Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] | Note 1. Basis of Presentation In the opinion of management, the accompanying unaudited condensed consolidated financial statements contain all adjustments necessary to present fairly American Shared Hospital Services’ consolidated financial position as of June 30, 2018 and the results of its operations for the three and six-month periods ended June 30, 2018 and 2017, which results are not necessarily indicative of results on an annualized basis. Consolidated balance sheet amounts as of December 31, 2017 have been derived from audited consolidated financial statements. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements for the year ended December 31, 2017 included in the Company’s 10-K filed with the Securities and Exchange Commission. These consolidated financial statements include the accounts of American Shared Hospital Services and its subsidiaries (the “Company”) as follows: the Company wholly-owns the subsidiaries American Shared Radiosurgery Services (“ASRS”), PBRT Orlando, LLC (“Orlando”), OR21, Inc., and MedLeader.com, Inc. (“MedLeader”); the Company is the majority owner of Long Beach Equipment, LLC (“LBE”); ASRS is the majority-owner of GK Financing, LLC (“GKF”) which wholly-owns the subsidiaries Instituto de Gamma Knife del Pacifico S.A.C. (“GKPeru”) and GK Financing U.K., Limited (“GKUK”); GKF is the majority owner of the subsidiaries Albuquerque GK Equipment, LLC (“AGKE”) and Jacksonville GK Equipment, LLC (“JGKE”). The Company (through ASRS) and Elekta AB, the manufacturer of the Gamma Knife (through its wholly-owned United States subsidiary, GKV Investments, Inc.), entered into an operating agreement and formed GKF. As of June 30, 2018, GKF provided Gamma Knife units to fifteen medical centers in the United States in the states of Arkansas, California, Florida, Illinois, Massachusetts, Mississippi, Nebraska, Nevada, New Mexico, Tennessee, Ohio, Oregon, and Texas. GKF also owns and operates a single-unit Gamma Knife facility in Lima, Peru. The Company through its wholly-owned subsidiary, Orlando, provided proton beam radiation therapy (“PBRT”) and related equipment to a customer in the United States. The Company also directly provides radiation therapy and related equipment, including Intensity Modulated Radiation Therapy (“IMRT”), Image Guided Radiation Therapy (“IGRT”) and a CT Simulator to the radiation therapy department at an existing Gamma Knife site in Massachusetts. The Company formed the subsidiaries GKPeru and GKUK for the purposes of expanding its business internationally into Peru and the United Kingdom, respectively; Orlando and LBE to provide proton beam therapy equipment and services in Orlando, Florida and Long Beach, California; and AGKE and JGKE to provide Gamma Knife services in Albuquerque, New Mexico and Jacksonville, Florida, respectively. AGKE began operations in the second quarter of 2011 and JGKE began operations in the fourth quarter of 2011. Orlando began operations in April 2016. GKPeru treated its first patient in July 2017. GKUK is inactive and LBE is not expected to generate revenue within the next two years. The Company continues to develop its design and business model for “The Operating Room for the 21st Century” SM MedLeader was formed to provide continuing medical education online and through videos for doctors, nurses, and other healthcare workers. This subsidiary is not operational at this time. All significant intercompany accounts and transactions have been eliminated in consolidation. Based on the guidance provided in accordance with Accounting Standards Codification (“ASC”) 280 Segment Reporting In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers (Topic 606) , ( 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. The ASU replaced most existing revenue recognition guidance in United States Generally Accepted Accounting Principles (“GAAP”). In December 2016, FASB issued ASU 2016-20 Technical Corrections and Improvements to Topic 606 Leases The Company adopted ASU 2014-09 as of January 1, 2018 using the modified retrospective method. The cumulative effect of adopting ASU 2014-09 did not have a material impact on retained earnings, as reported by the Company, and there was no change to the Company’s IT environment following adoption. Under ASU 2014-09, the Company determined that, as it relates to the stand-alone facility in Lima, Peru, a contract exists between GKPeru and the individual patient treated at the facility. The Company acts as the principal in this transaction and provides, at a point in time, a single performance obligation, in the form of a Gamma Knife treatment. Revenue related to a Gamma Knife treatment is recognized on a gross basis in the month the patient receives treatment. There is no variable consideration present in the Company’s performance obligation and the transaction price is agreed upon per the stated contractual rate. Payment terms are typically prepaid for self-pay patients and insurance provider payments are paid net 30 days. The Company did not capitalize any incremental costs related to the fulfillment of its customer contracts. Accounts receivable and revenues earned by GKPeru were not material for the six-month period ended June 30, 2018, therefore, no additional disclosures have been made at this time. In February 2016, the FASB issued ASU 2016-02 which requires lessees to recognize, for all leases, at the commencement date, a lease liability, and a right-of-use asset. Under the new guidance, lessor accounting is largely unchanged. The new guidance is effective for the Company on January 1, 2019. Early adoption is permitted. The Company is evaluating the effect that ASU 2016-02 will have on its consolidated financial statements and related disclosures. The Company performed an analysis to determine if its revenue agreements with customers fall under the scope of ASU 2016-02 or ASU 2014-09 and concluded that, other than with respect to the Company’s stand-alone facility in Lima, Peru, ASU 2016-02 applied. The Company believes it is following an appropriate timeline to allow for proper recognition, presentation, and disclosure upon adoption of ASU 2016-02. In June 2016, the FASB issued ASU No. 2016 Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which requires measurement and recognition of expected credit losses for financial assets held. The new guidance is effective for fiscal periods beginning after December 15, 2018. The Company does not expect ASU 2016- on In February 2018, the FASB issued ASU No. 2018-03 Recognition and Measurement of Financial Assets and Financial Liabilities In July 2018, the FASB issued ASU No. 2018-09, Codification Improvements |