Borrowed Funds - Junior Subordinated Debentures (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2023	Dec. 31, 2022
Debt Instrument
Junior Subordinated Debentures Amount Outstanding (3)	$ 576	$ 575
Capital Securities Amount Outstanding	589
Junior Subordinated Notes, Excluding Adjustments	610
Fair value adjustments, business combination	$ 32
New York Community Capital Trust V (BONUSES Units)
Debt Instrument
Interest Rate of Capital Securities and Debentures	6.00%
Junior Subordinated Debentures Amount Outstanding (3)	$ 147
Capital Securities Amount Outstanding	$ 141
New York Community Capital Trust X
Debt Instrument
Interest Rate of Capital Securities and Debentures	647.00%
Junior Subordinated Debentures Amount Outstanding (3)	$ 124
Capital Securities Amount Outstanding	$ 120
PennFed Capital Trust III
Debt Instrument
Interest Rate of Capital Securities and Debentures	812.00%
Junior Subordinated Debentures Amount Outstanding (3)	$ 31
Capital Securities Amount Outstanding	$ 30
New York Community Capital Trust XI
Debt Instrument
Interest Rate of Capital Securities and Debentures	681.00%
Junior Subordinated Debentures Amount Outstanding (3)	$ 59
Capital Securities Amount Outstanding	$ 58
Flagstar Statutory Trust II
Debt Instrument
Interest Rate of Capital Securities and Debentures	838.00%
Junior Subordinated Debentures Amount Outstanding (3)	$ 26
Capital Securities Amount Outstanding	$ 25
Flagstar Statutory Trust III
Debt Instrument
Interest Rate of Capital Securities and Debentures	808.00%
Junior Subordinated Debentures Amount Outstanding (3)	$ 26
Capital Securities Amount Outstanding	$ 25
Flagstar Statutory Trust IV
Debt Instrument
Interest Rate of Capital Securities and Debentures	798.00%
Junior Subordinated Debentures Amount Outstanding (3)	$ 26
Capital Securities Amount Outstanding	$ 25
Flagstar Statutory Trust V
Debt Instrument
Interest Rate of Capital Securities and Debentures	683.00%
Junior Subordinated Debentures Amount Outstanding (3)	$ 26
Capital Securities Amount Outstanding	$ 25
Flagstar Statutory Trust VI
Debt Instrument
Interest Rate of Capital Securities and Debentures	683.00%
Junior Subordinated Debentures Amount Outstanding (3)	$ 26
Capital Securities Amount Outstanding	$ 25
Flagstar Statutory Trust VII
Debt Instrument
Interest Rate of Capital Securities and Debentures	662.00%
Junior Subordinated Debentures Amount Outstanding (3)	$ 52
Capital Securities Amount Outstanding	$ 50
Flagstar Statutory Trust VIII
Debt Instrument
Interest Rate of Capital Securities and Debentures	633.00%
Junior Subordinated Debentures Amount Outstanding (3)	$ 26
Capital Securities Amount Outstanding	$ 25
Flagstar Statutory Trust IX
Debt Instrument
Interest Rate of Capital Securities and Debentures	632.00%
Junior Subordinated Debentures Amount Outstanding (3)	$ 26
Capital Securities Amount Outstanding	$ 25
Flagstar Statutory Trust X
Debt Instrument
Interest Rate of Capital Securities and Debentures	737.00%
Junior Subordinated Debentures Amount Outstanding (3)	$ 15
Capital Securities Amount Outstanding	$ 15

Junior Subordinated Notes, Excluding Adjustments

No definition available.

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- Definition

This element represents the amount of any measurement period adjustment (as defined) realized during the reporting period to financial liabilities assumed in connection with a business combination for which the initial accounting was incomplete.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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Balance Type:	credit
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- Definition

Value of capital units or capital shares. This element is relevant to issuers of face-amount certificates and registered investment companies.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
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- Definition

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.

+ References

No definition available.

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- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of long-term debt (with maturities initially due after one year or beyond the operating cycle if longer) identified as Junior Subordinated Notes, which have a lower priority than senior instruments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
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