3.20.2 html 925 463 1 true 106 0 false 4 false false R1.htm 000010 - Document - Document and Entity Information Sheet http://www.greatsouthernbank.com/20200630/role/idr_DocumentDocumentAndEntityInformation Document and Entity Information Cover 1 false false R2.htm 000020 - Statement - CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Unaudited) Sheet http://www.greatsouthernbank.com/20200630/role/idr_CONSOLIDATEDSTATEMENTSOFFINANCIALCONDITIONUnaudited CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Unaudited) Statements 2 false false R3.htm 000030 - Statement - CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Unaudited) - Parenthetical Sheet http://www.greatsouthernbank.com/20200630/role/idr_CONSOLIDATEDSTATEMENTSOFFINANCIALCONDITIONUnauditedParenthetical CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Unaudited) - Parenthetical Statements 3 false false R4.htm 000040 - Statement - CONSOLIDATED STATEMENTS OF INCOME (Unaudited) Sheet http://www.greatsouthernbank.com/20200630/role/idr_CONSOLIDATEDSTATEMENTSOFINCOMEUnaudited CONSOLIDATED STATEMENTS OF INCOME (Unaudited) Statements 4 false false R5.htm 000050 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) Sheet http://www.greatsouthernbank.com/20200630/role/idr_CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOMEUnaudited CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) Statements 5 false false R6.htm 000060 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - Parenthetical Sheet http://www.greatsouthernbank.com/20200630/role/idr_CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOMEUnauditedParenthetical CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - Parenthetical Statements 6 false false R7.htm 000070 - Statement - CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) Sheet http://www.greatsouthernbank.com/20200630/role/idr_CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITYUnaudited CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) Statements 7 false false R8.htm 000080 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) Sheet http://www.greatsouthernbank.com/20200630/role/idr_CONSOLIDATEDSTATEMENTSOFCASHFLOWSUnaudited CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) Statements 8 false false R9.htm 000090 - Disclosure - NOTE 1: BASIS OF PRESENTATION Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE1BASISOFPRESENTATION NOTE 1: BASIS OF PRESENTATION Notes 9 false false R10.htm 000100 - Disclosure - NOTE 2: NATURE OF OPERATIONS AND OPERATING SEGMENTS Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE2NATUREOFOPERATIONSANDOPERATINGSEGMENTS NOTE 2: NATURE OF OPERATIONS AND OPERATING SEGMENTS Notes 10 false false R11.htm 000110 - Disclosure - NOTE 3: RECENT ACCOUNTING PRONOUNCEMENTS Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE3RECENTACCOUNTINGPRONOUNCEMENTS NOTE 3: RECENT ACCOUNTING PRONOUNCEMENTS Notes 11 false false R12.htm 000120 - Disclosure - NOTE 4: EARNINGS PER SHARE Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE4EARNINGSPERSHARE NOTE 4: EARNINGS PER SHARE Notes 12 false false R13.htm 000130 - Disclosure - NOTE 5: INVESTMENT SECURITIES Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE5INVESTMENTSECURITIES NOTE 5: INVESTMENT SECURITIES Notes 13 false false R14.htm 000140 - Disclosure - NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSES NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES Notes 14 false false R15.htm 000150 - Disclosure - NOTE 7: ACQUIRED LOANS, LOSS SHARING AGREEMENTS AND FDIC INDEMNIFICATION ASSETS Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE7ACQUIREDLOANSLOSSSHARINGAGREEMENTSANDFDICINDEMNIFICATIONASSETS NOTE 7: ACQUIRED LOANS, LOSS SHARING AGREEMENTS AND FDIC INDEMNIFICATION ASSETS Notes 15 false false R16.htm 000160 - Disclosure - Note 8: Other Real Estate Owned Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote8OtherRealEstateOwned Note 8: Other Real Estate Owned Notes 16 false false R17.htm 000170 - Disclosure - Note 9: Premises and Equipment Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote9PremisesAndEquipment Note 9: Premises and Equipment Notes 17 false false R18.htm 000180 - Disclosure - Note 10: Deposits Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote10Deposits Note 10: Deposits Notes 18 false false R19.htm 000190 - Disclosure - Note 11: Advances From Federal Home Loan Bank Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote11AdvancesFromFederalHomeLoanBank Note 11: Advances From Federal Home Loan Bank Notes 19 false false R20.htm 000200 - Disclosure - Note 12: Securities Sold Under Reverse Repurchase Agreements and Short-term Borrowings Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote12SecuritiesSoldUnderReverseRepurchaseAgreementsAndShortTermBorrowings Note 12: Securities Sold Under Reverse Repurchase Agreements and Short-term Borrowings Notes 20 false false R21.htm 000210 - Disclosure - Note 13: Subordinated Notes Notes http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote13SubordinatedNotes Note 13: Subordinated Notes Notes 21 false false R22.htm 000220 - Disclosure - Note 14: Income Taxes Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote14IncomeTaxes Note 14: Income Taxes Notes 22 false false R23.htm 000230 - Disclosure - Note 15: Disclosures About Fair Value of Financial Instruments Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote15DisclosuresAboutFairValueOfFinancialInstruments Note 15: Disclosures About Fair Value of Financial Instruments Notes 23 false false R24.htm 000240 - Disclosure - Note 16: Derivatives and Hedging Activities Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote16DerivativesAndHedgingActivities Note 16: Derivatives and Hedging Activities Notes 24 false false R25.htm 000250 - Disclosure - NOTE 