Organization (Policies)	6 Months Ended
Mar. 31, 2023
Accounting Policies [Abstract]
Business Description and Basis of Presentation [Text Block]	Description of Business Surmodics, Inc. and subsidiaries (referred to as “Surmodics,” the “Company,” “we,” “us,” “our” and other like terms) is a leading provider of performance coating technologies for intravascular medical devices and chemical and biological components for in vitro diagnostic (“IVD”) immunoassay tests and microarrays. Surmodics develops and commercializes highly differentiated vascular intervention medical devices that are designed to address unmet clinical needs and engineered to the most demanding requirements. This key growth strategy leverages the combination of the Company’s expertise in proprietary surface modification and drug-delivery coating technologies, along with its device design, development and manufacturing capabilities. The Company’s mission is to improve the detection and treatment of disease. Surmodics is headquartered in Eden Prairie, Minnesota.
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The accompanying unaudited condensed consolidated financial statements include all accounts and wholly-owned subsidiaries and have been prepared in accordance with accounting principles generally accepted in the U.S. (“GAAP”). All intercompany transactions have been eliminated. The Company operates on a fiscal year ending on September 30. In accordance with the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”), the Company has omitted footnote disclosures that would substantially duplicate the disclosures contained in the audited consolidated financial statements of the Company. These unaudited condensed consolidated financial statements should be read together with the audited consolidated financial statements for the fiscal year ended September 30, 2022, and notes thereto included in our Annual Report on Form 10-K as filed with the SEC.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Ultimate results could differ from those estimates. The results of operations for the three and six months ended March 31, 2023 are not necessarily indicative of the results that may be expected for the entire 2023 fiscal year. Certain reclassifications have been made to the prior year's consolidated financial statements to conform to the current year presentation.
New Accounting Pronouncements	New Accounting Pronouncements No new accounting pronouncement issued or effective has had, or is expected to have, a material impact on the Company’s condensed consolidated financial statements.
Net Loss Per Share Data	Basic net loss per common share is calculated by dividing net loss by the weighted average number of common shares outstanding during the period. Diluted net loss per common share is computed by dividing net loss by the weighted average number of common and common equivalent shares outstanding during the period. The Company’s potentially dilutive common shares are those that result from dilutive common stock options and non-vested stock relating to restricted stock awards and restricted stock units. The calculation of diluted loss per share excluded 0.1 million in weighted-average shares for each of the three months ended March 31, 2023 and 2022 and 0.1 million and 0.2 million weighted-average shares for the six months ended March 31, 2023 and 2022, respectively, as their effect was anti-dilutive as a result of the net loss incurred for those periods. Therefore, diluted weighted average number of shares outstanding and diluted net loss per share were the same as basic weighted average number of shares outstanding and net loss per share for the three and six months ended March 31, 2023 and 2022.
Income Taxes	For interim income tax reporting, the Company estimates its annual effective tax rate and applies it to fiscal year-to-date pretax loss, excluding unusual or infrequently occurring discrete items. Tax jurisdictions with losses for which tax benefits cannot be realized are excluded.
Income Tax Uncertainties	The Company files income tax returns, including returns for its subsidiaries, in the U.S. federal jurisdiction and in various state jurisdictions, as well as several non-U.S. jurisdictions. Uncertain tax positions are related to tax years that remain subject to examination. The Internal Revenue Service commenced an examination of the Company’s fiscal 2019 U.S. federal tax return in fiscal 2022; the examination has not been completed. U.S. federal income tax returns for years prior to fiscal 2019 are no longer subject to examination by federal tax authorities. For tax returns for U.S. state and local jurisdictions, the Company is no longer subject to examination for tax years generally before fiscal 2012. For tax returns for non-U.S. jurisdictions, the Company is no longer subject to income tax examination for years prior to 2018. Additionally, the Company has been indemnified of liability for any taxes relating to Creagh Medical, Ltd.; NorMedix, Inc.; and Vetex for periods prior to the respective acquisition dates, pursuant to the terms of the related share purchase agreements.

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