Investment Securities - Summary of Investment Securities (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Debt securities available-for-sale
Amortized Cost	$ 9,145
Fair Value	9,145	$ 9,060
Equity securities:
Fair Value	14	14
Total Securities
Amortized Cost	9,958	9,933
Gross Unrealized Gain	62	14
Gross Unrealized Loss	861	873
Total securities	9,159	9,074
Interest receivable	$ 38	31
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Other assets
Mortgage Backed Securities And Other Securities
Debt securities available-for-sale
Amortized Cost	$ 9,942	9,917
Gross Unrealized Gain	62	14
Gross Unrealized Loss	859	871
Fair Value	9,145	9,060
Mortgage- Related Securities
Debt securities available-for-sale
Amortized Cost	7,035	5,242
Gross Unrealized Gain	56	7
Gross Unrealized Loss	528	460
Fair Value	6,563	4,789
GSE certificates
Debt securities available-for-sale
Amortized Cost	1,366	1,457
Gross Unrealized Gain	1	0
Gross Unrealized Loss	146	160
Fair Value	1,221	1,297
GSE CMOs
Debt securities available-for-sale
Amortized Cost	5,495	3,600
Gross Unrealized Gain	48	1
Gross Unrealized Loss	381	300
Fair Value	5,162	3,301
Private Label CMOs
Debt securities available-for-sale
Amortized Cost	174	185
Gross Unrealized Gain	7	6
Gross Unrealized Loss	1	0
Fair Value	180	191
Debt Securities
Debt securities available-for-sale
Amortized Cost	2,907	4,675
Gross Unrealized Gain	6	7
Gross Unrealized Loss	331	411
Fair Value	2,582	4,271
U. S. Treasury obligations
Debt securities available-for-sale
Amortized Cost	198	1,491
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	4
Fair Value	198	1,487
GSE debentures
Debt securities available-for-sale
Amortized Cost	1,899	1,749
Gross Unrealized Gain	1	0
Gross Unrealized Loss	291	351
Fair Value	1,609	1,398
Asset-backed securities
Debt securities available-for-sale
Amortized Cost	307	375
Gross Unrealized Gain	0	0
Gross Unrealized Loss	5	14
Fair Value	302	361
Municipal bonds
Debt securities available-for-sale
Amortized Cost	6	30
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	6	30
Corporate bonds
Debt securities available-for-sale
Amortized Cost	365	913
Gross Unrealized Gain	0	2
Gross Unrealized Loss	22	30
Fair Value	343	885
Foreign notes
Debt securities available-for-sale
Amortized Cost	35	20
Gross Unrealized Gain	0	0
Gross Unrealized Loss	1	0
Fair Value	34	20
Capital trust notes
Debt securities available-for-sale
Amortized Cost	97	97
Gross Unrealized Gain	5	5
Gross Unrealized Loss	12	12
Fair Value	90	90
Equity Securities
Equity securities:
Amortized Cost	16	16
Gross Unrealized Loss	2
Fair Value	14	14
Total Securities
Gross Unrealized Loss		2
Mutual funds
Equity securities:
Amortized Cost	16	16
Gross Unrealized Loss	2
Fair Value	$ 14	14
Total Securities
Gross Unrealized Loss		$ 2

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