Investment Securities - Maturities of Securities Available for Sale and Held to Maturity (Details) - USD ($) $ in Millions		Dec. 31, 2023	Dec. 31, 2022
Available for sale securities, fair value
Within 1 year		$ 13,243
After 1 year through 5 years		34,782
After 5 years through 10 years		13,806
After 10 years		45,815
Fair Value	[1]	107,646	$ 147,871
Available for sale securities, amortized cost
Within 1 year		13,427
After 1 year through 5 years		36,943
After 5 years through 10 years		15,345
After 10 years		50,640
Amortized Cost		$ 116,355
Weighted-average yield
Within 1 year		1.82%
After 1 year through 5 years		1.84%
After 1 year through 5 years		1.87%
After 10 years		2.62%
Total		2.18%
Held to maturity securities, fair value
Within 1 year		$ 1,217
After 1 year through 5 years		7,765
After 5 years through 10 years		37,584
After 10 years		100,525
Fair Value		147,091	158,936
Held to maturity securities, amortized cost
Within 1 year		1,248
After 1 year through 5 years		8,198
After 5 years through 10 years		40,139
After 10 years		109,867
Amortized Cost		$ 159,452
Weighted-average yield
Within 1 year		2.61%
After 1 year through 5 years		1.98%
After 5 years through 10 years		1.76%
After 10 years		1.73%
Total		1.75%
Portfolio layer method fair value hedge basis adjustments, excluded from amortized cost of available for sale securities		$ 19
U.S. agency mortgage-backed securities
Available for sale securities, fair value
Within 1 year		798
After 1 year through 5 years		11,126
After 5 years through 10 years		10,650
After 10 years		40,221
Fair Value		62,795	77,688
Held to maturity securities, fair value
Within 1 year		1,217
After 1 year through 5 years		7,765
After 5 years through 10 years		37,584
After 10 years		100,525
Fair Value		147,091	158,936
U.S. Treasury securities
Available for sale securities, fair value
Within 1 year		9,142
After 1 year through 5 years		12,329
After 5 years through 10 years		0
After 10 years		0
Fair Value		21,471	40,002
Corporate debt securities
Available for sale securities, fair value
Within 1 year		2,708
After 1 year through 5 years		8,306
After 5 years through 10 years		1,470
After 10 years		0
Fair Value		12,484	12,555
Asset-backed securities
Available for sale securities, fair value
Within 1 year		0
After 1 year through 5 years		2,443
After 5 years through 10 years		1,290
After 10 years		5,354
Fair Value		9,087	13,023
Foreign government agency securities
Available for sale securities, fair value
Within 1 year		495
After 1 year through 5 years		507
After 5 years through 10 years		0
After 10 years		0
Fair Value		1,002	969
U.S. state and municipal securities
Available for sale securities, fair value
Within 1 year		0
After 1 year through 5 years		71
After 5 years through 10 years		396
After 10 years		112
Fair Value		579	638
Non-agency commercial mortgage-backed securities
Available for sale securities, fair value
Within 1 year		0
After 1 year through 5 years		0
After 5 years through 10 years		0
After 10 years		109
Fair Value		109	450
Certificates of deposit
Available for sale securities, fair value
Within 1 year		100
After 1 year through 5 years		0
After 5 years through 10 years		0
After 10 years		0
Fair Value		100	2,231
Other
Available for sale securities, fair value
Within 1 year		0
After 1 year through 5 years		0
After 5 years through 10 years		0
After 10 years		19
Fair Value		$ 19	$ 315

[1] Certain prior year amounts have been reclassified to conform to the current year presentation. See Note 1 for additional information.