Document And Entity Information Statistical Measurement [Axis] Note To Financial Statement Details Textual us-gaap_DividendsPayableDateDeclaredDayMonthAndYear Dividends Payable, Date Declared Significant Accounting Policies Investment, Policy [Policy Text Block] Schedule of Investments (Unaudited) ecd_NonRule10b51ArrTrmntdFlag Non-Rule 10b5-1 Arrangement Terminated [Flag] Note 2 - Significant Accounting Policies Options written us-gaap_GainLossOnSaleOfDerivatives ecd_NonRule10b51ArrAdoptedFlag Non-Rule 10b5-1 Arrangement Adopted [Flag] Note 8 - Financial Highlights Trading Arrangements, by Individual [Table] Note 9 - Investing in Written Options Material Terms of Trading Arrangement [Text Block] Note 10 - Investment Valuation Related and Nonrelated Parties [Axis] Schedule of Investments (Unaudited) - Investments (Details) Realized gains Amount, before tax, of realized gain on investment and derivative, classified as operating. Investment includes, but is not limited to, debt and equity securities, security sold short, real estate, and commodity. Schedule of Investments (Unaudited) - Investments (Details) (Parentheticals) Schedule of Investments (Unaudited) - Affiliated Investments (Details) Schedule of Investments (Unaudited) - Derivative Financial Instruments Outstanding as of Period End (Details) bita_SponsorFeesWaived Sponsor Fees Waived Sponsor’s fee waived Amount of sponsor fees waived during period. Note 2 - Significant Accounting Policies - Activity in Bitcoin (Details) Note 8 - Financial Highlights - Financial Highlights (Details) Statistical Measurement [Domain] Note 9 - Investing in Written Options - Fair Value, by Risk Exposure Category, on the Statement of Assets and Liabilities (Details) Maximum [Member] Receivable for capital shares sold Amount of receivable for capital shares sold. Note 9 - Investing in Written Options - Effect of the Written Options, by Risk Exposure Category, on the Statement of Operations (Details) Net asset value per Share (Note 2E) (in dollars per share) bita_ValueOfStockClassifiedAsTemporaryEquitySurrenderedDuringReportingPeriod Distributions for Shares redeemed Represents the value of stock classified as temporary equity surrendered during the reporting period. Note 10 - Investment Valuation - Valuation of the Trust's Investments by the Fair Value Hierarchy (Details) bita_IncreaseDecreaseInNetAssets Increase in net assets Increase (decrease) in net assets. Notes To Financial Statements Capital Share Transactions: Notes To Financial Statements [Abstract] Shares issued and redeemed us-gaap_InvestmentOwnedPercentOfNetAssets Investment, percentage of net assets Operations: Schedule of Investments [Table] Realized losses Amount, before tax, of realized loss on investment and derivative, classified as operating. Investment includes, but is not limited to, debt and equity securities, security sold short, real estate, and commodity. Shares, par value (in dollars per share) Payable for investments purchased Options written us-gaap_UnrealizedGainLossOnDerivatives Cash Flows from Operating Activities Total Investments Net of Options Written Fair value of investment in security owned, net of derivative. Total Investments Net of Options Written, percentage of net assets Percentage of investment owned, net derivative, to net assets. us-gaap_NetCashProvidedByUsedInOperatingActivities Net cash used in operating activities Net assets, percentage of net asset value The percentage of net assets of net assets. Cash Provided by Financing Activities Business Description and Basis of Presentation [Text Block] us-gaap_SharesIssuedPricePerShare Shares Issued, Price Per Share (in dollars per share) Shares redeemed (in shares) Number of shares of stock classified as temporary equity surrendered during the reporting period. bita_PaymentsToAcquireInvestmentInCryptoAssets Purchases of bitcoin Amount of cash outflow for investments in crypto assets. us-gaap_NetCashProvidedByUsedInFinancingActivities Net cash provided by financing activities Exchange Traded Options Three [Member] Contracts conveying rights, but not obligations, to buy or