BankFinancial (BFIN) 10-K 23 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Feb. 09, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2,017
Entity Registrant Name	BankFinancial CORP
Entity Central Index Key	1,303,942
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		17,932,223
Entity Well-known Seasoned Issuer	No
Entity Public Float			$ 227.7
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No

Consolidated Statements of Fina

Consolidated Statements of Financial Condition - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets
Cash and due from other financial institutions	$ 13,572	$ 13,053
Interest-bearing deposits in other financial institutions	114,020	83,631
Cash and cash equivalents	127,592	96,684
Securities, at fair value	93,383	107,212
Loans receivable, net of allowance for loan losses	1,314,651	1,312,952
Other real estate owned, net	2,351	3,895
Stock in Federal Home Loan Bank, at cost	8,290	11,650
Premises held-for-sale	5,667	0
Premises and equipment, net	24,856	31,413
Accrued interest receivable	4,619	4,381
Core deposit intangible	286	782
Bank owned life insurance	22,859	22,594
Deferred Tax Assets, Net	12,563	22,411
Other assets	8,441	6,063
Total assets	1,625,558	1,620,037
Deposits
Noninterest-bearing	234,354	249,539
Interest-bearing	1,105,697	1,089,851
Total deposits	1,340,051	1,339,390
Borrowings	60,768	51,069
Advance payments by borrowers taxes and insurance	11,645	11,041
Accrued interest payable and other liabilities	15,460	13,757
Total liabilities	1,427,924	1,415,257
Commitments and contingent liabilities
Stockholders' equity:
Preferred Stock, $0.01 par value, 25,000,000 shares authorized, none issued or outstanding	0	0
Common Stock, $0.01 par value, 100,000,000 shares authorized; 17,958,723 shares issued at December 31, 2017 and 19,233,760 shares issued at December 31, 2016	179	192
Additional paid-in capital	153,811	173,047
Retained earnings	43,274	39,483
Unearned Employee Stock Ownership Plan shares	0	(8,318)
Accumulated other comprehensive income	370	376
Total stockholders' equity	197,634	204,780
Total liabilities and stockholders' equity	$ 1,625,558	$ 1,620,037

Consolidated Statements of Fin3

Consolidated Statements of Financial Condition (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Allowance for loan losses	$ 8,366	$ 8,127
Preferred Stock, par value (usd per share)	$ 0.01	$ 0.01
Preferred Stock, shares authorized	25,000,000	25,000,000
Preferred Stock, shares issued	0	0
Preferred Stock, shares outstanding	0	0
Common Stock, par value (usd per share)	$ 0.01	$ 0.01
Common Stock, shares authorized	100,000,000	100,000,000
Common Stock, shares issued	17,958,723	19,233,760

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest and dividend income
Loans, including fees	$ 53,227	$ 49,025	$ 47,488
Securities	1,474	1,228	1,141
Other	1,478	675	333
Total interest income	56,179	50,928	48,962
Interest expense
Deposits	5,438	3,865	2,794
Borrowings	651	105	20
Total interest expense	6,089	3,970	2,814
Net interest income	50,090	46,958	46,148
Provision for (recovery of) loan losses	(87)	(239)	(3,206)
Net interest income	50,177	47,197	49,354
Noninterest income
Deposit service charges and fees	2,250	2,254	2,248
Other fee income	2,029	2,052	2,143
Insurance commissions and annuities income	251	302	386
Gain on sale of loans, net	76	75	102
Gain on sale of securities (includes $46 accumulated other comprehensive income reclassifications for unrealized net gains on available for sale securities for the year ended December 31, 2016)	0	46	0
Loan servicing fees	248	276	354
Amortization and impairment of servicing assets	(109)	(112)	(140)
Earnings on bank owned life insurance	265	207	194
Trust	720	674	712
Other	678	771	692
Total noninterest income	6,408	6,545	6,691
Noninterest expense
Compensation and benefits	21,767	22,755	22,222
Office occupancy and equipment	6,623	6,380	6,522
Advertising and public relations	1,004	870	991
Information technology	2,743	2,892	2,669
Supplies, telephone, and postage	1,366	1,364	1,586
Amortization of intangibles	496	523	550
Nonperforming asset management	340	399	681
Operations of other real estate owned	923	846	1,063
FDIC insurance premiums	587	755	904
Other	4,542	4,758	4,757
Total noninterest expense	40,391	41,542	41,945
Income (loss) before income taxes	16,194	12,200	14,100
Income tax expense	7,190	4,698	5,425
Net income (loss)	$ 9,004	$ 7,502	$ 8,675
Basic earnings (loss) per common share (usd per share)	$ 0.49	$ 0.40	$ 0.44
Diluted earnings (loss) per common share (usd per share)	$ 0.49	$ 0.39	$ 0.44
Weighted average common shares outstanding (shares)	18,279,899	18,987,951	19,918,003
Diluted weighted average common shares outstanding (shares)	18,280,336	19,047,139	19,921,519

Consolidated Statements of Ope5

Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Reclassification adjustment for unrealized net gains (losses) on available for sale securities	$ 0	$ 46	$ 0

Consolidated Statements Compreh

Consolidated Statements Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 9,004	$ 7,502	$ 8,675
Unrealized holding loss on securities arising during the period	(102)	(233)	(339)
Tax effect	36	90	129
Net of tax	(66)	(143)	(210)
Reclassification adjustment for gain included in net income	0	(46)	0
Tax effect, included in income tax expense	0	18	0
Reclassification adjustment for (gain) included in net income, net of tax	0	(28)	0
Other comprehensive loss	(66)	(171)	(210)
Comprehensive income	$ 8,938	$ 7,331	$ 8,465

Consolidated Statements of Chan

Consolidated Statements of Changes In Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Unearned Employee Stock Ownership Plan Shares	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Dec. 31, 2014	$ 216,121	$ 211	$ 193,845	$ 31,584	$ (10,276)	$ 757
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	8,675	0	0	8,675	0	0
Other comprehensive loss, net of tax effect	(210)	0	0	0	0	(210)
Prepayment of ESOP Share Acquisition Loan	0
Nonvested stock awards-stock-based compensation expense	657	0	657	0	0	0
Repurchase and retirement of common stock	(9,970)	(8)	(9,962)	0	0	0
Cash dividends declared on common stock	(4,145)	0	0	(4,145)	0	0
ESOP shares earned	1,236	0	257	0	979	0
Ending Balance at Dec. 31, 2015	212,364	203	184,797	36,114	(9,297)	547
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	7,502	0	0	7,502	0	0
Other comprehensive loss, net of tax effect	(171)	0	0	0	0	(171)
Prepayment of ESOP Share Acquisition Loan	0
Nonvested stock awards-stock-based compensation expense	982	0	982	0	0	0
Repurchase and retirement of common stock	(13,215)	(11)	(13,204)	0	0	0
Cash dividends declared on common stock	(4,133)	0	0	(4,133)	0	0
ESOP shares earned	1,451	0	472	0	979	0
Ending Balance at Dec. 31, 2016	204,780	192	173,047	39,483	(8,318)	376
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	9,004	0	0	9,004	0	0
Other comprehensive loss, net of tax effect	(66)	0	0	0	0	(66)
Reclassification for the Tax Cuts and Jobs Act	0	0	0	(60)	0	60
Net exercise of stock options (198,026 shares)	(1,237)	2	(1,239)	0	0	0
Prepayment of ESOP Share Acquisition Loan	1,125	(8)	(7,185)	0	8,318	0
Repurchase and retirement of common stock	(10,819)	(7)	(10,812)	0	0	0
Cash dividends declared on common stock	(5,153)	0	0	(5,153)	0	0
Ending Balance at Dec. 31, 2017	$ 197,634	$ 179	$ 153,811	$ 43,274	$ 0	$ 370

Consolidated Statements of Cha8

Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Purchase and retirement of common stock (shares)	719,573	1,063,557	804,469
Cash dividends declared on common stock (usd per share)	$ 0.28	$ 0.21	$ 0.20
Share-based compensation arrangement by share-based payment award, options, exercisable, number (in shares)	198,026

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities
Net income	$ 9,004,000	$ 7,502,000	$ 8,675,000
Adjustments to reconcile to net loss to net cash from operating activities
Provision for (recovery of) loan losses	(87,000)	(239,000)	(3,206,000)
Prepayment of ESOP Share Acquisition Loan	1,125,000	0	0
ESOP shares earned	0	1,451,000	1,236,000
Stock-based compensation expense	0	982,000	657,000
Depreciation and amortization	3,789,000	3,777,000	3,682,000
Amortization and accretion on securities and loans	(123,000)	(280,000)	(312,000)
Amortization of core deposit and other intangible assets	496,000	523,000	550,000
Amortization and impairment of servicing assets	109,000	112,000	140,000
Net change in net deferred loan origination costs	397,000	(42,000)	(422,000)
Net loss on sale of other real estate owned	45,000	(128,000)	(59,000)
Net gain on sale of loans	(76,000)	(75,000)	(102,000)
Net gain on sale of securities	0	(46,000)	0
Net (gain) loss on disposition of premises and equipment	0	(38,000)	1,000
Loans originated for sale	(1,288,000)	(2,310,000)	(3,838,000)
Proceeds from sale of loans	1,364,000	2,385,000	3,940,000
Other real estate owned valuation adjustments	333,000	314,000	548,000
Net change in:
Deferred income tax	9,848,000	4,390,000	5,079,000
Accrued interest receivable	(238,000)	(155,000)	(300,000)
Earnings on bank owned life insurance	(265,000)	(207,000)	(194,000)
Other assets	(3,406,000)	(1,418,000)	659,000
Accrued interest payable and other liabilities	1,703,000	2,443,000	(1,852,000)
Net Cash Provided by (Used in) Operating Activities	22,730,000	18,941,000	14,882,000
Securities
Proceeds from maturities	75,460,000	67,734,000	59,804,000
Proceeds from principal repayments	3,388,000	5,102,000	6,984,000
Proceeds from sales of securities	0	46,000	0
Purchases of securities	(65,128,000)	(65,617,000)	(60,744,000)
Loans receivable
Loan participations sold	3,615,000	6,195,000	3,350,000
Principal payments on loans receivable	654,702,000	495,391,000	441,820,000
Purchases of loans	(23,451,000)	(54,970,000)	0
Originated for investment	(640,340,000)	(543,740,000)	(509,018,000)
Proceeds from sale of loans	0	14,746,000	0
Payments for (Proceeds from) Federal Home Loan Bank Stock	(3,514,000)	0	0
Purchase of Federal Home Loan Bank and Federal Reserve Bank stock	(154,000)	(5,393,000)	0
Proceeds from sale of other real estate owned	3,932,000	4,181,000	4,733,000
Purchases of premises and equipment, net	(1,133,000)	(696,000)	(542,000)
Net cash from (used in) investing activities	14,405,000	(77,021,000)	(53,613,000)
Cash flows from financing activities
Net change in deposits	661,000	126,471,000	1,206,000
Net change in borrowings	9,699,000	(13,249,000)	51,397,000
Net change in advance payments by borrowers for taxes and insurance	604,000	(487,000)	39,000
Repurchase and retirement of common stock	(10,819,000)	(13,215,000)	(9,970,000)
Cash dividends paid on common stock	(5,153,000)	(4,133,000)	(4,145,000)
Shares retired for tax liability	(1,219,000)	0	0
Net cash used in financing activities	(6,227,000)	95,387,000	38,527,000
Net change in cash and cash equivalents	30,908,000	37,307,000	(204,000)
Beginning cash and cash equivalents	96,684,000	59,377,000	59,581,000
Ending cash and cash equivalents	127,592,000	96,684,000	59,377,000
Supplemental disclosures of cash flow information:
Interest paid	6,044,000	3,907,000	2,844,000
Income taxes paid	427,000	289,000	363,000
Income taxes refunded	6,000	9,000	7,000
Loans transferred to other real estate owned	2,766,000	1,251,000	5,875,000
Transfer of Property to Held-for-sale	$ 5,667,000	$ 0	$ 0

Summary of Significant Accounti

Summary of Significant Accounting Policies (Notes)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Significant Accounting Policies	Basis of Presentation : BankFinancial Corporation, a Maryland corporation headquartered in Burr Ridge, Illinois (the “Company”), is the owner of all of the issued and outstanding capital stock of BankFinancial, National Association (the “Bank”). BankFinancial Corporation is a registered Bank Holding Company and its wholly-owned bank subsidiary is operating as BankFinancial, National Association. Principles of Consolidation : The consolidated financial statements include the accounts of and transactions of BankFinancial Corporation, the Bank, and the Bank’s wholly-owned subsidiaries, Financial Assurance Services, Inc. and BFIN Asset Recovery Company, LLC (formerly BF Asset Recovery Corporation) (collectively, “the Company”) and have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). All significant intercompany accounts and transactions have been eliminated. Nature of Business : The Company’s revenues, operating income, and assets are primarily from the banking industry. Loan origination customers are mainly located in the greater Chicago metropolitan area. To supplement loan originations, the Company purchases mortgage loans. The loan portfolio is concentrated in loans that are primarily secured by real estate. Use of Estimates : To prepare financial statements in conformity with GAAP, management makes estimates and assumptions based on available information. These estimates and assumptions affect the amounts reported in the financial statements and the disclosures provided, and actual results could differ. Interest-bearing Deposits in Other Financial Institutions : Interest-bearing deposits in other financial institutions maturing in less than 90 days are carried at cost. Cash Flows : Cash and cash equivalents include cash, deposits with other financial institutions maturing in less than 90 days, and daily federal funds sold. Net cash flows are reported for customer loan and deposit transactions, interest bearing deposits in other financial institutions, borrowings, and advance payments by borrowers for taxes and insurance. Securities : Debt securities are classified as available-for-sale when they might be sold before maturity. Equity securities with readily determinable fair values are classified as available-for-sale. Securities available-for-sale are carried at fair value, with unrealized holding gains and losses reported in other comprehensive income (loss), net of tax. Interest income includes amortization of purchase premium or discount. Premiums and discounts on securities are amortized on the level-yield method without anticipating prepayments, except for mortgage-backed securities where prepayments are anticipated. Gains and losses on sales are based on the amortized cost of the security sold. Declines in the fair value of securities below their cost that are other-than-temporary are reflected as realized losses. In determining if losses are other-than-temporary, management considers: (1) the length of time and extent that fair value has been less than cost or adjusted cost, as applicable, (2) the financial condition and near term prospects of the issuer, and (3) whether the Company has the intent to sell the debt security or it is more likely than not that the Company will be required to sell the debt security before the anticipated recovery. Securities also include investments in certificates of deposit with maturities of greater than 90 days. These certificates of deposit are placed with insured institutions for varying maturities and amounts that are fully insured by the Federal Deposit Insurance Corporation (“FDIC”). Federal Home Loan Bank (“FHLB”) Stock : The Bank is a member of the FHLB system. Members are required to own a certain amount of stock based on the level of borrowings and other factors, and may invest in additional amounts. FHLB stock is carried at cost, classified as a restricted security, and periodically evaluated for impairment based on ultimate recovery of par value. Both cash and stock dividends are reported as income. Federal Reserve Bank (“FRB”) Stock : The Bank is a member of its regional Federal Reserve Bank. FRB stock is carried at cost, classified as a restricted security, and periodically evaluated for impairment based on ultimate recovery of par value. Both cash and stock dividends are reported as income. Loans and Loan Income : Loans that management has the intent and ability to hold for the foreseeable future or until maturity or payoff are reported at the principal balance outstanding, net of the allowance for loan losses, premiums and discounts on loans purchased, and net deferred loan costs. Interest income on loans is recognized in income over the term of the loan based on the amount of principal outstanding. Premiums and discounts associated with loans purchased are amortized over the contractual term of the loan using the level–yield method. Loan origination fees, net of certain direct origination costs, are deferred and recognized in interest income using the level‑yield method without anticipating prepayments. Interest income is reported on the interest method. Interest income is discontinued at the time a loan is 90 days past due or when we do not expect to receive full payment of interest or principal. Past due status is based on the contractual terms of the loan. All interest accrued but not received for loans that have been placed on nonaccrual status is reversed against interest income. Interest received on such loans is accounted for on the cash–basis or cost–recovery method until qualifying for return to accrual status. Once a loan is placed on nonaccrual status, the borrower must generally demonstrate at least six months of payment performance before the loan is eligible to return to accrual status. Generally, the Company utilizes the “90 days delinquent, still accruing” category of loan classification when: (1) the loan is repaid in full shortly after the period end date; (2) the loan is well secured and there are no asserted or pending legal barriers to its collection; or (3) the borrower has remitted all scheduled payments and is otherwise in substantial compliance with the terms of the loan, but the processing of payments actually received or the renewal of a loan has not occurred for administrative reasons. Impaired Loans: Impaired loans consist of nonaccrual loans and troubled debt restructurings (“TDRs”). A loan is considered impaired when, based on current information and events, management believes that it is probable that we will be unable to collect all amounts due (both principal and interest) according to the original contractual terms of the loan agreement. Once a loan is determined to be impaired, the amount of impairment is measured based on the loan's observable fair value, the fair value of the underlying collateral less selling costs if the loan is collateral-dependent, or the present value of expected future cash flows discounted at the loan's effective interest rate. If the measurement of the impaired loan is less than the recorded investment in the loan, the bank's allowance for the impaired collateral dependent loan under ASC 310-10-35 is based on fair value (less costs to sell), but the charge-off (the confirmed “loss”) is based on the appraised value. The remaining recorded investment in the loan after the charge-off will have a loan loss allowance for the amount by which the estimated fair value of the collateral (less costs to sell) is less than its appraised value. Impaired loans with specific reserves are reviewed quarterly for any changes that would affect the specific reserve. Any impaired loan for which a determination has been made that the economic value is permanently reduced is charged-off against the allowance for loan losses to reflect its current economic value in the period in which the determination has been made. At the time a collateral-dependent loan is initially determined to be impaired, we review the existing collateral appraisal. If the most recent appraisal is greater than a year old, a new appraisal is obtained on the underlying collateral. Appraisals are updated with a new independent appraisal at least annually and are formally reviewed by our internal appraisal department upon receipt of a new appraisal. All impaired loans and their related reserves are reviewed and updated each quarter. With an immaterial number of exceptions, all appraisals and internal reviews are current under this methodology at December 31, 2017 . Troubled Debt Restructurings : A loan is classified as a troubled debt restructuring when a borrower is experiencing financial difficulties that leads to a restructuring of the loan, and the Company grants concessions to the borrower in the restructuring that it would not otherwise consider. These concessions may include rate reductions, principal forgiveness, extension of maturity date and other actions intended to minimize potential losses. In determining whether a debtor is experiencing financial difficulties, the Company considers if the debtor is in payment default or would be in payment default in the foreseeable future without the modification, the debtor declared or is in the process of declaring bankruptcy, there is substantial doubt that the debtor will continue as a going concern, the debtor has securities that have been or are in the process of being delisted, the debtor's entity-specific projected cash flows will not be sufficient to service any of its debt, or the debtor cannot obtain funds from sources other than the existing creditors at a market rate for debt with similar risk characteristics. In determining whether the Company has granted a concession, the Company assesses, if it does not expect to collect all amounts due, whether the current value of the collateral will satisfy the amounts owed, whether additional collateral or guarantees from the debtor will serve as adequate compensation for other terms of the restructuring, and whether the debtor otherwise has access to funds at a market rate for debt with similar risk characteristics. Periodically, the Company will restructure a note into two separate notes (A/B structure), charging off the entire B portion of the note. The A note is structured with appropriate loan-to-value and cash flow coverage ratios that provide for a high likelihood of repayment. The A note is classified as a nonperforming note until the borrower has displayed a historical payment performance for a reasonable time prior to and subsequent to the restructuring. A period of sustained repayment for at least six months generally is required to return the note to accrual status provided that management has determined that the performance is reasonably expected to continue. The A note will be classified as a restructured note (either performing or nonperforming) through the calendar year of the restructuring that the historical payment performance has been established. Allowance for Loan Losses: The Company establishes provisions for loan losses, which are charged to the Company’s results of operations to maintain the allowance for loan losses to absorb probable incurred credit losses in the loan portfolio. In determining the level of the allowance for loan losses, the Company considers past and current loss experience, trends in classified loans, evaluations of real estate collateral, current economic conditions, volume and type of lending, adverse situations that may affect a borrower’s ability to repay a loan and the levels of nonperforming and other classified loans. The amount of the allowance is based on estimates and the ultimate losses may vary from the estimates as more information becomes available or events change. The Company provides for loan losses based on the allowance method. Accordingly, all loan losses are charged to the related allowance and all recoveries are credited to it. Additions to the allowance for loan losses are provided by charges to income based on various factors that, in our judgment, deserve current recognition in estimating probable incurred credit losses. The Company reviews the loan portfolio on an ongoing basis and makes provisions for loan losses on a quarterly basis to maintain the allowance for loan losses in accordance with GAAP. The allowance for loan losses consists of two components: • specific allowances established for any impaired residential non-owner occupied mortgage, multi-family mortgage, nonresidential real estate, construction and land, commercial, and commercial lease loans for which the recorded investment in the loan exceeds the measured value of the loan; and • general allowances for loan losses for each loan class based on historical loan loss experience; and adjustments to historical loss experience (general allowances), maintained to cover uncertainties that affect our estimate of probable incurred credit losses for each loan class. The adjustments to historical loss experience are based on our evaluation of several factors, including levels of, and trends in, past due and classified loans; levels of, and trends in, charge–offs and recoveries; trends in volume and terms of loans, including any credit concentrations in the loan portfolio; experience and ability of lending management and other relevant staff; and national and local economic trends and conditions. The Company evaluates the allowance for loan losses based upon the combined total of the specific and general components. Generally, when the loan portfolio increases, absent other factors, the allowance for loan loss methodology results in a higher dollar amount of estimated probable incurred credit losses than would be the case without the increase. Conversely, when the loan portfolio decreases, absent other factors, the allowance for loan loss methodology generally results in a lower dollar amount of estimated probable losses than would be the case without the decrease. The loss ratio used in computing the required general loan loss reserve allowance for a given class of loan consists of (i) the actual loss ratio (measured on a weighted, rolling twelve-quarter basis), (ii) the change in credit quality within the specific loan class during the period, (iii) the actual inherent risk factor assigned to the specific loan class and (iv) the actual concentration of risk factor assigned to the specific loan class (collectively, the “Specific Loan Class Risk Factors”). The Specific Loan Class Risk Factors are weighted equally in the calculation. In addition, two additional quantitative factors, the National Economic risk factor and the Local Economic risk factor, are also components of the computation but are given different weightings in their computation due to their relative applicability to the specific loan class in the context of the effect of national and local economic conditions on their risk profile and performance. Mortgage Servicing Rights : Mortgage servicing rights are recognized separately when they are acquired through sales of loans. When mortgage loans are sold, servicing rights are initially recorded at fair value and gains on sales of loans are recorded in the statement of operations. Fair value is based on market prices for comparable mortgage servicing contracts, when available, or alternatively, is based on a valuation model that calculates the present value of estimated future net servicing income. The valuation model incorporates assumptions that market participants would use in estimating future net servicing income, such as the servicing cost per loan, the discount rate, the escrow float rate, an inflation rate, ancillary income, prepayment speeds and default rates and losses. The Company compares the valuation model inputs and results to published industry data in order to validate the model results and assumptions. All classes of servicing assets are subsequently measured using the amortization method which requires servicing rights to be amortized into noninterest income in proportion to, and over the period of, the estimated future net servicing income of the underlying loans. Servicing assets are evaluated for impairment based upon the fair value of the rights as compared to carrying amount. Impairment is determined by stratifying rights into groupings based on predominant risk characteristics, such as interest rate, loan type and investor type. Impairment is recognized through a valuation allowance for an individual grouping, to the extent that fair value is less than the carrying amount. If the Company later determines that all or a portion of the impairment no longer exists for a particular grouping, a reduction of the allowance may be recorded as an increase to income. Changes in valuation allowances are reported with amortization and impairment of servicing assets on the statement of operations. The fair values of servicing rights are subject to significant fluctuations as a result of changes in estimated and actual prepayment speeds and default rates and losses. Servicing fee income that is reported on the statement of operations as loan servicing fees is recorded for fees earned for servicing loans. The fees are based on a contractual percentage of the outstanding principal; or a fixed amount per loan and are recorded as income when earned. Late fees and ancillary fees related to loan servicing are not material. First mortgage loans serviced for others are not included in the accompanying consolidated statements of financial condition. The unpaid principal balances of these loans were $90.7 million and $106.4 million at December 31, 2017 and 2016 , respectively. Custodial escrow balances maintained in connection with the foregoing loan servicing activities were $2.6 million and $2.7 million at at December 31, 2017 and 2016 , respectively. Capitalized mortgage servicing rights are included in the other assets in the accompanying consolidated statement of financial condition. Servicing rights were $513,000 and $612,000 at December 31, 2017 and 2016 , respectively, with no valuation allowance at December 31, 2017 and 2016 . Other Real Estate Owned ("OREO") : Foreclosed assets are initially recorded at fair value less cost to sell when acquired, establishing a new cost basis. Physical possession of residential real estate property collateralizing a consumer mortgage loan occurs when the legal title is obtained upon completion of foreclosure or when the borrower conveys all interest in the property to satisfy the loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. These assets are subsequently accounted for at a lower of cost or fair value less estimated cost to sell. If fair value declines subsequent to foreclosure, a valuation allowance is recorded through expense. Operating expenses, gains and losses on disposition, and changes in the valuation allowance are reported in noninterest expense as operations of other real estate owned. Premises and Equipment : Land is carried at cost. Premises and equipment are stated at cost less accumulated depreciation. Depreciation is included in noninterest expense and is computed on the straight-line method over the estimated useful lives of the assets. Useful lives are estimated to be 25 to 40 years for buildings and improvements that extend the life of the original building, ten to 20 years for routine building improvements, five to 15 years for furniture and equipment, two to five years for computer hardware and software and no greater than four years on automobiles. The cost of maintenance and repairs is charged to expense as incurred and significant repairs are capitalized. In December 2017, we agreed to a letter of intent to sell our corporate office building in Burr Ridge, Illinois. In January 2018, we executed a formal sales agreement to sell the property subject to certain contingencies exclusively in the control of the purchaser. The asset is recorded in our financial statements at December 31, 2017 as premises held-for-sale at a net cost of $5.7 million . Other Intangible Assets : Intangible assets acquired in a purchase business combination with definite useful lives are amortized over their estimated useful lives to their estimated residual values. Core deposit intangible assets (“CDI”), are recognized at the time of acquisition based on valuations prepared by independent third parties or other estimates of fair value. In preparing such valuations, variables such as deposit servicing costs, attrition rates, and market discount rates are considered. CDI assets are amortized to expense over their useful lives. Bank Owned Life Insurance: The Company has purchased life insurance policies on certain key executives. The Company owned life insurance is recorded at the amount that can be realized under the insurance contract at the balance sheet date, which is the cash surrender value adjusted for other charges or other amounts due that are probable at settlement. Long-Term Assets : Premises and equipment, core deposit and other intangible assets, and other long-term assets are reviewed for impairment when events indicate that their carrying amount may not be recoverable from future undiscounted cash flows. If impaired, the assets are recorded at fair value. Loan Commitments and Related Financial Instruments : Financial instruments include off-balance-sheet credit instruments, such as commitments to make loans and commercial letters of credit, issued to meet customer financing needs. The face amount for these items represents the exposure to loss, before considering customer collateral or ability to repay. Such financial instruments are recorded when they are funded. Income Taxes : Income tax expense is the total of the current year income tax due or refundable and the change in deferred tax assets and liabilities. Under GAAP, a deferred tax asset valuation allowance is required to be recognized if it is “more likely than not” that the deferred tax asset will not be realized. The determination of the realizability of the deferred tax assets is highly subjective and dependent upon judgment concerning management’s evaluation of both positive and negative evidence, the forecasts of future taxable income, applicable tax planning strategies, and assessments of current and future economic and business conditions. The Company considers both positive and negative evidence regarding the ultimate realizability of our deferred tax assets. Examples of positive evidence may include the existence, if any, of taxes paid in available carry-back years and the likelihood that taxable income will be generated in future periods. Examples of negative evidence may include a cumulative loss in the current year and prior two years and negative general business and economic trends. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period of the enactment date. This analysis is updated quarterly and adjusted as necessary. At December 31, 2017 , the Company had a net deferred tax asset of $12.6 million . A tax position is recognized as a benefit only if it is "more likely than not" that the tax position would be sustained in a tax examination, presuming that a tax examination will occur. The amount recognized is the largest amount of tax benefit that is greater than 50% likely to be realized on examination. For tax positions not meeting the "more likely than not" test, no tax benefit is recorded. Retirement Plans : Employee 401(k) and profit sharing plan expense is the amount of matching contributions and any annual discretionary contribution made at the discretion of the Company’s Board of Directors. Deferred compensation expense allocates the benefits over years of service. Employee Stock Ownership Plan (“ESOP”) : The cost of shares issued to the ESOP, but not yet allocated to participants, was shown as a reduction of stockholders’ equity. Compensation expense is based on the market price of shares as they are committed to be released to participant accounts. Dividends on allocated ESOP shares reduce retained earnings; dividends on unearned ESOP shares reduce debt and accrued interest. Earnings per Common Share : Basic earnings per common share is net income divided by the weighted average number of common shares outstanding during the period. ESOP shares are considered outstanding for this calculation unless unearned. Diluted earnings per common share is net income divided by the weighted average number of common shares outstanding during the period plus the dilutive effect of restricted stock shares and the additional potential shares issuable under stock options. Loss Contingencies : Loss contingencies, including claims and legal actions arising in the ordinary course of business, are recorded as liabilities when the likelihood of loss is probable and an amount or range of loss can be reasonably estimated. Management does not believe that there are such matters that will have a material effect on the financial statements as of December 31, 2017 . Restrictions on Cash : Cash on hand or on deposit with the Federal Reserve Bank that is required to meet regulatory reserve and clearing requirements. Fair Values of Financial Instruments : Fair values of financial instruments are estimated using relevant market value information and other assumptions, as more fully disclosed in a separate note. Fair value estimates involve uncertainties and matters of significant judgment regarding interest rates, credit risk, prepayments, and other factors, especially in the absence of broad markets for particular items. Changes in assumptions or in market conditions could significantly affect the estimates. Comprehensive Income : Comprehensive income consists of net income and other comprehensive income (loss). Other comprehensive income (loss) includes unrealized gains and losses on securities, net of tax, which are also recognized as separate components of stockholders’ equity. Stock-based Compensation: Compensation cost is recognized for stock options and restricted stock awards issued to employees, based on the fair value of these awards at the date of grant. The Black-Scholes model is utilized to estimate the fair value of stock options, while the market price of the Company’s common stock at the date of grant is used for restricted stock awards. Compensation cost is recognized over the required service period, generally defined as the vesting period. Transfers of Financial Assets: Transfers of financial assets are accounted for as sales when control over the assets has been relinquished. Control over transferred assets is deemed to be surrendered when the assets have been isolated from the Company, the transferee obtains the right (free of conditions that constrain it from taking advantage of that right) to pledge or exchange the transferred assets, and the Company does not maintain effective control over the transferred assets through an agreement to repurchase them before their maturity. Operating Segments: While management monitors the revenue streams of the various products and services, operations are managed and financial performance is evaluated on a Company-wide basis. Operating results are not reviewed by senior management to make resource allocation or performance decisions. Accordingly, all of the financial service operations are considered by management to be aggregated in one reportable operating segment. Reclassifications : Certain reclassifications have been made in the prior year’s financial statements to conform to the current year’s presentation. Recent Accounting Pronouncements In May 2014, the FASB issued an update (ASU No. 2014-09, “Revenue from Contracts with Customers”) creating FASB Topic 606, Revenue from Contracts with Customers. The guidance in this update affects any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of nonfinancial assets unless those contracts are within the scope of other standards (for example, insurance contracts or lease contracts). The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The guidance provides steps to follow to achieve the core principle. An entity should disclose sufficient information to enable users of financial statements to understand the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. Qualitative and quantitative information is required about contracts with customers, significant judgments and changes in judgments, and assets recognized from the costs to obtain or fulfill a contract. The amendments in this update become effective for annual periods and interim periods within those annual periods beginning after December 15, 2017. We have evaluated the impact of adopting the update and have concluded that it will not have a significant impact to our consolidated financial statements. The Company’s revenue streams that are in-scope of the update include: financed OREO sales; deposit fees, including ATM fees, overdraft fees, maintenance fees and dormancy fees; credit and debit card fees, and trust fees. For the in-scope revenue streams, our current revenue recognition would not be different than revenue recognition under the update. The Company has infrequently financed an OREO sale. Our customer contracts generally do not have performance obligations and fees are assessed and collected as the transaction occurs. The Company’s fee income is not material for any individual income stream. The consolidated financial statements will be impacted by new disclosures required by the update. In January 2016, the FASB issued an update (ASU No. 2016-01, “Financial Instruments–Recognition and Measurement of Financial Assets and Liabilities”). The new guidance is intended to improve the recognition and measurement of financial instruments by requiring: equity investments (other than equity method or consolidation) to be measured at fair value with changes in fair value recognized in net income; public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; separate presentation of financial assets and financial liabilities by measurement category and form of financial assets ( i.e., securities or loans and receivables) on the balance sheet or the accompanying notes to the financial statements; eliminating the requirement to disclose the fair value of financial instruments measured at amortized cost for organizations that are not public business entities; eliminating the requirement for non-public business entities to disclose the method(s) and significant assumptions used to estimate the fair value that is to be required to be disclosed for financial instruments measured at amortized cost on the balance sheet; and requiring a reporting organization to present separately in other comprehensive income the portion of the total change in fair value of a liability resulting from the change in the instrument-specific credit risk (also referred to as “own credit”) when the organization has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. The new guidance is effective for public business entities for fiscal years beginning after December 15, 2017. We have evaluated the impact of adopting the new guidance on the consolidated financial statements. Our finding is that the new pronouncement will not have a significant impact on our Statement of Operations as we only have one equity security that was valued at $499,000 at December 31, 2017 . In February 2016, the FASB issued ASU No. 2016-02, “Leases (Topic 842)” (“ASU 2016-02”). The standard requires a lessee to recognize assets and liabilities on the balance sheet for leases with lease terms greater than 12 months. ASU 2016-02 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018, and early adoption is permitted. We are currently evaluating the impact that the standard will have on our consolidated financial statements. Our preliminary finding is that the new pronouncement will not have a significant impact on our consolidated fina

