Accounting Policies [Abstract] Accounting Policies [Abstract] Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract] Loans: Accretion (Amortization) of Discounts and Premiums, Investments Amortization of available for sale securities, net Accretion and amortization of securities. Accretion And Amortization Of Securities Accretion & Amortization of Securities Accrued interest payable. Accrued Interest Payable Interest payable Accrued Interest Receivable And Other Assets Accrued Interest Receivable And Other Assets Accrued interest receivable Municipals Accrued Liabilities and Other Liabilities Accrued expenses and other liabilities Accrued Liabilities Accrued expenses Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Less: Accumulated depreciation Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive income (loss) AOCI Attributable to Parent [Member] Accumulated Other Comprehensive Income (Loss) [Member] Tabular disclosure of activities disclosure in allowance for credit losses. Activities In Allowance For Credit Losses [Table Text Block] Analysis of Allowance for Credit Losses Additional Cash Flow Elements, Investing Activities [Abstract] Activity in available for sale securities: Activity in securities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to net cash from operating activities: Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities: Advances from Federal Home Loan Banks Total Borrowings Federal Home Loan Bank (FHLB) Advances Federal Home Loan Bank (FHLB) Advances Federal Home Loan Bank advances Agricultural Loan [Member] Agricultural Loan [Member] Agricultural [Member] Agriculture Real Estate [Member] Agriculture Real Estate [Member] Agricultural Real Estate [Member] Allocated Share-based Compensation Expense Compensation expense Allowance For Credit Losses [Abstract] Allowance For Credit Losses [Abstract] ALLOWANCE FOR CREDIT LOSSES: Allowance For Credit Losses Relates To Unfunded Loan Commitments Allowance For Credit Losses Relates To Unfunded Loan Commitments Allowance for credit losses relates to unfunded loan commitments Allowance for Loan and Lease Losses [Roll Forward] Allowance for Loan Losses Allowance for Loan and Lease Losses, Write-offs Charge Offs Loans charged off Allowance for Loan and Lease Loss, Recovery of Bad Debts Recoveries Allowance is intended to reflect the potential for losses that may not be funded but for which the bank has made a commitment to fund including letters of credit. Allowance For Unfunded Loan Commitments And Letters Of Credit Allowance for Unfunded Loan Commitments & Letters of Credit Amendment Flag Amendment Flag Tabular disclosure of information pertaining to the amortization expense of the core deposit intangible assets remaining. Amortization Expense Of Core Deposit Intangible Asset [Table Text Block] Amortization Expense of Core Deposit Intangible Assets Amortization of Intangible Assets Amortization expense Amortization of core deposit intangible Amortization of Mortgage Servicing Rights (MSRs) Amortization of servicing rights Mortgage servicing rights amortization Amortized Cost and Fair Value Debt Securities [Abstract] Amortized Cost and Fair Value Debt Securities [Abstract] Amortized Cost and Fair Value Debt Securities [Abstract] Amortized over estimated remaining economic useful life of deposits term. Amortized Over Estimated Remaining Economic Useful Life Of Deposits Term Number of years amortized over an estimated remaining economic useful life of deposits Asset Impairment Charges Asset impairment charges Assets Total Assets Assets [Abstract] Assets Assets, Fair Value Adjustment Change in fair value of assets Assets, Fair Value Disclosure Fair Value Assets, Fair Value Disclosure [Abstract] Financial Assets: Assets, Fair Value Disclosure, Nonrecurring Assets measured at fair value on a nonrecurring basis, Total Assets Sold under Agreements to Repurchase [Line Items] Assets Sold under Agreements to Repurchase [Line Items] Repurchase Agreements and Similar Transactions, Maturity Periods [Domain] Repurchase Agreements and Similar Transactions, Maturity Periods [Domain] Repurchase Agreements and Similar Transactions, Maturity Periods [Axis] Repurchase Agreements and Similar Transactions, Maturity Periods [Axis] Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax Gross Unrealized Gains Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax Gross Unrealized Losses Available-for-sale Debt Securities, Amortized Cost Basis Amortized Cost Available for sale debt securities amortized cost basis excluding mortgage backed securities. Available For Sale Debt Securities Amortized Cost Basis Excluding Mortgage Backed Securities Amortized Cost, Total Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Gross Unrealized Losses, Twelve Months and Over Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Table Text Block] Gross Unrealized Losses, Aggregated by Investment Category and Length of Time Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Gross Unrealized Losses, Less Than Twelve Months Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value Fair Value, Less Than Twelve Months Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value Fair