Borrowed Funds - Contractual Terms of Junior Subordinated Debentures Outstanding (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021
Subordinated Borrowing [Line Items]
Junior Subordinated Debentures Amount Outstanding		$ 575	$ 361
Junior Subordinated Debentures Amount Outstanding		608	$ 361
Capital Securities Amount Outstanding		$ 588
New York Community Capital Trust V (BONUSES Units)
Subordinated Borrowing [Line Items]
Interest Rate of Capital Securities and Debentures	[1]	6.00%
Junior Subordinated Debentures Amount Outstanding	[1]	$ 147
Capital Securities Amount Outstanding	[1]	$ 141
Date of Original Issue	[1]	Nov. 04, 2002
Stated Maturity	[1]	Nov. 01, 2051
New York Community Capital Trust X
Subordinated Borrowing [Line Items]
Interest Rate of Capital Securities and Debentures	[2]	6.37%
Junior Subordinated Debentures Amount Outstanding	[2]	$ 124
Capital Securities Amount Outstanding	[2]	$ 120
Date of Original Issue	[2]	Dec. 14, 2006
Stated Maturity	[2]	Dec. 15, 2036
PennFed Capital Trust III
Subordinated Borrowing [Line Items]
Interest Rate of Capital Securities and Debentures	[2]	8.02%
Junior Subordinated Debentures Amount Outstanding	[2]	$ 31
Capital Securities Amount Outstanding	[2]	$ 30
Date of Original Issue	[2]	Jun. 02, 2003
Stated Maturity	[2]	Jun. 15, 2033
New York Community Capital Trust XI
Subordinated Borrowing [Line Items]
Interest Rate of Capital Securities and Debentures	[2]	6.38%
Junior Subordinated Debentures Amount Outstanding	[2]	$ 59
Capital Securities Amount Outstanding	[2]	$ 58
Date of Original Issue	[2]	Apr. 16, 2007
Stated Maturity	[2]	Jun. 30, 2037
Flagstar Statutory Trust II
Subordinated Borrowing [Line Items]
Interest Rate of Capital Securities and Debentures	[2]	7.97%
Junior Subordinated Debentures Amount Outstanding	[2]	$ 26
Capital Securities Amount Outstanding	[2]	$ 25
Date of Original Issue	[2]	Dec. 26, 2002
Stated Maturity	[2]	Dec. 26, 2032
Flagstar Statutory Trust III
Subordinated Borrowing [Line Items]
Interest Rate of Capital Securities and Debentures	[2]	7.33%
Junior Subordinated Debentures Amount Outstanding	[2]	$ 26
Capital Securities Amount Outstanding	[2]	$ 25
Date of Original Issue	[2]	Feb. 19, 2003
Stated Maturity	[2]	Apr. 07, 2033
Flagstar Statutory Trust IV
Subordinated Borrowing [Line Items]
Interest Rate of Capital Securities and Debentures	[2]	7.98%
Junior Subordinated Debentures Amount Outstanding	[2]	$ 26
Capital Securities Amount Outstanding	[2]	$ 25
Date of Original Issue	[2]	Mar. 19, 2003
Stated Maturity	[2]	Mar. 19, 2033
Flagstar Statutory Trust V
Subordinated Borrowing [Line Items]
Interest Rate of Capital Securities and Debentures	[2]	6.08%
Junior Subordinated Debentures Amount Outstanding	[2]	$ 26
Capital Securities Amount Outstanding	[2]	$ 25
Date of Original Issue	[2]	Dec. 29, 2004
Stated Maturity	[2]	Jan. 07, 2035
Flagstar Statutory Trust VI
Subordinated Borrowing [Line Items]
Interest Rate of Capital Securities and Debentures	[2]	6.08%
Junior Subordinated Debentures Amount Outstanding	[2]	$ 26
Capital Securities Amount Outstanding	[2]	$ 25
Date of Original Issue	[2]	Mar. 30, 2005
Stated Maturity	[2]	Apr. 07, 2035
Flagstar Statutory Trust VII
Subordinated Borrowing [Line Items]
Interest Rate of Capital Securities and Debentures	[2]	6.52%
Junior Subordinated Debentures Amount Outstanding	[2]	$ 51
Capital Securities Amount Outstanding	[2]	$ 50
Date of Original Issue	[2]	Mar. 29, 2005
Stated Maturity	[2]	Jun. 15, 2035
Flagstar Statutory Trust VIII
Subordinated Borrowing [Line Items]
Interest Rate of Capital Securities and Debentures	[2]	5.58%
Junior Subordinated Debentures Amount Outstanding	[2]	$ 25
Capital Securities Amount Outstanding	[2]	$ 24
Date of Original Issue	[2]	Sep. 22, 2005
Stated Maturity	[2]	Oct. 07, 2035
Flagstar Statutory Trust IX
Subordinated Borrowing [Line Items]
Interest Rate of Capital Securities and Debentures	[2]	6.22%
Junior Subordinated Debentures Amount Outstanding	[2]	$ 25
Capital Securities Amount Outstanding	[2]	$ 24
Date of Original Issue	[2]	Jun. 28, 2007
Stated Maturity	[2]	Sep. 15, 2037
Flagstar Statutory Trust X
Subordinated Borrowing [Line Items]
Interest Rate of Capital Securities and Debentures	[2]	7.27%
Junior Subordinated Debentures Amount Outstanding	[2]	$ 16
Capital Securities Amount Outstanding	[2]	$ 16
Date of Original Issue	[2]	Aug. 31, 2007
Stated Maturity	[2]	Sep. 15, 2037

[1] Callable subject to certain conditions as described in the prospectus filed with the SEC on November 4, 2002.

[2] Callable at any time.