sell a specific or standard commodity, or financial or equity instrument, at a specified price during a specified period (an American option) or at a specified date (a European option), which are traded on a stock exchange. us-gaap_ManagementAndServiceFeesBaseRate Management and Service Fees, Base Rate Exchange Traded Options Four [Member] Contracts conveying rights, but not obligations, to buy or sell a specific or standard commodity, or financial or equity instrument, at a specified price during a specified period (an American option) or at a specified date (a European option), which are traded on a stock exchange. Exchange Traded Options One [Member] Contracts conveying rights, but not obligations, to buy or sell a specific or standard commodity, or financial or equity instrument, at a specified price during a specified period (an American option) or at a specified date (a European option), which are traded on a stock exchange. Exchange Traded Options Two [Member] Contracts conveying rights, but not obligations, to buy or sell a specific or standard commodity, or financial or equity instrument, at a specified price during a specified period (an American option) or at a specified date (a European option), which are traded on a stock exchange. us-gaap_LiabilitiesFairValueDisclosure Total Liabilities Capital Gain Distributions from Underlying Funds Amount of capital gain distributions from underlying funds. Counterparty Name [Axis] Total Investments Net of Options Written, cost Cost of the investment, net of derivative. Bitcoin [Member] Represents Bitcoin. us-gaap_AssetsFairValueDisclosure Total Assets Securities Transactions Income and Expense Recognition [Policy Text Block] Describes the entity's accounting policy for securities transactions and recognition of income and expense. us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease Net increase in Shares issued and outstanding (in shares) Activity in Bitcoin [Table Text Block] Tabular disclosure of the quantity, average cost, fair value and realized gain (loss) related to activity in bitcoin. Offering of the Shares [Policy Text Block] Disclosure of accounting policy for creation and redemption of shares. Net investment loss Distributions [Policy Text Block] Describes the entity's accounting policy regarding distributions to shareholders. bita_SharesPrescribedAggregation Shares Prescribed Aggregation (in shares) Prescribed aggregation at which shares are issued and redeemed. us-gaap_InvestmentCompanyExpenseAfterReductionOfFeeWaiverAndReimbursement Total expenses Calculation of Net Asset Value [Policy Text Block] Disclosure of accounting policy for creation and redemption of shares. BlackRock Financial Management, Inc. [Member] Represents BlackRock Financial Management, Inc. bita_CryptoAssetNumberOfUnitsPurchase Crypto Asset, Number of Units, Purchase Number of restricted and unrestricted crypto asset units purchased during the period. Excludes crypto asset units held for platform user. Indemnification [Text Block] Includes disclosure of indemnification. us-gaap_RealizedAndUnrealizedGainLossInvestmentAndDerivativeOperatingBeforeTax Net realized and unrealized loss bita_AverageNotionalAmountOfDerivativeContracts Average Notional Amount of Derivative Contracts Amount of average notional amount specified by the derivative contracts. bita_LegalFeesPerYear Legal Fees Per Year Maximum per annum in legal fees and expenses the sponsor has agreed to assume. Net realized gain Net realized gain bita_OwnershipPercentage Ownership Percentage Percentage of ownership. Accounting Policies [Abstract] Net change in unrealized appreciation/depreciation Net change in unrealized appreciation/depreciation Trust Expenses [Text Block] The entire disclosure for expenses incurred by the Trust. Bitcoin purchased, quantity Quantity of bitcoin purchased for the creation of shares. Bitcoin purchased, cost Average cost of bitcoin purchased for the creation of shares. us-gaap_PaymentsForPurchaseOfInvestmentOperatingActivity Purchases of investments Income Total investment income Proceeds from sales of investments O 2026 Q2 