Randolph Bancorp (RNDB) 10-K 14 Mar 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 28, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	RNDB
Entity Registrant Name	Randolph Bancorp, Inc.
Entity Central Index Key	0001667161
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Public Float			$ 83,029,900
Entity Common Stock, Shares Outstanding		5,898,793

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets
Cash and due from banks	$ 3,451	$ 3,562
Interest-bearing deposits	3,667	5,260
Total cash and cash equivalents	7,118	8,822
Certificates of deposit	2,205	2,940
Securities available for sale, at fair value	50,556	61,576
Loans held for sale, at fair value	38,474	25,390
Loans, net of allowance for loan losses of $4,437 in 2018 and $3,737 in 2017	483,846	400,373
Federal Home Loan Bank of Boston stock, at cost	4,700	3,310
Accrued interest receivable	1,504	1,432
Mortgage servicing rights, net	7,786	6,397
Premises and equipment, net	6,368	8,670
Bank-owned life insurance	8,256	8,037
Foreclosed real estate, net	65	193
Other assets	3,462	4,752
Total assets	614,340	531,892
Deposits:
Noninterest-bearing	64,229	62,130
Interest bearing	312,321	297,690
Brokered	60,580	7,016
Total deposits	437,130	366,836
Federal Home Loan Bank of Boston advances	89,036	75,954
Mortgagors' escrow accounts	2,129	907
Post-employment benefit obligations	2,551	2,750
Other liabilities	5,533	3,962
Total liabilities	536,379	450,409
Commitments and contingencies (Note 16)
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: 5,903,793 shares at December 31, 2018 and 6,034,276 shares at December 31, 2017	60	61
Additional paid-in capital	55,608	56,493
Retained earnings	28,329	30,415
ESOP-Unearned compensation	(4,132)	(4,319)
Accumulated other comprehensive loss, net of tax	(1,904)	(1,167)
Total stockholders' equity	77,961	81,483
Total liabilities and stockholders' equity	$ 614,340	$ 531,892

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Loans, allowance for loan losses	$ 4,437	$ 3,737
Preferred stock, par value	$ 0	$ 0
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	5,903,793	6,034,276
Common stock, shares outstanding	5,903,793	6,034,276

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Interest and dividend income:
Loans	$ 19,541,000	$ 15,099,000
Securities-taxable	1,318,000	1,259,000
Securities-tax exempt	120,000	347,000
Interest-bearing deposits and certificates of deposit	305,000	235,000
Total interest and dividend income	21,284,000	16,940,000
Interest expense:
Deposits	3,070,000	1,556,000
Federal Home Loan Bank of Boston advances	1,518,000	554,000
Total interest expense	4,588,000	2,110,000
Net interest income	16,696,000	14,830,000
Provision for loan losses	762,000	540,000
Net interest income after provision for loan losses	15,934,000	14,290,000
Non-interest income:
Customer service fees	1,464,000	1,455,000
Gain on loan origination and sale activities, net	7,539,000	9,151,000
Mortgage servicing fees, net	1,264,000	1,473,000
Gain (loss) on sales/calls of securities and impairment write-down, net	(11,000)
Increase in cash surrender value of life insurance	218,000	153,000
Gain on sales of buildings	2,476,000
Other	733,000	731,000
Total non-interest income	13,683,000	12,963,000
Non-interest expenses:
Salaries and employee benefits	19,765,000	18,731,000
Occupancy and equipment	2,873,000	2,655,000
Data processing	692,000	758,000
Professional fees	1,164,000	1,344,000
Marketing	1,141,000	989,000
Foreclosed real estate, net	40,000
FDIC deposit insurance	175,000	145,000
Restructuring charges	968,000	594,000
Merger and integration costs		531,000
Other	4,854,000	4,075,000
Total non-interest expenses	31,672,000	29,822,000
Loss before income taxes	(2,055,000)	(2,569,000)
Income tax expense (benefit)	31,000	(443,000)
Net income (loss)	$ (2,086,000)	$ (2,126,000)
Weighted average common shares outstanding (basic and diluted)	5,570,720	5,468,514
Loss per common share (basic and diluted)	$ (0.37)	$ (0.39)

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Net loss		$ (2,086)	$ (2,126)
Securities available for sale:
Unrealized holding gains (losses)		(721)	74
Reclassification adjustment for net (gains) losses and impairment write-down realized in income	[1]	11
Net unrealized gain (loss)		(710)	74
Related tax effects			0
Net-of-tax amount		(710)	74
Related tax effects			0
Net-of-tax amount		(27)	(77)
Total other comprehensive loss		(737)	(3)
Comprehensive loss		(2,823)	(2,129)
Supplemental Retirement Plan [Member]
Securities available for sale:
Actuarial losses	[2]	41	38
Prior service credits recognized	[2]	(89)	(89)
Actuarial gains (losses) arising during the year		21	(26)
Net change in supplemental retirement plan		$ (27)	$ (77)
[1]	Amounts are included in gain (loss) on sales/calls of securities and impairment write-down, net in the consolidated statements of operations.
[2]	Amounts are included in other non-interest expenses in the consolidated statements of operations.

Consolidated Statements Changes

Consolidated Statements Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Unearned Compensation ESOP [Member]	Accumulated Other Comprehensive Loss [Member]
Beginning balance at Dec. 31, 2016	$ 83,302	$ 59	$ 56,373	$ 32,661	$ (4,507)	$ (1,284)
Beginning balance, shares at Dec. 31, 2016		5,868,726
Net loss	(2,126)			(2,126)
Other comprehensive loss	(3)					(3)
Stock repurchased	(160)		(160)
Stock repurchased, shares		(10,689)
Restricted stock awards granted		$ 2	(2)
Restricted stock awards granted, shares		192,491
Restricted stock awards forfeited, shares		(16,252)
Stock-based compensation	184		184
ESOP shares committed to be released	286		98		188
Adoption impact - ASU 2018-02				(120)		120
Ending balance at Dec. 31, 2017	81,483	$ 61	56,493	30,415	(4,319)	(1,167)
Ending balance, shares at Dec. 31, 2017		6,034,276
Net loss	(2,086)			(2,086)
Other comprehensive loss	(737)					(737)
Stock repurchased	(1,716)	$ (1)	(1,715)
Stock repurchased, shares		(109,910)
Restricted stock awards forfeited, shares		(15,710)
Share redemption for tax withholdings for restricted stock vesting	(81)		(81)
Share redemption for tax with holdings for restricted stock vesting, shares		(4,863)
Stock-based compensation	797		797
ESOP shares committed to be released	301		114		187
Ending balance at Dec. 31, 2018	$ 77,961	$ 60	$ 55,608	$ 28,329	$ (4,132)	$ (1,904)
Ending balance, shares at Dec. 31, 2018		5,903,793

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net loss	$ (2,086,000)	$ (2,126,000)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Provision for loan losses	762,000	540,000
Loans originated for sale	(393,251,000)	(398,696,000)
Net gain on sales of mortgage loans	(7,931,000)	(9,438,000)
Proceeds from sales of mortgage loans	391,149,000	413,196,000
Net amortization of securities	183,000	271,000
Net change in deferred loan costs and fees, and purchase premiums	(56,000)	(276,000)
Loss on sales/calls of securities and impairment write-down	11,000
Gain on sales of buildings	(2,476,000)
Depreciation and amortization	835,000	605,000
Impairment write-down on property and equipment	166,000	225,000
Impairment write-down on foreclosed real estate	36,000
Stock-based compensation	797,000	184,000
ESOP expense	301,000	286,000
Increase in cash surrender value of life insurance	(218,000)	(153,000)
Net (increase) decrease in mortgage servicing rights	(1,389,000)	2,089,000
Other, net	1,876,000	(797,000)
Net cash provided by (used in) operating activities	(11,291,000)	5,910,000
Redemption of certificates of deposit	735,000	735,000
Securities available for sale:
Sales	8,958,000
Calls/maturities	5,562,000	2,586,000
Purchases	(9,993,000)
Principal payments on mortgage-backed securities	5,589,000	4,278,000
Loan originations, net of principal repayments	(96,088,000)	(31,614,000)
Proceeds from sale of portfolio loans	25,038,000
Loan purchases and participations	(16,180,000)	(36,032,000)
Purchases of Federal Home Loan Bank of Boston stock	(1,390,000)	(832,000)
Proceeds from sales of buildings	5,834,000
Purchases of premises and equipment	(1,430,000)	(3,177,000)
Net cash used in investing activities	(73,365,000)	(64,056,000)
Cash flows from financing activities:
Net increase in non-brokered deposits	16,820,000	8,641,000
Net increase in brokered deposits	53,474,000	7,016,000
Net increase in short-term Federal Home Loan Bank of Boston borrowings	17,945,000	44,841,000
Repayments of long-term Federal Home Loan Bank of Boston advances	(4,863,000)	(7,554,000)
Net increase (decrease) in mortgagors' escrow accounts	1,222,000	(665,000)
Repurchases of common stock	(1,716,000)	(160,000)
Stock repurchase payable	70,000
Net cash provided by financing activities	82,952,000	52,119,000
Net change in cash and cash equivalents	(1,704,000)	(6,027,000)
Cash and cash equivalents at beginning of year	8,822,000	14,849,000
Cash and cash equivalents at end of year	7,118,000	8,822,000
Supplemental cash flow information:
Interest paid on deposits and borrowed funds	4,390,000	2,122,000
Income taxes paid, net of refunds	33,000	10,000
Non-cash items:
Leasehold improvements funded by landlord		646,000
Transfer of loan to foreclosed real estate		193,000
Transfer of portfolio loans to held for sale	3,051,000
Transfer of property and equipment to assets held for sale	$ 2,897,000	$ 828,000

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	1. Basis of Presentation The consolidated financial statements include the accounts of Randolph Bancorp, Inc. (a Massachusetts corporation) and its wholly-owned subsidiary, Envision Bank (together, the “Company”). The Bank has subsidiaries involved in owning investment securities and foreclosed real estate and a subsidiary which provides loan closing services. All intercompany accounts and transactions have been eliminated in consolidation. Nature of Operations The Bank, which changed its name from Randolph Savings Bank to Envision Bank on March 12, 2018, provides a variety of financial services to individuals and small businesses through its five branch offices in Massachusetts. The Bank’s primary deposit products are checking, savings and term certificate accounts and its primary lending products are residential and commercial mortgage loans. The Bank is also actively involved in the sale and servicing of residential mortgage loans in the secondary market. The Federal Deposit Insurance Corporation (“FDIC”) provides insurance coverage on all deposits up to $250,000 per depositor. As an FDIC insured institution, the Bank is subject to supervision, examination and regulation by the FDIC. Additionally, as a Massachusetts chartered savings bank, the Bank’s depositors are also insured by the Depositors Insurance Fund (“DIF”), a private industry-sponsored insurance company. The DIF insures bank deposits in excess of the FDIC insurance limits. The following significant accounting and reporting policies of the Company conform to U.S. generally accepted accounting principles (“GAAP”) and are used in preparing and presenting these consolidated financial statements. Use of estimates In preparing consolidated financial statements in conformity with GAAP, management is required to make estimates and assumptions that affect the reported amounts of assets and liabilities as of the date of the consolidated balance sheet and reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Material estimates that are particularly susceptible to significant change in the near term relate to the allowance for loan losses, mortgage servicing rights, deferred tax assets and fair value measurements. Cash and cash equivalents Cash equivalents include amounts due from banks, federal funds sold on a daily basis and interest-bearing deposits with original maturities of ninety days or less. Certificates of deposit Certificates of deposit have original maturities ranging from one to five years and are carried at cost. Fair value hierarchy The Company groups its assets and liabilities that are measured at fair value in three levels based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. Level 1 – Valuation is based on quoted prices in active markets for identical assets and liabilities. Valuations are obtained from readily available pricing sources. Level 2 – Valuation is based on observable inputs other than Level 1 prices, such as quoted prices for similar assets and liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets and liabilities. Level 3 – Valuation is based on unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets and liabilities. Level 3 assets and liabilities include those for which the value is determined using unobservable inputs to pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation. Transfers between levels are recognized at the end of a reporting period, if applicable. Securities All securities are classified as available for sale and are recorded at fair value, with unrealized gains and losses excluded from earnings and reported in other comprehensive income/loss. Purchase premiums and discounts are recognized in interest income using the level yield method over the terms of the securities. Anticipated prepayments on mortgage-backed securities are used in applying this method. Gains and losses on the sale of securities are recorded on the trade date and are determined using the weighted average cost method for mutual funds and the specific identification method for other securities. On a quarterly basis, the Company evaluates all securities with a decline in fair value below the amortized cost of the investment to determine whether or not the impairment is deemed to be other than temporary (“OTTI”). OTTI is required to be recognized (1) if the Company intends to sell the security; (2) if it is “more likely than not” that the Company will be required to sell the security before recovery of its amortized cost basis; or (3) for debt securities, if the present value of expected cash flows is not sufficient to recover the entire amortized cost basis. For all impaired debt securities that the Company intends to sell, or more likely than not will be required to sell, the full amount of the decline in fair value is recognized as OTTI through earnings. For all other impaired debt securities, credit-related OTTI is recognized through earnings and non-credit related OTTI is recognized in other comprehensive income/loss, net of applicable taxes. Because the Company’s assessments are based on available factual information as well as subjective information, the determination as to whether an OTTI exists and, if so, the amount of impairment, is subjective and, therefore, the timing and amount of OTTI constitute material estimates that are subject to significant change. Federal Home Loan Bank of Boston stock The Bank, as a member of the Federal Home Loan Bank of Boston (“FHLBB”), is required to maintain an investment in capital stock of the FHLBB. Based on redemption provisions of the FHLBB, the stock has no quoted market value and is carried at cost. The Company periodically evaluates for impairment based on ultimate recovery of its cost basis in the FHLBB stock. Loans held for sale and related derivatives The origination of residential mortgage loans is an integral part of the Company’s business. The Company generally sells its originations of such loans in the secondary market to either government-sponsored enterprises (“GSEs”) or other financial institutions. The servicing of loans sold to GSEs is initially retained while loans sold to other financial institutions are generally done on a servicing released basis. The Bank utilizes the fair value option pursuant to Accounting Standards Codification (“ASC”) 825, “Financial Instruments” for its residential mortgage loans being held for sale. Fair value is determined based on either commitments in effect from investors or prevailing market price and include the value of mortgage servicing rights. Gains and losses on the sales of loans are determined using the specific identification method. In determining the amount of the gain or loss the Company takes into consideration the direct costs of originating the loan. Also included in the net gain on loan origination and sale activities presented in the accompanying statements of operations are fair value adjustments for mortgage banking derivatives (interest rate lock commitments with borrowers, and forward loan sale commitments with investors for the delivery of mortgage loans to third party investors including To Be Announced securities (“TBAs”)) and loans held for sale. Loans The Company grants residential real estate, commercial real estate, construction, commercial and consumer loans to customers. A substantial portion of the loan portfolio is represented by mortgage loans in eastern Massachusetts and Rhode Island. The ability of the Company’s borrowers to honor their contracts is affected by real estate values and general economic conditions in these markets. Loans that management has the intent and ability to hold for the foreseeable future or until maturity or pay-off are reported at their outstanding unpaid principal balances adjusted for charge-offs, the allowance for loan losses, and net deferred loan origination fees and costs and purchase premiums. Interest income is accrued on the unpaid principal balance. Certain direct loan origination costs and purchase premiums, net of origination fees, are deferred and recognized in interest income using the level yield method without anticipating prepayments. Interest is not accrued on loans which are ninety days or more past due, or when, in the judgment of management, the collectability of the principal or interest becomes doubtful. Past due status is based on contractual terms of the loan. Interest income previously accrued on such loans is reversed against current period earnings. Loans are returned to accrual status when all principal and interest amounts contractually due are brought current and future payments are reasonably assured. Allowance for loan losses The allowance for loan losses is a valuation allowance for probable incurred credit losses. Loan losses are charged against the allowance when management believes the uncollectibility of a loan balance is confirmed. Subsequent recoveries, if any, are credited to the allowance. The allowance for loan losses is evaluated on a regular basis and is based upon management’s periodic review of the collectibility of the loans in light of historical experience, the nature and volume of the loan portfolio, adverse situations that may affect the borrower’s ability to repay, estimated value of any underlying collateral and prevailing economic conditions. This evaluation is inherently subjective as it requires estimates that are susceptible to significant revision as either additional information becomes available or circumstances change. The allowance for loan losses is allocated to loan types using both a formula-based approach applied to groups of loans (general component) and an analysis of certain individual loans for impairment (allocated component). General component The general component of the allowance for loan losses covers loans that are collectively evaluated for impairment and is based on historical loss experience adjusted for qualitative factors stratified by loan segments. Management uses a rolling average of historical losses based on a trailing 48 month time frame appropriate to capture relevant loss data for each loan segment. This historical loss factor is supplemented by the following qualitative factors: levels/trends in delinquencies; trends in volume and terms of loans; effects of changes in risk selection and underwriting standards and other changes in lending policies, procedures and practices; experience/ability/depth of lending management and staff; national and local economic trends and conditions, regulatory and legal factors; and risk rating concentrations. The qualitative factors are determined based on the various risk characteristics of each loan segment. Risk characteristics relevant to each portfolio segment are as follows: Residential one-to-four family real estate – The Company generally does not originate loans with a loan-to-value ratio greater than 80 percent. All loans in this segment are collateralized by one-to-four family owner, and non-owner-occupied, residential real estate and repayment is dependent on the credit quality of the individual borrower. The overall health of the economy, including unemployment rates and housing prices, will have an effect on the credit quality in this segment. Second mortgages and home equity lines of credit (HELOC) – Loans in this segment are primarily secured by second-position liens, and the Company may or may not also have a first-position lien. Regardless of which creditor is in first position, the Company does not originate loans with a combined loan-to-value ratio greater than 80 percent. All loans in this segment are collateralized by owner-occupied residential real estate and repayment is dependent on the credit quality of the individual borrower. The overall health of the economy, including unemployment rates and housing prices, will have an effect on the credit quality in this segment. Commercial real estate – Loans in this segment consist of owner-occupied and non-owner-occupied property throughout Massachusetts and Rhode Island. The underlying cash flows generated by the operating entities of owner-occupied real estate support the associated debt. Rental cash flows, for which management obtains periodic rent rolls, support the debt associated with non-owner-occupied real estate and can be negatively impacted by increased vacancy rates. Construction – Loans in this segment primarily include residential real estate development loans for which payment is derived from sale of the property. Credit risk is affected by cost overruns, time to sell at an adequate price, and market conditions. Commercial and Industrial – Loans in this segment are made to businesses and are generally secured by assets of the business. Repayment is expected from the cash flows of the business. A weakened economy, and resultant decreased consumer spending, would have an effect on the credit quality in this segment. Consumer – Loans in this segment primarily include personal unsecured loans, refinanced student loans and auto loans purchased from third party lenders. Repayment is dependent on the credit quality of the individual borrower. Allocated component The allocated component of the allowance for loan losses relates to loans that are individually classified as impaired. Residential real estate, commercial and industrial, commercial real estate and construction loans are evaluated for impairment on a loan-by-loan basis. Impairment is measured by either the present value of expected future cash flows discounted at the loan’s effective interest rate, or the fair value of the collateral if the loan is collateral dependent. An allowance is established when the discounted cash flows (or collateral value) of the impaired loan are lower than the carrying value of that loan. Large groups of smaller balance homogeneous loans are collectively evaluated for impairment. Accordingly, the Company does not generally identify individual consumer loans or second mortgages and HELOCs for impairment disclosures unless such loans are 90 days past due or are classified as a troubled debt restructuring. A loan is considered impaired when, based on current information and events, it is probable that the Company will be unable to collect the scheduled payments of principal or interest when due according to the contractual terms of the loan agreement. Factors considered by management in determining impairment include payment status, collateral value, and the probability of collecting scheduled principal and interest payments when due. Loans that experience insignificant payment delays and payment shortfalls generally are not classified as impaired. Management determines the significance of payment delays and payment shortfalls on a case-by-case basis, taking into consideration all of the circumstances surrounding the loan and the borrower, including the length of the delay, the reasons for the delay, the borrower’s prior payment record, and the amount of the shortfall in relation to the principal and interest owed. The Company periodically may agree to modify the contractual terms of loans. When a loan is modified and a concession is made to a borrower experiencing financial difficulty, the modification is considered a troubled debt restructuring (“TDR”). All TDRs are classified as impaired. Bank-owned life insurance Bank-owned life insurance policies are reflected on the consolidated balance sheets at their cash surrender value net of charges or other amounts that are probable at settlement. Changes in the net cash surrender value of the policies, as well as insurance proceeds received, are reflected in non-interest income in the consolidated statements of operations and are not subject to income taxes, unless such policies are surrendered prior to the death of the insured individuals. Mortgage servicing rights The Company services mortgage loans for others. Mortgage servicing rights are recognized as separate assets at fair value when rights are acquired through purchase or through sale of financial assets. Capitalized servicing rights are amortized into mortgage servicing income in proportion to, and over the period of, the estimated future net servicing income of the underlying financial assets. Servicing rights are evaluated for impairment based upon the fair value of the rights as compared to amortized cost. Impairment is determined by stratifying rights by predominant risk characteristics, such as interest rates and terms. Fair value is based on a valuation model that calculates the present value of estimated future net servicing income, using market-based assumptions. Impairment is recognized through a valuation allowance for an individual stratum, to the extent that fair value is less than the capitalized amount for the stratum. Changes in the valuation allowance, if any, are reported in mortgage servicing income. Premises and equipment Land is carried at cost. Buildings, equipment and leasehold improvements are stated at cost, less accumulated depreciation and amortization computed on the straight-line method over the estimated useful lives of the assets or the expected terms of the leases, if shorter. Expected terms include lease option periods to the extent that the exercise of such options is reasonably assured. Premises and equipment held for sale are stated at the lower of amortized cost or fair value less costs to sell. Transfers of financial assets Transfers of financial assets are accounted for as sales when control over the assets has been surrendered. Control over transferred assets is deemed to be surrendered when (1) the assets have been isolated from the Company, (2) the transferee obtains the right to pledge or exchange the transferred assets, and (3) the Company does not maintain effective control over the transferred assets through an agreement to repurchase them before their maturity. During the normal course of business, the Company may transfer a portion of a financial asset, for example, a participation loan. In order to be eligible for sales treatment, all cash flows from the loan must be divided proportionately, the rights of each loan holder must have the same priority, the loan holders must have no recourse to the transferor other than standard representations and warranties, and no loan holder can have the right to pledge or exchange the entire loan. In certain cases, the Company may have an obligation to repurchase mortgage loans sold to third parties and to refund fees to the purchaser if a payment default or prepayment occurs, in each case within a prescribed time period not exceeding four months after the sale date, or in the case of a violation of its representations and warranties under the provisions of its loan sale agreements. The Company evaluates its obligations under these provisions and recognizes a liability for the fair value of its recourse obligations. At December 31, 2018 and 2017, the Company determined that its obligations in connection with the recourse provisions of its loan sale agreements were insignificant. Foreclosed real estate Real estate acquired through, or in lieu of, loan foreclosure are held for sale and are initially recorded at fair value, less costs to sell, at the date of foreclosure, establishing a new cost basis. Subsequent to foreclosure, valuations are periodically performed by management and the assets are carried at the lower of carrying amount or fair value less costs to sell. Revenue and expenses from operations, changes in the valuation allowance and any direct write-downs are included in foreclosed real estate expense. Supplemental retirement plan The Company accounts for its supplemental retirement plan using an actuarial model that allocates cost over the service period of participants in the plan. The Company accounts for the over-funded or under-funded status of the plan as an asset or liability in its consolidated balance sheets and recognizes changes in the funded status in the year in which the changes occur through other comprehensive income/loss. Employee Stock Ownership Plan Compensation expense for the Employee Stock Ownership Plan (“ESOP”) is computed based on the number of shares allocated to participants during the period multiplied by the average fair market value of the Company’s shares. This expense is recognized ratably throughout the year based on the expected allocation of shares for the year. Unearned compensation applicable to the ESOP is reflected as a reduction of stockholders’ equity. The difference between the average fair market value and cost of the shares allocated by the ESOP is recorded as an adjustment to additional paid-in capital. Stock-based Compensation The fair value of restricted stock and stock options is determined on the date of grant and amortized to compensation expense with a corresponding increase to additional paid-in capital over the required service period, but in no event beyond the date of an employee’s or director’s date of termination. Forfeitures of unvested awards and grants are recorded as incurred. Advertising costs Advertising costs are expensed as incurred. Income taxes Deferred income tax assets and liabilities are determined using the liability (or balance sheet) method. Under this method, the net deferred tax asset or liability is determined based on the tax effects of the temporary differences between the book and tax basis of the various balance sheet assets and liabilities and gives current recognition to changes in tax rates and laws. A valuation allowance is established against deferred tax assets when, based upon available evidence including historical and projected taxable income, that some or all of the deferred tax assets will not be realized. A tax position is recognized as a benefit if it is “more likely than not” that the tax position would be sustained in a tax examination, with a tax examination being presumed to occur. The amount recognized is the largest amount of tax benefit greater than 50% likely of being realized on examination. For tax positions not meeting the “more likely than not” test, no tax benefit is recorded. The Company does not have any uncertain tax positions at December 31, 2018 and 2017 which require accrual or disclosure. The Company records interest and penalties as part of income tax expense. No interest or penalties were recorded for the years ended December 31, 2018 and 2017. Comprehensive income (loss) 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 equity, such items, along with net income (loss), are components of comprehensive income (loss). The components of accumulated other comprehensive loss (“AOCI”), included in stockholders’ equity, are as follows: December 31, December 31, 2018 2017 (In thousands) Securities available for sale: Net unrealized loss $ (1,334 ) $ (624 ) Tax effect (313 ) (313 ) Net-of-tax amount (1,647 ) (937 ) Supplemental retirement plan Unrecognized net actuarial loss (605 ) (667 ) Unrecognized net prior service credit 395 484 (210 ) (183 ) Tax effect (47 ) (47 ) Net-of-tax amount (257 ) (230 ) Accumulated other comprehensive loss $ (1,904 ) $ (1,167 ) In 2019, the Company expects to recognize $89,000 in prior service credits and $41,000 in net actuarial losses as components of cost for the supplemental retirement plan. These amounts are included in accumulated other comprehensive loss at December 31, 2018. Prior service credits and net actuarial gains and losses are amortized to periodic pension cost over varying periods based on the plan participants to whom they relate. Segment reporting Prior to 2018, the Company’s operations were managed, and financial performance was evaluated, by the chief operating decision-maker on a company-wide basis. As a result, management had determined there to be a single business segment for financial reporting purposes through December 31, 2017. Due to the significance of the Company’s mortgage banking operations and the strategic focus on this business, management prepared its 2018 operating budget by breaking-out its mortgage banking activities, including residential loan origination and loan servicing. As a result, effective January 1, 2018, the Company is reporting two business segments, namely, “Envision Bank” and “Envision Mortgage”. Comparative information for 2017 has been prepared on a basis consistent with the methodology used in 2018. As part of this process, management analyzed costs incurred by departments providing services to both segments (indirect costs), such as IT, Marketing, Accounting and Administration, to determine the allocation of indirect costs to each business segment in order to fully measure each segment’s results of operations. See Note 18 for disclosure of the Company’s segment information. Earnings (Loss) Per Share Basic earnings (loss) per share represents income (loss) available to common stockholders divided by the weighted average of common shares outstanding during the period. Unvested restricted shares of common stock having dividend rights are treated as “participating securities” and, accordingly, are considered outstanding in computing basic earnings (loss) per share. Unallocated ESOP shares are not considered outstanding in computing earnings (loss) per share. Diluted earnings per share reflects additional common shares that would have been outstanding if dilutive potential shares had been issued. Stock options represent potential dilutive shares with the number of such shares computed using the treasury method. No potential dilutive shares were considered in the computation of loss per share in 2018 and 2017 as the impact would be anti-dilutive. Business combinations We account for business combinations under the acquisition method of accounting. The application of this method of accounting requires the use of significant estimates and assumptions in the determination of the fair value of tangible and identified intangible assets acquired and liabilities assumed in order to properly allocate purchase price consideration between assets from those that are recorded as goodwill. Our estimates of the fair values of assets acquired and liabilities assumed are based upon assumptions that we believe to be reasonable, and whenever necessary, include assistance from independent third-party appraisal and valuation firms. Costs incurred to consummate a business combination are expensed as incurred. Recent accounting pronouncements In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers . This Update provides a revenue recognition framework for any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of non-financial assets unless those contracts are within the scope of other accounting standards. This ASU, as amended by ASU 2015-14, is effective for emerging growth companies in fiscal years beginning after December 15, 2018, including interim periods therein with early adoption permitted. The timing of the Company’s revenue recognition is not expected to materially change. The Company's revenue relates principally to financial instruments, which are explicitly excluded from the scope of the new guidance. Adoption of this standard on January 1, 2019 did not have a material impact on the Company’s consolidated financial statements. In January 2016, FASB issued ASU 2016-01, Financial Instruments In February 2016, FASB issued ASU 2016-02, Leases In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses In April 2017, the FASB issued ASU 2017-08 Receivables – Non-refundable Fees and Other Costs In August 2018, the FASB issued ASU 2018-13 Fair Value Measurement – Changes to the Disclosure Requirements for Fair Value Measurement, Reclassifications Certain reclassifications have been made to the 2017 consolidated financial statements in order to conform to the presentations used in the 2018 consolidated financial statements. Such reclassifications had no impact on net loss as presented in such financial statements .

