Deposits [Abstract] Deposits Time and Related Party Deposits [Text Block] The entire disclosure of time and related party deposits during the period. Condensed Financial Information Disclosure [Abstract] Condensed Income Statement [Table] Condensed Income Statement [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Parent [Member] Parent [Member] Condensed Income Statements, Captions [Line Items] Condensed Income Statements, Captions [Line Items] INCOME Interest and Dividend Income, Operating [Abstract] Interest income Interest Income, Operating EXPENSES Operating Expenses [Abstract] Interest expense Interest Expense Other operating expenses Operating Expenses (Loss) before equity in undistributed earnings of subsidiaries and income tax benefit Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Equity in undistributed earnings of subsidiaries Undistributed Earnings, Basic Income tax (benefit) expense Income Tax Expense (Benefit) Net income Net Income (Loss) Attributable to Parent Preferred stock dividend requirements Preferred Stock Dividends, Income Statement Impact Net income available to common stockholders Net Income (Loss) Available to Common Stockholders, Basic Risks and Uncertainties [Abstract] Concentration In Deposits Concentration In Deposits Disclosure [Text Block] The entire disclosure for concentrations in deposits existing at the date of the financial statements that make an entity vulnerable to a reasonably possible, near-term, severe impact. This disclosure informs financial statement users about the general nature of the risk associated with the concentration, and may indicate the percentage of concentration risk as of the balance sheet date. Receivables [Abstract] Schedule of Financing Receivable, Troubled Debt Restructurings [Table] Schedule of Financing Receivable, Troubled Debt Restructurings [Table] Credit Loss Status [Axis] Credit Loss Status [Axis] Credit Loss Status [Domain] Credit Loss Status [Domain] Purchased Credit Impaired Loans [Member] Financial Asset Acquired with Credit Deterioration [Member] Class of Financing Receivable, Type [Axis] Class of Financing Receivable, Type [Axis] Class of Financing Receivable, Type [Domain] Class of Financing Receivable, Type [Domain] Trouble Debt Restructuring [Member] Trouble Debt Restructuring [Member] Financing Receivable, Modifications [Line Items] Financing Receivable, Modifications [Line Items] Number of loan portfolio segments Number Of Loan Portfolio Segments Number Of Loan Portfolio Segments Troubled debt restructuring Financing Receivable, Modifications, Recorded Investment Nonaccrual restructured loans Financing Receivable, Recorded Investment, Nonaccrual Status Number of Contracts Financing Receivable, Modifications, Number of Contracts Number of loans modified as troubled debt restructurings with subsequent default Financing Receivable, Modifications, Subsequent Default, Number of Contracts Allowance for loan losses Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Allowance for Loan Losses Pre-approved unused lines of credit with related parties Line of Credit Facility, Remaining Borrowing Capacity Small Business Lending Fund [Abstract] Small Business Lending Fund Small Business Lending Fund Disclosure [Text Block] The entire disclosure of small business lending fund as of balance sheet date. Condensed Parent Information Condensed Financial Information of Parent Company Only Disclosure [Text Block] Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward] Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward] Accretable yield, beginning of period Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield Additions Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield, Additions Accretion income Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield, Accretion Reclassification from nonaccretable Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield, Reclassifications from Nonaccretable Difference Other changes, net Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield, Period Increase (Decrease) Accretable yield, end of period Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments, Gain (Loss) [Table] Derivative Instruments, Gain (Loss) [Table] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Interest Rate Swap [Member] Interest Rate Swap [Member] Hedging Designation [Axis] Hedging Designation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Designated as Hedging Instrument [Member] Designated as Hedging Instrument [Member] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Interest Income Amount of Gain (Loss) Recognized in Income Derivative, Gain (Loss) on Derivative, Net Goodwill and Intangible Assets Disclosure [Abstract] Goodwill Goodwill Earnings Per Share [Abstract] Earnings Per Share Earnings Per Share [Text Block] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] All Other Loans [Member] Receivables Other than Receivables Acquired with Deteriorated Credit Quality [Member] Receivables Other than Receivables Acquired with Deteriorated Credit Quality [Member] Financing Receivable Portfolio Segment [Axis] Financing Receivable Portfolio Segment [Axis] Financing Receivable Portfolio Segment [Domain] Financing Receivable Portfolio Segment [Domain] Commercial Real Estate [Member] Commercial Real Estate Portfolio Segment [Member] Consumer Real Estate [Member] Residential Portfolio Segment [Member] Construction and Land Development [Member] Construction Portfolio Segment [Member] Construction Portfolio Segment [Member] Commercial and Industrial [Member] Commercial Portfolio Segment [Member] Consumer and Other [Member] Consumer Portfolio Segment [Member] Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Total loans Loans and Leases Receivable, Net of Deferred Income Less: Allowance for loan losses Loans and Leases Receivable, Allowance Loans, net Loans and Leases Receivable, Net Amount Income Tax Disclosure [Abstract] Schedule of Components of Income Tax Expense (Benefit) Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Schedule of Effective Income Tax Rate Reconciliation Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule of Deferred Tax Assets and Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] 2019 Time Deposit Maturities, Next Twelve Months 2020 Time Deposit Maturities, Year Two 2021 Time Deposit Maturities, Year Three 2022 Time Deposit Maturities, Year Four 2023 Time Deposit Maturities, Year Five Thereafter Time Deposit Maturities, after Year Five Total Time Deposits Maturities, after Next Twelve Months Schedule of Finite-Lived Intangible Assets Schedule of Finite-Lived Intangible Assets [Table Text Block] Finite-lived Intangible Assets Amortization Expense Finite-lived Intangible Assets Amortization Expense [Table Text Block] Schedule of Finite-Lived Intangible Assets, Future Amortization Expense Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Current tax expense Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Federal Current Federal Tax Expense (Benefit) State Current State and Local Tax Expense (Benefit) Deferred tax expense (benefit) related to: Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Federal Deferred Federal Income Tax Expense (Benefit) State Deferred State and Local Income Tax Expense (Benefit) Change in tax rate Tax Cuts and Jobs Act of 2017, Change in Tax Rate, Income Tax Expense (Benefit) Tax Cuts and Jobs Act of 2017, Change in Tax Rate, Income Tax Expense (Benefit) Total income tax expense Defined Benefit Plan [Abstract] Number Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward] Nonvested, beginning balance (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross Vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares Forfeited/expired (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Number of Shares Nonvested, ending balance (in shares) Weighted Average Grant-Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Weighted Average Grant-Date Fair Value, Nonvested, beginning balance (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Option, Nonvested, Weighted Average Exercise Price Weighted Average Grant-Date Fair Value, Granted (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Weighted Average Grant-Date Fair Value, Vested (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Weighted Average Grant Date Fair Value Weighted Average Grant-Date Fair Value, Forfeited/expired (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested Options Forfeited, Weighted Average Grant Date Fair Value Weighted Average Grant-Date Fair Value, Nonvested, ending balance (in dollars per share) Goodwill and Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Commitments and Contingencies Disclosure [Abstract] Commitments to extend credit Unused Commitments to Extend Credit Standby letters of credit Outstanding Off balance Sheet Risks Amount Liability Contractual amount for all off-balance sheet commitments. Investments, Debt and Equity Securities [Abstract] Proceeds Proceeds from Sale of Debt Securities, Available-for-sale Gains realized Debt Securities, Available-for-sale, Realized Gain Losses realized Debt Securities, Available-for-sale, Realized Loss Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statement [Table] Condensed Balance Sheet Statements, Captions [Line Items] Condensed Balance Sheet Statements, Captions [Line Items] ASSETS Assets [Abstract] Cash Cash and Cash Equivalents, at Carrying Value Investment in subsidiaries Equity Method Investments Other assets Other Assets Total assets Assets LIABILITIES AND STOCKHOLDERS’ EQUITY Liabilities and Equity [Abstract] Other liabilities Other Liabilities, Current Other borrowings Other Borrowings Total liabilities Liabilities Stockholders’ equity Stockholders' Equity Attributable to Parent Total liabilities and stockholders' equity Liabilities and Equity Statement of Comprehensive Income [Abstract] Unrealized holding losses arising during the year, tax expense (benefit) Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax Reclassification adjustment for gains included in net income, tax expense Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax Accounting Policies [Abstract] Schedule of Useful Lives Property, Plant and Equipment [Table Text Block] Debt Disclosure [Abstract] Subordinated debt Debt Disclosure [Text Block] Property, Plant and Equipment [Abstract] Land and land improvements Land Building and leasehold improvements Buildings and Improvements, Gross Furniture, fixtures and equipment Furniture and Fixtures, Gross Construction in progress Construction in Progress, Gross Total, gross Property, Plant and Equipment, Gross Accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Total, net Property, Plant and Equipment, Net Banking and Thrift [Abstract] Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block] Business Combinations [Abstract] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Foothills Bancorp [Member] Foothills Bancorp [Member] Foothills Bancorp [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Shares of SMBK common stock issued (in shares) Business Acquisition, Equity Interest Issued or Issuable, Number of Shares Market price of SMBK common stock (in dollars per share) Business Acquisition, Share Price Estimated fair value of SMBK common stock issued Business Combination, Consideration Transferred, Equity Interests Issued and Issuable Cash consideration paid Payments to Acquire Businesses, Gross Total consideration Business Combination, Consideration Transferred Fair value of assets acquired and liabilities assumed: Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract] Cash and cash equivalents Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents Investment securities available for sale Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Marketable Securities Restricted investments Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Investment Owned Restricted Cost Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Investment Owned Restricted Cost Loans Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables Premises and equipment Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment Core deposit intangible Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Core Deposit Intangible The amount of Assets Acquired and Liabilities Assumed Core Deposit Intangible. Prepaid and other assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets Deposits Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Deposits Liability The amount of assets acquired and liabilities assumed deposits liability. FHLB advances and other borrowings Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt Payables and other liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable Total fair value of net assets acquired Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Goodwill Schedule of Financing Receivables Past Due [Table] Schedule of Financing Receivables Past Due [Table] Financing Receivables, Period Past Due [Axis] Financing Receivables, Period Past Due [Axis] Financing Receivables, Period Past Due [Domain] Financing Receivables, Period Past Due [Domain] 30 to 59 Days Past Due and Accruing [Member] Financing Receivables, 30 to 59 Days Past Due [Member] 60 to 89 Days Past Due and Accruing [Member] Financing Receivables, 60 to 89 Days Past Due [Member] Past Due 90 Days or More and Accruing [Member] Financing Receivables, Equal to Greater than 90 Days Past Due [Member] Financing Receivable, Recorded Investment, Past Due [Line Items] Financing Receivable, Recorded Investment, Past Due [Line Items] Recorded investment, past due Financing Receivable, Recorded Investment, Past Due Nonaccrual Total Past Due Financing Receivable, Recorded Investment, Past Due Including Nonaccrual Status Financing receivable recorded investment past due including non accrual status. Current Loans Financing Receivable, Recorded Investment, Current Securities Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Weighted Average [Member] Weighted Average [Member] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Pro Forma [Member] Pro Forma [Member] Entegra Financial Corp [Member] Entegra Financial Corp [Member] Entegra Financial Corp [Member] Tennessee Bancshares [Member] Tennessee Bancshares [Member] Tennessee Bancshares [Member] Capstone Bancshares Inc. [Member] Capstone Bancshares Inc. [Member] Capstone Bancshares Inc. [Member] Atlantic Capital Bank, N.A. [Member] Atlantic Capital Bank, N.A. [Member] Atlantic Capital Bank, N.A. [Member] Shares issued upon conversion (in shares) Business Combination, Shares Issued Upon Conversion Business Combination, Shares Issued Upon Conversion Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Cash paid upon conversion (in dollars per share) Business Combination, Cash Paid Upon Conversion Business Combination, Cash Paid Upon Conversion Number of shares issued (in shares) Cash paid for merger Business Combination, Cash Paid For Merger Business Combination, Cash Paid For Merger Additional consideration transferred Business Combination, Additional Consideration Transferred Business Combination, Additional Consideration Transferred Consecutive trading days Business Acquisition, Consecutive Trading Days Business Acquisition, Consecutive Trading Days Share price (in dollars per share) Ownership interest (as a percent) Business Acquisition, Percentage of Voting Interests Acquired Pro forma, revenue of acquiree since acquisition date, actual Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual Pro forma information, earnings (loss) since acquisition date, actual Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual Pro forma revenue Business Acquisition, Pro Forma Revenue Pro forma net income (loss) Business Acquisition, Pro Forma Net Income (Loss) Operating expenses Exchange of shares (in shares) Business Combination Exchange of Shares Business combination exchange of shares. Cash payment per share (in dollars per share) Business Combination, Consideration Transferred, Equity Interests Issued Or Issuable, Price Per Share Business Combination, Consideration Transferred, Equity Interests Issued or Issuable, Price per Share Percentage of common stock consideration transferred Business Combination, Consideration Transferred, Equity Interests Issued Or Issuable, Percent Business Combination, Consideration Transferred, Equity Interests Issued or Issuable, Percent Percentage of cash consideration transferred Business Combination, Consideration Transferred, Payments To Acquire Business, Percent Business Combination, Consideration Transferred, Payments to Acquire Business, Percent Goodwill adjustment Goodwill, Purchase Accounting Adjustments Fair value adjustment Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Fair Value Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Fair Value Debt Securities, Available-for-sale [Table] Debt Securities, Available-for-sale [Table] Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] U.S. Government-sponsored enterprises (GSEs) [Member] US Government-sponsored Enterprises Debt Securities [Member] Muncipal Securities [Member] Muncipal Securities [Member] Other Debt Securities [Member] Other Debt Obligations [Member] Mortgage Backed Securities [Member] Residential Mortgage Backed Securities [Member] Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] Debt securities available-for-sale: Marketable Securities [Abstract] Less than 12 Months, Fair Value Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months Less than 12 Months, Gross Unrealized Losses Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss 12 Months or Greater, Fair Value Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer 12 Months or Greater, Gross Unrealized Losses Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Total, Fair Value Debt Securities, Available-for-sale, Unrealized Loss Position Total, Gross Unrealized Losses Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss Federal income tax expense computed at the statutory rate Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount State income taxes, net of federal tax benefit Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount Nondeductible acquisition expenses Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Amount Tax benefit from stock options Effective Income Tax Rate Reconciliation, Deduction, Amount Change in tax rate Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount Other Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Deferred Bonus and Profit Sharing Arrangements, Individual Contracts, Type of Deferred Compensation [Axis] Deferred Bonus and Profit Sharing Arrangements, Individual Contracts, Type of Deferred Compensation [Axis] Deferred Bonus and Profit Sharing Arrangement, Individual Contract, Type of Deferred Compensation [Domain] Deferred Bonus and Profit Sharing Arrangement, Individual Contract, Type of Deferred Compensation [Domain] Officer and Employee Plans [Member] Officer and Employee Plans [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Number Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Outstanding (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures Exercised (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period Capstone options assumed in business combination (in shares) Share based Compensation Arrangement by Share based Payment Award Options Retained By In Merger It represents the share based compensation arrangement by share based payment award options retained by In merger. Outstanding (in shares) Weighted Average Exercisable Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Weighted Average Exercisable Price, Outstanding (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Weighted Average Exercisable Price Granted (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Weighted Average Exercisable Price Exercised (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Weighted Average Exercisable Price Forfeited (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price Weighted Average Exercisable Price, Capstone options assumed in business combination (in dollars per share) Share based Compensation Arrangements by Share based Payment Award Options Retained By In Merger Weighted Average Exercise Price It represents the share based compensation arrangements by share based payment award options retained by in merger weighted average exercise price. Weighted Average Exercise Price, Outstanding (in dollars per share) Schedule of Available-for-sale Securities Reconciliation Schedule of Available-for-sale Securities Reconciliation [Table Text Block] Investments Classified by Contractual Maturity Date Investments Classified by Contractual Maturity Date [Table Text Block] Schedule of Unrealized Loss on Investments Schedule of Unrealized Loss on Investments [Table Text Block] Schedule of Realized Gain (Loss) on Available-for-sale Securities Schedule of Realized Gain (Loss) [Table Text Block] Mortgage-backed securities [Member] Securities in unrealized loss positions (Number of investments) Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions Available-for-sale securities pledged as collateral Debt Securities, Available-for-sale, Restricted Other real estate owned Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Other Real Estate Owned The amount of assets acquired and liabilities assumed other real estate owned. Accounting Policies [Table] Accounting Policies [Table] Scenario, Forecast [Member] Scenario, Forecast [Member] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2016-02 [Member] Accounting Standards Update 2016-02 [Member] Minimum [Member] Minimum [Member] Maximum [Member] Maximum [Member] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Building and Leasehold Improvements [Member] Building and Building Improvements [Member] Furniture and Equipment [Member] Furniture and Fixtures [Member] Collateral [Axis] Collateral [Axis] Collateral [Domain] Collateral [Domain] Residential Real Estate [Member] Residential Real Estate [Member] Accounting Policies [Line Items] Accounting Policies [Line Items] Federal Reserve Bank, reserve requirement Federal Reserve Bank Reserve Requirement Amount of cash or deposit reserve required to be maintained with federal reserve bank. Foreclosed assets Repossessed Assets Mortgage loans in process of foreclosure Mortgage Loans in Process of Foreclosure, Amount Useful life Property, Plant and Equipment, Useful Life Amortization of intangible assets Amortization of Intangible Assets Impairment of intangible assets Impairment of Intangible Assets, Finite-lived Gross interchange and debit card transaction fees Fees And Commissions, Debit Cards, Gross Fees And Commissions, Debit Cards, Gross Network costs Fees And Commissions, Network Costs Fees And Commissions, Network Costs Interchange and debit card transaction fees Fees And Commissions, Debit Cards1 Fees And Commissions, Debit Cards1 Advertising expense Advertising Expense Number of reportable segments Number of Reportable Segments Right-of-use assets Operating Lease, Right-of-Use Asset Lease liability Operating Lease, Liability Business Combinations Business Combination Disclosure [Text Block] Condensed Balance Sheet Condensed Balance Sheet [Table Text Block] Condensed Income