Document And Entity Information Document Information [Table] Document Information [Line Items] Document Type Document Quarterly Report Document Transition Report Document Period End Date Current Fiscal Year End Date Document Fiscal Year Focus Securities Act File Number Entity Registrant Name Entity Incorporation, State or Country Code Entity Tax Identification Number Entity Address, Address Line One Entity Address, City or Town Entity Address, State or Province Entity Address, Postal Zip Code City Area Code Local Phone Number Title of 12(b) Security Trading Symbol Security Exchange Name Entity Current Reporting Status Entity Interactive Data Current Entity Filer Category Entity Small Business Entity Emerging Growth Company Entity Shell Company Entity Common Stock, Shares Outstanding Entity Central Index Key Document Fiscal Period Focus Amendment Flag Consolidated Statements of Financial Condition Statement [Table] Statement [Line Items] Assets [Abstract] Assets Cash and Due from Banks Cash and due from banks (restricted cash of $16,615 for both periods) Debt Securities, Held-to-Maturity, Excluding Accrued Interest, after Allowance for Credit Loss Securities held-to-maturity, net of allowance of $338 and $348, respectively (assets pledged of $4,689 and $4,695, respectively; fair value of $45,212 and $46,232, respectively) Securities held-to-maturity, Net Carrying Amount Securities held-to-maturity, Net Carrying Amount Debt Securities, Available-for-Sale, Excluding Accrued Interest Total Securities available for sale, Fair Value Total securities available for sale, Fair Value Securities available for sale, at fair value (amortized cost of $1,633,466 and $1,387,619, respectively; net of an allowance of $2,774 and $2,921, respectively; assets pledged of $102,369 and $115,974, respectively; $14,527 and $14,412 at fair value pursuant to the fair value option, respectively) Financing Receivable, Excluding Accrued Interest, after Allowance for Credit Loss [Abstract] Loans: Amortized cost excluding accrued interest, after portfolio layer basis adjustments, of financing receivable. Excludes net investment in lease. Financing Receivable Excluding Accrued Interest After Portfolio Layer Basis Adjustments Loans held for investment, net of fees and costs Total loans, net of fees and costs Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest Less: Allowance for credit losses Ending balance Beginning balance Allowance for credit losses - loans Financing Receivable, Excluding Accrued Interest, after Allowance for Credit Loss Net loans held of investment Net loans held for investment Accrued Investment Income Receivable Interest and dividends receivable Property, Plant and Equipment, Net Bank premises and equipment, net Federal Home Loan Bank Stock Federal Home Loan Bank of New York stock, at cost Bank Owned Life Insurance Bank owned life insurance Finite-Lived Core Deposits, Gross Core deposit intangibles Operating Lease, Right-of-Use Asset Right-of-use assets Operating lease ROU assets Other Assets Other assets Assets Total assets Liabilities [Abstract] Liabilities Noninterest-Bearing Deposit Liabilities, Domestic Non-interest bearing Interest-Bearing Deposit Liabilities, Domestic Interest-bearing The aggregate amount of all domestic and foreign noninterest-bearing and interest-bearing deposits liabilities held by the entity. Deposit Liabilities Total Due to depositors Mortgagors' escrow deposits Debt and Lease Obligation [Abstract] Borrowed funds: Amount of unsecured debt and borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages. Advances from Federal Home Loan Banks and Unsecured Debt Federal Home Loan Bank advances and other borrowings Subordinated Debt Subordinated debentures Junior Subordinated Notes Junior subordinated debentures, at fair value Debt and Lease Obligation Total borrowed funds Operating Lease, Liability Operating lease liabilities Operating lease liability Total lease obligations Other liabilities Liabilities Total liabilities Equity, Attributable to Parent [Abstract] Stockholders' Equity Preferred Stock, Value, Issued Preferred stock ($0.01 par value; 5,000,000 shares authorized; none issued) Common Stock, Value, Issued Common stock ($0.01 par value; 100,000,000 shares authorized; 38,677,787 shares issued; 33,883,626 and 33,778,438 shares outstanding, respectively) Additional Paid in Capital, Common Stock Additional paid-in capital Treasury Stock, Value Treasury stock, at average cost (4,794,161 and 4,899,349 shares, respectively) Retained earnings Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive income, net of taxes Equity, Attributable to Parent Ending balance Beginning balance Total stockholders' equity Liabilities and Equity Total liabilities and stockholders' equity Restricted Cash Restricted cash Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Excluding Accrued Interest Securities held-to-maturity, Allowance for Credit Losses Ending balance, Allowance of credit losses Beginning balance Securities held-to-maturity, allowance for credit losses Debt Securities, Held-to-Maturity, Restricted Securities held-to-maturity, assets pledged Debt Securities, Held-to-Maturity, Fair Value Securities held-to-maturity, fair value Debt Securities, Held-to-maturity, Fair Value, Total Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss Securities available for sale, amortized cost before allowance for credit losses Total Securities available for sale, Amortized Cost Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest Total Securities available for sale, Allowance for Credit Losses Ending balance, Allowance for credit losses Beginning balance Allowance for credit loss Securities available for sale, allowance for credit losses Debt Securities, Available-for-Sale, Restricted