Organization	12 Months Ended
Dec. 31, 2012
Organization [Abstract]
Organization	Note 1 - Organization AmBase Corporation ("AmBase" or the "Company") is a holding company which, through a wholly owned subsidiary, owns a commercial office building in Greenwich, Connecticut. The Company previously owned an insurance company and a savings bank. In February 1991, the Company sold its ownership interest in The Home Insurance Company and its subsidiaries. On December 4, 1992, Carteret Savings Bank, FA was placed in receivership by the Office of Thrift Supervision ("OTS"). On October 11, 2012, the United States Court of Federal Claims (the "Court of Federal Claims") issued an order approving the Settlement Agreement in the Supervisory Goodwill legal proceedings between AmBase, 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 was subject to approval by the Court of Federal Claims. On October 19, 2012, the United States paid $180,650,000 (one hundred eighty million, six hundred fifty thousand dollars) directly to AmBase. As part of the Settlement Agreement, the Company is also 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. The Company has no contingent fee agreements in place with its attorneys or any outside advisor in connection with the Supervisory Goodwill legal proceedings or award. For additional information see Notes 9 and 10. The Company currently earns non-operating revenue consisting principally of investment earnings on investment securities and cash equivalents. 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, as described in Notes 9 and 10. 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.

Organization

12 Months Ended

Dec. 31, 2012

Note 1 - Organization

AmBase Corporation ("AmBase" or the "Company") is a holding company which, through a wholly owned subsidiary, owns a commercial office building in Greenwich, Connecticut. The Company previously owned an insurance company and a savings bank.

In February 1991, the Company sold its ownership interest in The Home Insurance Company and its subsidiaries. On December 4, 1992, Carteret Savings Bank, FA was placed in receivership by the Office of Thrift Supervision ("OTS").

On October 11, 2012, the United States Court of Federal Claims (the "Court of Federal Claims") issued an order approving the Settlement Agreement in the Supervisory Goodwill legal proceedings between AmBase, 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 was subject to approval by the Court of Federal Claims. On October 19, 2012, the United States paid $180,650,000 (one hundred eighty million, six hundred fifty thousand dollars) directly to AmBase. As part of the Settlement Agreement, the Company is also 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. The Company has no contingent fee agreements in place with its attorneys or any outside advisor in connection with the Supervisory Goodwill legal proceedings or award. For additional information see Notes 9 and 10.

The Company currently earns non-operating revenue consisting principally of investment earnings on investment securities and cash equivalents. 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, as described in Notes 9 and 10. 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.