Earnings Per Share (Notes)

Earnings Per Share (Notes)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings Per Share	Amounts reported in earnings per share reflect net income available to common stockholders for the period divided by the weighted average number of shares of common stock outstanding during the period, exclusive of unearned ESOP shares and unvested restricted stock shares. Stock options and restricted stock are regarded as potential common stock and are considered in the diluted earnings per share calculations to the extent that they would have a dilutive effect if converted to common stock. For the years ended December 31, 2017 2016 2015 Net income available to common stockholders $ 9,004 $ 7,502 $ 8,675 Average common shares outstanding 18,429,018 19,673,416 20,708,775 Less: Unearned ESOP shares (148,179 ) (682,362 ) (780,227 ) Unvested restricted stock shares (940 ) (3,103 ) (10,545 ) Weighted average common shares outstanding 18,279,899 18,987,951 19,918,003 Add - Net effect of dilutive stock options and unvested restricted stock 437 59,188 3,516 Weighted average dilutive common shares outstanding 18,280,336 19,047,139 19,921,519 Basic earnings per common share $ 0.49 $ 0.40 $ 0.44 Diluted earnings per common share $ 0.49 $ 0.39 $ 0.44 Number of antidilutive stock options excluded from the diluted earnings per share calculation — 536,459 536,459 Weighted average exercise price of anti-dilutive option shares $ — $ 12.99 $ 12.99

Securities (Notes)

Securities (Notes)	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Securities	The fair value of securities and the related gross unrealized gains and losses recognized in accumulated other comprehensive income is as follows: Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value December 31, 2017 Certificates of deposit $ 75,916 $ — $ — $ 75,916 Equity mutual fund 500 — (1 ) 499 Mortgage-backed securities - residential 11,969 520 (17 ) 12,472 Collateralized mortgage obligations - residential 4,481 16 (11 ) 4,486 SBA-guaranteed loan participation certificates 10 — — 10 $ 92,876 $ 536 $ (29 ) $ 93,383 December 31, 2016 Certificates of deposit $ 85,938 $ — $ — $ 85,938 Equity mutual fund 500 — (1 ) 499 Mortgage-backed securities - residential 14,561 644 (21 ) 15,184 Collateralized mortgage obligations - residential 5,587 15 (28 ) 5,574 SBA-guaranteed loan participation certificates 17 — — 17 $ 106,603 $ 659 $ (50 ) $ 107,212 Mortgage-backed securities and collateralized mortgage obligations reflected in the preceding table were issued by U.S. government-sponsored entities and agencies, Freddie Mac, Fannie Mae and Ginnie Mae, and are obligations which the government has affirmed its commitment to support. All securities reflected in the preceding table were classified as available-for-sale at December 31, 2017 and 2016 . The amortized cost and fair values of securities at December 31, 2017 by contractual maturity are shown below. Securities not due at a single maturity date are shown separately. Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. December 31, 2017 Amortized Cost Fair Value Due in one year or less $ 75,916 $ 75,916 Mortgage-backed securities - residential 11,969 12,472 Collateralized mortgage obligations - residential 4,481 4,486 SBA-guaranteed loan participation certificates 10 10 $ 92,376 $ 92,884 Investment securities available for sale with carrying amounts of $3.7 million and $4.7 million at December 31, 2017 and 2016 , respectively, were pledged as collateral on customer repurchase agreements and for other purposes as required or permitted by law. Sales of securities were as follows: For the years ended December 31, 2017 2016 2015 Proceeds $ — $ 46 $ — Gross gains — 46 — Gross losses — — — Securities with unrealized losses at December 31, 2017 and 2016 not recognized in income are as follows: Less than 12 Months 12 Months or More Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss December 31, 2017 Equity mutual fund $ 499 $ (1 ) $ — $ — $ 499 $ (1 ) Mortgage-backed securities - residential — — 1,149 (17 ) 1,149 (17 ) Collateralized mortgage obligations - residential — — 2,083 (11 ) 2,083 (11 ) $ 499 $ (1 ) $ 3,232 $ (28 ) $ 3,731 $ (29 ) December 31, 2016 Equity mutual fund $ 499 $ (1 ) $ — $ — $ 499 $ (1 ) Mortgage-backed securities - residential 1,187 (21 ) — — 1,187 (21 ) Collateralized mortgage obligations - residential 3,691 (18 ) 1,028 (10 ) 4,719 (28 ) $ 5,377 $ (40 ) $ 1,028 $ (10 ) $ 6,405 $ (50 ) The Company evaluates marketable investment securities with significant declines in fair value on a quarterly basis to determine whether they should be considered other-than-temporarily impaired under current accounting guidance, which generally provides that if a marketable security is in an unrealized loss position, whether due to general market conditions or industry or issuer-specific factors, the holder of the securities must assess whether the impairment is other-than-temporary. An equity mutual fund and certain residential mortgage-backed securities and collateralized mortgage obligations that the Company holds in its investment portfolio were in an unrealized loss position at December 31, 2017 , but the unrealized loss was not considered significant under the Company’s impairment testing methodology. In addition, the Company does not intend to sell these securities, and it is not likely that the Company will be required to sell the securities before their anticipated recovery occurs.

Loans Receivable (Notes)

Loans Receivable (Notes)	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Loans Receivable	Loans receivable are as follows: December 31, 2017 2016 One-to-four family residential real estate $ 97,814 $ 135,218 Multi-family mortgage 588,383 542,887 Nonresidential real estate 169,971 182,152 Construction and land 1,358 1,302 Commercial loans 152,552 99,088 Commercial leases 310,076 356,514 Consumer 1,597 2,255 1,321,751 1,319,416 Net deferred loan origination costs 1,266 1,663 Allowance for loan losses (8,366 ) (8,127 ) Loans, net $ 1,314,651 $ 1,312,952 Loan Origination/Risk Management. The Company has certain lending policies and procedures in place that are designed to maximize loan income within an acceptable level of risk. The Company reviews and approves these policies and procedures on a periodic basis. A reporting system supplements the review process by providing management with frequent reports related to loan production, loan quality, concentrations of credit, loan delinquencies and nonperforming and potential problem loans via trend and risk rating migration. The Company requires title insurance insuring the priority of our lien on real estate collateral, fire and extended coverage casualty insurance, and, if appropriate, flood insurance, in order to protect our security interest in the underlying real property. The majority of the loans the Company originates are commercial-related loans, such as multi-family, nonresidential real estate, commercial, construction and land loans, and commercial leases. In addition, we originated one-to-four family residential mortgage loans and consumer loans until December 31, 2017. We also occasionally purchase and sell loan participations. The following briefly describes our principal loan products. The Company originates real estate loans principally secured by first liens both non-owner occupied and owner occupied commercial real estate. The non-owner occupied commercial real estate properties are predominantly multi-family apartment buildings, office buildings, light industrial buildings, shopping centers and mixed-use developments and, to a much lesser extent, more specialized properties such as nursing homes and other healthcare facilities. Multi-family mortgage loans generally are secured by multi-family rental properties such as apartment buildings, including subsidized apartment units. In general, loan amounts range between $500,000 and $5.0 million . Approximately 46.5% of the collateral is located outside of our primary market area; however, we do not have a concentration in any single market in excess of 25% of our loan portfolio outside of our primary market area. In underwriting multi-family mortgage loans, the Company considers a number of factors, which include the projected net cash flow to the loan’s debt service requirement (generally requiring a minimum ratio of 120% ), the age and condition of the collateral, the financial resources and income level of the borrower, the borrower’s experience in owning or managing similar properties and, proximity to diverse employment opportunities. Multi-family mortgage loans are generally originated in amounts up to 80% of the appraised value of the property securing the loan. Personal guarantees are usually obtained on multi-family mortgage loans if the borrower/property owner is a legal entity. Loans secured by multi-family mortgages generally involve a greater degree of credit risk than one-to-four family residential mortgage loans and carry larger loan balances. This increased credit risk is a result of several factors, including the concentration of principal in a limited number of loans and borrowers, the effects of general economic conditions on income producing properties, and the increased difficulty of evaluating and monitoring these types of loans. Furthermore, the repayment of loans secured by multi-family mortgages typically depends upon the successful operation of the related real estate property. If the cash flow from the project is reduced below acceptable thresholds, the borrower’s ability to repay the loan may be impaired. The Company emphasizes nonresidential real estate loans with initial principal balances between $250,000 and $5.0 million . Substantially all of our nonresidential real estate loans are secured by properties located in our primary market area. The Company’s nonresidential real estate loans are generally written as three - or five -year adjustable-rate mortgages or mortgages with balloon maturities of three or five years. Amortization on these loans is typically based on 20 - to 30 -year schedules. The Company also originates some 15 -year fixed-rate, fully amortizing loans. In the underwriting of nonresidential real estate loans, the Company generally lends up to 80% of the property’s appraised value. Decisions to lend are based on the economic viability of the property as the primary source of repayment and the creditworthiness of the borrower. In evaluating a proposed commercial real estate loan, we emphasize the ratio of the property’s projected net cash flow to the loan’s debt service requirement (generally requiring a minimum ratio of 120% ), computed after deduction for a vacancy factor and property expenses we deem appropriate. Personal guarantees are usually pursued and obtained from nonresidential real estate borrowers. Nonresidential real estate loans generally carry higher interest rates and have shorter terms than one-to-four family residential mortgage loans. Nonresidential real estate loans, however, entail significant additional credit risks compared to one-to-four family residential mortgage loans, as they typically involve larger loan balances concentrated with single borrowers or groups of related borrowers. In addition, the payment of loans secured by income-producing properties typically depends on the successful operation of the related real estate project and thus may be subject to a greater extent to adverse conditions in the real estate market and in the general economy. The Company makes various types of secured and unsecured commercial loans to customers in our market area for the purpose of financing equipment acquisition, expansion, working capital and other general business purposes. The terms of these loans generally range from less than one year to five years. The loans are either negotiated on a fixed-rate basis or carry adjustable interest rates indexed to (i) a lending rate that is determined internally, or (ii) a short-term market rate index. Commercial credit decisions are based upon our assessment of the borrower’s cash flow, proposed collateral, business and credit history and any additional positive or negative credit risk factors.. The Company determines the borrower’s ability to repay in accordance with the proposed terms of the loans and we assess the risks involved. An evaluation is made of the borrower to determine character and capacity to manage. Personal guarantees of the principals are pursued and usually obtained. In addition to evaluating the loan borrower’s financial statements, we consider the adequacy of the primary and secondary sources of repayment for the loan. Independent reports of the borrower’s credit history supplement our analysis of the borrower’s creditworthiness and at times are supplemented with inquiries to other banks and trade investigations. Moreover, certain assets listed on personal financial statements are verified. Proposed collateral for a secured transaction also is analyzed to determine its marketability. Commercial business loans generally have higher interest rates than residential loans of like duration because they have a higher risk of default since their repayment generally depends on the successful operation of the borrower’s business and the sufficiency of any collateral. Pricing of commercial loans is based primarily on the credit risk of the borrower, with due consideration given to borrowers with appropriate deposit relationships. The Company also lends money to small and mid-size leasing companies for equipment financing leases. Generally, commercial leases are secured by an assignment by the leasing company of the lease payments and by a secured interest in the equipment being leased. In most cases, the lessee acknowledges our security interest in the leased equipment and agrees to send lease payments directly to us. Consequently, the Company underwrites lease loans by examining the creditworthiness of the lessee rather than the lessor. Lease loans generally are non-recourse to the leasing company. The Company’s commercial leases are secured primarily by technology equipment, medical equipment, material handling equipment and other capital equipment. Lessees tend to be publicly-traded companies with investment-grade rated debt or companies that have not issued public debt and therefore do not have a public debt rating. The Company requires that a minimum of 50% of our commercial lessees have an investment-grade public debt rating by Moody’s or Standard & Poors, or the equivalent. Commercial leases to these entities have a maximum outstanding credit exposure of $15.0 million to any single entity. If the lessee does not have a public debt rating, they are subject to the same internal credit analysis as any other customer. Typically, commercial leases to these lessees have a maximum maturity of five years and a maximum outstanding credit exposure of $10.0 million to any single entity. In addition, the Company will originate commercial leases to lessees with below investment-grade public debt ratings and have a maximum outstanding credit exposure of $10.0 million to any single entity. Lease loans are almost always fully amortizing, with fixed interest rates. Although the Company does not actively originate construction and land loans presently, construction and land loans generally consist of land acquisition loans to help finance the purchase of land intended for further development, including single-family homes, multi-family housing and commercial income property, development loans to builders in our market area to finance improvements to real estate, consisting mostly of single-family subdivisions, typically to finance the cost of utilities, roads, sewers and other development costs. These builders generally rely on the sale of single-family homes to repay development loans, although in some cases the improved building lots may be sold to another builder, often in conjunction with development loans. Construction and land loans typically involve a higher degree of credit risk than financing on improved, owner occupied real estate. The risk of loss on construction and land loans is largely dependent upon the accuracy of the initial appraisal of the property’s value upon completion of construction or development; the estimated cost of construction, including interest; and the estimated time to complete and/or sell or lease such property. In the event that the Company were to make any new construction and development loans, it would seek to minimize these risks by maintaining consistent lending policies and underwriting standards. However, if the estimate of value proves to be inaccurate, the cost of completion is greater than expected, the length of time to complete and/or sell or lease the collateral property is greater than anticipated, or if there is a downturn in the local economy or real estate market, the property could have a value upon completion that is insufficient to assure full repayment of the loan. This could have a material adverse effect on the quality of the construction and land loan portfolio, and could result in significant losses or delinquencies if that portfolio were ever to increase in size. Up through December 31, 2017, the Company offered conforming and non-conforming, fixed-rate and adjustable-rate residential mortgage loans with maturities of up to 30 years and maximum loan amounts generally of up to $2.5 million . One-to-four family residential mortgage loans were generally underwritten according to Fannie Mae guidelines, and loans that conformed to such guidelines are referred to as “conforming loans.” The Company generally originated both fixed- and adjustable-rate loans in amounts up to the maximum conforming loan limits as established by Fannie Mae, which is currently $424,100 for single-family homes. Private mortgage insurance is required for first mortgage loans with loan-to-value ratios in excess of 80% . The Company also occasionally originated loans above conforming limits, sometimes referred to as “jumbo loans,” that were underwritten to the credit standards of Fannie Mae. These loans were generally eligible for sale to various firms that specialize in the purchase of such non-conforming loans. The ability of the Company’s borrowers to repay their loans, and the value of the collateral securing such loans, could be adversely impacted by economic weakness in its local markets as a result of unemployment, declining real estate values, or increased residential, office, industrial and retail shopping vacancies due to changes in business conditions. This not only could result in the Company experiencing charge-offs and/or nonperforming assets, but also could necessitate an increase in the provision for loan losses. These events, if they were to recur, would have an adverse impact on the Company’s results of operations and its capital. The following tables present the balance in the allowance for loan losses and the loans receivable by portfolio segment and based on impairment method: Allowance for loan losses Loan Balances Individually evaluated for impairment Collectively evaluated for impairment Total Individually evaluated for impairment Collectively evaluated for impairment Total December 31, 2017 One-to-four family residential real estate $ — $ 850 $ 850 $ 4,265 $ 93,549 $ 97,814 Multi-family mortgage — 3,849 3,849 949 587,434 588,383 Nonresidential real estate — 1,605 1,605 — 169,971 169,971 Construction and land — 32 32 — 1,358 1,358 Commercial loans — 1,357 1,357 — 152,552 152,552 Commercial leases — 655 655 — 310,076 310,076 Consumer — 18 18 — 1,597 1,597 $ — $ 8,366 $ 8,366 $ 5,214 $ 1,316,537 1,321,751 Net deferred loan origination costs 1,266 Allowance for loan losses (8,366 ) Loans, net $ 1,314,651 Allowance for loan losses Loan Balances Individually evaluated for impairment Collectively evaluated for impairment Total Individually evaluated for impairment Collectively evaluated for impairment Total December 31, 2016 One-to-four family residential real estate $ — $ 1,168 $ 1,168 $ 4,962 $ 130,256 $ 135,218 Multi-family mortgage — 3,647 3,647 787 542,100 542,887 Nonresidential real estate 26 1,768 1,794 260 181,892 182,152 Construction and land — 32 32 — 1,302 1,302 Commercial loans — 733 733 — 99,088 99,088 Commercial leases — 714 714 — 356,514 356,514 Consumer — 39 39 — 2,255 2,255 $ 26 $ 8,101 $ 8,127 $ 6,009 $ 1,313,407 1,319,416 Net deferred loan origination costs 1,663 Allowance for loan losses (8,127 ) Loans, net $ 1,312,952 Activity in the allowance for loan losses is as follows: For the years ended December 31, 2017 2016 2015 Beginning balance $ 8,127 $ 9,691 $ 11,990 Loans charged off: One-to-four family residential real estate (318 ) (539 ) (386 ) Multi-family mortgage (10 ) (79 ) (198 ) Nonresidential real estate (165 ) (1,718 ) (391 ) Commercial loans — — (152 ) Consumer (10 ) (25 ) (16 ) (503 ) (2,361 ) (1,143 ) Recoveries: One-to-four family residential real estate 145 321 702 Multi-family mortgage 70 162 182 Nonresidential real estate 17 200 509 Construction and land — 35 44 Commercial loans 594 309 611 Commercial leases 2 7 1 Consumer 1 2 1 829 1,036 2,050 Net recoveries (charge-off) 326 (1,325 ) 907 Recovery of loan losses (87 ) (239 ) (3,206 ) Ending balance $ 8,366 $ 8,127 $ 9,691 Impaired loans Several of the following disclosures are presented by “recorded investment,” which the FASB defines as “the amount of the investment in a loan, which is not net of a valuation allowance, but which does reflect any direct write-down of the investment.” The following represents the components of recorded investment: Loan principal balance Less unapplied payments Plus negative unapplied balance Less escrow balance Plus negative escrow balance Plus unamortized net deferred loan costs Less unamortized net deferred loan fees Plus unamortized premium Less unamortized discount Less previous charge-offs Plus recorded accrued interest Less reserve for uncollected interest = Recorded investment The following tables present loans individually evaluated for impairment by class of loans: Loan Balance Recorded Investment Partial Charge-off Allowance for Loan Losses Allocated Average Investment in Impaired Loans Interest Income Recognized December 31, 2017 With no related allowance recorded One-to-four family residential real estate $ 5,049 $ 4,248 $ 806 $ — $ 4,212 $ 197 Multi-family mortgage 958 948 — — 847 41 $ 6,007 $ 5,196 $ 806 $ — $ 5,059 $ 238 Loan Balance Recorded Investment Partial Charge-off Allowance for Loan Losses Allocated Average Investment in Impaired Loans Interest Income Recognized December 31, 2016 With no related allowance recorded One-to-four family residential real estate $ 5,379 $ 4,548 $ 886 $ — $ 2,947 $ 70 One-to-four family residential real estate - non-owner occupied 503 386 119 — 251 9 Multi-family mortgage 787 787 — — 980 41 6,669 5,721 1,005 — 4,178 120 With an allowance recorded - Nonresidential real estate 262 260 21 26 164 — $ 6,931 $ 5,981 $ 1,026 $ 26 $ 4,342 $ 120 Nonaccrual loans The following tables present the recorded investment in nonaccrual and loans past due over 90 days still on accrual by class of loans: Loan Balance Recorded Investment Loans Past Due Over 90 Days, still accruing December 31, 2017 One-to-four family residential real estate $ 3,413 $ 1,918 $ — One-to-four family residential real estate – non owner occupied 308 109 — Multi-family mortgage 376 363 — Nonresidential real estate — — — $ 4,097 $ 2,390 $ — December 31, 2016 One-to-four family residential real estate $ 2,861 $ 2,483 $ — One-to-four family residential real estate – non owner occupied 428 368 — Multi-family mortgage 187 185 — Nonresidential real estate 262 260 — $ 3,738 $ 3,296 $ — Nonaccrual loans and impaired loans are defined differently. Some loans may be included in both categories, and some may only be included in one category. Nonaccrual loans include both smaller balance homogeneous loans that are collectively evaluated for impairment and individually classified impaired loans. The Company’s reserve for uncollected loan interest was $103,000 and $199,000 at December 31, 2017 and 2016 , respectively. When a loan is on non-accrual status and the ultimate collectability of the total principal of an impaired loan is in doubt, all payments are applied to principal under the cost recovery method. Alternatively, when a loan is on non-accrual status but there is doubt concerning only the ultimate collectability of interest, contractual interest is credited to interest income only when received, under the cash basis method pursuant to the provisions of FASB ASC 310–10, as applicable. In all cases, the average balances are calculated based on the month–end balances of the financing receivables within the period reported pursuant to the provisions of FASB ASC 310–10, as applicable. Past Due Loans The following tables present the aging of the recorded investment in past due loans at December 31, 2017 by class of loans: 30-59 Days Past Due 60-89 Days Past Due Greater Than 89 Days Past Due Total Past Due Loans Not Past Due Total One-to-four family residential real estate $ 86 $ 99 $ 1,801 $ 1,986 $ 74,216 $ 76,202 One-to-four family residential real estate - non-owner occupied 10 3 86 99 20,944 21,043 Multi-family mortgage - Illinois 172 — 364 536 287,171 287,707 Multi-family mortgage - Other — — — — 296,440 296,440 Nonresidential real estate 608 — — 608 166,071 166,679 Construction — — — — 1,103 1,103 Land — — — — 259 259 Commercial loans: Regional Commercial Banking — — — — 40,935 40,935 Health Care — — — — 71,738 71,738 Direct Commercial Lessor — — — — 40,237 40,237 Commercial leases: — Investment-grade 934 — — 934 207,747 208,681 Other 288 — — 288 102,873 103,161 Consumer — — — — 1,605 1,605 Total $ 2,098 $ 102 $ 2,251 $ 4,451 $ 1,311,339 $ 1,315,790 The following tables present the aging of the recorded investment in past due loans as December 31, 2016 by class of loans: 30-59 Days Past Due 60-89 Days Past Due Greater Than 89 Days Past Due Total Past Due Loans Not Past Due Total One-to-four family residential real estate $ 984 $ 335 $ 2,235 $ 3,554 $ 92,665 $ 96,219 One-to-four family residential real estate - non-owner occupied 664 114 368 1,146 37,179 38,325 Multi-family mortgage - Illinois 605 439 184 1,228 294,223 295,451 Multi-family mortgage - Other — — — — 243,944 243,944 Nonresidential real estate — — 260 260 178,644 178,904 Construction — — — — 950 950 Land — — — — 349 349 Commercial loans: Regional Commercial Banking — — — — 26,480 26,480 Health Care — — — — 41,086 41,086 Direct Commercial Lessor — — — — 31,847 31,847 Commercial leases: — Investment-grade 51 — — 51 273,405 273,456 Other — — — — 84,988 84,988 Consumer — — — — 2,263 2,263 $ 2,304 $ 888 $ 3,047 $ 6,239 $ 1,308,023 $ 1,314,262 Troubled Debt Restructurings The Company evaluates loan extensions or modifications in accordance with FASB ASC 310–40 with respect to the classification of the loan as a TDR. In general, if the Company grants a loan extension or modification to a borrower for other than an insignificant period of time that includes a below–market interest rate, principal forgiveness, payment forbearance or other concession intended to minimize the economic loss to the Company, the loan extension or loan modification is classified as a TDR. In cases where borrowers are granted new terms that provide for a reduction of either interest or principal then due and payable, management measures any impairment on the restructured loan in the same manner as for impaired loans as noted above. The Company had $17,000 of TDRs at December 31, 2017 , compared to $341,000 at December 31, 2016 , with no specific valuation reserves allocated at December 31, 2017 and 2016 . The Company had no outstanding commitments to borrowers whose loans are classified as TDRs at either date. The following table presents loans classified as TDRs: December 31, 2017 2016 One-to-four family residential real estate - Accrual $ — $ 205 One-to-four family residential real estate - Nonaccrual 17 136 $ 17 $ 341 During the year ending December 31, 2017 , there were no loans modified and classified as TDRs. During the year ending December 31, 2016 , the terms of certain loans were modified and classified as TDRs. The modification of the terms of such loans included one or a combination of the following: a reduction of the stated interest rate of the loan; an extension of the maturity date at a stated rate of interest lower than the current market rate for new debt with similar risk; or a permanent reduction of the recorded investment in the loan. The following tables present TDRs that occurred during the year: For the years ended December 31, 2017 2016 Number of loans Pre- Modification outstanding recorded investment Post- Modification outstanding recorded investment Number of loans Pre- Modification outstanding recorded investment Post- Modification outstanding recorded investment One-to-four family residential real estate — $ — $ — 1 $ 63 $ 63 Due to reduction in interest rate Due to extension of maturity date Due to permanent reduction in recorded investment Total For the year ended December 31, 2016 One-to-four family residential real estate $ — $ 63 $ — $ 63 The TDRs described above had no impact on interest income, resulted in no change to the allowance for loan losses and resulted in no charge-offs for the year ended December 31, 2016 . The following table presents TDRs for which there was a payment default within twelve months following the modification: For the years ended December 31, 2017 2016 Number of loans Recorded investment Number of loans Recorded investment One-to-four family residential real estate — $ — 2 $ 87 A loan is considered to be in payment default once it is 90 days contractually past due under the modified terms. The TDRs that subsequently defaulted described above had no material impact on the allowance for loans losses during the year ending December 31, 2016 . The terms of certain other loans were modified during the year ending December 31, 2017 in circumstances that did not meet the definition of a TDR. These loans have a total recorded investment of $149,000 and $868,000 at December 31, 2017 and 2016 , respectively. The modification of these loans involved either a modification of the terms of a loan to borrowers who were not experiencing financial difficulties or a delay in a payment that was considered to be insignificant. In order to determine whether a borrower is experiencing financial difficulty, an evaluation is performed of the probability that the borrower will be in payment default on any of its debt in the foreseeable future without the modification. This evaluation is performed under the Company’s internal underwriting policy. Credit Quality Indicators: The Company categorizes loans into risk categories based on relevant information about the ability of borrowers to service their debt, including current financial information, historical payment experience, credit documentation, public information, and current economic trends, among other factors. The Company analyzes loans individually by classifying the loans based on credit risk. This analysis includes non-homogeneous loans, such as commercial and commercial real estate loans. This analysis is performed on a monthly basis. The Company uses the following definitions for risk ratings: Special Mention. A Special Mention asset has potential weaknesses that deserve management’s close attention. If left uncorrected, these potential weaknesses may result in deterioration of the repayment prospects for the asset or in the institution’s credit position at some future date. Special Mention assets are not adversely classified and do not expose an institution to sufficient risk to warrant adverse classification. Substandard. Loans categorized as substandard continue to accrue interest, but exhibit a well-defined weakness or weaknesses that may jeopardize the liquidation of the debt. The loans continue to accrue interest because they are well secured and collection of principal and interest is expected within a reasonable time. The risk rating guidance published by the Office of the Comptroller of the Currency clarifies that a loan with a well-defined weakness does not have to present a probability of default for the loan to be rated Substandard, and that an individual loan’s loss potential does not have to be distinct for the loan to be rated Substandard. Nonaccrual. An asset classified Nonaccrual has all the weaknesses inherent in one classified substandard with the added characteristic that the weaknesses make collection or liquidation in full, on the basis of currently existing facts, conditions, and values, highly questionable and improbable. The loans were placed on nonaccrual status. Loans not meeting the criteria above that are analyzed individually as part of the above described process are considered “Pass” rated loans. As of December 31, 2017 , and based on the most recent analysis performed, the risk category of loans by class of loans is as follows: Pass Special Mention Substandard Nonaccrual Total One-to-four family residential real estate $ 74,437 $ — $ 255 $ 1,914 $ 76,606 One-to-four family residential real estate - non-owner occupied 21,059 — 40 109 21,208 Multi-family mortgage - Illinois 290,765 — 225 368 291,358 Multi-family mortgage - Other 297,025 — — — 297,025 Nonresidential real estate 169,817 — 154 — 169,971 Construction 1,099 — — — 1,099 Land 259 — — — 259 Commercial loans: Regional commercial banking 36,373 4,528 — — 40,901 Health care 69,480 — 2,248 — 71,728 Direct commercial lessor 39,923 — — — 39,923 Commercial leases: Investment-grade 207,460 — — — 207,460 Other 102,616 — — — 102,616 Consumer 1,597 — — — 1,597 $ 1,311,910 $ 4,528 $ 2,922 $ 2,391 $ 1,321,751 As of December 31, 2016 , and based on the most recent analysis performed, the risk category of loans by class of loans is as follows: Pass Special Mention Substandard Nonaccrual Total One-to-four family residential real estate $ 93,514 $ — $ 629 $ 2,486 $ 96,629 One-to-four family residential real estate - non-owner occupied 38,179 — 41 369 38,589 Multi-family mortgage - Illinois 297,826 122 1,048 187 299,183 Multi-family mortgage - Other 243,704 — — — 243,704 Nonresidential real estate 180,047 — 1,845 260 182,152 Construction 946 — — — 946 Land 356 — — — 356 Commercial loans: Regional commercial banking 26,365 — 66 — 26,431 Health care 41,001 — — — 41,001 Direct commercial lessor 30,881 800 — — 31,681 Commercial leases: Investment-grade 271,972 — — — 271,972 Other 84,356 161 — — 84,517 Consumer 2,255 — — — 2,255 $ 1,311,402 $ 1,083 $ 3,629 $ 3,302 $ 1,319,416

