Significant Accounting Policies (Policies)	6 Months Ended
Significant Accounting Policies (Policies)	Mar. 31, 2018
Accounting Policies [Abstract]
Basis of Accounting, Policy [Policy Text Block]	General The Company’s unaudited interim condensed consolidated financial statements included herein have been prepared in accordance with the instructions to Form 10 -Q and Article 8 of Regulation S- X and the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles have been condensed or omitted pursuant to such rules and regulations. In management’s opinion, the accompanying statements reflect adjustments necessary to present fairly the financial position, results of operations, and cash flows for those periods indicated, and contain adequate disclosure to make the information presented not misleading. Adjustments included herein are of a normal, recurring nature unless otherwise disclosed in the footnotes. The condensed consolidated financial statements and notes thereto should be read in conjunction with the Company’s audited financial statements and notes thereto for the year ended September 30, 2017 included in the Company’s Annual Report on Form 10 -K, as filed with the SEC on December 13, 2017. The accompanying condensed consolidated balance sheet at September 30, 2017 has been derived from the audited consolidated balance sheet at September 30, 2017 contained in the above referenced Form 10 -K. Results of operations for interim periods are not necessarily indicative of the results of operations for a full year.
Consolidation, Policy [Policy Text Block]	Principles of Consolidation The Company has four wholly owned subsidiaries, Genasys Holding, S.L. and Genasys II Spain, S.A.U. and two currently inactive subsidiaries, Genasys America de CV and LRAD International Corporation. The condensed consolidated financial statements include the accounts of these subsidiaries after elimination of intercompany transactions and accounts.
Reclassification, Policy [Policy Text Block]	Reclassifications Where necessary, the prior year’s information has been reclassified to conform to the current year presentation.
New Accounting Pronouncements, Policy [Policy Text Block]	In November 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2016 - 18, Statement of Cash Flows (Topic 230 ), Restricted Cash ("ASU 2016 - 18" ), which amends Topic 230 to add or clarify guidance on the classification and presentation of restricted cash in the statement of cash flows. The standard requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The provisions of this guidance are to be applied using a retrospective transition method to each period presented. ASU 2016 - 18 is effective for annual reporting periods beginning after December 15, 2017, and interim periods within those years, with early adoption permitted. The Company adopted ASU 2016 - 18 effective January 1, 2018. For the six months ended March 31, 2018, the increase in restricted cash resulted primarily from restricted cash balances included in the assets acquired in the acquisition of Genasys, as described in Note 4. The adoption did not have a material impact on the Company's consolidated financial position, results of operations and cash flows, other than the impact discussed above. In March 2016, the FASB issued ASU No. 2016 - 09, Compensation – Stock Compensation (Topic 718 ): Improvements to Employee Share-Based Payment Accounting . This guidance changes how companies account for certain aspects of share-based payments to employees. Among other things, under the new guidance, companies will no longer record excess tax benefits and certain tax deficiencies in additional paid-in-capital (“APIC”), but will instead record such items as income tax expense or benefit in the income statement, and APIC pools will be eliminated. Companies will apply this guidance prospectively. Another component of the new guidance allows companies to make an accounting policy election for the impact of forfeitures on the recognition of expense for share-based payment awards, whereby forfeitures can be estimated, as required today, or recognized when they occur. If elected, the change to recognize forfeitures when they occur needs to be adopted using a modified retrospective approach. The guidance was effective for the Company in the first quarter of fiscal 2018. The adoption of this standard resulted in the recognition of $1.1 million of gross deferred tax assets related to the historical excess tax benefits from stock-based compensation that was not previously included in deferred tax assets and a corresponding increase in the Company’s valuation allowance. In February 2016, the FASB issued ASU 2016 - 02, Leases (Topic 842 ) , which issued new guidance related to leases that outlines a comprehensive lease accounting model and supersedes the current lease guidance. The new guidance requires lessees to recognize lease liabilities and corresponding right-of-use assets for all leases with lease terms of greater than 12 months. It also changes the definition of a lease and expands the disclosure requirements of lease arrangements. The new guidance must be adopted using the modified retrospective approach and will be effective for the Company in the fiscal year beginning October 1, 2019. Early adoption is permitted. The Company is currently evaluating the impact of this guidance, if any, on its consolidated financial statements and related disclosures. In May 2014, the FASB issued ASU No. 2014 - 09, Revenue from Contracts with Customers (“ASU 2014 - 09” ), which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. ASU 2014 - 09 will replace most existing revenue recognition guidance in U.S. generally accepted accounting principles when it becomes effective. In July 2015, the FASB deferred the effective date of the standard by an additional year; however, it provided companies the option to adopt one year earlier, commensurate with the original effective date. Accordingly, the standard will be effective for the Company in the fiscal year beginning October 1, 2018. The Company is currently evaluating the impact of this guidance, if any, on its consolidated financial statements and related disclosures.