Loans and Leases Receivable Disclosure [Abstract] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Internal Credit Assessment [Axis] Internal Credit Assessment [Axis] Financing Receivable, by Credit Quality Indicator [Domain] Internal Credit Assessment [Domain] Doubtful [Member] Doubtful [Member] Financing Receivable Portfolio Segment [Axis] Financing Receivable Portfolio Segment [Axis] Financing Receivable Portfolio Segment [Domain] Financing Receivable Portfolio Segment [Domain] PCI Loans [Member] Purchased Credit Impaired Loans [Member] Purchased Credit Impaired Loans [Member] Non-PCI Loans [Member] Non-Purchased Credit Impaired Loans [Member] Non-Purchased Credit Impaired Loans [Member] Loans Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Loans receivable, gross Loans and Leases Receivable, before Fees, Gross PCI Loans Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Outstanding Balance Outstanding discounts Loans and Leases Receivable, Deferred Income Serviced loans for others, aggregate amount Aggregate amount of loans serviced for others Aggregate amount of loans serviced by the Bank for others. Escrow balances on loans serviced for others escrow balances held on loans serviced for others Escrow balances held by the Bank on loans serviced for others. Loan-to-value ratio securing commercial real estate loans, maximum Loan To Value Ratio For Securing Commercial Real Estate Loans Maximum Loan To Value Ratio For Securing Commercial Real Estate Loans Maximum Debt service coverage ratio for commercial real estate loans, minimum Debt Service Coverage Ratio For Commercial Real Estate Loans Minimum For commercial real estate loans, the minimum acceptable debt service coverage ratio. Recorded investment of loans in process of foreclosure Mortgage Loans in Process of Foreclosure, Amount Carrying value of residential OREO Real Estate Acquired Through Foreclosure Loans receivable Loans and Leases Receivable, Net Amount ACL maintained for impaired loans Impaired Financing Receivable, Related Allowance ACL maintained for loans individually evaluated for impairment Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment Schedule of Financing Receivables Past Due [Table] Schedule of Financing Receivables Past Due [Table] One- to Four-Family Segment [Member] Residential Portfolio Segment [Member] Commercial Segment [Member] Commercial Portfolio Segment [Member] Consumer Segment [Member] Consumer Portfolio Segment [Member] Class of Financing Receivable [Axis] Class of Financing Receivable, Type [Axis] Financing Receivable, Recorded Investment, Class of Financing Receivable [Domain] Class of Financing Receivable, Type [Domain] Originated [Member] One To Four Family Loans Originated [Member] One To Four Family Loans Originated [Member] Correspondent Purchased [Member] One To Four Family Loans Correspondent Purchased [Member] Correspondent purchased loan secured by residential real estate as a single family home or a multi-unit dwelling of two to four units. Bulk Purchased [Member] One To Four Family Loans Bulk Purchased [Member] Bulk purchased loan secured by residential real estate as a single family home or a multi-unit dwelling of two to four units. Commercial Real Estate [Member] Commercial Real Estate Portfolio Segment [Member] Commercial and Industrial [Member] Commercial Loan [Member] Home Equity [Member] Home Equity Line of Credit [Member] Other [Member] Consumer Loan [Member] Financing Receivable, Recorded Investment, Past Due [Line Items] Financing Receivable, Recorded Investment, Past Due [Line Items] Financing receivable, nonaccrual loans Financing Receivable, Recorded Investment, Nonaccrual Status Schedule of Financing Receivable, Troubled Debt Restructurings [Table] Schedule of Financing Receivable, Troubled Debt Restructurings [Table] Financing Receivable, Modifications [Line Items] Financing Receivable, Modifications [Line Items] Number of Contracts Financing Receivable, Modifications, Number of Contracts Pre-Restructured Outstanding Financing Receivable, Modifications, Pre-Modification Recorded Investment Post-Restructured Outstanding Financing Receivable, Modifications, Post-Modification Recorded Investment Commitments and Contingencies Disclosure [Abstract] Unadvanced lines of credit Unadvanced Lines Of Credit Unadvanced Lines Of Credit Standby letters of credit outstanding Letters of Credit Outstanding, Amount Regulatory Capital Requirements [Abstract] Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table] Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table] Consolidated Entities [Axis] Consolidated Entities [Axis] Consolidated Entities [Domain] Consolidated Entities [Domain] Capitol Federal Financial Inc [Member] Parent Company [Member] Capitol Federal Savings Bank [Member] Subsidiaries [Member] Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] Tier 1 leverage, Actual Amount Tier One Leverage Capital Tier 1 leverage, Actual Ratio Tier One Leverage Capital to Average Assets Tier 1 leverage, For Capital Adequacy Purposes, Amount Tier One Leverage Capital Required for Capital Adequacy Tier 1 leverage, For Capital Adequacy Purposes, Ratio Tier One Leverage Capital Required for Capital Adequacy to Average Assets Tier 1 leverage, To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount Tier One Leverage Capital Required to be Well Capitalized Tier 1 leverage, To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio Tier One Leverage Capital Required to be Well Capitalized to Average Assets CET1 capital, Actual Amount Common Equity Tier One Capital CET1 capital, Actual Ratio Common Equity Tier One Capital Ratio CET1 capital, For Capital Adequacy Purposes, Amount Common Equity Tier One Capital Required for Capital Adequacy CET1 capital, For Capital Adequacy Purposes, Ratio Common Equity Tier 1 Capital, For Capital Adequacy Purposes, Ratio The minimum Common Equity Tier 1 Capital Ratio required for capital adequacy purposes as defined by the regulators. CET1 capital, To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount Common Equity Tier One Capital Required to be Well-Capitalized CET1 capital, To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio Common Equity Tier 1 Capital Ratio Required To Be Well Capitalized The Common Equity Tier 1 Capital Ratio required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action. Tier 1 capital, Actual Amount Tier One Risk Based Capital Tier 1 capital, Actual Ratio Tier One Risk Based Capital to Risk Weighted Assets Tier 1 capital, For Capital Adequacy Purposes, Amount Tier One Risk Based Capital Required for Capital Adequacy Tier 1 capital, For Capital Adequacy Purposes, Ratio Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets Tier 1 capital, To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount Tier One Risk Based Capital Required to be Well Capitalized Tier 1 capital, To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets Total capital, Actual Amount Capital Total capital, Actual Ratio Capital to Risk Weighted Assets Total capital, For Capital Adequacy Purposes, Amount Capital Required for Capital Adequacy Total capital, For Capital Adequacy Purposes, Ratio Capital Required for Capital Adequacy to Risk Weighted Assets Total capital, To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount Capital Required to be Well Capitalized Total capital, To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio Capital Required to be Well Capitalized to Risk Weighted Assets Marketable Securities [Abstract] Taxable Interest Income, Securities, Operating, Taxable Non-taxable Interest Income, Securities, Operating, Tax Exempt Interest income on investment securities Interest and Dividend Income, Securities, Operating Originate fixed-rate Loans and Leases Receivable, Commitments, Fixed Rates Originate adjustable-rate Loans and Leases Receivable, Commitments, Variable Rates Purchase/participate fixed-rate Commitments Outstanding To Purchase Fixed Rate Commitment to purchase/participate fixed-rate loans. Purchase/participate adjustable-rate Commitments Outstanding To Purchase Adjustable Rate Commitments to purchase/participate adjustable rate loans. Commitments outstanding to originate, purchase, or participate in loans Commitments Outstanding To Originate And Purchase Loans Commitments outstanding to originate and purchase loans. Schedule of Impaired Financing Receivable [Table] Schedule of Impaired Financing Receivable [Table] Financing Receivable, Impaired [Line Items] Financing Receivable, Impaired [Line Items] Recorded investment in loans collectively evaluated for impairment