Statement Condensed Income Statement [Table Text Block] Condensed Cash Flow Statement Condensed Cash Flow Statement [Table Text Block] Amortized Cost Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, Amortized Cost, Rolling Maturity [Abstract] Due in one year or less Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, within One Year, Amortized Cost Due from one year to five years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Amortized Cost Due from five years to ten years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Amortized Cost Due after ten years Debt Securities, Available-for-sale, Allocated and Single Maturity Date, Maturity, after 10 Years, Amortized Cost Amortized Cost Debt Securities, Available-for-sale, Maturity, without Single Maturity Date, Amortized Cost Total Debt Securities, Available-for-sale, Amortized Cost Fair Value Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Fair Value [Abstract] Due in one year or less Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, within One Year, Fair Value Due from one year to five years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Fair Value Due from five years to ten years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Fair Value Due after ten years Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, after 10 Years, Fair Value Fair Value Debt Securities, Available-for-sale, Maturity, without Single Maturity Date, Fair Value Total Debt Securities, Available-for-sale Statement of Cash Flows [Abstract] CASH FLOWS FROM OPERATING ACTIVITIES Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Net income Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation, amortization, and accretion Depreciation, Depletion and Amortization, Nonproduction Provision for loan losses Provision for Loan and Lease Losses Stock compensation expense Share-based Compensation Gains from redemption and sale of securities available-for-sale Debt Securities, Available-for-sale, Realized Gain (Loss) Deferred income tax expense Deferred Income Tax Expense (Benefit) Income on bank owned life insurance, net Bank Owned Life Insurance Income Loss on disposal of fixed assets Gain (Loss) on Disposition of Property Plant Equipment Net gains from sale of loans and other assets Other Gains And Losses Of Asset Net The net other (gain) losses resulting from a sale of other assets , loans, including adjustments to record loans classified as held-for-sale at the lower-of-cost-or-market and fair value adjustments to loan held for investment purposes. Net losses from sale of foreclosed assets Gains (Losses) on Sales of Other Real Estate Loans originated for sale Payments for Origination and Purchases of Loans Held-for-sale Proceeds from sale of loans originated for sale Proceeds from Sale of Mortgage Loans Held-for-sale Changes in other assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Accrued interest receivable Increase (Decrease) in Accrued Interest Receivable, Net Accrued interest payable Increase (Decrease) in Interest Payable, Net Other assets and liabilities Increase (Decrease) in Other Operating Assets and Liabilities, Net Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities CASH FLOWS FROM INVESTING ACTIVITIES Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Purchase of securities available-for-sale Payments to Acquire Debt Securities, Available-for-sale Proceeds from sales, maturities, and paydowns of securities available-for-sale Proceeds from Sale and Maturity of Debt Securities, Available-for-sale (Purchase) redemption of restricted investments Payments to Acquire Restricted Investments (Purchase) redemption of restricted investments Proceeds from Sale of Restricted Investments Purchase of bank owned life insurance Payment to Acquire Life Insurance Policy, Investing Activities Loan originations and principal collections, net Payments for (Proceeds from) Loans Receivable Purchase of bank premises and equipment Payments to Acquire Property, Plant, and Equipment Proceeds from sale of foreclosed assets Proceeds from Sale of Foreclosed Assets Net cash and cash equivalents paid (received) in business combinations Payments to Acquire Business Two, Net of Cash Acquired Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities CASH FLOWS FROM FINANCING ACTIVITIES Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Net increase in deposits Increase (Decrease) in Deposits Net decrease in securities sold under agreements to repurchase Increase (Decrease) in Federal Funds Purchased and Securities Sold under Agreements to Repurchase, Net Issuance of common stock Proceeds from Issuance of Common Stock Payment of dividends on preferred stock Payments of Ordinary Dividends, Preferred Stock and Preference Stock Redemption of preferred stock Payments for Repurchase of Redeemable Preferred Stock Net proceeds from subordinated debt Proceeds from Issuance of Subordinated Long-term Debt Repayment of Federal Home Loan Bank advances and other borrowings Net Payments On Federal Home Loan Bank Advances The net cash outflow associated with Federal Home Loan Bank Advances made during the period. Proceeds from Federal Home Loan Bank advances and other borrowings Proceeds from (Payments for) Other Financing Activities Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities NET INCREASE IN CASH AND CASH EQUIVALENTS Cash and Cash Equivalents, Period Increase (Decrease) CASH AND CASH EQUIVALENTS, beginning of year CASH AND CASH EQUIVALENTS, end of year SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION Supplemental Cash Flow Information [Abstract] Cash paid during the period for interest Interest Paid, Excluding Capitalized Interest, Operating Activities Cash paid during the period for income taxes Income Taxes Paid NONCASH INVESTING AND FINANCING ACTIVITIES Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Change in unrealized losses on securities available-for-sale Noncash Investing And Financing Activities Change In Unrealized Gains On Securities Available For Sale The change in unrealized holding gain (loss), net of tax, on available-for-sale securities included in a separate component of shareholders' equity noncash investing or financing activities. Acquisition of real estate through foreclosure SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Acquisition Through Foreclosure Transfer from Bank premises to foreclosed assets Real Estate Owned, Transfer to Real Estate Owned Change in goodwill due to acquisitions Goodwill, Acquired During Period Financed sales of foreclosed assets Financed Sales Of Foreclosed Assets Represents the amount of financed sales of foreclosed assets in non-cash investing and financing activities. Statement of Financial Position [Abstract] Allowance for loan losses (in dollars) Preferred Stock, Par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Preferred stock, shares issued (in shares) Preferred Stock, Shares Issued Preferred stock, shares outstanding (in shares) Preferred Stock, Shares Outstanding Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock, shares authorized (in shares) Common Stock, Shares Authorized Common stock, shares issued (in shares) Common Stock, Shares, Issued Securities Sold Under Agreement to Repurchase [Abstract] Securities Sold Under Agreements to Repurchase Repurchase Agreements, Resale Agreements, Securities Borrowed, and Securities Loaned Disclosure [Text Block] 2019 Operating Leases, Future Minimum Payments Due, Next Twelve Months 2020 Operating Leases, Future Minimum Payments, Due in Two Years 2021 Operating Leases, Future Minimum Payments, Due in Three Years 2022 Operating Leases, Future Minimum Payments, Due in Four Years 2023 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Total Operating Leases, Future