1: BASIS OF PRESENTATION: Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE1BASISOFPRESENTATIONOrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesPolicies NOTE 1: BASIS OF PRESENTATION: Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies (Policies) Policies 25 false false R26.htm 000260 - Disclosure - NOTE 2: NATURE OF OPERATIONS AND OPERATING SEGMENTS: Segment Reporting, Policy (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE2NATUREOFOPERATIONSANDOPERATINGSEGMENTSSegmentReportingPolicyPolicies NOTE 2: NATURE OF OPERATIONS AND OPERATING SEGMENTS: Segment Reporting, Policy (Policies) Policies 26 false false R27.htm 000270 - Disclosure - NOTE 4: EARNINGS PER SHARE: Earnings Per Share, Policy (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE4EARNINGSPERSHAREEarningsPerSharePolicyPolicies NOTE 4: EARNINGS PER SHARE: Earnings Per Share, Policy (Policies) Policies 27 false false R28.htm 000280 - Disclosure - NOTE 5: INVESTMENT SECURITIES: Investment, Policy (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE5INVESTMENTSECURITIESInvestmentPolicyPolicies NOTE 5: INVESTMENT SECURITIES: Investment, Policy (Policies) Policies 28 false false R29.htm 000290 - Disclosure - NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Loan Portfolio Credit Quality Internal Grading System Policy (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESLoanPortfolioCreditQualityInternalGradingSystemPolicyPolicies NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Loan Portfolio Credit Quality Internal Grading System Policy (Policies) Policies 29 false false R30.htm 000300 - Disclosure - NOTE 7: ACQUIRED LOANS, LOSS SHARING AGREEMENTS AND FDIC INDEMNIFICATION ASSETS: Business Combinations Policy (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE7ACQUIREDLOANSLOSSSHARINGAGREEMENTSANDFDICINDEMNIFICATIONASSETSBusinessCombinationsPolicyPolicies NOTE 7: ACQUIRED LOANS, LOSS SHARING AGREEMENTS AND FDIC INDEMNIFICATION ASSETS: Business Combinations Policy (Policies) Policies 30 false false R31.htm 000310 - Disclosure - NOTE 7: ACQUIRED LOANS, LOSS SHARING AGREEMENTS AND FDIC INDEMNIFICATION ASSETS: Business Acquisition Fair Value and Expected Cash Flows Policy (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE7ACQUIREDLOANSLOSSSHARINGAGREEMENTSANDFDICINDEMNIFICATIONASSETSBusinessAcquisitionFairValueAndExpectedCashFlowsPolicyPolicies NOTE 7: ACQUIRED LOANS, LOSS SHARING AGREEMENTS AND FDIC INDEMNIFICATION ASSETS: Business Acquisition Fair Value and Expected Cash Flows Policy (Policies) Policies 31 false false R32.htm 000320 - Disclosure - Note 9: Premises and Equipment: Lessee, Operating Lease, Disclosure (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote9PremisesAndEquipmentLesseeOperatingLeaseDisclosurePolicies Note 9: Premises and Equipment: Lessee, Operating Lease, Disclosure (Policies) Policies 32 false false R33.htm 000330 - Disclosure - Note 14: Income Taxes: Income Tax, Policy (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote14IncomeTaxesIncomeTaxPolicyPolicies Note 14: Income Taxes: Income Tax, Policy (Policies) Policies 33 false false R34.htm 000340 - Disclosure - Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Measurement, Policy (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote15DisclosuresAboutFairValueOfFinancialInstrumentsFairValueMeasurementPolicyPolicies Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Measurement, Policy (Policies) Policies 34 false false R35.htm 000350 - Disclosure - Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Loans Held for Sale Policy (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote15DisclosuresAboutFairValueOfFinancialInstrumentsFairValueLoansHeldForSalePolicyPolicies Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Loans Held for Sale Policy (Policies) Policies 35 false false R36.htm 000360 - Disclosure - Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Impaired Loans Policy (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote15DisclosuresAboutFairValueOfFinancialInstrumentsFairValueImpairedLoansPolicyPolicies Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Impaired Loans Policy (Policies) Policies 36 false false R37.htm 000370 - Disclosure - Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Foreclosed Assets Held for Sale Policy (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote15DisclosuresAboutFairValueOfFinancialInstrumentsFairValueForeclosedAssetsHeldForSalePolicyPolicies Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Foreclosed Assets Held for Sale Policy (Policies) Policies 37 false false R38.htm 000380 - Disclosure - Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Financial Instruments Policy (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote15DisclosuresAboutFairValueOfFinancialInstrumentsFairValueFinancialInstrumentsPolicyPolicies Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Financial Instruments Policy (Policies) Policies 38 false false R39.htm 000390 - Disclosure - Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Cash and Cash Equivalents and Federal home Loan Bank Stock Policy (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote15DisclosuresAboutFairValueOfFinancialInstrumentsFairValueCashAndCashEquivalentsAndFederalHomeLoanBankStockPolicyPolicies Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Cash and Cash Equivalents and Federal home Loan Bank Stock Policy (Policies) Policies 39 false false R40.htm 000400 - Disclosure - Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Loans and Interest Receivable Policy (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote15DisclosuresAboutFairValueOfFinancialInstrumentsFairValueLoansAndInterestReceivablePolicyPolicies Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Loans