Organization, Consolidation and Presentation of Financial Statements (Policies)	9 Months Ended
	Jun. 30, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim information, and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X promulgated by the SEC. Accordingly, they do not include all information and notes required by U.S. GAAP for annual financial statements. In our opinion, the interim financial statements reflect all adjustments, which are all normal recurring adjustments, that are necessary to provide a fair presentation of the financial results for the interim periods presented. Operating results for interim periods are not necessarily indicative of results that may be expected for an entire fiscal year. The condensed consolidated balance sheet as of September 30, 2021 has been derived from the audited consolidated financial statements as of such date. For a more complete understanding of our business, financial position, operating results, cash flows, risk factors and other matters, please refer to our Annual Report on Form 10-K for the fiscal year ended September 30, 2021.
Significant Accounting Policies and Estimates	Significant Accounting Policies and Estimates Pension Plan With the acquisition of S&N, we acquired the assets and assumed the liabilities associated with a pension plan, now named the Emcore Space & Navigation Corporation Pension Plan (the “Pension Plan”), which is a defined benefit pension plan providing postretirement benefits to certain employees. Subsequent to quarter end, as of July 1, 2022, the Pension Plan was amended to freeze benefit plan accruals for participants. The investments in the Pension Plan are measured at fair value using quoted market prices or the net asset value per share as a practical expedient. The projected benefit obligations associated with the Pension Plan are determined based on actuarial models utilizing mortality tables and discount rates applied to the expected benefit term. The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities, as of the date of the financial statements, and the reported amounts of revenue and expenses during the reported period. If these estimates differ significantly from actual results, the impact to the condensed consolidated financial statements may be material.
Recent Accounting Pronouncements	Recent Accounting Pronouncements We recently adopted the following accounting standards, which had the following impacts on our condensed consolidated financial statements: In December 2019, the FASB issued Accounting Standards Update (“ASU”) 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which simplifies the accounting for income taxes by removing various exceptions, such as the exception to the incremental approach for intra-period tax allocation when there is a loss from continuing operations and income or a gain from other items. The amendments in this update also simplify the accounting for income taxes related to income-based franchise taxes and require that an entity reflect enacted tax laws or rates in the annual effective tax rate computation in the interim period that includes the enactment date. The new standard was effective for our fiscal year beginning October 1, 2021. The adoption of this new standard did not have a material impact on the condensed consolidated financial statements. In October 2021, the FASB issued ASU 2021-08, Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers, which provides an exception to fair value measurement for contract assets and contract liabilities related to revenue contracts acquired in a business combination. The ASU required an entity (acquirer) to recognize and measure contract assets and contract liabilities acquired in a business combination in accordance with Topic 606. At the acquisition date, an acquirer should account for the related revenue contracts in accordance with Topic 606 as if it had originated the contract. The ASU is effective for the Company for our annual and interim periods beginning October 1, 2023. We early adopted this standard effective with our fiscal year beginning October 1, 2021. The early adoption of this new standard did not have a material impact on the condensed consolidated financial statements. Other accounting standards that have been issued or proposed by FASB and do not require adoption until a future date are not expected to have a material impact on the consolidated financial statements upon adoption. The Company does not discuss recent pronouncements that are not anticipated to have an impact on or are unrelated to its financial condition, results of operations, cash flows, or disclosures.
Legal Costs	Professional legal fees are expensed when incurred. We accrue for contingent losses when such losses are probable and reasonably estimable.