Other Real Estate (Notes)

Other Real Estate (Notes)	12 Months Ended
	Dec. 31, 2017
Other Real Estate Owned [Abstract]
Other Real Estate Owned	Real estate that is acquired through foreclosure or a deed in lieu of foreclosure is classified as OREO until it is sold. When real estate is acquired through foreclosure or by deed in lieu of foreclosure, it is recorded at its fair value, less the estimated costs of disposal. If the fair value of the property is less than the loan balance, the difference is charged against the allowance for loan losses. The following represents the roll forward of OREO and the composition of OREO properties. At and For the Years Ended December 31, 2017 2016 Beginning balance $ 3,895 $ 7,011 New foreclosed properties 2,766 1,251 Valuation adjustments (333 ) (314 ) Sales (3,977 ) (4,053 ) Ending balance $ 2,351 $ 3,895 December 31, 2017 December 31, 2016 Balance Valuation Allowance Net OREO Balance Balance Valuation Allowance Net OREO Balance One–to–four family residential $ 836 $ (9 ) $ 827 $ 1,702 $ (137 ) $ 1,565 Multi-family mortgage — — — 370 — 370 Nonresidential real estate 1,772 (252 ) 1,520 1,171 (105 ) 1,066 Land 48 (44 ) 4 1,101 (207 ) 894 $ 2,656 $ (305 ) $ 2,351 $ 4,344 $ (449 ) $ 3,895 Activity in the valuation allowance is as follows: At and For the Years Ended December 31, 2017 2016 Beginning of year $ 449 $ 1,042 Additions charged to expense 333 314 Reductions from sales of other real estate owned (477 ) (907 ) End of year $ 305 $ 449 At December 31, 2017 , the balance of OREO includes $352,000 foreclosed residential real estate properties recorded as a result of obtaining physical possession of the property without title. At December 31, 2016 the balance of OREO included no foreclosed residential real estate properties recorded as a result of obtaining physical possession of the property without title. At December 31, 2017 and 2016 , the recorded investment of consumer mortgage loans secured by residential real estate properties for which formal foreclosure proceeds are in process was $926,000 and $1.6 million , respectively.

Premises and Equipment (Notes)

Premises and Equipment (Notes)	12 Months Ended
	Dec. 31, 2017
Property, Plant, Equipment And Leases [Abstract]
Premises and Equipment	Year-end premises and equipment are as follows: December 31, 2017 2016 Land and land improvements $ 12,265 $ 13,820 Buildings and improvements 29,556 37,416 Furniture and equipment 9,678 9,660 Computer equipment 3,983 4,058 55,482 64,954 Accumulated depreciation (30,626 ) (33,541 ) $ 24,856 $ 31,413 Depreciation of premises and equipment was $2.0 million , $2.0 million and $2.1 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. In December 2017, we agreed to a letter of intent to sell our corporate office building in Burr Ridge, Illinois. In January 2018, we executed a formal sales agreement to sell the property subject to certain contingencies exclusively in the control of the purchaser. We believe that the transaction will not result in either a significant gain or loss on sale if consummated. The asset is recorded in our financial statements at December 31, 2017 as premises held-for-sale at a net cost of $5.7 million . The Company leases certain branch facilities under non-cancelable operating lease agreements expiring in various years through 2032. Rent expense, net of sublease income, for facilities was $477,000 , $399,000 , and $393,000 in 2017 , 2016 , and 2015 , respectively, excluding taxes, insurance, and maintenance. The projected minimum rental expense under existing leases, not including taxes, insurance, and maintenance, as of December 31, 2017 is as follows: 2018 $ 497 2019 471 2020 459 2021 464 2022 491 Thereafter 3,753 $ 6,135 The Company has subleased some of its branch facilities and currently is entitled to receive income as follows: 2018 $ 2 2019 2 2020 2 2021 1 2022 1 $ 8

Core Deposit Intangible (Notes)

Core Deposit Intangible (Notes)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Core Deposit Intangible	The following table presents the changes in the carrying amount of core deposit intangible, gross carrying amount, accumulated amortization, and net book value: December 31, 2017 2016 Balance at the beginning of the year $ 782 $ 1,305 Amortization (496 ) (523 ) Additions — — Net Carrying Value $ 286 $ 782 Gross carrying amount $ 5,932 $ 5,932 Accumulated amortization (5,646 ) (5,150 ) Net Carrying Value $ 286 $ 782 Aggregate amortization expense was $496,000 , $523,000 and $550,000 for 2017 , 2016 and 2015 , respectively. Estimated amortization expense for each of the next five years is as follows: 2018 $ 184 2019 61 2020 34 2021 7 2022 —

Deposits (Notes)

Deposits (Notes)	12 Months Ended
	Dec. 31, 2017
Deposits [Abstract]
Deposits	Composition of deposits is as follows: December 31, 2017 2016 Noninterest-bearing demand deposits $ 234,354 $ 249,539 Interest-bearing NOW accounts 289,657 267,054 Money market accounts 299,581 311,183 Savings deposits 160,501 160,002 Certificates of deposit 355,958 351,612 $ 1,340,051 $ 1,339,390 Time deposits that meet or exceed the FDIC Insurance limit of $250,000 were $50.3 million and $18.7 million at December 31, 2017 and 2016 , respectively. Scheduled maturities of certificates of deposit for the next five years are as follows: 2018 $ 258,567 2019 68,756 2020 16,421 2021 8,697 2022 3,517

Borrowings (Notes)

Borrowings (Notes)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Borrowings	ear-end, advances from the FHLB were as follows: December 31, 2017 2016 Contractual Rate Amount Contractual Rate Amount Fixed-rate advance from FHLB, due within 1 year 1.34 % $ 60,000 0.67 % $ 50,000 The Company maintains a collateral pledge agreement covering secured advances whereby the Company has agreed to keep on hand, free of all other pledges, liens, and encumbrances, specifically identified whole first mortgages on improved residential property not more than 90-days delinquent to secure advances from the FHLB. All of the Bank’s FHLB common stock is pledged as additional collateral for these advances. At December 31, 2017 , $63.7 million and $376.5 million of first mortgage and multi-family mortgage loans, respectively, collateralized potential advances. At December 31, 2017 , we had the ability to borrow an additional $322.2 million under our credit facilities with the FHLB. The Company also had available pre-approved overnight federal funds borrowing. At December 31, 2017 and 2016 , there was no outstanding balance on these lines.

Income Taxes (Notes)

Income Taxes (Notes)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	The income tax expense is as follows: For the years ended December 31, 2017 2016 2015 Current expense (benefit) $ (2,658 ) $ 308 $ 346 Deferred expense 7,361 4,390 5,079 Expense due to enactment of federal tax reform 2,487 — — Total income tax expense $ 7,190 $ 4,698 $ 5,425 A reconciliation of the provision for income taxes computed at the statutory federal corporate tax rate of 34% for 2017 , 2016 and 2015 to the income tax expense in the consolidated statements of operations follows: For the years ended December 31, 2017 2016 2015 Expense computed at the statutory federal tax rate $ 5,506 $ 4,148 $ 4,794 State taxes and other, net (204 ) 464 626 Bank owned life insurance (90 ) (70 ) (66 ) ESOP/Share based compensation (509 ) 156 71 Expense due to enactment of federal tax reform 2,487 — — $ 7,190 $ 4,698 $ 5,425 Effective income tax rate 44.77 % 38.51 % 38.48 % Retained earnings at December 31, 2017 and 2016 include $14.9 million for which no deferred federal income tax liability has been recorded. This amount represents an allocation of income to bad debt deductions for tax purposes alone. The net deferred tax asset is as follows: December 31, 2017 2016 Gross Deferred tax assets Allowance for loan losses $ 2,258 $ 3,117 Alternative minimum tax, general business credit and net operating loss carryforwards 11,864 20,857 Tax deductible goodwill and core deposit intangible 801 1,466 Other 1,395 2,540 16,318 27,980 Gross Deferred tax liabilities Net deferred loan origination costs (1,255 ) (1,874 ) Purchase accounting adjustments (1,744 ) (2,644 ) Other (619 ) (817 ) Unrealized gain on securities (137 ) (234 ) (3,755 ) (5,569 ) $ 12,563 $ 22,411 As of December 31, 2017 and 2016 , the Company’s net deferred tax asset (“DTA”) was $12.6 million and $22.4 million , respectively. On December 22, 2017, H.R. 1, commonly known as the Tax Cuts and Job Act (the "Act"), was signed into law. Among other things, the Act reduces our corporate federal tax rate from 34% to 21% effective January 1, 2018. As a result, we were required to re-measure, through income tax expense our deferred tax assets and liabilities using the enacted rate at which we expect them to be recovered or settled. The re-measurement of our net deferred tax asset resulted in additional tax expense of $2.5 million . A DTA valuation allowance is required under ASC 740 when the realization of a DTA is assessed and the assessment indicates that it is “more likely than not” ( i.e., more than 50% likely) that all or a portion of the DTA will not be realized. All available evidence, both positive and negative must be considered to determine whether, based on the weight of that evidence, a valuation allowance against the net DTA is required. Objectively verifiable evidence is assigned greater weight than evidence that is not objectively verifiable. The valuation allowance is analyzed quarterly for changes affecting the DTA. The Company’s ability to realize the DTA is dependent upon the generation of future taxable income during the periods in which the tax attributes underlying the DTA become deductible. The amount of the DTA that will ultimately be realized will be impacted by the Company’s future taxable income, any changes to the many variables that could impact future taxable income and the then applicable corporate tax rate. As of December 31, 2017 and 2016 , management determined that it is more likely than not that the Company will be able to utilize the entire DTA. At December 31, 2017 , the Company had a federal net operating loss carryforward of $21.3 million , which will begin to expire in 2032 and a federal tax credit carryforward of $1.3 million , which will begin to expire in 2022. In addition, the Company had a $3.1 million alternative minimum tax credit carryforward that can be carried forward indefinitely, which is now carried as tax receivables since under new federal law of the Company expects to recover the entire amount by the end of 2021 via reduction of regular tax liability or refund. In addition, at December 31, 2017 , the Company had a federal net operating loss carryforward of $7.6 million relating to its acquisition of Downers Grove National Bank, which is subject to utilization limitations under Section 382 of the Internal Revenue Code, and will begin to expire in 2030, and $225,000 of alternative minimum tax credit carryforward that does not expire and is subject to utilization limitations under Section 382 of the Internal Revenue Code. At December 31, 2017 , the Company had a state net operating loss carryforward for the State of Illinois of $70.2 million , which will begin to expire in 2022. At December 31, 2017, the Company early adopted ASU 2018-02and reclassified out of retained earnings and into accumulated other comprehensive income $60,000 of tax (benefit) that was recorded to income tax expense at December 22, 2017 due to re-measuring to 21% deferred taxes on available for sale securities. Unrecognized Tax Benefits A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: December 31, 2017 2016 Beginning of year $ 57 $ 108 Additions based on tax positions related to the current year 60 — Additions for tax positions of prior years 12 — Reductions due to the statute of limitations and reductions for tax positions of prior years — (51 ) End of year $ 129 $ 57 The Company does not expect the total amount of unrecognized tax benefits to significantly increase or decrease in the next twelve months. The Company recognizes interest and/or penalties related to income tax matters in income tax expense. At December 31, 2017 and 2016 , the Company has immaterial amounts accrued for potential interest and penalties. The Company and its subsidiary are subject to U.S. federal income tax as well as income tax of the various states where the Company does business. The Company is no longer subject to examination by the federal taxing authorities for years before 2014 and the Illinois taxing authorities for years before 2014.

Regulatory Matters (Notes)

Regulatory Matters (Notes)	12 Months Ended
	Dec. 31, 2017
Banking and Thrift [Abstract]
Regulatory Matters	Actual and required capital amounts and ratios were: Actual Required for Capital Adequacy Purposes To be Well-Capitalized under Prompt Corrective Action Provisions Amount Ratio Amount Ratio Amount Ratio December 31, 2017 Total capital (to risk-weighted assets): Consolidated $ 195,371 17.06 % $ 91,590 8.00 % N/A N/A BankFinancial, NA 188,582 16.48 91,572 8.00 $ 114,466 10.00 % Tier 1 (core) capital (to risk-weighted assets): Consolidated 187,005 16.33 68,692 6.00 N/A N/A BankFinancial, NA 180,216 15.74 68,679 6.00 91,572 8.00 Common Tier 1 (CET1) Consolidated 187,005 16.33 51,519 4.50 N/A N/A BankFinancial, NA 180,216 15.74 51,509 4.50 74,403 6.50 Tier 1 (core) capital (to adjusted average total assets): Consolidated 187,005 11.49 65,085 4.00 N/A N/A BankFinancial, NA 180,216 11.08 65,045 4.00 81,307 5.00 December 31, 2016 Total capital (to risk-weighted assets): Consolidated $ 193,845 16.96 % $ 91,414 8.00 % N/A N/A BankFinancial, NA 168,113 14.72 91,386 8.00 $ 114,232 10.00 % Tier 1 (core) capital (to risk-weighted assets): Consolidated 185,718 16.25 68,560 6.00 N/A N/A BankFinancial, NA 159,986 14.01 68,539 6.00 91,386 8.00 Common Tier 1 (CET1) Consolidated 185,718 16.25 51,420 4.50 N/A N/A BankFinancial, NA 159,986 14.01 51,404 4.50 74,251 6.50 Tier 1 (core) capital (to adjusted average total assets): Consolidated 185,718 11.92 62,306 4.00 N/A N/A BankFinancial, NA 159,986 10.27 62,303 4.00 77,879 5.00 The Company and the Bank have each adopted Regulatory Capital Plans that require the Bank to maintain a Tier 1 leverage ratio of at least 7.5% and a total risk-based capital ratio of at least 10.5% (including the Capital Conservation Buffer ("CCB")). The minimum capital ratios set forth in the Regulatory Capital Plans will be increased and other minimum capital requirements will be established if and as necessary. In accordance with the Regulatory Capital Plans, neither the Company nor the Bank will pursue any acquisition or growth opportunity, declare any dividend or conduct any stock repurchase that would cause the Bank's total risk-based capital ratio and/or its Tier 1 leverage ratio to fall below the established minimum capital levels or the capital levels required for capital adequacy plus the CCB. The minimum CCB in 2017 is 1.25% and will increase 0.625% annually through 2019 to 2.5%. In addition, the Company will continue to maintain its ability to serve as a source of financial strength to the Bank by holding at least $5.0 million of cash or liquid assets for that purpose. As of December 31, 2017 , the Bank and the Company were well-capitalized, with all capital ratios exceeding the well-capitalized requirement. There are no conditions or events that management believes have changed the Bank’s prompt corrective action capitalization category. The Bank is subject to regulatory restrictions on the amount of dividends it may declare and pay to the Company without prior regulatory approval, and to regulatory notification requirements for dividends that do not require prior regulatory approval.

Employee Benefit Plans (Notes)

Employee Benefit Plans (Notes)	12 Months Ended
	Dec. 31, 2017
Compensation and Retirement Disclosure [Abstract]
Employee Benefit Plans	Employee Stock Ownership Plan . On March 29, 2017, the ESOP was terminated and the ESOP repaid all amounts owing under the ESOP’s Term Loan Agreement with the Company (the “Share Acquisition Loan”). The ESOP repaid the Share Acquisition Loan by transferring 753,490 unallocated shares of the Company’s common stock to the Company in exchange for the full satisfaction of the Share Acquisition Loan, using the valuation method provided for in the ESOP. A total of 78,362 unallocated shares remained in the ESOP after the Share Acquisition Loan was repaid, and these shares were released and will be allocated to the accounts of eligible ESOP participants who were actively employed by the Bank as of March 29, 2017, based on their account balances. These transactions resulted in the recording of one-time, non-cash, non-tax deductible equity compensation expense of $1.1 million in the first quarter of 2017. The Share Acquisition Loan had no outstanding principal balance at December 31, 2017 and an outstanding principal balance of $10.8 million at December 31, 2016 . The Company made the Share Acquisition Loan to the ESOP in the original principal amount of $19.6 million in connection with the Company’s mutual to stock conversion in June of 2005. The proceeds of the Share Acquisition Loan were used by the ESOP to purchase 1,957,300 shares of the Company’s common stock issued in the subscription offering at a price of $10.00 per share. The Share Acquisition Loan was secured by a pledge of the acquired shares and the ESOP made annual loan payments with funds it received from the Bank’s discretionary contributions to the ESOP in subsequent years and dividends it received on unallocated shares. As loan payments were made, the Company recorded compensation expense based on the allocation of shares released. Contributions to the ESOP were $1.1 million and $1.5 million for the years ended December 31, 2017 and 2016 , including dividends and interest received on unallocated shares of $50,000 and $195,000 in 2017 and 2016 , respectively. Expense related to the ESOP, net of dividends and interest received on unallocated ESOP shares, was $1.1 million , $1.3 million and $1.0 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. Shares held by the ESOP were as follows: December 31, 2017 2016 Allocated to participants 1,203,810 1,125,448 Distributed to participants (317,914 ) (313,223 ) Unearned — 831,852 Total ESOP shares 885,896 1,644,077 Fair value of unearned shares $ — $ 12,328 Profit Sharing Plan/401(k) Plan . The Company has a defined contribution plan (“profit sharing plan”) covering all of its eligible employees. Employees are eligible to participate in the profit sharing plan after attainment of age 21 and completion of one year of service. The Company provides a match of $ 0.50 on each $1.00 of contribution up to 6% of eligible compensation beginning April 1, 2007. The Company may also contribute an additional amount annually at the discretion of the Board of Directors. Contributions totaling $328,000 , $330,000 , and $308,000 were made for the years ended December 31, 2017 , 2016 and 2015 , respectively.

Equity Incentive Plans (Notes)

Equity Incentive Plans (Notes)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Equity Incentive Plans	On June 27, 2006, the Company’s stockholders approved the BankFinancial Corporation 2006 Equity Incentive Plan, which authorized the Human Resources Committee of the Board of Directors of the Company to grant a variety of cash- and equity-based incentive awards, including stock options, stock appreciation rights, restricted stock, performance shares and other incentive awards, to employees and directors aggregating up to 3,425,275 shares of the Company’s common stock. The Plan provided that no awards may be granted under the Plan after the ten -year anniversary of the Effective Date. Consequently, no further awards will be granted under this Plan. As of December 31, 2016 , there were 1,752,156 stock options outstanding. During the year ended December 31, 2017 , all 1,752,156 stock options were exercised. All stock options were exercised on a net settlement basis, using a portion of the shares obtained upon exercise to pay the exercise price of the stock option. The net settlements resulted in the issuance of 280,554 shares of the Company's common stock. Certain employees also chose to use a portion of the net shares received upon the exercise to pay required tax withholdings. This reduced the net shares issued by 82,528 shares to 198,026 shares. There are no stock options available for grant at December 31, 2017 . For the years ended December 31, 2017 , 2016 and 2015 the Company recognized zero , $979,000 and $568,000 , respectively, of stock-based compensation expenses relating to the granting of stock options. A summary of the activity in the stock option plan for 2017 follows: Stock Options Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (1) Stock options outstanding at January 1, 2016 1,752,156 $ 12.30 1.48 $ 778 Stock options granted — — Stock options exercised — — Stock options outstanding at December 31, 2016 1,752,156 $ 12.30 0.48 $ 4,422 Stock options granted — — Stock options exercised (1,752,156 ) 12.30 Stock options outstanding at December 31, 2017 — $ — 0.00 $ — (1) Stock option aggregate intrinsic value represents the number of shares subject to options multiplied by the difference (if positive) in the closing market price of the common stock underlying the options on the date shown and the weighted average exercise price. The Human Resources Committee of the Board of Directors may grant shares of restricted stock to certain employees and directors of the Company. The awards generally vest annually over varying periods from three to five years and vesting is subject to acceleration in certain circumstances. The cost of such awards will be accrued ratably as compensation expense over such respective periods based on expected vesting dates. The Company recognized zero , $3,000 , and $70,000 of expenses relating to the grant of shares of restricted stock during the years ended December 31, 2017 , 2016 and 2015 , respectively. As of December 31, 2017 , the total unrecognized compensation cost related to unvested shares of restricted stock was $8,000 . The cost is expected to be recognized over a weighted average period of 9.1 months. There are no shares of restricted stock available for grant at December 31, 2017 . Restricted Stock Number of Shares (1) Weighted Average Fair Value at Grant Date Weighted Average Term to Vest (in years) Aggregate Intrinsic Value (2) Shares outstanding at January 1, 2016 7,934 $ 8.14 0.31 $ 100 Shares granted — — Shares vested (6,994 ) — Shares forfeited — — Shares outstanding at December 31, 2016 940 $ 8.14 0.74 $ 14 Shares granted — — Shares vested — — Shares forfeited — — Shares outstanding at December 31, 2017 940 $ 8.14 0.00 $ 14 (1) The end of period balances consist only of unvested shares. (2) Restricted stock aggregate intrinsic value represents the number of shares of restricted stock multiplied by the market price of the common stock underlying the outstanding shares on the date shown.

Loan Commitments and Other Off-

Loan Commitments and Other Off-Balance Sheet Activities (Notes)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Loan Commitments and Other Off-Balance Sheet Activities	The Company is party to various financial instruments with off-balance-sheet risk. The Company uses these financial instruments in the normal course of business to meet the financing needs of customers and to effectively manage exposure to interest rate risk. These financial instruments include commitments to extend credit, standby letters of credit, unused lines of credit, and commitments to sell loans. When viewed in terms of the maximum exposure, those instruments may involve, to varying degrees, elements of credit and interest rate risk in excess of the amount recognized in the consolidated statements of financial condition. Credit risk is the possibility that a counterparty to a financial instrument will be unable to perform its contractual obligations. Interest rate risk is the possibility that, due to changes in economic conditions, the Company’s net interest income will be adversely affected. The following is a summary of the contractual or notional amount of each significant class of off-balance-sheet financial instruments outstanding. The Company’s exposure to credit loss in the event of nonperformance by the counterparty for commitments to extend credit, standby letters of credit, and unused lines of credit is represented by the contractual notional amount of these instruments. The contractual or notional amounts are as follows: December 31, 2017 2016 Financial instruments wherein contractual amounts represent credit risk Commitments to extend credit $ 46,615 $ 91,172 Standby letters of credit 6,757 1,305 Unused lines of credit 129,207 125,332 Commitments to sell mortgages — — Commitments to extend credit are generally made for periods of 60 days or less. The fixed-rate loans commitment totaled $19.2 million with interest rates ranging from 3.00% to 6.00% and maturities ranging from 1 to 30 years. Since many of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. The Company evaluates each customer’s creditworthiness on a case-by-case basis. The amount of collateral obtained, if it is deemed necessary by the Company upon extension of credit, is based on management’s credit evaluation of the customers. The Bank, as a member of Visa USA, received 51,404 unrestricted shares of Visa, Inc. Class B common stock in connection with Visa, Inc.’s initial public offering in 2007, and 32,398 additional shares of Class B common stock, due to a stock split, that were deposited into a litigation escrow that Visa, Inc. established under its retrospective responsibility plan. The retroactive responsibility plan obligates all former Visa USA members to indemnify Visa USA, in proportion to their equity interests in Visa USA, for certain litigation losses and expenses, including settlement expenses, for the lawsuits covered by the retrospective responsibility plan. The primary method for discharging the indemnification obligations under the retrospective responsibility plan is funding the litigation escrow through a reduction of the ratio at which the Visa, Inc. Class B shares can be converted into publicly traded Class A common shares of Visa, Inc. Since the Class B shares were issued, Visa, Inc. has reduced the conversion ratio to provide additional funding for the litigation escrow. Class B shares can only be transferred to other financial institutions until the underlying litigation is finally resolved, and the transfers that have occurred to date have involved material discounts. Due to the restrictions that the retrospective responsibility plan imposes on the Company’s Visa, Inc. Class B shares, the Company has not recorded the Class B shares as an asset.

