaired loans $ 6,703 $ 6,703 $ 284 Additional information pertaining to impaired loans follows: Average Interest Cash Basis Recorded Income Interest Investment Recognized Recognized (In thousands) Nine Months Ended September 30, 2016 Residential one-to-four family $ 5,165 $ 130 $ 49 Home equity loans and lines of credit 253 1 1 Commercial real estate 1,193 42 2 Commercial and industrial 5 1 1 Total $ 6,616 $ 174 $ 53 Nine Months Ended September 30, 2015 Residential one-to-four family $ 6,359 $ 170 $ 55 Home equity loans and lines of credit 24 1 1 Commercial real estate 6,194 214 7 Commercial and industrial 17 — — Total $ 12,594 $ 385 $ 63 Three Months Ended September 30, 2016 Residential one-to-four family $ 5,613 $ 45 $ 23 Home equity loans and lines of credit 276 — — Commercial real estate 971 12 1 Total $ 6,860 $ 57 $ 24 Three Months Ended September 30, 2015 Residential one-to-four family $ 6,139 $ 60 $ 22 Home equity loans and lines of credit — — 1 Commercial real estate 4,351 31 — Commercial and industrial 16 — — Total $ 10,506 $ 91 $ 23
Summary of Company's Loans by Risk Rating	The following table presents the Company’s loans by risk rating: September 30, 2016 December 31, 2015 Commercial Real Construction Commercial and Industrial Commercial Real Construction Commercial and Industrial (In thousands) Loans rated 1 - 3A $ 87,058 $ 22,913 $ 1,929 $ 73,517 $ 7,807 $ 2,006 Loans rated 4 64 — — 1,145 — — Loans rated 5 210 — — 249 — 34 $ 87,332 $ 22,913 $ 1,929 $ 74,911 $ 7,807 $ 2,040

Loan Servicing (Tables)

Loan Servicing (Tables)	9 Months Ended
	Sep. 30, 2016
Transfers And Servicing [Abstract]
Summary of Activity Relating to Mortgage Servicing Rights	The following table summarizes the activity relating to mortgage servicing rights for the nine months ended September 30, 2016 and 2015 (in thousands): 2016 2015 Mortgage servicing rights: Balance at beginning of year $ 2,601 $ 2,445 Additions through originations 1,676 380 Additions through First Eastern acquisition 6,216 — Amortization (644 ) (274 ) Balance at end of period $ 9,849 $ 2,551 Valuation allowance: Balance at beginning of year $ 34 $ — Provision 464 — Balance at end of period $ 498 $ — Mortgage servicing rights, amortized cost $ 9,351 $ 2,551 Mortgage servicing rights, fair value $ 9,360 $ 2,842