Securities Available for Sale

Securities Available for Sale	12 Months Ended
	Dec. 31, 2018
Investments Debt And Equity Securities [Abstract]
Securities Available for Sale	2 . 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) December 31, 2018 Debt securities: U.S. Government-sponsored enterprises $ 3,999 $ 13 $ (31 ) $ 3,981 Corporate 1,524 6 (18 ) 1,512 Municipal 1,489 18 — 1,507 Residential mortgage-backed securities: U.S. Government-sponsored enterprises 26,989 71 (754 ) 26,306 Commercial mortgage-backed securities: U.S. Government-sponsored enterprises 9,094 — (487 ) 8,607 U.S. Government-guaranteed 1,796 — (33 ) 1,763 Collateralized mortgage obligations: U.S. Government-sponsored enterprises 1,642 — (17 ) 1,625 U.S. Government-guaranteed 4,839 2 (104 ) 4,737 Total debt securities 51,372 110 (1,444 ) 50,038 Mutual fund 518 — — 518 Total securities available for sale $ 51,890 $ 110 $ (1,444 ) $ 50,556 December 31, 2017 Debt securities: U.S. Government-sponsored enterprises $ 3,999 $ 50 $ (24 ) $ 4,025 Corporate 2,005 27 (8 ) 2,024 Municipal 12,707 179 (18 ) 12,868 Residential mortgage-backed securities: U.S. Government-sponsored enterprises 18,729 118 (450 ) 18,397 Commercial mortgage-backed securities: U.S. Government-sponsored enterprises 14,451 13 (403 ) 14,061 U.S. Government-guaranteed 2,132 — (6 ) 2,126 Collateralized mortgage obligations: U.S. Government-sponsored enterprises 1,871 12 (5 ) 1,878 U.S. Government-guaranteed 5,760 4 (100 ) 5,664 Total debt securities 61,654 403 (1,014 ) 61,043 Mutual fund 545 — (12 ) 533 Total securities available for sale $ 62,199 $ 403 $ (1,026 ) $ 61,576 The amortized cost and fair value of debt securities by contractual maturity at December 31, 2018 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 6,173 6,149 After 5 years through 10 years 839 851 7,012 7,000 Mortgage-backed securities and collaterlized mortgage obligations 44,360 43,038 $ 51,372 $ 50,038 Obligations of U.S. Government-sponsored enterprises consist primarily of securities issued by the Federal Home Loan Mortgage Corporation and the Federal National Mortgage Association. At December 31, 2018 and 2017, investment securities having a fair value of $2,010,000 and $2,004,000, respectively, were pledged as collateral for certain deposits and FHLBB borrowings. There were no individual holdings of investment securities at December 31, 2018 and 2017, other than holdings of the U.S. Government and its agencies, which exceeded 10% of the Company’s stockholders’ equity as of such dates. 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 December 31, 2018 (In thousands) Debt securities: U.S. Government-sponsored enterprises $ — $ — $ (31 ) $ 1,969 Corporate (5 ) 497 (13 ) 506 Municipal — — — — Residential mortgage-backed securities: U.S. Government-sponsored enterprises (6 ) 7,038 (748 ) 12,981 Commercial mortgage-backed securities: U.S. Government-sponsored enterprises — — (487 ) 8,607 U.S. Government-guaranteed — — (33 ) 1,763 Collateralized mortgage obligations: U.S. Government-sponsored enterprises — — (17 ) 1,625 U.S. Government-guaranteed — — (104 ) 3,879 Total debt securities $ (11 ) $ 7,535 $ (1,433 ) $ 31,330 December 31, 2017 Debt securities: U.S. Government-sponsored enterprises $ — $ — $ (24 ) $ 19,676 Corporate — — (8 ) 988 Municipal (11 ) 1,919 (7 ) 479 Residential mortgage-backed securities: U.S. Government-sponsored enterprises (1 ) 1,623 (449 ) 13,163 Commercial mortgage-backed securities: U.S. Government-sponsored enterprises — — (403 ) 8,805 U.S. Government-guaranteed (6 ) 2,126 — — Collateralized mortgage obligations: U.S. Government-sponsored enterprises (5 ) 678 — — U.S. Government-guaranteed (1 ) 295 (99 ) 3,756 Total debt securities (24 ) 6,641 (990 ) 46,867 Mutual fund — — (12 ) 533 $ (24 ) $ 6,641 $ (1,002 ) $ 47,400 At December 31, 2018, 35 debt securities have unrealized losses with aggregate depreciation of 3.58% from the Company’s amortized cost basis. The unrealized losses at December 31, 2018, which related primarily to securities issued by U.S. government-sponsored enterprises, were primarily caused by interest rate increases over the past two years. 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 December 31, 2018. For the year ended December 31, 2018, proceeds from the sale of securities amounted to $8,958,000 which resulted in a realized gain of $49,000. In addition, losses of $33,000 and $27,000 were recognized upon prepayment of a commercial mortgage-backed security and an OTTI write-down of a mutual fund, respectively, in 2018.

Loans

Loans	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Loans	3 . LOANS A summary of the loan portfolio is as follows: December 31, 2018 2017 (In thousands) Mortgage loans on real estate: Residential: One-to-four family $ 246,756 $ 198,475 Home equity loans and lines of credit 43,545 38,968 Commercial 113,642 98,755 Construction 42,139 25,357 446,082 361,555 Commercial and industrial 21,285 24,766 Consumer 19,407 16,337 Total loans 486,774 402,658 Allowance for loan losses (4,437 ) (3,737 ) Net deferred loan costs and fees, and purchase premiums 1,509 1,452 $ 483,846 $ 400,373 The Company has transferred a portion of its originated commercial real estate loans to participating lenders. The amounts transferred have been accounted for as sales and are therefore not included in the Company’s accompanying consolidated balance sheets. The Company and participating lenders share ratably in any gains or losses that may result from a borrower’s lack of compliance with contractual terms of the loan. The Company continues to service the loans on behalf of the participating lenders and, as such, collects cash payments from the borrowers, remits payments (net of servicing fees) to participating lenders and disburses required escrow funds to relevant parties. At December 31, 2018 and 2017, the Company was servicing loans for participants aggregating $5,596,000 and $5,902,000, respectively. See Note 4 for information relating to the Company’s servicing of residential mortgage loans for others. The following table presents activity in the allowance for loan losses, by loan category, for the years ended December 31, 2018 and 2017 and allocation of the allowance to each category as of such dates: Second Residential Mortgages Commercial Commercial 1-4 Family and HELOC Real Estate Construction and Industrial Consumer Total (In thousands) Allowance for loan losses Balance at December 31, 2016 $ 1,018 $ 436 $ 1,410 $ 225 $ 37 $ 145 $ 3,271 Provision (credit) for loan losses (187 ) (77 ) 210 126 263 205 540 Loans charged-off — — — — — (153 ) (153 ) Recoveries 23 — — — 35 21 79 Balance at December 31, 2017 854 359 1,620 351 335 218 3,737 Provision (credit) for loan losses 197 (67 ) 30 414 (70 ) 258 762 Loans charged-off — — (2 ) — — (119 ) (121 ) Recoveries 41 — — — — 18 59 Balance at December 31, 2018 $ 1,092 $ 292 $ 1,648 $ 765 $ 265 $ 375 $ 4,437 Second Residential Mortgages Commercial Commercial 1-4 Family and HELOC Real Estate Construction and Industrial Consumer Total December 31, 2018 Allowance for impaired loans $ 108 $ — $ — $ — $ — $ 174 $ 282 Allowance for non-impaired loans 984 292 1,648 765 265 201 4,155 Total allowance for loan losses $ 1,092 $ 292 $ 1,648 $ 765 $ 265 $ 375 $ 4,437 Impaired loans $ 6,291 $ 408 $ 52 $ — $ — $ 199 $ 6,950 Non-impaired loans 240,465 43,137 113,590 42,139 21,285 19,208 479,824 Total loans $ 246,756 $ 43,545 $ 113,642 $ 42,139 $ 21,285 $ 19,407 $ 486,774 December 31, 2017 Allowance for impaired loans $ 160 $ 1 $ 1 $ — $ — $ — $ 162 Allowance for non-impaired loans 694 358 1,619 351 335 218 3,575 Total allowance for loan losses $ 854 $ 359 $ 1,620 $ 351 $ 335 $ 218 $ 3,737 Impaired loans $ 5,205 $ 276 $ 352 $ — $ — $ — $ 5,833 Non-impaired loans 193,270 38,692 98,403 25,357 24,766 16,337 396,825 Total loans $ 198,475 $ 38,968 $ 98,755 $ 25,357 $ 24,766 $ 16,337 $ 402,658 The following table presents past due and non-accrual loans, by loan category, at December 31, 2018 and 2017: 30 - 59 Days Past Due 60 - 89 Days Past Due 90 Days or More Past Due Total Past Due Non-accrual Loans (In thousands) December 31, 2018 Residential one-to-four family $ 655 $ 207 $ 635 $ 1,497 $ 2,474 Home equity loans and lines of credit 520 — — 520 407 Commercial real estate — — — — — Construction — — — — — Commercial and industrial — — — — — Consumer 25 4 — 29 149 Total $ 1,200 $ 211 $ 635 $ 2,046 $ 3,030 December 31, 2017 Residential one-to-four family $ 737 $ — $ — $ 737 $ 1,975 Home equity loans and lines of credit 96 — — 96 276 Commercial real estate — — — — — Construction — — — — — Commercial and industrial — — — — — Consumer — — — — — Total $ 833 $ — $ — $ 833 $ 2,251 Further information pertaining to impaired loans, which includes both non-accrual loans and troubled debt restructurings, follows: Recorded Investment Unpaid Principal Balance Related Allowance (In thousands) December 31, 2018 Impaired loans without a valuation allowance: Residential one-to-four family $ 4,280 $ 4,280 $ — Home equity loans and lines of credit 408 408 — Commercial real estate 52 52 — Total 4,740 4,740 — Impaired loans with a valuation allowance: Residential one-to-four family 2,011 2,011 108 Consumer 199 199 174 Total 2,210 2,210 282 Total impaired loans $ 6,950 $ 6,950 $ 282 December 31, 2017 Impaired loans without a valuation allowance: Residential one-to-four family $ 2,641 $ 2,641 $ — Home equity loans and lines of credit 247 247 — Commercial real estate 257 257 — Total 3,145 3,145 — Impaired loans with a valuation allowance: Residential one-to-four family 2,564 2,564 160 Home equity loans and lines of credit 29 29 1 Commercial real estate 95 95 1 Total 2,688 2,688 162 Total impaired loans $ 5,833 $ 5,833 $ 162 Information related to the average balances of impaired loans and the interest income recognized on such loans, follows: Average Interest Cash Basis Recorded Income Interest Investment Recognized Recognized (In thousands) Year Ended December 31, 2018 Residential one-to-four family $ 6,781 $ 210 $ 84 Home equity loans and lines of credit 420 36 36 Commercial real estate 244 15 — Consumer 50 2 — Total $ 7,495 $ 263 $ 120 Year Ended December 31, 2017 Residential one-to-four family $ 4,956 $ 195 $ 82 Home equity loans and lines of credit 276 1 1 Commercial real estate 655 36 — Total $ 5,887 $ 232 $ 83 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. 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. At December 31, 2018, the Company had seventeen residential real estate loans and one commercial real estate loan aggregating $3,341,000 and $52,000, respectively, which were subject to troubled debt restructuring agreements. At December 31, 2017, the Company had nineteen residential real estate loans and two commercial real estate loans aggregating $4,315,000 and $153,000, respectively, which were subject to troubled debt restructuring agreements. As of December 31, 2018 and 2017, $3,341,000 and $4,315,000, respectively, in troubled debt restructurings were performing in accordance with the terms of the modified loan agreements. Included in such amounts are $366,000 and $1,085,000, respectively, that are being accounted for as non-accrual loans. For the year ended December 31, 2018 the Company entered into one loan modification meeting the criteria of a troubled debt restructuring in which a loan term concession was granted to a borrower. For the year ended December 31, 2017. the Company did not enter into any loan modifications meeting the criteria of a troubled debt restructuring. 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. At December 31, 2018 and 2017 allowances of $282,000 and $162,000, respectively, related to troubled debt restructurings. During the years ended December 31, 2018 and 2017, 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 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 at December 31, 2018 and 2017: December 31, 2018 December 31, 2017 Commercial Real Construction Commercial and Industrial Commercial Real Construction Commercial and Industrial (In thousands) Loans rated 1 - 3A $ 113,642 $ 42,139 $ 21,285 $ 98,556 $ 25,357 $ 24,766 Loans rated 4 — — — — — — Loans rated 5 — — — 199 — — $ 113,642 $ 42,139 $ 21,285 $ 98,755 $ 25,357 $ 24,766 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 of these loans becomes more than 90 days delinquent it is assigned an internal loan rating. At December 31, 2018, one consumer loan for $149,000 was rated as doubtful, $2,469,000 in residential mortgages and one consumer loan for $50,000 were rated as substandard and $936,000 in residential mortgages and $407,000 in home equity lines of credit were rated as special mention. At December 31, 2017, $712,000 in residential mortgages were rated as substandard and $2,512,000 in residential mortgages and $247,000 in home equity lines of credit were rated as special mention .

Loan Servicing

Loan Servicing	12 Months Ended
	Dec. 31, 2018
Transfers And Servicing [Abstract]
Loan Servicing	4 . LOAN SERVICING Mortgage loans serviced for others are not included in the accompanying consolidated balance sheets. The unpaid principal balances of mortgage loans serviced for others were $929,289,000 and $771,407,000 at December 31, 2018 and 2017, respectively. The following table summarizes the activity in the Company’s mortgage servicing rights for the indicated periods: For the Year Ended December 31, 2018 2017 Mortgage servicing rights: (In thousands) Balance at beginning of year $ 6,397 $ 8,486 Additions through originations 2,380 2,310 Amortization (983 ) (1,071 ) Sales — (3,238 ) Balance at end of year $ 7,794 $ 6,487 Valuation allowance: Balance at beginning of year $ 90 $ 424 Provision (credit) (82 ) (334 ) Balance at end of year $ 8 $ 90 Mortgage servicing rights, amortized cost $ 7,786 $ 6,397 Mortgage servicing rights, fair value $ 8,554 $ 6,485 At December 31, 2018 and 2017, the fair value of servicing rights was determined using a discount rate of 12% and 13%, respectively, and projected annual prepayment speeds ranging from 7% to 35% for 2018 and 6% to 24% for 2017. Contractually specified servicing fees for the years ended December 31, 2018 and 2017 amounted to $2,165,000 and $2,434,000, respectively, and are included in mortgage servicing fees, net.

Premises and Equipment

Premises and Equipment	12 Months Ended
	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Premises and Equipment	5 . PREMISES AND EQUIPMENT A summary of the cost and accumulated depreciation and amortization of premises and equipment is as follows: December 31, Estimated 2018 2017 Useful Life (In thousands) (In years) Land and improvements $ 1,025 $ 2,525 Buildings and improvements 3,280 4,457 5 to 50 Leasehold improvements 2,136 1,503 3 to 10 Furniture and equipment 5,032 4,765 3 to 10 Construction-in-progress 84 101 11,557 13,351 Less accumulated depreciation and amortization (5,189 ) (4,681 ) $ 6,368 $ 8,670 Total depreciation and amortization expense for the years ended December 31, 2018 and 2017 amounted to $835,000 and $605,000, respectively. During 2017, the Company amended the lease for its Andover loan operations center relocating offices within an office complex. As part of this lease amendment, the landlord funded the cost of leasehold improvements which amounted to $646,000. These costs have been capitalized as part of premises and equipment and a tenant improvement allowance has been recorded as part of other liabilities in the accompanying consolidated balance sheet. Both the leasehold improvements and tenant improvement allowance are being amortized over the initial lease term of approximately five years. In July 2018, the Company entered into a sublease agreement for 27% of the space in its Andover location. This sublease commenced on October 1, 2018 and runs co-terminus with the Company’s lease which expires in March 2023. In October 2018, the Board of Directors approved a plan to consolidate mortgage banking operations in the Company’s North Attleboro loan operations center (see Note 20 for additional information). As part of this decision, certain mortgage banking employees not directly involved in the loan origination process remained at the Andover location. Based on an analysis of space needs for the remaining employees, the area not currently under sublease was subdivided resulting in approximately half of the total leased space in Andover, or 8,600 square feet, becoming available for sublease. In connection with these actions, the Company recognized a fair value “cease use” liability of $565,000 based on expected future cash flows which is included in the restructuring charge recorded in the fourth quarter of 2018. In estimating this liability, the Company assumed that the sublease for the 8,600 square feet of available space would commence in April 2020. In addition to the cease use liability, the Company also recognized an impairment write-down of $168,000 for furniture and equipment which is no longer expected to be used in operations. This write-down is also included in the restructuring charge recorded in the fourth quarter of 2018. During 2018, the Company sold three branch buildings, two of which were replaced by newly constructed or leased locations. These buildings were reclassified to assets held for sale at the lower of their net book value or fair value and at December 31, 2017 had a carrying value of $828,000. An impairment write-down of $225,000 was recognized in 2017 and a loss on sale of $15,000 in 2018 for one of these buildings. During 2018, the other building was sold and a gain of $230,000 was recognized. In December 2018, the Company sold its branch building in Boston for cash consideration of $5,000,000 and recognized a gain of $2,261,000. Earlier in 2018, this building experienced significant water damage resulting in an insurance claim. The Company recognized an insurance recovery of $90,000 for personal property damages which is included in other non-interest income. The insurance recovery for building damage, which was received in December 2018, is included in the gain on sale of the building.

Deposits

Deposits	12 Months Ended
	Dec. 31, 2018
Deposits [Abstract]
Deposits	6 . DEPOSITS A summary of deposit balances, by type, is as follows: December 31, 2018 2017 (In thousands) Demand deposits $ 64,229 $ 62,130 NOW accounts 42,802 44,988 Money market deposits 60,843 56,668 Regular and other savings 101,137 102,528 Brokered deposits 10,088 7,106 Total non-certificate accounts 279,099 273,420 Term certificates less than $250,000 99,491 80,538 Term certificates of $250,000 or more 8,048 12,878 Term certificates - brokered 50,492 — Total certificate accounts 158,031 93,416 $ 437,130 $ 366,836 A summary of term certificates, including brokered deposits, by maturity is as follows: December 31, 2018 December 31, 2017 Weighted Weighted Average Average Maturing during: Amount Rate Amount Rate (Dollars in thousands) 2018 $ — — % 49,550 0.84 % 2019 89,167 1.68 22,470 1.20 2020 40,847 2.16 8,754 1.44 2021 12,785 2.16 4,873 1.57 2022 14,101 1.98 7,769 1.65 2023 1,131 1.38 — — $ 158,031 1.87 % $ 93,416 1.09 %

Borrowings

Borrowings	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Borrowings	7 . BORROWINGS A summary of borrowings from the FHLBB at December 31, 2018 and 2017 is as follows: 2018 2017 Weighted Weighted Average Average Amount Rate Amount Rate (Dollars in thousands) Fixed-rate advances maturing: 2018 $ — — % $ 69,337 1.55 % 2019* 84,184 2.57 1,500 1.00 2020* 2,894 1.49 3,129 1.52 2021* 1,958 1.33 1,988 1.34 $ 89,036 2.50 % $ 75,954 1.54 % * Includes amortizing advances which require monthly principal and interest payments. Included in FHLBB borrowings at December 31, 2018 and 2017 are overnight advances and advances having a one-month maturity of $82.7 million and $64.7 million, respectively. Selected information for such short-term borrowings for the years presented is as follows (in 000’s): 2018 2017 Average daily balance $ 63,552 $ 34,656 Maximum outstanding at any month end 108,819 64,739 Advances from the FHLBB are secured by a blanket pledge agreement on the Bank’s qualified collateral, defined principally as 75% of the carrying value of pledged first mortgage loans on owner-occupied residential property and 65% on pledged commercial real estate loans. Available borrowing capacity at December 31, 2018 was $90,346,000. At December 31, 2018, the Bank was in compliance with the FHLBB collateral requirements. The Bank also has a $4,195,000 available line of credit with the FHLBB at an interest rate that adjusts daily. Borrowings under the line are limited to 2% of the Bank’s total assets. At December 31, 2018 and 2017, there were no advances outstanding. The Bank also has a $10,000,000 available line of credit with the Federal Reserve Bank of Boston. No advances were outstanding at December 31, 2018 and 2017. The Bank also has a $7,500,000 available line of credit with a correspondent bank. No advances were outstanding at December 31, 2018 and 2017.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	8 . INCOME TAXES Allocation of federal and state income taxes between current and deferred portions is as follows (in thousands): Years Ended December 31, 2018 2017 Current tax expense (benefit): Federal $ — $ (462 ) State 31 19 Total current tax expense (benefit) 31 (443 ) Deferred tax expense (benefit): Federal (541 ) (518 ) Effect of change in federal tax rate — 1,627 State 73 (23 ) (468 ) 1,086 Change in valuation allowance 468 541 Effect of change in federal tax rate - valuation allowance — (1,627 ) Total deferred tax expense — — Total tax expense (benefit) $ 31 $ (443 ) The reasons for the differences between the statutory federal income tax expense (benefit) and the actual tax expense (benefit) are summarized as follows (in thousands): Years Ended December 31, 2018 2017 Statutory federal tax (21% in 2018 and 34% in 2017) $ (432 ) $ (874 ) Increase (decrease) resulting from: State taxes, net of federal tax effect 83 (3 ) Bank-owned life insurance (46 ) (52 ) Tax exempt income (25 ) (118 ) Dividends received deduction — (5 ) Change in valuation allowance 468 541 Change in AOCI deferred effect — (36 ) Effect of change in federal tax rate — 1,627 Effect of change in federal tax rate-valuation allowance — (1,627 ) Other, net (17 ) 104 Total tax expense (benefit) $ 31 $ (443 ) The federal tax benefit in 2017 results from repeal of the alternative minimum tax (“AMT”) under the Tax Cuts and Jobs Act of 2017 (the “Tax Act”) which was signed into law on December 22, 2017. The Tax Act also provides that existing AMT credit carryforwards be refunded over the next four years. The Tax Act includes a number of changes in existing tax law impacting businesses including, among other things, a permanent reduction in the corporate income tax rate from 35% to 21% effective on January 1, 2018 and repeal of the AMT. As a result of these changes, the Company revalued its net deferred tax asset as of December 22, 2017 resulting in a reduction in the value of the net deferred tax asset of $1,627,000 which was offset by a corresponding decrease in the valuation allowance. The components of the net deferred tax asset are as follows (in thousands): December 31, 2018 2017 Deferred tax assets: Federal $ 5,134 $ 4,247 State 1,134 1,008 6,268 5,255 Valuation allowance (3,246 ) (2,778 ) 3,022 2,477 Deferred tax liabilities: Federal (2,189 ) (1,806 ) State (833 ) (671 ) (3,022 ) (2,477 ) Net deferred tax asset $ — $ — The tax effects of items giving rise to deferred tax assets (liabilities) are as follows (in thousands): December 31, 2018 2017 Employee benefit plans $ 825 $ 951 Allowance for loan losses 1,247 1,050 Funded status of post-retirement benefits (47 ) (47 ) Securities available for sale (313 ) (313 ) Depreciation and amortization 249 193 Net deferred loan origination costs (357 ) (321 ) Mortgage servicing rights (2,082 ) (1,624 ) Net operating loss carryforward 2,864 2,171 Charitable contribution carryforward 700 702 Derivatives (105 ) (98 ) Stock-based compensation 121 48 Other, net 144 66 3,246 2,778 Valuation allowance on deferred tax assets (3,246 ) (2,778 ) Net deferred tax asset $ — $ — At December 31, 2018, the Company has a federal net operating loss carryforward of $13,638,000, of which $4,745,000 expires on December 31, 2033, $406,000 expires on December 31, 2034, $1,542,000 expires on December 31, 2035, $501,000 expires on December 31, 2036, $2,871,000 expires on December 31, 2037 and $3,573,000 has no expiration. At December 31, 2018, the Company has a charitable contribution carryforward of $2,481,000 of which all but $174,000 expires on December 31, 2021. Since 2014, the Company has maintained a valuation allowance for all of its deferred tax assets based on a determination that it was more likely than not that such assets would not be realized. This determination was based on the Company’s net operating loss (“NOL”) carryforward position, its current period operating results exclusive of non-recurring items and its expectations for the upcoming year. In performing subsequent assessments, management has concluded that no significant changes in the key factors affecting the realizability of the deferred tax asset has occurred and that a valuation allowance for all deferred tax assets should be maintained. The federal income tax reserve for loan losses at the Company’s base year amounted to $2,033,000. If any portion of the reserve is used for purposes other than to absorb the losses for which it was established, approximately 150% of the amount actually used (limited to the amount of the reserve) would be subject to taxation in the fiscal year in which used. As the Company intends to use the reserve only to absorb loan losses, a deferred income tax liability of $571,000 has not been provided. The Company’s income tax returns are subject to review and examination by federal and state taxing authorities. The Company is currently open to audit under the applicable statutes of limitations by the Internal Revenue Service for the years ended December 31, 2015 through 2018. The years open to examination by state taxing authorities vary by jurisdiction; no years prior to 2015 are open.