Fair Value (Notes)

Fair Value (Notes)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value	Fair value is the exchange price that would be received for an asset or paid to transfer a liability (exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. There are three levels of inputs that may be used to measure fair values: • Level 1 – Quoted prices (unadjusted) for identical assets or liabilities in active markets that the entity has the ability to access as of the measurement date. • Level 2 – Significant other observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data. • Level 3 – Significant unobservable inputs that reflect a company’s own assumptions about the assumptions that market participants would use in pricing an asset or liability. The Company used the following methods and significant assumptions to estimate the fair value of each type of financial instrument: Securities : The fair values of marketable equity securities are generally determined by quoted prices, in active markets, for each specific security (Level 1). If Level 1 measurement inputs are not available for a marketable equity security, we determine its fair value based on the quoted price of a similar security traded in an active market (Level 2). The fair values of debt securities are generally determined by matrix pricing, which is a mathematical technique widely used in the industry to value debt securities without relying exclusively on quoted prices for the specific securities, but rather by relying on the securities’ relationship to other benchmark quoted securities (Level 2). Impaired Loans: The fair value of impaired loans with specific allocations of the allowance for loan losses is generally based on recent real estate appraisals. These appraisals may utilize a single valuation approach or a combination of approaches including comparable sales and the income approach. Adjustments are routinely made in the appraisal process by the independent appraisers to adjust for differences between the comparable sales and income data available for similar loans and collateral underlying such loans. Non-real estate collateral may be valued using an appraisal, net book value per the borrower’s financial statements, or aging reports, adjusted or discounted based on management’s historical knowledge, changes in market conditions from the time of the valuation, and management’s expertise and knowledge of the client and client’s business, resulting in a Level 3 fair value classification. Impaired loans are evaluated on a quarterly basis for additional impairment and adjusted in accordance with the allowance policy. Other Real Estate Owned: Assets acquired through or instead of loan foreclosure are initially recorded at fair value less costs to sell when acquired, establishing a new cost basis. These assets are subsequently accounted for at lower of cost or fair value less estimated costs to sell. Fair value is commonly based on recent real estate appraisals which are updated no less frequently than annually. These appraisals may utilize a single valuation approach or a combination of approaches including comparable sales and the income approach with data from comparable properties. Adjustments are routinely made in the appraisal process by the independent appraisers to adjust for differences between the comparable sales and income data available. Real estate owned properties are evaluated on a quarterly basis for additional impairment and adjusted accordingly. The following table sets forth the Company’s financial assets that were accounted for at fair value and are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. Fair Value Measurements Using Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fair Value December 31, 2017 Securities: Certificates of deposit $ — $ 75,916 $ — $ 75,916 Equity mutual fund 499 — — 499 Mortgage-backed securities – residential — 12,472 — 12,472 Collateralized mortgage obligations – residential — 4,486 — 4,486 SBA-guaranteed loan participation certificates — 10 — 10 $ 499 $ 92,884 $ — $ 93,383 December 31, 2016 Securities: Certificates of deposit $ — $ 85,938 $ — $ 85,938 Equity mutual fund 499 — — 499 Mortgage-backed securities - residential — 15,184 — 15,184 Collateralized mortgage obligations – residential — 5,574 — 5,574 SBA-guaranteed loan participation certificates — 17 — 17 $ 499 $ 106,713 $ — $ 107,212 The following table sets forth the Company’s assets that were measured at fair value on a non-recurring basis: Fair Value Measurement Using Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fair Value December 31, 2017 Other real estate owned: One–to–four family residential real estate $ — $ — $ 102 $ 102 Nonresidential real estate — — 814 814 Other real estate owned $ — $ — $ 916 $ 916 December 31, 2016 Impaired loans: Nonresidential real estate $ — $ — $ 234 $ 234 Impaired loans $ — $ — $ 234 $ 234 Other real estate owned: One–to–four family residential real estate $ — $ — $ 1,282 $ 1,282 Nonresidential real estate — — 553 553 Land — — 47 47 Other real estate owned $ — $ — $ 1,882 $ 1,882 At December 31, 2017 there were no impaired loans that were measured for impairment using the fair value of the collateral for collateral–dependent loans and which had specific valuation allowance, compared to one impaired loan with a carrying amount of $260,000 and a valuation allowance of $26,000 at December 31, 2016 , resulting in a decrease in the provision for loan losses of $26,000 for the year ended December 31, 2017 , compared to an decrease in the provision for loan losses of $18,000 for the year ended December 31, 2016 . OREO is carried at the lower of cost or fair value less costs to sell, had a carrying value of $1.2 million less a valuation allowance of $261,000 , or $916,000 , at December 31, 2017 , compared to $2.3 million less a valuation allowance of $434,000 , or $1.9 million at December 31, 2016 . There were $333,000 and $314,000 of valuation allowance additions charged to expense of OREO recorded for the years ended December 31, 2017 and 2016 , respectively. The following table presents quantitative information, based on certain empirical data with respect to Level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis at December 31, 2017 : Fair Value Valuation Technique Unobservable Input Range (Weighted Average) Other real estate owned One-to-four family residential real estate $ 102 Sales comparison Discount applied to valuation 5.6% Nonresidential real estate 814 Sales comparison Comparison between sales and income approaches -3.66% to 15.22% (11.0%) $ 916 The following table presents quantitative information, based on certain empirical data with respect to Level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis at December 31, 2016 : Fair Value Valuation Technique Unobservable Input Range (Weighted Average) Impaired loans Nonresidential real estate $ 234 Sales comparison Comparison between sales and income approaches -10.2% Income approach Cap Rate 8.5% $ 234 Other real estate owned One-to-four family residential real estate $ 1,282 Sales comparison Discount applied to valuation 8.62% to 20.04% (11.9%) Nonresidential real estate 553 Sales comparison Comparison between sales and income approaches -3.22% to 4.58% (3.7%) Land 47 Sales comparison Discount applied to valuation 5.74% to 31.60% (25.2%) $ 1,882 The carrying amount and estimated fair value of financial instruments is as follows: Fair Value Measurements at December 31, 2017 Using: Carrying Amount Level 1 Level 2 Level 3 Total Financial assets Cash and cash equivalents $ 127,592 $ 13,572 $ 114,020 $ — $ 127,592 Securities 93,383 499 92,884 — 93,383 Loans receivable, net of allowance for loan losses 1,314,651 — 1,323,139 — 1,323,139 FHLB and FRB stock 8,290 — — — N/A Accrued interest receivable 4,619 — 4,619 — 4,619 Financial liabilities Noninterest-bearing demand deposits $ 234,354 $ — $ 234,354 $ — $ 234,354 NOW and money market accounts 589,238 589,238 589,238 Savings deposits 160,501 — 160,501 — 160,501 Certificates of deposit 355,958 — 353,969 — 353,969 Borrowings 60,768 — 60,627 — 60,627 Accrued interest payable 147 — 147 — 147 Fair Value Measurements at December 31, 2016 Using: Carrying Amount Level 1 Level 2 Level 3 Total Financial assets Cash and cash equivalents $ 96,684 $ 13,053 $ 83,631 $ — $ 96,684 Securities 107,212 499 106,713 — 107,212 Loans receivable, net of allowance for loan losses 1,312,952 — 1,322,713 234 1,322,947 FHLB and FRB stock 11,650 — — — N/A Accrued interest receivable 4,381 — 4,381 — 4,381 Financial liabilities Noninterest-bearing demand deposits $ 249,539 $ — $ 249,539 $ — $ 249,539 NOW and money market accounts 578,237 578,237 578,237 Savings deposits 160,002 — 160,002 — 160,002 Certificates of deposit 351,612 — 350,593 — 350,593 Borrowings 51,069 — 50,015 — 50,015 Accrued interest payable 102 — 102 — 102 For purposes of the above, the following assumptions were used: Cash and Cash Equivalents : The estimated fair values for cash and cash equivalents are based on their carrying value due to the short-term nature of these assets. Loans : The estimated fair value for loans has been determined by calculating the present value of future cash flows based on the current rate the Company would charge for similar loans with similar maturities, applied for an estimated time period until the loan is assumed to be repriced or repaid. The methods utilized to estimate fair value of loans do not necessarily represent an exit price. The estimated fair values of loans held-for-sale are based on outstanding commitments from third-party investors. FHLB and FRB Stock : It is not practicable to determine the fair value of FHLB and FRB stock due to the restrictions placed on its transferability. Deposit Liabilities : The estimated fair value for certificates of deposit has been determined by calculating the present value of future cash flows based on estimates of rates the Company would pay on such deposits, applied for the time period until maturity. The estimated fair values of noninterest-bearing demand, NOW, money market, and savings deposits are assumed to approximate their carrying values as management establishes rates on these deposits at a level that approximates the local market area. Additionally, these deposits can be withdrawn on demand. Borrowings : The estimated fair values of advances from the FHLB and notes payable are based on current market rates for similar financing. The estimated fair value of securities sold under agreements to repurchase is assumed to equal its carrying value due to the short-term nature of the liability. Accrued Interest : The estimated fair values of accrued interest receivable and payable are assumed to equal their carrying value. Off - Balance-Sheet Instruments : Off-balance-sheet items consist principally of unfunded loan commitments, standby letters of credit, and unused lines of credit. The estimated fair values of unfunded loan commitments, standby letters of credit, and unused lines of credit are not material. While the above estimates are based on management’s judgment of the most appropriate factors, as of the balance sheet date, there is no assurance that the estimated fair values would have been realized if the assets were disposed of or the liabilities settled at that date, since market values may differ depending on the various circumstances. The estimated fair values would also not apply to subsequent dates. In addition, other assets and liabilities that are not financial instruments, such as premises and equipment, are not included in the above disclosures.

Company Only Condensed Financia

Company Only Condensed Financial Information (Notes)	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Company Only Condensed Financial Information	Condensed financial information of BankFinancial Corporation as of December 31, 2017 and 2016 and for the three years ended December 31, 2017 follows: Condensed Statements of Financial Condition December 31, 2017 2016 Assets Cash in subsidiary $ 6,393 $ 14,543 Loan receivable from ESOP — 10,767 Investment in subsidiary 188,873 176,756 Deferred tax asset 2,076 2,367 Other assets 3,307 347 $ 200,649 $ 204,780 Liabilities and Stockholders' Equity Accrued expenses and other liabilities $ 3,015 $ — Total stockholders’ equity 197,634 204,780 $ 200,649 $ 204,780 Condensed Statements of Operations For the years ended December 31, 2017 2016 2015 Interest income $ 110 $ 503 $ 544 Dividends from subsidiary 10,629 16,888 19,710 Other expense 1,693 1,846 1,536 Income before income tax and undistributed subsidiary income 9,046 15,545 18,718 Income tax expense (benefit) 290 (502 ) (783 ) Income before equity in undistributed subsidiary income 8,756 16,047 19,501 Equity in undistributed subsidiary income (excess distributions) 248 (8,545 ) (10,826 ) Net income $ 9,004 $ 7,502 $ 8,675 Condensed Statements of Cash Flows For the years ended December 31, 2017 2016 2015 Cash flows from operating activities Net income $ 9,004 $ 7,502 $ 8,675 Adjustments: Equity in undistributed subsidiary excess distributions (248 ) 8,545 10,826 Change in other assets (2,712 ) (497 ) (793 ) Change in accrued expenses and other liabilities 3,015 — — Net cash from operating activities 9,059 15,550 18,708 Cash flows from investing activities Principal payments received on ESOP loan — 1,032 992 Net cash from investing activities — 1,032 992 Cash flows from financing activities Net exercise of stock options (1,237 ) — — Repurchase and retirement of common stock (10,819 ) (13,215 ) (9,970 ) Cash dividends paid on common stock (5,153 ) (4,133 ) (4,145 ) Net cash used in financing activities (17,209 ) (17,348 ) (14,115 ) Net change in cash in subsidiary (8,150 ) (766 ) 5,585 Beginning cash in subsidiary 14,543 15,309 9,724 Ending cash in subsidiary $ 6,393 $ 14,543 $ 15,309

Selected Quarterly Financial Da

Selected Quarterly Financial Data (unaudited) (Notes)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (unaudited)	For the year ended December 31, 2017 First Quarter Second Quarter Third Quarter Fourth Quarter Interest income $ 13,362 $ 13,649 $ 14,121 $ 15,047 Interest expense 1,276 1,456 1,615 1,742 Net interest income 12,086 12,193 12,506 13,305 Provision for (recovery of) loan losses 161 49 (225 ) (72 ) Net interest income 11,925 12,144 12,731 13,377 Noninterest income 1,544 1,607 1,623 1,634 Noninterest expense 11,266 9,607 10,200 9,318 Income before income taxes 2,203 4,144 4,154 5,693 Income tax expense 322 1,572 594 4,702 Net income $ 1,881 $ 2,572 $ 3,560 $ 991 Basic earnings per common share $ 0.10 $ 0.14 $ 0.20 $ 0.06 Diluted earnings per common share 0.10 0.14 0.20 0.06 The Company recorded net income of $1.0 million , or $0.06 per common share, for the fourth quarter of 2017 . The Company’s net interest income before provision for loan losses was $13.3 million due to stronger loan originations and improved asset quality, which was offset by increased interest bearing liabilities at higher cost of funds. The Company’s fourth quarter 2017 operating results included a $2.5 million provision for taxes related to Tax Cuts and Jobs Act of 2017. For the year ended December 31, 2016 First Second Third Fourth Interest income $ 12,759 $ 12,581 $ 12,845 $ 12,743 Interest expense 856 952 1,014 1,148 Net interest income 11,903 11,629 11,831 11,595 Provision for (recovery of) loan losses (490 ) 1,315 (525 ) (539 ) Net interest income 12,393 10,314 12,356 12,134 Noninterest income 1,594 1,537 1,637 1,777 Noninterest expense 10,930 10,506 9,912 10,194 Income before income taxes 3,057 1,345 4,081 3,717 Income tax expense 1,153 514 1,573 1,458 Net income $ 1,904 $ 831 $ 2,508 $ 2,259 Basic earnings per common share $ 0.10 $ 0.04 $ 0.13 $ 0.12 Diluted earnings per common share 0.10 0.04 0.13 0.12 The Company recorded net income of $2.3 million , or $0.12 per common share, for the fourth quarter of 2016. The Company’s net interest income before provision for loan losses was $11.6 million due to stronger loan originations and improved asset quality. The Company’s fourth quarter 2016 operating results included a $539,000 recovery of loan losses. Noninterest expense included gains on OREO sales of $113,000 and $177,000 of nonperforming asset management and OREO expense.

Summary of Significant Accoun27

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation : BankFinancial Corporation, a Maryland corporation headquartered in Burr Ridge, Illinois (the “Company”), is the owner of all of the issued and outstanding capital stock of BankFinancial, National Association (the “Bank”).
Principles of Consolidation	Principles of Consolidation : The consolidated financial statements include the accounts of and transactions of BankFinancial Corporation, the Bank, and the Bank’s wholly-owned subsidiaries, Financial Assurance Services, Inc. and BFIN Asset Recovery Company, LLC (formerly BF Asset Recovery Corporation) (collectively, “the Company”) and have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). All significant intercompany accounts and transactions have been eliminated.
Use of Estimates	Use of Estimates : To prepare financial statements in conformity with GAAP, management makes estimates and assumptions based on available information. These estimates and assumptions affect the amounts reported in the financial statements and the disclosures provided, and actual results could differ.
Cash Flows	Interest-bearing Deposits in Other Financial Institutions : Interest-bearing deposits in other financial institutions maturing in less than 90 days are carried at cost. Cash Flows : Cash and cash equivalents include cash, deposits with other financial institutions maturing in less than 90 days, and daily federal funds sold. Net cash flows are reported for customer loan and deposit transactions, interest bearing deposits in other financial institutions, borrowings, and advance payments by borrowers for taxes and insurance.
Securities	Securities : Debt securities are classified as available-for-sale when they might be sold before maturity. Equity securities with readily determinable fair values are classified as available-for-sale. Securities available-for-sale are carried at fair value, with unrealized holding gains and losses reported in other comprehensive income (loss), net of tax. Interest income includes amortization of purchase premium or discount. Premiums and discounts on securities are amortized on the level-yield method without anticipating prepayments, except for mortgage-backed securities where prepayments are anticipated. Gains and losses on sales are based on the amortized cost of the security sold. Declines in the fair value of securities below their cost that are other-than-temporary are reflected as realized losses. In determining if losses are other-than-temporary, management considers: (1) the length of time and extent that fair value has been less than cost or adjusted cost, as applicable, (2) the financial condition and near term prospects of the issuer, and (3) whether the Company has the intent to sell the debt security or it is more likely than not that the Company will be required to sell the debt security before the anticipated recovery.
Federal Home Loan Bank Stock	Federal Home Loan Bank (“FHLB”) Stock : The Bank is a member of the FHLB system. Members are required to own a certain amount of stock based on the level of borrowings and other factors, and may invest in additional amounts. FHLB stock is carried at cost, classified as a restricted security, and periodically evaluated for impairment based on ultimate recovery of par value. Both cash and stock dividends are reported as income.
Loans And Loan Income	Loans and Loan Income : Loans that management has the intent and ability to hold for the foreseeable future or until maturity or payoff are reported at the principal balance outstanding, net of the allowance for loan losses, premiums and discounts on loans purchased, and net deferred loan costs. Interest income on loans is recognized in income over the term of the loan based on the amount of principal outstanding. Premiums and discounts associated with loans purchased are amortized over the contractual term of the loan using the level–yield method. Loan origination fees, net of certain direct origination costs, are deferred and recognized in interest income using the level‑yield method without anticipating prepayments. Interest income is reported on the interest method. Interest income is discontinued at the time a loan is 90 days past due or when we do not expect to receive full payment of interest or principal. Past due status is based on the contractual terms of the loan. All interest accrued but not received for loans that have been placed on nonaccrual status is reversed against interest income. Interest received on such loans is accounted for on the cash–basis or cost–recovery method until qualifying for return to accrual status. Once a loan is placed on nonaccrual status, the borrower must generally demonstrate at least six months of payment performance before the loan is eligible to return to accrual status. Generally, the Company utilizes the “90 days delinquent, still accruing” category of loan classification when: (1) the loan is repaid in full shortly after the period end date; (2) the loan is well secured and there are no asserted or pending legal barriers to its collection; or (3) the borrower has remitted all scheduled payments and is otherwise in substantial compliance with the terms of the loan, but the processing of payments actually received or the renewal of a loan has not occurred for administrative reasons.
Impaired Loans	Impaired Loans: Impaired loans consist of nonaccrual loans and troubled debt restructurings (“TDRs”). A loan is considered impaired when, based on current information and events, management believes that it is probable that we will be unable to collect all amounts due (both principal and interest) according to the original contractual terms of the loan agreement. Once a loan is determined to be impaired, the amount of impairment is measured based on the loan's observable fair value, the fair value of the underlying collateral less selling costs if the loan is collateral-dependent, or the present value of expected future cash flows discounted at the loan's effective interest rate. If the measurement of the impaired loan is less than the recorded investment in the loan, the bank's allowance for the impaired collateral dependent loan under ASC 310-10-35 is based on fair value (less costs to sell), but the charge-off (the confirmed “loss”) is based on the appraised value. The remaining recorded investment in the loan after the charge-off will have a loan loss allowance for the amount by which the estimated fair value of the collateral (less costs to sell) is less than its appraised value. Impaired loans with specific reserves are reviewed quarterly for any changes that would affect the specific reserve. Any impaired loan for which a determination has been made that the economic value is permanently reduced is charged-off against the allowance for loan losses to reflect its current economic value in the period in which the determination has been made. At the time a collateral-dependent loan is initially determined to be impaired, we review the existing collateral appraisal. If the most recent appraisal is greater than a year old, a new appraisal is obtained on the underlying collateral. Appraisals are updated with a new independent appraisal at least annually and are formally reviewed by our internal appraisal department upon receipt of a new appraisal. All impaired loans and their related reserves are reviewed and updated each quarter. With an immaterial number of exceptions, all appraisals and internal reviews are current under this methodology at December 31, 2017 .
Troubled Debt Restructurings	Troubled Debt Restructurings : A loan is classified as a troubled debt restructuring when a borrower is experiencing financial difficulties that leads to a restructuring of the loan, and the Company grants concessions to the borrower in the restructuring that it would not otherwise consider. These concessions may include rate reductions, principal forgiveness, extension of maturity date and other actions intended to minimize potential losses. In determining whether a debtor is experiencing financial difficulties, the Company considers if the debtor is in payment default or would be in payment default in the foreseeable future without the modification, the debtor declared or is in the process of declaring bankruptcy, there is substantial doubt that the debtor will continue as a going concern, the debtor has securities that have been or are in the process of being delisted, the debtor's entity-specific projected cash flows will not be sufficient to service any of its debt, or the debtor cannot obtain funds from sources other than the existing creditors at a market rate for debt with similar risk characteristics. In determining whether the Company has granted a concession, the Company assesses, if it does not expect to collect all amounts due, whether the current value of the collateral will satisfy the amounts owed, whether additional collateral or guarantees from the debtor will serve as adequate compensation for other terms of the restructuring, and whether the debtor otherwise has access to funds at a market rate for debt with similar risk characteristics. Periodically, the Company will restructure a note into two separate notes (A/B structure), charging off the entire B portion of the note. The A note is structured with appropriate loan-to-value and cash flow coverage ratios that provide for a high likelihood of repayment. The A note is classified as a nonperforming note until the borrower has displayed a historical payment performance for a reasonable time prior to and subsequent to the restructuring. A period of sustained repayment for at least six months generally is required to return the note to accrual status provided that management has determined that the performance is reasonably expected to continue. The A note will be classified as a restructured note (either performing or nonperforming) through the calendar year of the restructuring that the historical payment performance has been established.
Allowance for Loan Losses	Allowance for Loan Losses: The Company establishes provisions for loan losses, which are charged to the Company’s results of operations to maintain the allowance for loan losses to absorb probable incurred credit losses in the loan portfolio. In determining the level of the allowance for loan losses, the Company considers past and current loss experience, trends in classified loans, evaluations of real estate collateral, current economic conditions, volume and type of lending, adverse situations that may affect a borrower’s ability to repay a loan and the levels of nonperforming and other classified loans. The amount of the allowance is based on estimates and the ultimate losses may vary from the estimates as more information becomes available or events change. The Company provides for loan losses based on the allowance method. Accordingly, all loan losses are charged to the related allowance and all recoveries are credited to it. Additions to the allowance for loan losses are provided by charges to income based on various factors that, in our judgment, deserve current recognition in estimating probable incurred credit losses. The Company reviews the loan portfolio on an ongoing basis and makes provisions for loan losses on a quarterly basis to maintain the allowance for loan losses in accordance with GAAP. The allowance for loan losses consists of two components: • specific allowances established for any impaired residential non-owner occupied mortgage, multi-family mortgage, nonresidential real estate, construction and land, commercial, and commercial lease loans for which the recorded investment in the loan exceeds the measured value of the loan; and • general allowances for loan losses for each loan class based on historical loan loss experience; and adjustments to historical loss experience (general allowances), maintained to cover uncertainties that affect our estimate of probable incurred credit losses for each loan class. The adjustments to historical loss experience are based on our evaluation of several factors, including levels of, and trends in, past due and classified loans; levels of, and trends in, charge–offs and recoveries; trends in volume and terms of loans, including any credit concentrations in the loan portfolio; experience and ability of lending management and other relevant staff; and national and local economic trends and conditions. The Company evaluates the allowance for loan losses based upon the combined total of the specific and general components. Generally, when the loan portfolio increases, absent other factors, the allowance for loan loss methodology results in a higher dollar amount of estimated probable incurred credit losses than would be the case without the increase. Conversely, when the loan portfolio decreases, absent other factors, the allowance for loan loss methodology generally results in a lower dollar amount of estimated probable losses than would be the case without the decrease. The loss ratio used in computing the required general loan loss reserve allowance for a given class of loan consists of (i) the actual loss ratio (measured on a weighted, rolling twelve-quarter basis), (ii) the change in credit quality within the specific loan class during the period, (iii) the actual inherent risk factor assigned to the specific loan class and (iv) the actual concentration of risk factor assigned to the specific loan class (collectively, the “Specific Loan Class Risk Factors”). The Specific Loan Class Risk Factors are weighted equally in the calculation. In addition, two additional quantitative factors, the National Economic risk factor and the Local Economic risk factor, are also components of the computation but are given different weightings in their computation due to their relative applicability to the specific loan class in the context of the effect of national and local economic conditions on their risk profile and performance.
Uncollected Interest	When a loan is on non-accrual status and the ultimate collectability of the total principal of an impaired loan is in doubt, all payments are applied to principal under the cost recovery method. Alternatively, when a loan is on non-accrual status but there is doubt concerning only the ultimate collectability of interest, contractual interest is credited to interest income only when received, under the cash basis method pursuant to the provisions of FASB ASC 310–10, as applicable. In all cases, the average balances are calculated based on the month–end balances of the financing receivables within the period reported pursuant to the provisions of FASB ASC 310–10, as applicable.
Mortgage Servicing Rights	Mortgage Servicing Rights : Mortgage servicing rights are recognized separately when they are acquired through sales of loans. When mortgage loans are sold, servicing rights are initially recorded at fair value and gains on sales of loans are recorded in the statement of operations. Fair value is based on market prices for comparable mortgage servicing contracts, when available, or alternatively, is based on a valuation model that calculates the present value of estimated future net servicing income. The valuation model incorporates assumptions that market participants would use in estimating future net servicing income, such as the servicing cost per loan, the discount rate, the escrow float rate, an inflation rate, ancillary income, prepayment speeds and default rates and losses. The Company compares the valuation model inputs and results to published industry data in order to validate the model results and assumptions. All classes of servicing assets are subsequently measured using the amortization method which requires servicing rights to be amortized into noninterest income in proportion to, and over the period of, the estimated future net servicing income of the underlying loans. Servicing assets are evaluated for impairment based upon the fair value of the rights as compared to carrying amount. Impairment is determined by stratifying rights into groupings based on predominant risk characteristics, such as interest rate, loan type and investor type. Impairment is recognized through a valuation allowance for an individual grouping, to the extent that fair value is less than the carrying amount. If the Company later determines that all or a portion of the impairment no longer exists for a particular grouping, a reduction of the allowance may be recorded as an increase to income. Changes in valuation allowances are reported with amortization and impairment of servicing assets on the statement of operations. The fair values of servicing rights are subject to significant fluctuations as a result of changes in estimated and actual prepayment speeds and default rates and losses. Servicing fee income that is reported on the statement of operations as loan servicing fees is recorded for fees earned for servicing loans. The fees are based on a contractual percentage of the outstanding principal; or a fixed amount per loan and are recorded as income when earned. Late fees and ancillary fees related to loan servicing are not material.
Other Real Estate Owned	Other Real Estate Owned ("OREO") : Foreclosed assets are initially recorded at fair value less cost to sell when acquired, establishing a new cost basis. Physical possession of residential real estate property collateralizing a consumer mortgage loan occurs when the legal title is obtained upon completion of foreclosure or when the borrower conveys all interest in the property to satisfy the loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. These assets are subsequently accounted for at a lower of cost or fair value less estimated cost to sell. If fair value declines subsequent to foreclosure, a valuation allowance is recorded through expense. Operating expenses, gains and losses on disposition, and changes in the valuation allowance are reported in noninterest expense as operations of other real estate owned.
Premises and Equipment	Premises and Equipment : Land is carried at cost. Premises and equipment are stated at cost less accumulated depreciation. Depreciation is included in noninterest expense and is computed on the straight-line method over the estimated useful lives of the assets. Useful lives are estimated to be 25 to 40 years for buildings and improvements that extend the life of the original building, ten to 20 years for routine building improvements, five to 15 years for furniture and equipment, two to five years for computer hardware and software and no greater than four years on automobiles. The cost of maintenance and repairs is charged to expense as incurred and significant repairs are capitalized.
Goodwill and Other Intangible Assets	Other Intangible Assets : Intangible assets acquired in a purchase business combination with definite useful lives are amortized over their estimated useful lives to their estimated residual values. Core deposit intangible assets (“CDI”), are recognized at the time of acquisition based on valuations prepared by independent third parties or other estimates of fair value. In preparing such valuations, variables such as deposit servicing costs, attrition rates, and market discount rates are considered. CDI assets are amortized to expense over their useful lives.
Bank Owned Life Insurance	Bank Owned Life Insurance: The Company has purchased life insurance policies on certain key executives. The Company owned life insurance is recorded at the amount that can be realized under the insurance contract at the balance sheet date, which is the cash surrender value adjusted for other charges or other amounts due that are probable at settlement.
Long-Term Assets	Long-Term Assets : Premises and equipment, core deposit and other intangible assets, and other long-term assets are reviewed for impairment when events indicate that their carrying amount may not be recoverable from future undiscounted cash flows. If impaired, the assets are recorded at fair value.
Loan Commitments and Related Financial Instruments	Loan Commitments and Related Financial Instruments : Financial instruments include off-balance-sheet credit instruments, such as commitments to make loans and commercial letters of credit, issued to meet customer financing needs. The face amount for these items represents the exposure to loss, before considering customer collateral or ability to repay. Such financial instruments are recorded when they are funded.
Income Taxes	Income Taxes : Income tax expense is the total of the current year income tax due or refundable and the change in deferred tax assets and liabilities. Under GAAP, a deferred tax asset valuation allowance is required to be recognized if it is “more likely than not” that the deferred tax asset will not be realized. The determination of the realizability of the deferred tax assets is highly subjective and dependent upon judgment concerning management’s evaluation of both positive and negative evidence, the forecasts of future taxable income, applicable tax planning strategies, and assessments of current and future economic and business conditions. The Company considers both positive and negative evidence regarding the ultimate realizability of our deferred tax assets. Examples of positive evidence may include the existence, if any, of taxes paid in available carry-back years and the likelihood that taxable income will be generated in future periods. Examples of negative evidence may include a cumulative loss in the current year and prior two years and negative general business and economic trends. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period of the enactment date. This analysis is updated quarterly and adjusted as necessary. At December 31, 2017 , the Company had a net deferred tax asset of $12.6 million . A tax position is recognized as a benefit only if it is "more likely than not" that the tax position would be sustained in a tax examination, presuming that a tax examination will occur. The amount recognized is the largest amount of tax benefit that is greater than 50% likely to be realized on examination. For tax positions not meeting the "more likely than not" test, no tax benefit is recorded.
Retirement Plans	Retirement Plans : Employee 401(k) and profit sharing plan expense is the amount of matching contributions and any annual discretionary contribution made at the discretion of the Company’s Board of Directors. Deferred compensation expense allocates the benefits over years of service.
Employee Stock Ownership Plan (ESOP)	Employee Stock Ownership Plan (“ESOP”) : The cost of shares issued to the ESOP, but not yet allocated to participants, was shown as a reduction of stockholders’ equity. Compensation expense is based on the market price of shares as they are committed to be released to participant accounts. Dividends on allocated ESOP shares reduce retained earnings; dividends on unearned ESOP shares reduce debt and accrued interest.
Earnings (Loss) Per Common Share	Earnings per Common Share : Basic earnings per common share is net income divided by the weighted average number of common shares outstanding during the period. ESOP shares are considered outstanding for this calculation unless unearned. Diluted earnings per common share is net income divided by the weighted average number of common shares outstanding during the period plus the dilutive effect of restricted stock shares and the additional potential shares issuable under stock options.
Loss Contingencies	Loss Contingencies : Loss contingencies, including claims and legal actions arising in the ordinary course of business, are recorded as liabilities when the likelihood of loss is probable and an amount or range of loss can be reasonably estimated. Management does not believe that there are such matters that will have a material effect on the financial statements as of December 31, 2017 .
Restrictions on Cash	Restrictions on Cash : Cash on hand or on deposit with the Federal Reserve Bank that is required to meet regulatory reserve and clearing requirements.
Fair Value of Financial Instruments	Fair Values of Financial Instruments : Fair values of financial instruments are estimated using relevant market value information and other assumptions, as more fully disclosed in a separate note. Fair value estimates involve uncertainties and matters of significant judgment regarding interest rates, credit risk, prepayments, and other factors, especially in the absence of broad markets for particular items. Changes in assumptions or in market conditions could significantly affect the estimates.
Comprehensive Income (Loss)	Comprehensive Income : Comprehensive income consists of net income and other comprehensive income (loss). Other comprehensive income (loss) includes unrealized gains and losses on securities, net of tax, which are also recognized as separate components of stockholders’ equity.
Stock-based Compensation	Stock-based Compensation: Compensation cost is recognized for stock options and restricted stock awards issued to employees, based on the fair value of these awards at the date of grant. The Black-Scholes model is utilized to estimate the fair value of stock options, while the market price of the Company’s common stock at the date of grant is used for restricted stock awards. Compensation cost is recognized over the required service period, generally defined as the vesting period.
Transfers of Financial Assets	Transfers of Financial Assets: Transfers of financial assets are accounted for as sales when control over the assets has been relinquished. Control over transferred assets is deemed to be surrendered when the assets have been isolated from the Company, the transferee obtains the right (free of conditions that constrain it from taking advantage of that right) to pledge or exchange the transferred assets, and the Company does not maintain effective control over the transferred assets through an agreement to repurchase them before their maturity.
Operating Segments	Operating Segments: While management monitors the revenue streams of the various products and services, operations are managed and financial performance is evaluated on a Company-wide basis. Operating results are not reviewed by senior management to make resource allocation or performance decisions. Accordingly, all of the financial service operations are considered by management to be aggregated in one reportable operating segment.
Reclassifications	Reclassifications : Certain reclassifications have been made in the prior year’s financial statements to conform to the current year’s presentation.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the FASB issued an update (ASU No. 2014-09, “Revenue from Contracts with Customers”) creating FASB Topic 606, Revenue from Contracts with Customers. The guidance in this update affects any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of nonfinancial assets unless those contracts are within the scope of other standards (for example, insurance contracts or lease contracts). The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The guidance provides steps to follow to achieve the core principle. An entity should disclose sufficient information to enable users of financial statements to understand the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. Qualitative and quantitative information is required about contracts with customers, significant judgments and changes in judgments, and assets recognized from the costs to obtain or fulfill a contract. The amendments in this update become effective for annual periods and interim periods within those annual periods beginning after December 15, 2017. We have evaluated the impact of adopting the update and have concluded that it will not have a significant impact to our consolidated financial statements. The Company’s revenue streams that are in-scope of the update include: financed OREO sales; deposit fees, including ATM fees, overdraft fees, maintenance fees and dormancy fees; credit and debit card fees, and trust fees. For the in-scope revenue streams, our current revenue recognition would not be different than revenue recognition under the update. The Company has infrequently financed an OREO sale. Our customer contracts generally do not have performance obligations and fees are assessed and collected as the transaction occurs. The Company’s fee income is not material for any individual income stream. The consolidated financial statements will be impacted by new disclosures required by the update. In January 2016, the FASB issued an update (ASU No. 2016-01, “Financial Instruments–Recognition and Measurement of Financial Assets and Liabilities”). The new guidance is intended to improve the recognition and measurement of financial instruments by requiring: equity investments (other than equity method or consolidation) to be measured at fair value with changes in fair value recognized in net income; public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; separate presentation of financial assets and financial liabilities by measurement category and form of financial assets ( i.e., securities or loans and receivables) on the balance sheet or the accompanying notes to the financial statements; eliminating the requirement to disclose the fair value of financial instruments measured at amortized cost for organizations that are not public business entities; eliminating the requirement for non-public business entities to disclose the method(s) and significant assumptions used to estimate the fair value that is to be required to be disclosed for financial instruments measured at amortized cost on the balance sheet; and requiring a reporting organization to present separately in other comprehensive income the portion of the total change in fair value of a liability resulting from the change in the instrument-specific credit risk (also referred to as “own credit”) when the organization has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. The new guidance is effective for public business entities for fiscal years beginning after December 15, 2017. We have evaluated the impact of adopting the new guidance on the consolidated financial statements. Our finding is that the new pronouncement will not have a significant impact on our Statement of Operations as we only have one equity security that was valued at $499,000 at December 31, 2017 . In February 2016, the FASB issued ASU No. 2016-02, “Leases (Topic 842)” (“ASU 2016-02”). The standard requires a lessee to recognize assets and liabilities on the balance sheet for leases with lease terms greater than 12 months. ASU 2016-02 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018, and early adoption is permitted. We are currently evaluating the impact that the standard will have on our consolidated financial statements. Our preliminary finding is that the new pronouncement will not have a significant impact on our consolidated financial statements as the projected minimum lease payments under existing leases subject to the new pronouncement are less than one percent of our current total assets. In March 2016, the FASB issued ASU No. 2016-09, “Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting” (“ASU 2016-09”). The standard is intended to simplify several areas of accounting for share-based compensation arrangements, including the income tax impact, classification on the statement of cash flows and forfeitures. ASU 2016-09 was effective January 1, 2017. This new pronouncement affects the effective tax rate reported as existing vested stock options are exercised. The amount of the impact on the effective tax rate is determined by the number of stock options exercised and the stock price of the Company when the stock options are exercised. Excess tax benefits and deficiencies are recorded in the tax expense. In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments” (“ASU 2016-13”). These amendments require the measurement of all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. Financial institutions and other organizations will now use forward-looking information to better inform their credit loss estimates. Many of the loss estimation techniques applied today will still be permitted, although the inputs to those techniques will change to reflect the full amount of expected credit losses. In addition, the ASU amends the accounting for credit losses on available-for-sale debt securities and purchased financial assets with credit deterioration. ASU 2016-13 is effective for SEC filers for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019 ( i.e. , January 1, 2020, for calendar year entities). Early application will be permitted for all organizations for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. We are currently evaluating the impact that the standard will have on our consolidated financial statements. Our initial review indicates that we have maintained sufficient historical loan data to support the requirements of this pronouncement. In addition, we have begun tracking the average life of the various segments of our loan portfolio. We are currently evaluating various loss methodologies to determine their correlation to our various loan categories' historical performance. In March of 2017, the FASB issued ASU No. 2017-08, “Receivables-Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities” (“ASU 2017-08”). This guidance shortens the amortization period for premiums on certain callable debt securities to the earliest call date (with an explicit, noncontingent call feature that is callable at a fixed price and on a preset dates), rather than contractual maturity date as currently required under GAAP. The ASU does not impact instruments without preset call dates such as mortgage-backed securities. For instruments with contingent call features, once the contingency is resolved and the security is callable at a fixed price and preset date, the security is within the scope of the ASU. ASU 2017-08 is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years, and early adoption is permitted. Effective January 2017, we early adopted the pronouncement. Adoption of the new pronouncement was immaterial to the consolidated financial statements.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Reconciliation of Basic and Diluted Earnings Per Share	For the years ended December 31, 2017 2016 2015 Net income available to common stockholders $ 9,004 $ 7,502 $ 8,675 Average common shares outstanding 18,429,018 19,673,416 20,708,775 Less: Unearned ESOP shares (148,179 ) (682,362 ) (780,227 ) Unvested restricted stock shares (940 ) (3,103 ) (10,545 ) Weighted average common shares outstanding 18,279,899 18,987,951 19,918,003 Add - Net effect of dilutive stock options and unvested restricted stock 437 59,188 3,516 Weighted average dilutive common shares outstanding 18,280,336 19,047,139 19,921,519 Basic earnings per common share $ 0.49 $ 0.40 $ 0.44 Diluted earnings per common share $ 0.49 $ 0.39 $ 0.44 Number of antidilutive stock options excluded from the diluted earnings per share calculation — 536,459 536,459 Weighted average exercise price of anti-dilutive option shares $ — $ 12.99 $ 12.99