Fair Value of Assets and Liab26

Fair Value of Assets and Liabilities (Tables)	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis	Assets and liabilities measured at fair value on a recurring basis are summarized below. There were no liabilities measured at fair value on a recurring basis at December 31, 2015. Total Level 1 Level 2 Level 3 Fair (In thousands) September 30, 2016 Assets: Securities available for sale: Debt securities $ — $ 70,325 $ — $ 70,325 Mutual fund — 552 — 552 Loans held for sale — 29,092 — 29,092 Derivative loan commitments — 1,447 — 1,447 Forward loan sale commitments — 33 — 33 Liabilities: Forward loan sale commitments — 201 — 201 December 31, 2015 Assets: Securities available for sale: Debt securities $ — $ 61,722 $ — $ 61,722 Mutual fund — 545 — 545 Derivative loan commitments — 93 — 93 Forward loan sale commitments — 14 — 14
Schedule of Assets Measured at Fair Value on a Non-Recurring Basis	The following table summarizes the fair value hierarchy used to determine each adjustment and the carrying value of the related assets as of September 30, 2016 and December 31, 2015. September 30, 2016 Level 1 Level 2 Level 3 (In thousands) Collateral dependent $ — $ — $ — impaired loans — — 903 Foreclosed real estate — — 353 Mortgage servicing rights — 9,351 — $ — $ 9,351 $ 1,256 December 31, 2015 Level 1 Level 2 Level 3 (In thousands) Loans held for sale $ — $ 2,870 $ — Collateral dependent impaired loans — — 552 Foreclosed real estate — — 500 Mortgage servicing rights — 2,567 — $ — $ 5,437 $ 1,052
Schedule of Significant Unobservable Inputs Used in Fair Value Measurements of Level 3 Assets and Liabilities	The following table shows the significant unobservable inputs used in the non-recurring fair value measurements of Level 3 assets. Valuation Unobservable Discount Measurements Fair Value Technique Inputs Applied (In thousands) September 30, 2016 Foreclosed real estate $ 353 Discounted appraisal Collateral discounts 0% Collateral dependent impaired loans 903 Discounted appraisals Collateral discounts 0% December 31, 2015 Foreclosed real estate $ 500 Discounted appraisal Collateral discounts 32% Collateral dependent impaired loans 552 Discounted appraisals Collateral discounts 0%
Summary of Carrying Values, Estimated Fair Values and Placement in Fair Value Hierarchy of Company's Financial Instruments	The estimated fair values, and related carrying amounts, of the Company’s financial instruments are presented below. Certain financial instruments and all non-financial instruments are exempt from disclosure requirements. Accordingly, the aggregate fair value amounts presented herein do not represent the underlying fair value of the Company. 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, and accrued interest receivable. Financial liabilities for which the fair value approximates carrying value include mortgagors’ escrow accounts and accrued interest payable. September 30, 2016 Carrying Fair Amount Value Level 1 Level 2 Level 3 (In thousands) Financial assets: Certificates of deposit $ 3,675 $ 3,719 $ — $ 3,719 $ — Securities available for sale 70,877 70,877 — 70,877 — Loans held for sale 29,092 29,092 — 29,092 — Loans, net 327,519 330,007 — — 330,007 Derivative assets 1,480 1,480 — 1,480 — Financial liabilities: Deposits $ 356,042 $ 356,376 $ — $ 356,376 $ — FHLBB advances 36,802 36,816 — 36,816 — Derivative liabilities 201 201 — 201 — December 31, 2015 Carrying Fair Amount Value Level 1 Level 2 Level 3 (In thousands) Financial assets: Certificates of deposit $ 4,675 $ 4,711 $ — $ 4,711 $ — Securities available for sale 62,267 62,267 — 62,267 — Loans held for sale 2,870 2,931 — 2,931 — Loans, net 285,151 283,542 — — 283,542 Derivative assets 107 107 — 107 — Financial liabilities: Deposits $ 309,195 $ 309,076 $ — $ 309,076 $ — FHLBB advances 34,914 34,971 — 34,971 —

Basis of Presentation - Additio

Basis of Presentation - Additional Information (Detail) - USD ($)	Jul. 02, 2016	Jul. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Sep. 30, 2016	Jul. 01, 2016
Basis Of Presentation [Line Items]
Sale of stock, transaction date	Jul. 1, 2016
Gross proceeds from common stock	$ 56,867,500
Sale of share in employee stock ownership plan	469,498
Loan repaid term	25 years
Stock offering costs				$ 2,367,000
Stock conversion expense			$ 2,275,000		$ 2,275,000
The Randolph Savings Charitable Foundation, Inc. [Member]
Basis Of Presentation [Line Items]
Sale of share in employee stock ownership plan					469,498
Conversion of stock, Common shares issued					181,976
Conversion of stock, cash					$ 455,000
Stock conversion expense		$ 2,274,700
Common Stock [Member]
Basis Of Presentation [Line Items]
Mutual-to-stock transaction, shares sold	5,686,750
Common Stock [Member] | Maximum [Member]
Basis Of Presentation [Line Items]
Sale of stock, price per share						$ 10

Acquisition - Additional Inform

Acquisition - Additional Information (Detail)	Jul. 03, 2016USD ($)Office	Jun. 30, 2016USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Jun. 30, 2016USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Dec. 31, 2015USD ($)
Business Acquisition [Line Items]
Business acquisition, date						Jul. 1, 2016
Reversal of special bonus paid		$ 1,600,000
Income tax expense (benefit)				$ (1,000)		$ 3,000	$ (5,000)
Pro Forma [Member]
Business Acquisition [Line Items]
Income tax expense (benefit)						0	$ 0
First Eastern Bankshares Corporation [Member]
Business Acquisition [Line Items]
Cash payment to acquisition	$ 13,900,000
Number of residential loan production office | Office	8
Proceeds from sale of mortgage loans held-for-sale in the secondary mortgage market					$ 175,200,000			$ 417,600,000
Amount included in net interest income and non-interest income			$ 537,000			4,039,000
Contribution to consolidated net income			$ 925,000			$ 925,000

