Investment Securities - Investment Securities in an Unrealized Loss Position (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
AFS securities
AFS: Fair value, less than 12 months	$ 69,078	$ 46,955
AFS: Fair value, 12 months or longer	12,879	1,775
AFS: Fair value, total	81,957	48,730
AFS: Gross unrealized losses, less than 12 months	4,069	607
AFS: Gross unrealized losses, 12 months or longer	1,883	32
AFS: Gross unrealized losses, total	5,952	639
U.S. Treasury securities
AFS securities
AFS: Fair value, less than 12 months	46,061	31,459
AFS: Fair value, 12 months or longer	6,673	0
AFS: Fair value, total	52,734	31,459
AFS: Gross unrealized losses, less than 12 months	1,923	296
AFS: Gross unrealized losses, 12 months or longer	581	0
AFS: Gross unrealized losses, total	2,504	296
U.S. agency securities
AFS securities
AFS: Fair value, less than 12 months	15,301	12,283
AFS: Fair value, 12 months or longer	5,708	1,167
AFS: Fair value, total	21,009	13,450
AFS: Gross unrealized losses, less than 12 months	1,602	219
AFS: Gross unrealized losses, 12 months or longer	1,277	22
AFS: Gross unrealized losses, total	2,879	241
Agency CMBS
AFS securities
AFS: Fair value, less than 12 months	5,373	2,872
AFS: Fair value, 12 months or longer	104	10
AFS: Fair value, total	5,477	2,882
AFS: Gross unrealized losses, less than 12 months	437	89
AFS: Gross unrealized losses, 12 months or longer	12	0
AFS: Gross unrealized losses, total	449	89
State and municipal securities
AFS securities
AFS: Fair value, less than 12 months	1,536	21
AFS: Fair value, 12 months or longer	46	7
AFS: Fair value, total	1,582	28
AFS: Gross unrealized losses, less than 12 months	88	2
AFS: Gross unrealized losses, 12 months or longer	2	0
AFS: Gross unrealized losses, total	90	2
FFELP student loan ABS:
AFS securities
AFS: Fair value, less than 12 months	807	320
AFS: Fair value, 12 months or longer	348	591
AFS: Fair value, total	1,155	911
AFS: Gross unrealized losses, less than 12 months	19	1
AFS: Gross unrealized losses, 12 months or longer	11	10
AFS: Gross unrealized losses, total	$ 30	$ 11

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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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Amount of accumulated unrealized loss on 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 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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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 less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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