Securities (Tables)

Securities (Tables)	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Unrealized gains and losses recognized in accumulated other comprehensive income (loss)	The fair value of securities and the related gross unrealized gains and losses recognized in accumulated other comprehensive income is as follows: Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value December 31, 2017 Certificates of deposit $ 75,916 $ — $ — $ 75,916 Equity mutual fund 500 — (1 ) 499 Mortgage-backed securities - residential 11,969 520 (17 ) 12,472 Collateralized mortgage obligations - residential 4,481 16 (11 ) 4,486 SBA-guaranteed loan participation certificates 10 — — 10 $ 92,876 $ 536 $ (29 ) $ 93,383 December 31, 2016 Certificates of deposit $ 85,938 $ — $ — $ 85,938 Equity mutual fund 500 — (1 ) 499 Mortgage-backed securities - residential 14,561 644 (21 ) 15,184 Collateralized mortgage obligations - residential 5,587 15 (28 ) 5,574 SBA-guaranteed loan participation certificates 17 — — 17 $ 106,603 $ 659 $ (50 ) $ 107,212
Amortized cost and fair values of securities	Sales of securities were as follows: For the years ended December 31, 2017 2016 2015 Proceeds $ — $ 46 $ — Gross gains — 46 — Gross losses — — — The amortized cost and fair values of securities at December 31, 2017 by contractual maturity are shown below. Securities not due at a single maturity date are shown separately. Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. December 31, 2017 Amortized Cost Fair Value Due in one year or less $ 75,916 $ 75,916 Mortgage-backed securities - residential 11,969 12,472 Collateralized mortgage obligations - residential 4,481 4,486 SBA-guaranteed loan participation certificates 10 10 $ 92,376 $ 92,884
Securities with unrealized losses	Securities with unrealized losses at December 31, 2017 and 2016 not recognized in income are as follows: Less than 12 Months 12 Months or More Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss December 31, 2017 Equity mutual fund $ 499 $ (1 ) $ — $ — $ 499 $ (1 ) Mortgage-backed securities - residential — — 1,149 (17 ) 1,149 (17 ) Collateralized mortgage obligations - residential — — 2,083 (11 ) 2,083 (11 ) $ 499 $ (1 ) $ 3,232 $ (28 ) $ 3,731 $ (29 ) December 31, 2016 Equity mutual fund $ 499 $ (1 ) $ — $ — $ 499 $ (1 ) Mortgage-backed securities - residential 1,187 (21 ) — — 1,187 (21 ) Collateralized mortgage obligations - residential 3,691 (18 ) 1,028 (10 ) 4,719 (28 ) $ 5,377 $ (40 ) $ 1,028 $ (10 ) $ 6,405 $ (50 )

Loans Receivable (Tables)

Loans Receivable (Tables)	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Loans By Class Modified As Troubled Debt Restructurings With Payment Default	The following table presents TDRs for which there was a payment default within twelve months following the modification: For the years ended December 31, 2017 2016 Number of loans Recorded investment Number of loans Recorded investment One-to-four family residential real estate — $ — 2 $ 87
Loans Individually Evaluated For Impairment By Class Loans	The following tables present loans individually evaluated for impairment by class of loans: Loan Balance Recorded Investment Partial Charge-off Allowance for Loan Losses Allocated Average Investment in Impaired Loans Interest Income Recognized December 31, 2017 With no related allowance recorded One-to-four family residential real estate $ 5,049 $ 4,248 $ 806 $ — $ 4,212 $ 197 Multi-family mortgage 958 948 — — 847 41 $ 6,007 $ 5,196 $ 806 $ — $ 5,059 $ 238 Loan Balance Recorded Investment Partial Charge-off Allowance for Loan Losses Allocated Average Investment in Impaired Loans Interest Income Recognized December 31, 2016 With no related allowance recorded One-to-four family residential real estate $ 5,379 $ 4,548 $ 886 $ — $ 2,947 $ 70 One-to-four family residential real estate - non-owner occupied 503 386 119 — 251 9 Multi-family mortgage 787 787 — — 980 41 6,669 5,721 1,005 — 4,178 120 With an allowance recorded - Nonresidential real estate 262 260 21 26 164 — $ 6,931 $ 5,981 $ 1,026 $ 26 $ 4,342 $ 120
Troubled Debt Restructurings on Financing Receivables	The following table presents loans classified as TDRs: December 31, 2017 2016 One-to-four family residential real estate - Accrual $ — $ 205 One-to-four family residential real estate - Nonaccrual 17 136 $ 17 $ 341
Loans Receivable Based On Impairment Method	The following tables present the balance in the allowance for loan losses and the loans receivable by portfolio segment and based on impairment method: Allowance for loan losses Loan Balances Individually evaluated for impairment Collectively evaluated for impairment Total Individually evaluated for impairment Collectively evaluated for impairment Total December 31, 2017 One-to-four family residential real estate $ — $ 850 $ 850 $ 4,265 $ 93,549 $ 97,814 Multi-family mortgage — 3,849 3,849 949 587,434 588,383 Nonresidential real estate — 1,605 1,605 — 169,971 169,971 Construction and land — 32 32 — 1,358 1,358 Commercial loans — 1,357 1,357 — 152,552 152,552 Commercial leases — 655 655 — 310,076 310,076 Consumer — 18 18 — 1,597 1,597 $ — $ 8,366 $ 8,366 $ 5,214 $ 1,316,537 1,321,751 Net deferred loan origination costs 1,266 Allowance for loan losses (8,366 ) Loans, net $ 1,314,651 Allowance for loan losses Loan Balances Individually evaluated for impairment Collectively evaluated for impairment Total Individually evaluated for impairment Collectively evaluated for impairment Total December 31, 2016 One-to-four family residential real estate $ — $ 1,168 $ 1,168 $ 4,962 $ 130,256 $ 135,218 Multi-family mortgage — 3,647 3,647 787 542,100 542,887 Nonresidential real estate 26 1,768 1,794 260 181,892 182,152 Construction and land — 32 32 — 1,302 1,302 Commercial loans — 733 733 — 99,088 99,088 Commercial leases — 714 714 — 356,514 356,514 Consumer — 39 39 — 2,255 2,255 $ 26 $ 8,101 $ 8,127 $ 6,009 $ 1,313,407 1,319,416 Net deferred loan origination costs 1,663 Allowance for loan losses (8,127 ) Loans, net $ 1,312,952
Schedule of Accounts, Notes, Loans and Financing Receivable	Loans receivable are as follows: December 31, 2017 2016 One-to-four family residential real estate $ 97,814 $ 135,218 Multi-family mortgage 588,383 542,887 Nonresidential real estate 169,971 182,152 Construction and land 1,358 1,302 Commercial loans 152,552 99,088 Commercial leases 310,076 356,514 Consumer 1,597 2,255 1,321,751 1,319,416 Net deferred loan origination costs 1,266 1,663 Allowance for loan losses (8,366 ) (8,127 ) Loans, net $ 1,314,651 $ 1,312,952
Financing Receivable Credit Quality Indicators	As of December 31, 2017 , and based on the most recent analysis performed, the risk category of loans by class of loans is as follows: Pass Special Mention Substandard Nonaccrual Total One-to-four family residential real estate $ 74,437 $ — $ 255 $ 1,914 $ 76,606 One-to-four family residential real estate - non-owner occupied 21,059 — 40 109 21,208 Multi-family mortgage - Illinois 290,765 — 225 368 291,358 Multi-family mortgage - Other 297,025 — — — 297,025 Nonresidential real estate 169,817 — 154 — 169,971 Construction 1,099 — — — 1,099 Land 259 — — — 259 Commercial loans: Regional commercial banking 36,373 4,528 — — 40,901 Health care 69,480 — 2,248 — 71,728 Direct commercial lessor 39,923 — — — 39,923 Commercial leases: Investment-grade 207,460 — — — 207,460 Other 102,616 — — — 102,616 Consumer 1,597 — — — 1,597 $ 1,311,910 $ 4,528 $ 2,922 $ 2,391 $ 1,321,751 As of December 31, 2016 , and based on the most recent analysis performed, the risk category of loans by class of loans is as follows: Pass Special Mention Substandard Nonaccrual Total One-to-four family residential real estate $ 93,514 $ — $ 629 $ 2,486 $ 96,629 One-to-four family residential real estate - non-owner occupied 38,179 — 41 369 38,589 Multi-family mortgage - Illinois 297,826 122 1,048 187 299,183 Multi-family mortgage - Other 243,704 — — — 243,704 Nonresidential real estate 180,047 — 1,845 260 182,152 Construction 946 — — — 946 Land 356 — — — 356 Commercial loans: Regional commercial banking 26,365 — 66 — 26,431 Health care 41,001 — — — 41,001 Direct commercial lessor 30,881 800 — — 31,681 Commercial leases: Investment-grade 271,972 — — — 271,972 Other 84,356 161 — — 84,517 Consumer 2,255 — — — 2,255 $ 1,311,402 $ 1,083 $ 3,629 $ 3,302 $ 1,319,416
Past Due Financing Receivables	The following tables present the aging of the recorded investment in past due loans as December 31, 2016 by class of loans: 30-59 Days Past Due 60-89 Days Past Due Greater Than 89 Days Past Due Total Past Due Loans Not Past Due Total One-to-four family residential real estate $ 984 $ 335 $ 2,235 $ 3,554 $ 92,665 $ 96,219 One-to-four family residential real estate - non-owner occupied 664 114 368 1,146 37,179 38,325 Multi-family mortgage - Illinois 605 439 184 1,228 294,223 295,451 Multi-family mortgage - Other — — — — 243,944 243,944 Nonresidential real estate — — 260 260 178,644 178,904 Construction — — — — 950 950 Land — — — — 349 349 Commercial loans: Regional Commercial Banking — — — — 26,480 26,480 Health Care — — — — 41,086 41,086 Direct Commercial Lessor — — — — 31,847 31,847 Commercial leases: — Investment-grade 51 — — 51 273,405 273,456 Other — — — — 84,988 84,988 Consumer — — — — 2,263 2,263 $ 2,304 $ 888 $ 3,047 $ 6,239 $ 1,308,023 $ 1,314,262 The following tables present the aging of the recorded investment in past due loans at December 31, 2017 by class of loans: 30-59 Days Past Due 60-89 Days Past Due Greater Than 89 Days Past Due Total Past Due Loans Not Past Due Total One-to-four family residential real estate $ 86 $ 99 $ 1,801 $ 1,986 $ 74,216 $ 76,202 One-to-four family residential real estate - non-owner occupied 10 3 86 99 20,944 21,043 Multi-family mortgage - Illinois 172 — 364 536 287,171 287,707 Multi-family mortgage - Other — — — — 296,440 296,440 Nonresidential real estate 608 — — 608 166,071 166,679 Construction — — — — 1,103 1,103 Land — — — — 259 259 Commercial loans: Regional Commercial Banking — — — — 40,935 40,935 Health Care — — — — 71,738 71,738 Direct Commercial Lessor — — — — 40,237 40,237 Commercial leases: — Investment-grade 934 — — 934 207,747 208,681 Other 288 — — 288 102,873 103,161 Consumer — — — — 1,605 1,605 Total $ 2,098 $ 102 $ 2,251 $ 4,451 $ 1,311,339 $ 1,315,790
Schedule of Financing Receivables, Non Accrual Status	The following tables present the recorded investment in nonaccrual and loans past due over 90 days still on accrual by class of loans: Loan Balance Recorded Investment Loans Past Due Over 90 Days, still accruing December 31, 2017 One-to-four family residential real estate $ 3,413 $ 1,918 $ — One-to-four family residential real estate – non owner occupied 308 109 — Multi-family mortgage 376 363 — Nonresidential real estate — — — $ 4,097 $ 2,390 $ — December 31, 2016 One-to-four family residential real estate $ 2,861 $ 2,483 $ — One-to-four family residential real estate – non owner occupied 428 368 — Multi-family mortgage 187 185 — Nonresidential real estate 262 260 — $ 3,738 $ 3,296 $ —
Allowance for Credit Losses on Financing Receivables	Activity in the allowance for loan losses is as follows: For the years ended December 31, 2017 2016 2015 Beginning balance $ 8,127 $ 9,691 $ 11,990 Loans charged off: One-to-four family residential real estate (318 ) (539 ) (386 ) Multi-family mortgage (10 ) (79 ) (198 ) Nonresidential real estate (165 ) (1,718 ) (391 ) Commercial loans — — (152 ) Consumer (10 ) (25 ) (16 ) (503 ) (2,361 ) (1,143 ) Recoveries: One-to-four family residential real estate 145 321 702 Multi-family mortgage 70 162 182 Nonresidential real estate 17 200 509 Construction and land — 35 44 Commercial loans 594 309 611 Commercial leases 2 7 1 Consumer 1 2 1 829 1,036 2,050 Net recoveries (charge-off) 326 (1,325 ) 907 Recovery of loan losses (87 ) (239 ) (3,206 ) Ending balance $ 8,366 $ 8,127 $ 9,691
Loans By Class Modified As Troubled Debt Restructuring On Financing Receivables	The following tables present TDRs that occurred during the year: For the years ended December 31, 2017 2016 Number of loans Pre- Modification outstanding recorded investment Post- Modification outstanding recorded investment Number of loans Pre- Modification outstanding recorded investment Post- Modification outstanding recorded investment One-to-four family residential real estate — $ — $ — 1 $ 63 $ 63 Due to reduction in interest rate Due to extension of maturity date Due to permanent reduction in recorded investment Total For the year ended December 31, 2016 One-to-four family residential real estate $ — $ 63 $ — $ 63

Other Real Estate (Tables)

Other Real Estate (Tables)	12 Months Ended
	Dec. 31, 2017
Other Real Estate Owned [Abstract]
real estate owned, rollforward [Table Text Block]	The following represents the roll forward of OREO and the composition of OREO properties. At and For the Years Ended December 31, 2017 2016 Beginning balance $ 3,895 $ 7,011 New foreclosed properties 2,766 1,251 Valuation adjustments (333 ) (314 ) Sales (3,977 ) (4,053 ) Ending balance $ 2,351 $ 3,895
Schedule of Real Estate Properties [Table Text Block]	December 31, 2017 December 31, 2016 Balance Valuation Allowance Net OREO Balance Balance Valuation Allowance Net OREO Balance One–to–four family residential $ 836 $ (9 ) $ 827 $ 1,702 $ (137 ) $ 1,565 Multi-family mortgage — — — 370 — 370 Nonresidential real estate 1,772 (252 ) 1,520 1,171 (105 ) 1,066 Land 48 (44 ) 4 1,101 (207 ) 894 $ 2,656 $ (305 ) $ 2,351 $ 4,344 $ (449 ) $ 3,895
other real estate owned valuation allowance rollforward [Table Text Block]	Activity in the valuation allowance is as follows: At and For the Years Ended December 31, 2017 2016 Beginning of year $ 449 $ 1,042 Additions charged to expense 333 314 Reductions from sales of other real estate owned (477 ) (907 ) End of year $ 305 $ 449

Premises and Equipment (Tables)

Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant, Equipment And Leases [Abstract]
Property, Plant and Equipment	Year-end premises and equipment are as follows: December 31, 2017 2016 Land and land improvements $ 12,265 $ 13,820 Buildings and improvements 29,556 37,416 Furniture and equipment 9,678 9,660 Computer equipment 3,983 4,058 55,482 64,954 Accumulated depreciation (30,626 ) (33,541 ) $ 24,856 $ 31,413
Schedule of Future Minimum Rental Payments and Receipts for Operating Leases	The projected minimum rental expense under existing leases, not including taxes, insurance, and maintenance, as of December 31, 2017 is as follows: 2018 $ 497 2019 471 2020 459 2021 464 2022 491 Thereafter 3,753 $ 6,135 The Company has subleased some of its branch facilities and currently is entitled to receive income as follows: 2018 $ 2 2019 2 2020 2 2021 1 2022 1 $ 8

Core Deposit Intangible (Tables

Core Deposit Intangible (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets	The following table presents the changes in the carrying amount of core deposit intangible, gross carrying amount, accumulated amortization, and net book value: December 31, 2017 2016 Balance at the beginning of the year $ 782 $ 1,305 Amortization (496 ) (523 ) Additions — — Net Carrying Value $ 286 $ 782 Gross carrying amount $ 5,932 $ 5,932 Accumulated amortization (5,646 ) (5,150 ) Net Carrying Value $ 286 $ 782
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	Estimated amortization expense for each of the next five years is as follows: 2018 $ 184 2019 61 2020 34 2021 7 2022 —

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2017
Deposits [Abstract]
Schedule Of Deposits By Type	Composition of deposits is as follows: December 31, 2017 2016 Noninterest-bearing demand deposits $ 234,354 $ 249,539 Interest-bearing NOW accounts 289,657 267,054 Money market accounts 299,581 311,183 Savings deposits 160,501 160,002 Certificates of deposit 355,958 351,612 $ 1,340,051 $ 1,339,390
Schedule Of Maturities For Total Time Deposits	Scheduled maturities of certificates of deposit for the next five years are as follows: 2018 $ 258,567 2019 68,756 2020 16,421 2021 8,697 2022 3,517