and Interest Receivable Policy (Policies) Policies 40 false false R41.htm 000410 - Disclosure - Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Deposits and Accrued Interest Payable Policy (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote15DisclosuresAboutFairValueOfFinancialInstrumentsFairValueDepositsAndAccruedInterestPayablePolicyPolicies Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Deposits and Accrued Interest Payable Policy (Policies) Policies 41 false false R42.htm 000420 - Disclosure - Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Short Term Borrowings Policy (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote15DisclosuresAboutFairValueOfFinancialInstrumentsFairValueShortTermBorrowingsPolicyPolicies Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Short Term Borrowings Policy (Policies) Policies 42 false false R43.htm 000430 - Disclosure - Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Subordinated Debentures Policy (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote15DisclosuresAboutFairValueOfFinancialInstrumentsFairValueSubordinatedDebenturesPolicyPolicies Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Subordinated Debentures Policy (Policies) Policies 43 false false R44.htm 000440 - Disclosure - Note 15: Disclosures About Fair Value of Financial Instruments: Subordinated Notes Policy (Policies) Notes http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote15DisclosuresAboutFairValueOfFinancialInstrumentsSubordinatedNotesPolicyPolicies Note 15: Disclosures About Fair Value of Financial Instruments: Subordinated Notes Policy (Policies) Policies 44 false false R45.htm 000450 - Disclosure - Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Commitments to Originate Loans, Letters of Credit and Lines of Credit Policy (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote15DisclosuresAboutFairValueOfFinancialInstrumentsFairValueCommitmentsToOriginateLoansLettersOfCreditAndLinesOfCreditPolicyPolicies Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value Commitments to Originate Loans, Letters of Credit and Lines of Credit Policy (Policies) Policies 45 false false R46.htm 000460 - Disclosure - Note 16: Derivatives and Hedging Activities: Risk Management Objective of Using Derivatives (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote16DerivativesAndHedgingActivitiesRiskManagementObjectiveOfUsingDerivativesPolicies Note 16: Derivatives and Hedging Activities: Risk Management Objective of Using Derivatives (Policies) Policies 46 false false R47.htm 000470 - Disclosure - Note 16: Derivatives and Hedging Activities: Nondesignated Hedges (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote16DerivativesAndHedgingActivitiesNondesignatedHedgesPolicies Note 16: Derivatives and Hedging Activities: Nondesignated Hedges (Policies) Policies 47 false false R48.htm 000480 - Disclosure - Note 16: Derivatives and Hedging Activities: Cash Flow Hedges (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote16DerivativesAndHedgingActivitiesCashFlowHedgesPolicies Note 16: Derivatives and Hedging Activities: Cash Flow Hedges (Policies) Policies 48 false false R49.htm 000490 - Disclosure - Note 16: Derivatives and Hedging Activities: Agreements with Derivative Counterparties (Policies) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote16DerivativesAndHedgingActivitiesAgreementsWithDerivativeCounterpartiesPolicies Note 16: Derivatives and Hedging Activities: Agreements with Derivative Counterparties (Policies) Policies 49 false false R50.htm 000500 - Disclosure - NOTE 4: EARNINGS PER SHARE: Schedule of Earnings Per Share, Basic and Diluted (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE4EARNINGSPERSHAREScheduleOfEarningsPerShareBasicAndDilutedTables NOTE 4: EARNINGS PER SHARE: Schedule of Earnings Per Share, Basic and Diluted (Tables) Tables 50 false false R51.htm 000510 - Disclosure - NOTE 5: INVESTMENT SECURITIES: Investment Securities (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE5INVESTMENTSECURITIESInvestmentSecuritiesTables NOTE 5: INVESTMENT SECURITIES: Investment Securities (Tables) Tables 51 false false R52.htm 000520 - Disclosure - NOTE 5: INVESTMENT SECURITIES: Investments Classified by Contractual Maturity Date (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE5INVESTMENTSECURITIESInvestmentsClassifiedByContractualMaturityDateTables NOTE 5: INVESTMENT SECURITIES: Investments Classified by Contractual Maturity Date (Tables) Tables 52 false false R53.htm 000530 - Disclosure - NOTE 5: INVESTMENT SECURITIES: Unrealized Gain (Loss) on Investments (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE5INVESTMENTSECURITIESUnrealizedGainLossOnInvestmentsTables NOTE 5: INVESTMENT SECURITIES: Unrealized Gain (Loss) on Investments (Tables) Tables 53 false false R54.htm 000540 - Disclosure - NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Schedule of Accounts, Notes, Loans and Financing Receivable (Tables) Notes http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESScheduleOfAccountsNotesLoansAndFinancingReceivableTables NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Schedule of Accounts, Notes, Loans and Financing Receivable (Tables) Tables 54 false false R55.htm 000550 - Disclosure - NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Schedule of Loans Classified by Aging Analysis (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESScheduleOfLoansClassifiedByAgingAnalysisTables NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Schedule of Loans Classified by Aging Analysis (Tables) Tables 55 false false R56.htm 000560 - Disclosure - NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Financing Receivable, Nonaccrual (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESFinancingReceivableNonaccrualTables NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Financing Receivable, Nonaccrual (Tables) Tables 56 false false R57.htm 000570 - Disclosure - NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Financing Receivable, Allowance for Credit Loss (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESFinancingReceivableAllowanceForCreditLossTables NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Financing Receivable, Allowance for Credit Loss (Tables) Tables 57 false false R58.htm 000580 - Disclosure - NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Impaired Financing Receivables (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESImpairedFinancingReceivablesTables NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Impaired Financing Receivables (Tables) Tables 58 false false R59.htm 000590 - Disclosure - NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Financing Receivable, Troubled Debt Restructuring (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESFinancingReceivableTroubledDebtRestructuringTables NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Financing Receivable, Troubled Debt Restructuring (Tables) Tables 59 false false R60.htm 000600 - Disclosure - NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Financing Receivable Credit Quality Indicators (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESFinancingReceivableCreditQualityIndicatorsTables NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Financing Receivable Credit Quality Indicators (Tables) Tables 60 false false R61.htm 000610 - Disclosure - NOTE 7: ACQUIRED LOANS, LOSS SHARING AGREEMENTS AND FDIC INDEMNIFICATION ASSETS: FDIC Indemnification Asset Policy (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE7ACQUIREDLOANSLOSSSHARINGAGREEMENTSANDFDICINDEMNIFICATIONASSETSFDICIndemnificationAssetPolicyTables NOTE 7: ACQUIRED LOANS, LOSS SHARING AGREEMENTS AND FDIC INDEMNIFICATION ASSETS: FDIC Indemnification Asset Policy (Tables) Tables 61 false false R62.htm 000620 - Disclosure - NOTE 7: ACQUIRED LOANS, LOSS SHARING AGREEMENTS AND FDIC INDEMNIFICATION ASSETS: Schedule of Impact of Adjustments of Acquired Loans on Financial Results (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE7ACQUIREDLOANSLOSSSHARINGAGREEMENTSANDFDICINDEMNIFICATIONASSETSScheduleOfImpactOfAdjustmentsOfAcquiredLoansOnFinancialResultsTables NOTE 7: ACQUIRED LOANS, LOSS SHARING AGREEMENTS AND FDIC INDEMNIFICATION ASSETS: Schedule of Impact of Adjustments of Acquired Loans on Financial Results (Tables) Tables 62 false false R63.htm 000630 - Disclosure - NOTE 7: ACQUIRED LOANS, LOSS SHARING AGREEMENTS AND FDIC INDEMNIFICATION ASSETS: Schedule of Accretable Yield Changes for Acquired Loans (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE7ACQUIREDLOANSLOSSSHARINGAGREEMENTSANDFDICINDEMNIFICATIONASSETSScheduleOfAccretableYieldChangesForAcquiredLoansTables NOTE 7: ACQUIRED LOANS, LOSS SHARING AGREEMENTS AND FDIC INDEMNIFICATION ASSETS: Schedule of Accretable Yield Changes for Acquired Loans (Tables) Tables 63 false false R64.htm 000640 - Disclosure - Note 8: Other Real Estate Owned: Schedule of Major Classifications of Foreclosed Assets (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote8OtherRealEstateOwnedScheduleOfMajorClassificationsOfForeclosedAssetsTables Note 8: Other Real Estate Owned: Schedule of Major Classifications of Foreclosed Assets (Tables) Tables 64 false false R65.htm 000650 - Disclosure - Note 8: Other Real Estate Owned: Schedule of Expenses Applicable to Foreclosed Assets (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote8OtherRealEstateOwnedScheduleOfExpensesApplicableToForeclosedAssetsTables Note 8: Other Real Estate Owned: Schedule of Expenses Applicable to Foreclosed Assets (Tables) Tables 65 false false R66.htm 000660 - Disclosure - Note 9: Premises and Equipment: Property, Plant and Equipment (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote9PremisesAndEquipmentPropertyPlantAndEquipmentTables Note 9: Premises and Equipment: Property, Plant and Equipment (Tables) Tables 66 false false R67.htm 000670 - Disclosure - Note 9: Premises and Equipment: Calculated Amount of Right of Use Assets and Lease Liabilities (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote9PremisesAndEquipmentCalculatedAmountOfRightOfUseAssetsAndLeaseLiabilitiesTables Note 9: Premises and Equipment: Calculated Amount of Right of Use Assets and Lease Liabilities (Tables) Tables 67 false false R68.htm 000680 - Disclosure - Note 9: Premises and Equipment: Schedule of Future Minimum Rental Payments for Operating Leases (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote9PremisesAndEquipmentScheduleOfFutureMinimumRentalPaymentsForOperatingLeasesTables Note 9: Premises and Equipment: Schedule of Future Minimum Rental Payments for Operating Leases (Tables) Tables 68 false false R69.htm 000690 - Disclosure - Note 10: Deposits: Schedule of Deposit Liabilities (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote10DepositsScheduleOfDepositLiabilitiesTables Note 10: Deposits: Schedule of Deposit Liabilities (Tables) Tables 69 false false R70.htm 000700 - Disclosure - Note 12: Securities Sold Under Reverse Repurchase Agreements and Short-term Borrowings: Schedule of Short-term Debt (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote12SecuritiesSoldUnderReverseRepurchaseAgreementsAndShortTermBorrowingsScheduleOfShortTermDebtTables Note 12: Securities Sold Under Reverse Repurchase Agreements and Short-term Borrowings: Schedule of Short-term Debt (Tables) Tables 70 false false R71.htm 000710 - Disclosure - Note 12: Securities Sold Under Reverse Repurchase Agreements and Short-term Borrowings: Schedule