On-Balance Sheet Derivative Ins

On-Balance Sheet Derivative Instruments and Hedging Activities	12 Months Ended
	Dec. 31, 2018
Derivative Instruments And Hedging Activities Disclosure [Abstract]
On-Balance Sheet Derivative Instruments and Hedging Activities	9 . ON-BALANCE SHEET DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES Derivative Loan Commitments Mortgage loan interest rate lock 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 $36,852,000 and $24,222,000 at December 31, 2018 and 2017, respectively. The fair value of such commitments at December 31, 2018 and 2017 was an asset of $627,000 and $363,000, respectively, and is included in other assets in the consolidated balance sheets. During the years ended December 31, 2018 and 2017, the increase (reduction) in aggregate fair value of $264,000 and $(254,000), respectively, related to interest rate lock commitments were recognized and included in the net gain on loan origination and sales activities in the accompanying consolidated statements of operations. Forward Loan Sale Commitments The Company utilizes both “mandatory delivery” and “best efforts” forward loan sale commitments and, effective in the fourth quarter of 2018, TBA securities 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 expects that these forward loan sale commitments and TBA securities will experience changes in fair value that serve to offset the change in fair value of derivative loan commitments the degree to which depends on the notional amount of such sale commitments. The notional amount of forward loan sale commitments was $42,021,000 and $29,613,000 at December 31, 2018 and 2017, respectively, and liabilities of $263,000 and $19,000 at December 31, 2018 and 2017, respectively, are included in other liabilities in the consolidated balance sheets. The fair value of such commitments was an asset of $10,000 and $4,000 at December 31, 2018 and 2017, respectively, and are included in other assets in the consolidated balance sheets. During the years ended December 31, 2018 and 2017, reductions in aggregate fair value of $238,000 and $66,000, respectively, related to forward loan sale commitments were recognized and included in net gain on loan originations and sales activities in the accompanying consolidated statements of operations.

Minimum Regulatory Capital Requ

Minimum Regulatory Capital Requirements	12 Months Ended
	Dec. 31, 2018
Banking And Thrift [Abstract]
Minimum Regulatory Capital Requirements	1 0 . MINIMUM REGULATORY CAPITAL REQUIREMENTS The Bank is subject to various regulatory capital requirements administered by federal banking agencies. Capital adequacy guidelines and, additionally for banks, prompt corrective actions regulations, involve qualitative measures of assets, liabilities, and certain off-balance sheet items calculated under regulatory accounting practices. Capital amounts and classifications are also subject to qualitative judgement by regulators. Failure to meet capital requirements can initiate regulatory action. The final rules implementing Basel Committee on Banking Supervision’s capital guidelines for U.S. banks (Basel III rules) became effective for the Bank on January 1, 2015. Under BASEL III, community banking institutions must maintain a capital conservation buffer of common equity tier 1 capital in an amount greater than 2.5% of total risk-weighted assets to avoid being subject to limitations on capital distributions and discretionary bonuses. The capital conservation buffer is being phased in over three years with an initial phase-in of 0.625% (1.875% at December 31, 2018). Quantitative measures established by regulation to ensure capital adequacy require the Bank to maintain minimum amounts and ratios (set forth in the following tables) of total and Tier 1 capital to risk weighted assets Tier 1 capital to average assets and common equity Tier 1 capital (all as defined). Management believes, as of December 31, 2018 and 2017, that the Bank met all capital adequacy requirements to which it is subject. As of December 31, 2018, the most recent notification from the FDIC categorized the Bank as well capitalized under the regulatory framework for prompt corrective action. To be categorized as well capitalized, the Bank must maintain minimum total risk-based, Tier 1 risk-based, common equity Tier 1 and Tier 1 leverage ratios as set forth in the following tables. There are no conditions or events since the notification that management believes have changed the Bank’s category. The Bank’s actual and minimum capital amounts and ratios are presented in the following table: Minimum To Be Well For Minimum Capitalized Under Capital Prompt Corrective Actual Adequacy Purposes Action Provisions Amount Ratio Amount Ratio Amount Ratio (Dollars in thousands) December 31, 2018 Total capital (to risk weighted assets) $ 72,523 16.1 % $ 36,084 8.0 % $ 45,105 10.0 % Tier 1 capital (to risk weighted assets) 68,086 15.1 27,063 6.0 36,084 8.0 Common equity Tier 1 capital (to risk weighted assets) 68,086 15.1 20,297 4.5 29,318 6.5 Tier 1 capital (to average assets) 68,086 10.9 25,056 4.0 31,320 5.0 December 31, 2017 Total capital (to risk weighted assets) 73,612 20.4 28,896 8.0 36,120 10.0 Tier 1 capital (to risk weighted assets) 69,875 19.4 21,667 6.0 28,889 8.0 Common equity Tier 1 capital (to risk weighted assets) 69,875 19.4 16,250 4.5 23,472 6.5 Tier 1 capital (to average assets) 69,875 12.4 22,564 4.0 28,205 5.0

Post-retirement Plans

Post-retirement Plans	12 Months Ended
	Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Post-retirement Plans	1 1 . POST-RETIREMENT PLANS Supplemental retirement agreements The Company maintains supplemental retirement agreements with certain officers and directors (none of whom currently provide services to the Company) that provide for supplemental benefits commencing with retirement. The present value of future benefits payable is accrued over the terms of employment or anticipated term of each participating director’s position, as applicable, taking into consideration the vesting provisions in the agreements. At December 31, 2018 and 2017, the accrued benefits related to the agreements amounted to $549,000 and $607,000, respectively. Total expense, included in other non-interest expenses, related to these supplemental agreements amounted to $58,000 and $64,000 for the years ended December 31, 2018 and 2017, respectively. Supplemental retirement plan The Company has a master supplemental retirement plan (“Plan”) which covers certain officers and directors of the Company. In 2018 and 2017, the only active participants in the Plan were directors. Information pertaining to activity in the Plan follows: Years Ended December 31, 2018 2017 (In thousands) Change in plan assets: Fair value of plan assets at beginning of year $ — $ — Employer contributions 201 201 Benefits paid (201 ) (201 ) Fair value of plan assets at end of year — — Change in benefit obligation: Benefit obligation at beginning of year 1,724 1,836 Service cost 10 10 Interest cost 48 53 Actuarial (gain) loss (20 ) 26 Benefits paid (201 ) (201 ) Benefit obligation at end of year 1,561 1,724 Unfunded status and accrued supplemental pension cost at year end $ (1,561 ) $ (1,724 ) Accumulated benefit obligation at year end $ 1,561 $ 1,724 The assumptions used to determine the benefit obligation are as follows: December 31, 2018 2017 Discount rate 3.60 % 2.90 % Annual inflation factor 1.00 % 1.00 % Net periodic benefit cost, included in other non-interest expenses, attributable to the Plan for the years ended December 31, 2018 and 2017, consists of the following: 2018 2017 (In thousands) Service cost $ 10 $ 10 Interest cost 48 53 Amortization of net actuarial loss 41 38 Amortization of prior service credit (89 ) (89 ) $ 10 $ 12 The following assumptions were used to determine the net periodic benefit cost for the years ended December 31, 2018 and 2017: 2018 2017 Discount rate 2.90 % 3.05 % Annual inflation factor 1.00 % 1.00 % Estimated future benefit payments, which reflect expected future services, as appropriate, are as follows: Years Ending December 31, Amount (In thousands) 2019 $ 201 2020 201 2021 201 2022 213 2023 334 2024-2028 626 Endorsement split-dollar life insurance arrangements The Company is the sole owner of life insurance policies pertaining to certain of the Company’s directors and executives. The Company has entered into agreements with these directors and executives whereby the Company will pay to the directors’ and executives’ estates or beneficiaries a portion of the death benefit that the Company will receive as beneficiary of such policies. Expense associated with this post-retirement benefit for the years ended December 31, 2018 and 2017 amounted to $16,000 and $22,000, respectively. At December 31, 2018 and 2017, the accrued benefits related to the split-dollar arrangements amounted to $435,000 and $419,000, respectively. 401(k) Plan The Company maintains a 401(k) Plan whereby each employee reaching the age of 21 automatically becomes a participant in the plan. Employees may contribute up to 15% of their compensation subject to certain limits based on federal tax laws. All employees who have worked for one year or 1,000 hours are eligible for an automatic employer contribution of 3% of employees’ compensation, which includes no vesting period. The Company also matches 50% of the first 2% of an eligible employee’s contributions, allowing for a total employer contribution of 4% of employees’ compensation. Matching contributions vest over a four year service period. In addition, a profit sharing provision allows for an additional discretionary contribution by the Company upon approval of the Board of Directors. For the years ended December 31, 2018 and 2017, expenses attributable to the plan amounted to $580,000 and $583,000, respectively.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	1 2 . STOCK-BASED COMPENSATION Under the Randolph Bancorp, Inc. 2017 Stock Option and Incentive Plan (the “Equity Plan”), the Company may grant options, restricted stock, restricted units or performance awards to its directors, officers and employees. Both incentive stock options and non-qualified stock options may be granted under the Equity Plan with 586,872 shares reserved for options. The exercise price of each option equals the market price of the Company’s stock on the date of the grant and the maximum term of each options is 10 years. The total number of shares reserved for restricted stock is 237,749. Options and awards generally vest ratably over three to five years. The fair value of shares awarded is based on the market price at the date of grant. Stock Options The fair value of each option grant is estimated on the date of the grant using the Black-Scholes option-pricing model with the following assumptions: • Volatility is based on peer group volatility because the Company does not have a sufficient trading history. • Expected life represents the period of time that the option is expected to be outstanding, taking into account the contractual term, and the vesting period. • Expected dividend yield is based on the Company's history and expectation of dividend payouts. • The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant for a period equivalent to the expected life of the option. The Company made the following grants of options to purchase shares of common stock during the years ended December 31, 2018 and 2017: 2018 2017 Options granted 27,000 340,387 Vesting period (years) 3-5 3-5 Expiration period (years) 10 10 Expected volatility 29.87 % 23.59% - 29.87% Expected life (years) 6.5 3.0 - 6.5 Expected dividend yield — — Risk free interest rate 2.68% - 2.77% 1.66% - 2.06% Option fair value $5.78 - $5.83 $2.71 - $5.05 A summary of the status of the Company's stock option grants for the year ended December 31, 2018 is presented in the table below: Options Stock Option Grants Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value Balance at January 1, 2018 316,009 $ 14.66 9.78 $ 219,374 Granted 27,000 16.15 5.79 — Forfeited (30,304 ) 14.71 6.50 — Balance at December 31, 2018 312,705 $ 14.78 8.73 $ — Exercisable at December 31, 2018 59,936 $ 14.66 — $ — Unrecognized compensation cost (inclusive of directors' options) $ 1,075,000 Weighted average remaining recognition period (years) 3.62 For the years ended December 31, 2018 and 2017, stock-based compensation expense applicable to stock options was $304,000 and $65,000, respectively. Restricted Stock Shares issued upon vesting may be either authorized but unissued shares or reacquired shares held by the Company. Any shares not issued because vesting requirements are not met will again be available for issuance under the plan. The fair market value of shares awarded, based on the market price at the date of grant, is recorded as unearned compensation and amortized over the applicable vesting period. Restricted stock awarded in 2017 was at no cost to the awardee. The following table presents the activity in restricted stock awards under the Equity Plan for the year ended December 31, 2018: Restricted Stock Awards Weighted Average Grant Price Restricted stock awards at January 1, 2018 176,239 $ 14.66 Granted — — Vested (33,835 ) 14.66 Forfeited (15,710 ) 14.66 Non-vested stock awards at December 31, 2018 126,694 $ 14.66 Unrecognized compensation cost $ 1,739,000 Weighted average remaining recognition period (years) 3.68 Total expense for the restricted stock awards was $493,000 and $120,000 for the years ended December 31, 2018 and 2017, respectively.

Employee Stock Ownership Plan

Employee Stock Ownership Plan	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Employee Stock Ownership Plan	1 3 . EMPLOYEE STOCK OWNERSHIP PLAN The Company maintains an Employee Stock Ownership Plan (“ESOP”), which is a tax-qualified retirement plan providing eligible employees the opportunity to own Bancorp stock. Bancorp granted a loan to the ESOP for the purchase of 469,498 shares of its common stock at $10.00 per share. The loan is payable annually over 25 years with interest at the prime rate to be reset each January 1 st Shares are committed to be released on a monthly basis and allocated as of December 31 st

Share Repurchase Program

Share Repurchase Program	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Share Repurchase Program	1 4 . SHARE REPURCHASE PROGRAM In September 2017, the Company’s Board of Directors adopted a share repurchase program under which the Company may repurchase up to 10%, or 586,854 shares of its then outstanding common shares. In September 2018, this program was extended for an additional year. Repurchases under the program may be made in open market or in privately negotiated transactions and pursuant to any trading plan that may be adopted in accordance with Rule 10b5-1 of the Securities and Exchange Commission. Any repurchased shares will be held by the Company as authorized but unissued shares. The repurchase program may be suspended or terminated at any time without prior notice and is currently set to expire on September 14, 2019. As of December 31, 2018, the Company had repurchased 117,877 shares at a cost of $1,832,000 in connection with this program.

Earnings (Loss) Per Share

Earnings (Loss) Per Share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Earnings (Loss) Per Share	15. EARNINGS (LOSS) PER SHARE Basic earnings (loss) per share represents net income (loss) divided by the weighted average of common shares outstanding during the period. Unvested restricted shares of common stock having dividend rights are treated as “participating securities” and, accordingly, are considered outstanding in computing basic earnings (loss) per share. Unallocated ESOP shares are not considered to be outstanding for purposes of computing earnings per share. None of the Company’s 312,705 outstanding stock options were included in the computation of diluted earnings (loss) per share for the years ended December 31, 2018 and 2017. Due to the net loss for these periods, inclusion of the stock options in the computation would have been anti-dilutive. The following table sets forth the calculation of the average number of shares outstanding used to calculate the basic and diluted earnings (loss) per share for the periods indicated: 2018 2017 Average number of common shares outstanding 5,994,373 5,902,981 Less: Average unallocated ESOP shares (423,653 ) (434,467 ) 5,570,720 5,468,514

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	1 6 . COMMITMENTS AND CONTINGENCIES In the normal course of business, there are outstanding commitments and contingencies which are not reflected in the accompanying consolidated financial statements. Lease commitments Pursuant to the terms of non-cancelable lease and sublease agreements in effect at December 31, 2018, future minimum rent commitments are as follows: Years Ending December 31, Leases Sub-lease Net (In thousands) 2019 $ 1,027 (87 ) $ 940 2020 919 (89 ) 830 2021 743 (91 ) 652 2022 545 (94 ) 451 2023 114 (16 ) 98 Thereafter — — — $ 3,348 $ (377 ) $ 2,971 The leases contain options to extend for periods of two to ten years. The cost of unexercised options periods is not included above. Total rent expense for the years ended December 31, 2018 and 2017 amounted to $992,000 and $883,000, respectively. Loan commitments The Company is a party to financial instruments with off-balance-sheet risk in the normal course of business to meet the financing needs of its customers. These financial instruments include commitments to extend credit. These instruments involve, to varying degrees, elements of market, credit and interest rate risk which are not recognized in the consolidated financial statements. The Company’s exposure to credit loss is represented by the contractual amount of these commitments. The Company uses the same credit policies in making commitments and conditional obligations as it does for on-balance-sheet instruments. At December 31, 2018 and 2017, the following financial instruments were outstanding whose contract amounts represent credit risk: 2018 2017 (In thousands) Commitments to originate loans $ 38,404 $ 35,549 Unused lines and letters of credit 45,977 39,968 Unadvanced funds on construction loans 14,175 6,967 Overdraft lines of credit 8,475 8,996 Commitments to extend credit are agreements to lend to a customer as long as there is no violation of any condition established in the contract. Commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. The commitments for lines of credit may expire without being drawn upon. Therefore, the total commitment amounts do not necessarily represent future cash requirements. The Company evaluates each customer’s creditworthiness on a case-by-case basis. The majority of these financial instruments are collateralized by real estate. Employment Arrangement and Change in Control Agreements The Company has entered into an employment arrangement with its President and Chief Executive Officer that provides for one year of salary continuation in the event his employment is terminated without cause or he resigns for good reason, subject to his providing a release of claims and complying with a non-solicitation and non-disclosure agreement. The Company has also entered into change in control agreements with five members of senior management which provide that if, within two years of a change of control of the Company or the Bank, the executive is involuntarily terminated other than for cause, disability or death, or voluntarily resigns for good reason, the executive will be entitled to a lump-sum payment equal to two times salary plus bonus. Other contingencies The Company is not currently a party to any pending legal proceedings that it believes would have a material adverse effect on its financial condition, results of operations or cash flows.

Fair Value of Assets and Liabil

Fair Value of Assets and Liabilities	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value of Assets and Liabilities	1 7 . 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. 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 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. . Total Level 1 Level 2 Level 3 Fair December 31, 2018 (In thousands) Assets: Securities available for sale: Debt securities $ — $ 50,038 $ — $ 50,038 Mutual fund — 518 — 518 Portfolio loans (fair value option) 3,680 — 3,680 Loans held for sale (fair value option) — 38,474 — 38,474 Derivative loan commitments — 627 — 627 Forward loan sale commitments — 10 — 10 Liabilities: Forward loan sale commitments, including TBAs — 263 — 263 December 31, 2017 Assets: Securities available for sale: Debt securities $ — $ 61,043 $ — $ 61,043 Mutual fund — 533 — 533 Loans held for sale (fair value option) — 25,390 — 25,390 Derivative loan commitments — 363 — 363 Forward loan sale commitments — 4 — 4 Liabilities: Forward loan sale commitments — 19 — 19 There were no transfers between levels for assets and liabilities recorded at fair value on a recurring basis during 2018 or 2017. Assets and liabilities measured at fair value on a non-recurring basis The Company may also be required, from time to time, to measure certain other assets 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 and liabilities. The following table summarizes the fair value hierarchy used to determine each adjustment and the carrying value of the related assets and liabilities as of December 31, 2018 and 2017. The gains and losses represent the amounts recorded during 2018 and 2017 on the assets and liabilities held at year-end. There no liabilities recorded at fair value on a non-recurring basis as of December 31, 2018 and 2017. Year Ended December 31, 2018 December 31, 2018 Level 1 Level 2 Level 3 Total Assets: (In thousands) Collateral dependent impaired loans $ — $ — $ 1,352 $ — Mortgage servicing rights — 7,786 — 82 Assets held for sale — — — 2,476 Foreclosed real estate — — 65 (36 ) $ — $ 7,786 $ 1,417 $ 2,522 Year Ended December 31, 2017 December 31, 2017 Level 1 Level 2 Level 3 Total Gains (Losses) (In thousands) Collateral dependent impaired loans $ — $ — $ 1,630 $ — Mortgage servicing rights — 6,397 — 334 Assets held for sale — — 828 (225 ) Foreclosed real estate — — 193 — $ — $ 6,397 $ 2,651 $ 109 Gains or losses applicable to impaired loans are based on the appraised value of the underlying collateral, discounted as necessary due to management’s estimates of charges in market conditions, less estimated selling costs, and are not recorded directly to current earnings but rather as a component in determining the allowance for loan losses. The Company utilizes an independent valuation from a third party which uses a discounted cash flow model to estimate the fair value of mortgage servicing rights. The model utilizes loan prepayment assumptions based on current market conditions and applies a discount rate based on indicated rates of return required by market participants. Prior to 2017 there were partial impairments in certain strata and, as a result, a valuation allowance was recorded. During the years ended December 31, 2018 and 2017, the fair value of these strata increased due to slower loan prepayment speeds and reductions in the discount rate from 14% at December 31, 2016 to 12% at December 31, 2018 resulting in partial reversals of $82,000 and $334,000 in the valuation allowance, respectively. During the year ended December 31, 2017, the Company recognized an impairment write-down of $225,000 upon transferring a branch location which was sold in 2018 to assets held for sale. The amount of the write-down is based on the terms of an executed purchase and sale agreement. During the year ended December 31, 2018, the Company sold three buildings which previously served as branch offices and recognized gains on sale of $2,476,000. See Note 5 for additional information. Summary of fair values of 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 mortgagor’s escrow accounts and accrued interest payable. December 31, 2018 Carrying Fair Amount Value Level 1 Level 2 Level 3 (In thousands) Financial assets: Certificates of deposit $ 2,205 $ 2,196 $ — $ 2,196 $ — Securities available for sale 50,556 50,556 — 50,556 — Loans held for sale 38,474 38,474 — 38,474 — Loans, net 483,846 473,612 — — 473,612 Derivative assets 637 637 — 637 — Financial liabilities: Deposits $ 437,130 $ 435,964 $ — $ 435,964 $ — FHLBB advances 89,036 88,894 — 88,894 — Derivative liabilities 263 263 — 263 — December 31, 2017 Carrying Fair Amount Value Level 1 Level 2 Level 3 (In thousands) Financial assets: Certificates of deposit $ 3,675 $ 3,687 $ — $ 3,687 $ — Securities available for sale 68,637 68,637 — 68,637 — Loans held for sale 30,452 30,452 — 30,452 — Loans, net 332,991 331,132 — — 331,132 Derivative assets 682 682 — 682 — Financial liabilities: Deposits $ 351,179 $ 350,979 $ — $ 350,979 $ — FHLBB advances 38,667 38,531 — 38,531 — Derivative liabilities 47 47 — 47 —