Acquisition - Summary of Cash C

Acquisition - Summary of Cash Consideration Paid, and Fair Values of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands	Jul. 03, 2016	Sep. 30, 2016	Sep. 30, 2016
Business Acquisition [Line Items]
Bargain purchase gain		$ 1,451	$ 1,451
First Eastern Bankshares Corporation [Member]
Business Acquisition [Line Items]
Cash and cash equivalents	$ 2,951
Loans held for sale	26,659
Loans	31,306
Mortgage servicing rights	6,216
Premises and equipment	3,100
Core deposit intangible	118
Other assets	1,991
Deposits	(41,790)
Federal Home Loan Bank advances	(13,188)
Other liabilities	(2,005)
Total identifiable net assets	15,358
Cash consideration paid to seller	13,907
Bargain purchase gain	1,451
First Eastern Bankshares Corporation [Member] | As Acquired [Member]
Business Acquisition [Line Items]
Cash and cash equivalents	2,951
Loans held for sale	26,209
Loans	30,824
Mortgage servicing rights	4,396
Premises and equipment	1,566
Goodwill	789
Other assets	2,046
Deposits	(41,737)
Federal Home Loan Bank advances	(13,128)
Other liabilities	(1,917)
Total identifiable net assets	11,999
First Eastern Bankshares Corporation [Member] | Fair Value Adjustments [Member]
Business Acquisition [Line Items]
Loans held for sale	450
Loans	482
Mortgage servicing rights	1,820
Premises and equipment	1,534
Core deposit intangible	118
Goodwill	(789)
Other assets	(55)
Deposits	(53)
Federal Home Loan Bank advances	(60)
Other liabilities	(88)
Total identifiable net assets	$ 3,359

Acquisition - Summary of Cash30

Acquisition - Summary of Cash Consideration Paid, and Fair Values of Assets Acquired and Liabilities Assumed (Parenthetical) (Detail) $ in Millions	Jul. 03, 2016USD ($)
Business Combinations [Abstract]
Book value of mortgage servicing rights	$ 789.3
Estimated fair value percentage of core deposit relationships	1.10%

Acquisition - Summary of Unaudi

Acquisition - Summary of Unaudited Pro Forma Financial Information (Detail) - First Eastern Bankshares Corporation [Member] - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Business Acquisition [Line Items]
Net Interest Income	$ 10,054	$ 10,002
Non-interest Income	14,652	11,212
Net Income (Loss)	$ 422	$ (243)

Accumulated Other Comprehensi32

Accumulated Other Comprehensive Income - Components of Accumulated Other Comprehensive Income and Related Tax Effects (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income, Net of Tax	$ (354)	$ 898	$ 638	$ 802
Accumulated other comprehensive income	$ 899		899		$ 261
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income, Before tax			1,516		886
Other comprehensive income, Tax effect			(423)		(423)
Other comprehensive income, Net of Tax			1,093		463
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income, Before tax			(718)		(743)
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income, Before tax			581		598
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income, Before tax			(137)		(145)
Other comprehensive income, Tax effect			(57)		(57)
Other comprehensive income, Net of Tax			$ (194)		$ (202)

Securities Available for Sale -

Securities Available for Sale - Schedule of Amortized Cost and Fair Value of Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 69,361	$ 61,381
Gross Unrealized Gains	1,527	1,198
Gross Unrealized Losses	(11)	(312)
Fair Value	70,877	62,267
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	68,816	60,836
Gross Unrealized Gains	1,520	1,198
Gross Unrealized Losses	(11)	(312)
Fair Value	70,325	61,722
Debt Securities [Member] | US Government-sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,999	6,886
Gross Unrealized Gains	140	159
Gross Unrealized Losses		(12)
Fair Value	4,139	7,033
Debt Securities [Member] | Corporate [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,054	4,250
Gross Unrealized Gains	91	78
Gross Unrealized Losses	(4)	(48)
Fair Value	3,141	4,280
Debt Securities [Member] | Municipal [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	13,870	15,327
Gross Unrealized Gains	516	472
Gross Unrealized Losses	(2)	(24)
Fair Value	14,384	15,775
Debt Securities [Member] | Residential Mortgage-backed Securities, US Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	29,769	19,742
Gross Unrealized Gains	512	406
Gross Unrealized Losses	(5)	(120)
Fair Value	30,276	20,028
Debt Securities [Member] | Residential Mortgage-backed Securities, US Government Guaranteed [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	11,481	7,276
Gross Unrealized Gains	173	50
Fair Value	11,654	7,326
Debt Securities [Member] | Commercial Mortgage Backed Securities, U.S. Government-guaranteed [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	6,643	7,355
Gross Unrealized Gains	88	33
Gross Unrealized Losses		(108)
Fair Value	6,731	7,280
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	545	545
Gross Unrealized Gains	7
Fair Value	$ 552	$ 545