Financing Receivable, Collectively Evaluated for Impairment Recorded investment in loans individually evaluated for impairment Financing Receivable Individually Evaluated for Impairment, Recorded Investment The balance of financing receivables that were individually evaluated for impairment. Financing receivable, total recorded investment Loans and Leases Receivable, Net of Deferred Income ACL for loans collectively evaluated for impairment Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment Regulatory Capital Requirements Regulatory Capital Requirements under Banking Regulations [Text Block] Fair Value Disclosures [Abstract] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring [Member] Fair Value, Measurements, Recurring [Member] Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] GSE Debentures [Member] US Government-sponsored Enterprises Debt Securities [Member] MBS [Member] Residential Mortgage Backed Securities [Member] Municipal Bonds [Member] Municipal Bonds [Member] Trust Preferred Securities [Member] Trust Preferred Securities [Member] A collateralized debt obligation backed by a shared pool of trust preferred securities. Issuers include companies in highly regulated industries such as banks, insurance companies and regulated utilities as well as some general corporate issuers. Most are rated by one or more of the standard rating agencies. Fair Value, Hierarchy [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy and NAV [Domain] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] Fair Value, Inputs, Level 1 [Member] Significant Other Observable Inputs (Level 2) [Member] Fair Value, Inputs, Level 2 [Member] Significant Unobservable Inputs (Level 3) [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] AFS securities Available-for-sale Securities Interest rate swaps Derivative Asset Assets Assets, Fair Value Disclosure Interest rate swaps Derivative Liability Income Tax Disclosure [Abstract] Federal income tax expense computed at statutory Federal rate, Amount Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Federal income tax expense computed at statutory Federal rate, Percentage Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Increases (Decreases) In Taxes Resulting From: Increases (Decreases) In Taxes Abstract Increases (Decreases) in taxes resulting from: State taxes, net of Federal tax effect, Amount Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount State taxes, net of Federal tax effect, Percentage Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent Deferred tax liability remeasurement, net, Amount Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability Deferred tax liability remeasurement, net, Percentage Income Tax Expense (Benefit), Adjustment of Deferred Tax (Asset) Liability, Rate Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to adjustments of deferred tax assets and liabilities. Low income housing tax credits, presented net of proportional amortization in 2018 and 2017, Amount Effective Income Tax Rate Reconciliation, Tax Credit, Amount Low income housing tax credits, presented net of proportional amortization in 2018 and 2017, Percentage Effective Income Tax Rate Reconciliation, Tax Credit, Percent ESOP related expenses, net, Amount ESOP Related Expenses Net ESOP related expenses, net. ESOP related expenses, net, Percentage Effective Income Tax Rate ESOP Related Expenses Net Effective income tax rate ESOP related expenses, net. Other, Amount Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Other, Percentage Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Income tax expense Income Tax Expense (Benefit) Income tax expense, Percentage Effective Income Tax Rate Reconciliation, Percent Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Measurement Basis [Axis] Measurement Basis [Axis] Fair Value, Disclosure Item Amounts [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: Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract] Cash and cash equivalents Cash and Cash Equivalents, Fair Value Disclosure HTM securities Debt Securities, Held-to-maturity, Fair Value Loans receivable Loans Receivable, Fair Value Disclosure FHLB stock Investment in Federal Home Loan Bank Stock, Fair Value Disclosure Liabilities: Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract] Deposits Deposits, Fair Value Disclosure FHLB borrowings Federal Home Loan Bank Borrowings, Fair Value Disclosure Other borrowings Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure Employee Stock Ownership Plan (ESOP), Shares in ESOP [Abstract] Employee Benefit Plans Compensation and Employee Benefit Plans [Text Block] Goodwill and Intangible Assets Disclosure [Abstract] Schedule of Goodwill and Intangible Assets [Table] Schedule of Goodwill and Intangible Assets [Table] Schedule of Goodwill and Intangible Assets [Table] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Capital City Bancshares, Inc. [Member] Capital City Bancshares [Member] Capital City Bancshares [Member] Schedule of Goodwill and Intangible Assets [Line Items] Schedule of Goodwill and Intangible Assets [Line Items] [Line Items] for Schedule of Goodwill and Intangible Assets [Table] Goodwill, Beginning Balance Goodwill Goodwill, Acquired During Period Goodwill, Acquired During Period Goodwill, Amortization Amortization Of Goodwill The aggregate expense charged against earnings to amortize goodwill Goodwill, Ending Balance Core Deposit and Other Intangibles, Beginning Balance Finite-Lived Intangible Assets, Net Core Deposit and Other Intangibles, Acquired During Period Finite-lived Intangible Assets Acquired Core Deposit and Other Intangibles, Amortization Amortization of Intangible Assets Core Deposit and Other Intangibles, Ending Balance Selected Quarterly Financial Information [Abstract] Summary Of Quarterly Data Quarterly Financial Information [Table Text Block] 2019 Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months 2020 Finite-Lived Intangible Assets, Amortization Expense, Year Two 2021 Finite-Lived Intangible Assets, Amortization Expense, Year Three 2022 Finite-Lived Intangible Assets, Amortization Expense, Year Four 2023 Finite-Lived Intangible Assets, Amortization Expense, Year Five Accounting Policies [Abstract] Summary Of Significant Accounting Policies [Table] Summary Of Significant Accounting Policies [Table] Summary Of Significant Accounting Policies [Table] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Traditional Banking Offices [Member] Traditional Banking Offices [Member] Traditional Banking Offices [Member] In-Store Banking Offices [Member] In Store Banking Offices [Member] In-Store Banking Offices [Member] Summary Of Significant Accounting Policies [Line Items] Summary Of Significant Accounting Policies [Line Items] Summary Of Significant Accounting Policies [Line Items] Number of Stores Number of Stores Interest-bearing deposits held at the Federal Reserve Bank Interest Bearing Deposits Held At Federal Reserve Bank Interest Bearing Deposits Held At Federal Reserve Bank Average daily balance of required reserves at the Federal Reserve Bank Average Daily Required Reserve Balance At Federal Reserve Bank Average Daily Required Reserve Balance At Federal Reserve Bank Other intangible assets, estimated life Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Equity [Abstract] Other Comprehensive Income Comprehensive Income (Loss) Note [Text Block] Commitments Outstanding To Originate, Purchase, Or Participate In Loans Commitments Outstanding To Originate And Purchase Loans [Table Text Block] Commitments Outstanding To Originate And Purchase Loans [Table Text Block] Statement of Comprehensive Income [Abstract] Net income Net Income (Loss) Attributable to Parent Other comprehensive income (loss), net of tax: Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Changes in unrealized gains (losses) on AFS securities, net of taxes of $2,499, $1,595, and $1,494 Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, after Tax Changes in unrealized gains (losses) on cash flow hedges, net of taxes of $(2,785), $226, and $0 Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax, Portion Attributable to Parent Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Selected Quarterly Financial Data (Unaudited) Quarterly Financial Information [Text Block] Changes in unrealized gains (losses) on AFS securities, deferred income taxes Other Comprehensive Income (Loss), Securities, Available-for-sale, Tax Changes in unrealized gains (losses) on cash flow hedges, deferred income taxes Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax, Portion