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Segment Information	18. SEGMENT INFORMATION Effective January 1, 2018, management began reporting its activities in one of two business segments, namely Envision Bank (“EB”) and Envision Mortgage (“EM”). Comparative information for the 2017 period has been prepared on a basis consistent with the methodology used in 2018. Envision Bank operations primarily consist of accepting deposits from customers within the communities surrounding the Bank’s five full service branch offices and investing those funds in residential and commercial real estate loans, home equity lines of credit, construction loans, commercial and industrial loans, and consumer loans. Envision Mortgage’s operations primarily consist of the origination and sale of residential mortgage loans and the servicing of loans sold to government-sponsored entities. A portion of the loans originated by Envision Mortgage are held in the loan portfolio of Envision Bank. Segment information as of and for the year ended December 31, 2018, follows: For the Year Ended December 31, 2018 Envision Bank Envision Mortgage Consolidated Total (in thousands) Net interest income $ 15,664 $ 1,032 $ 16,696 Provision for loan losses 762 — 762 Net interest income after provision for loan losses 14,902 1,032 15,934 Non-interest income: Customer service fees 1,344 120 1,464 Gain on loan origination and sale activities, net (1) — 8,859 8,859 Mortgage servicing fees, net (310 ) 1,574 1,264 Gain on sales of buildings 2,476 — 2,476 Other 520 420 940 Total non-interest income 4,030 10,973 15,003 Non-interest expenses: Salaries and employee benefits 6,793 12,972 19,765 Occupancy and equipment 1,507 1,366 2,873 Restructuring charges — 968 968 Other non-interest expenses 4,476 3,590 8,066 Total non-interest expenses 12,776 18,896 31,672 Income (loss) before income taxes and elimination of inter-segment profit $ 6,156 $ (6,891 ) (735 ) Elimination of inter-segment profit (1,320 ) Loss before income taxes (2,055 ) Income tax expense 31 Net loss $ (2,086 ) Total assets, December 31, 2018 $ 526,871 $ 87,469 $ 614,340 (1) Before elimination of inter-segment profit The information above was derived from the internal management reporting system used by management to measure performance of the segments. The Company’s internal transfer pricing arrangements determined by management primarily consist of the following: 1. EM’s cost of funds is based on the weighted average rate of overnight advances from the FHLBB for the period. 2. EM is credited with service released premiums and a sales premium totaling 1.50% for new loans transferred to EB’s loans held for investment, and a 1.00% fee for HELOC originations. This income for the year ended December 31, 2018 totaled $1,320,000. 3. Loan servicing fees are charged to EB by EM based on the number of residential mortgage loans held in portfolio at a rate of 0.14% per annum and amounted to $310,000 for the year ended December 31, 2018. 4. Certain cost centers provide services to both business segments. The cost centers include Accounting, Marketing, IT and Administration. Costs which are common to both business segments are referred to as “indirect costs” and are allocated using relevant benchmarks, e.g. headcount, number of accounts, etc. Segment information as of and for the year ended December 31, 2017 follows: For the Year Ended December 31, 2017 Envision Bank Envision Mortgage Consolidated Total (in thousands) Net interest income $ 13,827 $ 1,003 $ 14,830 Provision for loan losses 540 — 540 Net interest income after provision for loan losses 13,287 1,003 14,290 Non-interest income: Customer service fees 1,355 100 1,455 Gain on loan origination and sale activities, net (1) — 10,047 10,047 Mortgage servicing fees, net (258 ) 1,731 1,473 Other 408 476 884 Total non-interest income 1,505 12,354 13,859 Non-interest expenses: Salaries and employee benefits 6,243 12,488 18,731 Occupancy and equipment 1,392 1,263 2,655 Restructuring charges — 594 594 Merger and integration costs 19 512 531 Other non-interest expenses 3,955 3,356 7,311 Total non-interest expenses 11,609 18,213 29,822 Income (loss) before income taxes and elimination of inter-segment profit $ 3,183 $ (4,856 ) (1,673 ) Elimination of inter-segment profit (896 ) Loss before income taxes (2,569 ) Income tax benefit (443 ) Net loss $ (2,126 ) Total assets, December 31, 2017 $ 468,515 $ 63,377 $ 531,892 (1) Before elimination of inter-segment profit The information above was derived from the internal management reporting system used by management to measure performance of the segments. The Company’s internal transfer pricing arrangements determined by management primarily consist of the following: 1. EM’s cost of funds is based on the weighted average rate of overnight advances from the FHLBB for the period. 2. EM is credited with service released premiums and a sales premium totaling 1.50% for new loans transferred to EB’s loans held for investment, and a 1.00% fee for HELOC originations. This income for the year ended December 31, 2017 totaled $897,000. 3. Loan servicing fees are charged to EB by EM based on the number of residential mortgage loans held in portfolio at a rate of 0.14% per annum and amounted to $258,000 for the year ended December 31, 2017. 4. Certain cost centers provide services to both business segments. The cost centers include Accounting, Marketing, IT and Administration. Costs which are common to both business segments are referred to as “indirect costs” and are allocated using relevant benchmarks, e.g. headcount, number of accounts, etc.

Other Non-Interest Expenses

Other Non-Interest Expenses	12 Months Ended
	Dec. 31, 2018
Other Income And Expenses [Abstract]
Other Non-Interest Expenses	1 9 . OTHER NON-INTEREST EXPENSES Included in other non-interest expenses in 2018 and 2017 are certain items exceeding 1% of the Company’s total interest and non-interest income as follows: 2018 2017 (In thousands) Software amortization and maintenance $ 754 $ 789 Card related expenses 470 359 Data communication and telephone 495 463 Directors fees, including stock-based compensation 613 407

Restructuring Charges

Restructuring Charges	12 Months Ended
	Dec. 31, 2018
Restructuring And Related Activities [Abstract]
Restructuring Charges	20 . RESTRUCTURING CHARGES During the fourth quarter of 2017, the Company finalized a plan to reduce operating expenses through a workforce reduction in its mortgage banking operations to better align staffing levels with the then current volume of residential mortgage loan originations. The workforce reduction involved approximately 8% of the Company’s employees and took effect in 2017. The involuntary termination benefits accrued and charged to expense amounted to $594,000 and have been separately presented in the accompanying statement of operations for the year ended December 31, 2017. During the fourth quarter of 2018, the Company finalized a plan to consolidate mortgage banking operations in the Company’s North Attleboro loan operations center. As a result, the Company eliminated fifteen administrative positions supporting the origination of residential mortgages in its Andover loan operations center and added eight similar positions in its North Attleboro location. Approximately twenty-five employees, including loan originators, remain in the Andover location. Terminated employees were given a severance package based on their length of service with the Company. In addition, retention bonuses were offered to certain employees. The total cost of severance payments and retention bonuses amounted to $235,000 and is included in the restructuring charges in the accompanying statement of operations. As more fully disclosed in Note 5, the Company vacated all but approximately 4,200 square feet of its remaining lease space in Andover and recorded a cease use fair value liability of $565,000 which is included in the restructuring charge in the fourth quarter of 2018. In addition to the cease use liability, the Company also recognized an impairment write-down of $168,000 for furniture and equipment which is no longer expected to be used in operations. This write-down is also included in the restructuring charge recorded in the fourth quarter of 2018.

Parent Company Condensed Financ

Parent Company Condensed Financial Statements	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Parent Company Condensed Financial Statements	21 . PARENT COMPANY CONDENSED FINANCIAL STATEMENTS Financial information as of December 31, 2018 and 2017 and for the years then ended pertaining to Randolph Bancorp, Inc. is as follows: BALANCE SHEETS December 31, December 31, 2018 2017 Assets Cash and due from bank $ 6,850 $ 8,187 Due from Envision Bank — 141 Investment in Envision Bank 66,971 68,777 ESOP loan 4,266 4,378 Total assets $ 78,087 $ 81,483 Liabilities Accounts payable $ 70 $ — Due to Envision Bank 56 — 126 — Total liabilities Stockholders' Equity Common stock 60 61 Additional paid-in capital 55,608 56,493 Retained earnings 28,329 30,415 ESOP-Unearned compensation (4,132 ) (4,319 ) Accumulated other comprehensive loss, net of tax (1,904 ) (1,167 ) Total stockholders' equity 77,961 81,483 Total liabilities and stockholders' equity $ 78,087 $ 81,483 STATEMENTS OF OPERATIONS Years Ended December 31, 2018 2017 Interest income $ 197 $ 169 Operating expenses 197 308 Loss before incomes taxes and equity in undistributed net loss of Envision Bank — (139 ) Applicable income taxes — — Loss before equity in undistributed net loss of Envision Bank — (139 ) Equity in undistributed net loss of Envision Bank (2,086 ) (1,987 ) Net loss $ (2,086 ) $ (2,126 ) STATEMENTS OF CASH FLOWS Years Ended December 31, 2018 2017 Cash flows from operating activities: Net loss $ (2,086 ) $ (2,126 ) Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Equity in undistributed net loss of Envision Bank 2,086 1,987 Change in intercompany receivable/payable 197 (139 ) Net cash provided by (used in) operating activities 197 (278 ) Cash flows from investing activities: Payments received on ESOP loan 112 129 Net cash provided by investing activities 112 129 Cash flows from financing activities: Stock repurchases (1,716 ) (160 ) Stock repurchase payable 70 — Net cash used in financing activities (1,646 ) (160 ) Net change in cash and cash equivalents (1,337 ) (309 ) Cash and cash equivalents at the beginning of year 8,187 8,496 Cash and cash equivalents at end of year $ 6,850 $ 8,187

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (Unaudited)	22 . SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) First Quarter Second Quarter Third Quarter Fourth Quarter 2018 2017 2018 2017 2018 2017 2018 2017 (Dollars in thousands, except per share data) Interest and dividend income $ 4,727 $ 3,884 $ 5,039 $ 4,175 $ 5,468 $ 4,389 $ 6,050 $ 4,492 Interest expense 745 400 1,006 485 1,208 573 1,630 652 Net interest and dividend income 3,982 3,484 4,033 3,690 4,260 3,816 4,420 3,840 Provision (credit) for loan losses 95 235 (90 ) 100 178 — 579 205 Gain on loan origination and sales activities, net 1,547 2,038 1,854 2,520 1,956 2,705 2,183 1,888 Other non-interest income 861 1,372 929 914 1,252 866 3,102 660 Total non-interest income 2,408 3,410 2,783 3,434 3,208 3,571 5,285 2,548 Merger and integration costs — 167 — 357 — 7 — — Other non-interest expense 6,998 6,962 7,912 7,071 7,427 7,202 9,337 8,056 Total non-interest expense 6,998 7,129 7,912 7,428 7,427 7,209 9,337 8,056 Provision (benefit) for income taxes 4 (23 ) 4 (254 ) 5 129 17 (295 ) Net income (loss) $ (707 ) $ (447 ) $ (1,010 ) $ (150 ) $ (142 ) $ 49 $ (228 ) $ (1,578 ) Basic and diluted earnings (loss) per share $ (0.13 ) $ (0.08 ) $ (0.18 ) $ (0.03 ) $ (0.03 ) $ 0.01 $ (0.04 ) $ (0.28 ) Weighted average common shares (basic and diluted) 5,603,886 5,420,356 5,580,683 5,425,033 5,567,596 5,429,564 5,526,416 5,597,762 As disclosed in Note 20, the Company recognized restructuring charges in the fourth quarter of 2017 and 2018 associated with its mortgage banking operations. Included in other non-interest expense in the fourth quarter of 2018 and 2017 are $875,000 and $594,000, respectively, of expenses incurred in connection with such restructurings. As disclosed in Note 5, the Company recognized a gain of $2,261,000 on the sale of its former Boston branch location in the fourth quarter of 2018. The Company recognized an impairment write-down of $225,000 in the fourth quarter of 2017 on a branch office closed in 2018 and expenses of $160,000 associated with a planned transfer of loan servicing. Partially offsetting the impact of these expenses was a reduction of $200,000 in the valuation allowance for mortgage servicing rights due to an increase in their fair value. In connection with passage of the Tax Act in December 2017, the Company recognized a tax benefit of $462,000 due to repeal of the AMT in the fourth quarter of 2017.

Basis of Presentation and Sum_2

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The consolidated financial statements include the accounts of Randolph Bancorp, Inc. (a Massachusetts corporation) and its wholly-owned subsidiary, Envision Bank (together, the “Company”). The Bank has subsidiaries involved in owning investment securities and foreclosed real estate and a subsidiary which provides loan closing services. All intercompany accounts and transactions have been eliminated in consolidation.
Nature of Operations	Nature of Operations The Bank, which changed its name from Randolph Savings Bank to Envision Bank on March 12, 2018, provides a variety of financial services to individuals and small businesses through its five branch offices in Massachusetts. The Bank’s primary deposit products are checking, savings and term certificate accounts and its primary lending products are residential and commercial mortgage loans. The Bank is also actively involved in the sale and servicing of residential mortgage loans in the secondary market. The Federal Deposit Insurance Corporation (“FDIC”) provides insurance coverage on all deposits up to $250,000 per depositor. As an FDIC insured institution, the Bank is subject to supervision, examination and regulation by the FDIC. Additionally, as a Massachusetts chartered savings bank, the Bank’s depositors are also insured by the Depositors Insurance Fund (“DIF”), a private industry-sponsored insurance company. The DIF insures bank deposits in excess of the FDIC insurance limits. The following significant accounting and reporting policies of the Company conform to U.S. generally accepted accounting principles (“GAAP”) and are used in preparing and presenting these consolidated financial statements.
Use of Estimates	Use of estimates In preparing consolidated financial statements in conformity with GAAP, management is required to make estimates and assumptions that affect the reported amounts of assets and liabilities as of the date of the consolidated balance sheet and reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Material estimates that are particularly susceptible to significant change in the near term relate to the allowance for loan losses, mortgage servicing rights, deferred tax assets and fair value measurements.
Cash and Cash Equivalents	Cash and cash equivalents Cash equivalents include amounts due from banks, federal funds sold on a daily basis and interest-bearing deposits with original maturities of ninety days or less.
Certificates of Deposit	Certificates of deposit Certificates of deposit have original maturities ranging from one to five years and are carried at cost.
Fair Value Hierarchy	Fair value hierarchy The Company groups its assets and liabilities that are measured at fair value in three levels based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. Level 1 – Valuation is based on quoted prices in active markets for identical assets and liabilities. Valuations are obtained from readily available pricing sources. Level 2 – Valuation is based on observable inputs other than Level 1 prices, such as quoted prices for similar assets and liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets and liabilities. Level 3 – Valuation is based on unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets and liabilities. Level 3 assets and liabilities include those for which the value is determined using unobservable inputs to pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation. Transfers between levels are recognized at the end of a reporting period, if applicable.
Securities	Securities All securities are classified as available for sale and are recorded at fair value, with unrealized gains and losses excluded from earnings and reported in other comprehensive income/loss. Purchase premiums and discounts are recognized in interest income using the level yield method over the terms of the securities. Anticipated prepayments on mortgage-backed securities are used in applying this method. Gains and losses on the sale of securities are recorded on the trade date and are determined using the weighted average cost method for mutual funds and the specific identification method for other securities. On a quarterly basis, the Company evaluates all securities with a decline in fair value below the amortized cost of the investment to determine whether or not the impairment is deemed to be other than temporary (“OTTI”). OTTI is required to be recognized (1) if the Company intends to sell the security; (2) if it is “more likely than not” that the Company will be required to sell the security before recovery of its amortized cost basis; or (3) for debt securities, if the present value of expected cash flows is not sufficient to recover the entire amortized cost basis. For all impaired debt securities that the Company intends to sell, or more likely than not will be required to sell, the full amount of the decline in fair value is recognized as OTTI through earnings. For all other impaired debt securities, credit-related OTTI is recognized through earnings and non-credit related OTTI is recognized in other comprehensive income/loss, net of applicable taxes. Because the Company’s assessments are based on available factual information as well as subjective information, the determination as to whether an OTTI exists and, if so, the amount of impairment, is subjective and, therefore, the timing and amount of OTTI constitute material estimates that are subject to significant change.
Federal Home Loan Bank of Boston Stock	Federal Home Loan Bank of Boston stock The Bank, as a member of the Federal Home Loan Bank of Boston (“FHLBB”), is required to maintain an investment in capital stock of the FHLBB. Based on redemption provisions of the FHLBB, the stock has no quoted market value and is carried at cost. The Company periodically evaluates for impairment based on ultimate recovery of its cost basis in the FHLBB stock.
Loans Held for Sale and related derivatives	Loans held for sale and related derivatives The origination of residential mortgage loans is an integral part of the Company’s business. The Company generally sells its originations of such loans in the secondary market to either government-sponsored enterprises (“GSEs”) or other financial institutions. The servicing of loans sold to GSEs is initially retained while loans sold to other financial institutions are generally done on a servicing released basis. The Bank utilizes the fair value option pursuant to Accounting Standards Codification (“ASC”) 825, “Financial Instruments” for its residential mortgage loans being held for sale. Fair value is determined based on either commitments in effect from investors or prevailing market price and include the value of mortgage servicing rights. Gains and losses on the sales of loans are determined using the specific identification method. In determining the amount of the gain or loss the Company takes into consideration the direct costs of originating the loan. Also included in the net gain on loan origination and sale activities presented in the accompanying statements of operations are fair value adjustments for mortgage banking derivatives (interest rate lock commitments with borrowers, and forward loan sale commitments with investors for the delivery of mortgage loans to third party investors including To Be Announced securities (“TBAs”)) and loans held for sale.
Loans	Loans The Company grants residential real estate, commercial real estate, construction, commercial and consumer loans to customers. A substantial portion of the loan portfolio is represented by mortgage loans in eastern Massachusetts and Rhode Island. The ability of the Company’s borrowers to honor their contracts is affected by real estate values and general economic conditions in these markets. Loans that management has the intent and ability to hold for the foreseeable future or until maturity or pay-off are reported at their outstanding unpaid principal balances adjusted for charge-offs, the allowance for loan losses, and net deferred loan origination fees and costs and purchase premiums. Interest income is accrued on the unpaid principal balance. Certain direct loan origination costs and purchase premiums, net of origination fees, are deferred and recognized in interest income using the level yield method without anticipating prepayments. Interest is not accrued on loans which are ninety days or more past due, or when, in the judgment of management, the collectability of the principal or interest becomes doubtful. Past due status is based on contractual terms of the loan. Interest income previously accrued on such loans is reversed against current period earnings. Loans are returned to accrual status when all principal and interest amounts contractually due are brought current and future payments are reasonably assured.
Allowance for Loan Losses	Allowance for loan losses The allowance for loan losses is a valuation allowance for probable incurred credit losses. Loan losses are charged against the allowance when management believes the uncollectibility of a loan balance is confirmed. Subsequent recoveries, if any, are credited to the allowance. The allowance for loan losses is evaluated on a regular basis and is based upon management’s periodic review of the collectibility of the loans in light of historical experience, the nature and volume of the loan portfolio, adverse situations that may affect the borrower’s ability to repay, estimated value of any underlying collateral and prevailing economic conditions. This evaluation is inherently subjective as it requires estimates that are susceptible to significant revision as either additional information becomes available or circumstances change. The allowance for loan losses is allocated to loan types using both a formula-based approach applied to groups of loans (general component) and an analysis of certain individual loans for impairment (allocated component). General component The general component of the allowance for loan losses covers loans that are collectively evaluated for impairment and is based on historical loss experience adjusted for qualitative factors stratified by loan segments. Management uses a rolling average of historical losses based on a trailing 48 month time frame appropriate to capture relevant loss data for each loan segment. This historical loss factor is supplemented by the following qualitative factors: levels/trends in delinquencies; trends in volume and terms of loans; effects of changes in risk selection and underwriting standards and other changes in lending policies, procedures and practices; experience/ability/depth of lending management and staff; national and local economic trends and conditions, regulatory and legal factors; and risk rating concentrations. The qualitative factors are determined based on the various risk characteristics of each loan segment. Risk characteristics relevant to each portfolio segment are as follows: Residential one-to-four family real estate – The Company generally does not originate loans with a loan-to-value ratio greater than 80 percent. All loans in this segment are collateralized by one-to-four family owner, and non-owner-occupied, residential real estate and repayment is dependent on the credit quality of the individual borrower. The overall health of the economy, including unemployment rates and housing prices, will have an effect on the credit quality in this segment. Second mortgages and home equity lines of credit (HELOC) – Loans in this segment are primarily secured by second-position liens, and the Company may or may not also have a first-position lien. Regardless of which creditor is in first position, the Company does not originate loans with a combined loan-to-value ratio greater than 80 percent. All loans in this segment are collateralized by owner-occupied residential real estate and repayment is dependent on the credit quality of the individual borrower. The overall health of the economy, including unemployment rates and housing prices, will have an effect on the credit quality in this segment. Commercial real estate – Loans in this segment consist of owner-occupied and non-owner-occupied property throughout Massachusetts and Rhode Island. The underlying cash flows generated by the operating entities of owner-occupied real estate support the associated debt. Rental cash flows, for which management obtains periodic rent rolls, support the debt associated with non-owner-occupied real estate and can be negatively impacted by increased vacancy rates. Construction – Loans in this segment primarily include residential real estate development loans for which payment is derived from sale of the property. Credit risk is affected by cost overruns, time to sell at an adequate price, and market conditions. Commercial and Industrial – Loans in this segment are made to businesses and are generally secured by assets of the business. Repayment is expected from the cash flows of the business. A weakened economy, and resultant decreased consumer spending, would have an effect on the credit quality in this segment. Consumer – Loans in this segment primarily include personal unsecured loans, refinanced student loans and auto loans purchased from third party lenders. Repayment is dependent on the credit quality of the individual borrower. Allocated component The allocated component of the allowance for loan losses relates to loans that are individually classified as impaired. Residential real estate, commercial and industrial, commercial real estate and construction loans are evaluated for impairment on a loan-by-loan basis. Impairment is measured by either the present value of expected future cash flows discounted at the loan’s effective interest rate, or the fair value of the collateral if the loan is collateral dependent. An allowance is established when the discounted cash flows (or collateral value) of the impaired loan are lower than the carrying value of that loan. Large groups of smaller balance homogeneous loans are collectively evaluated for impairment. Accordingly, the Company does not generally identify individual consumer loans or second mortgages and HELOCs for impairment disclosures unless such loans are 90 days past due or are classified as a troubled debt restructuring. A loan is considered impaired when, based on current information and events, it is probable that the Company will be unable to collect the scheduled payments of principal or interest when due according to the contractual terms of the loan agreement. Factors considered by management in determining impairment include payment status, collateral value, and the probability of collecting scheduled principal and interest payments when due. Loans that experience insignificant payment delays and payment shortfalls generally are not classified as impaired. Management determines the significance of payment delays and payment shortfalls on a case-by-case basis, taking into consideration all of the circumstances surrounding the loan and the borrower, including the length of the delay, the reasons for the delay, the borrower’s prior payment record, and the amount of the shortfall in relation to the principal and interest owed. The Company periodically may agree to modify the contractual terms of loans. When a loan is modified and a concession is made to a borrower experiencing financial difficulty, the modification is considered a troubled debt restructuring (“TDR”). All TDRs are classified as impaired.
Bank-owned Life Insurance	Bank-owned life insurance Bank-owned life insurance policies are reflected on the consolidated balance sheets at their cash surrender value net of charges or other amounts that are probable at settlement. Changes in the net cash surrender value of the policies, as well as insurance proceeds received, are reflected in non-interest income in the consolidated statements of operations and are not subject to income taxes, unless such policies are surrendered prior to the death of the insured individuals.
Mortgage Servicing Rights	Mortgage servicing rights The Company services mortgage loans for others. Mortgage servicing rights are recognized as separate assets at fair value when rights are acquired through purchase or through sale of financial assets. Capitalized servicing rights are amortized into mortgage servicing income in proportion to, and over the period of, the estimated future net servicing income of the underlying financial assets. Servicing rights are evaluated for impairment based upon the fair value of the rights as compared to amortized cost. Impairment is determined by stratifying rights by predominant risk characteristics, such as interest rates and terms. Fair value is based on a valuation model that calculates the present value of estimated future net servicing income, using market-based assumptions. Impairment is recognized through a valuation allowance for an individual stratum, to the extent that fair value is less than the capitalized amount for the stratum. Changes in the valuation allowance, if any, are reported in mortgage servicing income.
Premises and Equipment	Premises and equipment Land is carried at cost. Buildings, equipment and leasehold improvements are stated at cost, less accumulated depreciation and amortization computed on the straight-line method over the estimated useful lives of the assets or the expected terms of the leases, if shorter. Expected terms include lease option periods to the extent that the exercise of such options is reasonably assured. Premises and equipment held for sale are stated at the lower of amortized cost or fair value less costs to sell.
Transfers of Financial Assets	Transfers of financial assets Transfers of financial assets are accounted for as sales when control over the assets has been surrendered. Control over transferred assets is deemed to be surrendered when (1) the assets have been isolated from the Company, (2) the transferee obtains the right to pledge or exchange the transferred assets, and (3) the Company does not maintain effective control over the transferred assets through an agreement to repurchase them before their maturity. During the normal course of business, the Company may transfer a portion of a financial asset, for example, a participation loan. In order to be eligible for sales treatment, all cash flows from the loan must be divided proportionately, the rights of each loan holder must have the same priority, the loan holders must have no recourse to the transferor other than standard representations and warranties, and no loan holder can have the right to pledge or exchange the entire loan. In certain cases, the Company may have an obligation to repurchase mortgage loans sold to third parties and to refund fees to the purchaser if a payment default or prepayment occurs, in each case within a prescribed time period not exceeding four months after the sale date, or in the case of a violation of its representations and warranties under the provisions of its loan sale agreements. The Company evaluates its obligations under these provisions and recognizes a liability for the fair value of its recourse obligations. At December 31, 2018 and 2017, the Company determined that its obligations in connection with the recourse provisions of its loan sale agreements were insignificant.
Foreclosed Real Estate	Foreclosed real estate Real estate acquired through, or in lieu of, loan foreclosure are held for sale and are initially recorded at fair value, less costs to sell, at the date of foreclosure, establishing a new cost basis. Subsequent to foreclosure, valuations are periodically performed by management and the assets are carried at the lower of carrying amount or fair value less costs to sell. Revenue and expenses from operations, changes in the valuation allowance and any direct write-downs are included in foreclosed real estate expense.
Supplemental Retirement Plans	Supplemental retirement plan The Company accounts for its supplemental retirement plan using an actuarial model that allocates cost over the service period of participants in the plan. The Company accounts for the over-funded or under-funded status of the plan as an asset or liability in its consolidated balance sheets and recognizes changes in the funded status in the year in which the changes occur through other comprehensive income/loss.
Employee Stock Ownership Plan	Employee Stock Ownership Plan Compensation expense for the Employee Stock Ownership Plan (“ESOP”) is computed based on the number of shares allocated to participants during the period multiplied by the average fair market value of the Company’s shares. This expense is recognized ratably throughout the year based on the expected allocation of shares for the year. Unearned compensation applicable to the ESOP is reflected as a reduction of stockholders’ equity. The difference between the average fair market value and cost of the shares allocated by the ESOP is recorded as an adjustment to additional paid-in capital.
Stock-Based Compensation	Stock-based Compensation The fair value of restricted stock and stock options is determined on the date of grant and amortized to compensation expense with a corresponding increase to additional paid-in capital over the required service period, but in no event beyond the date of an employee’s or director’s date of termination. Forfeitures of unvested awards and grants are recorded as incurred.
Advertising Costs	Advertising costs Advertising costs are expensed as incurred.
Income Taxes	Income taxes Deferred income tax assets and liabilities are determined using the liability (or balance sheet) method. Under this method, the net deferred tax asset or liability is determined based on the tax effects of the temporary differences between the book and tax basis of the various balance sheet assets and liabilities and gives current recognition to changes in tax rates and laws. A valuation allowance is established against deferred tax assets when, based upon available evidence including historical and projected taxable income, that some or all of the deferred tax assets will not be realized. A tax position is recognized as a benefit if it is “more likely than not” that the tax position would be sustained in a tax examination, with a tax examination being presumed to occur. The amount recognized is the largest amount of tax benefit greater than 50% likely of being realized on examination. For tax positions not meeting the “more likely than not” test, no tax benefit is recorded. The Company does not have any uncertain tax positions at December 31, 2018 and 2017 which require accrual or disclosure. The Company records interest and penalties as part of income tax expense. No interest or penalties were recorded for the years ended December 31, 2018 and 2017.
Comprehensive Income (Loss)	Comprehensive income (loss) 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 equity, such items, along with net income (loss), are components of comprehensive income (loss). The components of accumulated other comprehensive loss (“AOCI”), included in stockholders’ equity, are as follows: December 31, December 31, 2018 2017 (In thousands) Securities available for sale: Net unrealized loss $ (1,334 ) $ (624 ) Tax effect (313 ) (313 ) Net-of-tax amount (1,647 ) (937 ) Supplemental retirement plan Unrecognized net actuarial loss (605 ) (667 ) Unrecognized net prior service credit 395 484 (210 ) (183 ) Tax effect (47 ) (47 ) Net-of-tax amount (257 ) (230 ) Accumulated other comprehensive loss $ (1,904 ) $ (1,167 ) In 2019, the Company expects to recognize $89,000 in prior service credits and $41,000 in net actuarial losses as components of cost for the supplemental retirement plan. These amounts are included in accumulated other comprehensive loss at December 31, 2018. Prior service credits and net actuarial gains and losses are amortized to periodic pension cost over varying periods based on the plan participants to whom they relate.
Segment Reporting	Segment reporting Prior to 2018, the Company’s operations were managed, and financial performance was evaluated, by the chief operating decision-maker on a company-wide basis. As a result, management had determined there to be a single business segment for financial reporting purposes through December 31, 2017. Due to the significance of the Company’s mortgage banking operations and the strategic focus on this business, management prepared its 2018 operating budget by breaking-out its mortgage banking activities, including residential loan origination and loan servicing. As a result, effective January 1, 2018, the Company is reporting two business segments, namely, “Envision Bank” and “Envision Mortgage”. Comparative information for 2017 has been prepared on a basis consistent with the methodology used in 2018. As part of this process, management analyzed costs incurred by departments providing services to both segments (indirect costs), such as IT, Marketing, Accounting and Administration, to determine the allocation of indirect costs to each business segment in order to fully measure each segment’s results of operations. See Note 18 for disclosure of the Company’s segment information.
Earnings (Loss) Per Share	Earnings (Loss) Per Share Basic earnings (loss) per share represents income (loss) available to common stockholders divided by the weighted average of common shares outstanding during the period. Unvested restricted shares of common stock having dividend rights are treated as “participating securities” and, accordingly, are considered outstanding in computing basic earnings (loss) per share. Unallocated ESOP shares are not considered outstanding in computing earnings (loss) per share. Diluted earnings per share reflects additional common shares that would have been outstanding if dilutive potential shares had been issued. Stock options represent potential dilutive shares with the number of such shares computed using the treasury method. No potential dilutive shares were considered in the computation of loss per share in 2018 and 2017 as the impact would be anti-dilutive.
Business Combinations	Business combinations We account for business combinations under the acquisition method of accounting. The application of this method of accounting requires the use of significant estimates and assumptions in the determination of the fair value of tangible and identified intangible assets acquired and liabilities assumed in order to properly allocate purchase price consideration between assets from those that are recorded as goodwill. Our estimates of the fair values of assets acquired and liabilities assumed are based upon assumptions that we believe to be reasonable, and whenever necessary, include assistance from independent third-party appraisal and valuation firms. Costs incurred to consummate a business combination are expensed as incurred.
Recent Accounting Pronouncements	Recent accounting pronouncements In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers . This Update provides a revenue recognition framework for any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of non-financial assets unless those contracts are within the scope of other accounting standards. This ASU, as amended by ASU 2015-14, is effective for emerging growth companies in fiscal years beginning after December 15, 2018, including interim periods therein with early adoption permitted. The timing of the Company’s revenue recognition is not expected to materially change. The Company's revenue relates principally to financial instruments, which are explicitly excluded from the scope of the new guidance. Adoption of this standard on January 1, 2019 did not have a material impact on the Company’s consolidated financial statements. In January 2016, FASB issued ASU 2016-01, Financial Instruments In February 2016, FASB issued ASU 2016-02, Leases In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses In April 2017, the FASB issued ASU 2017-08 Receivables – Non-refundable Fees and Other Costs In August 2018, the FASB issued ASU 2018-13 Fair Value Measurement – Changes to the Disclosure Requirements for Fair Value Measurement,
Reclassifications	Reclassifications Certain reclassifications have been made to the 2017 consolidated financial statements in order to conform to the presentations used in the 2018 consolidated financial statements. Such reclassifications had no impact on net loss as presented in such financial statements .