Securities Available for Sale34

Securities Available for Sale - Investments Classified by Contractual Maturity Date (Detail) $ in Thousands	Sep. 30, 2016USD ($)
Available-for-sale Securities, Debt Maturities, Amortized Cost
After 1 year through 5 years	$ 13,931
After 5 years through 10 years	6,992
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis, Total	20,923
Mortgage-backed securities	47,893
Available-for-sale Debt Securities, Amortized Cost Basis, Total	68,816
Available-for-sale Securities, Debt Maturities, Fair Value
After 1 year through 5 years	14,349
After 5 years through 10 years	7,315
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Fair Value Total	21,664
Mortgage-backed securities	48,661
Available-for-sale Securities, Debt Securities, Fair Value Total	$ 70,325

Securities Available for Sale35

Securities Available for Sale - Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value (Detail) - Debt Securities [Member] - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Less Than Twelve Months, Gross Unrealized Losses	$ (5)
Less Than Twelve Months, Fair Value	5,243
Over Twelve Months, Gross Unrealized Losses	(6)	$ (312)
Over Twelve Months, Fair Value	1,490	17,318
Corporate [Member]
Schedule of Available-for-sale Securities [Line Items]
Over Twelve Months, Gross Unrealized Losses	(4)	(48)
Over Twelve Months, Fair Value	1,004	2,088
Municipal [Member]
Schedule of Available-for-sale Securities [Line Items]
Over Twelve Months, Gross Unrealized Losses	(2)	(24)
Over Twelve Months, Fair Value	486	2,185
Residential Mortgage-backed Securities, US Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than Twelve Months, Gross Unrealized Losses	(5)
Less Than Twelve Months, Fair Value	$ 5,243
Over Twelve Months, Gross Unrealized Losses		(120)
Over Twelve Months, Fair Value		5,994
Commercial Mortgage Backed Securities, U.S. Government-guaranteed [Member]
Schedule of Available-for-sale Securities [Line Items]
Over Twelve Months, Gross Unrealized Losses		(108)
Over Twelve Months, Fair Value		5,062
US Government-sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Over Twelve Months, Gross Unrealized Losses		(12)
Over Twelve Months, Fair Value		$ 1,989

Securities Available for Sale36

Securities Available for Sale - Additional Information (Detail)	Sep. 30, 2016Debt_Security
Schedule of Available-for-sale Securities [Line Items]
Number of debt securities with unrealized losses	4
Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses debt securities aggregate depreciation percentage	1.00%

Loans and Allowance for Loan 37

Loans and Allowance for Loan Losses - Summary of Loan Portfolio (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 329,410	$ 287,102
Allowance for loan losses	(3,096)	(3,239)
Net deferred loan costs and fees, and purchase premiums	1,205	1,288
Net loans	327,519	285,151
Real Estate Sector [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	324,669	282,460
Commercial Real Estate Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	87,332	74,911
Commercial Real Estate Loans [Member] | Real Estate Sector [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	87,332	74,911
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,929	2,040
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	2,812	2,602
One-to-Four Family [Member] | Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	179,645	166,483
One-to-Four Family [Member] | Residential Real Estate [Member] | Real Estate Sector [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	179,645	166,483
Home Equity Loans and Lines of Credit [Member] | Residential Real Estate [Member] | Real Estate Sector [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	34,779	33,259
Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	22,913	7,807
Construction [Member] | Real Estate Sector [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 22,913	$ 7,807

