Organization and Going Concern	12 Months Ended
Organization and Going Concern	Dec. 31, 2025
Organization and Going Concern [Abstract]
Organization and Going Concern	Note 1 – Organization and Going Concern AmBase Corporation (the “Company” or “AmBase”) is a Delaware corporation that was incorporated in 1975. AmBase is a holding company. At December 31, 2025, the Company’s assets consisted of cash and cash equivalents. The Company is engaged in the management of its assets and liabilities. In June 2013, the Company purchased an equity interest in a real estate development property through a joint venture agreement to purchase and develop real property located at 105 through 111 West 57^th Street in New York, New York (the “111 West 57^th Property”). The Company is engaged in material disputes and litigation with regard to the 111 West 57^th Property. Despite ongoing litigation challenging the legitimacy of the actions taken in connection with the “Strict Foreclosure”, (as defined and as further discussed herein), the Company recorded an impairment for the full amount of its equity investment in the 111 West 57th Property in 2017. Prior to the Strict Foreclosure, the carrying value of the Company’s equity investment in the 111 West 57^th Property represented a substantial portion of the Company’s assets and net equity value. For additional information regarding the Company’s recording of an impairment of its equity investment in the 111 West 57^th Property and the Company’s legal proceedings relating to the 111 West 57^th Property, including the Company’s challenge to the Strict Foreclosure, see Note 3 and Note 8. A fundamental principle of the preparation of financial statements in accordance with GAAP is the assumption that an entity will continue in existence as a going concern, which contemplates continuity of operations and the realization of assets and settlement of liabilities occurring in the ordinary course of business. In accordance with this requirement, the Company has prepared its accompanying consolidated financial statements assuming the Company will continue as a going concern. The Company has incurred operating losses and used cash for operating activities for the past several years. The Company has continued to keep operating expenses at a reduced level; however, there can be no assurance that the Company’s current level of operating expenses will not increase or that other uses of cash will not be necessary. The Company believes that based on its current level of operating expenses, its existing cash and cash equivalents may not be sufficient to cover operating cash needs through the twelve month period from the financial statement reporting date. Based on the above factors, management determined there is substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued. The accompanying consolidated financial statements have been prepared assuming that the Company will continue as a going concern. The financial statements do not include adjustments to the carrying value of assets and liabilities, which might be necessary should the Company not continue in operation. In order to continue as a going concern and fund anticipated future litigation expenses, the Company will need to raise additional capital. The Company continues to explore all possible strategic alternatives to meet is capital needs, including but not limited to, raising additional capital through the sale of equity or debt securities or long-term borrowings, which may include additional borrowings from management and/or affiliates of the Company, financial institutions or other stockholders of the Company, litigation funding agreements from management and/or affiliates of the Company, financial institutions, other stockholders of the Company, or other third parties, or any combination thereof, and seeking recoveries from various sources. The Company intends for any sales of debt or equity securities or any borrowings from any parties to be on market terms to be agreed upon at the time of any transaction. However, there can be no assurance that the Company will be able to raise capital or obtain financing on terms acceptable to the Company, if at all. While the Company’s management is evaluating future courses of action to protect and/or recover the value of the Company’s equity investment in the 111 West 57^th Property, the adverse developments make it uncertain as to whether any such courses of action will be successful. Any such efforts are likely to require sustained effort over a period of time and substantial additional capital. Inability to recover all or most of such value would, in all likelihood, have a material adverse effect on the Company’s financial condition and future prospects. The Company can give no assurances with regard if it will prevail with respect to any of its claims. As noted above, the Company continues to explore all possible strategic alternatives to meet its capital needs. Litigation funding agreements are special types of financing arrangements that generally are structured so that the litigation funder would receive back their initial funding amount first (i.e. before any recovery is received by the Company), plus an additional multiple ranging from 1.0 times to 3.5 times the amount funded (depending on various factors), plus depending on the funder, additional fees, expenses, interest and potentially an additional percentage of the total recovery received. If the Company continues to source capital through one or more litigation funding agreements, there can be no assurance that the Company would be able to secure any such additional litigation funding on acceptable terms or at all. In order to provide the necessary cash resources to continue operations and continue the litigation related to the 111 West 57th Property, and pay amounts currently owed, on March 2, 2026, the Company entered into litigation funding agreements with Mr. Richard A. Bianco, the Company’s Chairman, President and Chief Executive Officer (“Mr. R.A. Bianco” or “RAB”) and BARC Investments LLC (“BARC”). As part of those litigation funding agreements, the Company shall distribute any consideration it actually receives in connection with the 111 West 57^th legal proceedings in accordance with the terms of the litigation funding agreements which will therefore further reduce the Company’s share of any future litigation proceeds. For additional information, see Note 12. On April 1, 2024, the Company completed the issuance and sale, of the shares of the Company’s common stock (the “Shares”) in the private placement offering (the “Equity Offering”) on the previously disclosed terms and conditions, including Shares purchased by an institutional investor not affiliated with the Company and Shares purchased by BARC Investments, LLC, an affiliate of the Company owned and controlled by two of the Company’s directors and their sibling. The offer and sale of the Shares in the Equity Offering was completed in reliance on the exemption from registration under Rule 506(c) of Regulation D promulgated under Section 4(a)(2) of the Securities Act of 1933, as amended. See Note 5 for additional information.