Basis of Presentation	6 Months Ended
	Jun. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation         The accompanying financial statements of Flagstar Bancorp, Inc. ("Flagstar," or the "Company"), including its wholly owned principal subsidiary, Flagstar Bank, FSB (the "Bank"), have been prepared using GAAP for interim financial statements. Where we say "we," "us," "our," the "Company," "Bancorp" or "Flagstar," we usually mean Flagstar Bancorp, Inc. However, in some cases, a reference to "we," "us," "our," the "Company" or "Flagstar" will include the Bank.        These consolidated financial statements do not include all of the information and footnotes required by GAAP for a full year presentation and certain disclosures have been condensed or omitted in accordance with rules and regulations of the SEC. These interim financial statements are unaudited and include, in our opinion, all adjustments necessary for a fair statement of the results for the periods indicated, which are not necessarily indicative of results which may be expected for the full year. These consolidated financial statements and notes should be read in conjunction with the consolidated financial statements and footnotes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2019, which is available on our website, flagstar.com, and on the SEC website, at sec.gov.