Basis of Presentation and Sum_3

Basis of Presentation and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Components of Accumulated Other Comprehensive Loss (AOCI) and Related Tax Effects	The components of accumulated other comprehensive loss (“AOCI”), included in stockholders’ equity, are as follows: December 31, December 31, 2018 2017 (In thousands) Securities available for sale: Net unrealized loss $ (1,334 ) $ (624 ) Tax effect (313 ) (313 ) Net-of-tax amount (1,647 ) (937 ) Supplemental retirement plan Unrecognized net actuarial loss (605 ) (667 ) Unrecognized net prior service credit 395 484 (210 ) (183 ) Tax effect (47 ) (47 ) Net-of-tax amount (257 ) (230 ) Accumulated other comprehensive loss $ (1,904 ) $ (1,167 )

Securities Available for Sale (

Securities Available for Sale (Tables)	12 Months Ended
	Dec. 31, 2018
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) December 31, 2018 Debt securities: U.S. Government-sponsored enterprises $ 3,999 $ 13 $ (31 ) $ 3,981 Corporate 1,524 6 (18 ) 1,512 Municipal 1,489 18 — 1,507 Residential mortgage-backed securities: U.S. Government-sponsored enterprises 26,989 71 (754 ) 26,306 Commercial mortgage-backed securities: U.S. Government-sponsored enterprises 9,094 — (487 ) 8,607 U.S. Government-guaranteed 1,796 — (33 ) 1,763 Collateralized mortgage obligations: U.S. Government-sponsored enterprises 1,642 — (17 ) 1,625 U.S. Government-guaranteed 4,839 2 (104 ) 4,737 Total debt securities 51,372 110 (1,444 ) 50,038 Mutual fund 518 — — 518 Total securities available for sale $ 51,890 $ 110 $ (1,444 ) $ 50,556 December 31, 2017 Debt securities: U.S. Government-sponsored enterprises $ 3,999 $ 50 $ (24 ) $ 4,025 Corporate 2,005 27 (8 ) 2,024 Municipal 12,707 179 (18 ) 12,868 Residential mortgage-backed securities: U.S. Government-sponsored enterprises 18,729 118 (450 ) 18,397 Commercial mortgage-backed securities: U.S. Government-sponsored enterprises 14,451 13 (403 ) 14,061 U.S. Government-guaranteed 2,132 — (6 ) 2,126 Collateralized mortgage obligations: U.S. Government-sponsored enterprises 1,871 12 (5 ) 1,878 U.S. Government-guaranteed 5,760 4 (100 ) 5,664 Total debt securities 61,654 403 (1,014 ) 61,043 Mutual fund 545 — (12 ) 533 Total securities available for sale $ 62,199 $ 403 $ (1,026 ) $ 61,576
Investments Classified by Contractual Maturity Date	The amortized cost and fair value of debt securities by contractual maturity at December 31, 2018 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 6,173 6,149 After 5 years through 10 years 839 851 7,012 7,000 Mortgage-backed securities and collaterlized mortgage obligations 44,360 43,038 $ 51,372 $ 50,038
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 December 31, 2018 (In thousands) Debt securities: U.S. Government-sponsored enterprises $ — $ — $ (31 ) $ 1,969 Corporate (5 ) 497 (13 ) 506 Municipal — — — — Residential mortgage-backed securities: U.S. Government-sponsored enterprises (6 ) 7,038 (748 ) 12,981 Commercial mortgage-backed securities: U.S. Government-sponsored enterprises — — (487 ) 8,607 U.S. Government-guaranteed — — (33 ) 1,763 Collateralized mortgage obligations: U.S. Government-sponsored enterprises — — (17 ) 1,625 U.S. Government-guaranteed — — (104 ) 3,879 Total debt securities $ (11 ) $ 7,535 $ (1,433 ) $ 31,330 December 31, 2017 Debt securities: U.S. Government-sponsored enterprises $ — $ — $ (24 ) $ 19,676 Corporate — — (8 ) 988 Municipal (11 ) 1,919 (7 ) 479 Residential mortgage-backed securities: U.S. Government-sponsored enterprises (1 ) 1,623 (449 ) 13,163 Commercial mortgage-backed securities: U.S. Government-sponsored enterprises — — (403 ) 8,805 U.S. Government-guaranteed (6 ) 2,126 — — Collateralized mortgage obligations: U.S. Government-sponsored enterprises (5 ) 678 — — U.S. Government-guaranteed (1 ) 295 (99 ) 3,756 Total debt securities (24 ) 6,641 (990 ) 46,867 Mutual fund — — (12 ) 533 $ (24 ) $ 6,641 $ (1,002 ) $ 47,400

Loans (Tables)

Loans (Tables)	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Summary of Loan Portfolio	A summary of the loan portfolio is as follows: December 31, 2018 2017 (In thousands) Mortgage loans on real estate: Residential: One-to-four family $ 246,756 $ 198,475 Home equity loans and lines of credit 43,545 38,968 Commercial 113,642 98,755 Construction 42,139 25,357 446,082 361,555 Commercial and industrial 21,285 24,766 Consumer 19,407 16,337 Total loans 486,774 402,658 Allowance for loan losses (4,437 ) (3,737 ) Net deferred loan costs and fees, and purchase premiums 1,509 1,452 $ 483,846 $ 400,373
Summary of Activity in the Allowance for Loan Losses by Loan Category	The following table presents activity in the allowance for loan losses, by loan category, for the years ended December 31, 2018 and 2017 and allocation of the allowance to each category as of such dates: Second Residential Mortgages Commercial Commercial 1-4 Family and HELOC Real Estate Construction and Industrial Consumer Total (In thousands) Allowance for loan losses Balance at December 31, 2016 $ 1,018 $ 436 $ 1,410 $ 225 $ 37 $ 145 $ 3,271 Provision (credit) for loan losses (187 ) (77 ) 210 126 263 205 540 Loans charged-off — — — — — (153 ) (153 ) Recoveries 23 — — — 35 21 79 Balance at December 31, 2017 854 359 1,620 351 335 218 3,737 Provision (credit) for loan losses 197 (67 ) 30 414 (70 ) 258 762 Loans charged-off — — (2 ) — — (119 ) (121 ) Recoveries 41 — — — — 18 59 Balance at December 31, 2018 $ 1,092 $ 292 $ 1,648 $ 765 $ 265 $ 375 $ 4,437
Summary of Additional Information Pertaining to the Allowance for Loan Losses	Second Residential Mortgages Commercial Commercial 1-4 Family and HELOC Real Estate Construction and Industrial Consumer Total December 31, 2018 Allowance for impaired loans $ 108 $ — $ — $ — $ — $ 174 $ 282 Allowance for non-impaired loans 984 292 1,648 765 265 201 4,155 Total allowance for loan losses $ 1,092 $ 292 $ 1,648 $ 765 $ 265 $ 375 $ 4,437 Impaired loans $ 6,291 $ 408 $ 52 $ — $ — $ 199 $ 6,950 Non-impaired loans 240,465 43,137 113,590 42,139 21,285 19,208 479,824 Total loans $ 246,756 $ 43,545 $ 113,642 $ 42,139 $ 21,285 $ 19,407 $ 486,774 December 31, 2017 Allowance for impaired loans $ 160 $ 1 $ 1 $ — $ — $ — $ 162 Allowance for non-impaired loans 694 358 1,619 351 335 218 3,575 Total allowance for loan losses $ 854 $ 359 $ 1,620 $ 351 $ 335 $ 218 $ 3,737 Impaired loans $ 5,205 $ 276 $ 352 $ — $ — $ — $ 5,833 Non-impaired loans 193,270 38,692 98,403 25,357 24,766 16,337 396,825 Total loans $ 198,475 $ 38,968 $ 98,755 $ 25,357 $ 24,766 $ 16,337 $ 402,658
Schedule of Past Due and Non-Accrual Loans by Loan Category	The following table presents past due and non-accrual loans, by loan category, at December 31, 2018 and 2017: 30 - 59 Days Past Due 60 - 89 Days Past Due 90 Days or More Past Due Total Past Due Non-accrual Loans (In thousands) December 31, 2018 Residential one-to-four family $ 655 $ 207 $ 635 $ 1,497 $ 2,474 Home equity loans and lines of credit 520 — — 520 407 Commercial real estate — — — — — Construction — — — — — Commercial and industrial — — — — — Consumer 25 4 — 29 149 Total $ 1,200 $ 211 $ 635 $ 2,046 $ 3,030 December 31, 2017 Residential one-to-four family $ 737 $ — $ — $ 737 $ 1,975 Home equity loans and lines of credit 96 — — 96 276 Commercial real estate — — — — — Construction — — — — — Commercial and industrial — — — — — Consumer — — — — — Total $ 833 $ — $ — $ 833 $ 2,251
Summary of Impaired Loans and Information Related to Average Balances of Impaired Loans and Interest Income Recognized	Further information pertaining to impaired loans, which includes both non-accrual loans and troubled debt restructurings, follows: Recorded Investment Unpaid Principal Balance Related Allowance (In thousands) December 31, 2018 Impaired loans without a valuation allowance: Residential one-to-four family $ 4,280 $ 4,280 $ — Home equity loans and lines of credit 408 408 — Commercial real estate 52 52 — Total 4,740 4,740 — Impaired loans with a valuation allowance: Residential one-to-four family 2,011 2,011 108 Consumer 199 199 174 Total 2,210 2,210 282 Total impaired loans $ 6,950 $ 6,950 $ 282 December 31, 2017 Impaired loans without a valuation allowance: Residential one-to-four family $ 2,641 $ 2,641 $ — Home equity loans and lines of credit 247 247 — Commercial real estate 257 257 — Total 3,145 3,145 — Impaired loans with a valuation allowance: Residential one-to-four family 2,564 2,564 160 Home equity loans and lines of credit 29 29 1 Commercial real estate 95 95 1 Total 2,688 2,688 162 Total impaired loans $ 5,833 $ 5,833 $ 162 Information related to the average balances of impaired loans and the interest income recognized on such loans, follows: Average Interest Cash Basis Recorded Income Interest Investment Recognized Recognized (In thousands) Year Ended December 31, 2018 Residential one-to-four family $ 6,781 $ 210 $ 84 Home equity loans and lines of credit 420 36 36 Commercial real estate 244 15 — Consumer 50 2 — Total $ 7,495 $ 263 $ 120 Year Ended December 31, 2017 Residential one-to-four family $ 4,956 $ 195 $ 82 Home equity loans and lines of credit 276 1 1 Commercial real estate 655 36 — Total $ 5,887 $ 232 $ 83
Summary of Company's Loans by Risk Rating	The following table presents the Company’s loans by risk rating at December 31, 2018 and 2017: December 31, 2018 December 31, 2017 Commercial Real Construction Commercial and Industrial Commercial Real Construction Commercial and Industrial (In thousands) Loans rated 1 - 3A $ 113,642 $ 42,139 $ 21,285 $ 98,556 $ 25,357 $ 24,766 Loans rated 4 — — — — — — Loans rated 5 — — — 199 — — $ 113,642 $ 42,139 $ 21,285 $ 98,755 $ 25,357 $ 24,766

Loan Servicing (Tables)

Loan Servicing (Tables)	12 Months Ended
	Dec. 31, 2018
Transfers And Servicing [Abstract]
Summary of Activity In Company's Mortgage Servicing Rights	The following table summarizes the activity in the Company’s mortgage servicing rights for the indicated periods: For the Year Ended December 31, 2018 2017 Mortgage servicing rights: (In thousands) Balance at beginning of year $ 6,397 $ 8,486 Additions through originations 2,380 2,310 Amortization (983 ) (1,071 ) Sales — (3,238 ) Balance at end of year $ 7,794 $ 6,487 Valuation allowance: Balance at beginning of year $ 90 $ 424 Provision (credit) (82 ) (334 ) Balance at end of year $ 8 $ 90 Mortgage servicing rights, amortized cost $ 7,786 $ 6,397 Mortgage servicing rights, fair value $ 8,554 $ 6,485

Premises and Equipment (Tables)

Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Summary of Cost and Accumulated Depreciation and Amortization of Premises and Equipment	A summary of the cost and accumulated depreciation and amortization of premises and equipment is as follows: December 31, Estimated 2018 2017 Useful Life (In thousands) (In years) Land and improvements $ 1,025 $ 2,525 Buildings and improvements 3,280 4,457 5 to 50 Leasehold improvements 2,136 1,503 3 to 10 Furniture and equipment 5,032 4,765 3 to 10 Construction-in-progress 84 101 11,557 13,351 Less accumulated depreciation and amortization (5,189 ) (4,681 ) $ 6,368 $ 8,670

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2018
Deposits [Abstract]
Summary of Deposit Balances by Type	A summary of deposit balances, by type, is as follows: December 31, 2018 2017 (In thousands) Demand deposits $ 64,229 $ 62,130 NOW accounts 42,802 44,988 Money market deposits 60,843 56,668 Regular and other savings 101,137 102,528 Brokered deposits 10,088 7,106 Total non-certificate accounts 279,099 273,420 Term certificates less than $250,000 99,491 80,538 Term certificates of $250,000 or more 8,048 12,878 Term certificates - brokered 50,492 — Total certificate accounts 158,031 93,416 $ 437,130 $ 366,836
Summary of Term Certificates, Including Brokered Deposits, by Maturity	A summary of term certificates, including brokered deposits, by maturity is as follows: December 31, 2018 December 31, 2017 Weighted Weighted Average Average Maturing during: Amount Rate Amount Rate (Dollars in thousands) 2018 $ — — % 49,550 0.84 % 2019 89,167 1.68 22,470 1.20 2020 40,847 2.16 8,754 1.44 2021 12,785 2.16 4,873 1.57 2022 14,101 1.98 7,769 1.65 2023 1,131 1.38 — — $ 158,031 1.87 % $ 93,416 1.09 %

Borrowings (Tables)

Borrowings (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Summary of Borrowings from FHLBB	A summary of borrowings from the FHLBB at December 31, 2018 and 2017 is as follows: 2018 2017 Weighted Weighted Average Average Amount Rate Amount Rate (Dollars in thousands) Fixed-rate advances maturing: 2018 $ — — % $ 69,337 1.55 % 2019* 84,184 2.57 1,500 1.00 2020* 2,894 1.49 3,129 1.52 2021* 1,958 1.33 1,988 1.34 $ 89,036 2.50 % $ 75,954 1.54 % * Includes amortizing advances which require monthly principal and interest payments.
Summary of Outstanding Balances of Short Term Borrowings from FHLBB	Included in FHLBB borrowings at December 31, 2018 and 2017 are overnight advances and advances having a one-month maturity of $82.7 million and $64.7 million, respectively. Selected information for such short-term borrowings for the years presented is as follows (in 000’s): 2018 2017 Average daily balance $ 63,552 $ 34,656 Maximum outstanding at any month end 108,819 64,739

Income Taxes (Table)

Income Taxes (Table)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Allocation of Federal and State Income Taxes Between Current and Deferred Portions	Allocation of federal and state income taxes between current and deferred portions is as follows (in thousands): Years Ended December 31, 2018 2017 Current tax expense (benefit): Federal $ — $ (462 ) State 31 19 Total current tax expense (benefit) 31 (443 ) Deferred tax expense (benefit): Federal (541 ) (518 ) Effect of change in federal tax rate — 1,627 State 73 (23 ) (468 ) 1,086 Change in valuation allowance 468 541 Effect of change in federal tax rate - valuation allowance — (1,627 ) Total deferred tax expense — — Total tax expense (benefit) $ 31 $ (443 )
Summary of Differences Between Statutory Federal Income Tax Expense (Benefit) and Actual Tax Expense (Benefit)	The reasons for the differences between the statutory federal income tax expense (benefit) and the actual tax expense (benefit) are summarized as follows (in thousands): Years Ended December 31, 2018 2017 Statutory federal tax (21% in 2018 and 34% in 2017) $ (432 ) $ (874 ) Increase (decrease) resulting from: State taxes, net of federal tax effect 83 (3 ) Bank-owned life insurance (46 ) (52 ) Tax exempt income (25 ) (118 ) Dividends received deduction — (5 ) Change in valuation allowance 468 541 Change in AOCI deferred effect — (36 ) Effect of change in federal tax rate — 1,627 Effect of change in federal tax rate-valuation allowance — (1,627 ) Other, net (17 ) 104 Total tax expense (benefit) $ 31 $ (443 )
Summary of Components of Net Deferred Tax Asset	The components of the net deferred tax asset are as follows (in thousands): December 31, 2018 2017 Deferred tax assets: Federal $ 5,134 $ 4,247 State 1,134 1,008 6,268 5,255 Valuation allowance (3,246 ) (2,778 ) 3,022 2,477 Deferred tax liabilities: Federal (2,189 ) (1,806 ) State (833 ) (671 ) (3,022 ) (2,477 ) Net deferred tax asset $ — $ —
Summary of Deferred Tax Asset (Liabilities)	The tax effects of items giving rise to deferred tax assets (liabilities) are as follows (in thousands): December 31, 2018 2017 Employee benefit plans $ 825 $ 951 Allowance for loan losses 1,247 1,050 Funded status of post-retirement benefits (47 ) (47 ) Securities available for sale (313 ) (313 ) Depreciation and amortization 249 193 Net deferred loan origination costs (357 ) (321 ) Mortgage servicing rights (2,082 ) (1,624 ) Net operating loss carryforward 2,864 2,171 Charitable contribution carryforward 700 702 Derivatives (105 ) (98 ) Stock-based compensation 121 48 Other, net 144 66 3,246 2,778 Valuation allowance on deferred tax assets (3,246 ) (2,778 ) Net deferred tax asset $ — $ —

Minimum Regulatory Capital Re_2

Minimum Regulatory Capital Requirements (Tables)	12 Months Ended
	Dec. 31, 2018
Banking And Thrift [Abstract]
Summary of Actual and Minimum Capital Amounts and Ratios	The Bank’s actual and minimum capital amounts and ratios are presented in the following table: Minimum To Be Well For Minimum Capitalized Under Capital Prompt Corrective Actual Adequacy Purposes Action Provisions Amount Ratio Amount Ratio Amount Ratio (Dollars in thousands) December 31, 2018 Total capital (to risk weighted assets) $ 72,523 16.1 % $ 36,084 8.0 % $ 45,105 10.0 % Tier 1 capital (to risk weighted assets) 68,086 15.1 27,063 6.0 36,084 8.0 Common equity Tier 1 capital (to risk weighted assets) 68,086 15.1 20,297 4.5 29,318 6.5 Tier 1 capital (to average assets) 68,086 10.9 25,056 4.0 31,320 5.0 December 31, 2017 Total capital (to risk weighted assets) 73,612 20.4 28,896 8.0 36,120 10.0 Tier 1 capital (to risk weighted assets) 69,875 19.4 21,667 6.0 28,889 8.0 Common equity Tier 1 capital (to risk weighted assets) 69,875 19.4 16,250 4.5 23,472 6.5 Tier 1 capital (to average assets) 69,875 12.4 22,564 4.0 28,205 5.0

Post-retirement Plans (Tables)