Minimum Payments Due Fair Value Disclosures [Abstract] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] Carrying Amount [Member] Reported Value Measurement [Member] Estimated Fair Value [Member] Estimate of Fair Value Measurement [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Assets: Cash and cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Securities available-for-sale Restricted investments Investment Owned, Restricted, Cost Loans, net Loans Receivable, Fair Value Disclosure Liabilities: Liabilities [Abstract] Noninterest-bearing demand deposits Noninterest-bearing Deposit Liabilities Interest-bearing demand deposits Demand Deposit Accounts Money Market and Savings deposits Deposits, Savings Deposits Time deposits Time Deposits Fair Value Representing time deposits fair value. Securities sold under agreements to repurchase Federal Funds Purchased and Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure Federal Home Loan Bank advances and other borrowings Federal Home Loan Bank Advances and Other Borrowings The aggregate carrying amount of all Federal Home Loan Bank loans (advances) and also includes other borrowings. Subordinated debt Subordinated Debt Derivative financial instruments Derivative Liability Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table] Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table] Exercise Price Range [Axis] Exercise Price Range [Axis] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Domain] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Domain] 6.60 [Member] Exercise Price One [Member] 6.80 [Member] Exercise Price Two [Member] 9.48 [Member] Exercise Price Three [Member] 9.60 [Member] Exercise Price Four [Member] 11.76 [Member] Exercise Price Six [Member] 14.40 [Member] Exercise Price Seven [Member] 15.05 [Member] Exercise Price Eight [Member] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] Exercise Prices (in dollars per share) Number Outstanding (in shares) Options Outstanding, Weighted Average Remaining Life Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term Options Outstanding, Weighted Average Exercise Price (in dollars per share) Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price Options, Number Exercisable (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Options Exercisable, Weighted Average Exercise Price (in dollars per share) Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price Condensed Cash Flow Statement [Table] Condensed Cash Flow Statement [Table] Condensed Cash Flow Statements, Captions [Line Items] Condensed Cash Flow Statements, Captions [Line Items] Net income Adjustments to reconcile net income to net cash (used in) provided by operating activities: Equity in undistributed income of subsidiary Equity In Undistributed Income Of Subsidiary The income that is allocated to common stock and participating securities to the extent that each security may share in earnings as if all of the income for the period had been distributed. Other Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations CASH FLOWS FROM FINANCING ACTIVITIES Proceeds from issuance of note payable Proceeds from Notes Payable Repayment of note payable Repayments of Notes Payable Proceeds from issuance of common stock Payment of dividends on preferred stock Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations CASH FLOWS FROM INVESTING ACTIVITIES Net cash paid for business combinations Payments to Acquire Businesses and Interest in Affiliates Equity contribution to subsidiary Payments of Distributions to Affiliates Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations Allowance for Loan and Lease Losses [Roll Forward] Allowance for Loan and Lease Losses [Roll Forward] Beginning balance Loans charged off Allowance for Loan and Lease Losses, Write-offs Recoveries of loans charged off Allowance for Loan and Lease Loss, Recovery of Bad Debts Provision (reallocation) charged to operating expense Ending balance Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Table] Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Table] Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items] Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items] Certain Loans Acquired In Transfer Not Accounted Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Outstanding Balance Less remaining purchase discount Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Purchase Discount This relates to loans not accounted for as debt securities, with evidence for the purchase discount and which loans are not transferred. Total, gross Certain Loans Acquired In Transfer Not Accounted For As Debt Securities Net Of Purchase Discount This relates to loans not accounted for as debt securities, with evidence for the net of purchase which is acquired in the transfer of certain loans. Less: Allowance for loan losses Carrying amount, net of allowance Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Carrying Amount, Net Schedule of Business Acquisitions Schedule of Business Acquisitions, by Acquisition [Table Text Block] Scheduled Maturities Of Time Deposit Scheduled Maturities Of Time Deposit [Table Text Block] Tabular disclosure of the scheduled maturities of time deposits during the period. Schedule of Impaired Financing Receivable [Table] Schedule of Impaired Financing Receivable [Table] Financing Receivable, Impaired [Line Items] Financing Receivable, Impaired [Line Items] Impaired loans without a valuation allowance, Recorded Investment Impaired Financing Receivable, with No Related Allowance, Recorded Investment Impaired loans without a valuation allowance, Unpaid Principal Balance Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance Impaired loans without a valuation allowance, Average Recorded Investment Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment Impaired loans without a valuation allowance, Interest Income Recognized Impaired Financing Receivable, with No Related Allowance, Interest Income, Cash Basis Method Impaired loans with a valuation allowance, Recorded Investment Impaired Financing Receivable, with Related Allowance, Recorded Investment Impaired loans with a valuation allowance, Unpaid Principal Balance Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance Impaired loans with a valuation allowance, Related Allowance Impaired Financing Receivable, Related Allowance Impaired loans with a valuation allowance, Average Recorded Investment Impaired Financing Receivable, with Related Allowance, Average Recorded Investment Impaired loans with a valuation allowance, Interest Income Recognized Impaired Financing Receivable, with Related Allowance, Interest Income, Cash Basis Method Total impaired loans, Recorded Investment Impaired Financing Receivable, Recorded Investment Total impaired loans, Unpaid Principal Balance Impaired Financing Receivable, Unpaid Principal Balance Total impaired loans, Average Recorded Investment Impaired Financing Receivable, Average Recorded Investment Total impaired loans, Interest Income Recognized Impaired Financing Receivable, Interest Income, Cash Basis Method Schedule of Federal Home Loan Bank Advances, by Branch of FHLB Bank [Table] Schedule of Federal Home Loan Bank Advances, by Branch of FHLB Bank [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Loans Payable [Member] Loans Payable [Member] Consolidated Entities [Axis] Consolidated Entities [Axis] Consolidated Entities [Domain] Consolidated Entities [Domain] Subsidiaries [Member] Subsidiaries [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Revolving Credit Facility [Member] Revolving Credit Facility [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Prime Rate [Member] Prime Rate [Member] Short-term Debt, Type [Axis] Short-term Debt, Type [Axis] Short-term Debt, Type [Domain] Short-term Debt, Type [Domain] Federal Home Loan Bank Advances [Member] Federal Home Loan Bank Advances [Member] Period [Axis] Period [Axis] Period [Domain] Period [Domain] Fiscal quarter 2019 [Member] Fiscal quarter 2019 [Member] Fiscal quarter 2020 [Member] Fiscal quarter 2020 [Member] Fiscal Quarter 2021 [Member] Fiscal Quarter 2021 [Member] Fiscal Quarter 2021 [Member] Fiscal Quarter 2022 [Member] Fiscal Quarter 2022 [Member] Fiscal Quarter 2022 [Member] Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items] Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items] Line of credit facility, maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Long-term line of credit Long-term Line of Credit Basis spread on variable rate (as a percent) Debt Instrument, Basis Spread on Variable Rate Variable rate, floor (as a percent) Line of Credit Facility, Variable Rate, Floor, Percentage Line of Credit Facility, Variable Rate, Floor, Percentage Initial line of credit period Line of Credit Facility, Initial Period Line of Credit Facility, Initial Period Amortization Amortization Covenant compliance, ratio of non-performing assets as a percentage total assets, not to be greater than Debt Instrument, Covenant Terms, Ratio of Non-performing Assets as a Percentage Total Assets Debt Instrument, Covenant Terms, Ratio of Non-performing Assets to Total Assets Covenant compliance, Texas ratio, not to be greater than (as a percent) Debt Instrument, Covenant Terms, Texas Ratio, Non-performing Assets as a Percentage of Tangible Equity and Allowance for Loan and Lease Losses Debt Instrument, Covenant Terms, Texas Ratio, Non-performing Assets as a Percentage of Tangible Equity and Allowance for Loan and Lease Losses Covenant compliance, liquidity ratio, not to be less than (as a percent) Debt Instrument, Covenant Terms, Liquidity Ratio, Percent Debt Instrument, Covenant Terms, Liquidity Ratio, Percent Covenant compliance, liquidity ratio in consecutive quarters, not to be less than (as a percent) Debt Instrument, Covenant Terms, Liquidity Ratio in Consecutive Quarters, Percent Debt Instrument, Covenant Terms, Liquidity Ratio in Consecutive Quarters, Percent Covenant terms, return on average assets, next nine months (as a percent) Debt Instrument, Covenant Terms, Return on Average Assets, Next Nine Months, Percent Debt Instrument, Covenant Terms, Return on Average Assets, Next Nine Months, Percent Covenant terms, return on average assets, thereafter (as a percent) Debt Instrument, Covenant Terms, Return on Average Assets, Thereafter, Percent Debt Instrument, Covenant Terms, Return on Average Assets, Thereafter, Percent Total risk-based capital ratio required to well-capitalized Capital Required to be Well Capitalized to Risk Weighted Assets Tier 1 risk-based capital ratio required to be well capitalized Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets Tier 1 leverage ratio required to be well capitalized Tier One Leverage Capital Required to be Well Capitalized to Average Assets Covenant terms, debt service coverage ratio Debt Instrument, Covenant Terms, Debt Service Coverage Ratio, Percent Debt Instrument, Covenant Terms, Debt Service Coverage Ratio, Percent Covenant compliance, interest coverage ratio, not to be less than Debt Instrument, Covenant Terms, Interest Coverage Ratio Debt Instrument, Covenant Terms, Interest Coverage Ratio Interest rate at period end (as a percent) Line of Credit Facility, Interest Rate at Period End Carrying value of securities pledged to Federal Home Loan Bank Carrying Value Of Securities Pledged To Federal Home Loan Bank Represents carrying value of securities pledged to federal home loan bank during the reporting period. Long-term federal home loan bank advances Long-term Federal Home Loan Bank Advances Principal amount Debt Instrument, Face Amount Interest rate Debt Instrument, Interest Rate, Stated Percentage Loan term Debt Instrument, Term Federal funds purchased Federal Funds Purchased Schedule of Financing Receivable, Recorded Investment, Credit Quality Indicator [Table] Schedule of Financing Receivable, Recorded Investment, Credit Quality Indicator [Table] Internal Credit Assessment [Axis] Internal Credit Assessment [Axis] Internal Credit Assessment [Domain] Internal Credit Assessment [Domain] Pass [Member] Pass [Member] Watch [Member] Watch [Member] Special Mention [Member] Special Mention [Member] Substandard [Member] Substandard [Member] Doubtful [Member] Doubtful [Member] Financing Receivable, Recorded Investment [Line Items] Financing Receivable, Recorded Investment [Line Items] Shares of SMBK common stock issued to Capstone shareholders as of November 1, 2017 (in shares) Business Combination Common Stock Shares Outstanding Value Purchase price of common stock shares outstanding value. Estimated fair value of Capstone stock options Business Combination, Consideration Transferred, Other Premises and equipment Bank owned life insurance Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Bank Owned Life Insurance The amount of assets acquired and liabilities assumed bank owned life insurance. Loans and Leases Receivable, Related Parties [Roll Forward] Loans and Leases Receivable, Related Parties [Roll Forward] Balance, beginning of year Loans and Leases Receivable, Related Parties Disbursements Loans and Leases Receivable, Related Parties, Additions Repayments Loans and Leases Receivable, Related Parties, Proceeds Balance, end of year Impaired loans Impaired Loans Fair Value Disclosure Representing impaired loans fair value disclosure. Foreclosed assets Foreclosed Assets Fair Value Representing foreclosed assets fair value. Loans and Allowance for Loan Losses Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Other comprehensive income (loss), net of tax: Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Unrealized holding gains (losses) arising during the year, net of tax (benefit) expense of $(514,287) and $55,405 in 2018 and 2017, respectively Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax Reclassification adjustment for gains included in net income, net of tax expense of $280 and $54,533 in 2018 and 2017, respectively Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax Total other comprehensive loss Other Comprehensive Income (Loss), Net of Tax Effect of tax rate change on unrealized gains (losses) on available-for-sale securities Tax Cuts and Jobs Act of 2017, Other Comprehensive Income (Loss), Reclassification from AOCI to Retained Earnings, Tax Effect Tax Cuts and Jobs Act of 2017, Other Comprehensive Income (Loss), Reclassification from AOCI to Retained Earnings, Tax Effect Total other comprehensive loss Other Comprehensive Income (Loss), Net of Tax and Adjustments Other Comprehensive Income (Loss), Net of Tax and Adjustments Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Carrying amount of hedged asset Hedged Asset, Fair Value Hedge Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Assets Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease) Anti-dilutive securities excluded from computation of earnings per share (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Basic earnings per share computation: Earnings Per Share, Basic [Abstract] Net income available to common stockholders Average common shares outstanding - basic (in shares) Weighted Average Number of Shares Outstanding, Basic Basic earnings per share (in dollars per share) Earnings Per Share, Basic Diluted earnings per share computation: Earnings Per Share, Diluted [Abstract] Net income available to common stockholders Net Income (Loss) Available to Common Stockholders, Diluted Average common shares outstanding - basic (in shares) Weighted Average Number Of Shares