Document And Entity Information Debt Instrument, Name [Domain] Shares issued for dividend reinvestment pursuant to the 2024 Dividend Reinvestment and Stock Purchase Plan (in shares) Stock Issued During Period, Shares, Dividend Reinvestment Plan (in shares) Note To Financial Statement Details Textual srt_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased Share Repurchase Program, Authorized, Number of Shares (in shares) Note 5 - Fair Value Measurements Compensation and benefits Accrued payment related to management contract Carrying value as of the balance sheet date of obligations incurred through that date and payable for management contractual rights. us-gaap_LeaseExpirationDate1 Lease Expiration Date us-gaap_DebtInstrumentMaturityDate Debt Instrument, Maturity Date Note 6 - Leases Investment Advice [Member] Income tax expense Fair Value Measurement Inputs and Valuation Techniques [Table] us-gaap_DebtInstrumentInterestRateStatedPercentage Debt Instrument, Interest Rate, Stated Percentage ecd_NonRule10b51ArrTrmntdFlag Non-Rule 10b5-1 Arrangement Terminated [Flag] Note 7 - Accrued Liabilities and Accounts Payable ecd_NonRule10b51ArrAdoptedFlag Non-Rule 10b5-1 Arrangement Adopted [Flag] Note 11 - Equity Trading Arrangements, by Individual [Table] Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Table Text Block] Note 12 - Earnings per Share and Dividends per Share Depreciation Material Terms of Trading Arrangement [Text Block] Note 5 - Fair Value Measurements - Assets Categorized on Basis of Various Levels (Details) Employee and director restricted stock vested (in shares) Note 6 - Leases - Schedule of Supplemental Lease Information (Details) Note 6 - Leases - Schedule of Future Maturities of Operating Lease Liabilities (Details) Shares issued for auto-investments pursuant to the 2024 Dividend Reinvestment and Stock Purchase Plan Value of stock issued during the period for auto-investment from a dividend reinvestment plan (DRIP). Note 7 - Accrued Liabilities and Accounts Payable - Schedule of Accrued Liabilities and Accounts Payable (Details) Note 11 - Equity - Schedule of RSU Activity (Details) Shares issued for auto-investments pursuant to the 2024 Dividend Reinvestment and Stock Purchase Plan (in shares) Number of shares issued during the period for auto-investments from a dividend reinvestment plan (DRIP). Note 12 - Earnings per Share and Dividends per Share - Schedule of Weighted Average Number Shares (Details) us-gaap_StockRepurchasedAndRetiredDuringPeriodShares Repurchase of vested employee restricted stock for tax withholding (in shares) Notes To Financial Statements Notes To Financial Statements [Abstract] Share Repurchase Program [Axis] Schedule of Long-Term Debt Instruments [Table] Share Repurchase Program [Domain] Debt Instrument [Axis] Common Stock Including Additional Paid in Capital [Member] us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities Accrued liabilities and accounts payable Cash flows from operating activities Cash flows from investing activities us-gaap_NetCashProvidedByUsedInOperatingActivities Net cash provided by operating activities Basis of Presentation and Significant Accounting Policies [Text Block] Cash flows from financing activities us-gaap_NetCashProvidedByUsedInInvestingActivities Net cash used in investing activities us-gaap_NetCashProvidedByUsedInFinancingActivities Net cash used in financing activities hnna_NumberOfInvestmentFunds Number of Investment Funds Represents the number of investment funds. hnna_NumberOfFunds Number of Funds Represents the number of funds. us-gaap_EffectiveIncomeTaxRateContinuingOperations Effective Income Tax Rate Reconciliation, Percent Assets, fair value Dividend Reinvestment and Stock Purchase Plan (DRSPP) [Member] Information pertaining to the Dividend Reinvestment and Stock Purchase Plan (the “DRSPP”). The Omnibus Plan [Member] Information pertaining to the Omnibus Plan. Stock Buyback Program [Member] Information pertaining to the Stock Buyback Program. The 2026 Notes [Member] Information pertaining to the 2026 Notes. Other Long-term Operating Leases [Member] Information pertaining to other long-term operating leases. Office