of Repurchase Agreements (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote12SecuritiesSoldUnderReverseRepurchaseAgreementsAndShortTermBorrowingsScheduleOfRepurchaseAgreementsTables Note 12: Securities Sold Under Reverse Repurchase Agreements and Short-term Borrowings: Schedule of Repurchase Agreements (Tables) Tables 71 false false R72.htm 000720 - Disclosure - Note 13: Subordinated Notes: Schedule of Subordinated Borrowing (Tables) Notes http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote13SubordinatedNotesScheduleOfSubordinatedBorrowingTables Note 13: Subordinated Notes: Schedule of Subordinated Borrowing (Tables) Tables 72 false false R73.htm 000730 - Disclosure - Note 14: Income Taxes: Schedule of Effective Income Tax Rate Reconciliation (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote14IncomeTaxesScheduleOfEffectiveIncomeTaxRateReconciliationTables Note 14: Income Taxes: Schedule of Effective Income Tax Rate Reconciliation (Tables) Tables 73 false false R74.htm 000740 - Disclosure - Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value, Assets Measured on Recurring Basis (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote15DisclosuresAboutFairValueOfFinancialInstrumentsFairValueAssetsMeasuredOnRecurringBasisTables Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value, Assets Measured on Recurring Basis (Tables) Tables 74 false false R75.htm 000750 - Disclosure - Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value, Assets and Liabilities Measured on Nonrecurring Basis (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote15DisclosuresAboutFairValueOfFinancialInstrumentsFairValueAssetsAndLiabilitiesMeasuredOnNonrecurringBasisTables Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value, Assets and Liabilities Measured on Nonrecurring Basis (Tables) Tables 75 false false R76.htm 000760 - Disclosure - Note 15: Disclosures About Fair Value of Financial Instruments: Schedule Of Financial Instruments Fair Value (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote15DisclosuresAboutFairValueOfFinancialInstrumentsScheduleOfFinancialInstrumentsFairValueTables Note 15: Disclosures About Fair Value of Financial Instruments: Schedule Of Financial Instruments Fair Value (Tables) Tables 76 false false R77.htm 000770 - Disclosure - Note 16: Derivatives and Hedging Activities: Schedule of Derivative Instruments in Statement of Financial Position, Fair Value (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote16DerivativesAndHedgingActivitiesScheduleOfDerivativeInstrumentsInStatementOfFinancialPositionFairValueTables Note 16: Derivatives and Hedging Activities: Schedule of Derivative Instruments in Statement of Financial Position, Fair Value (Tables) Tables 77 false false R78.htm 000780 - Disclosure - Note 16: Derivatives and Hedging Activities: Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss) (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote16DerivativesAndHedgingActivitiesScheduleOfDerivativeInstrumentsEffectOnOtherComprehensiveIncomeLossTables Note 16: Derivatives and Hedging Activities: Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss) (Tables) Tables 78 false false R79.htm 000790 - Disclosure - Note 16: Derivatives and Hedging Activities: Schedule of Derivative Instruments, Effect on Statements of Operations (Tables) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote16DerivativesAndHedgingActivitiesScheduleOfDerivativeInstrumentsEffectOnStatementsOfOperationsTables Note 16: Derivatives and Hedging Activities: Schedule of Derivative Instruments, Effect on Statements of Operations (Tables) Tables 79 false false R80.htm 000800 - Disclosure - NOTE 4: EARNINGS PER SHARE: Schedule of Earnings Per Share, Basic and Diluted (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE4EARNINGSPERSHAREScheduleOfEarningsPerShareBasicAndDilutedDetails NOTE 4: EARNINGS PER SHARE: Schedule of Earnings Per Share, Basic and Diluted (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE4EARNINGSPERSHAREScheduleOfEarningsPerShareBasicAndDilutedTables 80 false false R81.htm 000810 - Disclosure - NOTE 4: EARNINGS PER SHARE: Earnings Per Share, Policy (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE4EARNINGSPERSHAREEarningsPerSharePolicyDetails NOTE 4: EARNINGS PER SHARE: Earnings Per Share, Policy (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE4EARNINGSPERSHAREEarningsPerSharePolicyPolicies 81 false false R82.htm 000820 - Disclosure - NOTE 5: INVESTMENT SECURITIES: Investment Securities (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE5INVESTMENTSECURITIESInvestmentSecuritiesDetails NOTE 5: INVESTMENT SECURITIES: Investment Securities (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE5INVESTMENTSECURITIESInvestmentSecuritiesTables 82 false false R83.htm 000830 - Disclosure - NOTE 5: INVESTMENT SECURITIES: Investments Classified by Contractual Maturity Date (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE5INVESTMENTSECURITIESInvestmentsClassifiedByContractualMaturityDateDetails NOTE 5: INVESTMENT SECURITIES: Investments Classified by Contractual Maturity Date (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE5INVESTMENTSECURITIESInvestmentsClassifiedByContractualMaturityDateTables 83 false false R84.htm 000840 - Disclosure - NOTE 5: INVESTMENT SECURITIES: Investment, Policy (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE5INVESTMENTSECURITIESInvestmentPolicyDetails NOTE 5: INVESTMENT SECURITIES: Investment, Policy (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE5INVESTMENTSECURITIESInvestmentSecuritiesTables 84 false false R85.htm 000850 - Disclosure - NOTE 5: INVESTMENT SECURITIES: Unrealized Gain (Loss) on Investments (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE5INVESTMENTSECURITIESUnrealizedGainLossOnInvestmentsDetails NOTE 5: INVESTMENT SECURITIES: Unrealized Gain (Loss) on Investments (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE5INVESTMENTSECURITIESUnrealizedGainLossOnInvestmentsTables 85 false false R86.htm 000860 - Disclosure - NOTE 5: INVESTMENT SECURITIES: Sales of Available for Sale Securities (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE5INVESTMENTSECURITIESSalesOfAvailableForSaleSecuritiesDetails NOTE 5: INVESTMENT SECURITIES: Sales of Available for Sale Securities (Details) Details 86 false false R87.htm 000870 - Disclosure - NOTE 5: INVESTMENT SECURITIES: Other than temporary impairment securities (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE5INVESTMENTSECURITIESOtherThanTemporaryImpairmentSecuritiesDetails NOTE 5: INVESTMENT SECURITIES: Other than temporary impairment securities (Details) Details 87 false false R88.htm 000880 - Disclosure - NOTE 5: INVESTMENT SECURITIES: Credit Losses Recognized on Investments (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE5INVESTMENTSECURITIESCreditLossesRecognizedOnInvestmentsDetails NOTE 5: INVESTMENT SECURITIES: Credit Losses Recognized on Investments (Details) Details 88 false false R89.htm 000890 - Disclosure - NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Schedule of Accounts, Notes, Loans and Financing Receivable (Details) Notes http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESScheduleOfAccountsNotesLoansAndFinancingReceivableDetails NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Schedule of Accounts, Notes, Loans and Financing Receivable (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESScheduleOfAccountsNotesLoansAndFinancingReceivableTables 89 false false R90.htm 000900 - Disclosure - NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Schedule of Loans Classified by Aging Analysis (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESScheduleOfLoansClassifiedByAgingAnalysisDetails NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Schedule of Loans Classified by Aging Analysis (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESScheduleOfLoansClassifiedByAgingAnalysisTables 90 false false R91.htm 000910 - Disclosure - NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Financing Receivable, Nonaccrual (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESFinancingReceivableNonaccrualDetails NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Financing Receivable, Nonaccrual (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESFinancingReceivableNonaccrualTables 91 false false R92.htm 000920 - Disclosure - NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Financing Receivable, Allowance for Credit Loss (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESFinancingReceivableAllowanceForCreditLossDetails NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Financing Receivable, Allowance for Credit Loss (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESFinancingReceivableAllowanceForCreditLossTables 92 false false R93.htm 000930 - Disclosure - NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Impaired Financing Receivables (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESImpairedFinancingReceivablesDetails NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Impaired Financing Receivables (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESImpairedFinancingReceivablesTables 93 false false R94.htm 000940 - Disclosure - NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Impaired Loans Specific Valuation Allowance (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESImpairedLoansSpecificValuationAllowanceDetails NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Impaired Loans Specific Valuation Allowance (Details) Details 94 false false R95.htm 000950 - Disclosure - NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Financing Receivable, Troubled Debt Restructuring (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESFinancingReceivableTroubledDebtRestructuringDetails NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Financing Receivable, Troubled Debt Restructuring (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESFinancingReceivableTroubledDebtRestructuringTables 95 false false R96.htm 000960 - Disclosure - NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Loans Modified in Troubled Debt Restructurings by Segment (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESLoansModifiedInTroubledDebtRestructuringsBySegmentDetails NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Loans Modified in Troubled Debt Restructurings by Segment (Details) Details 96 false false R97.htm 000970 - Disclosure - NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Troubled Debt Restructured Loans Returned to Accrual Status (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESTroubledDebtRestructuredLoansReturnedToAccrualStatusDetails NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Troubled Debt Restructured Loans Returned to Accrual Status (Details) Details 97 false false R98.htm 000980 - Disclosure - NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESDetails NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESScheduleOfAccountsNotesLoansAndFinancingReceivableTables 98 false false R99.htm 000990 - Disclosure - NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Financing Receivable Credit Quality Indicators (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESFinancingReceivableCreditQualityIndicatorsDetails NOTE 6: LOANS AND ALLOWANCE FOR LOAN LOSSES: Financing Receivable Credit Quality Indicators (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE6LOANSANDALLOWANCEFORLOANLOSSESFinancingReceivableCreditQualityIndicatorsTables 