Post-retirement Plans (Tables)	12 Months Ended
	Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Summary of Information Pertaining to Activity in Plan	The Company has a master supplemental retirement plan (“Plan”) which covers certain officers and directors of the Company. In 2018 and 2017, the only active participants in the Plan were directors. Information pertaining to activity in the Plan follows: Years Ended December 31, 2018 2017 (In thousands) Change in plan assets: Fair value of plan assets at beginning of year $ — $ — Employer contributions 201 201 Benefits paid (201 ) (201 ) Fair value of plan assets at end of year — — Change in benefit obligation: Benefit obligation at beginning of year 1,724 1,836 Service cost 10 10 Interest cost 48 53 Actuarial (gain) loss (20 ) 26 Benefits paid (201 ) (201 ) Benefit obligation at end of year 1,561 1,724 Unfunded status and accrued supplemental pension cost at year end $ (1,561 ) $ (1,724 ) Accumulated benefit obligation at year end $ 1,561 $ 1,724
Summary of Assumptions Used to Determine Benefit Obligation	The assumptions used to determine the benefit obligation are as follows: December 31, 2018 2017 Discount rate 3.60 % 2.90 % Annual inflation factor 1.00 % 1.00 % The following assumptions were used to determine the net periodic benefit cost for the years ended December 31, 2018 and 2017: 2018 2017 Discount rate 2.90 % 3.05 % Annual inflation factor 1.00 % 1.00 %
Summary of Net Periodic Benefit Cost Included in Salaries and Employee Benefits Expense	Net periodic benefit cost, included in other non-interest expenses, attributable to the Plan for the years ended December 31, 2018 and 2017, consists of the following: 2018 2017 (In thousands) Service cost $ 10 $ 10 Interest cost 48 53 Amortization of net actuarial loss 41 38 Amortization of prior service credit (89 ) (89 ) $ 10 $ 12
Summary of Estimated Future Benefit Payments Expected Future Services	Estimated future benefit payments, which reflect expected future services, as appropriate, are as follows: Years Ending December 31, Amount (In thousands) 2019 $ 201 2020 201 2021 201 2022 213 2023 334 2024-2028 626

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Grants of Options to Purchase Shares of Common Stock	The Company made the following grants of options to purchase shares of common stock during the years ended December 31, 2018 and 2017: 2018 2017 Options granted 27,000 340,387 Vesting period (years) 3-5 3-5 Expiration period (years) 10 10 Expected volatility 29.87 % 23.59% - 29.87% Expected life (years) 6.5 3.0 - 6.5 Expected dividend yield — — Risk free interest rate 2.68% - 2.77% 1.66% - 2.06% Option fair value $5.78 - $5.83 $2.71 - $5.05
Summary of Stock Options Grants	A summary of the status of the Company's stock option grants for the year ended December 31, 2018 is presented in the table below: Options Stock Option Grants Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value Balance at January 1, 2018 316,009 $ 14.66 9.78 $ 219,374 Granted 27,000 16.15 5.79 — Forfeited (30,304 ) 14.71 6.50 — Balance at December 31, 2018 312,705 $ 14.78 8.73 $ — Exercisable at December 31, 2018 59,936 $ 14.66 — $ — Unrecognized compensation cost (inclusive of directors' options) $ 1,075,000 Weighted average remaining recognition period (years) 3.62
Summary of Activity in Restricted Stock Awards Under Equity Plan	The following table presents the activity in restricted stock awards under the Equity Plan for the year ended December 31, 2018: Restricted Stock Awards Weighted Average Grant Price Restricted stock awards at January 1, 2018 176,239 $ 14.66 Granted — — Vested (33,835 ) 14.66 Forfeited (15,710 ) 14.66 Non-vested stock awards at December 31, 2018 126,694 $ 14.66 Unrecognized compensation cost $ 1,739,000 Weighted average remaining recognition period (years) 3.68

Earnings (Loss) Per Share (Tabl

Earnings (Loss) Per Share (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Schedule of Calculation of Average Number of Shares Outstanding Used to Calculate Basic and Diluted Earnings (Loss) Per Share	The following table sets forth the calculation of the average number of shares outstanding used to calculate the basic and diluted earnings (loss) per share for the periods indicated: 2018 2017 Average number of common shares outstanding 5,994,373 5,902,981 Less: Average unallocated ESOP shares (423,653 ) (434,467 ) 5,570,720 5,468,514

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rent Commitments	Pursuant to the terms of non-cancelable lease and sublease agreements in effect at December 31, 2018, future minimum rent commitments are as follows: Years Ending December 31, Leases Sub-lease Net (In thousands) 2019 $ 1,027 (87 ) $ 940 2020 919 (89 ) 830 2021 743 (91 ) 652 2022 545 (94 ) 451 2023 114 (16 ) 98 Thereafter — — — $ 3,348 $ (377 ) $ 2,971
Summary of Financial Instruments Outstanding Contract Amounts Represent Credit Risk	At December 31, 2018 and 2017, the following financial instruments were outstanding whose contract amounts represent credit risk: 2018 2017 (In thousands) Commitments to originate loans $ 38,404 $ 35,549 Unused lines and letters of credit 45,977 39,968 Unadvanced funds on construction loans 14,175 6,967 Overdraft lines of credit 8,475 8,996

Fair Value of Assets and Liab_2

Fair Value of Assets and Liabilities (Tables)	12 Months Ended
	Dec. 31, 2018
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. . Total Level 1 Level 2 Level 3 Fair December 31, 2018 (In thousands) Assets: Securities available for sale: Debt securities $ — $ 50,038 $ — $ 50,038 Mutual fund — 518 — 518 Portfolio loans (fair value option) 3,680 — 3,680 Loans held for sale (fair value option) — 38,474 — 38,474 Derivative loan commitments — 627 — 627 Forward loan sale commitments — 10 — 10 Liabilities: Forward loan sale commitments, including TBAs — 263 — 263 December 31, 2017 Assets: Securities available for sale: Debt securities $ — $ 61,043 $ — $ 61,043 Mutual fund — 533 — 533 Loans held for sale (fair value option) — 25,390 — 25,390 Derivative loan commitments — 363 — 363 Forward loan sale commitments — 4 — 4 Liabilities: Forward loan sale commitments — 19 — 19
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 and liabilities as of December 31, 2018 and 2017. The gains and losses represent the amounts recorded during 2018 and 2017 on the assets and liabilities held at year-end. There no liabilities recorded at fair value on a non-recurring basis as of December 31, 2018 and 2017. Year Ended December 31, 2018 December 31, 2018 Level 1 Level 2 Level 3 Total Assets: (In thousands) Collateral dependent impaired loans $ — $ — $ 1,352 $ — Mortgage servicing rights — 7,786 — 82 Assets held for sale — — — 2,476 Foreclosed real estate — — 65 (36 ) $ — $ 7,786 $ 1,417 $ 2,522 Year Ended December 31, 2017 December 31, 2017 Level 1 Level 2 Level 3 Total Gains (Losses) (In thousands) Collateral dependent impaired loans $ — $ — $ 1,630 $ — Mortgage servicing rights — 6,397 — 334 Assets held for sale — — 828 (225 ) Foreclosed real estate — — 193 — $ — $ 6,397 $ 2,651 $ 109
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 mortgagor’s escrow accounts and accrued interest payable. December 31, 2018 Carrying Fair Amount Value Level 1 Level 2 Level 3 (In thousands) Financial assets: Certificates of deposit $ 2,205 $ 2,196 $ — $ 2,196 $ — Securities available for sale 50,556 50,556 — 50,556 — Loans held for sale 38,474 38,474 — 38,474 — Loans, net 483,846 473,612 — — 473,612 Derivative assets 637 637 — 637 — Financial liabilities: Deposits $ 437,130 $ 435,964 $ — $ 435,964 $ — FHLBB advances 89,036 88,894 — 88,894 — Derivative liabilities 263 263 — 263 — December 31, 2017 Carrying Fair Amount Value Level 1 Level 2 Level 3 (In thousands) Financial assets: Certificates of deposit $ 3,675 $ 3,687 $ — $ 3,687 $ — Securities available for sale 68,637 68,637 — 68,637 — Loans held for sale 30,452 30,452 — 30,452 — Loans, net 332,991 331,132 — — 331,132 Derivative assets 682 682 — 682 — Financial liabilities: Deposits $ 351,179 $ 350,979 $ — $ 350,979 $ — FHLBB advances 38,667 38,531 — 38,531 — Derivative liabilities 47 47 — 47 —

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Summary of Segment Information	Segment information as of and for the year ended December 31, 2018, follows: For the Year Ended December 31, 2018 Envision Bank Envision Mortgage Consolidated Total (in thousands) Net interest income $ 15,664 $ 1,032 $ 16,696 Provision for loan losses 762 — 762 Net interest income after provision for loan losses 14,902 1,032 15,934 Non-interest income: Customer service fees 1,344 120 1,464 Gain on loan origination and sale activities, net (1) — 8,859 8,859 Mortgage servicing fees, net (310 ) 1,574 1,264 Gain on sales of buildings 2,476 — 2,476 Other 520 420 940 Total non-interest income 4,030 10,973 15,003 Non-interest expenses: Salaries and employee benefits 6,793 12,972 19,765 Occupancy and equipment 1,507 1,366 2,873 Restructuring charges — 968 968 Other non-interest expenses 4,476 3,590 8,066 Total non-interest expenses 12,776 18,896 31,672 Income (loss) before income taxes and elimination of inter-segment profit $ 6,156 $ (6,891 ) (735 ) Elimination of inter-segment profit (1,320 ) Loss before income taxes (2,055 ) Income tax expense 31 Net loss $ (2,086 ) Total assets, December 31, 2018 $ 526,871 $ 87,469 $ 614,340 (1) Before elimination of inter-segment profit Segment information as of and for the year ended December 31, 2017 follows: For the Year Ended December 31, 2017 Envision Bank Envision Mortgage Consolidated Total (in thousands) Net interest income $ 13,827 $ 1,003 $ 14,830 Provision for loan losses 540 — 540 Net interest income after provision for loan losses 13,287 1,003 14,290 Non-interest income: Customer service fees 1,355 100 1,455 Gain on loan origination and sale activities, net (1) — 10,047 10,047 Mortgage servicing fees, net (258 ) 1,731 1,473 Other 408 476 884 Total non-interest income 1,505 12,354 13,859 Non-interest expenses: Salaries and employee benefits 6,243 12,488 18,731 Occupancy and equipment 1,392 1,263 2,655 Restructuring charges — 594 594 Merger and integration costs 19 512 531 Other non-interest expenses 3,955 3,356 7,311 Total non-interest expenses 11,609 18,213 29,822 Income (loss) before income taxes and elimination of inter-segment profit $ 3,183 $ (4,856 ) (1,673 ) Elimination of inter-segment profit (896 ) Loss before income taxes (2,569 ) Income tax benefit (443 ) Net loss $ (2,126 ) Total assets, December 31, 2017 $ 468,515 $ 63,377 $ 531,892 (1) Before elimination of inter-segment profit

Other Non-Interest Expenses (Ta

Other Non-Interest Expenses (Tables)	12 Months Ended
	Dec. 31, 2018
Other Income And Expenses [Abstract]
Schedule of Company's Total Interest and Non-Interest Income Included in Other Non-Interest Expenses	Included in other non-interest expenses in 2018 and 2017 are certain items exceeding 1% of the Company’s total interest and non-interest income as follows: 2018 2017 (In thousands) Software amortization and maintenance $ 754 $ 789 Card related expenses 470 359 Data communication and telephone 495 463 Directors fees, including stock-based compensation 613 407

Parent Company Condensed Fina_2

Parent Company Condensed Financial Statements (Tables)	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Balance Sheets	Financial information as of December 31, 2018 and 2017 and for the years then ended pertaining to Randolph Bancorp, Inc. is as follows: BALANCE SHEETS December 31, December 31, 2018 2017 Assets Cash and due from bank $ 6,850 $ 8,187 Due from Envision Bank — 141 Investment in Envision Bank 66,971 68,777 ESOP loan 4,266 4,378 Total assets $ 78,087 $ 81,483 Liabilities Accounts payable $ 70 $ — Due to Envision Bank 56 — 126 — Total liabilities Stockholders' Equity Common stock 60 61 Additional paid-in capital 55,608 56,493 Retained earnings 28,329 30,415 ESOP-Unearned compensation (4,132 ) (4,319 ) Accumulated other comprehensive loss, net of tax (1,904 ) (1,167 ) Total stockholders' equity 77,961 81,483 Total liabilities and stockholders' equity $ 78,087 $ 81,483
Statements of Operations	Financial information as of December 31, 2018 and 2017 and for the years then ended pertaining to Randolph Bancorp, Inc. is as follows: STATEMENTS OF OPERATIONS Years Ended December 31, 2018 2017 Interest income $ 197 $ 169 Operating expenses 197 308 Loss before incomes taxes and equity in undistributed net loss of Envision Bank — (139 ) Applicable income taxes — — Loss before equity in undistributed net loss of Envision Bank — (139 ) Equity in undistributed net loss of Envision Bank (2,086 ) (1,987 ) Net loss $ (2,086 ) $ (2,126 )
Statements of Cash Flows	Financial information as of December 31, 2018 and 2017 and for the years then ended pertaining to Randolph Bancorp, Inc. is as follows: STATEMENTS OF CASH FLOWS Years Ended December 31, 2018 2017 Cash flows from operating activities: Net loss $ (2,086 ) $ (2,126 ) Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Equity in undistributed net loss of Envision Bank 2,086 1,987 Change in intercompany receivable/payable 197 (139 ) Net cash provided by (used in) operating activities 197 (278 ) Cash flows from investing activities: Payments received on ESOP loan 112 129 Net cash provided by investing activities 112 129 Cash flows from financing activities: Stock repurchases (1,716 ) (160 ) Stock repurchase payable 70 — Net cash used in financing activities (1,646 ) (160 ) Net change in cash and cash equivalents (1,337 ) (309 ) Cash and cash equivalents at the beginning of year 8,187 8,496 Cash and cash equivalents at end of year $ 6,850 $ 8,187

Selected Quarterly Financial _2

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Summary of Selected Quarterly Financial Data	First Quarter Second Quarter Third Quarter Fourth Quarter 2018 2017 2018 2017 2018 2017 2018 2017 (Dollars in thousands, except per share data) Interest and dividend income $ 4,727 $ 3,884 $ 5,039 $ 4,175 $ 5,468 $ 4,389 $ 6,050 $ 4,492 Interest expense 745 400 1,006 485 1,208 573 1,630 652 Net interest and dividend income 3,982 3,484 4,033 3,690 4,260 3,816 4,420 3,840 Provision (credit) for loan losses 95 235 (90 ) 100 178 — 579 205 Gain on loan origination and sales activities, net 1,547 2,038 1,854 2,520 1,956 2,705 2,183 1,888 Other non-interest income 861 1,372 929 914 1,252 866 3,102 660 Total non-interest income 2,408 3,410 2,783 3,434 3,208 3,571 5,285 2,548 Merger and integration costs — 167 — 357 — 7 — — Other non-interest expense 6,998 6,962 7,912 7,071 7,427 7,202 9,337 8,056 Total non-interest expense 6,998 7,129 7,912 7,428 7,427 7,209 9,337 8,056 Provision (benefit) for income taxes 4 (23 ) 4 (254 ) 5 129 17 (295 ) Net income (loss) $ (707 ) $ (447 ) $ (1,010 ) $ (150 ) $ (142 ) $ 49 $ (228 ) $ (1,578 ) Basic and diluted earnings (loss) per share $ (0.13 ) $ (0.08 ) $ (0.18 ) $ (0.03 ) $ (0.03 ) $ 0.01 $ (0.04 ) $ (0.28 ) Weighted average common shares (basic and diluted) 5,603,886 5,420,356 5,580,683 5,425,033 5,567,596 5,429,564 5,526,416 5,597,762

Basis of Presentation and Sum_4

Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018USD ($)Segmentshares	Dec. 31, 2017USD ($)shares
Summary Of Significant Accounting Policies [Line Items]
Entity information date of corporate name change form Randolph Savings Bank to Envision Bank	Mar. 12, 2018
Cash equivalents maturity period	90 days
Time period to capture relevant loan loss data	48 months
Obligation to repurchase mortgage loans prescribed time period	4 months
Description of tax benefit	A tax position is recognized as a benefit if it is “more likely than not” that the tax position would be sustained in a tax examination, with a tax examination being presumed to occur. The amount recognized is the largest amount of tax benefit greater than 50% likely of being realized on examination. For tax positions not meeting the “more likely than not” test, no tax benefit is recorded.
Uncertain tax positions	$ 0	$ 0
Interest or penalties	$ 0	$ 0
Number of operating segment | Segment	1
Number of business segments | Segment	2
Anti-dilutive securities excluded from computation of earnings (loss) per share | shares	0	0
Supplemental Retirement Plan [Member]
Summary Of Significant Accounting Policies [Line Items]
Prior service credits	$ 89,000
Net actuarial losses	$ 41,000
Consumer Loans or Second Mortgages and HELOCs [Member]
Summary Of Significant Accounting Policies [Line Items]
Impairment disclosure requirement	Unless such loans are 90 days past due or are classified as a troubled debt restructuring.
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
FDIC insurance coverage limit	$ 250,000
Certificates of deposit maturity period	5 years
Maximum [Member] | Residential One-to-Four Family Real Estate Portfolio Segment [Member]
Summary Of Significant Accounting Policies [Line Items]
Loan-to-value ratio	80.00%
Maximum [Member] | Second Mortgages and Home Equity Lines of Credit Property Segment [Member]
Summary Of Significant Accounting Policies [Line Items]
Loan-to-value ratio	80.00%
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Certificates of deposit maturity period	1 year
Percentage of tax benefit that likely of being realized on examination with taxing authority	50.00%

Basis of Presentation and Sum_5

Basis of Presentation and Summary of Significant Accounting Policies - Components of Accumulated Other Comprehensive Loss (AOCI) and Related Tax Effects (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income Loss [Line Items]
Total other comprehensive loss	$ (737)	$ (3)
Accumulated other comprehensive loss	(1,904)	(1,167)
Accumulated Net Investment Gain (Loss) Attributable to Parent
Accumulated Other Comprehensive Income Loss [Line Items]
Net unrealized loss	(1,334)	(624)
Other comprehensive Loss, Tax effect	(313)	(313)
Total other comprehensive loss	(1,647)	(937)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Net unrealized loss	(605)	(667)
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Net unrealized loss	395	484
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Net unrealized loss	(210)	(183)
Other comprehensive Loss, Tax effect	(47)	(47)
Total other comprehensive loss	$ (257)	$ (230)

Securities Available for Sale -

Securities Available for Sale - Schedule of Amortized Cost and Fair Value of Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 51,890	$ 62,199
Gross Unrealized Gains	110	403
Gross Unrealized Losses	(1,444)	(1,026)
Fair Value	50,556	61,576
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	51,372	61,654
Gross Unrealized Gains	110	403
Gross Unrealized Losses	(1,444)	(1,014)
Fair Value	50,038	61,043
Debt Securities [Member] | US Government-sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,999	3,999
Gross Unrealized Gains	13	50
Gross Unrealized Losses	(31)	(24)
Fair Value	3,981	4,025
Debt Securities [Member] | Corporate [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,524	2,005
Gross Unrealized Gains	6	27
Gross Unrealized Losses	(18)	(8)
Fair Value	1,512	2,024
Debt Securities [Member] | Municipal [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,489	12,707
Gross Unrealized Gains	18	179
Gross Unrealized Losses		(18)
Fair Value	1,507	12,868
Debt Securities [Member] | Residential Mortgage-backed Securities, US Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	26,989	18,729
Gross Unrealized Gains	71	118
Gross Unrealized Losses	(754)	(450)
Fair Value	26,306	18,397
Debt Securities [Member] | Commercial Mortgage-backed Securities, US Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	9,094	14,451
Gross Unrealized Gains		13
Gross Unrealized Losses	(487)	(403)
Fair Value	8,607	14,061
Debt Securities [Member] | Commercial Mortgage Backed Securities, U.S. Government-guaranteed [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,796	2,132
Gross Unrealized Losses	(33)	(6)
Fair Value	1,763	2,126
Debt Securities [Member] | Collateralized Mortgage Obligations, US Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,642	1,871
Gross Unrealized Gains		12
Gross Unrealized Losses	(17)	(5)
Fair Value	1,625	1,878
Debt Securities [Member] | Collateralized Mortgage Obligations, US Government Guaranteed [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,839	5,760
Gross Unrealized Gains	2	4
Gross Unrealized Losses	(104)	(100)
Fair Value	4,737	5,664
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	518	545
Gross Unrealized Losses		(12)
Fair Value	$ 518	$ 533

Securities Available for Sale_2

Securities Available for Sale - Investments Classified by Contractual Maturity Date (Detail) $ in Thousands	Dec. 31, 2018USD ($)
Available-for-sale Securities, Debt Maturities, Amortized Cost
After 1 year through 5 years	$ 6,173
After 5 years through 10 years	839
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis, Total	7,012
Mortgage-backed securities and collaterlized mortgage obligations	44,360
Available-for-sale Debt Securities, Amortized Cost Basis, Total	51,372
Available-for-sale Securities, Debt Maturities, Fair Value
After 1 year through 5 years	6,149
After 5 years through 10 years	851
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Fair Value Total	7,000
Mortgage-backed securities and collaterlized mortgage obligations	43,038
Available-for-sale Securities, Debt Securities, Fair Value Total	$ 50,038

Securities Available for Sale_3

Securities Available for Sale - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018USD ($)Debt_Security	Dec. 31, 2017USD ($)
Schedule of Available-for-sale Securities [Line Items]
Fair value of investment securities pledged as collateral	$ 2,010,000	$ 2,004,000
Number of debt securities with unrealized losses | Debt_Security	35
Unrealized losses debt securities aggregate depreciation percentage	3.58%
Proceeds from the sale of securities	$ 8,958,000
Available-for-sale securities, gross realized gains	49,000
Prepayment of Commercial Mortgage-backed Security [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, gross realized losses	33,000
OTTI Write-down of Mutual Fund [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, gross realized losses	27,000
Minimum [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment securities on equity	$ 0	$ 0

Securities Available for Sale_4

Securities Available for Sale - Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Less Than Twelve Months, Gross Unrealized Losses		$ (24)
Less Than Twelve Months, Fair Value		6,641
Over Twelve Months, Gross Unrealized Losses		(1,002)
Over Twelve Months, Fair Value		47,400
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than Twelve Months, Gross Unrealized Losses	$ (11)	(24)
Less Than Twelve Months, Fair Value	7,535	6,641
Over Twelve Months, Gross Unrealized Losses	(1,433)	(990)
Over Twelve Months, Fair Value	31,330	46,867
Debt Securities [Member] | US Government-sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Over Twelve Months, Gross Unrealized Losses	(31)	(24)
Over Twelve Months, Fair Value	1,969	19,676
Debt Securities [Member] | Corporate [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than Twelve Months, Gross Unrealized Losses	(5)
Less Than Twelve Months, Fair Value	497
Over Twelve Months, Gross Unrealized Losses	(13)	(8)
Over Twelve Months, Fair Value	506	988
Debt Securities [Member] | Municipal [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than Twelve Months, Gross Unrealized Losses		(11)
Less Than Twelve Months, Fair Value		1,919
Over Twelve Months, Gross Unrealized Losses		(7)
Over Twelve Months, Fair Value		479
Debt Securities [Member] | Residential Mortgage-backed Securities, US Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than Twelve Months, Gross Unrealized Losses	(6)	(1)
Less Than Twelve Months, Fair Value	7,038	1,623
Over Twelve Months, Gross Unrealized Losses	(748)	(449)
Over Twelve Months, Fair Value	12,981	13,163
Debt Securities [Member] | Commercial Mortgage-backed Securities, US Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Over Twelve Months, Gross Unrealized Losses	(487)	(403)
Over Twelve Months, Fair Value	8,607	8,805
Debt Securities [Member] | Commercial Mortgage Backed Securities, U.S. Government-guaranteed [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than Twelve Months, Gross Unrealized Losses		(6)
Less Than Twelve Months, Fair Value		2,126
Over Twelve Months, Gross Unrealized Losses	(33)
Over Twelve Months, Fair Value	1,763
Debt Securities [Member] | Collateralized Mortgage Obligations, 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		678
Over Twelve Months, Gross Unrealized Losses	(17)
Over Twelve Months, Fair Value	1,625
Debt Securities [Member] | Collateralized Mortgage Obligations, US Government Guaranteed [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than Twelve Months, Gross Unrealized Losses		(1)
Less Than Twelve Months, Fair Value		295
Over Twelve Months, Gross Unrealized Losses	(104)	(99)
Over Twelve Months, Fair Value	$ 3,879	3,756
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Over Twelve Months, Gross Unrealized Losses		(12)
Over Twelve Months, Fair Value		$ 533

Loans - Summary of Loan Portfol

Loans - Summary of Loan Portfolio (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 486,774	$ 402,658
Allowance for loan losses	(4,437)	(3,737)
Net deferred loan costs and fees, and purchase premiums	1,509	1,452
Net loans	483,846	400,373
Real Estate Sector [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	446,082	361,555
Commercial Real Estate Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	113,642	98,755
Commercial Real Estate Loans [Member] | Real Estate Sector [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	113,642	98,755
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	21,285	24,766
Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	19,407	16,337
One-to-Four Family [Member] | Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	246,756	198,475
One-to-Four Family [Member] | Residential Real Estate [Member] | Real Estate Sector [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	246,756	198,475
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	43,545	38,968
Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	42,139	25,357
Construction [Member] | Real Estate Sector [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 42,139	$ 25,357