Attributable to Parent Property, Plant and Equipment, Net [Abstract] 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 Future minimum rental commitments, total Operating Leases, Future Minimum Payments Due Investment Holdings [Table] Investment Holdings [Table] Schedule of Investments [Line Items] Schedule of Investments [Line Items] Available-for-sale Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Estimated Fair Value Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value Available-for-sale Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Unrealized Losses Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Available-for-sale Securities, Continuous Unrealized Loss Position, Equal to or Greater Than 12 Months, Estimated Fair Value Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value Available-for-sale Securities, Continuous Unrealized Loss Position, Equal to or Greater Than 12 Months, Unrealized Losses Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Held-to-maturity Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Estimated Fair Value Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value Held-to-maturity Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Unrealized Losses Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Held-to-maturity Securities, Continuous Unrealized Loss Position, Equal to or Greater Than 12 Months, Estimated Fair Value Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value Held-to-maturity Securities, Continuous Unrealized Loss Position, Equal to or Greater Than 12 Months, Unrealized Losses Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Share-based Compensation [Abstract] Stock-Based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Earnings Per Share [Abstract] Earnings Per Share Earnings Per Share [Text Block] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Earnings Per Share Reconciliation Effect On Basic Earnings Per Share [Axis] Earnings Per Share Reconciliation Effect On Basic Earnings Per Share [Axis] Earnings Per Share Reconciliation, Effect On Basic Earnings Per Share [Axis] Earnings Per Share Reconciliation Effect On Basic Earnings Per Share [Domain] Earnings Per Share Reconciliation Effect On Basic Earnings Per Share [Domain] Earnings Per Share Reconciliation Effect On Basic Earnings Per Share [Domain] Average Common Shares Outstanding [Member] Average Common Shares Outstanding [Member] Average common shares outstanding Average Committed ESOP Shares Outstanding [Member] Average Committed Employee Stock Ownership Plan Shares Outstanding [Member] Average committed employee stock ownership plan shares outstanding Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Earnings Per Share Earnings Per Share Reconciliation [Abstract] Income allocated to participating securities Undistributed Earnings (Loss) Allocated to Participating Securities, Basic Net income available to common stockholders Net Income (Loss) Available to Common Stockholders, Basic Total basic average common shares outstanding Weighted Average Number of Shares Outstanding, Basic Effect of dilutive stock options Weighted Average Number Diluted Shares Outstanding Adjustment Total diluted average common shares outstanding Weighted Average Number of Shares Outstanding, Diluted Net EPS: Earnings Per Share, Basic and Diluted [Abstract] Basic Earnings Per Share, Basic Diluted Earnings Per Share, Diluted Antidilutive stock options, excluded from the diluted average common shares outstanding calculation Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Share-based Arrangements with Employees and Nonemployees [Abstract] Schedule of Employee Stock Ownership Plan (ESOP) Disclosures [Table] Schedule of Employee Stock Ownership Plan (ESOP) Disclosures [Table] Subsidiary, Sale of Stock [Axis] Sale of Stock [Axis] Sale of Stock, Name of Transaction [Domain] Sale of Stock [Domain] IPO [Member] IPO [Member] Corporate Reorganization [Member] Corporate Reorganization [Member] Corporate Reorganization [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum [Member] Minimum [Member] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Forecast [Member] Scenario, Forecast [Member] Employee Stock Ownership Plan (ESOP) Disclosures [Line Items] Employee Stock Ownership Plan (ESOP) Disclosures [Line Items] Number of shares acquired by ESOP trust Number Shares Acquired By Employee Stock Ownership Plan Number of shares acquired by employee stock ownership plan. Number of shares acquired by ESOP post corporate reorganization Number Of Shares Acquired By Employee Stock Ownership Plan Post Corporate Reorganization Number Of Shares Acquired By Employee Stock Ownership Plan Post Corporate Reorganization ESOP loan maturity date Debt Instrument, Maturity Date Shares Held In Employee Stock Ownership Plan, Allocated Shares Held In Employee Stock Ownership Plan Allocated Number of allocated shares held by the Employee Stock Ownership Plan at balance sheet date. Allocated shares are shares that have been assigned to individual participant accounts based on a known formula. Shares Held In Employee Stock Ownership Plan, Committed-to-be-Released Employee Stock Ownership Plan (ESOP), Number of Committed-to-be-Released Shares Compensation expense related to the ESOP including dividends Employee Stock Ownership Plan ESOP Compensation Expense Including Dividends On Unallocated Shares In Excess Of Debt Service Payments Employee Stock Ownership Plan ESOP Compensation Expense Including Dividends On Unallocated Shares In Excess Of Debt Service Payments Portion of compensation expense related to the ESOP attributable to changes in Company stock price Portion Of Compensation Expense Related To ESOP Attributable To Changes In Company Stock Price Portion Of Compensation Expense Related To ESOP Attributable To Changes In Company Stock Price Dividends on unallocated ESOP shares in excess of debt service payments Employee Stock Ownership Plan (ESOP), Dividends Paid to ESOP Percentage of ESOP shares participant may diversify once age requirement is met Percentage Of Employee Stock Ownership Plan Shares Diversified Percentage of Employee Stock Ownership Plan shares diversified Required age of participant in order to diversify ESOP shares, years Age Period Of Diversified Employee Stock Ownership Plan Shares Age at which employee ESOP participants may begin to diversify their ESOP shares into other investments. Federal corporate income tax rate Revaluation of net deferred tax liability Impairment of low income housing partnership investments Affordable Housing Project Investment, Write-down, Amount Effective income tax rate Valuation allowance Deferred Tax Assets, Valuation Allowance Unrecognized tax benefits Unrecognized Tax Benefits Open tax year Open Tax Year Schedule of Accumulated Other Comprehensive Income (Loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Class of Financing Receivable [Domain] Construction [Member] Construction Loans [Member] ACL Loans and Leases Receivable, Allowance Discounts/unearned loan fees Premiums/deferred costs Loans And Leases Receivable Premiums Deferred Costs Loans And Leases Receivable Premiums Deferred Costs Loans receivable, net Statement of Financial Position [Abstract] ASSETS: Assets [Abstract] Cash and cash equivalents (includes interest-earning deposits of $122,733 and $340,748) Cash and Cash Equivalents, at Carrying Value Securities: Available-for-sale (AFS), at estimated fair value (amortized cost of $718,564 and $410,541) Held-to-maturity (HTM), at amortized cost (estimated fair value of $601,071 and $833,009) Debt Securities, Held-to-maturity Loans receivable, net (allowance for credit losses (ACL) of $8,463 and $8,398) Federal Home Loan Bank Topeka (FHLB) stock, at cost Federal Home Loan Bank Stock Premises and equipment, net Property, Plant and Equipment, Net Income taxes receivable, net Income Taxes Receivable Other assets Other Assets TOTAL ASSETS Assets LIABILITIES: Liabilities [Abstract] Deposits Deposits, Domestic FHLB borrowings Long-term Federal Home Loan Bank Advances Other borrowings Securities Sold under Agreements to Repurchase Advance payments by borrowers for taxes and insurance Advance Payments by Borrowers for Taxes and Insurance Income taxes payable, net Accrued Income Taxes, Current Deferred income tax liabilities, net Deferred Tax Liabilities, Net Accounts payable and accrued expenses Accounts Payable and Other Accrued Liabilities Total liabilities Liabilities STOCKHOLDERS' EQUITY: Stockholders' Equity Attributable to Parent [Abstract] Preferred stock, $.01 par value; 100,000,000 shares authorized, no