Outstanding Basic 1 Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period. Incremental shares from assumed conversions: Dilutive Securities, Effect on Basic Earnings Per Share [Abstract] Stock options (in shares) Weighted Average Number Diluted Shares Outstanding Adjustment Average common shares outstanding - diluted (in shares) Weighted Average Number of Shares Outstanding, Basic and Diluted Diluted earnings per share (in dollars per share) Earnings Per Share, Diluted Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Interest Rate Swap, Liability [Member] Interest Rate Swap, Liability [Member] Interest Rate Swap, Liability [Member] Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Weighted average remaining maturity Derivative, Average Remaining Maturity Weighted Average Pay Rate Derivative, Average Variable Interest Rate Derivative liability, notional amount Derivative Liability, Notional Amount Hedged liability, fair value Hedged Liability, Fair Value Hedge Concentration Risk [Table] Concentration Risk [Table] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Customer Concentration Risk [Member] Customer Concentration Risk [Member] Concentration Risk [Line Items] Concentration Risk [Line Items] Deposits Deposits Deferred tax assets: Deferred Tax Assets, Net [Abstract] Allowance for loan losses Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Provision for Loan Losses Fair value adjustments Deferred Tax Assets Fair Value Adjustments Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences on fair value adjustments. Unrealized losses on investment securities Deferred Tax Assets, Unrealized Losses on Available-for-Sale Securities, Gross Unrealized losses on hedges Deferred Tax Assets, Hedging Transactions Foreclosed real estate Deferred Tax Assets Fore Closed Asset Amount before allocation of valuation allowances of deferred tax assets attributable to deductible temporary differences from foreclosed assets. Deferred compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits Federal net operating loss carryforward Deferred Tax Assets, Operating Loss Carryforwards, Domestic Other Deferred Tax Assets, Other Total deferred tax assets Deferred Tax Assets, Gross Deferred tax liabilities: Deferred Tax Liabilities, Net [Abstract] Accumulated depreciation Deferred Tax Liabilities Depreciation Represents deferred tax liabilities depreciation as on the reporting period. Core deposit intangible Deferred Tax Liabilities, Intangible Assets Other Deferred Tax Liabilities, Other Total deferred tax liabilities Deferred Tax Liabilities, Net Net deferred tax asset Deferred Tax Assets, Net Schedule of Assets Sold under Agreements to Repurchase [Table] Schedule of Assets Sold under Agreements to Repurchase [Table] Agency Securities [Member] Agency Securities [Member] Assets Sold under Agreements to Repurchase [Line Items] Assets Sold under Agreements to Repurchase [Line Items] Securities sold under agreement to repurchase, maturity of agreement Securities Sold Under Agreement to Repurchase, Maturity of Agreement Securities Sold Under Agreement to Repurchase, Maturity of Agreement Securities sold under agreements to repurchase Securities Sold under Agreements to Repurchase Collateral Securities Sold under Agreements to Repurchase, Fair Value of Collateral Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Preferred Stock [Member] Preferred Stock [Member] Common Stock [Member] Common Stock [Member] Additional Paid-in Capital [Member] Additional Paid-in Capital [Member] Retained Earnings [Member] Retained Earnings [Member] Accumulated Other Comprehensive Loss [Member] AOCI Attributable to Parent [Member] Statement [Line Items] Statement [Line Items] BALANCE Other comprehensive gain (loss) Reclassification adjustment for tax rate change Tax Cuts And Jobs Act Of 2017, Reclassification From AOCI To Retained Earnings, Tax Effect Tax Cuts and Jobs Act of 2017, Reclassification from AOCI to Retained Earnings, Tax Effect Issuance of common stock Stock Issued During Period, Value, New Issues Issuance of stock grants and restricted stock Stock Granted, Value, Share-based Compensation, Gross Shares issued to shareholders Stock Issued During Period, Value, Acquisitions Redemption of preferred stock Stock Redeemed or Called During Period, Value Exercise of stock options Stock Issued, Value, Stock Options Exercised, Net of Tax Benefit (Expense) Dividends on preferred stock Dividends, Preferred Stock Stock compensation expense Adjustments to Additional Paid in Capital, Share-based Compensation, Stock Options, Requisite Service Period Recognition BALANCE Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Vesting [Axis] Vesting [Axis] Vesting [Domain] Vesting [Domain] Share-based Compensation Award, Tranche Three [Member] Share-based Compensation Award, Tranche Three [Member] Share-based Compensation Award, Tranche Two [Member] Share-based Compensation Award, Tranche Two [Member] Share-based Compensation Award, Tranche One [Member] Share-based Compensation Award, Tranche One [Member] Defined Contribution Plan Matching Range [Axis] Defined Contribution Plan Matching Range [Axis] Defined Contribution Plan Matching Range [Axis] Deferred Contribution Plan Matching Range [Domain] Defined Contribution Plan Matching Range [Domain] [Domain] for Defined Contribution Plan Matching Range [Axis] 401 (k) Matching Range One [Member] Defined Contribution Plan Range One [Member] Defined Contribution Plan Range One [Member] 401 (k) Matching Range Two [Member] Defined Contribution Plan Range Two [Member] Defined Contribution Plan Range Two [Member] Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] Legacy Cornerstone Bancshares, Inc. Long-Term Incentive Plan [Member] Legacy Cornerstone Bancshares, Inc. Long-Term Incentive Plan [Member] Legacy Cornerstone Bancshares, Inc. Long-Term Incentive Plan [Member] 2015 Stock Incentive Plan [Member] Stock Incentive Plan Two Thousand Fifteen [Member] Legacy Capstone Stock Option Plan [Member] Legacy Capstone Stock Option Plan [Member] Legacy Capstone Stock Option Plan [Member] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Nonstatutory Stock Option [Member] Nonstatutory Stock Option [Member] Nonstatutory Stock Option [Member] Stock Appreciation Rights (SARs) [Member] Stock Appreciation Rights (SARs) [Member] Stock Options [Member] Employee Stock Option [Member] Restricted Stock [Member] Restricted Stock [Member] Retirement Plan Name [Axis] Retirement Plan Name [Axis] Retirement Plan Name [Domain] Retirement Plan Name [Domain] Deferred Salary Reduction Plan [Member] Deferred Salary Reduction Plan [Member] Title of Individual [Axis] Title of Individual [Axis] Relationship to Entity [Domain] Relationship to Entity [Domain] Director [Member] Director [Member] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Request service period Defined Contribution Plan, Requisite Service Period Defined Contribution Plan, Requisite Service Period Employer matching contribution, percent of match Defined Contribution Plan, Employer Matching Contribution, Percent of Match Employer matching contribution, percent of employees gross pay Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay Deferred compensation arrangements, overall, description Deferred Compensation Arrangements, Overall, Description Defined contribution plan, cost recognized Defined Contribution Plan, Cost Number of stock option plans Share-Based Compensation Arrangement By Share-Based Payment Award, Number Of Stock Option Plans Share-Based Compensation Arrangement By Share-Based Payment Award, Number Of Stock Option Plans Number of inactive stock option plans with outstanding grants Share-Based Compensation Arrangement By Share-Based Payment Award, Number Of Inactive