Business Combination - Summary of Fair Value of Assets Acquired and Liabilities and Equity Assumed (Details) - Flagstar $ in Millions	Dec. 01, 2022 USD ($)
Business Acquisition [Line Items]
Purchase price consideration	$ 2,010
Fair value of assets acquired:
Cash & cash equivalents	331
Securities	2,695
Loans held for sale	1,257
Loans held for investment	18,008
CDI and other intangible assets	292
Mortgage servicing rights	1,012
Other assets	2,158
Total assets acquired	25,753
Fair value of liabilities assumed:
Deposits	15,995
Borrowings	6,700
Other liabilities	889
Total liabilities assumed	23,584
Fair value of net identifiable assets	2,169
Bargain purchase gain	159
One-to-Four Family First Mortgage
Fair value of assets acquired:
Loans held for investment	5,438
Commercial Real Estate
Fair value of assets acquired:
Loans held for investment	3,891
Commercial and Industrial
Fair value of assets acquired:
Loans held for investment	6,523
Consumer and Other
Fair value of assets acquired:
Loans held for investment	$ 2,156

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Business combination recognized identifiable assets acquired and liabilities assumed core deposit and other intangible assets.

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Business combination recognized identifiable assets acquired and liabilities assumed deposits.

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Business combination recognized identifiable assets acquired and liabilities assumed loans held for investment.

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Business combination recognized identifiable assets acquired and liabilities assumed loans held for sale.

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Business combination recognized identifiable assets acquired and liabilities assumed mortgage servicing rights.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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Amount of assets acquired at the acquisition date.

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Amount of currency on hand as well as demand deposits with banks or financial institutions, acquired at the acquisition date. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount of investments in debt and equity securities, including, but not limited to, held-to-maturity, trading and available-for-sale expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer, acquired at the acquisition date.

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Amount of other assets expected to be realized or consumed before one year or the normal operating cycle, if longer, acquired at the acquisition date.

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Amount of long-term debt due within one year or within the normal operating cycle, if longer, assumed at the acquisition date.

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Amount of other liabilities due within one year or within the normal operating cycle, if longer, assumed at the acquisition date.

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Amount of liabilities assumed at the acquisition date.

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Amount recognized as of the acquisition date for the identifiable assets acquired in excess of (less than) the aggregate liabilities assumed.

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