shares issued or outstanding Preferred Stock, Value, Issued Common stock, $.01 par value; 1,400,000,000 shares authorized; 141,225,516 and 138,223,835 shares issued and outstanding as of September 30, 2018 and 2017, respectively Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital, Common Stock Unearned compensation, Employee Stock Ownership Plan (ESOP) Unearned ESOP Shares Retained earnings Retained Earnings (Accumulated Deficit) Accumulated other comprehensive income (AOCI), net of tax Accumulated Other Comprehensive Income (Loss), Net of Tax Total stockholders' equity Stockholders' Equity Attributable to Parent TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY Liabilities and Equity Property, Plant and Equipment [Table] Land [Member] Land [Member] Building and Improvements [Member] Building and Building Improvements [Member] Furniture, Fixtures and Equipment [Member] Furniture and Fixtures [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Property, plant and equipment, gross Property, Plant and Equipment, Gross Accumulated depreciation, property, plant and equipment Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Property, plant and equipment, net Fair Value, Measurements, Nonrecurring [Member] Fair Value, Measurements, Nonrecurring [Member] Measurement Input Type [Axis] Measurement Input Type [Axis] Measurement Input Type [Domain] Measurement Input Type [Domain] Estimated Selling Costs [Member] Measurement Input, Cost to Sell [Member] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Other Income [Member] Other Income [Member] Proceeds received from sale of AFS securities Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales Gain on sale of AFS securities Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings Proceeds from principal repayments Proceeds from Maturities, Prepayments and Calls of Debt Securities, Available-for-sale (Decreases) increases in net unrealized losses included in OCI Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) Loans individually evaluated for impairment Loans receivable, measurement input Loans Receivable, Measurement Input Value of input used by financial institution to measure loans receivable at fair value OREO Other Real Estate OREO, measurement input Other Real Estate Owned, Measurement Input Estimated fair value of deposits Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Award Type [Axis] Award Type [Axis] Share-based Compensation Arrangements by Share-based Payment Award, Award Type and Plan Name [Domain] Equity Award [Domain] Stock Option Plans [Member] Stock Compensation Plan [Member] Restricted Stock Plans [Member] Restricted Stock [Member] Incentive Stock Options [Member] Incentive Stock Options [Member] Incentive Stock Options [Member] Nonqualified Stock Options [Member] Nonqualified Stock Options [Member] Nonqualified Stock Options [Member] Maximum [Member] Maximum [Member] Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] 2000 Stock Option Plan [Member] Two Thousand Stock Option Plan [Member] Two Thousand Stock Option Plan [Member] 2012 Equity Incentive Plan [Member] Two Thousand Twelve Equity Incentive Plan [Member] Two Thousand Twelve Equity Incentive Plan [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Shares of common stock reserved for future issuance Common Stock, Capital Shares Reserved for Future Issuance Contractual term of stock options Share-based Compensation Arrangement By Share-based Payment Award, Options Outstanding Contractual Term Contractual term of stock options. Plan expiration date Share-based Compensation Arrangement by Share-based Payment Award, Expiration Date Vesting period of options Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Options outstanding at end of year, number of options Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Options outstanding at end of year, weighted average exercise price Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Options outstanding at end of year, weighted average remaining contractual life (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Options exercisable at end of year, number of options Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Options exercisable at end of year, weighted average exercise price Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Options exercisable at end of year, weighted average remaining contractual life (in years) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Number of shares available for future grants Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Vesting period of restricted stock Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period Compensation expense Allocated Share-based Compensation Expense Fair value of stock options vested during the period Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, In Period, Fair Value Fair value of stock options vested during the period. Unrecognized total future compensation cost Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Unvested restricted stock at end of year, number of shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Unvested restricted stock at end of year, weighted average grant date fair value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Unrecognized total future compensation cost, net of forfeitures Employee service share based compensation nonvested awards total compensation cost not yet recognized net of forfeitures Unrecognized cost of unvested share-based compensation awards, net of forfeitures. Fair value of restricted stock vested during the period Share based compensation arrangement by share based payment award restricted stock vested in period fair value Fair value of restricted stock that vested during the period. Unrecognized total future compensation cost weighted average recognition period Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Summary Of The Carrying Value Of Banking Premises And Equipment Property, Plant and Equipment [Table Text Block] Schedule Of Future Minimum Rental Commitments Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Amortized Cost, Estimated Fair Value, and Gross Unrealized Gains and Losses Of AFS Securities Available-for-sale Securities [Table Text Block] Amortized Cost, Estimated Fair Value, and Gross Unrealized Gains and Losses Of HTM Securities Debt Securities, Held-to-maturity [Table Text Block] Schedule Of Estimated Fair Value And Gross Unrealized Losses Of Securities In Continuous Unrealized Loss Position Unrealized Gain (Loss) on Investments [Table Text Block] Schedule Of Contractual Maturities Investments Classified by Contractual Maturity Date [Table Text Block] Schedule Of Taxable And Non-taxable Components Of Interest Income Interest Income and Interest Expense Disclosure [Table Text Block] Schedule Of Carrying Value Of Securities Pledged As Collateral Schedule Of Carrying Value Of Securities Pledged As Collateral Table Text Block Schedule Of Carrying Value Of Securities Pledged As Collateral. Schedule of Financing Receivable, Recorded Investment, Credit Quality Indicator [Table] Schedule of Financing Receivable, Recorded Investment, Credit Quality Indicator [Table] Financing Receivable, Recorded Investment [Line Items] Financing Receivable, Recorded Investment [Line Items] Weighted average credit score Weighted Average Credit Score Weighted Average Credit Score Weighted average LTV Weighted Average Loan To Value Ratio Weighted Average Loan To Value Ratio. Total interest and dividend income Interest and Dividend Income, Operating Net interest and dividend income Interest Income (Expense), Net Provision for credit losses Provision for Loan and Lease Losses Net income Basic EPS Diluted EPS Dividends declared per share Common Stock, Dividends, Per Share, Declared Average number of basic shares outstanding Average number of diluted shares outstanding Debt Disclosure [Abstract] Schedule of Short-term Debt [Table] Schedule of Short-term Debt [Table] Debt, Type [Axis] Short-term Debt, Type [Axis] Debt, Type [Domain] Short-term Debt, Type [Domain] FHLB Advances [Member] Federal Home Loan Bank Advances [Member] Weighted Average [Member] Weighted Average [Member] Debt [Line Items] Short-term Debt [Line Items] FHLB advances Advances from Federal Home Loan Banks Deferred prepayment penalty Prepayment Penalty On FHLB Advances Penalty paid as a result of prepaying FHLB advances. Deferred penalty is recognized in interest expense over the life of the new advances. FHLB advances, outstanding balance Weighted average contractual interest rate on FHLB advances Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Interest Rate at