99 false false R100.htm 001000 - Disclosure - NOTE 7: ACQUIRED LOANS, LOSS SHARING AGREEMENTS AND FDIC INDEMNIFICATION ASSETS: FDIC Indemnification Asset Policy (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE7ACQUIREDLOANSLOSSSHARINGAGREEMENTSANDFDICINDEMNIFICATIONASSETSFDICIndemnificationAssetPolicyDetails NOTE 7: ACQUIRED LOANS, LOSS SHARING AGREEMENTS AND FDIC INDEMNIFICATION ASSETS: FDIC Indemnification Asset Policy (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE7ACQUIREDLOANSLOSSSHARINGAGREEMENTSANDFDICINDEMNIFICATIONASSETSFDICIndemnificationAssetPolicyTables 100 false false R101.htm 001010 - Disclosure - NOTE 7: ACQUIRED LOANS, LOSS SHARING AGREEMENTS AND FDIC INDEMNIFICATION ASSETS: Business Acquisition Fair Value and Expected Cash Flows Policy (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE7ACQUIREDLOANSLOSSSHARINGAGREEMENTSANDFDICINDEMNIFICATIONASSETSBusinessAcquisitionFairValueAndExpectedCashFlowsPolicyDetails NOTE 7: ACQUIRED LOANS, LOSS SHARING AGREEMENTS AND FDIC INDEMNIFICATION ASSETS: Business Acquisition Fair Value and Expected Cash Flows Policy (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE7ACQUIREDLOANSLOSSSHARINGAGREEMENTSANDFDICINDEMNIFICATIONASSETSBusinessAcquisitionFairValueAndExpectedCashFlowsPolicyPolicies 101 false false R102.htm 001020 - Disclosure - NOTE 7: ACQUIRED LOANS, LOSS SHARING AGREEMENTS AND FDIC INDEMNIFICATION ASSETS: Schedule of Impact of Adjustments of Acquired Loans on Financial Results (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE7ACQUIREDLOANSLOSSSHARINGAGREEMENTSANDFDICINDEMNIFICATIONASSETSScheduleOfImpactOfAdjustmentsOfAcquiredLoansOnFinancialResultsDetails NOTE 7: ACQUIRED LOANS, LOSS SHARING AGREEMENTS AND FDIC INDEMNIFICATION ASSETS: Schedule of Impact of Adjustments of Acquired Loans on Financial Results (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE7ACQUIREDLOANSLOSSSHARINGAGREEMENTSANDFDICINDEMNIFICATIONASSETSScheduleOfImpactOfAdjustmentsOfAcquiredLoansOnFinancialResultsTables 102 false false R103.htm 001030 - Disclosure - NOTE 7: ACQUIRED LOANS, LOSS SHARING AGREEMENTS AND FDIC INDEMNIFICATION ASSETS: Schedule of Accretable Yield Changes for Acquired Loans (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE7ACQUIREDLOANSLOSSSHARINGAGREEMENTSANDFDICINDEMNIFICATIONASSETSScheduleOfAccretableYieldChangesForAcquiredLoansDetails NOTE 7: ACQUIRED LOANS, LOSS SHARING AGREEMENTS AND FDIC INDEMNIFICATION ASSETS: Schedule of Accretable Yield Changes for Acquired Loans (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNOTE7ACQUIREDLOANSLOSSSHARINGAGREEMENTSANDFDICINDEMNIFICATIONASSETSScheduleOfAccretableYieldChangesForAcquiredLoansTables 103 false false R104.htm 001040 - Disclosure - Note 8: Other Real Estate Owned: Schedule of Major Classifications of Foreclosed Assets (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote8OtherRealEstateOwnedScheduleOfMajorClassificationsOfForeclosedAssetsDetails Note 8: Other Real Estate Owned: Schedule of Major Classifications of Foreclosed Assets (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote8OtherRealEstateOwnedScheduleOfMajorClassificationsOfForeclosedAssetsTables 104 false false R105.htm 001050 - Disclosure - Note 8: Other Real Estate Owned: Other Real Estate Owned Not Acquired Through Foreclosure (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote8OtherRealEstateOwnedOtherRealEstateOwnedNotAcquiredThroughForeclosureDetails Note 8: Other Real Estate Owned: Other Real Estate Owned Not Acquired Through Foreclosure (Details) Details 105 false false R106.htm 001060 - Disclosure - Note 8: Other Real Estate Owned: Loans in Process of Foreclosure (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote8OtherRealEstateOwnedLoansInProcessOfForeclosureDetails Note 8: Other Real Estate Owned: Loans in Process of Foreclosure (Details) Details 106 false false R107.htm 001070 - Disclosure - Note 8: Other Real Estate Owned: Schedule of Expenses Applicable to Foreclosed Assets (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote8OtherRealEstateOwnedScheduleOfExpensesApplicableToForeclosedAssetsDetails Note 8: Other Real Estate Owned: Schedule of Expenses Applicable to Foreclosed Assets (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote8OtherRealEstateOwnedScheduleOfExpensesApplicableToForeclosedAssetsTables 107 false false R108.htm 001080 - Disclosure - Note 9: Premises and Equipment: Property, Plant and Equipment (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote9PremisesAndEquipmentPropertyPlantAndEquipmentDetails Note 9: Premises and Equipment: Property, Plant and Equipment (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote9PremisesAndEquipmentPropertyPlantAndEquipmentTables 108 false false R109.htm 001090 - Disclosure - Note 9: Premises and Equipment: Lessee, Operating Lease, Disclosure: Lease Agreements (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote9PremisesAndEquipmentLesseeOperatingLeaseDisclosureLeaseAgreementsDetails Note 9: Premises and Equipment: Lessee, Operating Lease, Disclosure: Lease Agreements (Details) Details 109 false false R110.htm 001100 - Disclosure - Note 9: Premises and Equipment: Lessee, Operating Lease, Disclosure: Lease Expense Related to ATMs (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote9PremisesAndEquipmentLesseeOperatingLeaseDisclosureLeaseExpenseRelatedToATMsDetails Note 9: Premises and Equipment: Lessee, Operating Lease, Disclosure: Lease Expense Related to ATMs (Details) Details 110 false false R111.htm 001110 - Disclosure - Note 9: Premises and Equipment: Lessee, Operating Lease, Disclosure: Expected Lease Terms (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote9PremisesAndEquipmentLesseeOperatingLeaseDisclosureExpectedLeaseTermsDetails