Borrowings (Tables)

Borrowings (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	ear-end, advances from the FHLB were as follows: December 31, 2017 2016 Contractual Rate Amount Contractual Rate Amount Fixed-rate advance from FHLB, due within 1 year 1.34 % $ 60,000 0.67 % $ 50,000

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of Income Tax Expense (Benefit)	The income tax expense is as follows: For the years ended December 31, 2017 2016 2015 Current expense (benefit) $ (2,658 ) $ 308 $ 346 Deferred expense 7,361 4,390 5,079 Expense due to enactment of federal tax reform 2,487 — — Total income tax expense $ 7,190 $ 4,698 $ 5,425
Schedule of Effective Income Tax Rate	A reconciliation of the provision for income taxes computed at the statutory federal corporate tax rate of 34% for 2017 , 2016 and 2015 to the income tax expense in the consolidated statements of operations follows: For the years ended December 31, 2017 2016 2015 Expense computed at the statutory federal tax rate $ 5,506 $ 4,148 $ 4,794 State taxes and other, net (204 ) 464 626 Bank owned life insurance (90 ) (70 ) (66 ) ESOP/Share based compensation (509 ) 156 71 Expense due to enactment of federal tax reform 2,487 — — $ 7,190 $ 4,698 $ 5,425 Effective income tax rate 44.77 % 38.51 % 38.48 %
Schedule of Deferred Assets And Liabilities	The net deferred tax asset is as follows: December 31, 2017 2016 Gross Deferred tax assets Allowance for loan losses $ 2,258 $ 3,117 Alternative minimum tax, general business credit and net operating loss carryforwards 11,864 20,857 Tax deductible goodwill and core deposit intangible 801 1,466 Other 1,395 2,540 16,318 27,980 Gross Deferred tax liabilities Net deferred loan origination costs (1,255 ) (1,874 ) Purchase accounting adjustments (1,744 ) (2,644 ) Other (619 ) (817 ) Unrealized gain on securities (137 ) (234 ) (3,755 ) (5,569 ) $ 12,563 $ 22,411
Schedule of Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: December 31, 2017 2016 Beginning of year $ 57 $ 108 Additions based on tax positions related to the current year 60 — Additions for tax positions of prior years 12 — Reductions due to the statute of limitations and reductions for tax positions of prior years — (51 ) End of year $ 129 $ 57

Regulatory Matters (Tables)

Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2017
Banking and Thrift [Abstract]
Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations	Actual and required capital amounts and ratios were: Actual Required for Capital Adequacy Purposes To be Well-Capitalized under Prompt Corrective Action Provisions Amount Ratio Amount Ratio Amount Ratio December 31, 2017 Total capital (to risk-weighted assets): Consolidated $ 195,371 17.06 % $ 91,590 8.00 % N/A N/A BankFinancial, NA 188,582 16.48 91,572 8.00 $ 114,466 10.00 % Tier 1 (core) capital (to risk-weighted assets): Consolidated 187,005 16.33 68,692 6.00 N/A N/A BankFinancial, NA 180,216 15.74 68,679 6.00 91,572 8.00 Common Tier 1 (CET1) Consolidated 187,005 16.33 51,519 4.50 N/A N/A BankFinancial, NA 180,216 15.74 51,509 4.50 74,403 6.50 Tier 1 (core) capital (to adjusted average total assets): Consolidated 187,005 11.49 65,085 4.00 N/A N/A BankFinancial, NA 180,216 11.08 65,045 4.00 81,307 5.00 December 31, 2016 Total capital (to risk-weighted assets): Consolidated $ 193,845 16.96 % $ 91,414 8.00 % N/A N/A BankFinancial, NA 168,113 14.72 91,386 8.00 $ 114,232 10.00 % Tier 1 (core) capital (to risk-weighted assets): Consolidated 185,718 16.25 68,560 6.00 N/A N/A BankFinancial, NA 159,986 14.01 68,539 6.00 91,386 8.00 Common Tier 1 (CET1) Consolidated 185,718 16.25 51,420 4.50 N/A N/A BankFinancial, NA 159,986 14.01 51,404 4.50 74,251 6.50 Tier 1 (core) capital (to adjusted average total assets): Consolidated 185,718 11.92 62,306 4.00 N/A N/A BankFinancial, NA 159,986 10.27 62,303 4.00 77,879 5.00

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Compensation and Retirement Disclosure [Abstract]
Schedule of Employee Stock Ownership Plan (ESOP) Disclosures	Shares held by the ESOP were as follows: December 31, 2017 2016 Allocated to participants 1,203,810 1,125,448 Distributed to participants (317,914 ) (313,223 ) Unearned — 831,852 Total ESOP shares 885,896 1,644,077 Fair value of unearned shares $ — $ 12,328

Equity Incentive Plans (Tables)

Equity Incentive Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Stock Option Activity	A summary of the activity in the stock option plan for 2017 follows: Stock Options Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (1) Stock options outstanding at January 1, 2016 1,752,156 $ 12.30 1.48 $ 778 Stock options granted — — Stock options exercised — — Stock options outstanding at December 31, 2016 1,752,156 $ 12.30 0.48 $ 4,422 Stock options granted — — Stock options exercised (1,752,156 ) 12.30 Stock options outstanding at December 31, 2017 — $ — 0.00 $ — (1) Stock option aggregate intrinsic value represents the number of shares subject to options multiplied by the difference (if positive) in the closing market price of the common stock underlying the options on the date shown and the weighted average exercise price.
Schedule of Unvested Shares of Restricted Stock	Restricted Stock Number of Shares (1) Weighted Average Fair Value at Grant Date Weighted Average Term to Vest (in years) Aggregate Intrinsic Value (2) Shares outstanding at January 1, 2016 7,934 $ 8.14 0.31 $ 100 Shares granted — — Shares vested (6,994 ) — Shares forfeited — — Shares outstanding at December 31, 2016 940 $ 8.14 0.74 $ 14 Shares granted — — Shares vested — — Shares forfeited — — Shares outstanding at December 31, 2017 940 $ 8.14 0.00 $ 14 (1) The end of period balances consist only of unvested shares. (2) Restricted stock aggregate intrinsic value represents the number of shares of restricted stock multiplied by the market price of the common stock underlying the outstanding shares on the date shown.

Loan Commitments and Other Of40

Loan Commitments and Other Off-Balance Sheet Activities (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of Off-balance Sheet Instruments Outstanding	The contractual or notional amounts are as follows: December 31, 2017 2016 Financial instruments wherein contractual amounts represent credit risk Commitments to extend credit $ 46,615 $ 91,172 Standby letters of credit 6,757 1,305 Unused lines of credit 129,207 125,332 Commitments to sell mortgages — —

Fair Value (Tables)

Fair Value (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Schedule of Company's financial instruments measured at fair values	The following table sets forth the Company’s financial assets that were accounted for at fair value and are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. Fair Value Measurements Using Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fair Value December 31, 2017 Securities: Certificates of deposit $ — $ 75,916 $ — $ 75,916 Equity mutual fund 499 — — 499 Mortgage-backed securities – residential — 12,472 — 12,472 Collateralized mortgage obligations – residential — 4,486 — 4,486 SBA-guaranteed loan participation certificates — 10 — 10 $ 499 $ 92,884 $ — $ 93,383 December 31, 2016 Securities: Certificates of deposit $ — $ 85,938 $ — $ 85,938 Equity mutual fund 499 — — 499 Mortgage-backed securities - residential — 15,184 — 15,184 Collateralized mortgage obligations – residential — 5,574 — 5,574 SBA-guaranteed loan participation certificates — 17 — 17 $ 499 $ 106,713 $ — $ 107,212
Schedule of Company's financial instruments measured on non recurring at fair values	The following table sets forth the Company’s assets that were measured at fair value on a non-recurring basis: Fair Value Measurement Using Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fair Value December 31, 2017 Other real estate owned: One–to–four family residential real estate $ — $ — $ 102 $ 102 Nonresidential real estate — — 814 814 Other real estate owned $ — $ — $ 916 $ 916 December 31, 2016 Impaired loans: Nonresidential real estate $ — $ — $ 234 $ 234 Impaired loans $ — $ — $ 234 $ 234 Other real estate owned: One–to–four family residential real estate $ — $ — $ 1,282 $ 1,282 Nonresidential real estate — — 553 553 Land — — 47 47 Other real estate owned $ — $ — $ 1,882 $ 1,882
Schedule of fair value quantitative information	The following table presents quantitative information, based on certain empirical data with respect to Level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis at December 31, 2017 : Fair Value Valuation Technique Unobservable Input Range (Weighted Average) Other real estate owned One-to-four family residential real estate $ 102 Sales comparison Discount applied to valuation 5.6% Nonresidential real estate 814 Sales comparison Comparison between sales and income approaches -3.66% to 15.22% (11.0%) $ 916
Carrying amount and estimated fair value of financial instruments	The carrying amount and estimated fair value of financial instruments is as follows: Fair Value Measurements at December 31, 2017 Using: Carrying Amount Level 1 Level 2 Level 3 Total Financial assets Cash and cash equivalents $ 127,592 $ 13,572 $ 114,020 $ — $ 127,592 Securities 93,383 499 92,884 — 93,383 Loans receivable, net of allowance for loan losses 1,314,651 — 1,323,139 — 1,323,139 FHLB and FRB stock 8,290 — — — N/A Accrued interest receivable 4,619 — 4,619 — 4,619 Financial liabilities Noninterest-bearing demand deposits $ 234,354 $ — $ 234,354 $ — $ 234,354 NOW and money market accounts 589,238 589,238 589,238 Savings deposits 160,501 — 160,501 — 160,501 Certificates of deposit 355,958 — 353,969 — 353,969 Borrowings 60,768 — 60,627 — 60,627 Accrued interest payable 147 — 147 — 147 Fair Value Measurements at December 31, 2016 Using: Carrying Amount Level 1 Level 2 Level 3 Total Financial assets Cash and cash equivalents $ 96,684 $ 13,053 $ 83,631 $ — $ 96,684 Securities 107,212 499 106,713 — 107,212 Loans receivable, net of allowance for loan losses 1,312,952 — 1,322,713 234 1,322,947 FHLB and FRB stock 11,650 — — — N/A Accrued interest receivable 4,381 — 4,381 — 4,381 Financial liabilities Noninterest-bearing demand deposits $ 249,539 $ — $ 249,539 $ — $ 249,539 NOW and money market accounts 578,237 578,237 578,237 Savings deposits 160,002 — 160,002 — 160,002 Certificates of deposit 351,612 — 350,593 — 350,593 Borrowings 51,069 — 50,015 — 50,015 Accrued interest payable 102 — 102 — 102

Company Only Condensed Financ42

Company Only Condensed Financial Information (Tables)	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Statements of Financial Condition	Condensed Statements of Financial Condition December 31, 2017 2016 Assets Cash in subsidiary $ 6,393 $ 14,543 Loan receivable from ESOP — 10,767 Investment in subsidiary 188,873 176,756 Deferred tax asset 2,076 2,367 Other assets 3,307 347 $ 200,649 $ 204,780 Liabilities and Stockholders' Equity Accrued expenses and other liabilities $ 3,015 $ — Total stockholders’ equity 197,634 204,780 $ 200,649 $ 204,780
Condensed Statements of Operations	Condensed Statements of Operations For the years ended December 31, 2017 2016 2015 Interest income $ 110 $ 503 $ 544 Dividends from subsidiary 10,629 16,888 19,710 Other expense 1,693 1,846 1,536 Income before income tax and undistributed subsidiary income 9,046 15,545 18,718 Income tax expense (benefit) 290 (502 ) (783 ) Income before equity in undistributed subsidiary income 8,756 16,047 19,501 Equity in undistributed subsidiary income (excess distributions) 248 (8,545 ) (10,826 ) Net income $ 9,004 $ 7,502 $ 8,675
Condensed Statements of Cash Flows	Condensed Statements of Cash Flows For the years ended December 31, 2017 2016 2015 Cash flows from operating activities Net income $ 9,004 $ 7,502 $ 8,675 Adjustments: Equity in undistributed subsidiary excess distributions (248 ) 8,545 10,826 Change in other assets (2,712 ) (497 ) (793 ) Change in accrued expenses and other liabilities 3,015 — — Net cash from operating activities 9,059 15,550 18,708 Cash flows from investing activities Principal payments received on ESOP loan — 1,032 992 Net cash from investing activities — 1,032 992 Cash flows from financing activities Net exercise of stock options (1,237 ) — — Repurchase and retirement of common stock (10,819 ) (13,215 ) (9,970 ) Cash dividends paid on common stock (5,153 ) (4,133 ) (4,145 ) Net cash used in financing activities (17,209 ) (17,348 ) (14,115 ) Net change in cash in subsidiary (8,150 ) (766 ) 5,585 Beginning cash in subsidiary 14,543 15,309 9,724 Ending cash in subsidiary $ 6,393 $ 14,543 $ 15,309

Selected Quarterly Financial 43

Selected Quarterly Financial Data (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data	For the year ended December 31, 2017 First Quarter Second Quarter Third Quarter Fourth Quarter Interest income $ 13,362 $ 13,649 $ 14,121 $ 15,047 Interest expense 1,276 1,456 1,615 1,742 Net interest income 12,086 12,193 12,506 13,305 Provision for (recovery of) loan losses 161 49 (225 ) (72 ) Net interest income 11,925 12,144 12,731 13,377 Noninterest income 1,544 1,607 1,623 1,634 Noninterest expense 11,266 9,607 10,200 9,318 Income before income taxes 2,203 4,144 4,154 5,693 Income tax expense 322 1,572 594 4,702 Net income $ 1,881 $ 2,572 $ 3,560 $ 991 Basic earnings per common share $ 0.10 $ 0.14 $ 0.20 $ 0.06 Diluted earnings per common share 0.10 0.14 0.20 0.06	For the year ended December 31, 2016 First Second Third Fourth Interest income $ 12,759 $ 12,581 $ 12,845 $ 12,743 Interest expense 856 952 1,014 1,148 Net interest income 11,903 11,629 11,831 11,595 Provision for (recovery of) loan losses (490 ) 1,315 (525 ) (539 ) Net interest income 12,393 10,314 12,356 12,134 Noninterest income 1,594 1,537 1,637 1,777 Noninterest expense 10,930 10,506 9,912 10,194 Income before income taxes 3,057 1,345 4,081 3,717 Income tax expense 1,153 514 1,573 1,458 Net income $ 1,904 $ 831 $ 2,508 $ 2,259 Basic earnings per common share $ 0.10 $ 0.04 $ 0.13 $ 0.12 Diluted earnings per common share 0.10 0.04 0.13 0.12

Summary of Significant Accoun44

Summary of Significant Accounting Policies - Mortgage Servicing Rights (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Principal Amount Outstanding of Loans Held-in-portfolio	$ 90,700,000	$ 106,400,000
Escrow deposit	2,600,000	2,700,000
Fair value of mortgage servicing rights	513,000	$ 612,000
Valuation Allowance for Impairment of Recognized Servicing Assets, Balance	$ 0

Summary of Significant Accoun45

Summary of Significant Accounting Policies - Premises and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Available-for-sale Securities	$ 93,383	$ 107,212
Transfer of Property to Held-for-sale	5,667	0	$ 0
Premises held-for-sale	$ 5,667	$ 0
Building and building improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Premises and Equipment, Useful life	25 years
Building and building improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Premises and Equipment, Useful life	40 years
Building Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Premises and Equipment, Useful life	10 years
Building Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Premises and Equipment, Useful life	20 years
Furniture and equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Premises and Equipment, Useful life	5 years
Furniture and equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Premises and Equipment, Useful life	15 years
Computer Equipment And Software [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Premises and Equipment, Useful life	2 years
Computer Equipment And Software [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Premises and Equipment, Useful life	5 years
Automobiles [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Premises and Equipment, Useful life	4 years

Summary of Significant Accoun46

Summary of Significant Accounting Policies - Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Deferred Tax Assets, Net	$ 12,563				$ 22,411				$ 12,563	$ 22,411
Total income tax expense (benefit)	4,702	$ 594	$ 1,572	$ 322	1,458	$ 1,573	$ 514	$ 1,153	7,190	4,698	$ 5,425
Unrecognized tax benefits	$ 129				$ 57				$ 129	$ 57	$ 108

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings (Loss) Per Share, Basic and Diluted [Abstract]
Net income (loss) available to common stockholders	$ 991	$ 3,560	$ 2,572	$ 1,881	$ 2,259	$ 2,508	$ 831	$ 1,904	$ 9,004	$ 7,502	$ 8,675
Average common shares outstanding (shares)									18,429,018	19,673,416	20,708,775
Less:
Unearned ESOP shares (shares)									(148,179)	(682,362)	(780,227)
Unvested restricted stock shares (shares)									(940)	(3,103)	(10,545)
Weighted average common shares outstanding (shares)									18,279,899	18,987,951	19,918,003
Add - Net effect of dilutive stock options and unvested restricted stock									437	59,188	3,516
Weighted average diluted common shares outstanding (shares)									18,280,336	19,047,139	19,921,519
Basic earnings (loss) per common share (usd per share)	$ 0.06	$ 0.20	$ 0.14	$ 0.10		$ 0.13	$ 0.04	$ 0.10	$ 0.49	$ 0.40	$ 0.44
Diluted earnings (loss) per common share (usd per share)		$ 0.20	$ 0.14	$ 0.10	$ 0.12	$ 0.13	$ 0.04	$ 0.10	$ 0.49	$ 0.39	$ 0.44
Number of antidilutive stock options excluded from the diluted earnings per share calculation									0	536,459	536,459
Weighted average exercise price of anti-dilutive option shares									$ 0	$ 12.99	$ 12.99

Securities - Fair Value of Secu

Securities - Fair Value of Securites (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Unrealized gains and losses recognized in accumulated other comprehensive income (loss)
Amortized Cost	$ 92,876,000	$ 106,603,000
Available-for-sale Securities, Gross Unrealized Gain	536,000	659,000
Available-for-sale Securities, Gross Unrealized Losses	(29,000)	(50,000)
Available-for-sale Securities	93,383,000	107,212,000
Certificates of deposit [Member]
Unrealized gains and losses recognized in accumulated other comprehensive income (loss)
Amortized Cost	75,916,000	85,938,000
Available-for-sale Securities, Gross Unrealized Gain	0	0
Available-for-sale Securities, Gross Unrealized Losses	0	0
Available-for-sale Securities	75,916,000	85,938,000
Equity mutual fund [Member]
Unrealized gains and losses recognized in accumulated other comprehensive income (loss)
Amortized Cost	500,000	500,000
Available-for-sale Securities, Gross Unrealized Gain	0	0
Available-for-sale Securities, Gross Unrealized Losses	(1,000)	(1,000)
Available-for-sale Securities	499,000	499,000
Mortgage - backed securities - residential [Member]
Unrealized gains and losses recognized in accumulated other comprehensive income (loss)
Amortized Cost	11,969,000	14,561,000
Available-for-sale Securities, Gross Unrealized Gain	520,000	644,000
Available-for-sale Securities, Gross Unrealized Losses	(17,000)	(21,000)
Available-for-sale Securities	12,472,000	15,184,000
Collateralized mortgage obligations - residential [Member]
Unrealized gains and losses recognized in accumulated other comprehensive income (loss)
Amortized Cost	4,481,000	5,587,000
Available-for-sale Securities, Gross Unrealized Gain	16,000	15,000
Available-for-sale Securities, Gross Unrealized Losses	(11,000)	(28,000)
Available-for-sale Securities	4,486,000	5,574,000
SBA-guaranteed loan participation certificates [Member]
Unrealized gains and losses recognized in accumulated other comprehensive income (loss)
Amortized Cost	10,000	17,000
Available-for-sale Securities, Gross Unrealized Gain	0	0
Available-for-sale Securities, Gross Unrealized Losses	0	0
Available-for-sale Securities	$ 10,000	$ 17,000

Securities - Amortized Cost and

Securities - Amortized Cost and Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities Pledged as Collateral	$ 3,700	$ 4,700
Amortized cost and fair values of securities
Total amortized cost	92,876	106,603
Available-for-sale Securities	93,383	107,212
Available-for-sale Debt Securities, Amortized Cost Basis	92,376
Available-for-sale Securities, Debt Securities	92,884
Certificates of Deposit [Member]
Amortized cost and fair values of securities
Total amortized cost	75,916	85,938
Available-for-sale Securities	75,916	85,938
Mortgage - backed securities - residential [Member]
Amortized cost and fair values of securities
Total amortized cost	11,969	14,561
Available-for-sale Securities	12,472	15,184
Collateralized mortgage obligations - residential [Member]
Amortized cost and fair values of securities
Total amortized cost	4,481	5,587
Available-for-sale Securities	4,486	5,574
SBA-guaranteed loan participation certificates [Member]
Amortized cost and fair values of securities
Total amortized cost	10	17
Available-for-sale Securities	$ 10	$ 17

Securities - Proceeds and Gross

Securities - Proceeds and Gross Gains (Losses) From Sale of Securities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Proceeds	$ 0	$ 46	$ 0
Gross gains	0	46	0
Gross losses	$ 0	$ 0	$ 0

Securities - Unrealized Losses

Securities - Unrealized Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Amortized cost and fair values of securities
Less than 12 Months, Fair Value	$ 499	$ 5,377
12 Months or More, Fair Value	3,232	1,028
Fair Value, Total	3,731	6,405
Unrealized loss of securities
Less than 12 Months, Unrealized Loss	(1)	(40)
12 Months or More, Unrealized Loss	(28)	(10)
Unrealized Loss, Total	(29)	(50)
Equity Funds [Member]
Amortized cost and fair values of securities
Less than 12 Months, Fair Value	499	499
12 Months or More, Fair Value	0	0
Fair Value, Total	499	499
Unrealized loss of securities
Less than 12 Months, Unrealized Loss	(1)
12 Months or More, Unrealized Loss	0	0
Unrealized Loss, Total	(1)	(1)
Residential Mortgage Backed Securities [Member]
Amortized cost and fair values of securities
Less than 12 Months, Fair Value	0	1,187
12 Months or More, Fair Value	1,149	0
Fair Value, Total	1,149	1,187
Unrealized loss of securities
Less than 12 Months, Unrealized Loss	0	(21)
12 Months or More, Unrealized Loss	(17)	0
Unrealized Loss, Total	(17)	(21)
Collateralized mortgage obligations - residential [Member]
Amortized cost and fair values of securities
Less than 12 Months, Fair Value	0	3,691
12 Months or More, Fair Value	2,083	1,028
Fair Value, Total	2,083	4,719
Unrealized loss of securities
Less than 12 Months, Unrealized Loss	0	(18)
12 Months or More, Unrealized Loss	(11)	(10)
Unrealized Loss, Total	$ (11)	$ (28)

Loans Receivable (Details)

Loans Receivable (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Loans receivable
Total loans	$ 1,321,751,000	$ 1,319,416,000
Net deferred loan origination costs	1,266,000	1,663,000
Allowance for loan losses	(8,366,000)	(8,127,000)	$ (9,691,000)	$ (11,990,000)
Loans, net	1,314,651,000	1,312,952,000
One-to-four family residential real estate loans [Member]
Loans receivable
Total loans	97,814,000	135,218,000
Allowance for loan losses	(850,000)	(1,168,000)
Multi-family mortgage loans [Member]
Loans receivable
Total loans	588,383,000	542,887,000
Allowance for loan losses	(3,849,000)	(3,647,000)
Nonresidential Real Estate [Member]
Loans receivable
Total loans	169,971,000	182,152,000
Allowance for loan losses	(1,605,000)	(1,794,000)
Construction and land loans [Member]
Loans receivable
Total loans	1,358,000	1,302,000
Allowance for loan losses	(32,000)	(32,000)
Commercial loans [Member]
Loans receivable
Total loans	152,552,000	99,088,000
Allowance for loan losses	(1,357,000)	(733,000)
Commercial leases [Member]
Loans receivable
Total loans	310,076,000	356,514,000
Allowance for loan losses	(655,000)	(714,000)
Consumer loans [Member]
Loans receivable
Total loans	1,597,000	2,255,000
Allowance for loan losses	(18,000)	(39,000)
Nonresidential real estate loans [Member]
Loans receivable
Total loans	$ 169,971,000	$ 182,152,000
No Public Rating [Member] | Maximum [Member] | Commercial leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial Leases, Maturity	5 years
Collateralized Loan [Member] | Multi-family mortgage loans [Member]
Loans receivable
Collateralized Loan Receivable, Percentage Of Collateral Located Outside Primary Market Area	46.50%
Collateralized Loan [Member] | Nonresidential real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Projected Cash Flow To Loan Debt Service Requirement	120.00%
Collateralized Loan [Member] | Maximum [Member] | Multi-family mortgage loans [Member]
Loans receivable
Total loans	$ 5,000,000
Collateralized Loan [Member] | Maximum [Member] | Nonresidential real estate loans [Member]
Loans receivable
Total loans	5,000,000
Collateralized Loan [Member] | Minimum [Member] | Multi-family mortgage loans [Member]
Loans receivable
Total loans	500,000
Collateralized Loan [Member] | Minimum [Member] | Nonresidential real estate loans [Member]
Loans receivable
Total loans	$ 250,000
Mortgage loans above $400,000 [Member] | Collateralized Loan [Member] | Multi-family mortgage loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Projected Cash Flow To Loan Debt Service Requirement	120.00%
Conforming Loans [Member] | $2,500,000 [Member] | Maximum [Member] | Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Mortgage Loans on Real Estate, Face Amount of Mortgages	$ 424,000
Adjustable Rate And Fixed Rate Residential Mortgage [Member] | $2,500,000 [Member] | Maximum [Member] | Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Mortgage Loans on Real Estate, Face Amount of Mortgages	$ 2,500,000
First Mortgage [Member] | Residential Mortgage [Member]
Loans receivable
Percent Threshold On Loan To Value Ratios Requiring Private Mortgage Insurance	80.00%

Loans Receivable - Loan Origina

Loans Receivable - Loan Origination and Risk Management (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, amount	$ 1,321,751,000	$ 1,319,416,000
Maximum [Member] | Finance Leases Financing Receivable [Member] | Investment Grade [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding credit exposure	15,000,000
Multi-family mortgage loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, amount	$ 588,383,000	542,887,000
Multi-family mortgage loans [Member] | Collateralized Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collateralized Loan Receivable, Percentage Of Collateral Located Outside Primary Market Area	46.50%
Multi-family mortgage loans [Member] | Collateralized Loan [Member] | Mortgage loans above $400,000 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Projected Cash Flow To Loan Debt Service Requirement	120.00%
Multi-family mortgage loans [Member] | Minimum [Member] | Collateralized Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, amount	$ 500,000
Multi-family mortgage loans [Member] | Maximum [Member] | Collateralized Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, amount	$ 5,000,000
Loan amount as a percentage to value of property collateralized	0.8
Nonresidential real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, amount	$ 169,971,000	182,152,000
Nonresidential real estate loans [Member] | Collateralized Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Projected Cash Flow To Loan Debt Service Requirement	120.00%
Nonresidential real estate loans [Member] | Collateralized Loan [Member] | Fixed Rate Nonresidential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortization period	15 years
Nonresidential real estate loans [Member] | Minimum [Member] | Collateralized Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, amount	$ 250,000
Maturity period	3 years
Balloon maturity	3 years
Amortization period	20 years
Nonresidential real estate loans [Member] | Maximum [Member] | Collateralized Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, amount	$ 5,000,000
Loan amount as a percentage to value of property collateralized	0.8
Maturity period	5 years
Balloon maturity	5 years
Amortization period	30 years
Residential mortgage [Member] | Maximum [Member] | Adjustable Rate And Fixed Rate Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Maturity period	30 years
Residential mortgage [Member] | Maximum [Member] | $2,500,000 [Member] | Adjustable Rate And Fixed Rate Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Mortgage Loans on Real Estate, Face Amount of Mortgages	$ 2,500,000
Residential mortgage [Member] | Maximum [Member] | $2,500,000 [Member] | Conforming Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Mortgage Loans on Real Estate, Face Amount of Mortgages	424,000
Finance Leases Financing Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, amount	$ 310,076,000	$ 356,514,000
Finance Leases Financing Receivable [Member] | Minimum [Member] | Internal Credit Assessment [Domain]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of borrowers with credit rating	50.00%
Finance Leases Financing Receivable [Member] | Maximum [Member] | No Public Rating [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial Leases, Maturity	5 years
Outstanding credit exposure	$ 10,000,000
Finance Leases Financing Receivable [Member] | Maximum [Member] | Investment Grade [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding credit exposure	$ 10,000,000