Period End Weighted average effective interest rate on FHLB advances Effective Rate FHLB Advances States the interest rate applicable to Federal Home Loan Bank advances outstanding as of the Balance Sheet date, including the net impact of interest rate swaps and the amortization of deferred prepayment penalties ACL Deferred Income Tax Expense Benefit Allowance For Credit Losses The change during the period in the entity's deferred tax assets and liabilities attributable to the allowance for credit losses. Salaries, deferred compensation and employee benefits Deferred Income Tax Expense Benefit Salaries Deferred Compensation and Employee Benefits The change during the period in the entity's deferred tax assets and liabilities attributable to salaries, deferred compensation, and employee benefits. Low income housing partnerships Deferred Income Tax Expense Benefit Low Income Housing Partnerships The change during the period in the entity's deferred tax assets and liabilities attributable to low income housing partnerships. FHLB stock dividends Deferred Income Tax Expense Benefit FHLB Stock Dividends The change during the period in the entity's deferred tax assets and liabilities attributable to FHLB stock dividends. Premises and equipment Deferred Income Tax Expense Benefit Fixed Assets The change during the period in the entity's deferred tax assets and liabilities attributable to fixed assets. Other, net Deferred Other Tax Expense (Benefit) Deferred income tax expense Deferred Income Tax Expense (Benefit) Schedule of Financing Receivable, Allowance for Credit Losses [Table] Schedule of Financing Receivable, Allowance for Credit Losses [Table] Financing Receivable, Allowance for Credit Losses [Line Items] Financing Receivable, Allowance for Credit Losses [Line Items] Beginning Balance Financing Receivable, Allowance for Credit Losses Charge-offs Financing Receivable, Allowance for Credit Losses, Write-downs Recoveries Financing Receivable, Allowance for Credit Losses, Recovery Provision for credit losses Provision for Loan, Lease, and Other Losses Ending Balance Schedule of Goodwill and Intangible Assets Schedule of Intangible Assets and Goodwill [Table Text Block] Schedule of Core Deposit and Other Intangible Assets, Future Amortization Expense Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Rental expense Operating Leases, Rent Expense, Net Deposits and Borrowed Funds [Abstract] Deposits and Borrowed Funds [Abstract] Schedule Of Borrowed Funds [Table] Schedule Of Borrowed Funds [Table] Schedule Of Borrowed Funds [Table] Leverage Strategy [Member] Leverage Strategy [Member] Leverage Strategy [Member] Subordinated Debentures Subject to Mandatory Redemption [Member] Subordinated Debentures Subject to Mandatory Redemption [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Capital City Statutory Trust I [Member] Capital City Statutory Trust I [Member] Represents a business trust that was formed for the purpose of issuing mandatorily redeemable trust-preferred securities to third-party investors and investing the proceeds from the sale of such securities solely in junior subordinated debentures of the Company. Capital City Statutory Trust II [Member] Capital City Statutory Trust II [Member] Represents a business trust that was formed for the purpose of issuing mandatorily redeemable trust-preferred securities to third-party investors and investing the proceeds from the sale of such securities solely in junior subordinated debentures of the Company. Statement [Line Items] Statement [Line Items] Noninterest-bearing deposits Noninterest-bearing Deposit Liabilities, Domestic Time Deposits, $250,000 or more Time Deposits, at or Above FDIC Insurance Limit FHLB borrowings, outstanding balance FHLB Advances, Fixed Rate Federal Home Loan Bank, Advances, Maturities Summary, Fixed Rate FHLB Advances, Variable Rate Federal Home Loan Bank, Advances, Maturities Summary, Floating Rate FHLB line of credit, outstanding balance Long-term Line of Credit FHLB line of credit available for leverage strategy, maximum Federal Home Loan Bank, Advances, General Debt Obligations, Maximum Amount Available Expiration date for FHLB line of credit Line of Credit Facility, Expiration Date Interest rate swaps, notional amount Derivative Asset, Notional Amount Interest rate swaps, notional amount Derivative Liability, Notional Amount Interest rate swaps, remaining term to maturity Derivative, Average Remaining Maturity Interest rate swaps, fair value Derivative, Fair Value, Net Interest rate swaps, amount reclassified from AOCI Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net Interest rate swaps, future amount to be reclassified from AOCI Derivative Instruments, Gain (Loss) Reclassification from Accumulated OCI to Income, Estimated Net Amount to be Transferred Interest rate swaps, amount of hedge ineffectiveness recognized Loss on Cash Flow Hedge Ineffectiveness Interest rate swaps, collateral held Derivative Asset, Fair Value of Collateral Interest rate swaps, collateral posted Collateral Already Posted, Aggregate Fair Value FHLB borrowings threshold percentage of regulatory assets F H L B Borrowings Threshold Percentage Of Regulatory Assets FHLB Borrowings Threshold Percentage Of Regulatory Assets FHLB borrowings threshold percentage of regulatory assets, temporary increase FHLB borrowings threshold percentage of regulatory assets, temporary increase Increased FHLB borrowing limit (as a percentage of regulatory assets) as approved by the FHLB president for one year. FHLB percentage of regulatory assets Fhlb Percentage Of Regulatory Assets FHLB advances as a percentage of total assets reported to regulator. Repurchase agreements Long-term Debt, Maturities, Repayments of Principal in Year Two Weighted average rate of repurchase agreements Assets Sold under Agreements to Repurchase, Interest Rate Repurchase Agreements, Description of Potential Risks Repurchase Agreements, Securities Lending Transactions, and Repurchase-to-Maturity Transactions Accounted for as Secured Borrowings, Description of Potential Risks Junior subordinated debentures Debt Instrument, Face Amount Common equity securities issued by the Trusts Common Stock Held in Trust Effective interest rate Debt Instrument, Interest Rate, Effective Percentage Maturity date Variable rate basis Debt Instrument, Description of Variable Rate Basis Interest rate spread over variable rate basis Debt Instrument, Basis Spread on Variable Rate Commitments And Contingencies Commitments and Contingencies Disclosure [Text Block] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Business Acquisition [Line Items] Business Acquisition [Line Items] Goodwill recognized upon acquisition of CCB Other intangible assets recognized upon acquisition of CCB Goodwill, impairment recorded Goodwill, Impaired, Accumulated Impairment Loss Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Condensed Financial Information Disclosure [Abstract] Statement [Table] Statement [Table] CASH FLOWS FROM OPERATING ACTIVITIES: Net Cash Provided by (Used in) Operating Activities [Abstract] 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] Equity in excess of distribution over earnings of subsidiary Equity In Excess Of Distribution Over Undistributed Earnings Of Subsidiary Equity in excess of distribution over/(undistributed) earnings of subsidiary Depreciation of equipment Depreciation, Nonproduction Provision for deferred income taxes Changes in: Increase (Decrease) in Operating Capital [Abstract] Other assets Increase (Decrease) in Other Operating Assets Income taxes receivable/payable Increase Decrease Income Taxes The net change during a reporting period of income taxes payable/receivable and deferred income tax assets/liabilities. Accounts payable and accrued expenses Increase (Decrease) in Accounts Payable and Accrued Liabilities 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 [Abstract] Principal collected on notes receivable from ESOP Proceeds from Collection of Notes Receivable Cash acquired from acquisition Cash Acquired from Acquisition Net cash (used in) provided by investing activities Net Cash Provided by (Used in) Investing Activities CASH FLOWS FROM FINANCING ACTIVITIES: Net Cash Provided by (Used in) Financing Activities [Abstract] Net payment from subsidiary related to restricted stock awards Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Excluding Stock Options Cash dividends paid Payments of Dividends Stock options exercised Proceeds from Stock Options Exercised Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS Cash and Cash