Description of Business, Organization and Basis of Presentation	12 Months Ended
Dec. 31, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business, Organization and Basis of Presentation	Description of Business, Organization and Basis of Presentation Organization Flagstar Bank, National Association was organized under Delaware law on July 20, 1993. Throughout this report we refer to Flagstar Bank, National Association and its consolidated subsidiaries in a simplified and collective manner, using words like "we," "our," "us" and "the Bank." We are headquartered in Hicksville, New York with regional headquarters in Troy, Michigan. We are subject to regulation and oversight by the Office of the Comptroller of the Currency. We currently 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 California. 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 Reorganization, 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, were registered with the Bank’s primary banking regulator, the OCC, under the Securities Exchange Act of 1934, as amended, and are subject to federal regulation and oversight by the OCC. 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 consolidated financial statements include the accounts of the Bank and other entities in which the Bank has a controlling financial interest. We prepare these consolidated financial statements in accordance with GAAP. All inter-company accounts and transactions are eliminated in consolidation. The Bank currently has certain unconsolidated subsidiaries in the form of wholly-owned statutory business trusts, which were formed to issue guaranteed capital securities. See Note 12 - 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. We have also considered the impact of subsequent events on these consolidated financial statements through the date of issuance of the consolidated financial statements. Except for per share or otherwise specified amounts, all amounts presented within the tables below are stated in millions. Use of Estimates We prepare these consolidated financial statements using financial information available at the time of preparation, which requires us to make estimates that affect the amounts reported. These estimates require the use of judgments and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses in the periods presented. We believe that the estimates employed are appropriate and the resulting balances are reasonable; however, due to inherent uncertainties in making estimates, actual results could differ from the original estimates, requiring adjustments to these balances in future periods. Our most significant estimate relates to the ACL.

Flagstar Bank, National Association was organized under Delaware law on July 20, 1993. Throughout this report we refer to Flagstar Bank, National Association and its consolidated subsidiaries in a simplified and collective manner, using words like "we," "our," "us" and "the Bank."

We are headquartered in Hicksville, New York with regional headquarters in Troy, Michigan. We are subject to regulation and oversight by the Office of the Comptroller of the Currency. We currently 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 California.

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 Reorganization, 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, were registered with the Bank’s primary banking regulator, the OCC, under the Securities Exchange Act of 1934, as amended, and are subject to federal regulation and oversight by the OCC.

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.

The accompanying consolidated financial statements include the accounts of the Bank and other entities in which the Bank has a controlling financial interest. We prepare these consolidated financial statements in accordance with GAAP. All inter-company accounts and transactions are eliminated in consolidation. The Bank currently has certain unconsolidated subsidiaries in the form of wholly-owned statutory business trusts, which were formed to issue guaranteed capital securities. See Note 12 - Borrowed Funds, for additional information regarding these trusts.

We have also considered the impact of subsequent events on these consolidated financial statements through the date of issuance of the consolidated financial statements.

We prepare these consolidated financial statements using financial information available at the time of preparation, which requires us to make estimates that affect the amounts reported. These estimates require the use of judgments and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses in the periods presented. We believe that the estimates employed are appropriate and the resulting balances are reasonable; however, due to inherent uncertainties in making estimates, actual results could differ from the original estimates, requiring adjustments to these balances in future periods.