Loans - Additional Information

Loans - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018USD ($)TDR	Dec. 31, 2017USD ($)TDR
Accounts, Notes, Loans and Financing Receivable [Line Items]
Servicing loans for participants	$ 5,596,000	$ 5,902,000
Impaired loans, additional funds committed	$ 0
Loans subject to troubled debt restructurings | TDR	1
Troubled debt restructuring amount		0
Allowances related to troubled debt restructurings	$ 282,000	162,000
Minimum past due days for loan rating	90 days
Total loans	$ 486,774,000	402,658,000
Consumer Loans [Member] | Doubtful [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	149,000,000
Consumer Loans [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	50,000,000
Residential Mortgage [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	2,469,000	712,000
Residential Mortgage [Member] | Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	936,000	2,512,000
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
Modified Loan Agreements [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructuring amount	3,341,000	4,315,000
Non Accrual Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructuring amount	366,000	1,085,000
Home Equity Loans and Lines of Credit [Member] | Special Mention [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	$ 407,000	$ 247,000
Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans subject to troubled debt restructurings | TDR	17	19
Loans subject to troubled debt restructurings, amount	$ 3,341,000	$ 4,315,000
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	1	2
Loans subject to troubled debt restructurings, amount	$ 52,000	$ 153,000
Total loans	$ 113,642,000	98,755,000
Commercial Real Estate Loans [Member] | Substandard [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		$ 199,000
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 - Summary of Activity in

Loans - Summary of Activity in the Allowance for Loan Losses by Loan Category (Detail) - USD ($) $ in Thousands	3 Months Ended							12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				$ 3,737			$ 3,271	$ 3,737	$ 3,271
Provision (credit) for loan losses	$ 579	$ 178	$ (90)	95	$ 205	$ 100	235	762	540
Loans charged-off								(121)	(153)
Recoveries								59	79
Ending balance	4,437				3,737			4,437	3,737
Commercial Real Estate Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				1,620			1,410	1,620	1,410
Provision (credit) for loan losses								30	210
Loans charged-off								(2)
Ending balance	1,648				1,620			1,648	1,620
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				335			37	335	37
Provision (credit) for loan losses								(70)	263
Recoveries									35
Ending balance	265				335			265	335
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				218			145	218	145
Provision (credit) for loan losses								258	205
Loans charged-off								(119)	(153)
Recoveries								18	21
Ending balance	375				218			375	218
One-to-Four Family [Member] | Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				854			1,018	854	1,018
Provision (credit) for loan losses								197	(187)
Recoveries								41	23
Ending balance	1,092				854			1,092	854
Second Mortgages and HELOC [Member] | Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				359			436	359	436
Provision (credit) for loan losses								(67)	(77)
Ending balance	292				359			292	359
Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				$ 351			$ 225	351	225
Provision (credit) for loan losses								414	126
Ending balance	$ 765				$ 351			$ 765	$ 351

Loans - Summary of Additional I

Loans - Summary of Additional Information Pertaining to the Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for impaired loans	$ 282	$ 162
Allowance for non-impaired loans	4,155	3,575
Total allowance for loan losses	4,437	3,737	$ 3,271
Impaired loans	6,950	5,833
Non-impaired loans	479,824	396,825
Total loans	486,774	402,658
Commercial Real Estate Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for impaired loans		1
Allowance for non-impaired loans	1,648	1,619
Total allowance for loan losses	1,648	1,620	1,410
Impaired loans	52	352
Non-impaired loans	113,590	98,403
Total loans	113,642	98,755
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for non-impaired loans	265	335
Total allowance for loan losses	265	335	37
Non-impaired loans	21,285	24,766
Total loans	21,285	24,766
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for impaired loans	174
Allowance for non-impaired loans	201	218
Total allowance for loan losses	375	218	145
Impaired loans	199
Non-impaired loans	19,208	16,337
Total loans	19,407	16,337
One-to-Four Family [Member] | Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for impaired loans	108	160
Allowance for non-impaired loans	984	694
Total allowance for loan losses	1,092	854	1,018
Impaired loans	6,291	5,205
Non-impaired loans	240,465	193,270
Total loans	246,756	198,475
Second Mortgages and HELOC [Member] | Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for impaired loans		1
Allowance for non-impaired loans	292	358
Total allowance for loan losses	292	359	436
Impaired loans	408	276
Non-impaired loans	43,137	38,692
Total loans	43,545	38,968
Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for non-impaired loans	765	351
Total allowance for loan losses	765	351	$ 225
Non-impaired loans	42,139	25,357
Total loans	$ 42,139	$ 25,357

Loans - Schedule of Past Due an

Loans - Schedule of Past Due and Non-Accrual Loans by Loan Category (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 2,046	$ 833
Non-accrual Loans	3,030	2,251
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	29
Non-accrual Loans	149
30 - 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,200	833
30 - 59 Days Past Due [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	25
60 - 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	211
60 - 89 Days Past Due [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4
90 Days or More Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	635
One-to-Four Family [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,497	737
Non-accrual Loans	2,474	1,975
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	655	737
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	207
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	635
Home Equity Loans and Lines of Credit [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	520	96
Non-accrual Loans	407	276
Home Equity Loans and Lines of Credit [Member] | 30 - 59 Days Past Due [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 520	$ 96

Loans - Summary of Impaired Loa

Loans - Summary of Impaired Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Recorded Investment without a valuation allowance	$ 4,740	$ 3,145
Unpaid Principal Balance without a valuation allowance	4,740	3,145
Recorded Investment with a valuation allowance	2,210	2,688
Unpaid Principal Balance with a valuation allowance	2,210	2,688
Related Allowance, Total impaired loans	282	162
Recorded Investment, Total impaired loans	6,950	5,833
Unpaid Principal Balance, Total impaired loans	6,950	5,833
Commercial Real Estate Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment without a valuation allowance	52	257
Unpaid Principal Balance without a valuation allowance	52	257
Recorded Investment with a valuation allowance		95
Unpaid Principal Balance with a valuation allowance		95
Related Allowance, Total impaired loans		1
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment with a valuation allowance	199
Unpaid Principal Balance with a valuation allowance	199
Related Allowance, Total impaired loans	174
One-to-Four Family [Member] | Residential Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment without a valuation allowance	4,280	2,641
Unpaid Principal Balance without a valuation allowance	4,280	2,641
Recorded Investment with a valuation allowance	2,011	2,564
Unpaid Principal Balance with a valuation allowance	2,011	2,564
Related Allowance, Total impaired loans	108	160
Home Equity Loans and Lines of Credit [Member] | Residential Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment without a valuation allowance	408	247
Unpaid Principal Balance without a valuation allowance	$ 408	247
Recorded Investment with a valuation allowance		29
Unpaid Principal Balance with a valuation allowance		29
Related Allowance, Total impaired loans		$ 1

Loans - Summary of Information

Loans - Summary of Information Related to Average Balances of Impaired Loans and Interest Income Recognized (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	$ 7,495	$ 5,887
Interest Income Recognized	263	232
Cash Basis Interest Recognized	120	83
Residential Real Estate [Member] | One-to-Four Family [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	6,781	4,956
Interest Income Recognized	210	195
Cash Basis Interest Recognized	84	82
Residential Real Estate [Member] | Home Equity Loans and Lines of Credit [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	420	276
Interest Income Recognized	36	1
Cash Basis Interest Recognized	36	1
Commercial Real Estate Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	244	655
Interest Income Recognized	15	$ 36
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	50
Interest Income Recognized	$ 2

Loans - Summary of Company's Lo

Loans - Summary of Company's Loans by Risk Rating (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$ 486,774	$ 402,658
Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	42,139	25,357
Commercial Real Estate Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	113,642	98,755
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	21,285	24,766
Pass [Member] | Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	42,139	25,357
Pass [Member] | Commercial Real Estate Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	113,642	98,556
Pass [Member] | Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$ 21,285	24,766
Substandard [Member] | Commercial Real Estate Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans		$ 199

Loan Servicing - Additional Inf

Loan Servicing - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016
Servicing Assets At Amortized Value [Line Items]
Unpaid principal balances of residential mortgage loans serviced for others	$ 929,289,000	$ 771,407,000
Contractually specified servicing fees, net	$ 2,165,000	$ 2,434,000
Measurement Input, Discount Rate [Member]
Servicing Assets At Amortized Value [Line Items]
Discount rate	0.12	0.13	0.14
Measurement Input, Constant Prepayment Rate [Member] | Minimum [Member]
Servicing Assets At Amortized Value [Line Items]
Discount rate	0.07	0.06
Measurement Input, Constant Prepayment Rate [Member] | Maximum [Member]
Servicing Assets At Amortized Value [Line Items]
Discount rate	0.35	0.24

Loan Servicing - Summary of Act

Loan Servicing - Summary of Activity In Company's Mortgage Servicing Rights (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Mortgage servicing rights:
Balance at beginning of year	$ 6,397	$ 8,486
Additions through originations	2,380	2,310
Amortization	(983)	(1,071)
Sales		(3,238)
Balance at end of year	7,794	6,487
Valuation allowance:
Balance at beginning of year	90	424
Provision (credit)	(82)	(334)
Balance at end of year	8	90
Mortgage servicing rights, amortized cost	7,786	6,397
Mortgage servicing rights, fair value	$ 8,554	$ 6,485

Premises and Equipment - Summar

Premises and Equipment - Summary of Cost and Accumulated Depreciation and Amortization of Premises and Equipment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property Plant And Equipment [Line Items]
Land and improvements	$ 1,025	$ 2,525
Buildings and improvements	3,280	4,457
Leasehold improvements	2,136	1,503
Furniture and equipment	5,032	4,765
Construction-in-progress	84	101
Property plant and equipment, gross	11,557	13,351
Less accumulated depreciation and amortization	(5,189)	(4,681)
Property plant and equipment, net	$ 6,368	$ 8,670
Buildings and Improvements [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Estimated Useful Life	5 years
Buildings and Improvements [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Estimated Useful Life	50 years
Leasehold Improvements [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Estimated Useful Life	3 years
Leasehold Improvements [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Estimated Useful Life	10 years
Furniture and Equipment [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Estimated Useful Life	3 years
Furniture and Equipment [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Estimated Useful Life	10 years

Premises and Equipment - Additi

Premises and Equipment - Additional Information (Detail)	Jul. 31, 2018	Oct. 31, 2018ft²	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2018USD ($)Office	Dec. 31, 2017USD ($)
Property Plant And Equipment [Line Items]
Depreciation and amortization expense					$ 835,000	$ 605,000
Leasehold improvements funded by landlord						$ 646,000
Leasehold improvements allowance amortized period						5 years
Tenant improvement allowance amortized period						5 years
Percentage of land occupied under sublease agreement	27.00%
Termination of lease	2023
Impairment write-down of assets held for sale				$ 225,000	$ 166,000	$ 225,000
Number of branches sold | Office					3
Number of branch office replaced | Office					2
Gain (loss) on sale of building					$ 2,476,000
Branch Office [Member]
Property Plant And Equipment [Line Items]
Impairment write-down of assets held for sale						225,000
Assets held for sale				$ 828,000		$ 828,000
Gain (loss) on sale of building					2,476,000
Branch Office, Two [Member]
Property Plant And Equipment [Line Items]
Gain (loss) on sale of building					(15,000)
Branch Office, Other [Member]
Property Plant And Equipment [Line Items]
Gain (loss) on sale of building					230,000
Boston [Member] | Branch Office [Member]
Property Plant And Equipment [Line Items]
Gain (loss) on sale of building					2,261,000
Consideration received			$ 5,000,000		5,000,000
Boston [Member] | Branch Office [Member] | Insurance Recovery [Member]
Property Plant And Equipment [Line Items]
Insurance recovery for personal property					90,000
Consolidation of Mortgage Banking Operations [Member]
Property Plant And Equipment [Line Items]
Impairment write-down of assets held for sale			168,000
Consolidation of Mortgage Banking Operations [Member] | Restructuring Charges [Member] | Furniture and Equipment [Member]
Property Plant And Equipment [Line Items]
Impairment write-down of assets held for sale			168,000
Consolidation of Mortgage Banking Operations [Member] | Andover [Member]
Property Plant And Equipment [Line Items]
Remaining space available to sublease | ft²		8,600
Fair value, Cease use liability			$ 565,000		$ 565,000

Deposits - Summary of Deposit B

Deposits - Summary of Deposit Balances by Type (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deposits [Abstract]
Demand deposits	$ 64,229	$ 62,130
NOW accounts	42,802	44,988
Money market deposits	60,843	56,668
Regular and other savings	101,137	102,528
Brokered deposits	10,088	7,106
Total non-certificate accounts	279,099	273,420
Term certificates less than $250,000	99,491	80,538
Term certificates of $250,000 or more	8,048	12,878
Term certificates - brokered	50,492
Total certificate accounts	158,031	93,416
Total deposits	$ 437,130	$ 366,836

Deposits - Summary of Term Cert

Deposits - Summary of Term Certificates, Including Brokered Deposits, by Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Amount
2018		$ 49,550
2019	$ 89,167	22,470
2020	40,847	8,754
2021	12,785	4,873
2022	14,101	7,769
2023	1,131
Total certificate accounts	$ 158,031	$ 93,416
Weighted Average Rate
2018		0.84%
2019	1.68%	1.20%
2020	2.16%	1.44%
2021	2.16%	1.57%
2022	1.98%	1.65%
2023	1.38%
Total	1.87%	1.09%

Borrowings - Summary of Borrowi

Borrowings - Summary of Borrowings from FHLBB (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fixed-rate advances maturing:
2018		$ 69,337
2019	$ 84,184	1,500
2020	2,894	3,129
2021	1,958	1,988
Advances from FHLBB, Amount	$ 89,036	$ 75,954
Weighted Average Rate
2018		1.55%
2019	2.57%	1.00%
2020	1.49%	1.52%
2021	1.33%	1.34%
Advances from FHLBB, Weighted Average Rate	2.50%	1.54%

Borrowings - Additional Informa

Borrowings - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Overnight advances of FHLBB borrowings	$ 82,700,000	$ 64,700,000
Federal Home Loan Bank advances	89,036,000	75,954,000
Correspondent Bank [Member]
Debt Instrument [Line Items]
Available borrowing capacity	7,500,000
Federal Home Loan Bank advances	$ 0	0
FHLBB [Member]
Debt Instrument [Line Items]
Percentage on carrying value of first mortgage loans pledged as collateral	75.00%
Available borrowing capacity	$ 90,346,000
FHLBB [Member] | Commercial Real Estate Loans [Member]
Debt Instrument [Line Items]
Percentage on carrying value of first mortgage loans pledged as collateral	65.00%
FHLBB With Interest Rate Adjusts Daily [Member]
Debt Instrument [Line Items]
Available borrowing capacity	$ 4,195,000
Federal Home Loan Bank advances	$ 0	0
FHLBB With Interest Rate Adjusts Daily [Member] | Maximum [Member]
Debt Instrument [Line Items]
Percentage on total assets for borrowings under line of credit	2.00%
Federal Reserve Bank of Boston [Member]
Debt Instrument [Line Items]
Available borrowing capacity	$ 10,000,000
Federal Home Loan Bank advances	$ 0	$ 0

Borrowings - Summary of Outstan

Borrowings - Summary of Outstanding Balances of Short Term Borrowings from FHLBB (Detail) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Federal Home Loan Bank Advances Activity For Year [Abstract]
Average daily balance	$ 63,552,000	$ 34,656,000
Maximum outstanding at any month end	$ 108,819,000	$ 64,739,000

Income Taxes - Allocation of Fe

Income Taxes - Allocation of Federal and State Income Taxes Between Current and Deferred Portions (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Current tax expense (benefit):
Federal										$ (462)
State									$ 31	19
Total current tax expense (benefit)									31	(443)
Deferred tax expense (benefit):
Federal									(541)	(518)
Effect of change in federal tax rate										1,627
State									73	(23)
Total deferred federal and state tax expense (benefit)									(468)	1,086
Change in valuation allowance									468	541
Effect of change in federal tax rate - valuation allowance										(1,627)
Total tax expense (benefit)	$ 17	$ 5	$ 4	$ 4	$ (295)	$ 129	$ (254)	$ (23)	$ 31	$ (443)

Income Taxes - Summary of Diffe

Income Taxes - Summary of Differences Between Statutory Federal Income Tax Expense (Benefit) and Actual Tax Expense (Benefit) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Income Tax Expense Benefit Continuing Operations Income Tax Reconciliation [Abstract]
Statutory federal tax (21% in 2018 and 34% in 2017)									$ (432)	$ (874)
Increase (decrease) resulting from:
State taxes, net of federal tax effect									83	(3)
Bank-owned life insurance									(46)	(52)
Tax exempt income									(25)	(118)
Dividends received deduction										(5)
Change in valuation allowance									468	541
Change in AOCI deferred effect										(36)
Effect of change in federal tax rate										1,627
Effect of change in federal tax rate-valuation allowance										(1,627)
Other, net									(17)	104
Total tax expense (benefit)	$ 17	$ 5	$ 4	$ 4	$ (295)	$ 129	$ (254)	$ (23)	$ 31	$ (443)

Income Taxes - Summary of Dif_2

Income Taxes - Summary of Differences Between Statutory Federal Income Tax Expense (Benefit) and Actual Tax Expense (Benefit) (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Statutory federal tax rate	21.00%	34.00%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax [Line Items]
Alternative minimum tax refundable period	4 years
Corporate income tax rate	21.00%	34.00%
Change in valuation allowance		$ 1,627,000
Charitable contribution carryforward	$ 2,481,000
Federal income tax reserve for loan losses	$ 2,033,000
Percentage of tax reserve for loan losses used for purpose other than to absorb losses subject to taxation	150.00%
Deferred income tax liability not been provided	$ 571,000
Federal [Member]
Income Tax [Line Items]
Net operating loss carryforward	13,638,000
Operating Loss Carryforwards Expires on December 31, 2033 [Member] | Federal [Member]
Income Tax [Line Items]
Net operating loss carryforward	$ 4,745,000
Operating loss carryforward expiration date	Dec. 31, 2033
Operating Loss Carryforwards Expires on December 31, 2034 [Member] | Federal [Member]
Income Tax [Line Items]
Net operating loss carryforward	$ 406,000
Operating loss carryforward expiration date	Dec. 31, 2034
Operating Loss Carryforward Expires on December 31, 2035 [Member] | Federal [Member]
Income Tax [Line Items]
Net operating loss carryforward	$ 1,542,000
Operating loss carryforward expiration date	Dec. 31, 2035
Operating Loss Carryforward Expires on December 31, 2036 [Member] | Federal [Member]
Income Tax [Line Items]
Net operating loss carryforward	$ 501,000
Operating loss carryforward expiration date	Dec. 31, 2036
Operating Loss Carryforward Expires on December 31, 2037 [Member] | Federal [Member]
Income Tax [Line Items]
Net operating loss carryforward	$ 2,871,000
Operating loss carryforward expiration date	Dec. 31, 2037
Operating Loss Carryforward No Expiration [Member] | Federal [Member]
Income Tax [Line Items]
Net operating loss carryforward	$ 3,573,000
Deferred Tax Assets Charitable Contribution Carryforward Expires on December 31, 2021 [Member]
Income Tax [Line Items]
Charitable contribution carryforward	$ 174,000
Charitable contributions carryforward expiration years	Dec. 31, 2021
Maximum [Member]
Income Tax [Line Items]
Corporate income tax rate		35.00%

Income Taxes - Summary of Compo

Income Taxes - Summary of Components of Net Deferred Tax Asset (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Deferred tax assets, gross	$ 6,268	$ 5,255
Valuation allowance	(3,246)	(2,778)
Deferred tax assets, net	3,022	2,477
Deferred tax liabilities:
Deferred tax liabilities, gross	(3,022)	(2,477)
Federal [Member]
Deferred tax assets:
Deferred tax assets, gross	5,134	4,247
Deferred tax liabilities:
Deferred tax liabilities, gross	(2,189)	(1,806)
State [Member]
Deferred tax assets:
Deferred tax assets, gross	1,134	1,008
Deferred tax liabilities:
Deferred tax liabilities, gross	$ (833)	$ (671)

Income Taxes - Summary of Defer

Income Taxes - Summary of Deferred Tax Asset (Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Employee benefit plans	$ 825	$ 951
Allowance for loan losses	1,247	1,050
Funded status of post-retirement benefits	(47)	(47)
Securities available for sale	(313)	(313)
Depreciation and amortization	249	193
Net deferred loan origination costs	(357)	(321)
Mortgage servicing rights	(2,082)	(1,624)
Net operating loss carryforward	2,864	2,171
Charitable contribution carryforward	700	702
Derivatives	(105)	(98)
Stock-based compensation	121	48
Other, net	144	66
Deferred tax assets (liabilities) before valuation allowances	3,246	2,778
Valuation allowance on deferred tax assets	$ (3,246)	$ (2,778)

On-Balance Sheet Derivative I_2

On-Balance Sheet Derivative Instruments and Hedging Activities - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Derivative Loan Commitments [Member]
Derivative [Line Items]
Derivative, Notional amount	$ 36,852,000	$ 24,222,000
Derivative Loan Commitments [Member] | Net Gain on Sales of Mortgage Loans [Member]
Derivative [Line Items]
Increase (reductions) in aggregate fair value on derivatives, interest rate lock commitments	264,000	(254,000)
Undesignated Forward Loan Sale Commitments [Member]
Derivative [Line Items]
Derivative, Notional amount	42,021,000	29,613,000
Undesignated Forward Loan Sale Commitments [Member] | Net Gain on Sales of Mortgage Loans [Member]
Derivative [Line Items]
Increase (reductions) in aggregate fair value on derivatives, interest rate lock commitments	238,000	66,000
Other Assets [Member] | Derivative Loan Commitments [Member]
Derivative [Line Items]
Derivative fair value, Asset	627,000	363,000
Other Assets [Member] | Undesignated Forward Loan Sale Commitments [Member]
Derivative [Line Items]
Derivative fair value, Asset	10,000	4,000
Other Liabilities [Member] | Undesignated Forward Loan Sale Commitments [Member]
Derivative [Line Items]
Derivative fair value, Liability	$ 263,000	$ 19,000

Minimum Regulatory Capital Re_3

Minimum Regulatory Capital Requirements - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Common equity tier 1 capital conservation buffer period	3 years
Common equity tier 1 capital conservation buffer with initial phase (as a percent)	1.875%	0.625%
Minimum [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Capital conservation buffer of common equity tier 1 capital to risk weighted assets ratio (as a percent)	2.50%

Minimum Regulatory Capital Re_4

Minimum Regulatory Capital Requirements - Summary of Actual and Minimum Capital Amounts and Ratios (Detail) - Bank [Member] - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Total capital (to risk weighted assets), actual amount	$ 72,523	$ 73,612
Tier 1 capital (to risk weighted assets), actual amount	68,086	69,875
Common equity Tier 1 capital (to risk weighted assets), actual amount	68,086	69,875
Tier 1 capital (to average assets), actual amount	$ 68,086	$ 69,875
Total capital (to risk weighted assets), actual ratio	16.10%	20.40%
Tier 1 capital (to risk weighted assets), actual ratio	15.10%	19.40%
Common equity Tier 1 capital (to risk weighted assets), actual ratio	15.10%	19.40%
Tier 1 capital (to average assets), actual ratio	10.90%	12.40%
Total capital (to risk weighted assets), for minimum capital adequacy purposes amount	$ 36,084	$ 28,896
Tier 1 capital (to risk weighted assets), for minimum capital adequacy purposes amount	27,063	21,667
Common equity Tier 1 capital (to risk weighted assets), for minimum capital adequacy amount	20,297	16,250
Common equity Tier 1 capital (to risk weighted assets), for minimum capital adequacy amount	$ 25,056	$ 22,564
Total capital (to risk weighted assets), for minimum capital adequacy purposes ratio	8.00%	8.00%
Tier 1 capital (to risk weighted assets), for minimum capital adequacy purposes ratio	6.00%	6.00%
Common equity Tier 1 capital (to risk weighted assets), for minimum capital adequacy purposes ratio	4.50%	4.50%
Tier 1 capital (to average assets), for minimum capital adequacy purposes ratio	4.00%	4.00%
Total capital (to risk weighted assets), minimum to be well capitalized under prompt corrective action provisions amount	$ 45,105	$ 36,120
Tier 1 capital (to risk weighted assets), minimum to be well capitalized under prompt corrective action provisions amount	36,084	28,889
Common equity Tier 1 capital (to risk weighted assets), minimum to be well capitalized under prompt corrective action provisions amount	29,318	23,472
Tier 1 capital (to average assets), minimum to be well capitalized under prompt corrective action provisions amount	$ 31,320	$ 28,205
Total capital (to risk weighted assets), minimum to be well capitalized under prompt corrective action provisions ratio	10.00%	10.00%
Tier 1 capital (to risk weighted assets), minimum to be well capitalized under prompt corrective action provisions ratio	8.00%	8.00%
Common equity Tier 1 capital (to risk weighted assets), minimum to be well capitalized under prompt corrective action provisions ratio	6.50%	6.50%
Tier 1 capital (to average assets), minimum to be well capitalized under prompt corrective action provisions ratio	5.00%	5.00%

Post-Retirement Plans - Additio

Post-Retirement Plans - Additional Information (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Other non-interest expense	$ 9,337,000	$ 7,427,000	$ 7,912,000	$ 6,998,000	$ 8,056,000	$ 7,202,000	$ 7,071,000	$ 6,962,000	$ 4,854,000	$ 4,075,000
Supplemental Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Accrued benefits	549,000				607,000				549,000	607,000
Other non-interest expense									58,000	64,000
Endorsement Split-Dollar Life Insurance Arrangements [Member]
Defined Benefit Plan Disclosure [Line Items]
Accrued benefits	$ 435,000				$ 419,000				435,000	419,000
Post-retirement benefit expense									$ 16,000	22,000
401(k) Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Description of employees eligibility									The Company maintains a 401(k) Plan whereby each employee reaching the age of 21 automatically becomes a participant in the plan. Employees may contribute up to 15% of their compensation subject to certain limits based on federal tax laws. All employees who have worked for one year or 1,000 hours are eligible for an automatic employer contribution of 3% of employees’ compensation, which includes no vesting period.
Minimum age of employee to become participant									21 years
Maximum annual contributions per employee, percent									15.00%
Minimum number of year worked by employees									1 year
Minimum number of hours worked by employees									1000 hours
Employer contribution percentage on employees compensation									3.00%
Automatic employer matching contributions vesting period									0 years
Employer matching contribution, percent									50.00%
Employer match of eligible employees contributions percentage									2.00%
Employer matching contributions vesting period									4 years
Contribution expense									$ 580,000	$ 583,000
401(k) Plan [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contribution percentage on employees compensation									4.00%