Loans Receivable - Allowance fo

Loans Receivable - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for loan losses and the loans receivable by portfolio segment
Individually evaluated for impairment	$ 0	$ 26
Collectively evaluated for impairment	8,366	8,101
Allowance for loan losses	8,366	8,127	$ 9,691	$ 11,990
Individually evaluated for impairment	5,214	6,009
Collectively evaluated for impairment	1,316,537	1,313,407
Total loans	1,321,751	1,319,416
Net deferred loan origination costs	1,266	1,663
Loans, net	1,314,651	1,312,952
One-to-four family residential real estate loans [Member]
Allowance for loan losses and the loans receivable by portfolio segment
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	850	1,168
Allowance for loan losses	850	1,168
Individually evaluated for impairment	4,265	4,962
Collectively evaluated for impairment	93,549	130,256
Total loans	97,814	135,218
Multi-family mortgage loans [Member]
Allowance for loan losses and the loans receivable by portfolio segment
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	3,849	3,647
Allowance for loan losses	3,849	3,647
Individually evaluated for impairment	949	787
Collectively evaluated for impairment	587,434	542,100
Total loans	588,383	542,887
Nonresidential Real Estate [Member]
Allowance for loan losses and the loans receivable by portfolio segment
Individually evaluated for impairment	0	26
Collectively evaluated for impairment	1,605	1,768
Allowance for loan losses	1,605	1,794
Individually evaluated for impairment	0	260
Collectively evaluated for impairment	169,971	181,892
Total loans	169,971	182,152
Construction and land loans [Member]
Allowance for loan losses and the loans receivable by portfolio segment
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	32	32
Allowance for loan losses	32	32
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	1,358	1,302
Total loans	1,358	1,302
Commercial loans [Member]
Allowance for loan losses and the loans receivable by portfolio segment
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	1,357	733
Allowance for loan losses	1,357	733
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	152,552	99,088
Total loans	152,552	99,088
Commercial leases [Member]
Allowance for loan losses and the loans receivable by portfolio segment
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	655	714
Allowance for loan losses	655	714
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	310,076	356,514
Total loans	310,076	356,514
Consumer loans [Member]
Allowance for loan losses and the loans receivable by portfolio segment
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	18	39
Allowance for loan losses	18	39
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	1,597	2,255
Total loans	$ 1,597	$ 2,255

Loans Receivable - Activity in

Loans Receivable - Activity in the Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				$ 8,127				$ 9,691	$ 8,127	$ 9,691	$ 11,990
Loans charged off									(503)	(2,361)	(1,143)
Recoveries									829	1,036	2,050
Net charge-off									(326)	1,325	(907)
Provision for (recovery of) loan losses	$ (72)	$ (225)	$ 49	161	$ (539)	$ (525)	$ 1,315	$ (490)	(87)	(239)	(3,206)
Ending balance	8,366				8,127				8,366	8,127	9,691
One-to-four family residential real estate loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				1,168					1,168
Loans charged off									(318)	(539)	(386)
Recoveries									145	321	702
Ending balance	850				1,168				850	1,168
Multi-family mortgage loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				3,647					3,647
Loans charged off									(10)	(79)	(198)
Recoveries									70	162	182
Ending balance	3,849				3,647				3,849	3,647
Nonresidential real estate loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Loans charged off									(165)	(1,718)	(391)
Recoveries									17	200	509
Construction and land loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				32					32
Recoveries									0	35	44
Ending balance	32				32				32	32
Commercial loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				733					733
Loans charged off									0	0	(152)
Recoveries									594	309	611
Ending balance	1,357				733				1,357	733
Commercial leases [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				714					714
Recoveries									2	7	1
Ending balance	655				714				655	714
Consumer loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				$ 39					39
Loans charged off									(10)	(25)	(16)
Recoveries									1	2	$ 1
Ending balance	$ 18				$ 39				$ 18	$ 39

Loans Receivable - Loans Indivi

Loans Receivable - Loans Individually Evaluated for Impairment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Loans individually evaluated for impairment by class loans
Loan Balance		$ 6,669
Recorded Investment		5,721
Partial Charge-off		1,005
Average Investment in Impaired Loans		4,178
Interest Income Recognized		120
Allowance for loan losses (With an allowance recorded)	$ 0	26
Impaired Loan, Total	6,007	6,931
Recorded Investment, Total	5,196	5,981
Partial Charge-offs, Total	806	1,026
Average Investment in Impaired Loans, Total	5,059	4,342
Interest Income Recognized, Total	238	120
One-to-four family residential real estate loans [Member]
Loans individually evaluated for impairment by class loans
Loan Balance	5,049	5,379
Recorded Investment	4,248	4,548
Partial Charge-off	806	886
Average Investment in Impaired Loans	4,212	2,947
Interest Income Recognized	197	70
Allowance for loan losses (With an allowance recorded)	0	0
One-to-four family residential real estate loans - non-owner occupied loans [Member]
Loans individually evaluated for impairment by class loans
Loan Balance		503
Recorded Investment		386
Partial Charge-off		119
Average Investment in Impaired Loans		251
Interest Income Recognized		9
Multi-family mortgage loans [Member]
Loans individually evaluated for impairment by class loans
Loan Balance	958	787
Recorded Investment	948	787
Partial Charge-off	0	0
Average Investment in Impaired Loans	847	980
Interest Income Recognized	41	41
Allowance for loan losses (With an allowance recorded)	0	0
Nonresidential real estate loans [Member]
Loans individually evaluated for impairment by class loans
Loan Balance (With an allowance recorded)		262
Recorded Investment (With an allowance recorded)		260
Partial Charge-offs (With an allowance recorded)		21
Allowance for loan losses (With an allowance recorded)		26
Average Investment in Impaired Loans (With an allowance recorded)		164
Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method		0
Consumer loans [Member]
Loans individually evaluated for impairment by class loans
Allowance for loan losses (With an allowance recorded)	$ 0	$ 0

Loans Receivable - Nonaccrual L

Loans Receivable - Nonaccrual Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Unpaid Principal Balance	$ 4,097	$ 3,738
Recorded Investment	2,390	3,296
Loans Past Due Over 90 Days, still accruing	0	0
One-to-four family residential real estate loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Unpaid Principal Balance	3,413	2,861
Recorded Investment	1,918	2,483
Loans Past Due Over 90 Days, still accruing	0	0
One-to-four family residential real estate loans - non-owner occupied loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Unpaid Principal Balance	308	428
Recorded Investment	109	368
Loans Past Due Over 90 Days, still accruing	0	0
Multi-family mortgage loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Unpaid Principal Balance	376	187
Recorded Investment	363	185
Loans Past Due Over 90 Days, still accruing	0	0
Nonresidential real estate loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Unpaid Principal Balance	0	262
Recorded Investment	0	260
Loans Past Due Over 90 Days, still accruing	$ 0	$ 0

Loans Receivable - Past Due Loa

Loans Receivable - Past Due Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	$ 4,451	$ 6,239
Recorded investment, loans not past due	1,311,339	1,308,023
Recorded investment, total	1,315,790	1,314,262
One-to-four family residential real estate loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	1,986	3,554
Recorded investment, loans not past due	74,216	92,665
Recorded investment, total	76,202	96,219
One-to-four family residential real estate loans - non-owner occupied loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	99	1,146
Recorded investment, loans not past due	20,944	37,179
Recorded investment, total	21,043	38,325
Multi-family mortgage loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	536	1,228
Recorded investment, loans not past due	287,171	294,223
Recorded investment, total	287,707	295,451
Wholesale commercial lending [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
Recorded investment, loans not past due	296,440	243,944
Recorded investment, total	296,440	243,944
Nonresidential real estate loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	608	260
Recorded investment, loans not past due	166,071	178,644
Recorded investment, total	166,679	178,904
Construction loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due		0
Recorded investment, loans not past due	1,103	950
Recorded investment, total	1,103	950
Land loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
Recorded investment, loans not past due	259	349
Recorded investment, total	259	349
Commercial loans - Secured [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
Recorded investment, loans not past due	40,935	26,480
Recorded investment, total	40,935	26,480
Commercial loans - Unsecured [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
Commercial Loans - Municipal loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
Commercial Loans - Warehouse Lines [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded investment, loans not past due	40,237	31,847
Recorded investment, total	40,237	31,847
Commercial Loans - Health Care [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded investment, loans not past due	71,738	41,086
Recorded investment, total	71,738	41,086
Commercial Leases - Investment rated commercial leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	934	51
Recorded investment, loans not past due	207,747	273,405
Recorded investment, total	208,681	273,456
Commercial Leases - Below Investment Grade [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	288	0
Recorded investment, loans not past due	102,873	84,988
Recorded investment, total	103,161	84,988
Consumer loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
Recorded investment, loans not past due	1,605	2,263
Recorded investment, total	1,605	2,263
30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	2,098	2,304
30-59 Days Past Due [Member] | One-to-four family residential real estate loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	86	984
30-59 Days Past Due [Member] | One-to-four family residential real estate loans - non-owner occupied loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	10	664
30-59 Days Past Due [Member] | Multi-family mortgage loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	172	605
30-59 Days Past Due [Member] | Wholesale commercial lending [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
30-59 Days Past Due [Member] | Nonresidential real estate loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	608	0
30-59 Days Past Due [Member] | Construction loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due		0
30-59 Days Past Due [Member] | Land loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
30-59 Days Past Due [Member] | Commercial loans - Secured [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
30-59 Days Past Due [Member] | Commercial Loans - Municipal loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
30-59 Days Past Due [Member] | Commercial Loans - Warehouse Lines [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
30-59 Days Past Due [Member] | Commercial Leases - Investment rated commercial leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	934	51
30-59 Days Past Due [Member] | Commercial Leases - Below Investment Grade [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	288	0
30-59 Days Past Due [Member] | Consumer loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	102	888
60-89 Days Past Due [Member] | One-to-four family residential real estate loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	99	335
60-89 Days Past Due [Member] | One-to-four family residential real estate loans - non-owner occupied loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	3	114
60-89 Days Past Due [Member] | Multi-family mortgage loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	439
60-89 Days Past Due [Member] | Wholesale commercial lending [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
60-89 Days Past Due [Member] | Nonresidential real estate loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
60-89 Days Past Due [Member] | Construction loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due		0
60-89 Days Past Due [Member] | Land loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
60-89 Days Past Due [Member] | Commercial loans - Secured [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
60-89 Days Past Due [Member] | Commercial Loans - Municipal loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
60-89 Days Past Due [Member] | Commercial Loans - Warehouse Lines [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
60-89 Days Past Due [Member] | Commercial loans - Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
60-89 Days Past Due [Member] | Commercial Leases - Investment rated commercial leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
60-89 Days Past Due [Member] | Consumer loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
90 Days or Greater Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	2,251	3,047
90 Days or Greater Past Due [Member] | One-to-four family residential real estate loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	1,801	2,235
90 Days or Greater Past Due [Member] | One-to-four family residential real estate loans - non-owner occupied loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	86	368
90 Days or Greater Past Due [Member] | Multi-family mortgage loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	364	184
90 Days or Greater Past Due [Member] | Wholesale commercial lending [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
90 Days or Greater Past Due [Member] | Nonresidential real estate loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	260
90 Days or Greater Past Due [Member] | Construction loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due		0
90 Days or Greater Past Due [Member] | Land loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
90 Days or Greater Past Due [Member] | Commercial loans - Secured [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
90 Days or Greater Past Due [Member] | Commercial Loans - Municipal loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
90 Days or Greater Past Due [Member] | Commercial Loans - Warehouse Lines [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
90 Days or Greater Past Due [Member] | Commercial Loans - Health Care [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
90 Days or Greater Past Due [Member] | Commercial loans - Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
90 Days or Greater Past Due [Member] | Commercial Leases - Investment rated commercial leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
90 Days or Greater Past Due [Member] | Consumer loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	$ 0	$ 0

Loans Receivable - Aging of Rec

Loans Receivable - Aging of Recorded Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	$ 4,451	$ 6,239
Recorded Investment, Loans Not Past Due	1,311,339	1,308,023
One-to-four family residential real estate loans - non-owner occupied loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	99	1,146
Recorded Investment, Loans Not Past Due	20,944	37,179
Multi-family mortgage loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	536	1,228
Recorded Investment, Loans Not Past Due	287,171	294,223
Construction loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due		0
Recorded Investment, Loans Not Past Due	1,103	950
Land loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
Recorded Investment, Loans Not Past Due	259	349
Commercial loans - Secured [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	0	0
Recorded Investment, Loans Not Past Due	40,935	26,480
Commercial loans - Unsecured [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Recorded Investment, Total Past Due	$ 0	$ 0

Loans Receivable - Troubled Deb

Loans Receivable - Troubled Debt Restructuring (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Troubled Debt Restructurings
Financing receivable modifications	$ 17	$ 341
One-to-four family residential real estate loans - non-owner occupied loans [Member] | Accrual Loans [Member]
Troubled Debt Restructurings
Financing receivable modifications	0	205
One-to-four family residential real estate loans - non-owner occupied loans [Member] | Non Accrual Loans [Member]
Troubled Debt Restructurings
Financing receivable modifications	$ 17	$ 136

Loans Receivable - Modified Tro

Loans Receivable - Modified Troubled Debt Restructuring (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)loan	Dec. 31, 2016USD ($)loan
Financing Receivable, Modifications [Line Items]
Loans modified	$ 149	$ 900
Loans by class modified as TDRs
Number of Loans | loan	0	1
Pre-Modification outstanding recorded investment	$ 0	$ 63
Post-Modification outstanding recorded investment	$ 0	63
Due to reduction in interest rate		0
Due to extension of maturity date		63
Due to permanent reduction in recorded investment		0
Total		$ 63

Loans Receivable - Troubled D62

Loans Receivable - Troubled Debt Restructuring - Payment Defaults (Details)	12 Months Ended
	Dec. 31, 2017USD ($)loan	Dec. 31, 2016USD ($)loan
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Increase In Allowance For Loan And Leases Losses	$ 0	$ 0
One-to-four family residential real estate loans [Member]
Loans by class modified as TDRs with payment default
Number of loans | loan	0	2
Recorded investment	$ 0	$ 87,000

Loans Receivable - Credit Quali

Loans Receivable - Credit Quality Indicators (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable Credit Quality Indicators
Total loans	$ 1,321,751	$ 1,319,416
One-to-four family residential real estate loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	97,814	135,218
One to Four Family Residential Real Estate Loans-Owner occupied [Member] [Member]
Financing Receivable Credit Quality Indicators
Total loans	76,606	96,629
One-to-four family residential real estate loans - non-owner occupied loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	21,208	38,589
Multi-family mortgage loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	588,383	542,887
Multi Family Mortgage Loans excluding wholesale [Member] [Member]
Financing Receivable Credit Quality Indicators
Total loans	291,358	299,183
Wholesale commercial lending [Member]
Financing Receivable Credit Quality Indicators
Total loans	297,025	243,704
Nonresidential real estate loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	169,971	182,152
Construction loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	1,099	946
Land loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	259	356
Commercial loans - Secured [Member]
Financing Receivable Credit Quality Indicators
Total loans	40,901	26,431
Commercial loans - Unsecured [Member]
Financing Receivable Credit Quality Indicators
Total loans	71,728	41,001
Commercial Loans - Municipal loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	39,923	31,681
Commercial Leases - Investment Rated [Member]
Financing Receivable Credit Quality Indicators
Total loans	207,460	271,972
Commercial Leases - Below Investment Grade [Member]
Financing Receivable Credit Quality Indicators
Total loans	102,616	84,517
Consumer loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	1,597	2,255
Nonaccrual [Member]
Financing Receivable Credit Quality Indicators
Total loans	2,391	3,302
Nonaccrual [Member] | One-to-four family residential real estate loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	1,914	2,486
Nonaccrual [Member] | One-to-four family residential real estate loans - non-owner occupied loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	109	369
Nonaccrual [Member] | Multi-family mortgage loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	368	187
Nonaccrual [Member] | Wholesale commercial lending [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Nonaccrual [Member] | Nonresidential real estate loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	260
Nonaccrual [Member] | Construction loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Nonaccrual [Member] | Land loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Nonaccrual [Member] | Commercial loans - Secured [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Nonaccrual [Member] | Commercial loans - Unsecured [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Nonaccrual [Member] | Commercial Loans - Municipal loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Nonaccrual [Member] | Commercial Leases - Investment Rated [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Nonaccrual [Member] | Commercial Leases - Below Investment Grade [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Nonaccrual [Member] | Consumer loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Special Mention [Member]
Financing Receivable Credit Quality Indicators
Total loans	4,528	1,083
Special Mention [Member] | One-to-four family residential real estate loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Special Mention [Member] | One-to-four family residential real estate loans - non-owner occupied loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Special Mention [Member] | Multi-family mortgage loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	122
Special Mention [Member] | Wholesale commercial lending [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Special Mention [Member] | Nonresidential real estate loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Special Mention [Member] | Construction loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Special Mention [Member] | Land loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Special Mention [Member] | Commercial loans - Secured [Member]
Financing Receivable Credit Quality Indicators
Total loans	4,528	0
Special Mention [Member] | Commercial loans - Unsecured [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Special Mention [Member] | Commercial Loans - Municipal loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	800
Special Mention [Member] | Commercial Leases - Investment Rated [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Special Mention [Member] | Commercial Leases - Below Investment Grade [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	161
Special Mention [Member] | Consumer loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Substandard [Member]
Financing Receivable Credit Quality Indicators
Total loans	2,922	3,629
Substandard [Member] | One-to-four family residential real estate loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	255	629
Substandard [Member] | One-to-four family residential real estate loans - non-owner occupied loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	40	41
Substandard [Member] | Multi-family mortgage loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	225	1,048
Substandard [Member] | Wholesale commercial lending [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Substandard [Member] | Nonresidential real estate loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	154	1,845
Substandard [Member] | Construction loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Substandard [Member] | Land loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Substandard [Member] | Commercial loans - Secured [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	66
Substandard [Member] | Commercial loans - Unsecured [Member]
Financing Receivable Credit Quality Indicators
Total loans	2,248	0
Substandard [Member] | Commercial Loans - Municipal loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Substandard [Member] | Commercial Leases - Investment Rated [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Substandard [Member] | Commercial Leases - Below Investment Grade [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Substandard [Member] | Consumer loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	0	0
Pass [Member]
Financing Receivable Credit Quality Indicators
Total loans	1,311,910	1,311,402
Pass [Member] | One-to-four family residential real estate loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	74,437	93,514
Pass [Member] | One-to-four family residential real estate loans - non-owner occupied loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	21,059	38,179
Pass [Member] | Multi-family mortgage loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	290,765	297,826
Pass [Member] | Wholesale commercial lending [Member]
Financing Receivable Credit Quality Indicators
Total loans	297,025	243,704
Pass [Member] | Nonresidential real estate loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	169,817	180,047
Pass [Member] | Construction loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	1,099	946
Pass [Member] | Land loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	259	356
Pass [Member] | Commercial loans - Secured [Member]
Financing Receivable Credit Quality Indicators
Total loans	36,373	26,365
Pass [Member] | Commercial loans - Unsecured [Member]
Financing Receivable Credit Quality Indicators
Total loans	69,480	41,001
Pass [Member] | Commercial Loans - Municipal loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	39,923	30,881
Pass [Member] | Commercial Leases - Investment Rated [Member]
Financing Receivable Credit Quality Indicators
Total loans	207,460	271,972
Pass [Member] | Commercial Leases - Below Investment Grade [Member]
Financing Receivable Credit Quality Indicators
Total loans	102,616	84,356
Pass [Member] | Consumer loans [Member]
Financing Receivable Credit Quality Indicators
Total loans	$ 1,597	$ 2,255

Loans Receivable - Narrative (D

Loans Receivable - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation of reserves allocation	$ 261,000	$ 434,000
Reserve For Uncollected Loan Interest	103,000	199,000
Financing receivable modifications	17,000	341,000
Outstanding Commitments To Borrowers Loans Classified As Troubled Debt Restructurings	0
Troubled Debt Restructurings Value Of Decreased Interest Income		0
Financing Receivable, Modifications, Increase In Allowance For Loan And Leases Losses		0
Increased value of allowances for loan losses	0	0
Charges regarding TDRs		0
Loans modified	149,000	900,000
Allowance for Loan and Lease Losses [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation of reserves allocation	$ 0	$ 0

Other Real Estate (Details)

Other Real Estate (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Real Estate, Disposals	$ (3,977,000)	$ (4,053,000)
other real estate owned at carrying value before valuation allowance	2,656,000	4,344,000
Real Estate Owned, Valuation Allowance	(305,000)	(449,000)	$ (1,042,000)
New foreclosed properties	2,766,000	1,251,000
Other Real Estate, Valuation Adjustments	(333,000)	(314,000)
Real Estate Owned, Valuation Allowance, Valuation Increase	333,000	314,000
reduction in valuation allowance for sales of OREO	(477,000)	(907,000)
Other Real Estate Owned At Carrying Value	2,351,000	3,895,000	$ 7,011,000
Mortgage Loans in Process of Foreclosure, Amount	900,000	1,600,000
One to Four Family Residential Real Estate Loans [Member]
other real estate owned at carrying value before valuation allowance	836,000	1,702,000
Real Estate Owned, Valuation Allowance	(9,000)	(137,000)
Other Real Estate Owned At Carrying Value	827,000	1,565,000
Multi Family Mortgage Loans [Member]
other real estate owned at carrying value before valuation allowance	0	370,000
Real Estate Owned, Valuation Allowance	0	0
Other Real Estate Owned At Carrying Value	0	370,000
Nonresidential Real Estate [Member]
other real estate owned at carrying value before valuation allowance	1,772,000	1,171,000
Real Estate Owned, Valuation Allowance	(252,000)	(105,000)
Other Real Estate Owned At Carrying Value	1,520,000	1,066,000
Land [Member]
other real estate owned at carrying value before valuation allowance	48,000	1,101,000
Real Estate Owned, Valuation Allowance	(44,000)	(207,000)
Other Real Estate Owned At Carrying Value	4,000	$ 894,000
Residential Real Estate [Member]
Repossessed assets	$ 352,000

Premises and Equipment - Year E

Premises and Equipment - Year End (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 55,482	$ 64,954
Accumulated depreciation	(30,626)	(33,541)
Property and equipment, net	24,856	31,413
Depreciation	2,000	2,000	$ 2,100
Premises held-for-sale	5,667	0
Land and land improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	12,265	13,820
Building and building improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	29,556	37,416
Furniture and equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	9,678	9,660
Computer equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 3,983	$ 4,058

Premises and Equipment - Schedu

Premises and Equipment - Schedule of Future Minimum Payments for Operating Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant, Equipment And Leases [Abstract]
Rent expense, net of sublease income	$ 477	$ 399	$ 393
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2,017	497
2,018	471
2,019	459
2,020	464
2,021	491
Thereafter	3,753
Total	$ 6,135

Premises and Equipment - Sche68

Premises and Equipment - Schedule of Future Proceeds for Subleases (Details) $ in Thousands	Dec. 31, 2017USD ($)
Property, Plant, Equipment And Leases [Abstract]
2,018	$ 2
2,019	2
2,020	2
2,021	1
2,022	1
Total	$ 8

Core Deposit Intangible - Sched

Core Deposit Intangible - Schedule of Finite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016
Finite-lived Intangible Assets [Roll Forward]
Amortization	$ (496)	$ (523)	$ (550)
Core Deposits [Member]
Finite-lived Intangible Assets [Roll Forward]
Balance at the beginning of the year	782	1,305
Amortization	(496)	(523)	(550)
Additions	0	0
Net Carrying Value	$ 782	$ 1,305	$ 1,305	$ 286	$ 782
Gross carrying amount				5,932	5,932
Accumulated amortization				$ (5,646)	$ (5,150)

Core Deposit Intangible - Sch70

Core Deposit Intangible - Schedule of Finite-Lived Intangible Assets Amortization Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of intangibles	$ 496	$ 523	$ 550
Core Deposits [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of intangibles	496	$ 523	$ 550
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2,015	184
2,016	61
2,017	34
2,018	7
2,019	$ 0

Deposits - Schedule of Deposits

Deposits - Schedule of Deposits By Type (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deposits [Abstract]
Noninterest-bearing demand deposits	$ 234,354	$ 249,539
Interest-bearing NOW accounts	289,657	267,054
Money market accounts	299,581	311,183
Savings deposits	160,501	160,002
Time Deposits	$ 355,958	$ 351,612

Deposits - Time Deposits, By Ma

Deposits - Time Deposits, By Maturity (Details) $ in Thousands	Dec. 31, 2017USD ($)
Deposits [Abstract]
2,017	$ 258,567
2,018	68,756
2,019	16,421
2,020	8,697
2,021	$ 3,517

Deposits - Narrative (Details)

Deposits - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Deposits [Abstract]
Time deposits, $100,000 or more	$ 50.3	$ 18.7

Repurchase Agreements (Details)

Repurchase Agreements (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Federal Home Loan Bank, Advances [Line Items]
Available-for-sale Securities Pledged as Collateral	$ 3,700	$ 4,700
Carrying Value of Federal Funds Purchased, Securities Sold under Agreements to Repurchase, and Deposits Received for Securities Loaned	768	1,069
Federal Home Loan Bank Advances [Member] | Within 1 year [Member]
Federal Home Loan Bank, Advances [Line Items]
Borrowings, Amount	$ 60,000	$ 50,000

Borrowings (Details)

Borrowings (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
First Mortgage [Member]
Debt Instrument [Line Items]
Collateral	$ 63,700
Multi-family mortgage loans [Member]
Debt Instrument [Line Items]
Collateral	$ 376,500
Federal Home Loan Bank Advances [Member] | Within 1 year [Member]
Debt Instrument [Line Items]
Borrowings, Contractual Rate	1.34%	0.67%
Borrowings, Amount	$ 60,000	$ 50,000
Federal Home Loan Bank Borrowings [Member]
Debt Instrument [Line Items]
Increase in line of credit	$ 322,200

Income Taxes - Schedule of Inco

Income Taxes - Schedule of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Current benefit									$ (2,658)	$ 308	$ 346
Deferred benefit									7,361	4,390	5,079
Deferred tax valuation allowance									2,487	0	0
Total income tax expense (benefit)	$ 4,702	$ 594	$ 1,572	$ 322	$ 1,458	$ 1,573	$ 514	$ 1,153	$ 7,190	$ 4,698	$ 5,425

Income Taxes - Schedule of Effe

Income Taxes - Schedule of Effective Income Tax Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Benefit computed at the statutory federal tax rate									$ 5,506	$ 4,148	$ 4,794
State taxes and other, net									(204)	464	626
Bank owned life insurance									(90)	(70)	(66)
ESOP/Share based compensation									(509)	156	71
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	$ 2,500								2,487	0	0
Total income tax expense (benefit)	$ 4,702	$ 594	$ 1,572	$ 322	$ 1,458	$ 1,573	$ 514	$ 1,153	$ 7,190	$ 4,698	$ 5,425
Effective income tax rate									44.77%	38.51%	38.48%

Income Taxes - Schedule of Defe

Income Taxes - Schedule of Deferred Tax Assets, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Gross Deferred tax assets:
Allowance for loan losses	$ 2,258	$ 3,117
Alternative minimum tax, general business credit and net operating loss carryforward	11,864	20,857
Tax deductible goodwill	801	1,466
Other	1,395	2,540
Total deferred tax assets, gross	16,318	27,980
Gross Deferred tax liabilities:
Net deferred loan origination costs	(1,255)	(1,874)
Purchase accounting adjustments	(1,744)	(2,644)
Other	(619)	(817)
Unrealized gain on securities	(137)	(234)
Gross deferred tax liabilities:	(3,755)	(5,569)
Net deferred tax asset	$ 12,563	$ 22,411

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Balances Roll-forward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning of year	$ 57	$ 108
Additions based on tax positions related to the current year	60	0
Additions for tax positions of prior years	12	0
Reductions due to the statute of limitations	0	(51)
End of year	$ 129	$ 57

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Statutory federal corporate tax rate		34.00%	34.00%	34.00%
Deferred tax not recongized	$ 14,900	$ 14,900	$ 14,900
Deferred Tax Assets, Net	12,563	12,563	22,411
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	$ 2,500	$ 2,487	$ 0	$ 0

Income Taxes - Narrative Tax Ca

Income Taxes - Narrative Tax Carryforwards (Details) $ in Millions	Dec. 31, 2017USD ($)
Alternative Minimum Tax Carryforward Axis [Member]
Tax Credit Carryforward [Line Items]
Tax credit carryforward	$ 3.1
Internal Revenue Service (IRS) [Member]
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	21.3
Tax credit carryforward	1.3
State and Local Jurisdiction [Member]
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	70.2
Downers Grove National Bank [Member]
Tax Credit Carryforward [Line Items]
Operating loss carryforwards	$ 7.6