in Novato, California [Member] Information pertaining to leased office space in Novato, California. us-gaap_DividendsCommonStockCash Dividends paid Accounting Policies [Abstract] us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable Income taxes payable Accounting Standards Update and Change in Accounting Principle [Text Block] Cash dividends declared per share (in dollars per share) us-gaap_IncreaseDecreaseInAccruedInterestReceivableNet Interest income receivable Income Statement [Abstract] Cash and Cash Equivalents [Member] us-gaap_SharesOutstanding Balance (in shares) Balance (in shares) us-gaap_NumberOfOperatingSegments Number of Operating Segments us-gaap_NumberOfReportableSegments Number of Reportable Segments Deferred income taxes Dividends [Axis] Segment Reporting [Text Block] Dividends [Domain] hnna_NumberOfPurchasesOfAssets Number of Purchases of Assets Represents number of purchases of assets. us-gaap_ContractualObligation Contractual Obligation Management Contracts Purchased [Text Block] The entire disclosure for management contracts purchased. Award Type [Axis] Net income Net income Adjustments to reconcile net income to net cash provided by operating activities hnna_NumberOfOpenEndMutualFunds Number of Open End Mutual Funds Represents number of open end mutual funds. Investment Advisory Agreements [Text Block] The entire disclosure for investment advisory agreement. Plan Name [Axis] us-gaap_DividendsPayableDateOfRecordDayMonthAndYear Dividends Payable, Date of Record us-gaap_Liabilities Total liabilities hnna_NoticePeriodForTerminationOfAgreement Notice Period for Termination of Agreement (Day) Duration of notice period to terminate agreement. Plan Name [Domain] hnna_ManagementContractsPurchasedImpairment Management Contracts Purchased, Impairment Amount of impairment of management contracts purchased. Amortization of note issuance costs Change in right-of-use asset and operating lease liability Amount of expense (income) related to changes in right of use assets and operating lease liability. us-gaap_LiabilitiesAndStockholdersEquity Total liabilities and stockholders' equity Marketable Securities [Member] Represents marketable securities. Mutual Fund Investment [Member] Represents mutual fund investment. Exchange-traded Fund [Member] Represents exchange-traded funds. Segment Reporting [Table] us-gaap_IncreaseDecreaseInPrepaidExpense Prepaid expenses Open-end Mutual Funds [Member] Represents open-end mutual funds. us-gaap_OtherCommitment Other Commitment Condensed Balance Sheet Statement [Table] us-gaap_ShareBasedCompensation Stock-based compensation Lessee, Lease, Description [Table] Income Tax Disclosure [Text Block] Lease Contractual Term [Axis] Lease Contractual Term [Domain] Change in operating assets and liabilities Accounting Standards Update and Change in Accounting Principle [Table] Proceeds from shares issued pursuant to the 2024 Dividend Reinvestment and Stock Purchase Plan us-gaap_CommonStockDividendsPerShareCashPaid Common Stock, Dividends, Per Share, Cash Paid (in dollars per share) Other accounts receivable us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations Cash and cash equivalents at the beginning of the period Cash and cash equivalents at the end of the period Share-Based Payment Arrangement, Tranche One [Member] Statement [Table] Fair Value Hierarchy and NAV [Domain] Prepaid expenses Vesting [Axis] Statement of Financial Position [Abstract] Vesting [Domain] us-gaap_IncreaseDecreaseInAccruedInvestmentIncomeReceivable Investment fee income receivable Cash paid for income taxes us-gaap_RepaymentsOfShortTermDebt Principal payments on short-term debt us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber Non-vested balance at beginning of period (in shares) Non-vested balance at end of period (in shares) us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue Non-vested balance, Weighted Average Grant Date Fair Value (in dollars per share) Non-vested balance, Weighted Average Grant Date Fair Value (in dollars per share) Granted (in shares) Granted, Weighted Average Grant Date Fair Value (in dollars per share) us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod Forfeited (in shares) Product and Service [Domain] Sub-advisory fees Product and Service [Axis] hnna_SharesRepurchasedDuringPeriodShares Shares Repurchased During Period, Shares (in shares) The number of shares repurchased during period. hnna_ShareRepurchaseProgramRemainingSharesAuthorizedNumberOfShares Share Repurchase Program, Remaining Shares Authorized, Number of Shares (in shares) Number of shares remaining authorized to be purchased under share repurchase plan. Includes, but is not limited to, repurchase of stock and unit of ownership. Fund distribution and other Mutual fund platform fees. us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue Vested, Weighted Average Grant Date Fair Value (in dollars per share) Unrecognized compensation expense related to RSUs us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod Vested (in shares) Share-Based Payment Arrangement, Option, Exercise Price Range [Table] Other assets us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue Total undiscounted cash flows us-gaap_IncreaseDecreaseInAccountsAndOtherReceivables Other accounts receivable Weighted average discount rate Document Type Operating expenses Asset Class [Axis] Document Information [Line Items] Document Quarterly Report us-gaap_IncreaseDecreaseInOtherNoncurrentAssets Other assets us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths Fiscal year 2027 us-gaap_LesseeOperatingLeaseRenewalTerm Lessee, Operating Lease, Renewal Term (Year) Weighted average remaining lease term (Year) Document Information [Table] us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized (in shares) us-gaap_ProceedsFromIssuanceOfDebt Proceeds from Issuance of Debt us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear Remainder of fiscal year 2026 Entity Interactive Data Current Lessee, Operating Lease, Liability, to be Paid, Maturity [Table Text Block] Document Transition Report Commitments and Contingencies Disclosure [Text Block] Diluted (in shares) Weighted average common stock outstanding, diluted (in shares) Statement [Line Items] us-gaap_OperatingExpenses Total operating expenses Fair Value Hierarchy and NAV [Axis] Common Stock, Issued (in shares) Earnings per share Common Stock, Outstanding (in shares) Award Type [Domain] Common Stock, Authorized (in shares) us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements Dilutive impact of RSUs (in shares) Basic (in shares) Weighted average common stock outstanding, basic (in shares) Schedule of Accounts Payable and Accrued Liabilities [Table Text Block] Basic (in dollars per share) Dividend reinvestment issued in shares us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Rights, Percentage Earnings Per Share, Diluted, by Common Class, Including Two-Class Method [Table] Common stock, no par value, 22,500,000 shares authorized; 7,904,334 shares issued and outstanding as of June 30, 2026, and 7,889,941 as of September 30, 2025 Effective Income Tax Rate Reconciliation [Table] Notes payable, net of issuance costs Schedule of Weighted Average Number of Shares [Table Text Block] Accrued liabilities and accounts payable Total accrued liabilities and accounts payable us-gaap_PolicyTextBlockAbstract Accounting Policies us-gaap_DisclosureTextBlockAbstract Notes to Financial Statements us-gaap_TableTextBlock Notes Tables Accrued bonus liabilities Document Fiscal Period Focus Document Fiscal Year Focus Schedule of Operating Lease Right of Use Assets Lease Liabilities and Other Supplemental Information [Table Text Block] Tabular disclosure for lessee's operating leases. Amendment Flag Management contracts Common Stock [Member] us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffectDisposalGroupIncludingDiscontinuedOperations Net (decrease) increase in cash and cash equivalents Accrued sub-advisor fees Subsequent Events [Text Block] Other accrued expenses Document Period End Date Legal Entity [Axis] Two Thousand Twenty Four Dividend Reinvestment and Stock Purchase Plan [Member] the stock repurchase program for 2024. us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount Present value discount Entity File Number Long-term operating lease liability