Investment Securities - Summary of Investment Securities (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Debt securities available-for-sale
Amortized Cost	$ 10,535
Equity securities:
Fair Value	14	$ 14
Total Securities
Amortized Cost	11,472	9,958
Gross Unrealized Gain	36	62
Gross Unrealized Loss	959	861
Fair Value	10,549	9,159
Amortized cost of investment securities	3
Interest receivable	$ 41	$ 38
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Other assets	Other assets
Mortgage Backed Securities And Other Securities
Debt securities available-for-sale
Amortized Cost	$ 11,456	$ 9,942
Gross Unrealized Gain	36	62
Gross Unrealized Loss	957	859
Fair Value	10,535	9,145
Mortgage-Related Debt Securities:
Debt securities available-for-sale
Amortized Cost	9,033	7,035
Gross Unrealized Gain	30	56
Gross Unrealized Loss	612	528
Fair Value	8,451	6,563
GSE certificates
Debt securities available-for-sale
Amortized Cost	1,319	1,366
Gross Unrealized Gain	0	1
Gross Unrealized Loss	166	146
Fair Value	1,153	1,221
GSE collateralized mortgage obligations
Debt securities available-for-sale
Amortized Cost	7,551	5,495
Gross Unrealized Gain	24	48
Gross Unrealized Loss	445	381
Fair Value	7,130	5,162
Private label collateralized mortgage obligations
Debt securities available-for-sale
Amortized Cost	163	174
Gross Unrealized Gain	6	7
Gross Unrealized Loss	1	1
Fair Value	168	180
Other Debt Securities:
Debt securities available-for-sale
Amortized Cost	2,423	2,907
Gross Unrealized Gain	6	6
Gross Unrealized Loss	345	331
Fair Value	2,084	2,582
U. S. Treasury obligations
Debt securities available-for-sale
Amortized Cost	0	198
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	0	198
GSE debentures
Debt securities available-for-sale
Amortized Cost	1,652	1,899
Gross Unrealized Gain	0	1
Gross Unrealized Loss	308	291
Fair Value	1,344	1,609
Asset-backed securities
Debt securities available-for-sale
Amortized Cost	271	307
Gross Unrealized Gain	1	0
Gross Unrealized Loss	3	5
Fair Value	269	302
Municipal bonds
Debt securities available-for-sale
Amortized Cost	6	6
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	6	6
Corporate bonds
Debt securities available-for-sale
Amortized Cost	364	365
Gross Unrealized Gain	0	0
Gross Unrealized Loss	23	22
Fair Value	341	343
Foreign notes
Debt securities available-for-sale
Amortized Cost	35	35
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	1
Fair Value	35	34
Capital trust notes
Debt securities available-for-sale
Amortized Cost	95	97
Gross Unrealized Gain	5	5
Gross Unrealized Loss	11	12
Fair Value	89	90
Equity securities:
Equity securities:
Amortized Cost	16	16
Gross Unrealized Loss	2	2
Fair Value	14	14
Mutual funds
Equity securities:
Amortized Cost	16	16
Gross Unrealized Loss	2	2
Fair Value	$ 14	$ 14

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