Note 9: Premises and Equipment: Lessee, Operating Lease, Disclosure: Expected Lease Terms (Details) Details 111 false false R112.htm 001120 - Disclosure - Note 9: Premises and Equipment: Calculated Amount of Right of Use Assets and Lease Liabilities (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote9PremisesAndEquipmentCalculatedAmountOfRightOfUseAssetsAndLeaseLiabilitiesDetails Note 9: Premises and Equipment: Calculated Amount of Right of Use Assets and Lease Liabilities (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote9PremisesAndEquipmentCalculatedAmountOfRightOfUseAssetsAndLeaseLiabilitiesTables 112 false false R113.htm 001130 - Disclosure - Note 9: Premises and Equipment: Operating Lease Expense (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote9PremisesAndEquipmentOperatingLeaseExpenseDetails Note 9: Premises and Equipment: Operating Lease Expense (Details) Details 113 false false R114.htm 001140 - Disclosure - Note 9: Premises and Equipment: Schedule of Future Minimum Rental Payments for Operating Leases (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote9PremisesAndEquipmentScheduleOfFutureMinimumRentalPaymentsForOperatingLeasesDetails Note 9: Premises and Equipment: Schedule of Future Minimum Rental Payments for Operating Leases (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote9PremisesAndEquipmentScheduleOfFutureMinimumRentalPaymentsForOperatingLeasesTables 114 false false R115.htm 001150 - Disclosure - Note 9: Premises and Equipment: Lessor Agreements (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote9PremisesAndEquipmentLessorAgreementsDetails Note 9: Premises and Equipment: Lessor Agreements (Details) Details 115 false false R116.htm 001160 - Disclosure - Note 10: Deposits: Schedule of Deposit Liabilities (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote10DepositsScheduleOfDepositLiabilitiesDetails Note 10: Deposits: Schedule of Deposit Liabilities (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote10DepositsScheduleOfDepositLiabilitiesTables 116 false false R117.htm 001170 - Disclosure - Note 11: Advances From Federal Home Loan Bank (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote11AdvancesFromFederalHomeLoanBankDetails Note 11: Advances From Federal Home Loan Bank (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote11AdvancesFromFederalHomeLoanBank 117 false false R118.htm 001180 - Disclosure - Note 12: Securities Sold Under Reverse Repurchase Agreements and Short-term Borrowings: Schedule of Short-term Debt (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote12SecuritiesSoldUnderReverseRepurchaseAgreementsAndShortTermBorrowingsScheduleOfShortTermDebtDetails Note 12: Securities Sold Under Reverse Repurchase Agreements and Short-term Borrowings: Schedule of Short-term Debt (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote12SecuritiesSoldUnderReverseRepurchaseAgreementsAndShortTermBorrowingsScheduleOfShortTermDebtTables 118 false false R119.htm 001190 - Disclosure - Note 12: Securities Sold Under Reverse Repurchase Agreements and Short-term Borrowings: Schedule of Repurchase Agreements (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote12SecuritiesSoldUnderReverseRepurchaseAgreementsAndShortTermBorrowingsScheduleOfRepurchaseAgreementsDetails Note 12: Securities Sold Under Reverse Repurchase Agreements and Short-term Borrowings: Schedule of Repurchase Agreements (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote12SecuritiesSoldUnderReverseRepurchaseAgreementsAndShortTermBorrowingsScheduleOfShortTermDebtTables 119 false false R120.htm 001200 - Disclosure - Note 13: Subordinated Notes: Subordinated Notes Details (Details) Notes http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote13SubordinatedNotesSubordinatedNotesDetailsDetails Note 13: Subordinated Notes: Subordinated Notes Details (Details) Details 120 false false R121.htm 001210 - Disclosure - Note 13: Subordinated Notes (Details) Notes http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote13SubordinatedNotesDetails Note 13: Subordinated Notes (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote13SubordinatedNotesScheduleOfSubordinatedBorrowingTables 121 false false R122.htm 001220 - Disclosure - Note 13: Subordinated Notes: Schedule of Subordinated Borrowing (Details) Notes http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote13SubordinatedNotesScheduleOfSubordinatedBorrowingDetails Note 13: Subordinated Notes: Schedule of Subordinated Borrowing (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote13SubordinatedNotesScheduleOfSubordinatedBorrowingTables 122 false false R123.htm 001230 - Disclosure - Note 14: Income Taxes: Schedule of Effective Income Tax Rate Reconciliation (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote14IncomeTaxesScheduleOfEffectiveIncomeTaxRateReconciliationDetails Note 14: Income Taxes: Schedule of Effective Income Tax Rate Reconciliation (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote14IncomeTaxesScheduleOfEffectiveIncomeTaxRateReconciliationTables 123 false false R124.htm 001240 - Disclosure - Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value, Assets Measured on Recurring Basis (Details) Sheet http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote15DisclosuresAboutFairValueOfFinancialInstrumentsFairValueAssetsMeasuredOnRecurringBasisDetails Note 15: Disclosures About Fair Value of Financial Instruments: Fair Value, Assets Measured on Recurring Basis (Details) Details http://www.greatsouthernbank.com/20200630/role/idr_DisclosureNote15DisclosuresAboutFairValueOfFinancialInstrumentsFairValueAssetsMeasuredOnRecurringBasisTables 124 false false R125.htm 001250 - 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