Securities available for sale, pledged as collateral Represents the fair value option for available-for-sale securities. Available For Sale Securities Fair Value Option Securities available for sale, fair value option Preferred Stock, Par or Stated Value Per Share Preferred stock, par value (in dollars per share) Preferred Stock, Shares Authorized Preferred stock, shares authorized (in shares) Preferred Stock, Shares Issued Preferred stock, shares issued (in shares) Common Stock, Par or Stated Value Per Share Common stock, par value (in dollars per share) Common Stock, Shares Authorized Common stock, shares authorized (in shares) Common Stock, Shares, Issued Common stock, shares issued (in shares) Common Stock, Shares, Outstanding Balance (in shares) Balance (in shares) Common stock, shares outstanding (in shares) Treasury Stock, Common, Shares Treasury stock, at average cost (in shares) Consolidated Statements of Operations Interest and Fee Income, Loans and Leases [Abstract] Interest and dividend income Interest and Fee Income, Loans and Leases Interest and fees on loans Interest and fees on loans Investment Income, Interest and Dividend [Abstract] Interest and dividends on securities: Investment Income, Interest Interest Investment Income, Dividend Dividends Other Interest and Dividend Income Other interest income Interest and Dividend Income, Operating Total interest and dividend income Interest Expense, Operating and Nonoperating [Abstract] Interest expense Interest Expense, Deposits Deposits Interest Expense, Other Other interest expense Interest Expense, Operating Total interest expense Interest Income (Expense), Operating Net interest income Provision for Loan, Lease, and Other Losses Provision (benefit) for credit losses Provision (benefit) for credit losses Interest Income (Expense), after Provision for Loan Loss Net interest income after provision (benefit) for credit losses Noninterest Income [Abstract] Non-interest income (loss) Revenue from Contract with Customer, Including Assessed Tax Banking services fee income Gain (Loss) on Sales of Loans, Net Net (gain) loss on sales of loans Net gain (loss) on sale of loans Fair Value, Option, Changes in Fair Value, Gain (Loss) Net loss (gain) from fair value adjustments Net gain (loss) from fair value adjustments Dividend income received on Federal Home Loan Bank Stock held by the entity. Federal Home Loan Bank of New York stock dividends The amount of gain (loss) from life insurance proceeds. Gain (Loss) From Life Insurance Proceeds Loss (gain) from life insurance proceeds Gain on life insurance proceeds Bank Owned Life Insurance Income Loss (income) from Bank owned life insurance Bank owned life insurance Noninterest Income, Other Operating Income Other income Noninterest Income Total non-interest income (loss) Noninterest Expense [Abstract] Non-interest expense Labor and Related Expense Salaries and employee benefits Occupancy, Net Occupancy and equipment Professional services Federal Deposit Insurance Corporation Premium Expense FDIC deposit insurance Information Technology and Data Processing Data processing Depreciation, Depletion and Amortization, Nonproduction Depreciation and amortization of premises and equipment Depreciation and amortization of bank premises and equipment The amount of income or expenses in related to other real estate owned or foreclosure. Income Expenses From Other Real Estate Owned Or Foreclosure Other real estate owned / foreclosure expense Goodwill, Impairment Loss Impairment of goodwill Other Noninterest Expense Other operating expenses Noninterest Expense Total non-interest expense Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income (loss) before income taxes Income Tax Expense (Benefit) Provision (benefit) for income taxes Provision (benefit) for income taxes Net income (loss) Net income (loss), as reported Earnings Per Share, Basic Basic earnings (loss) per common share Earnings Per Share, Diluted Diluted earnings (loss) per common share Diluted earnings (loss) per common share (in dollars per share) Consolidated Statements of Comprehensive Income Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent, Alternative [Abstract] Other comprehensive income (loss), net of tax: Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax Amortization of actuarial (gains) losses, net of taxes of ($4), and $23, respectively. OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax Change in net unrealized gains (losses) on securities available for sale, net of taxes of $2,225, and ($1,281), respectively. Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax Net unrealized gains (losses) on cashflow hedges, net of taxes of ($1,212) and $3,240, respectively. Other Comprehensive Income (Loss), Financial Liability, Fair Value Option, after Tax and Reclassification Adjustment, Attributable to Parent Change in fair value of liabilities related to instrument-specific credit risk, net of taxes of ($47), and ($2), respectively. Other Comprehensive Income (Loss), Net of Tax Other comprehensive income (loss) Other comprehensive income (loss), net of tax: Net current period other comprehensive income (loss), net of tax Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive net income (loss) Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, Tax Amortization of actuarial (gains) losses, taxes OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, Tax Net unrealized gains (losses) on securities, taxes Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax Net unrealized (losses) gains on cashflow hedges, taxes Other Comprehensive Income (Loss), Financial Liability, Fair Value Option, after Reclassification Adjustment, Tax Change in fair value of liabilities related to instrument-specific credit