3.26.1 html 482 363 1 true 121 0 false 4 false false R1.htm 000 - Document - Document And Entity Information Sheet http://clene.com/20260630/role/statement-document-and-entity-information Document And Entity Information Cover 1 false false R2.htm 001 - Statement - Condensed Consolidated Balance Sheets (Current Period Unaudited) Sheet http://clene.com/20260630/role/statement-condensed-consolidated-balance-sheets-current-period-unaudited Condensed Consolidated Balance Sheets (Current Period Unaudited) Statements 2 false false R3.htm 002 - Statement - Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) Sheet http://clene.com/20260630/role/statement-condensed-consolidated-balance-sheets-current-period-unaudited-parentheticals Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) Statements 3 false false R4.htm 003 - Statement - Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) Sheet http://clene.com/20260630/role/statement-condensed-consolidated-statements-of-operations-and-comprehensive-loss-unaudited Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) Statements 4 false false R5.htm 004 - Statement - Condensed Consolidated Statements of Stockholders' Deficit (Unaudited) Sheet http://clene.com/20260630/role/statement-condensed-consolidated-statements-of-stockholders-deficit-unaudited Condensed Consolidated Statements of Stockholders' Deficit (Unaudited) Statements 5 false false R6.htm 005 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited) Sheet http://clene.com/20260630/role/statement-condensed-consolidated-statements-of-cash-flows-unaudited Condensed Consolidated Statements of Cash Flows (Unaudited) Statements 6 false false R7.htm 006 - Disclosure - Note 1 - Nature of the Business Sheet http://clene.com/20260630/role/statement-note-1-nature-of-the-business Note 1 - Nature of the Business Notes 7 false false R8.htm 007 - Disclosure - Note 2 - Summary of Significant Accounting Policies Sheet http://clene.com/20260630/role/statement-note-2-summary-of-significant-accounting-policies Note 2 - Summary of Significant Accounting Policies Notes 8 false false R9.htm 008 - Disclosure - Note 3 - Cash and Cash Equivalents Sheet http://clene.com/20260630/role/statement-note-3-cash-and-cash-equivalents Note 3 - Cash and Cash Equivalents Notes 9 false false R10.htm 009 - Disclosure - Note 4 - Prepaid Expenses and Other Current Assets Sheet http://clene.com/20260630/role/statement-note-4-prepaid-expenses-and-other-current-assets Note 4 - Prepaid Expenses and Other Current Assets Notes 10 false false R11.htm 010 - Disclosure - Note 5 - Property and Equipment, Net Sheet http://clene.com/20260630/role/statement-note-5-property-and-equipment-net Note 5 - Property and Equipment, Net Notes 11 false false R12.htm 011 - Disclosure - Note 6 - Accrued Liabilities Sheet http://clene.com/20260630/role/statement-note-6-accrued-liabilities Note 6 - Accrued Liabilities Notes 12 false false R13.htm 012 - Disclosure - Note 7 - Leases Sheet http://clene.com/20260630/role/statement-note-7-leases Note 7 - Leases Notes 13 false false R14.htm 013 - Disclosure - Note 8 - Notes Payable and Convertible Notes Payable Notes http://clene.com/20260630/role/statement-note-8-notes-payable-and-convertible-notes-payable Note 8 - Notes Payable and Convertible Notes Payable Notes 14 false false R15.htm 014 - Disclosure - Note 9 - Commitments and Contingencies Sheet http://clene.com/20260630/role/statement-note-9-commitments-and-contingencies Note 9 - Commitments and Contingencies Notes 15 false false R16.htm 015 - Disclosure - Note 10 - Income Taxes Sheet http://clene.com/20260630/role/statement-note-10-income-taxes Note 10 - Income Taxes Notes 16 false false R17.htm 016 - Disclosure - Note 11 - Benefit Plans Sheet http://clene.com/20260630/role/statement-note-11-benefit-plans Note 11 - Benefit Plans Notes 17 false false R18.htm 017 - Disclosure - Note 12 - Fair Value Sheet http://clene.com/20260630/role/statement-note-12-fair-value Note 12 - Fair Value Notes 18 false false R19.htm 018 - Disclosure - Note 13 - Capital