Document And Entity Information Note To Financial Statement Details Textual us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths 2025 Significant Accounting Policies us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo 2026 Note 3 - Fair Value Measurement Note 4 - Property and Equipment, Net Note 5 - Operating Lease Right-of-use Asset, Net Note 6 - Accrued Expenses and Other Current Liabilities Note 7 - Stockholders' Equity Note 8 - Share-based Compensation Note 9 - Net Loss Per Share Note 3 - Fair Value Measurement - Fair Value of Assets Measured on a Recurring Basis (Details) Income Tax Disclosure [Text Block] Note 4 - Property and Equipment, Net - Summary of Property and Equipment, Net (Details) Note 5 - Operating Lease Right-of-use Asset, Net - Future Minimum Lease Payments Under Operating Lease (Details) Other assets us-gaap_ShareBasedCompensation Share-based compensation Lessee, Operating Lease, Liability, to be Paid, Maturity [Table Text Block] Note 6 - Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Current Liabilities (Details) us-gaap_LiabilitiesCurrent Total current liabilities us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear Remainder of 2024 Note 7 - Stockholders' Equity - Warrants (Details) Note 8 - Share-based Compensation - Share-based Compensation Expense (Details) Note 8 - Share-based Compensation - Stock Option Activity (Details) Note 9 - Net Loss Per Share - Anti-dilutive Securities (Details) Payable to related party Other Liabilities, Current Notes To Financial Statements Notes To Financial Statements [Abstract] Share-Based Payment Arrangement, Option, Activity [Table Text Block] us-gaap_Depreciation Depreciation us-gaap_StockholdersEquityNoteStockSplitConversionRatio1 Stockholders' Equity Note, Stock Split, Conversion Ratio Depreciation Collaboration Agreement [Member] Represents the information pertaining to the collaboration agreement. us-gaap_AssetsCurrent Total current assets Exercisable, weighted average exercise price (in dollars per share) us-gaap_CashAndCashEquivalentsFairValueDisclosure Total cash and cash equivalents Exercisable, weighted average remaining contractual term (Year) Exercisable, aggregate intrinsic value Equity [Text Block] Exercisable, number of shares (in shares) bcda_MaximumDiscountOnLegalService Maximum Discount on Legal Service Maximum discount on legal service. Balance, weighted average remaining contractual term (Year) Balance, aggregate intrinsic value Common stock, $0.001 par value, 50,000,000 and 100,000,000 shares authorized, 2,123,876 and 1,577,769 shares issued and outstanding as of June 30, 2024 and December 31, 2023, respectively Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Measurement Frequency [Axis] Measurement Frequency [Domain] us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice Balance, weighted average exercise price (in dollars per share) Balance, weighted average exercise price (in dollars per share) Fair Value, Recurring [Member] Common Stock, Shares Authorized (in shares) Common Stock, Shares Authorized (in shares) Common Stock, Shares, Issued (in shares) Stock options expired (in dollars per share) us-gaap_CommonStockParOrStatedValuePerShare Common Stock, Par or Stated Value Per Share (in dollars per share) Stock options granted, weighted average exercise price (in dollars per share) Accrued expenses us-gaap_OperatingLeasePayments Operating Lease, Payments Lessee, Operating Leases [Text Block] Accounts payable Product and Service [Axis] us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber Balance, number of shares (in shares) Balance, number of shares (in shares) Product and Service [Domain] us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod Stock options expired (in shares) Preferred stock, $0.001 par value, 25,000,000 shares authorized and no shares issued and outstanding as of June 30, 2024 and December 31, 2023 Preferred Stock, Shares Issued (in shares) us-gaap_PolicyTextBlockAbstract Accounting Policies Accrued salaries and employee benefits Carrying value as of the balance sheet date of the obligations incurred through that date and payable for employees' services provided and employee benefits (due within one year or within the normal operating cycle if longer). Property, Plant and Equipment Disclosure [Text Block] Property, Plant and Equipment [Table Text Block] us-gaap_PreferredStockSharesAuthorized Preferred Stock, Shares Authorized (in shares) Unpaid issuance costs of common stock us-gaap_PreferredStockParOrStatedValuePerShare Preferred Stock, Par or Stated Value Per Share (in dollars per share) Total revenue ATM [Member] Represents ATM agreement. us-gaap_TypeOfRevenueExtensibleList Revenue, Product and Service [Extensible Enumeration] Fair Value, Inputs, Level 3 [Member] us-gaap_PaymentsToAcquirePropertyPlantAndEquipment Purchase of property and equipment Fair Value Hierarchy and NAV [Domain] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value Hierarchy and NAV [Axis] Employees, Non-employees and Non-employee Directors [Member] Represents Employees, Non-employees and Non-employee Directors us-gaap_Assets Total assets Deferred revenue us-gaap_IncreaseDecreaseInDeferredRevenue us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions Share-Based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions Share-Based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount Operating activities: us-gaap_OperatingLeaseExpense Operating Lease, Expense us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1 Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Statement [Line Items] Accounts Receivable, Allowance for Credit Loss, Current Accounts receivable, net of allowance for doubtful accounts of $0 and $34 as of June 30, 2024 and December 31, 2023, respectively Furniture and Fixtures [Member] Additional paid-in capital Share-Based Payment Arrangement [Text Block] Leasehold Improvements [Member] Total other income, net Long-Lived Tangible Asset [Axis] Long-Lived Tangible Asset [Domain] Business Description and Basis of Presentation [Text Block] Award Type [Domain] Warrants for common stock sold, weighted average exercise price (in dollars per share) Weighted average exercise price per share or per unit of warrants or rights issued during the period. Fair Value Disclosures [Text Block] Net loss Net loss Award Type [Axis] us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Restricted Stock Units (RSUs) [Member] us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect Net change in cash and cash equivalents us-gaap_Liabilities Total liabilities us-gaap_NetCashProvidedByUsedInFinancingActivities Net cash provided by financing activities Commitments and Contingencies Sale of Stock [Axis] Sale of Stock [Domain] us-gaap_OperatingIncomeLoss Operating loss us-gaap_NetCashProvidedByUsedInOperatingActivities Net cash used in operating activities Share-Based Payment Arrangement, Option [Member] Prepaid expenses and other current assets us-gaap_NetCashProvidedByUsedInInvestingActivities Net cash used in investing activities Warrant [Member] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Accrued expenses and other current liabilities Total Amount of accrued liabilities and liabilities classified as other, due within one year or the normal operating cycle, if longer. Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block] us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment Less accumulated depreciation Property and equipment, net Property and equipment, net Management [Member] Contingencies Disclosure [Text Block] Schedule of Accrued Liabilities and Other Current Liabilities [Table Text Block] Tabular disclosure of the components of accrued liabilities and other current liabilities. Accrued Liabilities and Other Current Liabilities Disclosure [Text Block] The entire disclosure for accrued liabilities and other current liabilities at the end of the reporting period. Grant liability Amount of obligations incurred for grants, payable within one year or the normal operating cycle, if longer. Property and equipment, gross us-gaap_PaymentsOfStockIssuanceCosts Issuance costs of sale of common stock Payments of Stock Issuance Costs Concentration Risk, Credit Risk, Policy [Policy Text Block] Customer deposits The amount of customer deposit liabilities classified as current. us-gaap_CostsAndExpenses Total costs and expenses us-gaap_ProceedsFromIssuanceOrSaleOfEquity Proceeds from Issuance of Common Stock Investing activities: Retained Earnings [Member] Earnings Per Share [Text Block] Title and Position [Domain] Proceeds from sales of common stock Proceeds from Issuance of Common Stock Funding Agreement [Member] Represents information regarding the Funding Agreement, for the purpose of funding the Company's currently pending legal proceedings and any and all claims, actions and/or proceedings relating to or arising from the case captioned Boston Scientific Corp., et al., v. BioCardia Inc., Case No. 3:19-05645-VC, U.S.D.C., N. D. Cal (the "Litigation"). Title and Position [Axis] BSLF, L.L.C. [Member] Represents information regarding BSLF, L.L.C., an entity owned and controlled by Andrew Blank, a member of BioCardia's board of directors. Additional Paid-in Capital [Member] Common Stock [Member] Related Party Transactions Disclosure [Text Block] us-gaap_IncomeTaxExpenseBenefit Income Tax Expense (Benefit) bcda_SaleOfStockAvailableValue Sale of Stock, Available Value Represents value of common stock available to sale under purchase agreement at period end. Equity Components [Axis] Equity Component [Domain] Accounts payable us-gaap_IncreaseDecreaseInAccountsPayable us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1 Class of Warrant or Right, Exercise Price of Warrants or Rights Balance, weighted average exercise price (in dollars per share) Balance as, weighted average exercise price (in dollars per share) us-gaap_ClassOfWarrantOrRightOutstanding Balance , number of common stock warrants (in shares) Balance , number of common stock warrants (in shares) us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights Class of Warrant or Right, Number of Securities Called by Warrants or Rights Sales Agreement with Cantor Fitzgerald Co (Cantor) [Member] Represents the Sale Agreement with Cantor Fitzgerald & Co. Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value us-gaap_AllocatedShareBasedCompensationExpense Total share-based compensation us-gaap_LegalFees Legal Fees Document Quarterly Report Entity Incorporation, State or Country Code Amendment Flag Accounting Policies [Abstract] Significant Accounting Policies [Text Block] Document Transition Report dei_CityAreaCode City Area Code Basis of Accounting, Policy [Policy Text Block] New Accounting Pronouncements, Policy [Policy Text Block] Selling, General and Administrative Expenses [Member] dei_EntityInteractiveDataCurrent Entity Interactive Data Current Related Party [Member] us-gaap_IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities Accrued expenses and other current liabilities us-gaap_StockIssuedDuringPeriodSharesReverseStockSplits Reverse stock split fractional share true up (in shares) us-gaap_SharesOutstanding Balance (in shares) Balance (in shares) Going Concern and Liquidity [Policy Text Block] Disclosure of accounting policy for reporting when there is, or is not, a substantial doubt about an entity's ability to continue as a going concern for a reasonable period of time (generally a year from the balance sheet date). Disclose: (a) pertinent conditions and events giving rise to the assessment of substantial doubt about the entity's ability to continue as a going concern for a reasonable period of time, (b) the possible effects of such conditions and events, (c) management's evaluation of the significance of those conditions and events and any mitigating factors, (d) possible discontinuance of operations, (e) management's plans (including relevant prospective financial information), and (f) information about the recoverability or classification of recorded asset amounts or the amounts or classification of liabilities. If management's plans alleviate the substantial doubt about the entity's ability to continue as a going concern, disclosure of the principal conditions and events that initially raised the substantial doubt about the entity's ability to continue as a going concern would be expected to be considered. Disclose whether operations for the current or prior years generated sufficient cash to cover current obligations, whether waivers were obtained from creditors relating to the company's default under the provisions of debt agreements and possible effects of such conditions and events, such as: whether there is a possible need to obtain additional financing (debt or equity) or to liquidate certain holdings to offset future cash flow deficiencies. Disclose appropriate parent company information when parent is dependent upon remittances from subsidiaries to satisfy its obligations. Security Exchange Name Common Stock, Shares, Outstanding (in shares) Preferred Stock, Shares Outstanding (in shares) Title of 12(b) Security Current Fiscal Year End Date us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets Prepaid expenses and other current assets Computer Equipment and Software [Member] Related to computer equipment and software. us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent Operating Lease, Weighted Average Discount Rate, Percent Research and Development Expense [Member] Document Fiscal Period Focus Document Fiscal Year Focus Consolidation, Policy [Policy Text Block] Laboratory and Manufacturing Equipment [Member] Related to laboratory and manufacturing equipment. bcda_SaleOfStockAggregateValueMaximum Sale of Stock, Aggregate Value, Maximum Represents maximum aggregate value of common stock available to sale under purchase agreement. dei_DocumentPeriodEndDate Document Period End Date Statement of Income Location, Balance [Axis] us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1 Operating Lease, Weighted Average Remaining Lease Term Warrants for common stock sold , number of common stock warrants (in shares) The number of warrants or rights issued during period. Statement of Income Location, Balance [Domain] dei_EntityFileNumber Entity File Number Nonmonetary Transaction Type [Domain] Entity Emerging Growth Company dei_DocumentType Document Type February 2024 Financing [Member] February 2024 