Dividends [Member] Represents ordinary 2026 Q2 dividend. Investments Before Options Written [Member] Represents investments before written options. Contributions for Shares issued iShares Bitcoin Trust ETF [Member] Represents iShares Bitcoin Trust ETF. Counterparty Name [Domain] Income Statement [Abstract] BlackRock Cash Funds: Treasury, SL Agency Shares [Member] Represents BlackRock Cash Funds: Treasury, SL Agency Shares. Cash Net increase in net assets from capital share transactions Dividends [Axis] Dividends [Domain] us-gaap_CryptoAssetNumberOfUnits Bitcoin, quantity Beginning balance, quantity Ending balance, quantity Net decrease in net assets resulting from operations Net decrease in net assets resulting from operations Adjustments to reconcile net increase (decrease) in net assets resulting from operations to net cash provided by (used in) operating activities: us-gaap_DividendsPayableDateOfRecordDayMonthAndYear Dividends Payable, Date of Record Liabilities Expenses us-gaap_NetInvestmentIncome Net investment loss Subsequent Event [Member] Net realized gain from: Net change in unrealized appreciation/depreciation on: us-gaap_IncreaseDecreaseInAccountsPayableRelatedParties Sponsor’s fee payable Change in operating assets and liabilities: Accounting Standards Update and Change in Accounting Principle [Table] Income Tax, Policy [Policy Text Block] Fair Value, by Balance Sheet Grouping [Table] us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect Net increase in cash us-gaap_DerivativePriceRiskOptionStrikePrice Exercise Price (in USD per Per Share) Related and Nonrelated Parties [Domain] Related Party Transaction [Table] us-gaap_IncreaseDecreaseInPremiumsReceivable Receivable for options premium Related Party Transactions Disclosure [Text Block] Receivable for options premium us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations Cash, beginning of period Cash, end of period Statement [Table] Fair Value Hierarchy and NAV [Domain] us-gaap_DerivativeNetAssetsPercentage Options Written, percentage of net assets Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Table] Investment in bitcoin, at cost Bitcoin, cost Beginning balance, cost Ending balance, cost Statement of Financial Position [Abstract] us-gaap_InvestmentsFairValueDisclosure Investment, fair value us-gaap_DerivativeMaturityDates Expiration Date us-gaap_DividendPayableDateToBePaidDayMonthAndYear Dividends Payable, Date to be Paid Financial Support for Nonconsolidated Legal Entity [Table] Sponsor’s fee payable Equity contracts Options written, at value Options Written Net change in unrealized appreciation/depreciation, fair value Investments in bitcoin Investment in bitcoin, at fair value Bitcoin, fair value Beginning balance, fair value Ending balance, fair value us-gaap_IncreaseDecreaseInDividendsReceivable Receivable for dividends – affiliated Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Table Text Block] Bitcoin purchased, fair value us-gaap_NetAssetValuePerShare Net asset value per Share, beginning of period (in dollars per share) Net asset value per Share, end of period (in dollars per share) us-gaap_SharesIssued Shares, Issued (in shares) Document Type Document Information [Line Items] Document Quarterly Report Document Information [Table] Entity Interactive Data Current Assets Commitments and Contingencies Disclosure [Text Block] Document Transition Report Statement [Line Items] Net Assets Net Assets Net Assets, Beginning of Period Net Assets, End of Period Fair Value Hierarchy and NAV [Axis] Net realized gain (loss) Investments – affiliated Net change in unrealized appreciation/depreciation Derivative Instrument [Axis] Net decrease in net assets per Share (in dollars per share) Proceeds from issuance of Shares us-gaap_PolicyTextBlockAbstract Accounting Policies us-gaap_DisclosureTextBlockAbstract Notes to Financial Statements us-gaap_TableTextBlock Notes Tables Document Fiscal Period Focus Document Fiscal Year Focus Amendment Flag Concentration Risk [Table] Subsequent Events [Text Block] Document Period End Date Investment [Table Text Block] Concentration