Post-Retirement Plans - Summary

Post-Retirement Plans - Summary of Information Pertaining to Activity in Plan (Details) - Supplemental Retirement Plan [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Change in plan assets:
Employer contributions	$ 201	$ 201
Benefits paid	(201)	(201)
Change in benefit obligation:
Benefit obligation at beginning of year	1,724	1,836
Service cost	10	10
Interest cost	48	53
Actuarial (gain) loss	(20)	26
Benefits paid	(201)	(201)
Benefit obligation at end of year	1,561	1,724
Unfunded status and accrued supplemental pension cost at year end	(1,561)	(1,724)
Accumulated benefit obligation at year end	$ 1,561	$ 1,724

Post-Retirement Plans - Summa_2

Post-Retirement Plans - Summary of Assumptions Used to Determine Benefit Obligation (Details) - Supplemental Retirement Plan [Member]	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.60%	2.90%
Annual inflation factor	1.00%	1.00%

Post-Retirement Plans - Summa_3

Post-Retirement Plans - Summary of Net Periodic Benefit Cost Included in Other Non-Interest Expenses Attributable to Plan (Details) - Supplemental Retirement Plan [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 10	$ 10
Interest cost	48	53
Amortization of net actuarial loss	41	38
Amortization of prior service credit	(89)	(89)
Net periodic benefit cost	$ 10	$ 12

Post-Retirement Plans - Summa_4

Post-Retirement Plans - Summary of Assumptions Used to Determine Net Periodic Benefit Cost (Details) - Supplemental Retirement Plan [Member]	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.90%	3.05%
Annual inflation factor	1.00%	1.00%

Post-Retirement Plans - Summa_5

Post-Retirement Plans - Summary of Estimated Future Benefit Payments Expected Future Services (Details) - Supplemental Retirement Plan [Member] $ in Thousands	Dec. 31, 2018USD ($)
Defined Benefit Plan Disclosure [Line Items]
2019	$ 201
2020	201
2021	201
2022	213
2023	334
2024-2028	$ 626

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options term	10 years	10 years
Stock-based compensation expense	$ 304,000	$ 65,000
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 493,000	$ 120,000
Minimum [Member] | Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options and awards vesting period	3 years	3 years
Maximum [Member] | Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options and awards vesting period	5 years	5 years
Two Thousand Seventeen Stock Option and Incentive Plan [Member] | Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved for issuance	586,872
Stock options term	10 years
Two Thousand Seventeen Stock Option and Incentive Plan [Member] | Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved for issuance	237,749
Two Thousand Seventeen Stock Option and Incentive Plan [Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options and awards vesting period	3 years
Two Thousand Seventeen Stock Option and Incentive Plan [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options and awards vesting period	5 years

Stock Based Compensation - Summ

Stock Based Compensation - Summary of Grants of Options to Purchase Shares of Common Stock (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted	27,000	340,387
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expiration period (years)	10 years	10 years
Expected volatility	29.87%
Expected volatility, minimum		23.59%
Expected volatility, maximum		29.87%
Expected life (years)	6 years 6 months
Risk free interest rate, minimum	2.68%	1.66%
Risk free interest rate, maximum	2.77%	2.06%
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Option fair value	$ 5.78	$ 2.71
Minimum [Member] | Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period (years)	3 years	3 years
Expected life (years)		3 years
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Option fair value	$ 5.83	$ 5.05
Maximum [Member] | Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period (years)	5 years	5 years
Expected life (years)		6 years 6 months

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Options Grants (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Stock Option Grants
Beginning Balance	316,009
Granted	27,000	340,387
Forfeited	(30,304)
Ending Balance	312,705	316,009
Exercisable at December 31, 2018	59,936
Unrecognized compensation cost (inclusive of directors' options)	$ 1,075,000
Weighted Average Exercise Price
Beginning Balance	$ 14.66
Granted	16.15
Forfeited	14.71
Ending Balance	14.78	$ 14.66
Exercisable at December 31, 2018	$ 14.66
Weighted Average Remaining Contractual Term and Aggregate Intrinsic Value
Weighted Average Remaining Contractual Term	8 years 8 months 23 days	9 years 9 months 10 days
Weighted Average Remaining Contractual Term, Granted	5 years 9 months 14 days
Weighted Average Remaining Contractual Term, Forfieted	6 years 5 months
Aggregate Intrinsic Value, Outstanding	$ 219,374
Aggregate Intrinsic Value, Outstanding		$ 219,374
Aggregate Intrinsic Value, Exercisable	$ 0
Stock Options [Member]
Stock Option Grants
Weighted average remaining recognition period (years)	3 years 7 months 13 days

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Activity in Restricted Stock Awards Under Equity Plan (Detail)	12 Months Ended
	Dec. 31, 2018USD ($)$ / sharesshares
Restricted Stock Awards
Beginning Balance | shares	176,239
Vested | shares	(33,835)
Forfeited | shares	(15,710)
Ending Balance | shares	126,694
Unrecognized compensation cost | $	$ 1,739,000
Weighted Average Grant Price
Beginning Balance | $ / shares	$ 14.66
Vested | $ / shares	14.66
Forfeited | $ / shares	14.66
Ending Balance | $ / shares	$ 14.66
Restricted Stock [Member]
Restricted Stock Awards
Weighted average remaining recognition period (years)	3 years 8 months 4 days

Employee Stock Ownership Plan -

Employee Stock Ownership Plan - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Employee Stock Ownership Plan E S O P Disclosures [Line Items]
Loan repaid term	25 years
Interest rate	4.50%	3.75%
Number of allocated shares	18,780
Annual allocation of shares, expiration year	2040
ESOP expense	$ 301,000	$ 286,000
Unallocated shares	413,158
Unallocated shares, value	$ 5,846,000
Common Stock [Member]
Employee Stock Ownership Plan E S O P Disclosures [Line Items]
Sale of stock, price per share	$ 10
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

Share Repurchase Program - Addi

Share Repurchase Program - Additional Information (Detail) - USD ($)	1 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017
Class Of Stock [Line Items]
Cost of shares repurchased		$ 1,716,000	$ 160,000
September 2017 Share Repurchase Program [Member]
Class Of Stock [Line Items]
Stock repurchase program percentage of outstanding shares repurchased	10.00%
Number of shares authorized to repurchase	586,854
Number of shares repurchased		117,877
Cost of shares repurchased		$ 1,832,000

Earnings (Loss) Per Share - Add

Earnings (Loss) Per Share - Additional Information (Detail) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Potentially dilutive common stock equivalents outstanding	0	0
Stock options outstanding	312,705	316,009

Earnings (Loss) Per Share - Sch

Earnings (Loss) Per Share - Schedule of Calculation of Average Number of Shares Outstanding Used to Calculate Basic and Diluted Earnings (Loss) Per Share (Detail) - shares	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Average number of common shares outstanding									5,994,373	5,902,981
Less: Average unallocated ESOP shares									(423,653)	(434,467)
Average number of common shares outstanding (basic and diluted)	5,526,416	5,567,596	5,580,683	5,603,886	5,597,762	5,429,564	5,425,033	5,420,356	5,570,720	5,468,514

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Future Minimum Rent Commitments (Detail) $ in Thousands	Dec. 31, 2018USD ($)
Operating Lease Liabilities Payments Due [Abstract]
2019	$ 1,027
2020	919
2021	743
2022	545
2023	114
Future minimum rent commitments,Leases	3,348
2019	(87)
2020	(89)
2021	(91)
2022	(94)
2023	(16)
Future minimum rent commitments,Sub-leases	(377)
2019	940
2020	830
2021	652
2022	451
2023	98
Future minimum rent commitments,Net	$ 2,971

Commitments and Contingencies_2

Commitments and Contingencies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018USD ($)Member	Dec. 31, 2017USD ($)
Commitments And Contingencies [Line Items]
Rent expense | $	$ 992,000	$ 883,000
Salary continuation term of employment arrangement	1 year
Senior Management [Member]
Commitments And Contingencies [Line Items]
Number of members with change in control agreements | Member	5
Change in control agreement description of terms	The company provide that if, within two years of a change of control of the Company or the Bank, the executive in involuntarily terminated other than for cause, disability or death, or voluntarily resigns for good reason, the executive will be entitled to a lump-sum payment equal to two times salary plus bonus, except for one executive where the payment is equal to one times salary plus bonus.
Minimum [Member]
Commitments And Contingencies [Line Items]
Lease options to extend the period	2 years
Maximum [Member]
Commitments And Contingencies [Line Items]
Lease options to extend the period	10 years

Commitments and Contingencies_3

Commitments and Contingencies - Summary of Financial Instruments Outstanding Contract Amounts Represent Credit Risk (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Commitments to Originate Loans [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Financial instruments with off-balance-sheet risk	$ 38,404	$ 35,549
Unused Lines and Letters of Credit [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Financial instruments with off-balance-sheet risk	45,977	39,968
Unadvanced Funds on Construction Loans [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Financial instruments with off-balance-sheet risk	14,175	6,967
Overdraft Lines of Credit [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Financial instruments with off-balance-sheet risk	$ 8,475	$ 8,996

Fair Value of Assets and Liab_3

Fair Value of Assets and Liabilities - Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value	$ 50,556	$ 61,576
Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value	50,038	61,043
Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value	518	533
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value	50,556	68,637
Fair value, Loans held for sale	38,474	30,452
Derivative assets	637	682
Derivative liabilities	263	47
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, Portfolio loans	3,680
Fair value, Loans held for sale	38,474	25,390
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	50,038	61,043
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	518	533
Fair Value, Measurements, Recurring [Member] | Derivative Loan Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	627	363
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	10	4
Derivative liabilities	263	19
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, Portfolio loans	3,680
Fair value, Loans held for sale	38,474	25,390
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	50,038	61,043
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	518	533
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Derivative Loan Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	627	363
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Forward Loan Sale Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	10	4
Derivative liabilities	$ 263	$ 19

Fair Value of Assets and Liab_4

Fair Value of Assets and Liabilities - Additional information (Detail)	3 Months Ended	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2018USD ($)Office	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, assets, level 1 to level 2 transfers, amount	$ 0	$ 0	$ 0
Fair value, assets, level 2 to level 1 transfers, amount	0	0	0
Fair value, liabilities, level 1 to level 2 transfers, amount	0	0	0
Fair value, liabilities, level 2 to level 1 transfers, amount	0	0	0
Increase in valuation allowance of mortgage servicing rights	200,000	334,000		$ 82,000
Impairment write-down of assets held for sale	$ 225,000	$ 166,000	225,000
Number of branches sold | Office		3
Gain on sale of building		$ 2,476,000
Branch Office [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment write-down of assets held for sale			$ 225,000
Gain on sale of building		$ 2,476,000
Measurement Input, Discount Rate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	0.13	0.12	0.13	0.14
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities measured at fair value on nonrecurring basis	$ 0	$ 0	$ 0

Fair Value of Assets and Liab_5

Fair Value of Assets and Liabilities - Schedule of Assets Measured at Fair Value on a Non-Recurring Basis (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage servicing rights, fair value	$ 8,554	$ 6,485
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gains (losses) on assets held, mortgage servicing rights	82	334
Gains (losses) on assets held for sale	2,476	(225)
Gains (losses) on assets held, foreclosed real estate	(36)
Gains (Losses) on assets held	2,522	109
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	7,786	6,397
Assets, Fair Value Disclosure	7,786	6,397
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	1,352	1,630
Fair value, Assets held for sale		828
Fair value, Foreclosed real estate	65	193
Assets, Fair Value Disclosure	$ 1,417	$ 2,651

Fair Value of Assets and Liab_6

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	Dec. 31, 2018	Dec. 31, 2017
Financial assets:
Securities available for sale	$ 50,556	$ 61,576
Level 2 [Member]
Financial assets:
Certificates of deposit	2,196	3,687
Securities available for sale	50,556	68,637
Loans held for sale	38,474	30,452
Derivative assets	637	682
Financial liabilities:
Deposits	435,964	350,979
FHLBB advances	88,894	38,531
Derivative liabilities	263	47
Level 3 [Member]
Financial assets:
Loans, net	473,612	331,132
Carrying Amount [Member]
Financial assets:
Certificates of deposit	2,205	3,675
Securities available for sale	50,556	68,637
Loans held for sale	38,474	30,452
Loans, net	483,846	332,991
Derivative assets	637	682
Financial liabilities:
Deposits	437,130	351,179
FHLBB advances	89,036	38,667
Derivative liabilities	263	47
Fair Value [Member]
Financial assets:
Certificates of deposit	2,196	3,687
Securities available for sale	50,556	68,637
Loans held for sale	38,474	30,452
Loans, net	473,612	331,132
Derivative assets	637	682
Financial liabilities:
Deposits	435,964	350,979
FHLBB advances	88,894	38,531
Derivative liabilities	$ 263	$ 47

Segment Information - Additiona

Segment Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018USD ($)SegmentOffice	Dec. 31, 2017USD ($)
Segment Reporting Information [Line Items]
Number of business segments | Segment	2
Number of branch offices | Office	5
Servicing fees amount	$ (1,264,000)	$ (1,473,000)
Envision Mortgage [Member]
Segment Reporting Information [Line Items]
Premium percentage for new loans	1.50%	1.50%
Premium income	$ 1,320,000	$ 897,000
Percentage of fees for HELOC	1.00%	1.00%
Servicing fees amount	$ (1,574,000)	$ (1,731,000)
Envision Bank [Member]
Segment Reporting Information [Line Items]
Percentage of loan servicing fees	0.14%	0.14%
Servicing fees amount	$ 310,000	$ 258,000

Segment Information - Summary o

Segment Information - Summary of Segment Information (Detail) - USD ($)		3 Months Ended								12 Months Ended
		Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Net interest income		$ 4,420,000	$ 4,260,000	$ 4,033,000	$ 3,982,000	$ 3,840,000	$ 3,816,000	$ 3,690,000	$ 3,484,000	$ 16,696,000	$ 14,830,000
Provision for loan losses		579,000	178,000	(90,000)	95,000	205,000		100,000	235,000	762,000	540,000
Net interest income after provision for loan losses										15,934,000	14,290,000
Non-interest income:
Customer service fees										1,464,000	1,455,000
Gain on loan origination and sale activities, net	[1]									8,859,000	10,047,000
Mortgage servicing fees, net										1,264,000	1,473,000
Gain on sales of buildings										2,476,000
Other										940,000	884,000
Total non-interest income										15,003,000	13,859,000
Non-interest expenses:
Salaries and employee benefits										19,765,000	18,731,000
Occupancy and equipment										2,873,000	2,655,000
Restructuring charges		875,000				594,000				968,000	594,000
Merger and integration costs							7,000	357,000	167,000		531,000
Other non-interest expenses										8,066,000	7,311,000
Total non-interest expenses		9,337,000	7,427,000	7,912,000	6,998,000	8,056,000	7,209,000	7,428,000	7,129,000	31,672,000	29,822,000
Income (loss) before income taxes and elimination of inter-segment profit										(735,000)	(1,673,000)
Elimination of inter-segment profit										(1,320,000)	(896,000)
Loss before income taxes										(2,055,000)	(2,569,000)
Income tax expense (benefit)		17,000	5,000	4,000	4,000	(295,000)	129,000	(254,000)	(23,000)	31,000	(443,000)
Net income (loss)		(228,000)	$ (142,000)	$ (1,010,000)	$ (707,000)	(1,578,000)	$ 49,000	$ (150,000)	$ (447,000)	(2,086,000)	(2,126,000)
Total assets, December 31, 2018		614,340,000				531,892,000				614,340,000	531,892,000
Envision Bank [Member]
Segment Reporting Information [Line Items]
Net interest income										15,664,000	13,827,000
Provision for loan losses										762,000	540,000
Net interest income after provision for loan losses										14,902,000	13,287,000
Non-interest income:
Customer service fees										1,344,000	1,355,000
Mortgage servicing fees, net										(310,000)	(258,000)
Gain on sales of buildings										2,476,000
Other										520,000	408,000
Total non-interest income										4,030,000	1,505,000
Non-interest expenses:
Salaries and employee benefits										6,793,000	6,243,000
Occupancy and equipment										1,507,000	1,392,000
Merger and integration costs											19,000
Other non-interest expenses										4,476,000	3,955,000
Total non-interest expenses										12,776,000	11,609,000
Income (loss) before income taxes and elimination of inter-segment profit										6,156,000	3,183,000
Total assets, December 31, 2018		526,871,000				468,515,000				526,871,000	468,515,000
Envision Mortgage [Member]
Segment Reporting Information [Line Items]
Net interest income										1,032,000	1,003,000
Net interest income after provision for loan losses										1,032,000	1,003,000
Non-interest income:
Customer service fees										120,000	100,000
Gain on loan origination and sale activities, net	[1]									8,859,000	10,047,000
Mortgage servicing fees, net										1,574,000	1,731,000
Other										420,000	476,000
Total non-interest income										10,973,000	12,354,000
Non-interest expenses:
Salaries and employee benefits										12,972,000	12,488,000
Occupancy and equipment										1,366,000	1,263,000
Restructuring charges										968,000	594,000
Merger and integration costs											512,000
Other non-interest expenses										3,590,000	3,356,000
Total non-interest expenses										18,896,000	18,213,000
Income (loss) before income taxes and elimination of inter-segment profit										(6,891,000)	(4,856,000)
Total assets, December 31, 2018		$ 87,469,000				$ 63,377,000				$ 87,469,000	$ 63,377,000
[1]	Before elimination of inter-segment profit

Other Non-Interest Expenses - A

Other Non-Interest Expenses - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Other Income And Expenses [Abstract]
Percentage of certain items exceeding interest and non interest income	1.00%	1.00%

Other Non-Interest Expenses - S

Other Non-Interest Expenses - Schedule of Company's Total Interest and Non-Interest Income Included in Other Non-Interest Expenses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Other Income And Expenses [Abstract]
Software amortization and maintenance	$ 754	$ 789
Card related expenses	470	359
Data communication and telephone	495	463
Directors fees, including stock-based compensation	$ 613	$ 407

Restructuring Charges - Additio

Restructuring Charges - Additional Information (Detail)	3 Months Ended		12 Months Ended
	Dec. 31, 2018USD ($)ft²PositionEmployee	Dec. 31, 2017USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Restructuring Cost And Reserve [Line Items]
Percentage of workforce reduction		8.00%
Restructuring charges	$ 875,000	$ 594,000	$ 968,000	$ 594,000
Impairment write-down on furniture and equipment		$ 225,000	166,000	$ 225,000
Consolidation of Mortgage Banking Operations [Member]
Restructuring Cost And Reserve [Line Items]
Impairment write-down on furniture and equipment	$ 168,000
Consolidation of Mortgage Banking Operations [Member] | Andover [Member]
Restructuring Cost And Reserve [Line Items]
Number of administrative positions eliminated | Position	15
Number of employees remained | Employee	25
Severance costs			235,000
Remaining space available | ft²	4,200
Fair value, Cease use liability	$ 565,000		$ 565,000
Consolidation of Mortgage Banking Operations [Member] | North Attleboro [Member]
Restructuring Cost And Reserve [Line Items]
Number of administrative positions to be added | Position	8

Parent Company Condensed Fina_3

Parent Company Condensed Financial Statements - Balance Sheets (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets
Cash and due from banks	$ 3,451	$ 3,562
Total assets	614,340	531,892
Liabilities
Total liabilities	536,379	450,409
Stockholders' Equity:
Common stock	60	61
Additional paid-in capital	55,608	56,493
Retained earnings	28,329	30,415
ESOP-Unearned compensation	(4,132)	(4,319)
Accumulated other comprehensive loss, net of tax	(1,904)	(1,167)
Total stockholders' equity	77,961	81,483	$ 83,302
Total liabilities and stockholders' equity	614,340	531,892
Randolph Bancorp, Inc. and Predecessor Randolph Bancorp [Member]
Assets
Cash and due from banks	6,850	8,187
Due from Envision Bank		141
Investment in Envision Bank	66,971	68,777
ESOP loan	4,266	4,378
Total assets	78,087	81,483
Liabilities
Accounts payable	70
Due to Envision Bank	56
Total liabilities	126
Stockholders' Equity:
Common stock	60	61
Additional paid-in capital	55,608	56,493
Retained earnings	28,329	30,415
ESOP-Unearned compensation	(4,132)	(4,319)
Accumulated other comprehensive loss, net of tax	(1,904)	(1,167)
Total stockholders' equity	77,961	81,483
Total liabilities and stockholders' equity	$ 78,087	$ 81,483

Parent Company Condensed Fina_4

Parent Company Condensed Financial Statements - Statements of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Condensed Income Statements Captions [Line Items]
Interest income	$ 6,050	$ 5,468	$ 5,039	$ 4,727	$ 4,492	$ 4,389	$ 4,175	$ 3,884	$ 21,284	$ 16,940
Income tax expense (benefit)	17	5	4	4	(295)	129	(254)	(23)	31	(443)
Net income (loss)	$ (228)	$ (142)	$ (1,010)	$ (707)	$ (1,578)	$ 49	$ (150)	$ (447)	(2,086)	(2,126)
Randolph Bancorp, Inc. and Predecessor Randolph Bancorp [Member]
Condensed Income Statements Captions [Line Items]
Interest income									197	169
Operating expenses									197	308
Loss before incomes taxes and equity in undistributed net loss of Envision Bank										(139)
Loss before equity in undistributed net loss of Envision Bank										(139)
Equity in undistributed net loss of Envision Bank									(2,086)	(1,987)
Net income (loss)									$ (2,086)	$ (2,126)

Parent Company Condensed Fina_5

Parent Company Condensed Financial Statements - Statements of Cash Flows (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net loss	$ (2,086)	$ (2,126)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Net cash provided by (used in) operating activities	(11,291)	5,910
Cash flows from investing activities:
Net cash used in investing activities	(73,365)	(64,056)
Cash flows from financing activities:
Stock repurchases	(1,716)	(160)
Stock repurchase payable	70
Net cash provided by financing activities	82,952	52,119
Net change in cash and cash equivalents	(1,704)	(6,027)
Cash and cash equivalents at beginning of year	8,822	14,849
Cash and cash equivalents at end of year	7,118	8,822
Randolph Bancorp, Inc. and Predecessor Randolph Bancorp [Member]
Cash flows from operating activities:
Net loss	(2,086)	(2,126)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Equity in undistributed net loss of Envision Bank	2,086	1,987
Change in intercompany receivable/payable	197	(139)
Net cash provided by (used in) operating activities	197	(278)
Cash flows from investing activities:
Payments received on ESOP loan	112	129
Net cash used in investing activities	112	129
Cash flows from financing activities:
Stock repurchases	(1,716)	(160)
Stock repurchase payable	70
Net cash provided by financing activities	(1,646)	(160)
Net change in cash and cash equivalents	(1,337)	(309)
Cash and cash equivalents at beginning of year	8,187	8,496
Cash and cash equivalents at end of year	$ 6,850	$ 8,187

Selected Quarterly Financial _3

Selected Quarterly Financial Data (Unaudited) - Summary of Selected Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Interest and dividend income	$ 6,050	$ 5,468	$ 5,039	$ 4,727	$ 4,492	$ 4,389	$ 4,175	$ 3,884	$ 21,284	$ 16,940
Interest expense	1,630	1,208	1,006	745	652	573	485	400	4,588	2,110
Net interest income	4,420	4,260	4,033	3,982	3,840	3,816	3,690	3,484	16,696	14,830
Provision (credit) for loan losses	579	178	(90)	95	205		100	235	762	540
Gain on loan origination and sales activities, net	2,183	1,956	1,854	1,547	1,888	2,705	2,520	2,038
Other non-interest income	3,102	1,252	929	861	660	866	914	1,372	733	731
Total non-interest income	5,285	3,208	2,783	2,408	2,548	3,571	3,434	3,410	13,683	12,963
Merger and integration costs						7	357	167		531
Other non-interest expense	9,337	7,427	7,912	6,998	8,056	7,202	7,071	6,962	4,854	4,075
Total non-interest expenses	9,337	7,427	7,912	6,998	8,056	7,209	7,428	7,129	31,672	29,822
Provision (benefit) for income taxes	17	5	4	4	(295)	129	(254)	(23)	31	(443)
Net income (loss)	$ (228)	$ (142)	$ (1,010)	$ (707)	$ (1,578)	$ 49	$ (150)	$ (447)	$ (2,086)	$ (2,126)
Basic and diluted earnings (loss) per share	$ (0.04)	$ (0.03)	$ (0.18)	$ (0.13)	$ (0.28)	$ 0.01	$ (0.03)	$ (0.08)	$ (0.37)	$ (0.39)
Weighted average common shares (basic and diluted)	5,526,416	5,567,596	5,580,683	5,603,886	5,597,762	5,429,564	5,425,033	5,420,356	5,570,720	5,468,514

Selected Quarterly Financial _4

Selected Quarterly Financial Data (Unaudited) - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effect Of Fourth Quarter Events [Line Items]
Restructuring charges	$ 875,000	$ 594,000	$ 968,000	$ 594,000
Impairment write-down of assets held for sale		225,000	166,000	$ 225,000
Reduction of valuation allowance for mortgage servicing rights		200,000	$ 334,000		$ 82,000
Expenses for planned transfer of loan servicing		160,000
Tax benefit due to repeal of AMT		$ 462,000
Boston Branch Location [Member]
Effect Of Fourth Quarter Events [Line Items]
Gain recognized on sale of former branch location	$ 2,261,000