Regulatory Matters - Requiremen

Regulatory Matters - Requirements (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Risk Based Ratios [Abstract]
Common Tier 1 Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%	4.50%
BankFinancial NA [Member]
Capital [Abstract]
Total capital (to risk-weighted assets), Actual, Amount	$ 188,582	$ 168,113
Total capital (to risk-weighted assets), Minimum required To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	91,572	91,386
Total capital (to risk-weighted assets), Minimum Capital Ratios Established under Capital Plans, Amount	114,466	114,232
Tier One Risk Based Capital [Abstract]
Tier 1 (core) capital (to risk-weighted assets), Actual, Amount	180,216	159,986
Tier 1 (core) capital (to risk-weighted assets), Minimum required To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	68,679	68,539
Tier 1 (core) capital (to risk-weighted assets), Minimum Capital Ratios Established under Capital Plans, Amount	91,572	91,386
Tier One Leverage Capital [Abstract]
Tier 1 (core) capital (to adjusted average total assets), Actual, Amount	180,216	159,986
Tier 1 (core) capital (to adjusted average total assets), Minimum required To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	65,045	62,303
Tier 1 (core) capital (to adjusted average total assets), Minimum Capital Ratios Established under Capital Plans, Amount	$ 81,307	$ 77,879
Risk Based Ratios [Abstract]
Total capital (to risk-weighted assets), Actual, Ratio	16.48%	14.72%
Total capital (to risk-weighted assets), For Capital Adequacy Purposes, Ratio	8.00%	8.00%
Total capital (to risk-weighted assets), Minimum Capital Ratios Established under Capital Plans, Ratio	10.00%	10.00%
Tier 1 (core) capital (to risk-weighted assets), Actual, Ratio	15.74%	14.01%
Tier 1 (core) capital (to risk-weighted assets), Minimum required To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	6.00%	6.00%
Tier 1 (core) capital (to risk-weighted assets), Minimum Capital Ratios Established under Capital Plans, Ratio	8.00%	8.00%
CET common tier 1 equity	$ 180,216	$ 159,986
Common Tier 1 to Risk Weighted Assets	15.74%	14.01%
Common Tier 1 Risk Based Capital Required for Capital Adequacy	$ 51,509	$ 51,404
Common Tier 1 Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%	4.50%
Common Tier One Capital required to be well capitalized	$ 74,403	$ 74,251
Common Tier One Risk Weighted Assets Required to be Well Capitalized to Risk Weighted Assets	6.50%	6.50%
Leverage Ratios [Abstract]
Tier 1 (core) capital (to adjusted average total assets), Actual, Ratio	11.08%	10.27%
Tier 1 (core) capital (to adjusted average total assets), Minimum required To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	4.00%	4.00%
Tier 1 (core) capital (to adjusted average total assets), Minimum Capital Ratios Established under Capital Plans, Ratio	5.00%	5.00%
Consolidated Entities [Member]
Capital [Abstract]
Total capital (to risk-weighted assets), Actual, Amount	$ 195,371	$ 193,845
Total capital (to risk-weighted assets), Minimum required To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	91,590	91,414
Tier One Risk Based Capital [Abstract]
Tier 1 (core) capital (to risk-weighted assets), Actual, Amount	187,005	185,718
Tier 1 (core) capital (to risk-weighted assets), Minimum required To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	68,692	68,560
Tier One Leverage Capital [Abstract]
Tier 1 (core) capital (to adjusted average total assets), Minimum required To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 65,085	$ 62,306
Risk Based Ratios [Abstract]
Total capital (to risk-weighted assets), Actual, Ratio	17.06%	16.96%
Total capital (to risk-weighted assets), For Capital Adequacy Purposes, Ratio	8.00%	8.00%
Tier 1 (core) capital (to risk-weighted assets), Actual, Ratio	16.33%	16.25%
Tier 1 (core) capital (to risk-weighted assets), Minimum required To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	6.00%	6.00%
CET common tier 1 equity	$ 187,005	$ 185,718
Common Tier 1 to Risk Weighted Assets	16.33%	16.25%
Common Tier 1 Risk Based Capital Required for Capital Adequacy	$ 51,519	$ 51,420
Leverage Ratios [Abstract]
Tier 1 (core) capital (to adjusted average total assets), Actual, Ratio	11.49%	11.92%
Tier 1 (core) capital (to adjusted average total assets), Minimum required To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	4.00%	4.00%

Regulatory Matters - Narrative

Regulatory Matters - Narrative (Details) $ in Millions	Dec. 31, 2017USD ($)
Minimum [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Cash to be held	$ 5

Employee Benefit Plans - Employ

Employee Benefit Plans - Employee Stock Ownership Plan (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 29, 2017	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jun. 23, 2005
Compensation Related Costs, Retirement and Share Based Payment [Line Items]
ESOP compensation expense		$ 1,100	$ 1,100	$ 1,300	$ 1,000
Loan receivable from ESOP						$ 19,600
ESOP issued price (usd per share)			$ 10
ESOP cash contributions			$ 1,100	1,500
ESOP, dividends and interest received			$ 50	$ 195
Employee Stock Ownership Plan (ESOP), Shares in ESOP [Abstract]
Allocated to participants (shares)			1,203,810	1,125,448
Distributed to participants			(317,914)	(313,223)
Unearned (shares)			0	831,852
Total ESOP shares (shares)	78,362		885,896	1,644,077
Fair value of unearned shares			$ 0	$ 12,328
Common Stock [Member]
Compensation Related Costs, Retirement and Share Based Payment [Line Items]
Repayments of Debt, Equity Instrument Consideration, Shares Issued	753,490
ESOP shares purchased (shares)			1,957,300
Share Acquisition Loan [Member]
Compensation Related Costs, Retirement and Share Based Payment [Line Items]
Loans Payable			$ 0	$ 10,800

Employee Benefit Plans - Empl85

Employee Benefit Plans - Employee Stock Ownership Plan - Profit Sharing 401(k) Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Age for eligibility for Employee Benefits	21 years
Employee benefit plans, requisite time for service	1 year
Employee matching ratio	50.00%
Maximum annual contribution per employee	6.00%
Contribution plan expenses	$ 328	$ 330	$ 308

Equity Incentive Plans - Narrat

Equity Incentive Plans - Narrative (Details) - USD ($) $ in Thousands	Jun. 27, 2006	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
restricted stock available for grant		0
Stock Options Outstanding		0	1,752,156	1,752,156
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		0
Share-based compensation expense		$ 0	$ 979	$ 568
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized		$ 8
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross		1,752,156
Share-based Compensation Arrangement by Share-based Payment Award, Net Settlement Share Issuance		280,554
Share-based Compensation Arrangement by Share-based Payment Award, Shares Withheld For Taxes		82,528
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period		198,026
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms		9 years 1 month 23 days
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense		$ 0	$ 3	$ 70
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms		0 days	8 months 27 days
Restricted Stock [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		3 years
Restricted Stock [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		5 years
2006 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (shares)	3,425,275
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	10 years

Equity Incentive Plans - Schedu

Equity Incentive Plans - Schedule of Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Stock Options Outstanding	0	1,752,156	1,752,156
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price	$ 0	$ 12.30	$ 12.30
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	1 day	5 months 23 days	1 year 5 months 23 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value			$ 778
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value	$ 0	$ 4,422
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	(1,752,156)

Equity Incentive Plans - Sche88

Equity Incentive Plans - Schedule of Restricted Stock Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms	9 years 1 month 23 days
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term			3 months 22 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Shares outstanding, beginning balance (shares)	940	7,934
Shares granted (shares)	0	0
Shares vested (shares)	0	(6,994)
Shares forfeited (shares)	0	0
Shares outstanding, ending balance (shares)	940	940	7,934
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Shares outstanding, beginning balance, Weighted Average Fair Value at Grant Date (usd per share)	$ 8.14	$ 8.14
Shares granted, Weighted Average Fair Value at Grant Date (usd per share)	0	0
Shares vested, Weighted Average Fair Value at Grant Date (usd per share)	0	0
Shares forfeited, Weighted Average Fair Value at Grant Date (usd per share)	0	0
Shares outstanding, ending balance, Weighted Average Fair Value at Grant Date (usd per share)	$ 8.14	$ 8.14	$ 8.14
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms	0 days	8 months 27 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Outstanding	$ 14	$ 14	$ 100

Loan Commitments and Other Of89

Loan Commitments and Other Off-Balance Sheet Activities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2007
Guarantor Obligations [Line Items]
Duration of extension	60 days
Commitments to extend credit [Member]
Guarantor Obligations [Line Items]
Notional Or Contractual Credit Extension Commitments	$ 46,615	$ 91,172
Fixed-rate loan commitments	19,200
Standby letters of credit [Member]
Guarantor Obligations [Line Items]
Notional Or Contractual Credit Extension Commitments	6,757	1,305
Unused lines of credit [Member]
Guarantor Obligations [Line Items]
Notional Or Contractual Credit Extension Commitments	129,207	125,332
Commitments to sell mortgages [Member]
Guarantor Obligations [Line Items]
Notional Or Contractual Credit Extension Commitments	$ 0	$ 0
Minimum [Member] | Commitments to extend credit [Member]
Guarantor Obligations [Line Items]
Fixed interest rate	3.00%
Maturity period	1 year
Maximum [Member] | Commitments to extend credit [Member]
Guarantor Obligations [Line Items]
Fixed interest rate	6.00%
Maturity period	30 years
Unrestricted [Member] | Common Class B [Member] | Visa USA [Member]
Guarantor Obligations [Line Items]
Shares owned (shares)			51,404
Litigation Escrow Deposit May Be Converted Into Publicly Traded Class A Common Shares [Member] | Common Class B [Member] | Visa USA [Member]
Guarantor Obligations [Line Items]
Shares owned (shares)			32,398

Fair Value - Financial Assets A

Fair Value - Financial Assets Accounted for at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale Securities, Debt Securities	$ 92,884
Nonrecurring [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale Securities, Debt Securities	93,383	$ 107,212
Nonrecurring [Member] | Certificates of deposit [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale Securities, Debt Securities	75,916	85,938
Nonrecurring [Member] | Equity mutual fund [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale Securities, Debt Securities	499	499
Nonrecurring [Member] | Mortgage-backed securities - residential [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale Securities, Debt Securities	12,472	15,184
Nonrecurring [Member] | Collateralized mortgage obligations - residential [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale Securities, Debt Securities	4,486	5,574
Nonrecurring [Member] | SBA-guaranteed loan participation certificates [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale Securities, Debt Securities	10	17
Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale Securities, Debt Securities	499	499
Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Certificates of deposit [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale Securities, Debt Securities	0
Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mortgage-backed securities - residential [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale Securities, Debt Securities	0
Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Collateralized mortgage obligations - residential [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale Securities, Debt Securities	0
Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | SBA-guaranteed loan participation certificates [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale Securities, Debt Securities	0
Nonrecurring [Member] | Significant Observable Inputs (Level 2) [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale Securities, Debt Securities	92,884	106,713
Nonrecurring [Member] | Significant Observable Inputs (Level 2) [Member] | Equity mutual fund [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale Securities, Debt Securities	0
Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale Securities, Debt Securities	0	$ 0
Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Certificates of deposit [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale Securities, Debt Securities	0
Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Equity mutual fund [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale Securities, Debt Securities	0
Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage-backed securities - residential [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale Securities, Debt Securities	0
Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Collateralized mortgage obligations - residential [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale Securities, Debt Securities	0
Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | SBA-guaranteed loan participation certificates [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale Securities, Debt Securities	$ 0

Fair Value - Assets Measured at

Fair Value - Assets Measured at Fair Value on a Non-Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Other real estate owned	$ 900	$ 1,900
Mortgage servicing rights	513	612
Nonrecurring [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Impaired loans		234
Fair Value, Other real estate owned	916	1,882
Nonrecurring [Member] | One-to-four family residential real estate loans [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Other real estate owned	102	1,282
Nonrecurring [Member] | Nonresidential real estate loans [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Impaired loans		234
Fair Value, Other real estate owned	814	553
Nonrecurring [Member] | Land loans [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Other real estate owned		47
Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Impaired loans		0
Fair Value, Other real estate owned	0	0
Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | One-to-four family residential real estate loans [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Other real estate owned	0	0
Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Nonresidential real estate loans [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Impaired loans		0
Fair Value, Other real estate owned	0	0
Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Land loans [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Other real estate owned		0
Nonrecurring [Member] | Significant Observable Inputs (Level 2) [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Impaired loans		0
Fair Value, Other real estate owned	0	0
Nonrecurring [Member] | Significant Observable Inputs (Level 2) [Member] | One-to-four family residential real estate loans [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Other real estate owned	0	0
Nonrecurring [Member] | Significant Observable Inputs (Level 2) [Member] | Nonresidential real estate loans [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Impaired loans		0
Fair Value, Other real estate owned	0	0
Nonrecurring [Member] | Significant Observable Inputs (Level 2) [Member] | Land loans [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Other real estate owned		0
Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Impaired loans		234
Fair Value, Other real estate owned	$ 916	$ 1,882

Fair Value - Level 3 Fair Value

Fair Value - Level 3 Fair Value Measurements for Financial Instruments on a Non-recurring Basis (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities	$ 92,884
Fair Value, Other real estate owned	900	$ 1,900
Fair value of mortgage servicing rights	513	612
Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Impaired loans		234
Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Other real estate owned	$ 916	$ 1,882
One to Four Family Residential Real Estate Loans [Member] | Sales comparison [Member] | Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements, Sensitivity Analysis, Description		Comparison between sales and income approaches
One to Four Family Residential Real Estate Loans [Member] | Sales comparison [Member] | Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements, Valuation Processes, Description	Sales comparison	Sales comparison
Fair Value Measurements, Sensitivity Analysis, Description	Discount applied to valuation	Discount applied to valuation
One to Four Family Residential Real Estate Loans [Member] | Sales comparison [Member] | Minimum [Member] | Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weigthed Average), Discount applied to valuation		20.04%
One to Four Family Residential Real Estate Loans [Member] | Sales comparison [Member] | Maximum [Member] | Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weigthed Average), Discount applied to valuation		8.62%
One to Four Family Residential Real Estate Loans [Member] | Sales comparison [Member] | Weighted Average [Member] | Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weigthed Average), Discount applied to valuation	5.60%	11.90%
Nonresidential real estate loans [Member] | Sales comparison [Member] | Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements, Valuation Processes, Description		Sales comparison
Nonresidential real estate loans [Member] | Sales comparison [Member] | Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements, Valuation Processes, Description	Sales comparison	Sales comparison
Fair Value Measurements, Sensitivity Analysis, Description	Comparison between sales and income approaches	Comparison between sales and income approaches
Nonresidential real estate loans [Member] | Sales comparison [Member] | Minimum [Member] | Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average), Comparison between sales and income approaches	15.22%	4.58%
Nonresidential real estate loans [Member] | Sales comparison [Member] | Maximum [Member] | Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average), Comparison between sales and income approaches	(3.66%)	(3.22%)
Nonresidential real estate loans [Member] | Sales comparison [Member] | Weighted Average [Member] | Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average), Comparison between sales and income approaches		(10.20%)
Nonresidential real estate loans [Member] | Sales comparison [Member] | Weighted Average [Member] | Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average), Comparison between sales and income approaches	(11.00%)	3.70%
Land [Member] | Sales comparison [Member] | Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements, Valuation Processes, Description	Sales comparison
Fair Value Measurements, Sensitivity Analysis, Description	Discount applied to valuation
Land [Member] | Sales comparison [Member] | Minimum [Member] | Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weigthed Average), Discount applied to valuation		31.60%
Land [Member] | Sales comparison [Member] | Maximum [Member] | Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weigthed Average), Discount applied to valuation		5.74%
Land [Member] | Sales comparison [Member] | Weighted Average [Member] | Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weigthed Average), Discount applied to valuation		25.20%
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities	$ 93,383	$ 107,212
Fair Value, Impaired loans		234
Fair Value, Other real estate owned	916	1,882
Fair Value, Measurements, Nonrecurring [Member] | One to Four Family Residential Real Estate Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Other real estate owned	102	1,282
Fair Value, Measurements, Nonrecurring [Member] | Nonresidential real estate loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Impaired loans		234
Fair Value, Other real estate owned	814	553
Fair Value, Measurements, Nonrecurring [Member] | Land [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Other real estate owned		47
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities	0	0
Fair Value, Impaired loans		234
Fair Value, Other real estate owned	916	1,882
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member] | One to Four Family Residential Real Estate Loans [Member] | Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Other real estate owned	102	1,282
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Nonresidential real estate loans [Member] | Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Impaired loans		234
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Nonresidential real estate loans [Member] | Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Other real estate owned	$ 814	553
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Land [Member] | Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Other real estate owned		$ 47

Fair Value - Carrying Amount an

Fair Value - Carrying Amount and Estimated Fair Value of Finanical Instruments (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Valuation Allowances and Reserves, Balance	$ (261,000)	$ (434,000)
Fair value of mortgage servicing rights	513,000	612,000
Financial assets
Cash and cash equivalents, carrying amount	127,592,000	96,684,000	$ 59,377,000	$ 59,581,000
Cash and Due from Banks	13,572,000	13,053,000
Interest-bearing Deposits in Banks and Other Financial Institutions	114,020,000	83,631,000
Marketable Securities	93,383,000	107,212,000
Securities, carrying amount	92,884,000
Securities, fair value	93,383,000	107,212,000
Loans receivable, net of allowance for loan losses, carrying amounts	1,314,651,000	1,312,952,000
FHLBC stock, carrying amount	8,290,000	11,650,000
Accrued interest receivable, carrying amount	4,619,000	4,381,000
Financial liabilities
Noninterest-bearing demand deposits	234,354,000	249,539,000
Savings deposits	160,501,000	160,002,000
Time Deposits	355,958,000	351,612,000
Borrowings	60,768,000	51,069,000
Carrying Amount [Member]
Financial liabilities
NOW and money market accounts, carrying amount	589,238,000	578,237,000
Accrued interest payable, carrying amount	147,000	102,000
Estimated Fair Value [Member]
Financial assets
Cash and cash equivalents, fair value	127,592,000	96,684,000
Securities, fair value	93,383,000	107,212,000
Loans receivable, net of allowance for loan losses, fair value	1,323,139,000	1,322,947,000
Accounts interest receivable, fair value	4,619,000	4,381,000
Financial liabilities
Non-interest-bearing demand deposits, fair value	234,354,000	249,539,000
NOW money market accounts, fair value	589,238,000	578,237,000
Savings deposits, fair value	160,501,000	160,002,000
Certificates of deposit, fair value	353,969,000	350,593,000
Borrowings, fair value	60,627,000	50,015,000
Accrued interest payable, fair value	147,000	102,000
Estimated Fair Value [Member] | Fair Value, Inputs, Level 1 [Member]
Financial assets
Loans receivable, net of allowance for loan losses, fair value	0	0
Accounts interest receivable, fair value	0	0
Financial liabilities
Non-interest-bearing demand deposits, fair value	0	0
Savings deposits, fair value	0	0
Certificates of deposit, fair value	0	0
Borrowings, fair value	0	0
Accrued interest payable, fair value	0	0
Estimated Fair Value [Member] | Level 2 [Member]
Financial assets
Securities, fair value	92,884,000	106,713,000
Loans receivable, net of allowance for loan losses, fair value	1,323,139,000	1,322,713,000
Accounts interest receivable, fair value	4,619,000	4,381,000
Financial liabilities
Non-interest-bearing demand deposits, fair value	234,354,000	249,539,000
NOW money market accounts, fair value	589,238,000	578,237,000
Savings deposits, fair value	160,501,000	160,002,000
Certificates of deposit, fair value	353,969,000	350,593,000
Borrowings, fair value	60,627,000	50,015,000
Accrued interest payable, fair value	147,000	102,000
Estimated Fair Value [Member] | Fair Value, Inputs, Level 3 [Member]
Financial assets
Cash and cash equivalents, fair value	0	0
Securities, fair value	0	0
Loans receivable, net of allowance for loan losses, fair value	0	234,000
Accounts interest receivable, fair value	0	0
Financial liabilities
Non-interest-bearing demand deposits, fair value	0	0
Savings deposits, fair value	0	0
Certificates of deposit, fair value	0	0
Borrowings, fair value	0	0
Accrued interest payable, fair value	0	0
Equity Funds [Member]
Financial assets
Securities, fair value	499,000	499,000
Fair Value, Measurements, Nonrecurring [Member]
Financial assets
Securities, carrying amount	93,383,000	107,212,000
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Financial assets
Securities, carrying amount	499,000	499,000
Fair Value, Measurements, Nonrecurring [Member] | Level 2 [Member]
Financial assets
Securities, carrying amount	92,884,000	106,713,000
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Financial assets
Securities, carrying amount	0	0
Fair Value, Measurements, Nonrecurring [Member] | Collateralized Mortgage Obligations Residential [Member]
Financial assets
Securities, carrying amount	4,486,000	$ 5,574,000
Fair Value, Measurements, Nonrecurring [Member] | Collateralized Mortgage Obligations Residential [Member] | Fair Value, Inputs, Level 1 [Member]
Financial assets
Securities, carrying amount	0
Fair Value, Measurements, Nonrecurring [Member] | Collateralized Mortgage Obligations Residential [Member] | Fair Value, Inputs, Level 3 [Member]
Financial assets
Securities, carrying amount	$ 0

Fair Value - Narratives (Detail

Fair Value - Narratives (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Loans Carrying Amount		$ 260
other real estate owned with an allowance at carrying value before valuation allowance	$ 1,200	2,300
Impaired loans, valuation allowance		26
Provision for Loan and Lease Losses	0	18
Other real estate owned at carrying value	2,351	3,895	$ 7,011
Real Estate Acquired Through Foreclosure Fair Value	900	1,900
Real Estate Owned, Valuation Allowance, Valuation Increase	333	314
Other Real Estate, Valuation Adjustments	333	314
Fair value of mortgage servicing rights	513	612
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real Estate Acquired Through Foreclosure Fair Value	916	1,882
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real Estate Acquired Through Foreclosure Fair Value	$ 916	$ 1,882

Company Only Condensed Financ95

Company Only Condensed Financial Information - Statements of Financial Condition (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jun. 23, 2005
Assets
Loan receivable from ESOP					$ 19,600
Deferred Tax Assets, Net	$ 12,563	$ 22,411
Other assets	8,441	6,063
Total assets	1,625,558	1,620,037
Liabilities and Stockholders' Equity
Total stockholders’ equity	197,634	204,780	$ 212,364	$ 216,121
Total liabilities and stockholders' equity	1,625,558	1,620,037
Parent Company [Member]
Assets
Cash in subsidiary	6,393	14,543	$ 15,309	$ 9,724
Loan receivable from ESOP	0	10,767
Investment in subsidiary	188,873	176,756
Deferred Tax Assets, Net	2,076	2,367
Other assets	3,307	347
Total assets	200,649	204,780
Liabilities and Stockholders' Equity
Accrued expenses and other liabilities	3,015	0
Total stockholders’ equity	197,634	204,780
Total liabilities and stockholders' equity	$ 200,649	$ 204,780

Company Only Condensed Financ96

Company Only Condensed Financial Information - Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Interest income	$ 13,305	$ 12,506	$ 12,193	$ 12,086	$ 11,595	$ 11,831	$ 11,629	$ 11,903	$ 50,090	$ 46,958	$ 46,148
Other expense	(9,318)	(10,200)	(9,607)	(11,266)	(10,194)	(9,912)	(10,506)	(10,930)	(40,391)	(41,542)	(41,945)
Income (loss) before income taxes	5,693	4,154	4,144	2,203	3,717	4,081	1,345	3,057	16,194	12,200	14,100
Income tax expense	$ 4,702	$ 594	$ 1,572	$ 322	$ 1,458	$ 1,573	$ 514	$ 1,153	7,190	4,698	5,425
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Interest income									110	503	544
Dividends from subsidiary									10,629	16,888	19,710
Other expense									(1,693)	(1,846)	(1,536)
Income (loss) before income taxes									9,046	15,545	18,718
Income tax expense									290	(502)	(783)
Loss before equity in undistributed subsidiary income									8,756	16,047	19,501
Equity in undistributed subsidiary excess distributions									248	(8,545)	(10,826)
Net income (loss)									$ 9,004	$ 7,502	$ 8,675

Company Only Condensed Financ97

Company Only Condensed Financial Information - Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Adjustments:
Change in other assets	$ (3,406)	$ (1,418)	$ 659
Net Cash Provided by (Used in) Operating Activities	22,730	18,941	14,882
Cash flows from investing activities
Net cash from (used in) investing activities	14,405	(77,021)	(53,613)
Cash flows from financing activities
Repurchase and retirement of common stock	(10,819)	(13,215)	(9,970)
Cash dividends paid on common stock	(5,153)	(4,133)	(4,145)
Net cash used in financing activities	(6,227)	95,387	38,527
Parent Company [Member]
Cash flows from operating activities
Net income (loss)	9,004	7,502	8,675
Adjustments:
Equity in undistributed subsidiary excess distributions	(248)	8,545	10,826
Change in other assets	(2,712)	(497)	(793)
Change in accrued expenses and other liabilities	3,015	0	0
Net Cash Provided by (Used in) Operating Activities	9,059	15,550	18,708
Cash flows from investing activities
Principal payments received on ESOP loan	0	1,032	992
Net cash from (used in) investing activities	0	1,032	992
Cash flows from financing activities
Net exercise of stock options	(1,237)	0	0
Repurchase and retirement of common stock	(10,819)	(13,215)	(9,970)
Cash dividends paid on common stock	(5,153)	(4,133)	(4,145)
Net cash used in financing activities	(17,209)	(17,348)	(14,115)
Net change in cash in subsidiary	(8,150)	(766)	5,585
Beginning cash in subsidiary	14,543	15,309	9,724
Ending cash in subsidiary	$ 6,393	$ 14,543	$ 15,309

Selected Quarterly Financial 98

Selected Quarterly Financial Data (unaudited) (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Interest income	$ 15,047	$ 14,121	$ 13,649	$ 13,362	$ 12,743	$ 12,845	$ 12,581	$ 12,759	$ 56,179	$ 50,928	$ 48,962
Interest expense	1,742	1,615	1,456	1,276	1,148	1,014	952	856	6,089	3,970	2,814
Net interest income	13,305	12,506	12,193	12,086	11,595	11,831	11,629	11,903	50,090	46,958	46,148
Provision for (recovery of) loan losses	(72)	(225)	49	161	(539)	(525)	1,315	(490)	(87)	(239)	(3,206)
Net interest income	13,377	12,731	12,144	11,925	12,134	12,356	10,314	12,393	50,177	47,197	49,354
Noninterest Income	1,634	1,623	1,607	1,544	1,777	1,637	1,537	1,594	6,408	6,545	6,691
Noninterest expense	9,318	10,200	9,607	11,266	10,194	9,912	10,506	10,930	40,391	41,542	41,945
Income (loss) before income taxes	5,693	4,154	4,144	2,203	3,717	4,081	1,345	3,057	16,194	12,200	14,100
Income tax expense	4,702	594	1,572	322	1,458	1,573	514	1,153	7,190	4,698	5,425
Net income (loss)	$ 991	$ 3,560	$ 2,572	$ 1,881	$ 2,259	$ 2,508	$ 831	$ 1,904	$ 9,004	$ 7,502	$ 8,675
Earnings Per Share, Basic	$ 0.06	$ 0.20	$ 0.14	$ 0.10		$ 0.13	$ 0.04	$ 0.10	$ 0.49	$ 0.40	$ 0.44
Diluted earnings (loss) per common share (usd per share)		$ 0.20	$ 0.14	$ 0.10	$ 0.12	$ 0.13	$ 0.04	$ 0.10	$ 0.49	$ 0.39	$ 0.44

Selected Quarterly Financial 99

Selected Quarterly Financial Data (unaudited) (Narrative) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Effect of Fourth Quarter Events [Line Items]
Net income	$ 991,000	$ 3,560,000	$ 2,572,000	$ 1,881,000	$ 2,259,000	$ 2,508,000	$ 831,000	$ 1,904,000	$ 9,004,000	$ 7,502,000	$ 8,675,000
Earnings Per Share, Basic and Diluted	$ 0.06				$ 0.12
Interest income	$ 13,305,000	12,506,000	12,193,000	12,086,000	$ 11,595,000	11,831,000	11,629,000	11,903,000	50,090,000	46,958,000	46,148,000
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	2,500,000								2,487,000	0	0
Provision for (recovery of) loan losses	$ 72,000	$ 225,000	$ (49,000)	$ (161,000)	539,000	$ 525,000	$ (1,315,000)	$ 490,000	87,000	239,000	3,206,000
Gain (Loss) on Disposition of Property Plant Equipment					113,000				0	38,000	(1,000)
Asset management costs					$ 177,000				$ 340,000	$ 399,000	$ 681,000