Risk Disclosure [Text Block] us-gaap_DividendsPayableCurrent Dividends Payable, Current Dividends – affiliated Legal Entity [Axis] Significant Accounting Policies [Text Block] Schedule of Investments in and Advances to Affiliates, Schedule of Investments [Table Text Block] Entity File Number Entity Tax Identification Number 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 Ex Transition Period Entity Filer Category Crypto Asset [Domain] Entity Shell Company Entity Emerging Growth Company us-gaap_DerivativeNotionalAmount Notional Amount Entity Small Business Crypto Asset [Axis] us-gaap_DerivativeNumberOfInstrumentsHeld Number of Contracts Investments [Domain] Exchange Traded Options [Member] Sponsor’s fee Sponsor Fees Derivative Instruments and Hedging Activities Disclosure [Text Block] Investment Income Loss Contingencies [Table] Entity Address, State or Province Statement of Stockholders' Equity [Abstract] Entity Address, City or Town Entity Address, Address Line One Statement of Cash Flows [Abstract] City Area Code Local Phone Number Entity Address, Postal Zip Code Derivative [Table] Title of 12(b) Security Equity Components [Axis] Security Exchange Name Trading Symbol Derivatives, Policy [Policy Text Block] Class of Stock [Axis] Equity Component [Domain] Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Inputs, Level 1 [Member] Entity Common Stock, Shares Outstanding Subsequent Event Type [Domain] Subsequent Event [Table] Subsequent Event Type [Axis] Derivative Instruments, Gain (Loss) [Table Text Block] Derivative Instruments, Gain (Loss) [Table] Basis of Accounting, Policy [Policy Text Block] Derivative Contract [Domain] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Cash and Cash Equivalents, Policy [Policy Text Block] Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Fair Value Disclosures [Text Block] us-gaap_GainLossOnDerivativeInstrumentsNetPretax Change in options written, at value Investments, at fair value — affiliated Investment, fair value Beginning value Ending value Shares Held at period end (in shares) Investment, quantity (in shares) Shares, issued (in shares) Shares issued and outstanding (in shares) Schedule of Investments [Text Block] Investment Company, Financial Highlights [Text Block] Receivable for dividends — affiliated Investment Holdings [Table] Investment Company, Financial Highlights [Table Text Block] Schedule of Derivative Instruments [Table Text Block] Investment Type [Axis] us-gaap_InvestmentCompanyInvestmentIncomeLossFromOperationsPerShare Net decrease in net assets from operations (in dollars per share) Net investment loss (in dollars per share) Net realized and unrealized loss (in dollars per share) Investment Company, Financial Highlights [Table] Investments, at cost — affiliated Investment, cost Investment Holdings, Other than Securities [Table] Total return, at net asset value Liabilities in Excess of Other Assets, percentage of net assets us-gaap_InvestmentCompanyInvestmentIncomeLossRatio Net investment loss Liabilities in Excess of Other Assets Ratio to average net assets: us-gaap_InvestmentCompanyExpenseRatioAfterIncentiveAllocation Total expenses after fees waived(g)(h) Other Commitments [Table] us-gaap_InvestmentCompanyExpenseRatioBeforeIncentiveAllocation Total expenses(g)(h) us-gaap_InvestmentCompanyTotalReturnAfterIncentiveFees Investment Company, Total Return after Incentive Fees Options written, premiums received Options Written, Premiums Received bita_PolicyTable Segment Reporting, Policy [Policy Text Block] Investment, Affiliated Issuer [Member] Investment, Issuer Affiliation [Axis] Investment, Issuer Affiliation [Domain] us-gaap_StockIssuedDuringPeriodValueNewIssues Stock Issued During Period, Value, New Issues Proceeds from sales Nature of Operation, Product Information, Concentration of Risk [Table] Purchases at cost ecd_Rule10b51ArrTrmntdFlag Rule 10b5-1 Arrangement Terminated [Flag] ecd_Rule10b51ArrAdoptedFlag Rule 10b5-1 Arrangement Adopted [Flag] Shares issued (in shares) Stock Issued During Period, Shares, New Issues (in shares) Commitments and contingent liabilities (Note 6)