Investment Securities - AFS Securities in an Unrealized Loss Position (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
AFS securities
AFS: Fair value, less than 12 months	$ 22,717	$ 19,172
AFS: Fair value, 12 months or longer	49,653	57,983
AFS: Fair value, total	72,370	77,155
AFS: Gross unrealized losses, less than 12 months	42	69
AFS: Gross unrealized losses, 12 months or longer	2,942	4,041
AFS: Gross unrealized losses, total	2,984	4,110
U.S. Treasury securities
AFS securities
AFS: Fair value, less than 12 months	21,410	14,295
AFS: Fair value, 12 months or longer	23,865	33,458
AFS: Fair value, total	45,275	47,753
AFS: Gross unrealized losses, less than 12 months	30	22
AFS: Gross unrealized losses, 12 months or longer	470	1,081
AFS: Gross unrealized losses, total	500	1,103
U.S. agency securities
AFS securities
AFS: Fair value, less than 12 months	638	4,297
AFS: Fair value, 12 months or longer	20,163	18,459
AFS: Fair value, total	20,801	22,756
AFS: Gross unrealized losses, less than 12 months	1	43
AFS: Gross unrealized losses, 12 months or longer	2,097	2,485
AFS: Gross unrealized losses, total	2,098	2,528
Agency CMBS
AFS securities
AFS: Fair value, less than 12 months	25	0
AFS: Fair value, 12 months or longer	5,105	5,415
AFS: Fair value, total	5,130	5,415
AFS: Gross unrealized losses, less than 12 months	0	0
AFS: Gross unrealized losses, 12 months or longer	365	456
AFS: Gross unrealized losses, total	365	456
State and municipal securities
AFS securities
AFS: Fair value, less than 12 months	620	524
AFS: Fair value, 12 months or longer	36	35
AFS: Fair value, total	656	559
AFS: Gross unrealized losses, less than 12 months	11	3
AFS: Gross unrealized losses, 12 months or longer	2	2
AFS: Gross unrealized losses, total	13	5
FFELP student loan ABS:
AFS securities
AFS: Fair value, less than 12 months	24	56
AFS: Fair value, 12 months or longer	484	616
AFS: Fair value, total	508	672
AFS: Gross unrealized losses, less than 12 months	0	1
AFS: Gross unrealized losses, 12 months or longer	8	17
AFS: Gross unrealized losses, total	$ 8	$ 18

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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