Stock Sheet http://clene.com/20260630/role/statement-note-13-capital-stock Note 13 - Capital Stock Notes 19 false false R20.htm 019 - Disclosure - Note 14 - Net Loss Per Share Sheet http://clene.com/20260630/role/statement-note-14-net-loss-per-share- Note 14 - Net Loss Per Share Notes 20 false false R21.htm 020 - Disclosure - Note 15 - Related Party Transactions Sheet http://clene.com/20260630/role/statement-note-15-related-party-transactions Note 15 - Related Party Transactions Notes 21 false false R22.htm 021 - Disclosure - Note 16 - Geographic and Segment Information Sheet http://clene.com/20260630/role/statement-note-16-geographic-and-segment-information Note 16 - Geographic and Segment Information Notes 22 false false R23.htm 995445 - Disclosure - Insider Trading Arrangements Sheet http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements Insider Trading Arrangements Notes 23 false false R24.htm 995468 - Disclosure - Significant Accounting Policies (Policies) Sheet http://clene.com/20260630/role/statement-significant-accounting-policies-policies Significant Accounting Policies (Policies) Policies http://clene.com/20260630/role/statement-note-2-summary-of-significant-accounting-policies 24 false false R25.htm 995469 - Disclosure - Note 3 - Cash and Cash Equivalents (Tables) Sheet http://clene.com/20260630/role/statement-note-3-cash-and-cash-equivalents-tables Note 3 - Cash and Cash Equivalents (Tables) Tables http://clene.com/20260630/role/statement-note-3-cash-and-cash-equivalents 25 false false R26.htm 995470 - Disclosure - Note 4 - Prepaid Expenses and Other Current Assets (Tables) Sheet http://clene.com/20260630/role/statement-note-4-prepaid-expenses-and-other-current-assets-tables Note 4 - Prepaid Expenses and Other Current Assets (Tables) Tables http://clene.com/20260630/role/statement-note-4-prepaid-expenses-and-other-current-assets 26 false false R27.htm 995471 - Disclosure - Note 5 - Property and Equipment, Net (Tables) Sheet http://clene.com/20260630/role/statement-note-5-property-and-equipment-net-tables Note 5 - Property and Equipment, Net (Tables) Tables http://clene.com/20260630/role/statement-note-5-property-and-equipment-net 27 false false R28.htm 995472 - Disclosure - Note 6 - Accrued Liabilities (Tables) Sheet http://clene.com/20260630/role/statement-note-6-accrued-liabilities-tables Note 6 - Accrued Liabilities (Tables) Tables http://clene.com/20260630/role/statement-note-6-accrued-liabilities 28 false false R29.htm 995473 - Disclosure - Note 7 - Leases (Tables) Sheet http://clene.com/20260630/role/statement-note-7-leases-tables Note 7 - Leases (Tables) Tables http://clene.com/20260630/role/statement-note-7-leases 29 false false R30.htm 995474 - Disclosure - Note 8 - Notes Payable and Convertible Notes Payable (Tables) Notes http://clene.com/20260630/role/statement-note-8-notes-payable-and-convertible-notes-payable-tables Note 8 - Notes Payable and Convertible Notes Payable (Tables) Tables http://clene.com/20260630/role/statement-note-8-notes-payable-and-convertible-notes-payable 30 false false R31.htm 995475 - Disclosure - Note 10 - Income Taxes (Tables) Sheet http://clene.com/20260630/role/statement-note-10-income-taxes-tables Note 10 - Income Taxes (Tables) Tables http://clene.com/20260630/role/statement-note-10-income-taxes 31 false false R32.htm 995476 - Disclosure - Note 11 - Benefit Plans (Tables) Sheet http://clene.com/20260630/role/statement-note-11-benefit-plans-tables Note 11 - Benefit Plans (Tables) Tables http://clene.com/20260630/role/statement-note-11-benefit-plans 32 false false R33.htm 995477 - Disclosure - Note 12 - Fair Value (Tables) Sheet http://clene.com/20260630/role/statement-note-12-fair-value-tables Note 12 - Fair Value (Tables) Tables http://clene.com/20260630/role/statement-note-12-fair-value 33 false false R34.htm 995478 - Disclosure - Note 13 - Capital Stock (Tables) Sheet http://clene.com/20260630/role/statement-note-13-capital-stock-tables Note 13 - Capital Stock (Tables) Tables http://clene.com/20260630/role/statement-note-13-capital-stock 