risk, taxes Consolidated Statement of Changes in Stockholders' Equity Equity Components [Axis] Equity Component [Domain] Common Stock [Member] Common Stock Additional Paid-in Capital [Member] Additional Paid-in Capital Treasury Stock, Common [Member] Treasury Stock Retained Earnings [Member] Retained Earnings AOCI Attributable to Parent [Member] Total Accumulated Other Comprehensive Income (Loss) Aggregate value of stock related to Restricted Stock Awards issued during the period. Stock Issued During the Period, Values, Restricted Stock Award, Gross Vesting of restricted stock unit awards Stock Issued During Period, Shares, Restricted Stock Award, Gross Vesting of restricted stock unit awards (in shares) APIC, Share-Based Payment Arrangement, Recognition and Exercise Stock-based compensation expense Share-Based Payment Arrangement, Decrease for Tax Withholding Obligation Repurchase of shares to satisfy tax obligation Share-Based Payment Arrangement, Shares Withheld for Tax Withholding Obligation Repurchase of shares to satisfy tax obligation (in shares) Dividends, Common Stock, Cash Dividends on common stock Common Stock, Dividends, Per Share, Cash Paid Dividends per common share (in dollars per share) Consolidated Statements of Cash Flows Net Cash Provided by (Used in) Operating Activities [Abstract] Operating Activities Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net income (loss) Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities: The periodic adjustments of the differences between securities' face values and purchase prices that are charged against earnings. Amortization of Premium, Net of Accretion of Discount Net amortization (accretion) of premiums and discounts Deferred Income Tax Expense (Benefit) Deferred income tax provision (benefit) For each line item in the statement of financial position, the amounts of gains and losses from fair value changes on qualifying hedges included in earnings. Fair Value Option Changes in Fair Value Gain Loss on Qualifying Hedges Net (gain) loss from fair value adjustments of hedges Share-Based Payment Arrangement, Noncash Expense Stock-based compensation expense Increase (Decrease) in Deferred Compensation Deferred compensation Amortization of Intangible Assets Amortization of core deposit intangibles Increase (Decrease) in Other Operating Assets (Increase) decrease in other assets Increase (Decrease) in Other Operating Liabilities (Decrease) increase in other liabilities Net Cash Provided by (Used in) Operating Activities Net cash provided by (used in) operating activities Net Cash Provided by (Used in) Investing Activities [Abstract] Investing Activities Payments to Acquire Property, Plant, and Equipment Purchases of premises and equipment Payments to Acquire Federal Home Loan Bank Stock Purchases of Federal Home Loan Bank New York stock Proceeds from Sale of Federal Home Loan Bank Stock Redemptions of Federal Home Loan Bank New York stock The cash inflow associated with the prepayments of debt securities designated as held-to-maturity. Proceeds from prepayments of securities held-to-maturity Payments to Acquire Debt Securities, Available-for-Sale Purchases of securities available for sale The cash inflow associated with sales and calls (requests of early payments) of debt and equity securities classified as available-for-sale securities. Proceeds from sales and calls of securities available for sale Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-Sale Proceeds from maturities and prepayments of securities available for sale Proceeds from Life Insurance Policy Proceeds from bank owned life insurance Amount of proceeds from the change in cash collateral. Proceeds From Change In Cash Collateral Change in cash collateral The net cash flow from repayments (origination) of loans. Net Repayments Originations Of Loans Net repayments (originations) of loans Payment for Acquisition, Loan, Held-for-Investment Purchases of loans Proceeds from sale of loans originally classified as held for investment Net Cash Provided by (Used in) Investing Activities Net cash provided by (used in) investing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Financing Activities Net Change Noninterest-Bearing Deposits, Domestic Net increase (decrease) in noninterest-bearing deposits Net Change Interest-Bearing Deposits, Domestic Net increase (decrease) in interest-bearing deposits The net increase/(decrease) in accumulated prepayments received by financial institutions from borrowers for taxes (for example, property taxes) and insurance (for example, property and catastrophe) which will periodically be remitted to the appropriate tax authority or insurer (or insurance agency) on behalf of the borrower. ffic_NetIncreaseDecreaseInAdvancePaymentsByBorrowersForTaxesAndInsurance1 Net increase (decrease) in mortgagors' escrow deposits Proceeds from (Repayments of) Short-Term Debt Net proceeds (repayments) from short-term borrowed funds Repayments of Long-Term Debt Repayment of long-term borrowings Payment, Tax Withholding, Share-Based Payment Arrangement Repurchase of shares to satisfy tax obligations Payments of Ordinary Dividends, Common Stock Cash dividends paid Net Cash Provided by (Used in) Financing Activities Net cash provided by (used in) financing activities Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Net increase (decrease) in cash and cash equivalents, and restricted cash Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents Cash, cash equivalents, and restricted cash, end of period Cash, cash equivalents, and restricted cash, beginning of period Supplemental Cash Flow Information [Abstract] Supplemental disclosure of cash flow information: Represents information pertaining to Cash payments. Cash Payment [Abstract] Cash payments for: