Organization and Basis of Presentation	9 Months Ended
Organization and Basis of Presentation	Sep. 30, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation Organization Flagstar Financial, Inc. was organized under Delaware law on July 20, 1993, and, prior to the completion of the Reorganization (as defined below) on October 17, 2025, was the holding company for Flagstar Bank, N.A. (hereinafter referred to as the “Bank”). We are headquartered in Hicksville, New York with regional headquarters in Troy, Michigan. Prior to the completion of the Reorganization (as defined below) on October 17, 2025, Flagstar Financial, Inc. was subject to regulation, examination and supervision by the Federal Reserve. The Bank is a National Association, subject to federal regulation and oversight by the OCC. Following the elimination of Flagstar Financial, Inc. as a result of the completion of the Reorganization, effective as of October 17, 2025, our only primary federal banking regulator is the OCC. We operate approximately 340 locations across nine states, with strong footholds in the greater New York/New Jersey metropolitan region and in the upper Midwest, along with a significant presence in fast-growing markets in Florida and the West Coast. Effective October 17, 2025, the Bank became the successor reporting company to Flagstar Financial, Inc. pursuant to an internal corporate reorganization to eliminate the Bank’s holding company structure (the “Reorganization”). In connection with the completion of the transaction, Flagstar Financial, Inc. was merged with and into the Bank (the “Merger”), with the Bank continuing as the surviving entity. The Bank’s common stock, as well as depositary shares representing interests in the Bank's Series A preferred stock and the BONUSES Units, was registered with the Bank’s primary banking regulator, the OCC, under the Securities Exchange Act of 1934, as amended, and will be subject to federal regulation and oversight by the OCC. As part of the Reorganization, the Bank increased the authorized number of common shares by 250 million shares which can be used for general corporate purposes. The Bank assumed Flagstar Financial, Inc.'s debt obligations, equity incentive plans, equity compensation plans, and other compensation plans as a result of the Merger. Additionally, immediately after the Merger, the Bank had substantially the same consolidated assets, liabilities, and stockholders' equity as Flagstar Financial, Inc.immediately prior to the Merger. Basis of Presentation The accompanying condensed consolidated financial statements include our accounts and other entities in which we have a controlling financial interest. Our accompanying financial statements conform to GAAP and to general practices within the banking industry. The preparation of financial statements in conformity with GAAP requires us to make estimates and judgments that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. The condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes included on our Form 10-K for the year ended December 31, 2024. Except for per share or otherwise specified amounts, all amounts presented within the tables below are stated in millions. All inter-company accounts and transactions are eliminated in consolidation. We currently have certain unconsolidated subsidiaries in the form of wholly-owned statutory business trusts, which were formed to issue guaranteed capital securities. See "Note 9 - Borrowed Funds,” for additional information regarding these trusts. When necessary, certain reclassifications have been made to prior-year amounts to conform to the current-year presentation.