34 false false R35.htm 995479 - Disclosure - Note 14 - Net Loss Per Share (Tables) Sheet http://clene.com/20260630/role/statement-note-14-net-loss-per-share-tables Note 14 - Net Loss Per Share (Tables) Tables http://clene.com/20260630/role/statement-note-14-net-loss-per-share- 35 false false R36.htm 995480 - Disclosure - Note 15 - Related Party Transactions (Tables) Sheet http://clene.com/20260630/role/statement-note-15-related-party-transactions-tables Note 15 - Related Party Transactions (Tables) Tables http://clene.com/20260630/role/statement-note-15-related-party-transactions 36 false false R37.htm 995481 - Disclosure - Note 16 - Geographic and Segment Information (Tables) Sheet http://clene.com/20260630/role/statement-note-16-geographic-and-segment-information-tables Note 16 - Geographic and Segment Information (Tables) Tables http://clene.com/20260630/role/statement-note-16-geographic-and-segment-information 37 false false R38.htm 995482 - Disclosure - Note 1 - Nature of the Business (Details Textual) Sheet http://clene.com/20260630/role/statement-note-1-nature-of-the-business-details-textual Note 1 - Nature of the Business (Details Textual) Details http://clene.com/20260630/role/statement-note-1-nature-of-the-business 38 false false R39.htm 995483 - Disclosure - Note 2 - Summary of Significant Accounting Policies (Details Textual) Sheet http://clene.com/20260630/role/statement-note-2-summary-of-significant-accounting-policies-details-textual Note 2 - Summary of Significant Accounting Policies (Details Textual) Details 39 false false R40.htm 995484 - Disclosure - Note 3 - Cash and Cash Equivalents - Available-for-sale Securities (Details) Sheet http://clene.com/20260630/role/statement-note-3-cash-and-cash-equivalents-availableforsale-securities-details Note 3 - Cash and Cash Equivalents - Available-for-sale Securities (Details) Details 40 false false R41.htm 995485 - Disclosure - Note 4 - Prepaid Expenses and Other Current Assets - Schedule of Prepaid Expenses and Other Current Assets (Details) Sheet http://clene.com/20260630/role/statement-note-4-prepaid-expenses-and-other-current-assets-schedule-of-prepaid-expenses-and-other-current-assets-details Note 4 - Prepaid Expenses and Other Current Assets - Schedule of Prepaid Expenses and Other Current Assets (Details) Details 41 false false R42.htm 995486 - Disclosure - Note 5 - Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) Sheet http://clene.com/20260630/role/statement-note-5-property-and-equipment-net-schedule-of-property-and-equipment-net-details Note 5 - Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) Details 42 false false R43.htm 995487 - Disclosure - Note 5 - Property and Equipment, Net - Schedule of Depreciation Expense (Details) Sheet http://clene.com/20260630/role/statement-note-5-property-and-equipment-net-schedule-of-depreciation-expense-details Note 5 - Property and Equipment, Net - Schedule of Depreciation Expense (Details) Details 43 false false R44.htm 995488 - Disclosure - Note 6 - Accrued Liabilities - Schedule of Accrued Liabilities (Details) Sheet http://clene.com/20260630/role/statement-note-6-accrued-liabilities-schedule-of-accrued-liabilities-details Note 6 - Accrued Liabilities - Schedule of Accrued Liabilities (Details) Details 44 false false R45.htm 995489 - Disclosure - Note 7 - Leases (Details Textual) Sheet http://clene.com/20260630/role/statement-note-7-leases-details-textual Note 7 - Leases (Details Textual) Details http://clene.com/20260630/role/statement-note-7-leases-tables 45 false false R46.htm 995490 - Disclosure - Note 7 - Leases - Maturity Analysis of Leases (Details) Sheet http://clene.com/20260630/role/statement-note-7-leases-maturity-analysis-of-leases-details Note 7 - Leases - Maturity Analysis of Leases (Details) Details 46 false false R47.htm 995491 - Disclosure - Note 7 - Leases - Components of Lease Cost (Details) Sheet http://clene.com/20260630/role/statement-note-7-leases-components-of-lease-cost-details Note 7 - Leases - Components of Lease