Equivalents, Period Increase (Decrease) CASH AND CASH EQUIVALENTS: Cash and Cash Equivalents, at Carrying Value [Abstract] Beginning of year End of year SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING AND FINANCING ACTIVITIES: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Common stock issued for acquisition Stock Issued Capital contribution to subsidiary in conjunction with acquisition of CCB Capital Contributions To Subsidiaries The fair value of capital contributions to subsidiaries during the period in noncash transactions Current, Federal Current Federal Tax Expense (Benefit) Current, State Current State and Local Tax Expense (Benefit) Current income tax expense Current Federal, State and Local, Tax Expense (Benefit) Deferred, Federal Deferred Federal Income Tax Expense (Benefit) Deferred, State Deferred State and Local Income Tax Expense (Benefit) Deferred income tax expense Deferred Federal, State and Local, Tax Expense (Benefit) Schedule of Held-to-maturity Securities [Table] Debt Securities, Held-to-maturity [Table] Schedule of Held-to-maturity Securities [Line Items] Schedule of Held-to-maturity Securities [Line Items] Held-to-maturity Securities, Amortized Cost Held-to-maturity Securities, Gross Unrealized Gains Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain Held-to-maturity Securities, Gross Unrealized Losses Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss Held-to-maturity securities, Estimated Fair Value Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Line Items] Debt Securities, Available-for-sale [Line Items] Available-for-sale Securities, Amortized Cost Available-for-sale Securities, Amortized Cost Basis Available-for-sale Securities, Gross Unrealized Gains Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax Available-for-sale Securities, Gross Unrealized Losses Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax Available-for-sale Securities, Estimated Fair Value Statement of Cash Flows [Abstract] Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest FHLB stock dividends Dividend Income, Operating Originations of loans receivable held-for-sale (LHFS) Payments for Origination of Mortgage Loans Held-for-sale Proceeds from sales of LHFS Proceeds from Sale of Mortgage Loans Held-for-sale Amortization and accretion of premiums and discounts on securities Accretion (Amortization) of Discounts and Premiums, Investments Depreciation and amortization of premises and equipment Amortization of intangible assets Amortization of deferred amounts related to FHLB advances, net Amortization of Deferred Amounts Related to fhlb Advances, Net Includes amortization of deferred gains and prepayment penalties related to FHLB advances or derivatives related to FHLB advances. Common stock committed to be released for allocation - ESOP Employee Stock Ownership Plan (ESOP), Compensation Expense Stock-based compensation Share-based Compensation Changes in cash collateral received from derivative counterparty, net Increase (Decrease) Cash Collateral from Counterparties Other assets, net Income taxes payable, net Increase (Decrease) in Income Taxes Payable Purchase of AFS securities Payments to Acquire Available-for-sale Securities Purchase of HTM securities Payments to Acquire Held-to-maturity Securities Proceeds from calls, maturities and principal reductions of AFS securities Proceeds from calls, maturities and principal reductions of HTM securities Proceeds from Maturities, Prepayments and Calls of Held-to-maturity Securities Proceeds from sale of AFS securities Proceeds from Sale of Available-for-sale Securities Proceeds from the redemption of FHLB stock Proceeds from Sale of Federal Home Loan Bank Stock Purchase of FHLB stock Payments to Acquire Federal Home Loan Bank Stock Net increase in loans receivable Payments for (Proceeds from) Loans and Leases Purchase of premises and equipment Payments to Acquire Property, Plant, and Equipment Proceeds from sale of other real estate owned (OREO) Proceeds from Sale of Foreclosed Assets Proceeds from BOLI death benefit Proceeds from Life Insurance Policy Net change in deposits Increase (Decrease) in Deposits Proceeds from borrowings Proceeds from FHLBank Borrowings, Financing Activities Repayments on borrowings Payments of FHLBank Borrowings, Financing Activities Change in advance payments by borrowers for taxes and insurance Increase (Decrease) in Advance Payments by Borrowers for Taxes and Insurance Excess tax benefits from stock options Excess Tax Benefit from Share-based Compensation, Financing Activities SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION: Supplemental Cash Flow Information [Abstract] Income tax payments Income Taxes Paid Interest payments Interest Paid, Excluding Capitalized Interest, Operating Activities Loans transferred to LHFS Transfer of Portfolio Loans and Leases to Held-for-sale Common stock issued Fair value of assets acquired, excluding acquired cash and intangibles Fair Value of Assets Acquired Fair value of liabilities assumed Liabilities Assumed Deferred income tax assets: Components of Deferred Tax Assets [Abstract] Salaries, deferred compensation and employee benefits Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Employee Benefits Net purchase discounts related to acquired loans Deferred Tax Assets, Deferred Income ESOP compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Postretirement Benefits Unrealized loss on AFS securities Deferred Tax Assets, Unrealized Losses on Available-for-Sale Securities, Gross Low income housing partnerships Deferred Tax Assets, Investments ACL Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Provision for Loan Losses Other Deferred Tax Assets, Other Gross deferred income tax assets Deferred Tax Assets, Gross Valuation allowance Gross deferred income tax asset, net of valuation allowance Deferred Tax Assets, Net of Valuation Allowance Deferred income tax liabilities: Components of Deferred Tax Liabilities [Abstract] FHLB stock dividends Deferred Tax Liabilities Federal Home Loan Bank Stock Dividends Deferred income tax liabilities relating to FHLB stock dividends. Premises and equipment Deferred Tax Liabilities, Property, Plant and Equipment Deposit intangible Deferred Tax Liabilities, Intangible Assets Unrealized gain on interest rate swap Deferred Tax Liabilities, Derivatives ACL Deferred Tax Liabilities, Allowance For Credit Losses Amount of deferred tax liability attributable to allowance for credit losses Unrealized gain on AFS securities Deferred Tax Liabilities, Unrealized Gains On Available-for-Sale Securities Amount of deferred tax liability attributable to taxable temporary differences from unrealized gains on available-for-sale securities. Other Deferred Tax Liabilities, Other Gross deferred income tax liabilities Deferred Tax Liabilities, Gross Net deferred tax liabilities Liquidation account balance Liquidation Account The amount equal to the former mutual holding company's ownership interest in the retained earnings of the former company, as determined as of a specific date, for the benefit of certain depositors of the Bank. Capital Conservation Buffer, Annual Increase Capital Conservation Buffer, Annual Increase Amount of annual percentage increase in required capital conservation buffer above minimum risk-based capital ratios Required Capital Conservation Buffer Required Capital Conservation Buffer Amount of required capital conservation buffer above minimum risk-based capital ratios Capital Conservation Buffer, Fully Phased-In Percentage Capital Conservation Buffer, Fully Phased-In Percentage Percent above minimum risk-based capital ratios of capital conservation buffer once fully phased-in Income Statement [Abstract] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Deposit Account [Member] Deposit Account [Member] INTEREST AND DIVIDEND INCOME: Interest and Dividend Income, Operating [Abstract] Loans receivable Interest and Fee Income, Loans and Leases Cash and cash equivalents Interest Income, Deposits with Financial Institutions Mortgage-backed securities (MBS) Interest Income, Securities, Mortgage Backed FHLB stock Investment securities Total interest and dividend income INTEREST EXPENSE: Interest Expense [Abstract] FHLB borrowings Interest Expense, Federal Home Loan Bank and Federal Reserve Bank Advances, Long-term Deposits Interest Expense, Deposits Other borrowings Interest Expense, Securities Sold under Agreements to Repurchase Total interest expense Interest Expense NET INTEREST INCOME PROVISION FOR CREDIT LOSSES NET INTEREST INCOME AFTER PROVISION FOR CREDIT LOSSES Interest Income (Expense), after Provision for Loan Loss NON-INTEREST INCOME: Noninterest Income [Abstract] Deposit service fees Revenue from Contract with Customer, Excluding Assessed Tax Income from bank-owned life insurance (BOLI) Bank Owned Life Insurance Income Other non-interest income Noninterest Income, Other Total non-interest income Noninterest Income NON-INTEREST EXPENSE: Noninterest Expense [Abstract] Salaries and employee benefits Labor and Related Expense Information technology and related expense Communications and Information Technology Occupancy, net Occupancy, Net Regulatory and outside services Regulatory And Professional Fees Fees charged for services from professionals such as lawyers and accountants, and fees paid to regulators for conducting regulatory examinations. Deposit and loan transaction costs Deposit And Loan Transaction Costs Expense paid for miscellaneous loan fees that are not deferred, and fees related to deposit transactions, such as debit card processing, electronic banking, and ATM networks. Advertising and promotional Advertising Expense Federal insurance premium Federal Deposit Insurance Corporation Premium Expense Office supplies and related expense Supplies and Postage Expense Low income housing partnerships Low Income Housing Partnerships Non-interest expense related to low income housing partnership investments. Other non-interest expense Other Noninterest Expense Total non-interest expense Noninterest Expense INCOME BEFORE INCOME TAX EXPENSE Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest INCOME TAX EXPENSE NET INCOME Basic earnings per share (EPS) Diluted EPS Cash and cash equivalents Investment in the Bank Investment In Bank And Parent Company Parent company investment in bank subsidiary. Note receivable - ESOP E S O P Note Receivable ESOP note receivable. LIABILITIES AND STOCKHOLDERS' EQUITY Liabilities and Equity [Abstract] Unearned compensation - ESOP AOCI, net of tax Accumulated Other Comprehensive Income (Loss), Debt Securities, Available-for-sale, Adjustment, after Tax Preferred stock, par value Preferred Stock, Par or Stated Value Per Share Preferred stock, shares authorized Preferred Stock, Shares Authorized Preferred stock, shares issued Preferred Stock, Shares Issued Preferred stock, shares outstanding Preferred Stock, Shares Outstanding Common stock, par value Common Stock, Par or Stated Value Per Share Common stock, shares authorized Common Stock, Shares Authorized Common stock, shares issued Common Stock, Shares, Issued Common stock, shares outstanding Common Stock, Shares, Outstanding Recorded Investment Impaired Financing Receivable, Recorded Investment Unpaid Principal Balance Impaired Financing Receivable, Unpaid Principal Balance Loans Receivable And Allowance For Credit Losses Financing Receivables [Text Block] FHLB Advances Schedule of Federal Home Loan Bank, Advances, by Branch of FHLB Bank [Table Text Block] Maturity of Borrowed Funds and Certificates of Deposit Schedule of Maturities of Long-term Debt [Table Text Block] Other than temporary impairments, amount Other than Temporary Impairment Losses, Investments Proceeds received from sale of AFS securities Proceeds from Sale of Debt Securities, Available-for-sale Gain on sale of AFS securities Available-for-sale Securities, Gross Realized Gains Number of Contracts Financing Receivable, Modifications, Subsequent Default, Number of Contracts Recorded Investment Financing Receivable, Modifications, Subsequent Default, Recorded Investment Summary Of Capital And Total Risk-Based Capital Ratios Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block] Summary Of Shares Held In The ESOP Trust Employee Stock Ownership Plan (ESOP) Disclosures [Table Text Block] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] AOCI [Member] AOCI Attributable to Parent [Member] Other Comprehensive Income Components [Axis] Other Comprehensive Income Location [Axis] Other Comprehensive Income Components [Domain] Other Comprehensive Income Location [Domain] Unrealized Gains (Losses) on AFS Securities [Member] Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] Unrealized Gains (Losses) on Cash Flow Hedges [Member] Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Beginning Balance Other comprehensive income (loss), before reclassifications OCI, before Reclassifications, Net of Tax, Attributable to Parent Amount reclassified from AOCI Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Reclassification of certain income tax effects related to adoption of ASU 2018-02 Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect Amount of increase (decrease) in accumulated other comprehensive income (AOCI) for reclassification to retained earnings of tax effect from remeasurement of deferred tax pursuant to Tax Cuts and Jobs Act. Ending Balance Interest-earning deposits Interest-bearing Deposits in Banks and Other Financial Institutions Available-for-sale securities, amortized cost Held-to-maturity securities, estimated fair value Loans receivable, allowance for credit losses Special Mention [Member] Special Mention [Member] Substandard [Member] Substandard [Member] Financing receivable, total recorded investment Fair Value Of Financial Instruments Fair Value Disclosures [Text Block] Public unit deposits Pledged Financial Instruments, Not Separately Reported, Securities for Public Unit Deposits The carrying amount as of the date of the latest financial statement presented of securities which are owned but transferred to serve as collateral for public unit deposits, and for which the transferee does not have the right by contract or custom to sell or re-pledge them to an unrelated party. Repurchase agreements Pledged Financial Instruments, Not Separately Reported, Securities for Repurchase Agreements FRB of Kansas City Pledged Financial Instruments, Not Separately Reported, Securities for Other Debt Facilities Total securities pledged as collateral Pledged Financial Instruments, Not Separately Reported, Securities Statement of Stockholders' Equity [Abstract] Cash dividends to stockholders Premises And Equipment, Net Property, Plant and Equipment Disclosure [Text Block] Common Stock [Member] Common Stock [Member] Additional Paid-In Capital [Member] Additional Paid-in Capital [Member] Unearned Compensation ESOP [Member] Employee Stock Ownership Plan [Member] A plan where shares of company stock are allocated to qualified employees based on the proportion of their qualifying compensation to total qualifying compensation. Funds are borrowed by the ESOP from the Company to purchase the Company's common stock and repaid from the Bank's contributions and dividends paid on unallocated ESOP shares. The shares pledged as collateral are reported as a reduction of stockholders' equity at cost. As ESOP shares are committed to be released from collateral each quarter, the Company records compensation expense based on the average market price of the Company's stock during the quarter. Additionally, the shares become outstanding for earnings per share ("EPS") computations once they are committed to be released. Retained Earnings [Member] Retained Earnings [Member] Balance Other comprehensive income (loss), net of tax Reclassification of certain tax effects related to adoption of Accounting Standards Update (ASU) 2018-02 Cumulative effect of adopting ASU 2016-09 Cumulative Effect on Retained Earnings, Net of Tax Capital City Bancshares, Inc. (CCB) acquisition Stock Issued During Period, Value, Acquisitions ESOP activity Stock Issued During Period, Value, Employee Stock Ownership Plan Restricted stock activity, net Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Stock-based compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Stock options exercised Stock Issued During Period, Value, Stock Options Exercised Cash dividends to stockholders Dividends, Cash Balance Schedule Of Fair Value Assets Measured On A Recurring Basis Fair Value, Assets Measured on Recurring Basis [Table Text Block] Schedule Of Carrying Amounts And Estimated Fair Values Of Financial Instruments Fair Value, by Balance Sheet Grouping [Table Text Block] Deposits and Borrowed Funds Debt Disclosure [Text Block] Allocated ESOP shares Employee Stock Ownership Plan (ESOP), Number of Allocated Shares Unreleased ESOP shares Employee Stock Ownership Plan (ESOP), Number of Suspense Shares Total ESOP shares Employee Stock Ownership Plan (ESOP), Shares in ESOP Fair value of unreleased ESOP shares Employee Stock Ownership Plan (ESOP), Deferred Shares, Fair Value Investments in Affordable Housing Projects [Abstract] Investment In affordable housing limited partnerships Investment In Affordable Housing Limited Partnerships The Bank's investment in low income housing partnerships Obligations related to investments in affordable housing limited partnerships Qualified Affordable Housing Project Investments, Commitment Affordable housing tax credits commitment, year to be paid Affordable Housing Tax Credits Commitment, Year to be Paid Proportional amortization expense, amount Amortization Method Qualified Affordable Housing Project Investments, Amortization Affordable housing tax credits, amount Affordable Housing Tax Credits and Other Tax Benefits, Amount Net income tax benefit, low income housing partnerships Net Income Tax Benefit, Low Income Housing Partnerships Amount of net income tax benefit recognized related to low income housing partnerships Impairment losses from the forfeiture or ineligibility of tax credits or other circumstances, amount Schedule Of Balance Sheets Condensed Balance Sheet [Table Text Block] Schedule Of Statements Of Income Condensed Income Statement [Table Text Block] Schedule Of Statements Of Cash Flows Condensed Cash Flow Statement [Table Text Block] Dividend income from the Bank Dividend Income From Bank Dividend income from bank subsidiary. Interest income from other investments Other Interest and Dividend Income INTEREST EXPENSE NON-INTEREST INCOME Other non-interest expense INCOME BEFORE INCOME TAX EXPENSE AND EQUITY IN EXCESS OF DISTRIBUTION OVER EARNINGS OF SUBSIDIARY INCOME TAX (BENEFIT) EXPENSE INCOME BEFORE EQUITY IN EXCESS OF DISTRIBUTION OVER EARNINGS OF SUBSIDIARY Income Before Equity In Undistributed Overdistributed Earnings Of Subsidiary Income before equity in undistributed (overdistributed) earnings of subsidiary. EQUITY IN EXCESS OF DISTRIBUTION OVER EARNINGS OF SUBSIDIARY Schedule Of Income Tax Expense Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Differences Between Effective Rates And Statutory Federal Income Tax Rate Computed On Income Before Income Tax Expense Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Deferred Income Tax Expense (Benefit) Results From Temporary Differences In Recognition Of Revenue And Expenses For Tax Summary of Deferred Tax Liability Not Recognized [Table Text Block] Components Of Net Deferred Income Tax Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Summary of Loans Receivable Summary Of Loans Receivable By Category [Table Text Block] Tabular disclosure of the various types of loans receivable and for each the gross carrying value as of the balance sheet date. Recorded Investment in Loans, Past Due Past Due Financing Receivables [Table Text Block] Recorded Investment in Loans, Nonaccrual Schedule of Financing Receivables, Non Accrual Status [Table Text Block] Recorded Investment in Classified Loans Financing Receivable Credit Quality Indicators [Table Text Block] Weighted Average Loan-to-Value and Credit Score Information Financing Receivable Credit Quality Indicator Loan To Value And Credit Scores [Table Text Block] Financing Receivable Credit Quality Indicator Loan To Value And Credit Scores Troubled Debt Restructurings on Financing Receivables Troubled Debt Restructurings on Financing Receivables [Table Text Block] Impaired Loans by Class Impaired Financing Receivables [Table Text Block] Allowance for Credit Losses Allowance for Credit Losses on Financing Receivables [Table Text Block] Business Combinations [Abstract] Regulatory and Outside Services [Member] Regulatory and Outside Services [Member] Primary financial statement caption encompassing regulatory and outside services Fair value of loans acquired Business Combination, Acquired Receivable, Fair Value Fair value of deposits acquired Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Deposits The fair value of customer deposits acquired in a business combination PCI loans, contractually required payments receivable at acquisition Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, Contractually Required Payments Receivable at Acquisition PCI loans, cash flows expected to be collected at acquisition Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, Cash Flows Expected to be Collected at Acquisition Number of common stock shares issued Business Acquisition, Equity Interest Issued or Issuable, Number of Shares Total merger consideration Business Combination, Consideration Transferred Closing stock price Business Acquisition, Share Price Merger-related expenses incurred Business Combination, Acquisition Related Costs Parent Company Financial Information (Parent Company Only) Condensed Financial Information of Parent Company Only Disclosure [Text Block] Financing Receivables, Period Past Due [Axis] Financing Receivables, Period Past Due [Axis] Financing Receivables, Period Past Due [Domain] Financing Receivables, Period Past Due [Domain] Financing Receivables, 30 to 89 Days Past Due [Member] Financing Receivables, 30 to 89 Days Past Due [Member] Financing receivables that are more than 29 days past due but fewer than 90 days past due. Financing Receivables, Equal to Greater than 90 Days Past Due [Member] Financing Receivables, Equal to Greater than 90 Days Past Due [Member] Financing receivable, total delinquent loans Financing Receivable, Recorded Investment, Past Due Financing receivable, current loans Financing Receivable, Recorded Investment, Current Income Taxes Income Tax Disclosure [Text Block] Description of Business Nature of Operations [Text Block] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Net Presentation of Cash Flows Related to Borrowings Net Presentation of Cash Flows Related to Borrowings [Policy Text Block] Disclosure of accounting policy for net presentation of cash flows related to borrowings Securities Investment, Policy [Policy Text Block] Loans Receivable Finance, Loan and Lease Receivables, Held-for-investment, Policy [Policy Text Block] Allowance for Credit Losses Loans and Leases Receivable, Allowance for Loan Losses Policy [Policy Text Block] Federal Home Loan Bank Stock Federal Home Loan Bank Stock [Policy Text Block] Federal Home Loan Bank Stock [Policy Text Block] Premises and Equipment Property, Plant and Equipment, Policy [Policy Text Block] Other Assets Goodwill and Intangible Assets, Policy [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Employee Stock Ownership Plan Employee Stock Ownership Plan (ESOP), Policy [Policy Text Block] Stock-based Compensation Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Borrowed Funds Borrowed Funds [Policy Text Block] Borrowed Funds [Policy Text Block] Segment Information Segment Reporting, Policy [Policy Text Block] Low Income Housing Partnerships Low Income Housing Partnerships, Policy [Policy Text Block] Disclosure of accounting policy for low income housing partnerships Earnings Per Share Earnings Per Share, Policy [Policy Text Block] Trust Asset Management Trust Asset Management [Policy Text Block] The accounting policy for treatment of trust assets Comprehensive Income Comprehensive Income, Policy [Policy Text Block] Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Average Recorded Investment, No Related Allowance Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment Average Recorded Investment, Allowance Recorded Impaired Financing Receivable, with Related Allowance, Average Recorded Investment Average Recorded Investment Impaired Financing Receivable, Average Recorded Investment Interest Income Recognized, No Related Allowance Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method Interest Income Recognized, Allowance Recorded Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method Interest Income Recognized Impaired Financing Receivable, Interest Income, Accrual Method Document And Entity Information [Abstract] Document and entity information [Abstract] Entity Registrant Name Entity Registrant Name Trading Symbol Trading Symbol Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding 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 Public Float Entity Public Float Summary Of Significant Accounting Policies Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block] Securities Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Low Income Housing Partnerships Affordable Housing Program [Text Block] Acquisition Business Combination Disclosure [Text Block] Debt Securities [Member] Debt Securities [Member] Investment Holdings [Line Items] Investment Holdings [Line Items] Available-for-sale Securities, One year or less, Amortized Cost Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, within One Year, Amortized Cost