Loans and Allowance for Loan 38

Loans and Allowance for Loan Losses - Summary of Changes in the Allowance for Loan Losses by Portfolio Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 3,259	$ 3,653	$ 3,239	$ 3,544
Provision (credit) for loan losses	(160)	(153)	(98)	(28)
Loans charged-off	(6)	(48)	(66)	(77)
Recoveries	3	5	21	18
Ending balance	3,096	3,457	3,096	3,457
Commercial Real Estate Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	1,520	1,580	1,402	1,539
Provision (credit) for loan losses	(166)	(103)	(48)	(62)
Ending balance	1,354	1,477	1,354	1,477
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	36	44	37	51
Provision (credit) for loan losses	3	28	2	20
Loans charged-off		(37)		(37)
Recoveries		1		2
Ending balance	39	36	39	36
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	78	45	53	38
Provision (credit) for loan losses	(3)	22	66	47
Loans charged-off	(6)	(3)	(66)	(32)
Recoveries	1	2	17	13
Ending balance	70	66	70	66
One-to-Four Family [Member] | Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	1,046	1,314	1,076	1,368
Provision (credit) for loan losses	12	(21)	(20)	(76)
Loans charged-off		(8)		(8)
Recoveries	2	2	4	3
Ending balance	1,060	1,287	1,060	1,287
Second Mortgages and HELOC [Member] | Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	444	542	512	488
Provision (credit) for loan losses	(15)	(35)	(83)	19
Ending balance	429	507	429	507
Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	135	128	159	60
Provision (credit) for loan losses	9	(44)	(15)	24
Ending balance	$ 144	$ 84	$ 144	$ 84

Loans and Allowance for Loan 39

Loans and Allowance for Loan Losses - Summary of Additional Information Pertaining to the Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for impaired loans	$ 217		$ 284
Allowance for non-impaired loans	2,879		2,955
Total allowance for loan losses	3,096	$ 3,259	3,239	$ 3,457	$ 3,653	$ 3,544
Impaired loans	6,838		6,703
Non-impaired loans	322,572		280,399
Total loans	329,410		287,102
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for non-impaired loans	39		37
Total allowance for loan losses	39	36	37	36	44	51
Impaired loans			16
Non-impaired loans	1,929		2,024
Total loans	1,929		2,040
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for non-impaired loans	70		53
Total allowance for loan losses	70	78	53	66	45	38
Non-impaired loans	2,812		2,602
Total loans	2,812		2,602
One-to-Four Family [Member] | Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for impaired loans	201		254
Allowance for non-impaired loans	859		822
Total allowance for loan losses	1,060	1,046	1,076	1,287	1,314	1,368
Impaired loans	5,605		4,961
Non-impaired loans	174,040		161,522
Total loans	179,645		166,483
Second Mortgages and HELOC [Member] | Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for impaired loans	4		2
Allowance for non-impaired loans	425		510
Total allowance for loan losses	429	444	512	507	542	488
Impaired loans	277		277
Non-impaired loans	34,502		32,982
Total loans	34,779		33,259
Commercial Real Estate Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for impaired loans	12		28
Allowance for non-impaired loans	1,342		1,374
Total allowance for loan losses	1,354		1,402
Impaired loans	956		1,449
Non-impaired loans	86,376		73,462
Total loans	87,332		74,911
Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for non-impaired loans	144		159
Total allowance for loan losses	144	$ 135	159	$ 84	$ 128	$ 60
Non-impaired loans	22,913		7,807
Total loans	$ 22,913		$ 7,807

Loans and Allowance for Loan 40

Loans and Allowance for Loan Losses - Schedule of Past Due and Non-Accrual Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 1,132	$ 829
Non-accrual Loans	2,376	2,068
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual Loans		16
30 - 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	710	403
60 - 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	422	380
90 Days or More Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		46
One-to-Four Family [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,129	582
Non-accrual Loans	2,100	2,022
One-to-Four Family [Member] | 30 - 59 Days Past Due [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	710	403
One-to-Four Family [Member] | 60 - 89 Days Past Due [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	419	133
One-to-Four Family [Member] | 90 Days or More Past Due [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		46
Home Equity Loans and Lines of Credit [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3	247
Non-accrual Loans	276	30
Home Equity Loans and Lines of Credit [Member] | 60 - 89 Days Past Due [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 3	$ 247