Cost (Details) Details 47 false false R48.htm 995492 - Disclosure - Note 7 - Leases - Supplemental Cash Flow Information (Details) Sheet http://clene.com/20260630/role/statement-note-7-leases-supplemental-cash-flow-information-details Note 7 - Leases - Supplemental Cash Flow Information (Details) Details 48 false false R49.htm 995493 - Disclosure - Note 8 - Notes Payable and Convertible Notes Payable (Details Textual) Notes http://clene.com/20260630/role/statement-note-8-notes-payable-and-convertible-notes-payable-details-textual Note 8 - Notes Payable and Convertible Notes Payable (Details Textual) Details http://clene.com/20260630/role/statement-note-8-notes-payable-and-convertible-notes-payable-tables 49 false false R50.htm 995494 - Disclosure - Note 8 - Notes Payable and Convertible Notes Payable - Long-term Debt (Details) Notes http://clene.com/20260630/role/statement-note-8-notes-payable-and-convertible-notes-payable-longterm-debt-details Note 8 - Notes Payable and Convertible Notes Payable - Long-term Debt (Details) Details 50 false false R51.htm 995495 - Disclosure - Note 8 - Notes Payable and Convertible Notes Payable - Interest Expense (Details) Notes http://clene.com/20260630/role/statement-note-8-notes-payable-and-convertible-notes-payable-interest-expense-details Note 8 - Notes Payable and Convertible Notes Payable - Interest Expense (Details) Details 51 false false R52.htm 995496 - Disclosure - Note 8 - Notes Payable and Convertible Notes Payable - Schedule of Future Payments (Details) Notes http://clene.com/20260630/role/statement-note-8-notes-payable-and-convertible-notes-payable-schedule-of-future-payments-details Note 8 - Notes Payable and Convertible Notes Payable - Schedule of Future Payments (Details) Details 52 false false R53.htm 995497 - Disclosure - Note 9 - Commitments and Contingencies (Details Textual) Sheet http://clene.com/20260630/role/statement-note-9-commitments-and-contingencies-details-textual Note 9 - Commitments and Contingencies (Details Textual) Details http://clene.com/20260630/role/statement-note-9-commitments-and-contingencies 53 false false R54.htm 995498 - Disclosure - Note 10 - Income Taxes - Components of Income (Loss) Before Income Taxes (Details) Sheet http://clene.com/20260630/role/statement-note-10-income-taxes-components-of-income-loss-before-income-taxes-details Note 10 - Income Taxes - Components of Income (Loss) Before Income Taxes (Details) Details 54 false false R55.htm 995499 - Disclosure - Note 11 - Benefit Plans (Details Textual) Sheet http://clene.com/20260630/role/statement-note-11-benefit-plans-details-textual Note 11 - Benefit Plans (Details Textual) Details http://clene.com/20260630/role/statement-note-11-benefit-plans-tables 55 false false R56.htm 995500 - Disclosure - Note 11 - Benefit Plans - Stock-based Compensation Expense (Details) Sheet http://clene.com/20260630/role/statement-note-11-benefit-plans-stockbased-compensation-expense-details Note 11 - Benefit Plans - Stock-based Compensation Expense (Details) Details 56 false false R57.htm 995501 - Disclosure - Note 11 - Benefit Plans - Activity Related to Outstanding Stock Options (Details) Sheet http://clene.com/20260630/role/statement-note-11-benefit-plans-activity-related-to-outstanding-stock-options-details Note 11 - Benefit Plans - Activity Related to Outstanding Stock Options (Details) Details 57 false false R58.htm 995502 - Disclosure - Note 11 - Benefit Plans - Assumptions of Stock Options (Details) Sheet http://clene.com/20260630/role/statement-note-11-benefit-plans-assumptions-of-stock-options-details Note 11 - Benefit Plans - Assumptions of Stock Options (Details) Details 58 false false R59.htm 995503 - Disclosure - Note 12 - Fair Value (Details Textual) Sheet http://clene.com/20260630/role/statement-note-12-fair-value-details-textual Note 12 - Fair Value (Details Textual) Details http://clene.com/20260630/role/statement-note-12-fair-value-tables 59 false false R60.htm 995504 - Disclosure - Note 12 - Fair Value - Assets and Liabilities Measured on a