Stock Option Plans With Outstanding Grants Share-Based Compensation Arrangement By Share-Based Payment Award, Number Of Inactive Stock Option Plans With Outstanding Grants Exercise price, not less than (as a percent) Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent Number outstanding (in shares) Term of options, no more than Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Voting power held by participant (as a percent) Share-Based Compensation Arrangement, Ownership Percentage By Individual Share-based Compensation Arrangement, Ownership Percentage by Individual Term of option to participants with more than ten percent voting power Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Percentage of incentive stock options vesting on second anniversary Percentage Of Incentive Stock Options Vest On Second Anniversary Of Grant Date Percentage of incentive stock options vested on second anniversary of grant date. Percentage of incentive stock options vesting on third anniversary Percentage Of Incentive Stock Options Vest On Third Anniversary Of Grant Date Percentage of incentive of third anniversary of grant date. Percentage of incentive stock options vesting on fourth anniversary Percentage Of Incentive Stock Options Vest On Fourth Anniversary Of Grant Date Percentage of fourth anniversary of grant date. Percentage of nonqualified stock options vesting on first anniversary Percentage Of Nonqualified Stock Options Vest On First Anniversary Of Grant Date Percentage of non qualified stock options vested on first anniversary of grant date. Percentage of nonqualified stock options vesting on second anniversary Percentage Of Nonqualified Stock Options Vest On Second Anniversary Of Grant Date Percentage of non qualified stock options vested on second anniversaries of grant date. Share-based compensation expense Allocated Share-based Compensation Expense Direct stock grant expense Stock or Unit Option Plan Expense Options vested in period, fair value Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value Deferred tax expense from stock options exercised Deferred Tax Expense from Stock Options Exercised Options, exercises in period, intrinsic value Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Options, outstanding, intrinsic value Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Options, exercisable, intrinsic value Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Proceeds from stock options exercised Proceeds from Stock Options Exercised Unrecognized compensation costs Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options Unrecognized compensation costs, period for recognition Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Number of shares granted (in shares) Number of shares granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Grant date fair value (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Unrecognized compensation cost Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Fair Value, Assets and Liabilities Measured on Nonrecurring Basis Fair Value Measurements, Nonrecurring [Table Text Block] Fair Value, by Balance Sheet Grouping Fair Value, by Balance Sheet Grouping [Table Text Block] Loans Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Financial Assets Core deposit intangible Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill Deposits Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Financial Liabilities Payables and other liabilities Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Current Liabilities, Accounts Payable And Other Liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable and Other Liabilities Impaired loans, measurement input Impaired Loans, Measurement Input Impaired Loans, Measurement Input Foreclosed assets, measurement input Foreclosed Assets, Measurement Input Foreclosed Assets, Measurement Input Number of derivative instruments Derivative, Number of Instruments Held Notional amount Derivative, Notional Amount Summary of Premises and Equipment Schedule of Future Minimum Rental Payments for Operating Leases Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Financial Instrument Performance Status [Axis] Financial Instrument Performance Status [Axis] Financial Instrument Performance Status [Domain] Financial Instrument Performance Status [Domain] Performing [Member] Performing Financial Instruments [Member] Impaired Loans [Member] Nonperforming Financial Instruments [Member] Allowance for loan losses Aggregate amortization expense of core deposit premium intangible Operating Loss Carryforwards [Table] Operating Loss Carryforwards [Table] Adjustments for Error Corrections [Axis] Adjustments for Error Corrections [Axis] Adjustments for Error Correction [Domain] Adjustments for Error Correction [Domain] Income Taxes [Member] Exclusion Of A Tax Benefit From Non-Qualified Options Exercised [Member] Exclusion Of A Tax Benefit From Non-Qualified Options Exercised [Member] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] Domestic Tax Authority [Member] Domestic Tax Authority [Member] Operating Loss Carryforwards [Line Items] Operating Loss Carryforwards [Line Items] Decrease in tax provision Increase (Decrease) in Income Taxes Net operating loss carryforward Operating Loss Carryforwards Document And Entity Information [Abstract] Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Current Reporting Status Entity Current Reporting Status Entity Filer Category Entity Filer Category Entity Shell Company Entity Shell Company Entity Emerging Growth Company Entity Emerging Growth Company Entity Small Business Entity Small Business Entity Public Float Entity Public Float Trading Symbol Trading Symbol Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Shareholders' Equity Class [Axis] Shareholders' Equity Class [Axis] Fair Value by Shareholders' Equity Class [Domain] Fair Value by Shareholders' Equity Class [Domain] SBLF Program [Member] SBLF Program [Member] Class of Stock [Line Items] Class of Stock [Line Items] Share price (in dollars per share) Share Price Preferred stock, dividend rate (as a percent) Preferred Stock, Dividend Rate, Percentage Preferred stock dividends Issuance of common stock in public offering (in shares) Stock Issued During Period, Shares, New Issues Payments for redemption of preferred stock Payment of dividends on preferred stock Time Deposits Maturity [Table] Time Deposits Maturity [Table] Related Party [Axis] Related Party [Axis] Related Party [Domain] Related Party [Domain] Related Party [Member] Related Party [Member] Time Deposits Maturity [Line Items] Time Deposits Maturity [Line Items] Time deposits of 250,000 or more Time Deposits 250000 Or More The aggregate amount of domestic and foreign time deposit liabilities (including certificates of deposits, individual retirement accounts and open accounts) in denominations of $250,000 or more. Fair value adjustments to time deposits Fair Value Adjustments To Time Deposits On Business Combination Amount of fair value adjustments to time deposits as a result of the business combination. Deposit liabilities reclassified as loans receivable Deposit Liabilities Reclassified as Loans Receivable Related party deposit liabilities Related Party Deposit Liabilities Amortized intangible asset: Amortized Intangible Asset [Abstract] Gross Carrying Amount Finite-Lived Intangible Assets, Gross Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Regulatory Matters Regulatory Capital Requirements under Banking Regulations [Text Block] Loan Portfolio Secured by Real Estate [Member] Collateral Concentration Risk [Member] Collateral Concentration Risk [Member] Concentration risk (as a percent) Concentration Risk, Percentage Credit extending terms to borrowers Credit Extending Terms To Borrowers