Loans and Allowance for Loan 41

Loans and Allowance for Loan Losses - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2016USD ($)TDRLoan	Sep. 30, 2015USD ($)TDRLoan	Dec. 31, 2015USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans past due 90 days or more	$ 0		$ 0		$ 0
Impaired loans, additional funds committed	0		0
Troubled debt restructuring amount			$ 6,050,000	$ 10,140,000
Number of loans modified | Loan			0	2
Aggregate balance of loans modified		$ 434,000		$ 434,000
Change to allowance for loan losses	0	0	$ 0	0
Loans and leases receivable internal loan rating delinquent maximum days			90 days
Total loans	329,410,000		$ 329,410,000		287,102,000
30 - 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructurings defaulted over 30 days past due	0	0	0	$ 0
Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest rate on modified loans, deduction range				1.00%
Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest rate on modified loans, deduction range				3.00%
Non Accrual Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructuring amount			1,714,000	$ 2,334,000
Residential Mortgages | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	897,000		897,000		378,000
Residential Mortgages | Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	1,418,000		1,418,000		2,262,000
Home Equity Loans and Lines of Credit [Member] | Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	276,000		$ 276,000		277,000
Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans subject to troubled debt restructurings | TDR			24	26
Loans subject to troubled debt restructurings, amount	5,367,000	6,113,000	$ 5,367,000	$ 6,113,000
Residential Real Estate [Member] | Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructuring, interest rate concession period			3 months
Residential Real Estate [Member] | Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructuring, interest rate concession period			30 years
Commercial Real Estate Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans subject to troubled debt restructurings | TDR			4	7
Loans subject to troubled debt restructurings, amount	683,000	$ 4,027,000	$ 683,000	$ 4,027,000
Total loans	87,332,000		87,332,000		74,911,000
Commercial Real Estate Loans [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	210,000		210,000		249,000
Commercial Real Estate Loans [Member] | Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 64,000		$ 64,000		$ 1,145,000
Commercial Real Estate Loans [Member] | Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructuring, interest rate concession period			1 year

Loans and Allowance for Loan 42

Loans and Allowance for Loan Losses - Summary of Impaired Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Financing Receivable, Impaired [Line Items]
Recorded Investment without a valuation allowance	$ 2,630	$ 1,559
Unpaid Principal Balance without a valuation allowance	2,630	1,559
Recorded Investment with a valuation allowance	4,208	5,144
Unpaid Principal Balance with a valuation allowance	4,208	5,144
Related Allowance, Total impaired loans	217	284
Recorded Investment, Total impaired loans	6,838	6,703
Unpaid Principal Balance, Total impaired loans	6,838	6,703
Commercial Real Estate Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment without a valuation allowance	361	422
Unpaid Principal Balance without a valuation allowance	361	422
Recorded Investment with a valuation allowance	595	1,026
Unpaid Principal Balance with a valuation allowance	595	1,026
Related Allowance, Total impaired loans	12	28
Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment without a valuation allowance		16
Unpaid Principal Balance without a valuation allowance		16
One-to-Four Family [Member] | Residential Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment without a valuation allowance	2,022	874
Unpaid Principal Balance without a valuation allowance	2,022	874
Recorded Investment with a valuation allowance	3,583	4,088
Unpaid Principal Balance with a valuation allowance	3,583	4,088
Related Allowance, Total impaired loans	201	254
Home Equity Loans and Lines of Credit [Member] | Residential Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment without a valuation allowance	247	247
Unpaid Principal Balance without a valuation allowance	247	247
Recorded Investment with a valuation allowance	30	30
Unpaid Principal Balance with a valuation allowance	30	30
Related Allowance, Total impaired loans	$ 4	$ 2

Loans and Allowance for Loan 43

Loans and Allowance for Loan Losses - Summary of Additional Information Pertaining to Impaired Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	$ 6,860	$ 10,506	$ 6,616	$ 12,594
Interest Income Recognized	57	91	174	385
Cash Basis Interest Recognized	24	23	53	63
Residential Real Estate [Member] | One-to-Four Family [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	5,613	6,139	5,165	6,359
Interest Income Recognized	45	60	130	170
Cash Basis Interest Recognized	23	22	49	55
Residential Real Estate [Member] | Home Equity Loans and Lines of Credit [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	276		253	24
Interest Income Recognized			1	1
Cash Basis Interest Recognized		1	1	1
Commercial Real Estate Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	971	4,351	1,193	6,194
Interest Income Recognized	12	31	42	214
Cash Basis Interest Recognized	$ 1		2	7
Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment		$ 16	5	$ 17
Interest Income Recognized			1
Cash Basis Interest Recognized			$ 1

Loans and Allowance for Loan 44

Loans and Allowance for Loan Losses - Summary of Company's Loans by Risk Rating (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$ 329,410	$ 287,102
Commercial Real Estate Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	87,332	74,911
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	1,929	2,040
Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	22,913	7,807
Pass [Member] | Commercial Real Estate Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	87,058	73,517
Pass [Member] | Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	1,929	2,006
Pass [Member] | Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	22,913	7,807
Special Mention [Member] | Commercial Real Estate Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	64	1,145
Substandard [Member] | Commercial Real Estate Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$ 210	249
Substandard [Member] | Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans		$ 34

Loan Servicing - Additional Inf

Loan Servicing - Additional Information (Detail) - USD ($)	Jul. 03, 2016	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Servicing Assets At Amortized Value [Line Items]
Unpaid principal balance of residential mortgage loans serviced for others		$ 1,200,000,000	$ 317,200,000
Mortgage servicing rights		9,351,000	$ 2,567,000
Estimated fair value of mortgage servicing rights		$ 9,360,000		$ 2,842,000
First Eastern [Member]
Servicing Assets At Amortized Value [Line Items]
Discount rate	10.00%	12.00%
Increased in valuation allowance of mortgage servicing rights		$ 416,000
First Eastern [Member] | Residential Mortgage Loans [Member]
Servicing Assets At Amortized Value [Line Items]
Mortgage servicing rights	$ 789,300,000
Estimated fair value of mortgage servicing rights	$ 6,200,000
Minimum [Member] | First Eastern [Member]
Servicing Assets At Amortized Value [Line Items]
Projected annual prepayment speed	6.00%
Maximum [Member] | First Eastern [Member]
Servicing Assets At Amortized Value [Line Items]
Projected annual prepayment speed	28.00%

Loan Servicing - Summary of Act

Loan Servicing - Summary of Activity Relating to Mortgage Servicing Rights (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Mortgage servicing rights:
Balance at beginning of year	$ 2,601	$ 2,445
Additions through originations	1,676	380
Amortization	(644)	(274)
Balance at end of period	9,849	2,551
Valuation allowance:
Balance at beginning of year	34
Provision	464
Balance at end of period	498
Mortgage servicing rights, amortized cost	9,351	2,551
Mortgage servicing rights, fair value	9,360	$ 2,842
First Eastern [Member]
Mortgage servicing rights:
Additions through originations	$ 6,216

On-Balance Sheet Derivative I47

On-Balance Sheet Derivative Instruments and Hedging Activities - Additional Information (Detail) - USD ($)	Sep. 30, 2016	Dec. 31, 2015
Derivative Loan Commitments [Member]
Derivative [Line Items]
Derivative, Notional amount	$ 83,310,000	$ 5,292,000
Forward Loan Sale Commitments [Member]
Derivative [Line Items]
Derivative, Notional amount	91,180,000	7,371,000
Forward Loan Sale Commitments [Member] | Mandatory Delivery Contracts [Member]
Derivative [Line Items]
Derivative, Notional amount	60,085,000
Other Assets [Member] | Derivative Loan Commitments [Member]
Derivative [Line Items]
Derivative fair value, Asset	1,447,000	93,000
Other Assets [Member] | Forward Loan Sale Commitments [Member]
Derivative [Line Items]
Derivative fair value, Asset	33,000	$ 14,000
Other Liabilities [Member] | Forward Loan Sale Commitments [Member]
Derivative [Line Items]
Derivative fair value, Liability	$ 201,000

Employee Stock Ownership Plan -

Employee Stock Ownership Plan - Additional Information (Detail) - USD ($)	Jul. 02, 2016	Sep. 30, 2016
Employee Stock Ownership Plan E S O P Disclosures [Line Items]
Sale of share in employee stock ownership plan	469,498
Number of allocated shares		18,780
Annual allocation of shares, expiration year		2,040
Shares committed to be released		9,390
Fair value of shares under employee stock ownership plan		$ 120,200
Unallocated shares		460,108
Unallocated shares, value		$ 6,271,300
The Randolph Savings Charitable Foundation, Inc. [Member]
Employee Stock Ownership Plan E S O P Disclosures [Line Items]
Sale of share in employee stock ownership plan		469,498
Percentage of stock issued during period shares employee stock ownership plan		8.00%

Earning Per Share - Additional

Earning Per Share - Additional Information (Detail) - shares	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Potentially dilutive common stock equivalents outstanding		0
Common stock, shares outstanding	5,868,726	5,868,726	0
Weighted Average Number of Shares, Unallocated ESOP shares	464,803
Weighted average common shares outstanding (basic and diluted)	5,403,923

Fair Value of Assets and Liab50

Fair Value of Assets and Liabilities - Additional information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net gain on sales of mortgage loans	$ 5,401,000	$ 755,000	$ 7,140,000	$ 1,945,000
Liabilities measured at fair value on recurring basis					$ 0
Valuation allowance for foreclosed real estate	0	$ 0	150,000	$ 100,000
Liabilities measured at fair value on nonrecurring basis	0		0		$ 0
Residential Mortgage Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate fair value of loans held for sale	29,100,000		29,100,000
Contractual balance of loans held for sale	28,200,000		$ 28,200,000
Net gain on sales of mortgage loans	$ 911,000

Fair Value of Assets and Liab51

Fair Value of Assets and Liabilities - Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value	$ 70,877	$ 62,267
Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value	70,325	61,722
Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value	552	545
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value	70,877	62,267
Fair value, Loans held for sale	29,092	2,931
Derivative assets	1,480	107
Derivative fair value, Liability	201
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, Loans held for sale	29,092
Derivative fair value, Liability	201
Fair Value, Measurements, Recurring [Member] | Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value	70,325	61,722
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value	552	545
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, Loans held for sale	29,092
Derivative fair value, Liability	201
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value	70,325	61,722
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value	552	545
Fair Value, Measurements, Recurring [Member] | Derivative Loan Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	1,447	93
Fair Value, Measurements, Recurring [Member] | Derivative Loan Commitments [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	1,447	93
Fair Value, Measurements, Recurring [Member] | Forward Loan Sale Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	33	14
Fair Value, Measurements, Recurring [Member] | Forward Loan Sale Commitments [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	$ 33	$ 14

Fair Value of Assets and Liab52

Fair Value of Assets and Liabilities - Schedule of Assets Measured at Fair Value on a Non-Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage servicing rights, fair value	$ 9,360		$ 2,842
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, Loans held for sale	29,092	$ 2,931
Fair Value, Measurements, Nonrecurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage servicing rights, fair value	9,351	2,567
Assets, Fair Value Disclosure	9,351	5,437
Fair value, Loans held for sale		2,870
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, Collateral dependent impaired loans	903	552
Fair value, Foreclosed real estate	353	500
Assets, Fair Value Disclosure	$ 1,256	$ 1,052

Fair Value of Assets and Liab53

Fair Value of Assets and Liabilities - Schedule of Significant Unobservable Inputs Used in Fair Value Measurements of Level 3 Assets and Liabilities (Detail) - Fair Value, Measurements, Nonrecurring [Member] - Level 3 [Member] - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Fair Value	$ 1,256	$ 1,052
Foreclosed Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Fair Value	$ 353	$ 500
Collateral discounts	0.00%	32.00%
Collateral Dependent Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Fair Value	$ 903	$ 552
Collateral discounts	0.00%	0.00%

Fair Value of Assets and Liab54

Fair Value of Assets and Liabilities - Schedule of Significant Unobservable Inputs Used in Fair Value Measurements of Level 3 Assets and Liabilities (Parenthetical) (Detail) - Fair Value, Measurements, Nonrecurring [Member] - Level 3 [Member]	9 Months Ended
	Sep. 30, 2016
Foreclosed Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Valuation technique	Discounted appraisal
Collateral Dependent Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Valuation technique	Discounted appraisals

Fair Value of Assets and Liab55

Fair Value of Assets and Liabilities - Summary of Carrying Values, Estimated Fair Values and Placement in Fair Value Hierarchy of Company's Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Financial assets:
Securities available for sale	$ 70,877	$ 62,267
Level 2 [Member]
Financial assets:
Certificates of deposit	3,719	4,711
Securities available for sale	70,877	62,267
Loans held for sale	29,092	2,931
Derivative assets	1,480	107
Financial liabilities:
Deposits	356,376	309,076
FHLBB advances	36,816	34,971
Derivative liabilities	201
Level 3 [Member]
Financial assets:
Loans, net	330,007	283,542
Carrying Amount [Member]
Financial assets:
Certificates of deposit	3,675	4,675
Securities available for sale	70,877	62,267
Loans held for sale	29,092	2,870
Loans, net	327,519	285,151
Derivative assets	1,480	107
Financial liabilities:
Deposits	356,042	309,195
FHLBB advances	36,802	34,914
Derivative liabilities	201
Fair Value [Member]
Financial assets:
Certificates of deposit	3,719	4,711
Securities available for sale	70,877	62,267
Loans held for sale	29,092	2,931
Loans, net	330,007	283,542
Derivative assets	1,480	107
Financial liabilities:
Deposits	356,376	309,076
FHLBB advances	36,816	$ 34,971
Derivative liabilities	$ 201