Value, Twelve Months and Over Available-for-sale Securities, Debt Maturities [Abstract] Available-for-sale Securities, Debt Maturities [Abstract] Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Amortized Cost Basis Amortized Cost, After five years through ten years Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value Fair Value, After five years through ten years Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis Amortized Cost, After one year through five years Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value Fair Value, After one year through five years Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis Amortized Cost, After ten years Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value Fair Value, After ten years Available for sale securities debt maturities fair value excluding mortgage backed securities. Available For Sale Securities Debt Maturities Fair Value Excluding Mortgage Backed Securities Fair Value, Total Available-for-sale Securities, Debt Maturities, Next Twelve Months, Amortized Cost Basis Amortized Cost, One year or less Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value Fair Value, One year or less Available-for-sale Securities, Debt Securities Ending Balance Beginning Balance Total Securities Available for Sale Fair Value Total, Fair Value Securities - available for sale Available-for-sale Securities, Gross Realized Gain (Loss), Disclosures [Abstract] Available-for-sale Securities, Gross Realized Gain (Loss), Disclosures [Abstract] Available-for-sale Securities, Gross Realized Gain (Loss) Gain on sales of available-for-sale securities Net realized gains Net gain on sale of available for sale securities Gain on Sale of Available for Sale Securities Gain on sales of available for sale securities Available for sale securities gross realized gain loss tax expenses. Available For Sale Securities Gross Realized Gain Loss Tax Expenses Tax expense related to net realized gains Available-for-sale Securities, Gross Realized Gains Gross realized gains Available-for-sale Securities, Gross Realized Losses Gross realized losses Available-for-sale Securities [Table Text Block] Amortized Cost and Fair Value of Securities with Gross Unrealized Gains and Losses Award Date [Axis] Award Date [Axis] Award Date [Domain] Award Date [Domain] Award Grants Originated In Period One [Member] Award Grants Originated In Period One [Member] Awards grants originated in 2012, 2013 and 2014 [Member] Award grants originated in period two. Award Grants Originated In Period Two [Member] Awards grants originated in 2013, 2014 and 2015 [Member] Award Type [Axis] Award Type [Axis] Banking and Thrift [Abstract] Banking and Thrift [Abstract] Bank Owned Life Insurance Bank Owned Life Insurance Brokers and Dealers [Abstract] Brokers and Dealers [Abstract] Building [Member] Buildings [Member] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition [Line Items] Business Acquisition [Line Items] Business Combination Disclosure [Text Block] Business Combination & Asset Purchase Business Combinations [Abstract] Business Combinations [Abstract] Capital Total Risk-Based Capital to Risk Weighted Assets Actual, Amount Capitalized service right assets fair market value. Capitalized Service Right Assets Fair Market Value Fair market value of the capitalized servicing rights Capitalized service right assets included in other assets. Capitalized Service Right Assets Included In Other Assets Capitalized service right assets included in other assets Capital Required for Capital Adequacy Total Risk-Based Capital to Risk Weighted Assets For Capital Adequacy Purposes, Amount Capital Required For Capital Adequacy To Risk Weighted Asset Capital Required For Capital Adequacy To Risk Weighted Asset Minimum ratio of capital to risk-weighted assets Capital Required for Capital Adequacy to Risk Weighted Assets Minimum ratio of capital to risk-weighted assets Total Risk-Based Capital to Risk Weighted Assets For Capital Adequacy Purposes, Ratio Capital required for capital adequacy to risk weighted assets including capital conservation buffer. Capital Required For Capital Adequacy To Risk Weighted Assets Including Capital Conservation Buffer Minimum ratio of capital to risk-weighted assets including capital conservation buffer Capital Required to be Well Capitalized Total Risk-Based Capital to Risk Weighted Assets To Be Well Capitalized Under the Prompt Corrective Action Provisions, Amount Capital Required to be Well Capitalized to Risk Weighted Assets Total Risk-Based Capital to Risk Weighted Assets To Be Well Capitalized Under the Prompt Corrective Action Provisions, Ratio Capital to Risk Weighted Assets Total Risk-Based Capital to Risk Weighted Assets Actual, Ratio Reported Value Measurement [Member] Reported Value Measurement [Member] Cash Cash Cash and Cash Equivalents [Abstract] Cash and Cash Equivalents Cash and Cash Equivalents, at Carrying Value Cash and Cash Equivalents - End of Year Cash and Cash Equivalents - Beginning of Year Cash and Cash Equivalents [Axis] Cash and Cash Equivalents [Axis] Cash and Cash Equivalents, Period Increase (Decrease) Net Change in Cash and Cash Equivalents Net Increase (Decrease) in Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Cash and Cash Equivalents Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Restrictions on Cash and Amounts Due from Banks Cash and Due from Banks Cash and due from banks Cash, Cash Equivalents, and Federal Funds Sold Cash and Cash Equivalents - End of Year Cash and Cash Equivalents - Beginning of Year Cash and Cash Equivalents Total cash and cash equivalents Cash Paid During Period [Abstract] Cash Paid During Period [Abstract] Cash paid during the year for: Certificates of Deposit [Member] Term CDs Sold Under Agreement to Repurchase [Member] Common Equity Tier 1 (CET1) as defined in the regulations. CET1 Common Equity Tier 1 Capital to Risk Weighted Assets Actual, Amount Changes In Assets And Liabilities [Abstract] Changes In Assets And Liabilities [Abstract] Changes in Assets and Liabilities: Class of Stock [Domain] Class of Stock [Domain] Commercial And Industrial And Industrial Development Bonds [Member] Commercial And Industrial And Industrial Development Bonds [Member] Commercial And Industrial and Industrial Development Bonds [Member] Commercial and Industrial Sector [Member] Commercial and Industrial [Member] Commercial Real Estate Portfolio Segment [Member] Commercial Real Estate [Member] Commitments and Contingencies Commitments and Contingencies Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Text Block] Off Balance Sheet Activities Commitments to Extend Credit [Member] Commitments to extend credit [Member] Common equity tier 1 capital required for capital adequacy. Common Equity Tier 1 Capital Required for Capital Adequacy Common Equity Tier 1 Capital For Capital Adequacy Purposes, Amount Common equity tier 1 capital required for capital adequacy to risk weighted assets. Common Equity Tier 1 Capital Required For Capital Adequacy To Risk Weighted Assets Common Equity Tier 1 Capital to Risk Weighted Assets For Capital Adequacy Purposes, Ratio Common equity tier 1 capital required to be well capitalized. Common Equity Tier 1 Capital Required To Be Well Capitalized Common Equity Tier 1 Capital to Risk Weighted Assets To Be Well Capitalized Under the Prompt Corrective Action Provisions, Amount Common equity tier 1 capital required to be well capitalized to risk weighted assets. Common Equity Tier 1 Capital Required To Be Well Capitalized To Risk Weighted Assets Common Equity Tier 1 Capital to Risk Weighted Assets To Be Well Capitalized Under the Prompt Corrective Action Provisions, Ratio Common equity Tier 1 (CET1) divided by risk weighted assets. Common Equity Tier1 to Risk Weighted Assets Common Equity Tier 1 Capital to Risk Weighted Assets Actual, Ratio Common equity tier one capital. Common Equity Tier One Capital [Member] Common Equity Tier 1 Capital [Member] Common Stock, Dividends, Per Share, Declared Cash dividends declared, per share Common Stock [Member] Common Stock [Member] Common Stock, Shares Authorized Common stock, shares authorized Common Stock, Shares, Issued Common stock, shares issued Common Stock, Shares, Outstanding Common stock, shares outstanding Common Stock, Value, Issued Common shares 6,500,000 shares 12/31/15 Common shares 10,000,000 shares 12/31/16 shares; issued & outstanding 5,200,000 shares Compensation and Retirement Disclosure [Abstract] Compensation and Retirement Disclosure [Abstract] Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] Components of Deferred Tax Assets [Abstract] Deferred Tax Assets: Deferred Tax Assets: Components of Deferred Tax Liabilities [Abstract] Deferred Tax Liabilities: Deferred Tax Liabilities: Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive Income Comprehensive Income, Policy [Policy Text Block] Other Comprehensive Income (Loss) Condensed Financial Information of Parent Company Only Disclosure [Abstract] Condensed Financial Information of Parent Company Only Disclosure [Abstract] Condensed Financial Information of Parent Company Only Disclosure [Text Block] Condensed Financial Statements of Parent Company Condensed Financial Statements, Captions [Line Items] Condensed Financial Statements, Captions [Line Items] Consolidation, Policy [Policy Text Block] Consolidation Policy Construction in Progress [Member] Construction in Progress [Member] Consumer Other Financing Receivables [Member] Consumer Other Financing Receivables [Member] Consumer - Other [Member] Consumer Portfolio Segment [Member] Consumer [Member] Tabular disclosure of contractual aging of the recorded investment in past due loans by class or loans. Contractual Aging Of Recorded Investment In Past Due Loans By Class Or Loans [Table Text Block] Contractual Aging of the Recorded Investment in Past Due Loans by Portfolio Classification of Loans Tabular disclosure of contribution provided by both the recoveries and the provision along with the reduction of the allowance caused by charge-off. Contribution Provided By Both Recoveries And Provision Along With Reduction Of Allowance Caused By Charge Offs [Table Text Block] Summary of Activities in Allowance for Credit Losses Credit Card Arrangements [Member] Credit Card Arrangements [Member] Credit card arrangements [Member] Credit Card Receivable [Member] Consumer - Credit Card [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Current Federal Tax Expense (Benefit) Federal Current Fiscal Year End Date Current Fiscal Year End Date Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Current: Custar [Member] Custar [Member] Custar [Member] Daily Securities [Member] Daily Securities [Member] Daily Securities Sold Under Agreement to Repurchase [Member] Deferred Federal Income Tax Expense (Benefit) Federal Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Deferred: Deferred Tax Liabilities, Gross Total deferred tax liabilities Total deferred tax liabilities Deferred Tax Assets, Gross Total deferred tax assets Total deferred tax assets Deferred Tax Assets, Net Net Deferred Tax Asset Deferred tax assets net unrealized gain on available for sale securities. Deferred Tax Assets Net Unrealized Gain On Available For Sale Securities Net unrealized gain on available- for-sale securities Net unrealized gain on available- for-sale securities Deferred Tax Assets, Other Other Other Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Provision for Loan Losses Allowance for loan losses Allowance for loan losses Deferred Tax Liabilities, Net Net Deferred Tax Liability Deferred Tax Liabilities Accreted Discounts On Bonds Deferred Tax Liabilities Accreted Discounts On Bonds Accreted discounts on bonds Accreted discounts on bonds Deferred Tax Liabilities FHLB Stock Dividends Deferred Tax Liabilities FHLB Stock Dividends FHLB stock dividends FHLB stock dividends Deferred Tax Liabilities, Mortgage Servicing Rights Mortgage servicing rights Mortgage servicing rights Deferred Tax Liabilities Net Unrealized Gain On Available For Sale Securities Deferred Tax Liabilities Net Unrealized Gain On Available For Sale Securities Net unrealized gain on available-for-sale securities Net unrealized gain on available-for-sale securities Deferred Tax Liabilities, Other Other Other Defined Contribution Plan, Employer Discretionary Contribution Amount Employer matching contribution and the discretionary contribution Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay Employee contribution matching percentage Defined Contribution Plan, Employers Matching Contribution, Annual Vesting Percentage Vesting percentage in participant's deferral contributions and employer matching contributions Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent Percentage of total eligible compensation, contribution by Bank, maximum limit Delinquent period for charging down commercial and agricultural credits. Delinquent Period For Charging Down Commercial And Agricultural Credits Delinquent period for charging down commercial and agricultural credits Delinquent period for charging down consumer loans Delinquent Period For Charging Down Consumer Loans Delinquent period for charging down consumer loans Delinquent Period Of Secured Consumer Loans Delinquent Period Of Secured Consumer Loans Days to charged consumer loans to the value of the collateral Deposit Liabilities Disclosures [Text Block] Deposits Deposits Total deposits Deposits [Abstract] Deposits Deposits, Negotiable Order of Withdrawal (NOW) NOW accounts Deposits, Savings Deposits Savings Depreciation Depreciation Expenses Depreciation, Nonproduction Depreciation Difference Between Related Party Deposit And Loan Lending Amount Difference Between Related Party Deposit And Loan Lending Amount Difference in related borrowings amounts Directors And Executive Officers [Member] Directors And Executive Officers [Member] Directors and Executive Officers [Member] Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Tabular disclosure of fixed rate loans and variable rate loans by major loan category. Distribution Of Fixed Rate Loans And Variable Rate Loans By Major Loan Category [Table Text Block] Distribution of Fixed Rate Loans and Variable Rate Loans by Major Loan Category Dividend And Accounts Receivable From Subsidiary Dividend And Accounts Receivable From Subsidiary Dividends & Accounts receivable from subsidiaries Dividend Income Operating From Bank Subsidiaries Dividend Income Operating From Bank Subsidiaries Dividends from subsidiaries Dividends, Common Stock, Cash Cash dividends declared - 0.84, 0.87 and 0.91 per share for the period ended 2014, 2015 and 2016 respectively Dividends May Be Paid Without Prior Regulatory Approval Dividends May Be Paid Without Prior Regulatory Approval Dividends may be paid without prior regulatory approval Dividends Payable Dividend payable Dividends payable Document And Entity Information [Abstract] Document And Entity Information [Abstract] Document And Entity Information [Abstract] Document Fiscal Period Focus Document Fiscal Period Focus Document Fiscal Year Focus Document Fiscal Year Focus Document Period End Date Document Period End Date Document Type Document Type Doubtful [Member] 7 [Member] Due from Related Parties, Unclassified [Abstract] Related party receivables: Earnings Per Share [Abstract] Earnings Per Share [Abstract] Earnings Per Share, Basic Earnings per common share Earnings Per Share, Basic and Diluted Basic and diluted earnings per share Earnings Per Share - Basic and Diluted Earnings Per Share, Policy [Policy Text Block] Earnings Per Share