Organization	12 Months Ended
Dec. 31, 2013
Organization [Abstract]
Organization	Note 1 - Organization AmBase Corporation ("AmBase" or the "Company") is a holding company which has an equity investment in a real estate development property to develop real property in New York, New York and through a wholly owned subsidiary, owns a commercial office building in Greenwich, Connecticut that is managed and operated by the Company. The Company was a plaintiff in a legal proceeding, commenced in 1993, seeking recovery of damages from the United States Government for the loss of the Company's wholly-owned subsidiary, Carteret Savings Bank, F.A. (the "Supervisory Goodwill" legal proceedings). The Supervisory Goodwill legal proceedings were settled in October 2012, pursuant to a Settlement Agreement between the Company, the Federal Deposit Insurance Corporation-Receiver ("FDIC-R") and the Department of Justice ("DOJ") on behalf of the United States of America (the "United States"), (the "Settlement Agreement") as approved by the United States Court of Federal Claims (the "Court of Federal Claims"). As part of the Settlement Agreement in the Company's Supervisory Goodwill legal proceedings, the Company is entitled to a tax gross-up in an amount to be determined if and when any federal taxes should be imposed on the Settlement Amount. See Notes 10 and 11 for a discussion of the Supervisory Goodwill tax gross-up matters relating to the Settlement Agreement. The Company's assets currently consist primarily of cash and cash equivalents, investment securities, an equity investment in a real estate development property, an indemnification asset, and real estate owned. The Company earns non-operating revenue consisting principally of investment earnings on investment securities and cash equivalents. As further discussed in Note 5, in June 2013, the Company, through a newly formed subsidiary, 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 57th Street in New York, New York (the "111 West 57th Property"). The Company continues to evaluate a number of possible acquisitions and is engaged in the management of its assets and liabilities, including the contingent assets associated with its legal claims. Discussions and negotiations are ongoing with respect to certain of these matters. From time to time, the Company and its subsidiaries may be named as a defendant in various lawsuits or proceedings. The Company intends to aggressively contest all litigation and contingencies, as well as pursue all sources for contributions to settlements. For a discussion of lawsuits and proceedings, including a discussion of the Supervisory Goodwill Settlement Agreement – Tax Gross-up see Notes 10 and 11.

Organization

12 Months Ended

Dec. 31, 2013

Note 1 - Organization

AmBase Corporation ("AmBase" or the "Company") is a holding company which has an equity investment in a real estate development property to develop real property in New York, New York and through a wholly owned subsidiary, owns a commercial office building in Greenwich, Connecticut that is managed and operated by the Company.

The Company was a plaintiff in a legal proceeding, commenced in 1993, seeking recovery of damages from the United States Government for the loss of the Company's wholly-owned subsidiary, Carteret Savings Bank, F.A. (the "Supervisory Goodwill" legal proceedings). The Supervisory Goodwill legal proceedings were settled in October 2012, pursuant to a Settlement Agreement between the Company, the Federal Deposit Insurance Corporation-Receiver ("FDIC-R") and the Department of Justice ("DOJ") on behalf of the United States of America (the "United States"), (the "Settlement Agreement") as approved by the United States Court of Federal Claims (the "Court of Federal Claims"). As part of the Settlement Agreement in the Company's Supervisory Goodwill legal proceedings, the Company is entitled to a tax gross-up in an amount to be determined if and when any federal taxes should be imposed on the Settlement Amount. See Notes 10 and 11 for a discussion of the Supervisory Goodwill tax gross-up matters relating to the Settlement Agreement.

The Company's assets currently consist primarily of cash and cash equivalents, investment securities, an equity investment in a real estate development property, an indemnification asset, and real estate owned. The Company earns non-operating revenue consisting principally of investment earnings on investment securities and cash equivalents. As further discussed in Note 5, in June 2013, the Company, through a newly formed subsidiary, 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 57th Street in New York, New York (the "111 West 57th Property"). The Company continues to evaluate a number of possible acquisitions and is engaged in the management of its assets and liabilities, including the contingent assets associated with its legal claims. Discussions and negotiations are ongoing with respect to certain of these matters. From time to time, the Company and its subsidiaries may be named as a defendant in various lawsuits or proceedings. The Company intends to aggressively contest all litigation and contingencies, as well as pursue all sources for contributions to settlements. For a discussion of lawsuits and proceedings, including a discussion of the Supervisory Goodwill Settlement Agreement – Tax Gross-up see Notes 10 and 11.