Recurring Basis (Details) Sheet http://clene.com/20260630/role/statement-note-12-fair-value-assets-and-liabilities-measured-on-a-recurring-basis-details Note 12 - Fair Value - Assets and Liabilities Measured on a Recurring Basis (Details) Details 60 false false R61.htm 995505 - Disclosure - Note 12 - Fair Value - Unobservable Inputs (Details) Sheet http://clene.com/20260630/role/statement-note-12-fair-value-unobservable-inputs-details Note 12 - Fair Value - Unobservable Inputs (Details) Details 61 false false R62.htm 995506 - Disclosure - Note 13 - Capital Stock (Details Textual) Sheet http://clene.com/20260630/role/statement-note-13-capital-stock-details-textual Note 13 - Capital Stock (Details Textual) Details http://clene.com/20260630/role/statement-note-13-capital-stock-tables 62 false false R63.htm 995507 - Disclosure - Note 13 - Capital Stock - Outstanding Warrants (Details) Sheet http://clene.com/20260630/role/statement-note-13-capital-stock-outstanding-warrants-details Note 13 - Capital Stock - Outstanding Warrants (Details) Details 63 false false R64.htm 995508 - Disclosure - Note 14 - Net Loss Per Share - Computation of Basic and Diluted Net Income (Loss) Per Share (Details) Sheet http://clene.com/20260630/role/statement-note-14-net-loss-per-share-computation-of-basic-and-diluted-net-income-loss-per-share-details Note 14 - Net Loss Per Share - Computation of Basic and Diluted Net Income (Loss) Per Share (Details) Details 64 false false R65.htm 995509 - Disclosure - Note 14 - Net Loss Per Share - Antidilutive Securities Excluded from Computation (Details) Sheet http://clene.com/20260630/role/statement-note-14-net-loss-per-share-antidilutive-securities-excluded-from-computation-details Note 14 - Net Loss Per Share - Antidilutive Securities Excluded from Computation (Details) Details 65 false false R66.htm 995510 - Disclosure - Note 15 - Related Party Transactions (Details Textual) Sheet http://clene.com/20260630/role/statement-note-15-related-party-transactions-details-textual Note 15 - Related Party Transactions (Details Textual) Details http://clene.com/20260630/role/statement-note-15-related-party-transactions-tables 66 false false R67.htm 995511 - Disclosure - Note 15 - Related Party Transactions - Revenue From 4Life Agreement (Details) Sheet http://clene.com/20260630/role/statement-note-15-related-party-transactions-revenue-from-4life-agreement-details Note 15 - Related Party Transactions - Revenue From 4Life Agreement (Details) Details 67 false false R68.htm 995512 - Disclosure - Note 16 - Geographic and Segment Information - Profit and Loss Information by Reportable Segment (Details) Sheet http://clene.com/20260630/role/statement-note-16-geographic-and-segment-information-profit-and-loss-information-by-reportable-segment-details Note 16 - Geographic and Segment Information - Profit and Loss Information by Reportable Segment (Details) Details 68 false false R69.htm 995513 - Disclosure - Note 16 - Geographic and Segment Information - Reconciliation of the Reportable Segments' Loss From Operations to Consolidated (Details) Sheet http://clene.com/20260630/role/statement-note-16-geographic-and-segment-information-reconciliation-of-the-reportable-segments-loss-from-operations-to-consolidated-details Note 16 - Geographic and Segment Information - Reconciliation of the Reportable Segments' Loss From Operations to Consolidated (Details) Details 69 false false R70.htm 995514 - Disclosure - Note 16 - Geographic and Segment Information - Assets by Reportable Segment (Details) Sheet http://clene.com/20260630/role/statement-note-16-geographic-and-segment-information-assets-by-reportable-segment-details Note 16 - Geographic and Segment Information - Assets by Reportable Segment (Details) Details 70 false false All Reports Book All Reports clnn-20260630.xsd clnn-20260630_cal.xml clnn-20260630_def.xml clnn-20260630_lab.xml clnn-20260630_pre.xml clnn20260630_10q.htm pipelinemay2026_24.jpg http://fasb.org/us-gaap/2026 http://xbrl.sec.gov/dei/2026 http://xbrl.sec.gov/ecd/2026 true true