Financing Entity Small Business dei_EntityShellCompany Entity Shell Company Nonmonetary Transaction Type [Axis] bcda_AccruedSalesCommissionCurrentPercentage Accrued Sales Commission, Current, Percentage Represents the current accrued sales commission's percentage. Document Information [Line Items] Document Information [Table] Entity Filer Category dei_EntityCurrentReportingStatus Entity Current Reporting Status bcda_LitigationServiceExpense Litigation Service, Expense Represents litigation service, expense. Schedule of Share-based Compensation, Expense [Table Text Block] Tabular disclosure of the components of the allocated share-based compensation expense. Antidilutive securities (in shares) us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue Share-based compensation us-gaap_IncreaseDecreaseInAccountsReceivable Accounts receivable Entity Tax Identification Number Entity Central Index Key dei_EntityRegistrantName Entity Registrant Name us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition Restricted stock units issued to settle management bonus obligations Entity [Domain] Legal Entity [Axis] Statement [Table] dei_EntityAddressAddressLine1 Entity Address, Address Line One Statement of Financial Position [Abstract] us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs Weighted-average shares used in computing net loss per share, basic and diluted (in shares) ecd_NonRule10b51ArrTrmntdFlag Non-Rule 10b5-1 Arrangement Terminated [Flag] dei_EntityAddressCityOrTown Entity Address, City or Town ecd_Rule10b51ArrTrmntdFlag Rule 10b5-1 Arrangement Terminated [Flag] ecd_Rule10b51ArrAdoptedFlag Rule 10b5-1 Arrangement Adopted [Flag] dei_EntityAddressPostalZipCode Entity Address, Postal Zip Code Supplemental disclosure of noncash investing and financing activities: Net loss per share, basic and diluted (in dollars per share) dei_EntityAddressStateOrProvince Entity Address, State or Province ecd_NonRule10b51ArrAdoptedFlag Non-Rule 10b5-1 Arrangement Adopted [Flag] Material Terms of Trading Arrangement [Text Block] Statement of Cash Flows [Abstract] dei_EntityCommonStockSharesOutstanding Entity Common Stock, Shares Outstanding (in shares) Statement of Stockholders' Equity [Abstract] Income Statement [Abstract] Change to Significant Accounting Policies [Policy Text Block] Disclosure of accounting policy for change to significant accounting policies. Trading Symbol bcda_CashPercentageHeldInOneFinancialInstitution Cash, Percentage Held in One Financial Institution Percentage of cash held in one financial institution. dei_LocalPhoneNumber Local Phone Number Exercise of common stock options (in shares) us-gaap_TableTextBlock Notes Tables Stock Issued During Period, Shares, Restricted Stock Award, Gross (in shares) Exercise of common stock options Issuance of restricted stock units in lieu of cash bonus obligations The cash inflow from the issuance of restricted stock units in lieu of cash bonus. Related and Nonrelated Parties [Axis] Related and Nonrelated Parties [Domain] Selling, general and administrative Allowance for doubtful accounts Operating lease liability The amount of increase (decrease) in noncurrent operating lease liability. Financing activities: Stock options granted, number of shares (in shares) Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Sale of common stock, net of issuance costs (in shares) Stock Issued During Period, Shares, New Issues (in shares) us-gaap_LiabilitiesAndStockholdersEquity Total liabilities and stockholders’ deficit us-gaap_CashUninsuredAmount Cash, Uninsured Amount Sale of common stock, net of issuance costs Related Party Transaction [Axis] Accrued clinical trial costs Amount of obligations incurred for clinical trial costs, payable within one year or the normal operating cycle, if longer. Related Party Transaction [Domain] Savings Account [Member] Represents Savings Account Accumulated deficit Retained Earnings (Accumulated Deficit) Research and development Demand Deposits [Member] Money Market Funds [Member] Cash and Cash Equivalents [Axis] Cash and Cash Equivalents [Domain] Changes in operating assets and liabilities: Balance Total stockholders’ deficit Balance Balance Reduction in the carrying amount of right-of-use assets us-gaap_DisclosureTextBlockAbstract Notes to Financial Statements Operating lease liability - noncurrent Sales Agreement With H.C. Wainwright & Co., LLC [Member] The sales agreement with H.C. Wainwright & Co., LLC. Class of Stock [Axis] Total operating lease liabilities Operating lease liability - current Operating lease right-of-use asset, net us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue Total undiscounted lease payments Less imputed interest us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree 2027 Reverse Stock Split [Member] Represents reverse stock split.