Entity Tax Identification Number Total operating lease liabilities Operating lease liability Entity [Domain] Entity Central Index Key Entity Registrant Name Entity Current Reporting Status Entity Incorporation, State or Country Code Current Fiscal Year End Date Entity Filer Category Entity Shell Company Entity Emerging Growth Company Entity Small Business us-gaap_OperatingIncomeLoss Net operating income Interest expense Revenue Entity Address, State or Province Statement of Stockholders' Equity [Abstract] Entity Address, City or Town Retained earnings Entity Address, Address Line One Statement of Cash Flows [Abstract] City Area Code Local Phone Number Entity Address, Postal Zip Code Stockholders' equity Title of 12(b) Security Equity Components [Axis] Security Exchange Name Trading Symbol Capitalized Contract Cost [Table] us-gaap_InvestmentCompanyContractualFeeWaived Investment Company, Contractual Fee Waived Class of Stock [Axis] Equity Component [Domain] Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 3 [Member] Equity [Text Block] Fair Value, Inputs, Level 1 [Member] Entity Common Stock, Shares Outstanding Retained Earnings [Member] Earnings Per Share [Text Block] Property and equipment, net of accumulated depreciation of $1,677 and $1,643, respectively Subsequent Event [Table] Income taxes payable Weighted average shares outstanding Stock-based compensation Schedule of Nonvested Restricted Stock Units Activity [Table Text Block] us-gaap_Assets Total assets Net deferred income tax liability Cash and cash equivalents Accounts Payable and Accrued Liabilities Disclosure [Text Block] Interest income receivable Fair Value Disclosures [Text Block] Supplemental disclosures of cash flow information Current liabilities us-gaap_CommonStockCapitalSharesReservedForFutureIssuance Common Stock, Capital Shares Reserved for Future Issuance (in shares) us-gaap_LiabilitiesCurrent Total current liabilities Diluted (in dollars per share) Investment Holdings [Table] Expense related to previously capitalized management contract costs Previously Capitalized Management Contract Costs Amount of expense realted to previously capitalized management contract costs. Asset Class [Domain] Investments in marketable securities, at fair value us-gaap_MarketableSecuritiesUnrealizedGainLoss Unrealized gain on marketable securities us-gaap_PaymentsToAcquireIntangibleAssets Payments related to management contracts Investment fee income receivable us-gaap_InvestmentIncomeInterest Interest income Cash paid for interest Other Commitments [Table] Accumulated depreciation Common Stock, No Par Value (in dollars per share) General and administrative us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest Income before income tax expense Debt Disclosure [Text Block] us-gaap_StockholdersEquity Total stockholders' equity Balance Balance us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue Forfeited, Weighted Average Grant Date Fair Value (in dollars per share) O 2026 Q3 Dividends [Member] Represents O 2026 Q3 Dividends. Weighted average remaining years to expense for RSUs (Year) Employee and director restricted stock vested us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1 Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year) us-gaap_PaymentsOfDividends Dividend payments us-gaap_PaymentsToAcquirePropertyPlantAndEquipment Purchases of property and equipment Lessee, Operating Leases [Text Block] Shares issued for dividend reinvestment pursuant to the 2024 Dividend Reinvestment and Stock Purchase Plan Shareholder Service [Member] us-gaap_StockRepurchasedAndRetiredDuringPeriodValue Repurchase of vested employee restricted stock for tax withholding us-gaap_DebtInstrumentFaceAmount Debt Instrument, Face Amount Current assets Operating lease right-of-use asset Operating Lease, Right-of-Use Asset Money Market Funds [Member] us-gaap_AssetsCurrent Total current assets ecd_Rule10b51ArrTrmntdFlag Rule 10b5-1 Arrangement Terminated [Flag] us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax Revenue ecd_Rule10b51ArrAdoptedFlag Rule 10b5-1 Arrangement Adopted [Flag] Commitments and contingencies (Note 10) Restricted Stock Units (RSUs) [Member]